Kim, H.; Yoo, H.J., and Lee, J.L., 2021. Nonlinear Kernel Convolutional Neural Network to find median sand particle size. In: Lee, J.L.; Suh, K.-S.; Lee, B.; Shin, S., and Lee, J. (eds.), Crisis and Integrated Management for Coastal and Marine Safety. Journal of Coastal Research, Special Issue No. 114, pp. 1-5. Coconut Creek (Florida), ISSN 0749-0208.

Convolutional Neural Network (CNN) has successfully been used in various areas. We focus on predicting various sand particle sizes by applying convolutional neural network with a nonlinear kernel. The nonlinear kernel involves a bias and negative square of subtraction between input image pixel numbers and the kernel coefficients and summation. The convolution layer conform new feature map in Convolutional Neural Network. While using batch gradient descent method to train relevant coefficients and biases, the gradient of the square of subtraction term appears in the whole gradient over each kernel coefficient. The network was examined on regular-sized sands, i.e. 2000, 1000, 500, 250, 125 and 63 micrometer. The network was trained by using various images for each size. It was validated against new images and the absolute error was less than 30 micrometer, respectively, which is satisfactory. The network was applied by using 3 images of sands with size distribution. The results show good validation and satisfactory predictions. In the course of study, several numbers of kernels, kernel sizes, pooling sizes were tried and the optimum architecture for this work was chosen. It is expected that the present network will reduce time and effort in obtaining median sand size in many field projects. The size distribution of sand particles could also be obtained with the present network in the near future.

Yoo, H.J.; Kim, H.; Lee, J.L., and Park, J.Y., 2021. Asymmetry between accretional advance and erosional retreat of shoreline position in on-offshore direction. In: Lee, J.L.; Suh, K.-S.; Lee, B.; Shin, S., and Lee, J. (eds.), Crisis and Integrated Management for Coastal and Marine Safety. Journal of Coastal Research, Special Issue No. 114, pp. 6–10. Coconut Creek (Florida), ISSN 0749-0208.

Episodic shoreline retreat often slowed recovery in low frequency periods (weeks or months). The asymmetry between wave energy rise and collapse is closely related to the asymmetry of shoreline advancement and retreat, but the latter is more pronounced due to the different profile adjustment processes. Long-term wave time series data and shoreline time series data were analyzed at Won-pyeong beach located on the east coast of Korea. When waves such as storms come into the beach, the shoreline quickly retreated, and in relatively quiet times, the beach slowly recovered to it's original position. Also, the asymmetry of the shoreline position with respect to time is stronger than that of the wave height. A methodology is proposed here, and the envelope rope curve can be used to predict profile and average shoreline changes in the reference section for erosion steps such as storms.The proposed equation was in good agreement for shoreline asymmetry position, and is satisfactory. Empirical formular are slightly different in the relatively calm period, this is an artificial change formed by external pressure conditions such as artificial nourishment. Several variables were used as correction factors. It`s important for future research to propose standardized correction factors and ranges by applying them at various sites.

Lee, D.S.; Cho, W.C., and Lee, K.J., 2021. Experimental study on estimation of water level rise behind a low-crested structure using water level-discharge relationship. In: Lee, J.L.; Suh, K.-S.; Lee, B.; Shin, S., and Lee, J. (eds.), Crisis and Integrated Management for Coastal and Marine Safety. Journal of Coastal Research, Special Issue No. 114, pp. 11–15. Coconut Creek (Florida), ISSN 0749-0208.

Low-crested structures (LCSs) that are installed to reduce the incoming wave height, such as detached and submerged breakwater structures, allow more overflow than do general breakwater structures and increase the water level behind the structure. In the LCS design stage, because the increased water level distorts the results of laboratory experiments, the effect of the rise in the water level must be determined. In this study, an experiment was conducted to determine the water level-discharge relationship and analyze the characteristics of the water level rise behind permeable and impermeable LCSs with various wave conditions. It is found that the slopes of the water level-discharge relationship with the same significant wave period are approximately identical for the permeable and impermeable LCSs. In addition, the slopes of the water level-discharge relationship for different significant wave heights are linear for the permeable LCSs but not for the impermeable LCSs. These results can be useful for selecting a suitable planar configuration for LCSs in field site applications.

Lee, H., 2021. Propagation of solitary wave around conical island in level-set finite element framework. In: Lee, J.L.; Suh, K.-S.; Lee, B.; Shin, S., and Lee, J. (eds.), Crisis and Integrated Management for Coastal and Marine Safety. Journal of Coastal Research, Special Issue No. 114, pp. 16–20. Coconut Creek (Florida), ISSN 0749-0208.

Though the solitary wave is a single wave, it consists of a complex spectrum of frequencies, which enables in-depth analysis and reliable generation both in the laboratory and in the numerical model. For these reasons, solitary waves are known to be a good candidate for the description of waves including tsunamis since they effectively model the important effects of the long wave on the coasts very well. In addition, it is supposed to propagate over constant depth without appreciable changes, allowing for consistent referencing of its offshore or incident wave height. In this study, the level-set scheme, which is combined with the incompressible Navier-Stokes solver based on the fractional step algorithm in the framework of the finite element method, was applied to the modeling of wave propagation and runup on a circular conical island. Unstructured hexahedral meshes were generated for this purpose and MPI (Message Passing Interface) based parallel algorithms were developed to accelerate the computation. The physical behavior of waves are discussed in detail and the numerical results (e.g., runup heights) are compared with the experimental data. The good agreements were observed.

Lee, G.S.; Lee, U.J., and Cho, H.Y., 2021. The probability density estimation of wave direction data in Korea. In: Lee, J.L.; Suh, K.-S.; Lee, B.; Shin, S., and Lee, J. (eds.), Crisis and Integrated Management for Coastal and Marine Safety. Journal of Coastal Research, Special Issue No. 114, pp. 21–25. Coconut Creek (Florida), ISSN 0749-0208.

Although wave direction is important information along with wave height and period, distribution estimation studies have been limited to traditional schematic analysis, including rose diagrams. In addition, studies on the estimation of the distribution function of wave direction are relatively insufficient compared to wave height and period distribution. In this study, estimations of basic statistical information and the distribution function were performed using hourly wave direction data at 16 points in the last 4 years (2016-2019) measured by the KMA (Korea Meteorological Administration) buoy. The von Mises Mixture (VMM) distribution function was used to estimate the directional data distribution, and the optimal parameters for each order were estimated using the EM algorithm. The optimal order was selected based on Bayesian Information Criterion (BIC), and generally, 4-5 VMM distribution functions were identified as the optimal distribution functions (70%). The optimal VMM distribution function was compared with the histogram and the non-parametric method for Kernel Density estimation. In addition, quantitative analysis was performed on the temporal change pattern of the mean and standard deviation of the direction data corresponding to a representative statistical measure. As a result of the analysis, it was found that a multimodal distribution was appropriate for estimating wave direction according to the overall stations and times. Therefore, one representative wave direction and standard deviation information was found to be insufficient for estimating the distribution type, and the parameters (weighting coefficient, mean, and variance) of the VMM model were found to be more effective for estimating the distribution type. The results of this study can be used in various fields of coastal engineering that require the input of wave information (coastal transport and predominance of design waves).

Lee, B.W.; Won, D.; Kim, D.H., and Park, W.-S., 2021. Model tests for evaluating the bearing pressure of harbor structures using open cell caisson method. In: Lee, J.L.; Suh, K.-S.; Lee, B.; Shin, S., and Lee, J. (eds.), Crisis and Integrated Management for Coastal and Marine Safety. Journal of Coastal Research, Special Issue No. 114, pp. 26–30. Coconut Creek (Florida), ISSN 0749-0208.

This study is related to the ground bearing pressure of a caisson-type harbor structure. In particular, it was examined the ground bearing pressure of the harbor structure to which the open cell caisson method was developed to increase stability by interlocking caissons. An experimental study was conducted to confirm the performance for the ground bearing pressure with a construction method that significantly improved the sliding stability of the structure by filling crushed stones between two adjacent open cells. A small scale caisson model and four load cells were used to evaluate the change of the ground bearing pressure due to the action of a horizontal load. The validity of experiment results was confirmed through comparison with numerical results using ABAQUS. As a result of the experiment, it was confirmed that the open cell caisson method showed superior characteristics for the ground bearing pressure compared to the conventional caisson method. As the degree of compaction of crushed stones increased, the ground bearing pressure was further reduced, and an increase in the coefficient of friction on the side wall had a great influence on a decrease. The end bearing pressure was reduced by 46% even in the condition that crushed stones were not compacted and the side wall was not uneven (frictional coefficient 0.47), and in the condition with unevenness (frictional coefficient 0.787), it decreased by 70%. When the condition for compacting fully crushed stones was added, the result was reduced up to 77%.

Yoon, Y.-K.; Lee, S.-W., and Yoon, J.-J., 2021. Assessment of the degree of contamination in marine sediments at Cheonsu Bay, west coast of Korea. In: Lee, J.L.; Suh, K.-S.; Lee, B.; Shin, S., and Lee, J. (eds.), Crisis and Integrated Management for Coastal and Marine Safety. Journal of Coastal Research, Special Issue No. 114, pp. 31–35. Coconut Creek (Florida), ISSN 0749-0208.

In this study, 32 bottom sediments (30 sites on the surface and 2 sites in the core) were sampled to determine thedegree of marine sediment contamination in Cheonsu Bay. Cleanup indexes of eutrophication (CIET) and harmful chemicals (CHIC) were calculated to determine whether remediation of contaminated sediment was necessary. Generally, an area with CIET ≥ 6 or CHIC ≥ 2 requires cleanup. In the case of Cheonsu Bay, its CEIT value was six or higher at six sites located in the northern area of Cheonsu Bay. The analysis revealed that there was a significant level of organic matter pollution in this region. However, its CHIC was lower than 2 at all sites, indicating that the level of contamination caused by heavy metal pollutants was not high. Core samples were collected up to a depth of 60 cm from the surface at two sites in which CIET was assessed to be greater than 6. Analysis of the core samples indicated that organic matter contamination was present up to a depth of 20–30 cm from the surface. It was inferred that the polluted matter originated from Bunam Lake and Ganwol Lake, which are located to the north of Cheonsu Bay and have highly polluted water and bottom sediments. The results of this study prove that organic matter contamination because of these freshwater lakes has a continuous effect on the sediments in the inner Cheonsu Bay region. To mitigate the degree of contamination in the Cheonsu Bay area, fundamental countermeasures should focus on the source of terrestrial pollutants.

Lee, J.-H.; Woo, H.J.; Jung, H.-S.; Park, H.N.; Jeong, E.-Y., and Jeong, J.B., 2021. Characteristics of the wind distribution using automatic weather system observation data over the Doyo-deung barrier islands off the coast of the Nakdong River estuary, Busan, South Korea. In: Lee, J.L.; Suh, K.-S.; Lee, B.; Shin, S., and Lee, J. (eds.), Crisis and Integrated Management for Coastal and Marine Safety. Journal of Coastal Research, Special Issue No. 114, pp. 36–40. Coconut Creek (Florida), ISSN 0749-0208.

This study was conducted to the Nakdong marine environmental information system (N-MEIS) using automatic weather station (AWS) observation data to elucidate the characteristics of the wind distribution, focusing on and land and sea breezes, over the Doyo-deung barrier islands in the brackish water zone off the coast of the Nakdong River Estuary, Busan, South Korea. From May 2015 to the present, the N-MEIS was run in real-time using 4th Generation (4G) long term evolution (LTE) communication, with a coverage rate of approximately 98% from AWS, along with periodic marine observations recorded one to four times per year. From April 2016 to August 2020, the average monthly wind speed over the Doyo-deung barrier islands was 3.82 m/s (range, 2.10–5.10 m/s) and the maximum wind speed, recorded in February 2019, was 46.80 m/s. These values are generally influenced by low-pressure cyclones or gusty winds. However, the maximum monthly mean velocity may be influenced by typhoons occurring in early autumn, from August to September. Based on the percentage of each wind direction, the prevailing winds are from the N, NNE, SSW, and NNW. The distribution of wind directions in summer was similar to that in spring, while that in autumn tended to be similar to that in winter. However, considering only wind speeds of 5.00 m/s or more, which can cause the movement of sand particles, N, SSW, and NNW winds are overwhelmingly dominant, at 38.7%. Research into the dynamic wind distribution is essential to effectively managing erosion and sedimentation around barrier islands, beach pollution from floating materials transported overland, coastal sand dune activity, changes in migratory bird habitats, and impacts on ecosystem health. The evolution and development of the N-MEIS will facilitate this process. Future studies should integrate real-time data with periodic marine observations and predictions and environmental sensitivity index maps.

Jeong, J.B.; Woo, H.J.; Jung, H.-S.; Park, H.N.; Kim, T.-J, and Lee, J.-H., 2021. Monsoon-influenced deposition systems in a rhodolith beach on Udo Island, Korea. In: Lee, J.L.; Suh, K.-S.; Lee, B.; Shin, S., and Lee, J. (eds.), Crisis and Integrated Management for Coastal and Marine Safety. Journal of Coastal Research, Special Issue No. 114, pp. 41–45. Coconut Creek (Florida), ISSN 0749-0208.

A beach on Udo Island, off the coast of Jeju Island, Korea was formed by long-term deposition of rhodoliths, which comprise more than 99% of all deposits on the beach. This phenomenon is very rare on the global scale. This rhodolith beach in 2004 was designated a natural monument to preserve its geoheritage. However, to date, no geological studies have been conducted to examine its sedimentary mechanisms and properties. Recent tourist developments and climate change have raised the possibility of erosion on the rhodolith beach. The objective of the present study was to examine the evolution and sedimentation characteristics of this beach through analysis of grain size and aerial photographs, and seasonal beach surveys. Geomorphologically, the beach is divided into reef areas to the north, with high altitudes and rocks mainly distributed along the coastline, and sandy beach to the south, which is strongly affected by waves and tidal currents. Particle sizes decrease toward the upper part of the beach, with gravel-sized sediments in the south and sand-sized sediments in the north. The mean grain size of deposited sediments increases from spring to autumn. In spring, the beach experiences greater erosion in the north and deposition in the south, whereas in summer, the opposite trends are seen. The sediment deposition volume is largest in autumn. There is also annual variation, where the beach was dominated by erosion in three recent years due to a decrease in sediment volume toward the south. The beach increased in volume from 1985 to 2003, and decreased thereafter. Due to the influence of the East Asian Monsoon, the beach experiences typhoons in summer and north-northwesterly waves and tidal currents in autumn and winter. However, erosion occurs in in the south due to a lack of berm for rhodoliths deposition.

Oh, S.-H. and Park, W.S., 2021. Experimental comparison of hydrodynamic characteristics of submerged floating tunnel with different cross-sectional shape. In: Lee, J.L.; Suh, K.-S.; Lee, B.; Shin, S., and Lee, J. (eds.), Crisis and Integrated Management for Coastal and Marine Safety. Journal of Coastal Research, Special Issue No. 114, pp. 46–50. Coconut Creek (Florida), ISSN 0749-0208.

This study conducted physical experiments to investigate hydrodynamic characteristics of the submerged floating tunnel (SFT) under wave loading, when the cross-sectional shape of the SFT was either oval or rectangular. By analyzing the experimental data, the performance of the two SFT models were compared with that of the conventional SFT of circular cross-section, which already reported by a previous study (Oh et al., 2013). The experimental results showed that the tensile forces on the tethering lines and the associated wave pressures on the SFT body apparently vary according to the change of the cross-sectional shape of the SFT. In general, the rectangular cross-section was less effective because the tensile forces on the tethering lines and the pressures on the SFT body were greater than those of the oval cross-section.

Ko, D.-H.; Lee, U.-J.; Cho, H., and Lee, B.W., 2021. Estimation of relations between representative wave heights using measured wave data for the west sea of Korea. In: Lee, J.L.; Suh, K.-S.; Lee, B.; Shin, S., and Lee, J. (eds.), Crisis and Integrated Management for Coastal and Marine Safety. Journal of Coastal Research, Special Issue No. 114, pp. 51–55. Coconut Creek (Florida), ISSN 0749-0208.

The Rayleigh distribution was first defined as the distribution of individual wave heights for irregular waves. The relationships between representative wave heights have since been determined by manipulating the probability density function of the Rayleigh distribution. However, since the Rayleigh distribution is based on the linear wave theory assumption for narrow-band spectra, it is necessary to examine its applicability to shallow water. Thus, in this study, individual wave heights were calculated using water surface elevation data (2013.08.01 - 31) obtained from the HeMOSU-1 offshore measurement tower. The zero-up crossing method was used to define individual waves, and representative wave heights of highest, significant, highest one-tenth, mean, and root mean square waves were calculated using individual waves for 20 minutes. The Kolmogorov-Smirnov (K-S) test was used to determine the goodness of fit of the Rayleigh distribution for individual wave heights. Relationships between representative wave heights were also estimated and compared to the theoretical relationships. Approximately 91% of the total data did not follow the Rayleigh distribution. Meanwhile, the estimated coefficients of relationships (y = α × x) were compared to theoretical coefficients. The estimates obtained are greater than the theoretical estimates derived from the Rayleigh distribution with an error range of 1.68% to 13.25%.

Park, M.; Kim, H.S.; Choi, S., and Ryu, Y.-U., 2021. PIV and BIV measurements of roller in hydraulic jumps. In: Lee, J.L.; Suh, K.-S.; Lee, B.; Shin, S., and Lee, J. (eds.), Crisis and Integrated Management for Coastal and Marine Safety. Journal of Coastal Research, Special Issue No. 114, pp. 56–60. Coconut Creek (Florida), ISSN 0749-0208.

This study performed an experimental investigation on roller in hydraulic jump. Based on the similarity between tidal bore and hydraulic jump, the turbulence flow and free surface fluctuation of the hydraulic jump roller were analyzed with adjustment of downstream water level. To obtain instantaneous flow field including bubbly flow, PIV and BIV technique with shadowgraphy was applied. The result found that the streamwise turbulent flow was dominated at the lower part of roller while the vertical turbulence increased near the water surface of roller in hydraulic jump. The water level showed a large fluctuation as a hydraulic jump occurred. These challenges identified the detailed view of velocity and free surface of roller region can be provided using image analysis.

Lee, U.-J.; Lee, G.-S.; Ko, D.-H., and Cho, H.-Y., 2021. Optimal smoothing of the wave spectrum using HeMOSU-1 data. In: Lee, J.L.; Suh, K.-S.; Lee, B.; Shin, S., and Lee, J. (eds.), Crisis and Integrated Management for Coastal and Marine Safety. Journal of Coastal Research, Special Issue No. 114, pp. 61–65. Coconut Creek (Florida), ISSN 0749-0208.

An optimal model based on water surface elevation can be regarded as an optimal smoothing model, which estimates the optimal range of smoothing and can be considered a corresponding model. The optimal model is a process that classifies observation data either into a structure that can be statistically analyzed or into signal and noise components that can be given meaning, and the signal component becomes the optimal estimation model. In general, wave spectrum analysis is performed through water surface elevation data. In this study, the error generated during the process of smoothing the estimated spectrum is minimized by using a statistical estimation method that tracks the optimal bandwidth. For optimal smoothing, spectral data estimated through WaveGuide, a wave observation HeMOSU-1 device installed in Wido-Anmado, Southwest Korea were used. To optimize the estimated spectrum, the optimal bandwidth was estimated through the ‘locpoly’ function in the ‘KernSmooth’ package included in the R data analysis program, and the optimal smoothing with other functions was compared and analyzed. As a result of the analysis, the optimal bandwidth of the southwestern sea area, which was the analysis point, was estimated to be 0.021 ± 10%, and it was confirmed that the optimal bandwidth had a negative correlation with the wave height.

Gu, B.-H.; Woo, S.-B., and Kim, S., 2021. Optimization of influencing factors in tidal current data assimilation modeling in macro tidal estuary, Gyeonggi Bay, South Korea. In: Lee, J.L.; Suh, K.-S.; Lee, B.; Shin, S., and Lee, J. (eds.), Crisis and Integrated Management for Coastal and Marine Safety. Journal of Coastal Research, Special Issue No. 114, pp. 66–70. Coconut Creek (Florida), ISSN 0749-0208.

The study investigates the effect of the model prediction accuracy improvement using data assimilation technique in macro-tidal estuary, such as the Gyeonggi Bay (GGB), South Korea. The observation data used in this study is a tidal current measurement from Acoustic Doppler Current Profiler (ADCP) mooring device. GGB is located at the middle west coast of South Korea, and it is semi-closed estuary that has a tidal range over 6.8 m. To take the irregularity of coastline into account, this study utilized the Finite Volume Coastal Ocean Model (FVCOM), which has the flexible advantage of grid resolution by using unstructured triangular grid system. When applying data assimilation into the coastal model, various parameters, such as scaling factors and correlation lengths are needed to be adjusted to find out the best performance. Total 25 cases used in Taylor diagram showed that different influencing factors are required to be optimized at each observation location. It means that parameters in data assimilation depend on the physical dynamic system via complicated geometry. The optimized parameters not only increase by the tidal range but also it is offset by the effect of river discharge. The horizontal influence range of data assimilation with all observed locations becomes even less than the result applying only one location. It is estimated that the phenomena occurred due to strong tidal currents and interference between the range of influence. The sensitivity of data assimilation parameters in tidally dominated coastal area indicates that a systematic way of choosing the most optimized site-specific parameters are required in macro tidal area.

Park, Y.H. and Youn, D., 2021. Characteristics of storm surge based on the forward speed of the storm. In: Lee, J.L.; Suh, K.-S.; Lee, B.; Shin, S., and Lee, J. (eds.), Crisis and Integrated Management for Coastal and Marine Safety. Journal of Coastal Research, Special Issue No. 114, pp. 71–75. Coconut Creek (Florida), ISSN 0749-0208.

Storm surge is determined by the attributes of the storm and several other factors. The forward speed of a storm is known to increase the wave height, but its effect on storm surges has not yet been studied in detail. This study focused on the forward speed of storms approaching the Korean Peninsula, which has been getting slower due to climate change. The forward speed continued to change along the track of the storm until extinction. Despite the difficulties caused by the changes in the moving direction and forward speed of storms, this study investigates the effects of their forward speed on the storm surge using the ADCIRC numerical model. Variations in storm surge due to the forward speed of real and virtual storms were studied by simplifying the other factors. Many test simulations were conducted under various conditions, such as steady and accelerated forward speeds and routes along an artificial straight track of the storm. The results were analyzed to determine the characteristics of the storm surge in terms of forward speed. Some of these were compared with actual cases. Based on the model results, it was found that the forward speed of the storm was inversely proportional to the duration of the storm, and their ratios produced different forms of storm surges. When the forward speed decreases, a storm surge is induced for a longer time. The results also showed that the maximum storm surge increased as the forward speed increased.

Kim, H.; Kim, Y.H.; Oh, S.M.; Kang, K., and Kim, K.O., 2021. Application of data assimilation for spectral wave model in coastal regions of South Korea. In: Lee, J.L.; Suh, K.-S.; Lee, B.; Shin, S., and Lee, J. (eds.), Crisis and Integrated Management for Coastal and Marine Safety. Journal of Coastal Research, Special Issue No. 114, pp. 76–80. Coconut Creek (Florida), ISSN 0749-0208.

The primary factor determining the accuracy of wave simulation is the accuracy of the wind data, which represents the main force of wave generation. Its accuracy also depends on the optimality of parameters related to the growth, dissipation of wave energy and nonlinear energy transfer between wave components. Wave models have limitations due to errors of wind fields and a lack of understanding of wave dynamics such as white capping dissipation, wave-bottom interaction processes and long-term wave propagation. This paper investigates the performance of a wave model based on WAVEWATCH III (WW3) version 6.07 equipped with spectral wave data assimilation using the optimal interpolation (OI) method, which updates the spectral wave energy of the model by assimilating the observed significant wave height. Data assimilation was applied for the coastal region of Korea using near real-time global satellite wave observation data provided by the Copernicus Marine Environment Monitoring Service (CMEMS) and the buoy data of the Korea Meteorological Administration (KMA). The verification of the model was done by comparing simulated results with observations by KMA buoys, which suggests the successful application of the data assimilation to improve the model accuracy.

Kim, I.-C.; Park, K., and Kang, T.-W., 2021. Experimental study on hydraulic performance of tiecell caisson breakwater with wave chamber. In: Lee, J.L.; Suh, K.-S.; Lee, B.; Shin, S., and Lee, J. (eds.), Crisis and Integrated Management for Coastal and Marine Safety. Journal of Coastal Research, Special Issue No. 114, pp. 81–85. Coconut Creek (Florida), ISSN 0749-0208.

Recently, a perforated caisson breakwater with tiecell blocks was developed to improve a water affinity and people's safety of a rubble mound armoured by tetrapods. In this study, hydraulic model tests were performed to examine the hydraulic performance of a non-porous and a tiecell caissons with perforated blocks attacking wave against a small fishery harbor near Busan. The model test results show that the tiecell caisson is more effective in dissipating wave energy under normal wave conditions and in reducing wave overtopping rates under design wave conditions than the non-porous caisson. It is found that the horizontal wave forces acting on the tiecell caisson show slightly more large than the non-porous caisson due to the impulsive force generated in the wave chamber.

Kim, H.; Lee, J., and Kim, Y., 2021. Tidal creek mapping from airborne LiDAR data using multi-resolution cloth simulation filtering. In: Lee, J.L.; Suh, K.-S.; Lee, B.; Shin, S., and Lee, J. (eds.), Crisis and Integrated Management for Coastal and Marine Safety. Journal of Coastal Research, Special Issue No. 114, pp. 86–90. Coconut Creek (Florida), ISSN 0749-0208.

Tidal creeks are transitional waterways promoting the evolution and expansion of tidal flats. The precise and objective delineation of tidal creeks is critical for monitoring the characteristics, formation, and evolution of tidal flats. Airborne light detection and ranging (LiDAR) data are the most widely used source of tidal topography information, since they can provide precise terrain information over wide areas. However, existing tidal creek extraction methods using airborne LiDAR data have limitations, such as the necessity of excessive user intervention and a lack of adaptability to the various shapes and widths of tidal creeks. The morphological irregularities, complexity, and diverse widths (from a few centimeters to several kilometers) of tidal creeks, complicates their automatic or manual extraction from LiDAR data. In this study, we propose an effective and practical method for the mapping of tidal creeks with a wide range of widths. Here, cloth simulation filtering (CSF), a verified ground filtering technique used to filter off-ground objects from point cloud in land LiDAR surveys, was adopted and modified. By sequentially filtering the creek points through a hypothetical cloth with an increasingly larger grid resolution, the proposed multi-resolution CSF can extract huge tidal creeks without compromising the details of narrow creeks. This sequential filtering is based on local thresholds calculated using the creek points extracted during the previous filtering and does not require empirical parameter adjustments. The results of an experimental evaluation based on airborne LiDAR data collected over the west coast of South Korea indicate that the accuracy of the proposed method is high (Kappa > 0.8) and superior to that of results obtained through an user parameter.

Kim, K.O.; Jung, K.T., and Ha, T.M., 2021. Development of a tsunami-tide interaction model with simulation of tsunami wave propagation to Korea coasts. In: Lee, J.L.; Suh, K.-S.; Lee, B.; Shin, S., and Lee, J. (eds.), Crisis and Integrated Management for Coastal and Marine Safety. Journal of Coastal Research, Special Issue No. 114, pp. 91–95. Coconut Creek (Florida), ISSN 0749-0208.

Simulation studies of historic and prognostic tsunamis have been performed with a focus on tsunami-tide interactions. A modeling system based on the 3D POM (Princeton Ocean Model) has been developed that is composed of a global tsunami model and a regional multinesting tide/tsunami/tsunami-tide interaction model covering the Northwest Pacific region. Propagations of two historic tsunamis, the 2010 Chilean and 2011 Tohoku tsunamis, were simulated to estimate the effects of tsunami-tide interactions by comparing the results from tsunami-only and tsunami simulations with tide simulations. Calculations show that tsunami waves are significantly transformed after traveling a long distance and subsequently affected by the tidal phase. As prognostic tsunami propagation, the Nankai Trough earthquake-induced tsunami wave in Japan was investigated. A series of calculations were performed with a systematic shift of the tsunami occurrence time. The effects of tsunami-tide interactions were examined in terms of local tidal phase changes, focusing on the changes in the first tsunami heights and occurrence times arriving at the selected tidal stations in Korea. The tsunami-tide interaction mostly results in a positive change in the tsunami first peak heights with a maximum change near low tide probably due to the interaction between the tsunami-induced current and tidal current. The water depth increase near high tide advances the arrival of the tsunami first peaks, whereas the water depth decrease near low tide delays the arrival of the tsunami first peaks.

Jeong, Y.H.; Lee, S.Y.; Lee, J.; Lee, T.K., and Lee, W.D., 2021. Characteristics of seawater intrusion in coastal aquifers due to seawater flooding: A numerical study. In: Lee, J.L.; Suh, K.-S.; Lee, B.; Shin, S., and Lee, J. (eds.), Crisis and Integrated Management for Coastal and Marine Safety. Journal of Coastal Research, Special Issue No. 114, pp. 96–100. Coconut Creek (Florida), ISSN 0749-0208.

In typical coastal aquifers, dense brine infiltrates under freshwater in a wedge form. However, during seawater flooding due to storm surges or tsunamis, dense brine infiltrates from the surface into the ground. In this study, to investigate the characteristics of seawater intrusion in coastal aquifers. we simulated seawater intrusion by seawater flooding using the Navier–Stokes solver based on the porous body model. The numerical analysis results showed that when the hydraulic gradient of the coastal aquifers was small, salt diffusion by seawater flooding occurred throughout the groundwater, and the infiltrated seawater remained in the freshwater layer for a long time. However, when the hydraulic gradient of the coastal aquifers was large, the salt damage by seawater flooding was relatively small, and the amount of infiltrated seawater that escaped into the sea through the groundwater flow increased. In other words, a larger hydraulic gradient of coastal aquifers leads to a lower salt diffusion in the groundwater by seawater flooding and a faster recovery. The results of this study will be useful for the preservation of coastal aquifers in the event of tsunamis and flooding.

Kim, S.W., and Lee, S.D., 2021. Unsteady flow characteristics at gate of overtopping-type submerged breakwater. In: Lee, J.L.; Suh, K.-S.; Lee, B.; Shin, S., and Lee, J. (eds.), Crisis and Integrated Management for Coastal and Marine Safety. Journal of Coastal Research, Special Issue No. 114, pp. 101–105. Coconut Creek (Florida), ISSN 0749-0208.

In this study, through physical model test and numerical modeling for the unsteady flow of the OSB structure, the discharge/velocity characteristics at the openings were reviewed. During the regular waves propagation with a wave height of 2.0 m and a period of 8.0 s, the flow velocity at the opening (x= 0.25 m) was estimated using the water level information on the front and rear of the opening and the empirical equation for the flow rate of the rectangular weir. The discharge velocity estimated from the empirical equation is slightly underestimated, but the overall variations of flow velocity are well reproduced. From these results, it was confirmed that the return of fluid from the opening to the offshore, which contributes to the improvement of OSB performance, occurs due to the difference in water level front and rear of the opening. There is no direct influence of the wave. These facts are planned to be utilized in the study of structure optimization to use the OSB structure as a wave energy converter while at the same time playing the role of submerged breakwater.

Youn, S.; Jung, B., and Lee, S., 2021. Limited installation ranges of silt curtain in ocean and river hydrodynamic environment. In: Lee, J.L.; Suh, K.-S.; Lee, B.; Shin, S., and Lee, J. (eds.), Crisis and Integrated Management for Coastal and Marine Safety. Journal of Coastal Research, Special Issue No. 114, pp. 106–110. Coconut Creek (Florida), ISSN 0749-0208.

A silt curtain is a flexible ocean structure and is applied to control the diffusion of suspended sediment and pollution materials in the whole world. Specially, the silt curtain is the rational method to control the diffusion of suspended sediment and pollution materials in most ocean construction fields in Republic of Korea. However, this flexible ocean structure has the limitation to install and to maintain in rough hydrodynamic condition due to wave, tidal current, and wind. In this study, the limitation of installation range of silt curtain in countries, where have the rule of installation guide of silt curtain, were reviewed to decide available installation of silt curtain. Designing methods of silt curtain were also reviewed. The applied designing methods in this study were studied in ‘Research to increase the effectiveness of silt curtain (2018)’. To check designing methods, various wave, tidal current, and wind conditions were applied based on designing methods. When tidal current and wave height are over the specific wave height and the speed of tidal current, no more installation of silt curtain was available to use from the result of this study. According to the result, the installation range of silt curtain due to hydrodynamic forces in Republic of Korea is required for safety and protection of ocean environment around maritime area.

Kim, D.-H.; Ryu, H.-R.; Yang, S.-H., and Hwang, K.-N., 2021. Measurement of erosional parameters using ASERA, Automated Sediment Erosion Rate Apparatus. In: Lee, J.L.; Suh, K.-S.; Lee, B.; Shin, S., and Lee, J. (eds.), Crisis and Integrated Management for Coastal and Marine Safety. Journal of Coastal Research, Special Issue No. 114, pp. 111 –115. Coconut Creek (Florida), ISSN 0749-0208.

The stability of tidal flats along the west coast of Korea is a matter of national interest due to their significant role as a protector of the shoreline against erosion by storm surge and waves. Depending on the locations of these flats, their materials range from gravel to clay and their stabilities against currents and waves are highly sensitive to material properties. Stability parameters of immediate interest are the critical shear stress and the sediment load for coarse particles and the shear strength against erosion as well as erosion flux for cohesive sediment. Since in situ determination of these parameters is cumbersome during storm events, it is customary to collect cores of the top layer and analyze them in the laboratory under simulated severe flows. To that end, in recent years the Automated Sediment Erosion Rate Apparatus (ASERA) has been developed. The apparatus consists of a rectangular duct through which water erodes the surface of the bed extruded from a practically undisturbed core at a controlled rate. Also, it is equipped with a laser system along with a high-quality CCD camera for accuracy and consistency in the detection and tracking of the eroding bed. In this study, the ASERA has been evaluated on a preliminary basis through a series of tests to verify its effectiveness with coarse and cohesive sediments. Fifteen coarse sediments ranging from very-fine gravel to very-fine sand were used to determine the critical shear stress and the sediment load. For cohesive sediment the bed shear strength and the erosion flux of uniform density bed of commercial clays were measured. The results for both types of sediment yielded values consistent with the available data and formulas, and it indicates that ASERA has a promising potential for the characterizing mudflat sediments.

Min, E.-H. and Koo, W., 2021. Numerical analysis of nonlinear wave characteristics under porous sloped-seabed conditions. In: Lee, J.L.; Suh, K.-S.; Lee, B.; Shin, S., and Lee, J. (eds.), Crisis and Integrated Management for Coastal and Marine Safety. Journal of Coastal Research, Special Issue No. 114, pp. 116–120. Coconut Creek (Florida), ISSN 0749-0208.

The characteristics of nonlinear wave attenuation were analyzed under porous sloped-seabed conditions. Nonlinear wave propagation was simulated in the time domain using a two-dimensional fully nonlinear numerical wave tank (NWT). The NWT technique was based on the boundary element method and consisted of two computational domains: A fluid domain and a porous seabed domain. To account for the wave-porous subsea interaction, the boundary value problem was solved in each domain, and the calculated values were exchanged at the interface boundary between the fluid domain and the porous domain at each time step. The shoaling coefficients for wave propagation on a sloped-seabed were calculated, and the attenuation of the waves due to interaction with the porous bottom was investigated. Waves traveling to the coast were decomposed into each frequency component, and the magnitude of the wave attenuation ratio for each component was compared. The characteristics of wave propagation according to the permeability coefficients on the seabed, wave steepness, and wave periods were also investigated.

Kim, Y.-J.; Kim, T.-W.; Yoon, J.-S.; Hur, D.-S, and Kim, M.-K., 2021. Shoreline change prediction for integrated coastal erosion management. In: Lee, J.L.; Suh, K.-S.; Lee, B.; Shin, S., and Lee, J. (eds.), Crisis and Integrated Management for Coastal and Marine Safety. Journal of Coastal Research, Special Issue No. 114, pp. 121–125. Coconut Creek (Florida), ISSN 0749-0208.

The mechanism of sediment transport occurring in littoral zone shows complex patterns. Establishing an accurate longshore sediment budget prediction is difficult. Littoral drift flowing into and out of the coast shows sensitive responses to natural and anthropogenic changes in the surrounding area. In particular, at the coast where rivers are located, the littoral drift is significantly affected by the inflow of sediment from the upstream. However, the sediment management at the coast has been conducted by respective measures established in different areas, such as mountains in the upstream region, dams, rivers, and coasts, and thus, measures are established without an appropriate feedback between these different areas. Therefore, determining the exact causes of erosion occurring in the coastal zone is challenging. In addition, for accurate prediction of sediment budget in coastal areas, it is necessary to construct a model with mixed particle size distribution that can consider the properties of sediment inflow from the river and the sediment constituting the sea area. Thus, for integrated coastal erosion management, based on the determination of sediment transport mechanism flowing into the coastal zone, accurate estimation of sediment transport rate and sediment budget prediction according to the shoreline changes affected by waves play an important role.

In this study, a series of mechanism of sediment transport flowing into the sea area through the river was analyzed, and the sediment budget according to the shoreline change occurring in the sea area was estimated. The sediment load flowing into the sea area and the representative wave acting on the sea area were calculated to construct the IN-MPS (INje-Mixture Particle Shoreline) model considering the sediment particle size distribution in mixed condition. The accuracy of the model was evaluated by comparing the results obtained from the model with those of long-term observations by calculating the exact sediment budget in the coastal zone, and when the inflow from the river and the mixed particle size distribution of sediment were considered, the accuracy in the shoreline change prediction was improved.

Jang, J.; Jang, J.; Barbato, M.; Gutierrez-Wing, M.T.; Rusch, K.A., and Jung, J., 2021. Effects of fluorogypsum and quicklime on unconfined compressive strength of Kaolinite. In: Lee, J.L.; Suh, K.-S.; Lee, B.; Shin, S., and Lee, J. (eds.), Crisis and Integrated Management for Coastal and Marine Safety. Journal of Coastal Research, Special Issue No. 114, pp. 126–130. Coconut Creek (Florida), ISSN 0749-0208.

Coastal areas have environmentally and economically important roles but tend have weak soft ground, which is often vulnerable by waves and unsuitable for coastal construction, such as ports and waterfront areas. Hence, this soft ground, which usually contains large amounts of clays, needs to be ameliorated by using appropriate soil improvement techniques. A common approach to improve soft ground is soil–binder injection techniques to enhance its strength. When avaialbe, binders from industrial wastes can be used instead of commercial products, such as cement and lime, to reduce construction costs and minimize environmental disturbance. Reusing industrial wastes mitigates environmental pollution and reduces the costs of waste management. Construction materials, such as sand and cement, can be partially replaced with industrial wastes if the wastes are granular and induce cementation effects. Fluorogypsum (FG), a by-product obtained during the production of hydrofluoric acid, satisfies these conditions, as it is capable of binding granular materials. Approximately 894,000 metric tons are annually produced in the U.S. However, data on the mechanical strength of clay–FG mixtures are unavailable. In this study, we conducted unconfined compressive strength tests to investigate the mechanical behavior of kaolinite, which represented clay in soft ground, at different FG and quicklime contents. The effects of FG on the compressive strength of kaolinite–FG–quicklime mixtures depend on the curing time and weight ratios of the constituent materials. The composition of the mixture with the highest compressive strength was 30% FG, 5% lime, and 65% kaolinite. We infer that the stoichiometric ratios of mixtures control the chemical reactions for the maximum compressive strength at different quicklime contents based on a series of compressive tests.

Park, J.; You, J.; Park, S.-K.; Ryu, S.-C., and Hong, S., 2021. Characterization of application methods for textile-based composite structures in coastal environments. In: Lee, J.L.; Suh, K.-S.; Lee, B.; Shin, S., and Lee, J. (eds.), Crisis and Integrated Management for Coastal and Marine Safety. Journal of Coastal Research, Special Issue No. 114, pp. 131-135. Coconut Creek (Florida), ISSN 0749-0208.

Textiles exhibit many advantages including high strength/weight ratio and high corrosion resistance. Therefore, textiles can substitute steels in textile-reinforced concrete (TRC) and can strengthen existing RC structures, such as textile-reinforced mortar (TRM), in coastal environments. However, there is a difference in the structural performance of TRC and TRM so that it is important to clearly distinguish the behavior of textile-based composites. In this study, the flexural performance, serviceability, ductility, and fabrication process of TRC and TRM were analyzed and compared via two separate application. The results of the experiments were expressed as indexes, which were compared with that of the reference RC specimen. Finally, an efficient method for applying textile-based composite structures in a coastal environment was considered in terms of flexural strength, serviceability, ductility, and fabrication process. The TRM composite exhibited unstable behavior after the yield stage. The TRC composite exhibited stable behavior in all the loading stages and showed higher ductility than that of the TRM composites. The results of this study are expected to aid in the selection of an appropriate application method for conducting intensive durability verification.

Kang, S.K.; Foreman, M.G.G.; Kim, K.O.; Kim, E.J.; Kim, H.; Kang, H.W.; Kim, E.; Lee, S., and Jung, K.T., 2021. Numerical modeling of tide and tide-induced drifting of particles released from the sunken ship in the southeastern Yellow Sea. In: Lee, J.L.; Suh, K.-S.; Lee, B.; Shin, S., and Lee, J. (eds.), Crisis and Integrated Management for Coastal and Marine Safety. Journal of Coastal Research, Special Issue No. 114, pp. 136–140. Coconut Creek (Florida), ISSN 0749-0208.

Drifting analysis of casualties released from a ship accidentally sunken in coastal sea regions off the southwestern tip of the Korean peninsula on April 16, 2014, showed a particular trend of northward drifting. To understand how this takes place and to examine tidal and residual current features in the region, a fine grid tidal modeling has been carried out in this sub-region of the southeastern Yellow Sea. Examination of the phase and sea level slope differences in several waterways of the modeled area suggests that there are noticeable differences in the dominant M2 tidal current speed. It is shown that the M2-driven tidal residual currents are dominant particularly with the prevalence of the northward residual currents near the sunken ship area. A particle trajectory modeling was performed and its accuracy was validated by showing that the locations of 3 casualties (among 300 persons) found outside the sunken ship off the southwestern tip of the Korean peninsula on April 16, 2014, were within the model-predicted area. It was found that the general northward scattering pattern of continuously released particles for 15 days is likely to result from the M2-driven residual currents in this region.

Ryu, H.-R.; Kim, S.-S.; Kim, D.-H.; Jang, W.-S., and Lee, S.-O., 2021. EOF analysis for wind-driven along and cross shelf exchange around a sandbank over the Daesan inner shelf (Yellow Sea, Korea). In: Lee, J.L.; Suh, K.-S.; Lee, B.; Shin, S., and Lee, J. (eds.), Crisis and Integrated Management for Coastal and Marine Safety. Journal of Coastal Research, Special Issue No. 114, pp. 141–145. Coconut Creek (Florida), ISSN 0749-0208.

It is essential to understand the shelf circulation dynamics qualitatively and, if possible quantitively, since the inner shelf is an important zone located between the surf zone and the continental shelf in terms of the heat exchange, the transport of terrigenous sediment, and so on. In this study, from the compound results of current velocity profiles measured by the moored ADCP and wind observations obtained by KMA (Korea Meteorological Administration) over the Daesan inner shelf located in Yellow Sea, Korea, we found that the inner shelf circulation was mainly driven by a combination of wind stress, pressure gradient, Coriolis force and submarine topography. The Empirical Orthogonal Function (EOF) analysis was used to comprehend the shelf circulation dynamics induced by the wind stress and the wavelet coherence was used to analyze the time-frequency distribution of the coherence between currents, which was reconstructed by EOF method and shelf-aligned winds. The thickness of the surface and bottom frictional layers mainly depended on wind forcing and seabed topography. Also, it was found that the subtidal currents were strongly dominated along-shelf due to the irregular seabed topography such as a sandbank. The vertical structure of the along-shelf currents was mostly uniform regardless of water depth change. In mode 2 of EOF analysis, it was shown that the cross-shelf currents were polarized into two layers. Mostly wind in the ocean may cause down-welling or up-welling along the direction, however, in the study area, variation of wind induced current and the Ekman layer are not clearly distinguishable. Additionally, it is resulted that the cross-shelf exchange caused by the wind was not significant because of complicated seabed topography including Jangan sandbank and tidal force even though the Ekman depth was changed by the wind forcing in the Daesan inner shelf. From a result of wavelet coherence analysis, the correlation between wind and currents was also insignificant according to shelf-aligned U, V directions and water depths.

Kim, T.-W.; Kim, Y.-J.; Yoon J.-S., and Kim, M.-K., 2021. Changes in power generation at Sihwa Lake Tidal Power Plant with the installation of submerged breakwaters. In: Lee, J.L.; Suh, K.-S.; Lee, B.; Shin, S., and Lee, J. (eds.), Crisis and Integrated Management for Coastal and Marine Safety. Journal of Coastal Research, Special Issue No. 114, pp. 146–150. Coconut Creek (Florida), ISSN 0749-0208.

Tidal power generation uses potential energy generated by vertical movements of the sea level to run a hydro turbine to produce electricity; thus, it is suitable for areas with large differences between tidal waves. The Sihwa Lake Tidal Power Plant situated on the west coast of South Korea is located at the center of the 11.2-km-long Sihwa Seawall. It generates power by using the increased water level in the outer region during ebb, and it discharges the seawater inflow caused by power generation during flood. In this study, the EFDC (Environmental Fluid Dynamics Code model), which can reproduce the operation patterns of the Sihwa sluice gate and considers permeable structures, was applied to predict the effect of changes in seawater flow resulting from the installation of impact reduction facilities on the nearby offshore of the Sihwa Lake Tidal Power Plant. To calculate the amount of power generated using a numerical model, a year-long daily operation record of the tidal power plant in 2013 was analyzed and used as input conditions (sluice gate operation, runoff) of the numerical model. In addition, a relational expression was derived using the data—inner/outer water-level difference (ΔH), hydro turbine water flowrate (Q), and power generated (W)—and the power output was calculated using the inflow rate calculated by the numerical model.

Kim, Y.-T. and Lee, J.-I., 2021. Reflection of irregular waves from perforated-wall structures when the chamber is filled with rocks. In: Lee, J.L.; Suh, K.-S.; Lee, B.; Shin, S., and Lee, J. (eds.), Crisis and Integrated Management for Coastal and Marine Safety. Journal of Coastal Research, Special Issue No. 114, pp. 151–155. Coconut Creek (Florida), ISSN 0749-0208.

The perforated-wall is normally applied to the quay walls and breakwaters such as vertical structures to improve the hydraulic characteristics. The perforated-wall could reduce the wave reflection, wave pressure, and wave overtopping comparing with the plane wall. The chamber of perforated-wall was generally designed empty, that is, the chambers were filled with only seawater. In this study, the hydraulic characteristics of perforated-wall were investigated with hydraulic model experiments when the chambers were filled with the armor rocks. The perforated-wall with vertical slits was applied in the tests. The numbers of the chamber and the sizes of the armor rock were changed. The reflection from the perforated wall was measured and compared for the various test conditions.

Lee, D.; Park, H.; Shin, S., and Cox, D.T., 2021. Experimental and numerical study on the wave, surge, and structure interactions on a coastal residential building. In: Lee, J.L.; Suh, K.-S.; Lee, B.; Shin, S., and Lee, J. (eds.), Crisis and Integrated Management for Coastal and Marine Safety. Journal of Coastal Research, Special Issue No. 114, pp. 156–160. Coconut Creek (Florida), ISSN 0749-0208.

Residential structures in the low-lying coastal region are often suffered from devastate coastal disasters, like storms and tsunamis. To minimize the loss and improve the resilience of a coastal community, it is crucial to understand structural damage and failure mechanism under extreme from extreme coastal events. Large-scale laboratory experiments of wood-framed residential houses were conducted to investigate the wave and surge effect on the structure and the structural failure mechanism. The tests were conducted by changing a surge level, wave period, and wave height condition, and measure hydro-kinematics and structural damage process. LIDAR scanning was conducted to collect the data of damage proportion on the structure during series of wave and surge conditions. A three-dimensional RANS model, olaFlow, was used to verify our numerical model, and applied to understand hydrodynamics near the structure. Three different wave breaking conditions, including non-breaking, breaking, and broken wave are tested and consequent wave induced forces on structure are compared for both undamaged structure and damaged structure conditions. The numerical model results showed a good agreement with the experimental results in water surface and velocity. The numerical results of wave induced force in damaged conditions showed 28∼43% smaller than those in undamaged conditions. This finding highlight that the damage level of a structure could affect predicting wave load on the structure.

Yoo, H.J.; Kim, D.H.; Park, M.H., and Lee, S.O., 2021. Economic sediment transport control with sediment flushing curves for sea dike gate operation: Case study in Saemangeum Basin, Korea. In: Lee, J.L.; Suh, K.-S.; Lee, B.; Shin, S., and Lee, J. (eds.), Crisis and Integrated Management for Coastal and Marine Safety. Journal of Coastal Research, Special Issue No. 114, pp. 161–165. Coconut Creek (Florida), ISSN 0749-0208.

As the major reclamation works in Korea, the sea dikes have been installed for preventing the saltwater intrusion in Saemangeum Basin connected with Mangyeonggang and Dongjingang River, Korea since 2010. Recently, the sedimentation issues near the gates due to change of flow velocity might induce serious problems such as water pollution, local scour, stability of hydraulic structures linked with dike. We focused that the gate operation rule was changed to alleviate the sediment transport problem by altering the management water surface elevation in this study. The 3D numerical model, SCHISM, was used to simulate the sediment transport under the gate operation rule which was embedded after modifying the hydraulics structure module in SCHISM. The numerical model was verified by comparing with the measured data in the literature. It was found that the phenomenon induced by gate operation was accurately simulated to compare with the field measurements from Korea Rural Community Corporation (KRCC). Based on the results of SCHISM, the Best Management Practices on gate operation were examined and suggested the optimal solution in terms of structural stability and water use including water quality.

Wurjanto, A. and Mukhti, J.A., 2021. Hydraulic treatise of untreated water reservoir design of Indonesia's national capital integrated coastal development offshore dike. In: Lee, J.L.; Suh, K.-S.; Lee, B.; Shin, S., and Lee, J. (eds.), Crisis and Integrated Management for Coastal and Marine Safety. Journal of Coastal Research, Special Issue No. 114, pp. 166–170. Coconut Creek (Florida), ISSN 0749-0208.

Coastal flooding and land subsidence are among the main issues for cities along the northern coast of Java Island. The Indonesian government planned to build integrated coastal protection along the northern coast. For the Capital City of Jakarta, the offshore dike will be complemented with a coastal reservoir to store freshwater for municipal uses. To overcome the occasional extreme weather, an untreated water reservoir (UWR) is required. This paper discussed the design of UWR pumping capacity and flood gate design of capital offshore dike through a hydrodynamic analysis with Delft3D. Flood hydrographs of extreme rainfall were created based on the data provided by the Ministry of National Planning. Bathymetry and tidal source were collected from GEBCO and NAOTide respectively. Hydrodynamic modeling was performed with variations on pump capacity and river input flows. The hydrodynamic model shows that the current UWR design can hold up to a 10-year flood without pumping. For more extreme floods, the UWR can also retain the water below the high water level with the help of pumps. The water elevation can be back to normal at -5.0 mLWS within a day of pumping with 1,600 m³/s.

Lim, H.S.; Kim, D.; Lee, H.J.; Kim, M.; Jin, S.H.; Miles, T.N., and Glenn, S., 2021. Typhoon-induced full vertical mixing and subsequent intrusion of Yangtze fresh waters in the Southern Yellow Sea: Observation with an underwater glider and GOCI ocean color imagery. In: Lee, J.L.; Suh, K.-S.; Lee, B.; Shin, S., and Lee, J. (eds.), Crisis and Integrated Management for Coastal and Marine Safety. Journal of Coastal Research, Special Issue No. 114, pp. 171–175. Coconut Creek (Florida), ISSN 0749-0208.

Typhoons have been regarded as an important forcing to control oceanographic phenomena, particularly in the Yellow and East China Seas. The influences of typhoons have become increasingly severe due to global warming. An autonomous underwater glider was deployed west of Jeju Island for 10 days from 15th to 25th August, 2018 to observe changes in physical environments induced by Typhoon Soulik. The glider data show that the stratified water masses were destroyed by the typhoon into a fully mixed stage of the entire water column. This destratification is manifested by many environmental parameters including temperature, salinity, chlorophyll-a, and suspended sediment concentrations. Accordingly, calculated parameters, density, and Richardson number, indicate de-stratification. The water column displayed, however, a rapid return to the stratification stage immediately after the typhoon passage. In addition, the GOCI geostationary ocean color imagery was analyzed that were obtained during and after the passage of Soulik between 15-25 August, 2018. These satellite images suggest that the discharge of the Yangtze River fresh water so increased during the typhoon that the intensified freshwater plume could move toward Jeju Island. As a result, observations with an autonomous glider may provide a promising means in analyzing oceanographic processes occurring during the peak of typhoons.

Araki, S.; Kotake, Y.; Kubota, S.-I.; Shibutani, Y.; Kawauchi, Y., and Yamamoto, F., 2021. Wave overtopping rate on vertical seawall with deformed wave dissipating work. In: Lee, J.L.; Suh, K.-S.; Lee, B.; Shin, S., and Lee, J. (eds.), Crisis and Integrated Management for Coastal and Marine Safety. Journal of Coastal Research, Special Issue No. 114, pp. 176–180. Coconut Creek (Florida), ISSN 0749-0208.

This paper describes the variation in wave overtopping rate with deformation of wave dissipating work. Slight deformation of wave dissipating work is expected to cause no significant increase in wave overtopping rate. A series of hydraulic experiment was conducted to measure the wave overtopping rate at a vertical seawall with deformed wave dissipating work. The experiment shows that the deformation of wave dissipating work does not necessarily cause a drastic increase in the wave overtopping rate. Although a procedure for estimating the wave overtopping rate is proposed, the results show that the procedure needs to be improved.

Kim, H.-J.; Cho, W.C., and Moon, Y.-H., 2021. Comparative analysis on wave field using wave measurement and wave analysis data from JMA-MSM. In: Lee, J.L.; Suh, K.-S.; Lee, B.; Shin, S., and Lee, J. (eds.), Crisis and Integrated Management for Coastal and Marine Safety. Journal of Coastal Research, Special Issue No. 114, pp. 181–185. Coconut Creek (Florida), ISSN 0749-0208.

Waves are the most important factor in the numerical analysis of coastal hydrodynamics. Wave conditions in coastal areas can be determined in on-site wave measurements or wave numerical analyses. Because the acquisition of spatial wave measurement data in a specific coastal area is limited, the spatial wave data are generally acquired with accurate numerical analyses.

In this study, the wave field in a coastal area in South Korea was comparatively analyzed with wave measurements and numerical analyses of wind data acquired with the JMA (Japan Meteorological Agency) Meso-Scale Model (MSM). The high-resolution meteorological data were used for the numerical analysis, and the wave measurement data provided by the Wave Information Network of Korea (WINK) were used for the comparative analysis. Results showed the root mean square errors of 0.3-0.4m for all wave prediction in the East Sea in 2018 and 0.4-0.5m for typhoon KONG-REY in 2018. Therefore, it was concluded that the wave numerical simulations based on the wave data from JMA-MSM overall reproduced the wave field accurately.

Jung, M.-K.; Kim, J.-Y.; Lee, B., and Kwon, H.-H., 2021. Exploring the combined risk of sea level rise and storm surges using a Bayesian network model: Application to Saemangeum seawall. In: Lee, J.L.; Suh, K.-S.; Lee, B.; Shin, S., and Lee, J. (eds.), Crisis and Integrated Management for Coastal and Marine Safety. Journal of Coastal Research, Special Issue No. 114, pp. 186–190. Coconut Creek (Florida), ISSN 0749-0208.

In terms of natural hazards, typhoon-induced storm surge along with heavy rainfall has been recognized as the most frequently reported hazard among water-related disasters in the coastal areas in South Korea. Moreover, it has been widely acknowledged that the frequency and intensity of typhoons (or abnormal low-pressure systems) are likely to increase over time due to the potential impact of climate change. A risk analysis covering different loading conditions has been a tool for flood risk management in these contexts. We propose a Bayesian network-based generic risk analysis tool for flood defense systems such as a levee, dike, and seawall. On the other hand, this study explores various failure modes of flood defense structures for the use of risk analysis. In this study, the proposed modeling framework is applied to Saemangeum seawall in South Korea. Based on the literature review, various failure modes for Saemangeum seawall was identified, and the selected failure mode is then translated into nodes in the Bayesian network framework. The failure probability was estimated quantitatively by computing the limit state equation, which is composed of a set of random variables. Moreover, we investigated a Bayesian network model to assess the impact of compounding risk associated with revetment erosion of the seawall from sea-level rise informed by climate change scenarios. A further discussion on the role of the uncertainty for overall risk is provided.

Kim, Y.-T.; Uranchimeg, S.; Park, M.H., and Kwon, H.-H., 2021. Predictability of coastal extreme wave heights based on a nonstationary hierarchical Bayesian model: The role of the sea surface temperature. In: Lee, J.L.; Suh, K.-S.; Lee, B.; Shin, S., and Lee, J. (eds.), Crisis and Integrated Management for Coastal and Marine Safety. Journal of Coastal Research, Special Issue No. 114, pp. 191–195. Coconut Creek (Florida), ISSN 0749-0208.

The increasing frequency of extreme wave heights has been observed in many parts of the world due to recent global warming. Especially, the variability of extreme wave heights in the summer season has increased during the last three decades over the coast of South Korea that is partially attributable to the increase of the climate variability, leading to the changes in frequency and intensity of the extreme wave heights. Further, coastal areas are particularly vulnerable to the increased climate variability, and the associated risk can be exacerbated by the rapid coastal development over South Korea. Most of the extreme wave heights in South Korea are largely caused by a typhoon during the summer season. Recent studies revealed that the typhoon frequency and intensity in the Asian monsoon region are modulated by Sea Surface Temperature (SST) during the summer season from May to November. Traditional frequency analysis methods do not consider the year to year shifts in wave heights risk distributions that are attributed to changes in climate variability that affect the causal structure of coastal inundation risk. In this perspective, a climate-informed nonstationary frequency analysis model is proposed to predict the extreme wave heights and explore the role of the SST in a Bayesian regression framework. The parameters of the nonstationary frequency model are obtained using a Markov Chain Monte Carlo algorithm. The proposed model shows strong potential for predicting the extreme wave heights by linking large-scale climate patterns, providing motivation for developing dynamic coastal flood risk management strategies.

Kim, H.-J.; Kim, Y.-T.; Kim, T.-W., and Kwon, H.-H., 2021. A nonstationary wind speed frequency model over South Korea: In the context of Bayesian mixture distribution model. In: Lee, J.L.; Suh, K.-S.; Lee, B.; Shin, S., and Lee, J. (eds.), Crisis and Integrated Management for Coastal and Marine Safety. Journal of Coastal Research, Special Issue No. 114, pp. 196–200. Coconut Creek (Florida), ISSN 0749-0208.

It has been well recognized that extreme wind speed processes often feature nonstationary behavior, which may not be effectively modeled within a stationary frequency modeling framework. Furthermore, univariate Gumbel distribution has been commonly used for wind speed frequency analysis in Korea. However, the distributional changes in extreme wind speed have been globally observed, including Korea. More specifically, the univariate Gumbel distribution based wind speed frequency analysis often failed to describe multimodal behaviors which are mainly influenced by distinct climate conditions. In this perspective, this study explores a mixture distribution based nonstationary frequency (MDNF) model in a changing climate within a Bayesian framework. It was found that the MDNF model can effectively account for the time-varying moments (i.e., mean and variance) in a two-component mixture distribution. The MDNF model showed more robust results for describing the upper tail of the distribution, which plays a crucial role in estimating the design wind speed.

Nam, J.; Hong, S.; Lee, Y., and Kim, I., 2021. Correlation analysis between color and grain size of sand using a colorimeter. In: Lee, J.L.; Suh, K.-S.; Lee, B.; Shin, S., and Lee, J. (eds.), Crisis and Integrated Management for Coastal and Marine Safety. Journal of Coastal Research, Special Issue No. 114, pp. 201–205. Coconut Creek (Florida), ISSN 0749-0208.

To determine the cause of coastline changes, it is necessary to monitor various parameters such as wave data, changes in water depth, seabed topography and quality, as well as sea currents. This study aims to derive a correlation between grain size and color of sand on a coast undergoing erosion in Namae 3-ri∼Sodol beach. Therefore, for a period of six years (2013 to 2018), the depths of the foam zone, the breaking band, and other factors were divided for each cross-base line (DL(±) 0.00 m, DL(-) 3.00 m, DL(-) 6.00 m, and DL(-) 9.00 m). Seabed samples were collected from four vertices, and the median particle size and color characteristics of sand were recorded. Results showed that the average D₅₀ particle sizes for DL(±) 0.00 m, DL(-) 3.00 m, DL(-) 6.00 m, and DL(-) 9.00 m were 0.615 mm, 0.432 mm, 0.416 mm, and 0.410 mm, respectively. In addition, the color of the sand that was passed through the colorimeter is represented by L* (white-black), a* (green-red), and b* (yellow-blue); these colors were expressed as a number to present a unique value. DL(±) 0.00 m = L* 61.12082, a* 5.757663, b* 17.93326; DL(-) 3.00 m = L* 61.81803, a* 5.03382, b* 16.79151; DL(-) 6.00 m = L* 61.74719, a* 4.886109, b* 16.54382; and DL(-) 9.00 m = L* 61.70353, a* 4.815222, and b* 16.42189. Furthermore, the sand color values a* and b* were coordinated, distributed on the beach, and then a color range converted to the value of the radius of the polar coordinate (r) was presented and compared with the particle size. To compare the a* and b* values with the sand particle size, r is expressed as a first-order function. The R-square of the first-order function was 0.9411, which was found to be highly reliable, and the exponential function was found to have a reliability of 0.5573. This result shows that the a* and b* values can be inferred according to the particle size of the sand.

Nur, A.A.; Suprijo, T.; Mandang, I.; Radjawane, I.M.; Park, H., and Khadami, F., 2021. Ocean modeling in the Makassar Strait and Balikpapan Bay using online nesting method. In: Lee, J.L.; Suh, K.-S.; Lee, B.; Shin, S., and Lee, J. (eds.), Crisis and Integrated Management for Coastal and Marine Safety. Journal of Coastal Research, Special Issue No. 114, pp. 206–210. Coconut Creek (Florida), ISSN 0749-0208.

This study had applied offline nesting method (one-way interaction) by using Regional Ocean Modeling System (ROMS) to simulate currents circulation in the Balikpapan Bay and showing good results with a high agreement between model output and observational measurement for water level data. It proves that even using the offline nesting method is the better option than increasing grid resolution on the entire model domain that will be demanding more computational cost, while the area of interest is a small-scale application. Therefore, this study aims to improve the model solution by using the online nesting method (two-way interaction) with a refinement ratio of 1:5 from the larger domain to a smaller domain. Three domains which include larger domain (L1) with spatial resolution 2.5 km that encompasses almost the entire Makassar Strait and acted as parent grid for the model. Coarser model of domain L2 with 500 m resolution becomes the buffer zone between the parent model (L1) and smaller domain (L3) in the Balikpapan Bay that has 100 m resolution. Initial and boundary conditions (IC/BC) for the L1 domain consisting of water levels, currents, temperature, and salinity were derived from the Hybrid Coordinate Ocean Model (HyCOM) re-analysis dataset. By using this method, there is only IC needed to be prepared for the other domain by interpolating IC data from the L1 domain and the BC would be provided directly from their larger domain during the simulation. Surface forcing for all domains extracted from the European Centre for Medium-Range Weather Forecast (ECMWF) ERA5 hourly dataset. Statistical methods such as Root Mean Square Error (RMSE) and model skill were used to validate model results for each model domain and found the improvement of the model solution when comparing observational data by model results for the larger and smaller domain at the same location, respectively.

Hur, D.-S.; Lee, W.-D.; Lee, S.-Y., and Jeong, Y.-M., 2021. Experimental study on reduction of water level behind a caisson-type submerged breakwater. In: Lee, J.L.; Suh, K.-S.; Lee, B.; Shin, S., and Lee, J. (eds.), Crisis and Integrated Management for Coastal and Marine Safety. Journal of Coastal Research, Special Issue No. 114, pp. 211–215. Coconut Creek (Florida), ISSN 0749-0208.

In this study, hydraulic model experiments were performed for four types of cross sections depending on the presence or absence of drainage channel of Caisson-Type submerged breakwaters, in which slit-upper-level and lower-level drainage channels are installed to lower the water level behind the submerged breakwaters. Additionally, based on the measured water level data, compared the changes in the average water level behind the submerged breakers for cases with or without drainage channels with a Solid-Caisson that has no slit-upper-level and lower drainage channels. Hence, in submerged breakwaters with a slit-upper-level drainage channel, the rear water level was reduced by 27.1∼52.5% compared to that with Solid-Caisson, and it was reduced by 36.8∼62.2% and 67.4∼81.5%, in the case of lower-level drainage channel and the combined case, respectively. Therefore, lowering of water level behind the submerged breakwaters is better using the lower-level drainage channel than with the slit-upper-level drainage channel. Moreover, its effect is excellent when both are used. The Caisson-Type submerged breakwater proposed herein was found to be effective in reducing the rear water level and the flow in the openings, thereby securing the stability of the submerged breakwaters.

Kim, M.-K.; Kim, T.-W.; Yoon, J.-S., and Kim, Y.-J., 2021. Analysis of storm surge considering waves on the southeastern coast of South Korea. In: Lee, J.L.; Suh, K.-S.; Lee, B.; Shin, S., and Lee, J. (eds.), Crisis and Integrated Management for Coastal and Marine Safety. Journal of Coastal Research, Special Issue No. 114, pp. 216–220. Coconut Creek (Florida), ISSN 0749-0208.

The effects of high waves should be considered to accurately interpret storm surges occurring in coastal areas; however, the general theory is that the rise in water level due to radiation stress would have little impact on the west and south coasts of South Korea because waves tend to be considerably attenuated due to the topographic characteristics of the rias style coast. However, in a study by Mase et al. (2011), the storm surge owing to Typhoon Isewan was predicted; the results obtained indicated that the water level considerably rose due to the effects of waves even in Nagoya Bay, where high waves do not develop due to topographic characteristics. Therefore, the present study aimed to build a storm surge model for the southeastern coast (rias style) of South Korea and to examine the sensitivity of the wave to the rise in water level. By examining the typhoon, a rise in water level due to radiation stress was observed in some areas on the southeastern coast of South Korea. This result suggests the necessity of a storm surge analysis considering the effect of high waves even in areas where they do not develop due to topographic characteristics.

Kim, D.; Shim, J.-S.; Min, Y.; Min, I.K., and Lim, H.S., 2021. Estimation of added mass and radiation damping of large ocean observation buoy using numerical analysis. In: Lee, J.L.; Suh, K.-S.; Lee, B.; Shin, S., and Lee, J. (eds.), Crisis and Integrated Management for Coastal and Marine Safety. Journal of Coastal Research, Special Issue No. 114, pp. 221–225. Coconut Creek (Florida), ISSN 0749-0208.

A vane is to be installed to control the yawing behavior of a large ocean observation buoy (LOOB). The role of the vane is to control the yaw motion of the one-point mooring LOOB against current and waves. The lengths of the vanes were 0.8, 1.6, and 2.0 m, and the added mass tensor (6 × 6) and radiation damping tensor (6 × 6) at that time were estimated using computational fluid dynamics. In addition, the added mass tensor and radiation damping tensor according to the wave frequency domain are presented. Estimating the added mass and radiation damping of LOOB is important because it presents the hydrodynamic relationship between the structure and fluid. As a result of the analysis, the added mass was almost unchanged in other components except m₆₆. On the other hand, m₆₆ was proportional to the length of vane. When the length of the vane is 0.8 m, the maximum added mass is 1.28 × 10⁴ kg (wave frequency 3.7 rad/s), and when the lengths are 1.6 and 2.0 m, it increases to 2.79 × 10⁴ and 3.58 × 10⁴ kg, respectively. This means that the length of the vane affects the resistance to rotational motion. In the case of radiation damping, the results were that the length of the vane and the radiation damping (component c₆₆) were proportional. However, there is no significant difference depending on the length of the vane in the other components (c₁₁ to c₅₅). Radiation damping (c₆₆) increased to 1.12 × 10⁴, 3.56 × 10⁴ and 4.46 × 10⁴ kg, according to the length of the vane. In conclusion, it can be seen that the longer the vane, the better the yaw control effect. However, as the length of the vane increases, the geometric asymmetry of the LOOB increases. In addition, it can be cause fatal damage to small boats berthing the LOOB. Therefore, it is necessary to optimally design it by considering the advantages and disadvantages according to the length of the vane.

Lee, S.-Y.; Kim, D.-H.; Kim, D.-S.; Kim, H.-J.; Jeong, Y.-H.; Hong, S.-J., and Lee, H.-Y., 2021. Applicability of disaster scale criteria for swell-like waves based on wave overtopping predictions. In: Lee, J.L.; Suh, K.-S.; Lee, B.; Shin, S., and Lee, J. (eds.), Crisis and Integrated Management for Coastal and Marine Safety. Journal of Coastal Research, Special Issue No. 114, pp. 226–230. Coconut Creek (Florida), ISSN 0749-0208.

In this study, a wave overtopping prediction system was established for 10 major ports adjacent to 10 testbeds in South Korea, and a qualitative assessment of the system's reproducibility was performed through field surveys. The system estimates the probability of wave overtopping hazards, which is required for responding to disasters caused by swell-like waves. Wave overtopping prediction requires information on artificial structures in the major ports near the testbeds, swell-like wave predictions, and wave overtopping rate calculations. The threshold for defining wave overtopping hazards that can affect the hinterland, facilities, and residents in coastal areas was set to 0.01 m³/s/m, in accordance with EurOtop standards (Pullen et al., 2018) and the Korean Ministry of Oceans and Fisheries. The results of this study can be used to facilitate decision-making by providing qualitative estimations of wave overtopping hazards at various levels. By comparing the results to standard values, the risk of swell-like waves in testbeds along the East Sea coast can be determined. The proposed system can be used to avoid casualties and property damage in the event of a wave-overtopping disaster.

Kim, D.-H.; Yoo, C.-I.; Jeong, Y.-H.; Lee, S.-Y., and Kim, H.-J., 2021. Improvement of numerical simulation using applied statistical properties of directional waves by typhoons. In: Lee, J.L.; Suh, K.-S.; Lee, B.; Shin, S., and Lee, J. (eds.), Crisis and Integrated Management for Coastal and Marine Safety. Journal of Coastal Research, Special Issue No. 114, pp. 231–235. Coconut Creek (Florida), ISSN 0749-0208.

Typhoon-generated wave fields are of importance both scientifically for understanding coastal zone protection and operationally for predicting potentially hazardous conditions for coastal regions. However, the effects of directional wave-to-wave characteristics near bays and estuaries during typhoons are poorly understood due to a strong lack of wave field data. To improve the accuracy of wave height design, this study investigated a highly accurate numerical simulation using the statistical properties of directional waves. Directional wave data were collected using the directional wave recorder MIDAS-DWR, the Geoje and Haeundae floating buoys, and the Gwangan light beacon on typhoons Ma-on and Muifa in July and August, 2011. Moreover, numerical simulation results from STWAVE based on the wave action balance equation were compared with significant wave heights and periods of collected in-situ measurement data. Model input parameters included significant wave height and peak period, as well as wave direction either from wave gauge observations (Case 1) or wave direction statistical properties (Cases 2 and 3). Numerical simulations using the mean and standard deviation of principal wave direction observation data in Mode ± 45° for the largest wave height (Case 3) showed excellent agreement. Results show that wave characteristics can be accurately analyzed using statistical analysis of wave direction rather than actual wave direction inputs, which fluctuates highly in the outer sea. Further, a numerical experiment considering the influence of local wind and flow was performed, showing that the influence of these factors on wave characteristics during typhoons can be studied continuously.

Bahk, J. and Kim, C.W., 2021. Statistical classification of sand beaches in the Taean region and applications for disaster prevention. In: Lee, J.L.; Suh, K.-S.; Lee, B.; Shin, S., and Lee, J. (eds.), Crisis and Integrated Management for Coastal and Marine Safety. Journal of Coastal Research, Special Issue No. 114, pp. 231–235. Coconut Creek (Florida), ISSN 0749–0208.

This study applied cluster analysis and multidimensional scale analysis using nine variables to 20 beaches in South Korea for statistical classification. According to the method of cluster analysis, four clusters were classified, and individual clusters exhibited different characteristics. By plotting the results of cluster analysis as a function of the multidimensional scale analysis, it was confirmed that beaches were mostly appropriately clustered. From the perspective of policymaking and disaster management, beach hazard assessment and oil spill sensitivity of beaches in the Taean region were calculated based on the research results. The study provides insights into the beach classification process and proves that classification using statistical analysis can be used as basic data for policymaking and implementation.

Kim, H.; Moon, C.-J.; Kim, Y.-G.; Chon, K.-H.; Joo, J.Y., and Ryu, G.H., 2021. Analysis of atmospheric stability for the prevention of coastal disasters and the development of efficient coastal renewable energy. In: Lee, J.L.; Suh, K.S.; Lee, B.; Shin, S., and Lee, J. (eds.), Crisis and Integrated Management for Coastal and Marine Safety. Journal of Coastal Research, Special Issue No. 114, pp. 241–245. Coconut Creek (Florida), ISSN 0749–0208.

The ground friction force is lower in coastal and marine areas than it is on land, and there is a relatively high frequency of strong winds in such areas, which substantially affects the life and stability of wind turbines. In particular, the strong wind at the bottom of the atmospheric boundary layer is generated by a combination of thermal and mechanical factors, so there is always a risk due to vertical wind shear and strong turbulent gusts. Therefore, to prevent physical loss of wind turbines located in the atmospheric boundary layer, it is necessary to analyze the wind condition through a more accurate atmospheric stability analysis. In this study, observation data from the Boseong Standard Meteorological Tower are examined to select strong wind cases in the lower atmospheric boundary layer, and the vertical distribution characteristics of the wind resources are analyzed according to the Monin-Obukhov length (MOL). The results confirmed that the vertical wind velocity gradient caused by atmospheric stability mainly changes when the atmosphere is in the near-neutral state at night during the winter.

Ryu, G.H.; Kim, H.; Kim, Y.-G.; Chon, K.-H.; Joo, J.Y., and Moon, C.-J., 2021. GIS-based site analysis of an optimal offshore wind farm for minimizing coastal disasters. In: Lee, J.L.; Suh, K.-S.; Lee, B.; Shin, S., and Lee, J. (eds.), Crisis and Integrated Management for Coastal and Marine Safety. Journal of Coastal Research, Special Issue No. 114, pp. 246–250. Coconut Creek (Florida), ISSN 0749–0208.

The horizontal force transmitted to the turbine and the substructure of a wind power system is very important factor in system safety, and such a system is particularly vulnerable to large-scale coastal disasters such as earthquakes and typhoons. Wind power systems built offshore and on coasts have reduced economic efficiency due to the increase in initial investment costs, because they require a more robust design when installed in areas vulnerable to coastal disasters. The western and southern seas of Korea have a relatively shallow water depth, which is advantageous for the construction of offshore wind farms. However, since it is close to the Pacific Rim, the probability of an earthquake is relatively high compared to those in other regions, and the frequency of typhoons is higher as well, so a more detailed site analysis is necessary. In this study, the GIS technique was used to select an optimal site for wind farms with a focus on reducing the risk of coastal disasters. The current state of earthquakes in the western and southern seas of Korea as well as the movement path and intensity of typhoons affecting or passing through the western and southern seas were also analyzed in a complex manner. As a result, an optimal site for an offshore wind farm with the lowest risk of coastal disasters was analyzed.

Kim, M.-S.; Kim, D.; Eom, H.; You, S.H.; Jeong, J.-S., and Woo, S.-B., 2021. Segmentation of marine forecast zone in Korea by using wave data: Based on k-means clustering algorithm. In: Lee, J.L.; Suh, K.-S.; Lee, B.; Shin, S., and Lee, J. (eds.), Crisis and Integrated Management for Coastal and Marine Safety. Journal of Coastal Research, Special Issue No. 114, pp. 251–255. Coconut Creek (Florida), ISSN 0749-0208.

The Korea Meteorological Administration (KMA) classified the forecast zone based on the administrative districts, weather characteristics, civil complaints, and location of observation points. A cluster analysis was performed using the wave observation and model data to check the validity of the current forecast zone for the wave forecast. The cluster analysis is a method used to group areas with common characteristics. In this study, a set of n objects was decomposed into k clusters (groups) and a distance-based method, k-means clustering algorithm, was used. As the data structure of the cluster analysis, the mean and standard deviation of the significant wave height and wave period during the period of 2014 to 2016 were selected. When performing the cluster analysis with wave heights and wave periods observed at ocean buoys, 11–12 cluster conditions have relatively significant internal evaluation indices suggesting the distance and variance ratio between points and points within each cluster or between distinct clusters. However, since there were few points to perform the segmentation of the marine forecast zone using only the observation data, there was a problem that clusters concentrated in a specific area were distributed. Therefore, it is necessary to perform the cluster analysis by using the KMA wave model for the segmentation of the marine forecast zone. As a result, 10 cluster condition showed the best internal evaluation indices. Although the results of the cluster analysis did not differ significantly from the current forecast zone, the segmentation was made more distinct and detailed.

Youn, D. and Park, Y.H., 2021. Climate change: Characteristics of storms around Korea. In: Lee, J.L.; Suh, K.-S.; Lee, B.; Shin, S., and Lee, J. (eds.), Crisis and Integrated Management for Coastal and Marine Safety. Journal of Coastal Research, Special Issue No. 114, pp. 256–260. Coconut Creek (Florida), ISSN 0749-0208.

Many studies have shown that the intensity and frequency of storms are increasing due to global warming. Because storms are affected by many factors, such as the climate and sea, the relationships of some factors still need to be studied for better understanding. Most recent storm studies have focused on increasing the accuracy of numerical model simulations; however, this study employs statistical methods to find the correlation among factors that determined storm characteristics. Correlation analysis was conducted using certain factors in the ocean and atmosphere. The analysis was conducted using R software for statistical computing of the selected storms passing near the Korean Peninsula, considering the difficulty of storm study. Typhoons occurring in the last 40 years were analyzed, and the relationships of many variables were calculated. The number of typhoons heading for Korea has increased, but the increment of their intensity was not apparent in the observational data. Unlike previous methods, this work was conducted for typhoons that passed through a defined area on the southern coast of the Korean Peninsula. In the region between 30° and 35° N, typhoon paths changed to move northeast instead of being dominated by the Westerlies. Typhoons starting at lower latitudes and more easterly locations tend to develop into strong typhoons, and typhoons starting at lower latitudes tend to be larger.

Sunwoo, W.; Lee, G.; Nguyen, H.H.; Shin, H., and Jun, K.S., 2021. Parameter optimization of a conceptual rainfall-runoff model in the coastal urban region. In: Lee, J.L.; Suh, K.-S.; Lee, B.; Shin, S., and Lee, J. (eds.), Crisis and Integrated Management for Coastal and Marine Safety. Journal of Coastal Research, Special Issue No. 114, pp. 261–265. Coconut Creek (Florida), ISSN 0749-0208.

The rainfall-runoff simulation based on local conditions is crucial for flood monitoring and mitigation. Although numerous rainfall-runoff models were widely used, only few studies have been applied in coastal regions in South Korea. The major reasons are that model parameters are incorrectly determined, and the peak flooding is overestimated due to extreme rainfall events. In this study, a conceptual rainfall-runoff model, the Probability Distributed Model (PDM), was employed to simulate discharge with an incorporation of combined satellite-, model-, and ground-based soil moisture as an input data. The combined soil moisture data was generated using two renormalization strategies. In this study, we aimed to compare the performances of two optimization techniques associated in the PDM model, including a traditional non-linear and a newly metaheuristics algorithms, for the discharge prediction. The simulation was conducted in a coastal urban region, Hongseong, using the optimized parameter sets for flood events. The simulated results from the PDM model revealed that parameters obtained with the metaheuristics algorithm indicated a superior performance when comparing against the observed runoff data. Moreover, parameter sets obtained by the metaheuristics algorithm and non-linear technique showed significant differences. The method of this study can provide more improvements in rainfall-runoff simulation results for flood management.

Kwon, Y.; Kim, J., and Kwon, S., 2021. Analyzing the impact of building wind in coastal areas. In: Lee, J.L.; Suh, K.S.; Lee, B.; Shin, S., and Lee, J. (eds.), Crisis and Integrated Management for Coastal and Marine Safety. Journal of Coastal Research, Special Issue No. 114, pp. 266–270. Coconut Creek (Florida), ISSN 0749-0208.

Building wind causes a large amount of damage in coastal cities, where high-rise buildings are, typically, densely constructed. This paper describes the effects of building wind on coastal cities with a high concentration of highrise buildings under extreme weather conditions such as during typhoons. We performed simulations involving four wind directions (east, west, south, and north) at two sites, i.e., Marine City and LCT, which are well known as representative coastal urban areas in Busan, South Korea, with concentrated areas of high-rise buildings. We used a computational fluid dynamics program; a user-defined function was employed to simulate the wind environment during a typhoon. A contour analysis of the wind velocity indicated that the overall wind speeds increased by a factor of approximately two or more compared with the inflow data (25 m/s) when the wind passed between high-rise buildings. Generally, among the four wind directions, wind speeds were significantly enhanced when the north wind blew over both Marine City and LCT. The highest wind speed was observed at LCT when the west wind blew; however, the value was considerably local, with a significantly small contour area. Interestingly, the highest wind speed with a considerably local contour was observed near the tallest highrise building, supporting the hypothesis that wind speed increases rapidly downwind from the tallest building. As the height of the building increased, the downwind effect became stronger.

Badriana, M.R.; Lee, H.S.; Diastomo, H.; Avrionesti; Surya, M.Y.; Abdurrahman, U.; Suprijo, T., and Park, H., 2021. Multi-data ensemble estimation of wave energy potential in Indonesian seas. In: Lee, J.L.; Suh, K.-S.; Lee, B.; Shin, S., and Lee, J. (eds.), Crisis and Integrated Management for Coastal and Marine Safety. Journal of Coastal Research, Special Issue No. 114, pp. 271–275. Coconut Creek (Florida), ISSN 0749-0208.

Wave as blue energy is promising in Indonesia since it propagates directly from both the Pacific and Indian Oceans. Thus, preliminary study is necessary as a gate of initial development for wave energy conversion. Many wind-wave model results, reanalysis datasets, and satellite data are currently available and help researchers comprehend wave behavior and its energy produced. Multi-data ensemble estimation of wave energy with various methods, set-ups, and resolutions from those available resources would provide better accuracy, consistency, and insight for potential wave energy. This estimation is crucial because direct wave measurements are still not enough in Indonesian seas. The significant wave height and period are obtained from multi-data resources over seven years from 2011 to 2017. Each data is spatially interpolated onto a consistent grid of adequate data resolution and temporally daily averaged based on the spatial and temporal resolution of data used. Seasonal and monthly wave energy is considered since the monsoonal pattern plays a significant role in the Indonesian seas. For further possibility, wave energy potential is analyzed near coastal zones with less than 100 m depth. High wave energy potential is found promising off the coast of southern Java and western Sumatra.

Avrionesti; Hermawan, W.; Putri, M.R.; Diastomo, H.; Badriana, M.R.; Surya, M.Y.; Abdurrahman, U.; Suprijo, T., and Park, H., 2021. Anthropogenic carbon analysis in eastern Sumatra waters, Indonesia. In: Lee, J.L.; Suh, K.-S.; Lee, B.; Shin, S., and Lee, J. (eds.), Crisis and Integrated Management for Coastal and Marine Safety. Journal of Coastal Research, Special Issue No. 114, pp. 276–280. Coconut Creek (Florida), ISSN 0749-0208.

Human activities are increasing the production of released carbon dioxide into the air, land, or waters. The impact of those activities on the ocean was analyzed based on the calculation of anthropogenic carbon using inorganic carbon measurements. To enhance the understanding of carbon anthropogenic in another part of Indonesia, this research aims to get the spatial distribution of oceanic anthropogenic carbon at eastern Sumatra waters. The 2020 anthropogenic carbon is also calculated based on pH, salinity, and temperature trends and then compared with the revelle factor value to assess the carbon saturation of waters in eastern Sumatra. The concentration of anthropogenic carbon, in general, is inversely proportional to the revelle factor.

Yoon, J.; Kim, S.; Kim, I., and Song, D., 2021. Detection of wave parameters using CCTV images-based on deep learning algorithm. In: Lee, J.L.; Suh, K.-S.; Lee, B.; Shin, S., Lee, J. (eds.), Crisis and Integrated Management for Coastal and Marine Safety. Journal of Coastal Research, Special Issue No. 114, pp. 281–284. Coconut Creek (Florida), ISSN 0749-0208.

The closed-circuit television (CCTV) systems have been used for various applications in oceanic research fields. CCTV is an effective installation method for offshore monitoring that can conveniently and continuously observe the coastal region using the visible or infrared light in the electromagnetic spectrum. However, in the case of wave-observing CCTV images, there is a problem: it is difficult to extract the corresponding feature points between the video frames, which causes of inaccurate measurement of wave parameters. Recently, in the field of machine learning technology, deep learning-based video analysis that does not require the detection of feature points has been proposed. In this paper, we analyze wave-observing CCTV images with deep learning method in particular convolution neural network, and find the optimal method of observing waves through CCTV by three different datasets. For training, the CCTV data from the Samcheok Beach in the Republic of Korea were used. Wave observation data, which were used as input for machine learning, were collected by an acoustic wave and current profiler (AWAC). Moreover, to make up for insufficient observation data, the data to enhance the prediction model through deep learning were augmented. The results of this study confirm that the deep learning algorithm can be utilized to detect wave period and wave height. Consequently, continuous CCTV images can be combined with deep learning algorithm to clarify the complex characteristics of wave distribution and its temporal changes.

Suprijo, T.; Poerbo, P.R.; Park, H.; Kartadikaria, A.R., and Yosi, M., 2021. Potential ocean thermal energy conversion in Indonesian waters territory. In: Lee, J.L.; Suh, K.-S.; Lee, B.; Shin, S., and Lee, J. (eds.), Crisis and Integrated Management for Coastal and Marine Safety. Journal of Coastal Research, Special Issue No. 114, pp. 285–289. Coconut Creek (Florida), ISSN 0749-0208.

This study aims to estimate Ocean Thermal Energy Conversion (OTEC) resources in Indonesian Seas using six years (from 2011 to 2016) daily basis data resulted from numerical simulation of high-resolution (1/10°) ocean model, namely Japan Coastal Ocean Predictability Experiment (JCOPE), with covering a wide area (e.g. 9°N to 11°S and 95°E to 141°E). Estimation of thermal power resources was calculated based on temperature differences between surface layer and deep layer with water depth of 20 m and 1000 m from sea surface respectively. The net output power generated from OTEC and also OTEC operation is sensitive to the fluctuation of the temperature differences, therefore we also analyzed sea surface temperature variability in Indonesia Seas, in order to identify suitable waters area for OTEC operation. We found that Southern coast of Java, Nusa Tenggara and Banda waters are unsuitable for OTEC deployment area because of high temperature variability on the sea surface that can cause instability of power output from OTEC operation. The area, where is favorable for OTEC operation in Indonesia waters, is estimated about 3,773,552.7 square kilometers with total potential power rate that can be harvested around 451.7 GW per day. Surface temperature in Indonesia Seas is also influenced by global phenomena, namely the El Niño and the La Niña. When the El Niño occurs in 2015 to 2016, potential thermal power resources are decrease into 442 GW. Meanwhile, when the La Niña occurs in 2011 to 2012, the OTEC power resources are increase to 460 GW.

Jin, S.; Kim, D.; Lim, H.S., and Lee, H.J., 2021. Characteristics of water velocity variation according to the sluice and outflow direction of Dong-Sam seawater stream. In: Lee, J.L.; Suh, K.-S.; Lee, B.; Shin, S., and Lee, J. (eds.), Crisis and Integrated Management for Coastal and Marine Safety. Journal of Coastal Research, Special Issue No. 114, pp. 290–294. Coconut Creek (Florida), ISSN 0749-0208.

The Dong-Sam seawater stream flows within a seaside landfill providing waterfront areas for both people and marine lives. However, sewage and pollutants from nearby residential and industrial areas are being deposited due to slow flows. To improve water qualities by increasing flow velocities, this study conducted field observations using Aquadrifter and a Computational Fluid Dynamics (CFD) analysis in a total of six scenarios. The field observations show that the maximum velocities of 0.13 and 0.11 m/s occurred at the two ends of the stream, whereas flows were weakest in the central portion of the stream. In these circumstances, the scenario (Case III-b) for emplacing two sluice gates each at either stream end performs best to achieve the goal, increasing flow velocities. Case III-b scenario results in the increase of flow velocities in all the points in the model, even at the center area of the Dong-Sam seawater stream.

Chang, S.-Y.; Kim, J.-H.; Lee, H.-S., and Kim, I., 2021. Mechanism of rip current generation at Deoksan Beach, South Korea. In: Lee, J.L.; Suh, K.-S.; Lee, B.; Shin, S., and Lee, J. (eds.), Crisis and Integrated Management for Coastal and Marine Safety. Journal of Coastal Research, Special Issue No. 114, pp. 295–299. Coconut Creek (Florida), ISSN 0749-0208.

The coast serves as a buffer by reducing the energy of high waves and also serves as a leisure space for people. The east coast of Gangwon has become popular for its beach and for surfing in summer. Most beaches are sandy, and they have well-developed crescentic bars owing to exposure to high waves. The study site, Deoksan Beach, had an accident in which two college students drowned owing to rip currents at around 5:40 pm on July 13, 2019. The flow velocity and direction of the rip currents were identified using CCTV images at the time of the accident, and the causes of the currents were analyzed using data obtained from five water depths surveys conducted in 2017. At the time of the accident, the significant wave height was 0.6 m, the period was ∼7.5 s, and the wave direction was 54°. The survey results indicated that an environment suitable for rip current generation existed at this site. A numerical model experiment was conducted using the non-hydrostatic Surface Waves till Shore (SWASH) model to reproduce the occurrence of rip currents at the time of the accident, and the flow (surface: 0.38 m/s, average: 0.3 m/s) was found to be on the offshore side of the accident.

Lee, H.; Kim, J.; Chang, S., and Kim, I., 2021. Analysis of beach changes after construction of submerged breakwaters. In: Lee, J.L.; Suh, K.-S.; Lee, B.; Shin, S., and Lee, J. (eds.), Crisis and Integrated Management for Coastal and Marine Safety. Journal of Coastal Research, Special Issue No. 114, pp. 300–304. Coconut Creek (Florida), ISSN 0749-0208.

This study presents seasonal investigations of submerged breakwaters constructed from 2013 to 2014 as part of a government erosion prevention project in the region of Samcheok-si, South Korea. Parameters, including wave-induced currents, wave heights, beach profiles, and shoreline changes, were investigated to monitor and analyze sand transport trends in the study area. The construction of Gungchon Harbor in 2006 led to the transport of sand from southern Wonpyeong Beach to northern Gungchon Beach, which resulted in an average shoreline retreat of greater than 50 m. However, despite the subsequent construction of the submerged breakwaters, beach erosion continued to occur in adjacent areas. Specifically, a tombolo was generated behind the submerged breakwaters, which led to beach erosion. Rip currents were also typically generated near submerged breakwaters, which play a role in the offshore transportation of sand. Wonpyeong Beach experienced erosion following the construction of Gungchon Harbor, whereas Gungchon Beach exhibited accretion. Moreover, evidence of further erosion was observed near the breakwater construction area. Therefore, this study indicates that detailed monitoring during and after the construction of breakwaters is required to predict potential secondary erosion and understand the erosion mechanism for an optimal breakwater design.

Kim, H.D.; Aoki, S.; Oh, H.; Kim, K.H.; and Oh, J., 2021. Seabed sub-bottom sediment classification using artificial intelligence. In: Lee, J.L.; Suh, K.-S.; Lee, B.; Shin, S., and Lee, J. (eds.), Crisis and Integrated Management for Coastal and Marine Safety. Journal of Coastal Research, Special Issue No. 114, pp. 305–309. Coconut Creek (Florida), ISSN 0749-0208.

Understanding fluid mud density and depth can contribute directly to the development of strategies to reduce dredging costs and other problems in coastal waterways. Although echo sounders are most commonly employed to measure depth, each country has different ways to classify the sub-bottom echo character classification. This study aims to train and test the YOLOv3 artificial intelligence model to classify sub-bottom profiles along with the Darknet-53 framework. Two dataset packages with different amount of image data were used to compare the model performance. The mean average precision (mAP), loss, average intersection of union (IoU), and F1 scores were compared to interpret the results between dataset packages. Throughout the study, it was observed that when the number of images used in training was higher, the model training performances improved. The results of this study show that the YOLOv3 model was successfully trained and tested on the sub-bottom profile datasets, resulting in a high accuracy of classification detection.

Nakanishi, T.; Ohyama, T.; Hagiwara, H., and Sakuma, K., 2021. Impact of extreme typhoon events on the fluvial discharge of particulate radiocesium in Fukushima prefecture. In: Lee, J.L.; Suh, K.-S.; Lee, B.; Shin, S., and Lee, J. (eds.), Crisis and Integrated Management for Coastal and Marine Safety. Journal of Coastal Research, Special Issue No. 114, pp. 310–314. Coconut Creek (Florida), ISSN 0749-0208.

Two huge typhoons that occurred in October 2019, Hagibis and Bualoi, caused considerable flood damage in Fukushima Prefecture. There is concern about the radiocesium discharge to the coastal area related to such flood events from the river systems near the Fukushima nuclear power plant. In this study, we quantitatively evaluated the sediment and ¹³⁷Cs discharges from the Ukedo River catchment based on the field observations conducted over 6 years. In 2019, approximately 90% of the annual sediment and ¹³⁷Cs discharges occurred during the typhoon events (Hagibis and Bualoi). This sediment discharge was almost twice that related to the largest ever flood event since the Fukushima nuclear accident, which was caused by the typhoon Etau in September 2015. However, the ¹³⁷Cs discharge related to the Hagibis and Bualoi events was two-thirds of the Etau event; the particulate ¹³⁷Cs concentration in river water decreased during the observation period, showing an effective half-life of 2.2–3.9 years. Moreover, the ¹³⁷Cs discharge during the two typhoon events in 2019 accounted for only 0.1% of the ¹³⁷Cs deposition in the catchment, and the impact of radiocesium on the coastal area was extremely limited.

Misonou, T.; Tsuruta, T.; Shiribiki, T.; Nakanishi, T.; Nagao, S.; Ochiai, S., and Sanada, Y., 2021. Dynamics of radioactive cesium in coastal area linked with river discharge. In: Lee, J.L.; Suh, K.-S.; Lee, B.; Shin, S., and Lee, J. (eds.), Crisis and Integrated Management for Coastal and Marine Safety. Journal of Coastal Research, Special Issue No. 114, pp. 315–319. Coconut Creek (Florida), ISSN 0749-0208.

For understanding the dynamics of future radioactive cesium (Cs) and its distribution in the coastal area of Fukushima Prefecture, radioactive Cs supply from river discharge must be evaluated. Particulate radioactive Cs supplied by floods could significantly affect the coastal area. Therefore, the effect of particulate radioactive Cs supplied from the river was clarified by installing mooring systems (sediment traps and water quality meters) at four points (water depths of St.1: 10 m, St.2: 27 m, St.3: 30 m, and St.4: 60 m) in the coastal area of Fukushima Prefecture from October 22 to 28, 2019. During the observation period, a large typhoon (Bualoi) accompanied by torrential rain struck Fukushima Prefecture. The ¹³⁷Cs concentrations of the sinking particles collected by the sediment trap at the observation point installed in front of the river (St.1) were collected immediately after typhoon Bualoi (October 25) and were approximately three times higher than before the typhoon. However, the ¹³⁷Cs concentration of the sinking particles collected two days after the typhoon (October 27) was almost the same as before the typhoon. Local increases in ¹³⁷Cs were not observed at other stations. The stable carbon isotope ratio (δ¹³C) of the sinking particles during the typhoon was approximately –30 to –26‰ at the measurement points installed in front of the Ukedo, Ohta, and Kuma Rivers (St.1, St.2, and St.3). It was assumed that there was an influence of inflow from the river on St.1, St.2, and St.3 after precipitation. The impact of rivers on coastal areas during torrential rain is extremely limited.

Tsuruta, T.; Shiribiki, T.; Misonou, T.; Nakanishi, T.; Sanada Y., and Urabe, Y., 2021. Vertical profiles of radioactive Cs distributions and temporal changes in seabed sediments near river mouth in coastal area of Fukushima prefecture. In: Lee, J.L.; Suh, K.-S.; Lee, B.; Shin, S., and Lee, J. (eds.), Crisis and Integrated Management for Coastal and Marine Safety. Journal of Coastal Research, Special Issue No. 114, pp. 320–324. Coconut Creek (Florida), ISSN 0749-0208.

Understanding the features of radioactive Cs (¹³⁷Cs) in seabed sediments in coastal areas linked with rivers, which are major settlement areas for particulate ¹³⁷Cs, is a key issue in evaluating the supply of ¹³⁷Cs from river discharges. The vertical profile of ¹³⁷Cs distribution in seabed sediments is an important clue for elucidating the settlement process of particulate ¹³⁷Cs near river mouth. Therefore, we sampled seabed sediments using a long core sampler (vibrocoring; the maximum lengths of the core was approximately 100 cm) to clarify the entire vertical profile of the ¹³⁷Cs distribution and changes in seabed sediments near the river mouth in the coastal area of Fukushima Prefecture. From 2014 through 2019, the ¹³⁷Cs concentration along the entire vertical profile did not increase, and there was no remarkable migration of the ¹³⁷Cs toward the deeper layers of the seabed sediments. On the contrary, the amount of ¹³⁷Cs decreased by more than 70% throughout the entire depth, and the ¹³⁷Cs distributions in the depth direction become uniform. These results suggest that the supply of ¹³⁷Cs from the river discharge is not a major concern near the river mouth in the coastal area of Fukushima Prefecture. Resuspension of particle-bound ¹³⁷Cs and offshore transport are the main factors that reduce the ¹³⁷Cs concentration in the coastal seabed sediments.

Kim, J.-H.; Cho, G.-S.; Lee, J.-J.; Hong, S.-B.; Lee, E.-J.; Lee, B.-C., and Seo, B.-K., 2021. Development of scan survey adjust method for radioactively contaminated sediment in underwater conditions. In: Lee, J.L.; Suh, K.-S.; Lee, B.; Shin, S., and Lee, J. (eds.), Crisis and Integrated Management for Coastal and Marine Safety. Journal of Coastal Research, Special Issue No. 114, pp. 325–329. Coconut Creek (Florida), ISSN 0749-0208.

The nuclear power plants located near the coast and river to supply the cooling water. Therefore, unexpected radioactive materials leakage can contaminate the sediment on the coast, river, and lake. The conventional hotspot assessment methods are sampling and scan survey. The sampling method has limitations due to the sample representation, while the scan survey method is an easy way to assess hotspot distribution. However, the scan survey method can overestimate or underestimate the hotspot size depending on the radioactivity concentration, because this method determines the hotspot is exist when the measured count rate or dose rate exceeds the criteria level. In this study, the scan survey adjust method of sediment scan survey has developed. To this, the distribution of spatial effective dose rate was assessed by MCNP(Monte Carlo N-Particle) simulation. Also, the overestimation factor, which is the ratio of the actual hotspot size and estimated hotspot size was calculated. For the scan survey adjust method devised using the overestimation factor, maximum dose rate, and dose rate increase factor. Using this method, the scan survey experiment results were adjusted. As a result, ¹³⁷Cs survey result that was underestimated were adjusted 11.51∼73.05% overestimate. ⁶⁰Co survey result that was 2∼3 times overestimated was adjusted 2.02∼45.73% overestimate. Therefore, the scan survey adjusts method can prevent hotspot underestimation and reduced the relative error. This method can improve the accuracy of the hotspot scan survey in sediment.

Ji, Y.-Y.; Joung, S.; Min, B.I., and Suh, K.-S., 2021. Development and performance of underwater gamma-ray spectrometry for riverbed monitoring. In: Lee, J.L.; Suh, K.-S.; Lee, B.; Shin, S., and Lee, J. (eds.), Crisis and Integrated Management for Coastal and Marine Safety. Journal of Coastal Research, Special Issue No. 114, pp. 330–334. Coconut Creek (Florida), ISSN 0749-0208.

The atmospheric release and fallouts of radionuclides have produced the radioactive contamination over wide area in the accident at the Fukushima Daiichi nuclear power plant (FDNPP). They still affect the environment around the Fukushima Prefecture, such as resident area, fields, mountainous area, river and stream, and reservoir. In JAEA (Japan Atomic Energy Agency), diverse monitoring platforms have been developing and successfully applying to the assessment of environmental radiation and deposited nuclides. Especially, there are about 3,700 irrigation reservoirs around the Fukushima Prefecture, which can be effected from direct fallouts in reservoirs as well as dispersions of the contamination in the other sites, depending on weather conditions. Underwater survey system is an important tool to assess the radioactive contamination in the river, stream and reservoir, including the bottom sediments. In this study, underwater gamma-ray spectrometry, named as MARK-U1, was developed to rapidly estimate the underwater radioactivity for the emergency preparedness, according to the lesson learned from the nuclear accident of FDNPP. A 3”φx3” NaI(Tl) detector is equipped in this underwater system and the lateral shielding around a detector was also designed using lead with a thickness of 1 cm to confine the field of view. Finally, its performance test was conducted by evaluating the natural radioactivity of ²¹⁴Bi, ²⁰⁸Tl, and ⁴⁰K in the riverbed of reservoir.

Yoon, I.J., 2021. Assessment of performance related to Sustainable Development Goal 14 (SDG 14) for countries around the Korean peninsula. In: Lee, J.L.; Suh, K.-S.; Lee, B.; Shin, S., and Lee, J. (eds.), Crisis and Integrated Management for Coastal and Marine Safety. Journal of Coastal Research, Special Issue No. 114, pp. 335–339. Coconut Creek (Florida), ISSN 0749-0208.

This study reviews the Sustainable Development Goal 14 (SDG 14) performances of coastal nations around the Korean Peninsula. Based on the four indicators provided by the Sustainable Development Solutions Network (SDSN), this study analyzes the current status and trends of SDG 14 performances of the Republic of Korea (ROK), Democratic People's Republic of Korea (DPRK), China, Japan, and Russia. The analysis is conducted using dimensional and developmental approaches. The Yellow Sea, surrounded by ROK, DPRK, and China, is facing challenges with regard to water pollution, while the East Sea surrounded by ROK, DPRK, Japan, and Russia is facing overexploitation of fish and water pollution. Development-wise, countries in this group that belong to the Organization for Economic Co-operation and Development (OECD), namely ROK and Japan, tend to have higher values for positive indicators and lower values for negative indicators. DPRK shows no achievement with respect to any indicator, while the others have progressed with respect to at least one indicator, which indicates the necessity for more regional cooperation. The significance of this study is that assessment of SDG 14 performances of coastal nations around the Korean peninsula was carried out for the first time at both the individual and regional levels, and the related characteristics of each nation and necessity of collective efforts were drawn out.

Jin, H.K. and Yoon, I.J., 2021. A review of the ocean economy of North Korea: Relationship between economic status and fisheries policy. In: Lee, J.L.; Suh, K.-S.; Lee, B.; Shin, S., and Lee, J. (eds.), Crisis and Integrated Management for Coastal and Marine Safety. Journal of Coastal Research, Special Issue No. 114, pp. 340–344. Coconut Creek (Florida), ISSN 0749-0208.

This study aims to review the ocean economy of North Korea, more specifically, the relationship between the North Korean economy and its fisheries policy, as fisheries hold a dominant position in the ocean economy. To achieve the purpose of this study, the North Korean economy and fisheries sector have been analyzed regarding policy and performance since 1953. Most materials rely on literature reviews generated by North Korea or on statistical figures estimated by South Korea. The main hypothesis of this study is that the North tends to emphasize fishing when its economic status is relatively fine, while it moves its policy focus from fishing to aquaculture when the economy goes down. Based on the analysis of the history of the North Korean economy and fisheries policy, this hypothesis was tested and examined. The DPRK government emphasized and promoted coastal and offshore fisheries in the 1970s but turned to mariculture in the 1980s when economic recession worsened. Again, the DPRK focused on inland aquaculture during the 1990s when the economy was at its lowest. In the wake of economic recovery, the DPRK fostered the fishing sector in the early and mid-2010s; however, the country has turned back to aquaculture since 2017 when the UN sanctions were tightened. As there are not many studies that address fisheries in North Korea, this study highlights their importance and implications on its economy.

Kim, J.-S. and Jang, S.-H., 2021. Proposal for the expansion of research on the South Korean Marina Development Project. In: Lee, J.L.; Suh, K.-S.; Lee, B.; Shin, S., and Lee, J. (eds.), Crisis and Integrated Management for Coastal and Marine Safety. Journal of Coastal Research, Special Issue No. 114, pp. 345–349. Coconut Creek (Florida), ISSN 0749-0208.

The South Korean Marina Development Project includes a long-term plan to construct an industrial cluster and a marina business model by developing marinas nationwide since 2010. This plan aims to develop coastal/fishing regions across the country into leisure hotspots. Building on active support from the government, this led to the establishment of the Second Marina Basic Plan in 2020, making this the largest marine leisure project in the country to date. Unfortunately, many marinas across the country face severe difficulties owing to various causes. In this study, we aimed to suggest new directions for research on the Marina Development Project as part of a series of academic efforts to resolve problems with the project. To this end, we conducted a literature review to explore (1) the current project and the directions of previous research by inspecting “the current state of the Marina Development Project and related research trends” and (2) “the expansion of research on the Marina Development Project.” More specifically, we claim that there is a need for “critical research examining the nature of the problems that have caused failure to date” and for a “cultural approach to participants.” Finally, we also emphasize the need for “community governance research” as a practical and long-term solution. This expansion of research can guide recovery from the various difficulties faced by the current Korean Marina Development Project.

Baek, E.Y., 2021. Oyster shell recycling and marine ecosystems: A comparative analysis in the Republic of Korea and Japan. In: Lee, J.L.; Suh, K.-S.; Lee, B.; Shin, S., and Lee, J. (eds.), Crisis and Integrated Management for Coastal and Marine Safety. Journal of Coastal Research, Special Issue No. 114, pp. 350–354. Coconut Creek (Florida), ISSN 0749-0208.

Oyster shell management is important for a sustainable oyster industry, and if oyster shells are utilized as resources, they will also contribute significantly to the creation of added value. The Republic of Korea and Japan are top producers of oyster shells but treat them very differently as resources. First, all oyster shell management laws in Korea are controlled by the “Waste Control Act,” while in Japan, if waste is recycled into a useful resource, although it is still subject to the “Waste Control Act,” such waste can be treated differently. Second, the cost of recycling oyster shells is different in both countries. In Korea, the cost is the same nationwide, but in Japan, there is no subsidy provided to oyster farmers, and the regional processing costs are different. Finally, industrialization accounts for a majority of fertilizers/animal feed in the Republic of Korea, but oyster shells have been utilized for these in Japan. Thus, the present study aimed to draw policy implications for effective reuse of oyster shells by comparing the related laws, costs, and wasting and recycling technologies between the Republic of Korea and Japan.

Kim, C.W.; Park, J.Y.; Choi, H.-J., and Nam, J., 2021. Interpreting the relevance between marine spatial planning and ecosystem services in Busan, South Korea. In: Lee, J.L.; Suh, K.-S.; Lee, B.; Shin, S., and Lee, J. (eds.), Crisis and Integrated Management for Coastal and Marine Safety. Journal of Coastal Research, Special Issue No. 114, pp. 355–359. Coconut Creek (Florida), ISSN 0749-0208.

Marine spatial planning (MSP) and marine ecosystem services (MES) have been increasingly gaining attention among global, national, and local societies. Among challenging issues in MSP practices is the incorporation of MES into MSP process in terms of advancement of marine management system. In this regard, we explored and interpreted the relevance between the zoning scheme under MSP and marine ecosystem service distribution in Busan sea area and EEZ. The total area under MSP enforcement is 5526.44 km², and the total value of ecosystem services accounted for 272.73 million US dollars. The averaged MES value per grid (0.93 × 0.93 km) is 264.74 thousand US dollars, with large difference among zones. The fisheries protected zone has the largest area, but its MES value accounted for only 28% of the total. Area and MES value of marine tourism zone were 2.30% and 13.98%, respectively. MES value was relatively high in the inshore and low in the offshore. The high cultural service value in this area reflects socioeconomic features of the Busan metropolitan city. In terms of the relation between area and MES value of each zone, fisheries protected zone and provisioning service, and environment-ecosystem management zone and regulating services were well matched. Meaningful relation in the tourism zone between area and the value was not identified. This study is expected to contribute to exploring and interpreting the relevance between MSP and MES, and applying MES to the planning process and marine management.

Choi, H.-J.; Cho, S.-J.; Hwang, T.; Nam, J., and Hwang C.S., 2021. Cumulative impact assessment for marine spatial planning: A case study of the Gyeonggi Bay in South Korea. In: Lee, J.L.; Suh, K.-S.; Lee, B.; Shin, S., and Lee, J. (eds.), Crisis and Integrated Management for Coastal and Marine Safety. Journal of Coastal Research, Special Issue No. 114, pp. 360–364. Coconut Creek (Florida), ISSN 0749-0208.

Cumulative impact assessment (CIA) techniques for marine spatial planning (MSP) exist in Europe and North America. Effective MSP requires a process for evaluating the effects of human activities on marine ecosystems, that is, a CIA. In Korea, MSP has progressively been developed for waters since the enactment of an MSP law (Act on Marine Spatial Planning and Management) in 2019. This study aims to perform the first CIA for Korea, evaluate its limitations, and assess alternatives for an operational MSP. This study involves an extensive review of the literature, followed by an assessment of the cumulative impact of human activities on the marine ecosystem in Gyeonggi Bay, Korea. Information on the marine ecosystems and influencing activities was collected, and the concept of the activity–pressure–ecosystem relationships adopted. The results reveal high cumulative impact scores along the coast, where human activities are concentrated, with fishing activities accounting for the highest proportion (i.e., 60.3% for gillnet, trap, and stow-net fishing) of the total cumulative impact among the marine activities. The cumulative impact is confirmed to vary by activity depending on whether the weight of the marine ecosystem is applied. This study provides an overview for quantifying the cumulative impacts of marine activities within a spatial context. It also highlights the importance of adequately considering the collection and processing of data before CIA. In addition, the activity–pressure–ecosystem linkage concept must consider the conditions of the study area to improve the accuracy and reliability of CIA. Further, the analysis and mapping techniques for CIA require improvement. This study can be used as a guideline for developing and utilizing the CIA tool in countries and regions planning to adopt MSP.

Oh, C.; Nam-Jo, S.K., and Kim, K.-B., 2021. Convergence and integration of the MICE and maritime industries: An analysis of the MICE industry of Busan. In: Lee, J.L.; Suh, K.-S.; Lee, B.; Shin, S., and Lee, J. (eds.), Crisis and Integrated Management for Coastal and Marine Safety. Journal of Coastal Research, Special Issue No. 114, pp. 365–369. Coconut Creek (Florida), ISSN 0749-0208.

This study examines whether Busan's exemplary MICE (Meeting, Incentive tour, Convention, Exhibition) environment can accelerate the development of various core industries, especially the maritime industry, when convergence and integration occur with MICE. Prior research suggests that the introduction of new products, services and technologies at conventions has a direct effect on the development of related industries by increasing awareness and attracting new participants. Busan hosts exhibitions and conventions that attract professionals from the maritime industry. The participants of marine-related MICE events in Busan were surveyed to examine the current status and the future of the maritime industry and the MICE industry. A focus group interview with 11 MICE industry professionals was first conducted to examine and verify the attributes of the MICE destination. Secondly, the Analysis Hierarchy Process (AHP) was used with 41 professionals to test the importance of the attributes in the survey items. Finally, a survey of 217 people who attended marine-related exhibitions in BEXCO was conducted to examine the strengths and weaknesses of Busan as a MICE destination for the maritime industry. The findings revealed that the city's key strengths are site environment with attractive climate and safe environment, transportation infrastructure, and level of cooperation within the MICE industry. However, the level of cooperation between the MICE industry and maritime industry needs improvement.

Lee, J.-H. and Kim, C.-R., 2021. Regulation-oriented beach utilization plan. In: Lee, J.L.; Suh, K.-S.; Lee, B.; Shin, S., Lee, J. (eds.), Crisis and Integrated Management for Coastal and Marine Safety. Journal of Coastal Research, Special Issue No. 114, pp. 370–374. Coconut Creek (Florida), ISSN 0749-0208.

This study analyzed issues, which were perceived as regulations by visitors to beaches, according to the Act on Management and Use of Beaches in South Korea from various aspects and proposed improvement measures. Interdisciplinary and comparative analyses were conducted as well as in-depth interviews with a group of experts. Based on the results, the following conclusions were derived. First, visitors to beaches perceived issues regarding management and operation of beaches (e.g., an excessive range of water leisure zones established, conflicts over unfairness related to designation of assignees for management and operation of beaches, and an excessive level of authority empowered to assignees) as regulations. Second, they also perceived issues on safety and environment management (e.g., prohibited or limited use of beaches for safety) as regulations.

Nam-Jo, S.K.; Kim, K.-B., and Oh, C., 2021. Beaches for everyone? Marine tourism for mobility impaired visitors in Busan, Korea. In: Lee, J.L.; Griffiths, T.; Lotan, A.; Suh, K-S, and Lee, J. (eds.), Crisis and Integrated Management for Coastal and Marine Safety. Journal of Coastal Research, Special Issue No. 114, pp. 375-379. Coconut Creek (Florida), ISSN 0749-0208.

As an international tourism destination, the needs of all travelers must be accommodated, especially those of mobility-impaired visitors. However, the number of tour agencies that accommodate disabled tourists is woefully inadequate, with only seven operating in Korea. As senior citizens constitute a growing proportion of the world population, the number of wheelchair users will surely increase as well. Busan also faces the current issue of an ageing population, with highest proportion of elderly residents in the nation. This study is the first to examine the needs and preferences for marine tourism among the mobility-impaired population in Korea with beach wheelchair experience. The results of the survey conducted among 110 beach wheelchair users revealed a significantly high level of satisfaction with the tour and expressed their intent to return. These results highlight the need for the development of tourism policies and the tourism environment for physically impaired travelers. Furthermore, tourism budgets should be used to better accommodate mobility-impaired travelers, and to improve the city's standard as an international tourism destination.

Um, D.-B., 2021. Configuring legitimate blue carbon rights for coastal fishing villages based on forestry carbon MRV. In: Lee, J.L.; Suh, K.-S.; Lee, B.; Shin, S., and Lee, J. (eds.), Crisis and Integrated Management for Coastal and Marine Safety. Journal of Coastal Research, Special Issue No. 114, pp. 380–384. Coconut Creek (Florida), ISSN 0749-0208.

Blue carbon refers to carbon dioxide removed from the atmosphere by the coastal ecosystems. The price of carbon credit in South Korea initiated in January 2015 has soared more than five times as of 2020. Even if domestic companies participating in emission trading want to invest in offset trading of blue carbon abundant in the coastal area of South Korea, there is no fundamental governance to trade blue carbon. This article suggests ways to configure legitimate carbon rights through Measurement, Reporting and Verification (MRV) by defining the sub-category of blue carbon compared to forest carbon. This MRV contract between wetland villages and local companies could be implemented by guaranteeing carbon rights to wetland village communities from land ownership. Although South Korea has been selected as a case study for this paper, this discussion is relevant to other countries that face blue carbon incentives to attract local companies' emission reduction demand.

Kang, H.-M., 2021. Development of safety practice competency on the beach: Focusing on life-respect and participation in survival swimming programs among elementary school students. In: Lee, J.L.; Suh, K.-S.; Lee, B.; Shin, S., and Lee, J. (eds.), Crisis and Integrated Management for Coastal and Marine Safety. Journal of Coastal Research, Special Issue No. 114, pp. 385–389. Coconut Creek (Florida), ISSN 0749-0208.

The purpose of this study is to develop safety practice competency on the beach through a survival swimming program designed for elementary school students. There are numerous factors that affect the various accidents that may occur on the beach. Therefore, it is necessary to identify, control, and respond to these accidents by analyzing multiple factors. In order to achieve this purpose, 248 elementary students were selected from registered schools in the Kangwon-do area. In this paper, we focus on the analysis factors of safety practice competency, life-respect, and participation in a survival swimming program assessment model. This study applies structural equation model analysis for effect between each factor. Additionally, this study conducts experiments to develop a safety practice competency protocol by calculating and affecting the factors. We conclude that various approaches to the survival swimming program are needed from the perspective of interdisciplinary fusion research. We establish a framework to investigate the competency of safety practices in different situations.

Kim, K.B. and Yun, H.S., 2021. High-resolution bathymetry in shallow waters off the southern coast of Korea from satellite altimetry and remote sensed imagery. In: Lee, J.L.; Suh, K.-S.; Lee, B.; Shin, S.; and Lee, J. (eds.), Crisis and Integrated Management for Coastal and Marine Safety. Journal of Coastal Research, Special Issue No. 114, pp. 390–394. Coconut Creek (Florida), ISSN 0749-0208.

Bathymetry in shallow waters off coastal areas has been measured using conventional methods such as with single-beam and multi-beam echo-sounders installed on the ship. However, shipborne depth data are spatially limited and unevenly distributed over shallow waters off coastal areas. In this study, various methods that use satellite altimetry-derived gravity anomalies and high-resolution remote sensed imagery were explored for the recovery of high-resolution bathymetry data over shallow waters off Gwangyang Bay between Yeosu Peninsula and Namhae Island on the South Sea of Korea. Estimated high-resolution bathymetry data from satellite altimetry-derived gravity anomalies and remote sensed imagery were compared with shipborne depth measurements to validate their accuracy in shallow waters. This study concluded that bathymetry data estimated with the gravity-geologic method (GGM) in shallow waters are better than those predicted by Sentinel-2 imagery.

Lee, J.-C.; Koh, Y.-C., and Lee, D.-H., 2021. Strategic improvement plan to increase the usability of coastal base maps throughout Korea. In: Lee, J.L.; Suh, K.-S.; Lee, B.; Shin, S., and Lee, J. (eds.), Crisis and Integrated Management for Coastal and Marine Safety. Journal of Coastal Research, Special Issue No. 114, pp. 395–399. Coconut Creek (Florida), ISSN 0749–0208.

The National Geographic Information Institute constructs and supplies coastal base maps containing spatial and geographic information. The main purpose is securing basic data for designing and developing coastal waters. However, there has been no continuous construction of information for all coastal waters in Korea; therefore, detailed and precise coastal water information for each coastal situation cannot be provided. This study introduces a continuous and unified coastal base map for all coastal waters in Korea. The introduced map can be employed to provide coastal water information with high utility, and widely used not only in coastal construction projects but also in various industries related to the spatial development of coastal waters.

Han, D. and Lee, C., 2021. Mapping of coastal zones using Unmanned Aerial Vehicle (UAV) video sequences. In: Lee, J.L.; Suh, K.-S.; Lee, B.; Shin, S., and Lee, J. (eds.), Crisis and Integrated Management for Coastal and Marine Safety. Journal of Coastal Research, Special Issue No. 114, pp. 400–404. Coconut Creek (Florida), ISSN 0749-0208.

Collecting accurate and detailed geological and dynamic information on coastal processes is required for coastal erosion and coastal facility monitoring. Over the past decades, video monitoring systems have demonstrated to be a cost-effective method. Nevertheless, extracting information with consistent accuracy of the coast with video processing is difficult due to the limitation of the geometric field of view from the top of the tower. In this work we apply a framework for geographic mapping in coastal videos using Unmanned Aerial Vehicles (UAV). Specifically, we address the coast modeling using video frames. The system is designed to be deployed utilizing inexpensive, off-the-shelf hardware, in such a way that the results can be easily replicated by other applications. Therefore, it was possible to obtain geometrical accuracy similar to using photo to video frames.

Lee, J.; Kwon, J.H.; Lee, Y., and Lee, H., 2021. Development of the Korean National Geoid Model (KNGeoid18) and applications for the height determination of coastal land points. In: Lee, J.L.; Suh, K.-S.; Lee, B.; Shin, S., and Lee, J. (eds.), Crisis and Integrated Management for Coastal and Marine Safety. Journal of Coastal Research, Special Issue No. 114, pp. 405–409. Coconut Creek (Florida), ISSN 0749-0208.

Since 2008, new land gravity data showing a homogeneous distribution and high precision have been obtained in Korea. In addition, a new version of the global geopotential models which were developed based on observations by the Gravity Field and Steady-State Ocean Circulation Explorer (GOCE) satellite are available. Thus, a gravimetric geoid was newly developed by the “Remove-Restore” technique using the experimental gravity field model 2016 (XGM2016) and more than 12,000 points of land gravity data. In addition, airborne, shipborne, and Danish Technical University 2010 (DTU10) altimeter gravity data, as well as a terrain model, were applied for geoid modeling. As a final product of the study, the hybrid geoid, Korean National Geoid model 2018 (KNGeoid18), was modeled by fitting the gravimetric geoid to a total of 2,791 points of global navigation satellite system (GNSS)/leveling data located over the entire Korean peninsula. The degree of fit of KNGeoid18 was calculated to be approximately 2.3 cm. One of the necessities of a local geoid model is to efficiently determine the orthometric height in terms of time and cost. Thus, GNSS surveying was conducted at 19 points and GNSS-derived orthometric heights were computed. Among the 19 points, the precision of the official orthometric heights at 12 points located in mountainous areas is known to be larger than 10 cm; hence, the GNSS-derived orthometric heights were calculated using Trimble business center (TBC), Leica geo-office (LGO), and Giodis, and compared with each other. As a result, it was found that the difference in heights at 12 points did not exceed 5 cm. The other 9 points, located in coastal areas, had a difference smaller than 3 cm compared to the official orthometric height. It is expected that orthometric heights with a target precision of 3–5 cm would be determined by GNSS surveying and the local geoid model, but an improvement of the geoid model in mountainous areas is still necessary.

Park, J.K. and Jung, K.Y., 2021. Utilization of an Unmanned Aerial Vehicle and echo-sounder for shoreline surveying. In: Lee, J.L.; Suh, K.-S.; Lee, B.; Shin, S., and Lee, J. (eds.), Crisis and Integrated Management for Coastal and Marine Safety. Journal of Coastal Research, Special Issue No. 114, pp. 410–414. Coconut Creek (Florida), ISSN 0749-0208.

The shoreline is a baseline that defines the shape of the national territory or defines the borders of the seas between countries, and it is important geospatial information to be managed by the nation for international and legal responses. In addition, importance is increasing day by day as a guideline for various laws that determine the spatial scope of the land, coast, and ocean, and closely related to people's lives. In this study, geospatial information was constructed using UAV (Unmanned Aerial Vehicle) and echo-sounder to investigate shoreline changes. UAV was used to survey the coastal area during ebb tide, and echo-sounder was used to measure areas where UAV is not applicable and to integrate with UAV data. The data surveyed by UAV was processed to create a DSM(Digital Surface Model) and ortho image. And echo-sounder was used for depth measurement during high tide, and was used to construct geospatial information for coastal areas by integrating with UAV data. As a result of the study, geospatial information about the study area could be constructed. The UAV results showed X, Y, and H deviations within 5.5 cm compared to the check point survey results using GNSS and it suggesting the possibility of using the results. The shoreline variation survey should be conducted from the existing “line concept” survey to the “plane concept” survey. In this regard, the result of integrating UAV and echo-sounder will be a way to effectively build plane data through data processing. Shoreline change survey using UAV and echo-sounder can be used to establish and manage standardized shoreline data and establish predictable mid- and long-term national maritime policies through continuous shoreline survey. In addition, it will help effective business execution as data for the execution of major marine policies such as coastal management and marine safety.

Kim, M. and Bae, T.-S., 2021. High-accuracy GNSS positioning of ocean vessels for sea wave monitoring. In: Lee, J.L.; Suh, K.-S.; Lee, B.; Shin, S., and Lee, J. (eds.), Crisis and Integrated Management for Coastal and Marine Safety. Journal of Coastal Research, Special Issue No. 114, pp. 415–419. Coconut Creek (Florida), ISSN 0749-0208.

This study aims to develop a high-precision strategy for the positioning of marine vessels to monitor sea waves. Thus, the total electron content (TEC) in the ionosphere will be accurately corrected in the positioning process. We analyzed various aspects of ionospheric delay using the Global Ionosphere Map (GIM). The results indicated that the ionosphere was affected by the frequencies and long-term changes of the TEC. It is critical to synchronize the correction information and GNSS observation data on ocean vessels. We developed a methodology for the time synchronization of the GIM, specifically for the ocean, on which only a small number of continuously operating reference station (CORS) networks are available. The generated ionosphere model was compared to the GIM with a maximum of 1.6 TEC, which should be verified for a longer period of time.

Choung, Y.-J. and Jung, D. 2021. Comparison of machine and deep learning methods for mapping sea farms using high-resolution satellite image. In: Lee, J.L.; Suh, K.-S.; Lee, B.; Shin, S., and Lee, J. (eds.), Crisis and Integrated Management for Coastal and Marine Safety. Journal of Coastal Research, Special Issue No. 114, pp. 420–423. Coconut Creek (Florida), ISSN 0749–0208.

Previous research had shown that the supervised machine learning approach performed better than unsupervised machine learning for mapping sea farms using a high-resolution satellite image. The present work compares a support vector machine (SVM), which represents the supervised machine learning approach, and a deep neural network (DNN), which represents the deep learning approach, for mapping sea farms using KOMPSAT-3 satellite images acquired in the South Sea of South Korea. First, coastal maps were generated from the image source given by SVM and DNN. Next, the above-water and underwater farms were detected separately from both the maps based on the minimum and maximum thresholds. Finally, the detection accuracy of both the above-water and underwater farms from both coastal maps was assessed. Statistical results showed that deep learning (DNN) provided better performance than machine learning (SVM) for detecting above-water farms from the given high-resolution satellite image, while both DNN and SVM yielded the same performance for underwater farms. However, a few errors occurred in the detection because of the limitations of the pixel-based classification approaches. In future research, the deep learning algorithm combined with object-based classification, such as the convolutional neural network, can be used to detect sea farms from the given high-resolution image more accurately.

Oh, H.Y.; Jeong, M.-H.; Jeon, S.B.; Lee, T.Y.; Kim, G., and Youm, M., 2021. Sea water quality estimation using machine learning algorithms. In: Lee, J.L.; Suh, K.-S.; Lee, B.; Shin, S.; and Lee, J. (eds.), Crisis and Integrated Management for Coastal and Marine Safety. Journal of Coastal Research, Special Issue No. 114, pp. 424–428. Coconut Creek (Florida), ISSN 0749-0208.

The water quality index (WQI) determines the quality of drinking water and seawater. Currently, coastal and seawater quality is monitored and managed by classifying it into five grades based on the WQI value in the Republic of Korea. The Korea Marine Environment Management Corporation (KOEM) utilizes automatic environmental sensor networks to monitor the coastal environment. However, these sensor data do not include the essential variables for determining the water quality level. The KOEM manually evaluates the WQI four days per year. This study estimates the water quality level using machine-learning algorithms based on the measurements of the automatic environmental sensor network data. The experiments show that random forest and support vector machine algorithms perform better than other algorithms. The results of this study can be applied to monitor and predict water quality in real time.

Huynh, V.M.; Hong, S.; Kwon, Y.; Tran, V.T.; Huynh, V.T.M., and Kwon, S., 2021. An optimal rain-gauge network using a GIS-based approach with spatial interpolation techniques for the Mekong River Basin. In: Lee, J.L.; Suh, K.-S.; Lee, B.; Shin, S., and Lee, J. (eds.), Crisis and Integrated Management for Coastal and Marine Safety. Journal of Coastal Research, Special Issue No. 114, pp. 429–433. Coconut Creek (Florida), ISSN 0749-0208.

Rainfall is one of the crucial types of data for hydrometeorological studies. In the context of climate change, which has become increasingly complex, hydrometeorological forecasting data are urgently necessary for further climatic simulation modeling. However, it is always a big challenge to achieve accurate rainfall data for such a minimum observation cost. Hence, an optimization design for the rain-gauge network in southern Vietnam was developed in this study, with a focus on the quantity and spatial distribution of rain gauges. The well-known geostatistics method combined with a spatial interpolation algorithm was applied using input rainfall data over the past 40 years. The selection of the appropriate spatial interpolation method affected the accuracy of the optimization process. The results of the interpolation analysis indicated the spatial variability of the rainfall patterns throughout the study area according to the seasons, as well as the geographic distribution of the rainfall, especially in the coastal area. The primary criterion for reducing the estimated data' uncertainty is improving the network density by installing additional rain-gauge stations. In this research, after the optimal number of stations was determined, a geographic information system-based approach and a multilayer overlaying technique were used to obtain the optimal rain gauges spatial distribution map. For future research, the proposed method is capable to apply in other related works to obtain more accurate rainfall estimation data.

Lee, H.-S. and Oh, J.-H., 2021. Correcting Digital Elevation Models (DEM) from Unmanned Aerial Vehicles (UAV): A new method using polynomial model matching techniques. In: Lee, J. L.; Suh, K.-S.; Lee, B.; Shin, S., and Lee, J. (eds.), Crisis and Integrated Management for Coastal and Marine Safety. Journal of Coastal Research, Special Issue No. 114, pp. 434–438. Coconut Creek (Florida), ISSN 0749-0208.

Korean coastal regions have large mudflats that shelter endangered migratory birds and many prosperous ecosystems inhabited by various species living in clusters. To recognize the topographical and environmental characteristics of the coastal regions and to systematically manage them, it is essential to obtain topographical maps of the geographical and environmental characteristics. In particular, the height information of the mudflats is critically important in monitoring changes caused by either natural or artificial influences. Recently, Unmanned Aerial Vehicles (UAV) are shown to be potential candidates in preparing accurate Digital Elevation Models (DEMs) of a terrain. But a major problem in using UAVs is that it is almost impossible to conduct a field survey of Ground Control Points (GCPs). This is because the mudflat areas are not easy to approach places where the proportion of silt and clay content is very high. Without GCPs, the DEM produced from the UAV images and photogrammetric software tend to show a nonlinear distortion due to the aerial triangulation errors. Therefore, we propose a least-square height-difference DEM matching with a polynomial model. This method uses a reference DEM obtained from aerial images to compensate for the location error and the aforementioned nonlinear distortion. Experimental results showed that this significant DEM error modeling was possible with curvilinear translation and constant rotation parameters along the diagonal direction of the test DEM that significantly reduce the location errors and almost eliminate the nonlinear distortion of the UAV-derived DEM.

Kim, G.; Jeong, M.-H.; Jeon, S.-B.; Lee, T.-Y.; Oh, H.-Y., and Park, C.-S., 2021. Determination of optimal locations for offshore wind farms using the analytical hierarchy process. In: Lee, J.L.; Suh, K.-S.; Lee, B.; Shin, S., and Lee, J. (eds.), Crisis and Integrated Management for Coastal and Marine Safety. Journal of Coastal Research, Special Issue No. 114, pp. 439–443. Coconut Creek (Florida), ISSN 0749-0208.

The ocean is one of the largest renewable energy sources. Offshore wind energy has attracted considerable attention owing to the increasing adoption of renewable energy technologies; therefore, it is vital to select the most appropriate sites for offshore wind farms. This study aims to select the optimal sites for offshore wind farms based on the analytical hierarchy process(AHP). This study considered 11 criteria: wind speed, water depth, distance from the shore, ship route density, military operations areas, marine ecosystem protection areas, marine biodiversity protection areas, special protected islands, protected areas for wildlife, cultural heritage sites, and national parks. The feasibility of potential sites for offshore wind farms was evaluated across the Korean Peninsula. The southern coast between Goheung and Yeosu is the most optimal area for installing offshore wind farms, followed by the west coast of Taean.

Abdurrahman, U.; Diastomo, H.; Avrionesti; Surya, M.Y.; Badriana, M.R.; Suprijo, T., and Park, H., 2021. Comprehensive analysis of coastal dynamics in Cirebon Coastal Area (CCA), Indonesia. In: Lee, J.L.; Suh, K.-S.; Lee, B.; Shin, S., and Lee, J. (eds.), Crisis and Integrated Management for Coastal and Marine Safety. Journal of Coastal Research, Special Issue No. 114, pp. 444–448. Coconut Creek (Florida), ISSN 0749-0208.

Cirebon Coastal Area (CCA), which covers Cirebon City and Cirebon District, is an area located on the north coast of Java Island, Indonesia. The area was among the coastal areas with a high-density population in Indonesia. Human activities in this area, which are dominated by industries, fisheries, and agriculture, strongly influenced the coastal environmental conditions. One of the effective and accurate ways to monitor the coastal environmental conditions is to utilize remote sensing technology which has grown significantly in recent years. Although various studies have been conducted, different results were shown and indicated that the coastal dynamics in CCA were not fully understood yet. This research provides comprehensive analysis with the aim to comprehend the complete pattern of coastal dynamics in CCA. Analysis of coastal dynamics has been carried out by using a combination of Landsat and Google Earth data. This robust combination allowed to cover a longtime span (1996-2020), periodic, and high-resolution data analysis Results indicated that along the CCA shoreline the accretion was dominated rather than the erosion. While on the eastern area showed more dynamic changes rather than the western area, especially at Losari, Pangenan, and Lemahwungkuk sub-districts.

Lee, C.K.; Yun, K.; He, G., and Park, B.W., 2021. Estimation of submerged coast by existing survey data and topographic survey. In: Lee, J.L.; Suh, K.-S.; Lee, B.; Shin, S., and Lee, J. (eds.), Crisis and Integrated Management for Coastal and Marine Safety. Journal of Coastal Research, Special Issue No. 114, pp. 449–453. Coconut Creek (Florida), ISSN 0749-0208.

The purpose of this study is to investigate whether registered land located on a coast is submerged during high tide. The most important data when judging whether the registered coastal land is submerged are cadastral maps and topographic maps. In Korea, all land parcels have been registered in the land ledger and cadastral map in the 1910s. A land ledger is a document that contains the address, area, title, grade, and owner of the parcel, whereas a cadastral map is a graphical representation that contains the location and boundary of a parcel. Even if the boundary of the parcel changes at the site, the boundary of the cadastral map remains unchanged before the land register is modified officially by the request of the owner. For submerged land, two cases exist. Case 1 is after the land is submerged and left without restoration. Case 2 is after the land has been restored following its submersion. In case 1, the coastline of a submerged land can be surveyed by surveying in situ. However, in case 2, the coastline cannot be surveyed at the time it is submerged. In this study, a coastline is extracted using aerial images after it was submerged. When the coordinate systems of the cadastral and topographic maps are the same, changes in the land boundary can be determined easily by overlaying the two maps based on the absolute coordinate system. However, if the coordinate systems of the two maps are different, then another method is required. A simple method is to translate and rotate a map based on the boundary lines of features displayed on two maps to overlay another map at the appropriate location. In this study, a cadastral map is translated and rotated on a topographic map based on boundary lines of unchanged features on two maps to determine whether a coastal land is submerged. The proposed method renders it easy to determine whether land is submerged as well as the amount of parcel area submerged.

Kim, J.O. and Lee, J.K., 2021. Urban flood inundation simulation based on high-precision 3D modeling. In: Lee, J.L.; Suh, K.-S.; Lee, B.; Shin, S., and Lee, J. (eds.), Crisis and Integrated Management for Coastal and Marine Safety. Journal of Coastal Research, Special Issue No. 114, pp. 454–458. Coconut Creek (Florida), ISSN 0749-0208.

Flooding is a frequently occurring climate-related natural disaster that affects several people worldwide. In recent years, severe natural disasters have occurred due to unusual weather, and the damage caused by such disasters has increased significantly because of high population densities and the presence of large buildings in coastal urban areas. The spatial characteristics of urban floods are becoming more complex due to widespread changes in land use, such as in the construction of buildings, roads, and drainage networks. In particular, factors that affect urban flood modeling include the location and geometry of buildings. Hydrological models can adequately simulate both surface and subsurface processes at the watershed level; however, most models cannot accurately simulate urban flooding without 3D city modeling. A 3D simulation of computation results is thus necessary for practical applications. In recent years, flood simulation technology has been used to build 3D virtual environments based on data such as high definition (HD) maps, LiDAR point clouds, and drone images. The primary objective of this study was to develop and simulate an urban flood based on 3D city modeling. The 3D city model was tested for a coastal city in the Republic of Korea. Results of case studies indicate a reasonable match between the observed and modeled flood spatial extents and highlight the importance of considering 3D city models in urban flood simulations.

Lee, J.K.; Kim, J.O., and, Oh, Y.S. 2021. Development of coastal safety mapping system by vulnerability assessment of tidal creeks. In: Lee, J.L.; Suh, K.-S.; Lee, B.; Shin, S., and Lee, J. (eds.), Crisis and Integrated Management for Coastal and Marine Safety. Journal of Coastal Research, Special Issue No. 114, pp. 459–463. Coconut Creek (Florida), ISSN 0749-0208.

Most coastal accidents occur in coastal areas with heavy traffic, or crowded beaches and tidal flats. In Korea, various leisure activities are conducted throughout the year on beaches. A significant increase in the number of coastal area workers has led to a corresponding increase in the risk of accidents; this makes the employment of effective countermeasures a necessity. A coastal safety map integrates spatial information of dangerous areas and hazards to prevent accidents in the ocean. In addition to its use for safe expansion of coastal leisure activities, coastal safety maps can be used for the prevention of disasters caused by sea conditions such as tidal creeks, heavy swells, and rip currents. In this study, a tidal creek map was created using an Unmanned Aerial Vehicle (UAV) to express the shape of a tidal creek in three dimensions. We designed and implemented a mapping system that identifies places with a high potential for human accidents in tidal flats. The system uses computer vision technology to identify the shape and location of the tidal channel and extract areas with a high probability of accidents, contributing to the development and implementation of comprehensive safety measures.

Kim, W.; Kim, S.H.; Baek, S.-I.; Kim, H., and Oh, J., 2021. A preliminary study on benthic mapping of Uljin coast based on airborne hyperspectral imagery towards the whitening detection. In: Lee, J.L.; Suh, K.-S.; Lee, B.; Shin, S., and Lee, J. (eds.), Crisis and Integrated Management for Coastal and Marine Safety. Journal of Coastal Research, Special Issue No. 114, pp. 464–468. Coconut Creek (Florida), ISSN 0749-0208.

This paper performed a preliminary investigation on the benthic identification methodology that is based on a semi-analytical optical model as a mean for detecting the whitening in the subtidal zone near Uljin, South Korea. Airborne hyperspectral images were acquired using a CASI-1500 sensor for the study area, and the preprocessing including radiometric, geometric, and atmospheric correction were applied to obtain subsurface remote sensing reflectance that is the input to the semi-analytical inversion method. Although the measured bottom reflectance was not available for the area, the experiment conducted with the typical substrate reflectance revealed the spatial distribution of bottom substrates in the area, with an implication to the whitening progress. It is concluded that a closure test with field-measured water quality variables and the collection of bottom substrate reflectance are warranted for more accurate substrate fraction estimates and the whitening detection.

Yun, K.; Lee, C.K.; He, G., and Park, B.W., 2021. Monitoring of shoreline change at Chollipo Beach in South Korea. In: Lee, J.L.; Suh, K.-S.; Lee, B.; Shin, S., and Lee, J. (eds.), Crisis and Integrated Management for Coastal and Marine Safety. Journal of Coastal Research, Special Issue No. 114, pp. 469–473. Coconut Creek (Florida), ISSN 0749-0208.

Natural coastal shorelines change constantly due to various phenomena such as tides, waves, and weather. Shoreline change data are important for coastal management, which deals with issues including coastal erosion and sedimentation trends and setbacks. It has been reported that Chollipo Beach in Taeangun, Chungnamdo, in the western part of South Korea, has been progressively sedimented over the past years. In this study, a photogrammetric analysis was conducted to determine the characteristics of the shoreline of Chollipo Beach over twenty years. In the analysis, photogrammetric aerial triangulation using old digital aerial images from 1986 and unmanned aerial vehicle images from 2020 were considered. In addition, network GPS surveying was performed for the acquisition of ground control points in the bundle adjustments stage. Finally, a digital surface model and mosaicked orthoimages were generated. For the analysis, contour lines and beach profiles were extracted. The analysis results show that over 25 years, the shorelines moved towards the sea by a maximum distance of 100 m and deposited sands reached a height of 1.84 m.

Park, S.-I.; Hwang, Y.-S.; Lee, J.-J., and Um, J.-S., 2021. Evaluating operational potential of UAV transect mapping for wetland vegetation survey. In: Lee, J.L.; Suh, K.-S.; Lee, B.; Shin, S., and Lee, J. (eds.), Crisis and Integrated Management for Coastal and Marine Safety. Journal of Coastal Research, Special Issue No. 114, pp. 474–478. Coconut Creek (Florida), ISSN 0749-0208.

There has been little research on data collection using Unmanned Aerial Vehicle (UAV) remote sensing in exploring wetland vegetation communities. The aim of this research was to integrate the concept of typical UAV remote sensing into in situ transect techniques. Transect sampling is commonly utilized to identify biological diversity and richness in vegetation communities. The Object-based Image Analysis was used to identify area-wide wetland vegetation that distinctively appears according to the UAV multispectral sensor's spectral characteristic. This study verified UAV transect mapping on wetland vegetation based on comparative evaluation between field survey and UAV transect method. This research offered an objective reference to UAV transect mapping's operational potential as the alternatives to traditional in-situ transect sampling in the coastal wetland.

Joo, S.-M. and Kim, J.-H., 2021. The effect of sea level rise on adjacent land and the resulting land value assessment method. In: Lee, J.L.; Suh, K.-S.; Lee, B.; Shin, S., and Lee, J. (eds.), Crisis and Integrated Management for Coastal and Marine Safety. Journal of Coastal Research, Special Issue No. 114, pp. 479–483. Coconut Creek (Florida), ISSN 0749-0208.

This study aims to infer the possibility of inundation of coastal areas due to sea level rise caused by climate change. In addition, it seeks to present a necessary survey method and value calculation method to be reflected on the land value. To this end, GIS spatial analysis was performed using tidal observation data and flooding maps. The analysis of IPCC sea level rise assuming the worst-case scenario (Scenario 1) and the gradual-case scenario (Scenario 2) of the actual measurement data of the Busan Tide Observatory showed that 3.8%–5.5% of the total land in Haeundae-gu will be at risk of flooding within the next 100 years. Particularly, lands with a relatively high value at present are more vulnerable. If the method of calculating flood-prone areas presented in this study is introduced in the Government's Land Characteristic Evaluation and the standard land value for areas expected to be flooded is accurately assessed, then the economic loss and social confusion caused by future sea level rises can be prevented.

Park, S.-H.; Choi, J.-G., and Cho, Y.-J., 2021. Development of a probability model for the transmission coefficient of Low Crested Breakwaters (LCB). In: Lee, J.L.; Suh, K.-S.; Lee, B.; Shin, S., and Lee, J. (eds.), Crisis and Integrated Management for Coastal and Marine Safety. Journal of Coastal Research, Special Issue No. 114, pp. 484–488. Coconut Creek (Florida), ISSN 0749-0208.

Low Crested Breakwaters (LCB) have been the most preferred structural type among many countermeasures against beach erosion. The extent of shore protection by LCB depends on transmittance coefficients, which are random due to the variability inherent in the marine environment. However, a probability model for transmittance coefficients is hard to find in the literature, indispensable for the reliability-based optimal design of LCB. In this rationale, first, a probability model of transmission coefficients is empirically developed. In doing so, transmittance characteristics of LCB were examined using the situ-wave data at the up-wave and down-wave sides of LCB at Bong-Po and Sok-Cho from 2019.8.6 to 2019.8.21 in order to identify the pertinent random variables affecting LCB transmittance. It turns out that sea wave conditions significantly affect the transmittance coefficients, and the roughness of sea wave conditions can be quantified in terms of wave height and its associated wave slope. Wave height and its associated wave slope are highly correlated in the mild sea, but they behave independently as wave heights get more enhanced. These complicated interrelations between wave height and wave slope can be described using the joint distribution of wave amplitude and its associated period by Longuet-Higgins (1983). In this rationale, we analytically derived a probability model for transmittance coefficients of LCB from the joint distribution of wave amplitude and its associated period by Longuet-Higgins (1983) and d'Angremond, van der Meer, and de Jong (1996) model using the standard technique of transformation of random variables (Papoulis, 1984). Numerical simulation shows that as sea wave conditions are getting harsh, a non-negligible probability mass shifts toward the low transmittance coefficients due to long waves appearing in the random wave field by sub-harmonic resonance wave-wave interaction, which is well-known after the studies of Hasselmann(1967) and Phillips(1980) on the development of wind waves. It was also shown that the probability mass shift toward the low transmission coefficients is accompanied by the probability mass shift toward higher transmission coefficients, which also comply with the studies of Hasselmann (1967) and Phillips (1980).

Lee, J.L. and Cho, Y.-J., 2021. Numerical analysis of sediment transport rates from rip currents at an open inlet between Low Crested Breakwaters (LCB): The role of infra-gravity waves. In: Lee, J.L.; Suh, K.-S.; Lee, B.; Shin, S., and Lee, J. (eds.), Crisis and Integrated Management for Coastal and Marine Safety. Journal of Coastal Research, Special Issue No. 114, pp. 489–493. Coconut Creek (Florida), ISSN 0749-0208.

Low Crested Breakwaters (LCB), the most preferred structural type in the coastal zone management project by the Korean Ministry of Ocean and Fisheries, has been designed to mitigate beach erosion by high waves occurring only a few times a year. Now that moderate sea conditions are dramatically different from those in rough seas, these poor design practices could interrupt the grand circulation process of natural beaches over the course of a year. As a result, the beach stabilizing effect of LCB often falls short of our expectations. In this study, in order to test this hypothesis, 3-D numerical simulation was carried out to analyze the rip currents and its associated sediment transport at the open inlet between LCB when LCB is subject to infra-gravity waves, which play an indispensable role in the beach restoring process in a mild sea with an annual prevalence rate of over 80%. Numerical results show that in the case of LCB with lower crest freeboard, rip currents gets increased by 2.6 times when compared to the one before the deployment of LCB since the water mass influx toward the down-wave side of LCB by overflowing LCB by the preceding waves is redirected toward the open inlet. The sediment transport rate was estimated using Bailard's model, the most referred cross-shore sediment model in the literature. It was shown that the primary sediment transport mode at the open inlet between LCB was bed load, and sand of 5.62 ×10^–5 m³ / m was leaving the inner zone of LCB per unit wave period.

Kim, I.-H. and Cho, Y.-J., 2021. Transmission characteristics of Low Crested Breakwaters (LCB) with an emphasis on Korean marine environments. In: Lee, J.L.; Suh, K.-S.; Lee, B.; Shin, S., and Lee, J. (eds.), Crisis and Integrated Management for Coastal and Marine Safety. Journal of Coastal Research, Special Issue No. 114, pp. 494–498. Coconut Creek (Florida), ISSN 0749-0208.

The transmission coefficient of Low Crested Breakwaters (LCB), the primary structural type among many countermeasures against beach erosion, is the crucial design factor that dictates the extent of beach protection by LCB. The models of d'Angremond, van der Meer, and de Jong (1996) and van der Meer and Daemen (1994) for the transmission coefficient have been popular since the most comprehensive hydraulic model test was used in its development. However, it is worthy of note that humongous tetrapod has been preferred as the construction material of LCB to quarry stone due to less adverse environmental impact and workability, and the porosity of LCB built with tetrapod is more significant than LCB built with the quarry stone. As a result, LCB deployed in Korea was designed to rise near the free surface to obtain target energy dissipation to mitigate beach erosion in rough seas. Based on these facts, it can be easily perceived that these construction environments differ from the one underlying d'Angremond, van der Meer, and de Jong (1996), van der Meer and Daemen (1994) model. In this rationale, this study examined the transmission characteristics of LCB at Bong-Po beach using the situ wave data collected from 2019.8.6. to 2019.8.21. In doing so, 3-D numerical simulation was also carried out to make up the wave observation system's limitations, which often malfunctioned in the rough seas. It was shown that transmission coefficients by d'Angremond, van der Meer, and de Jong (1996), van der Meer and Daemen (1994) are significantly different from the one based on the situ wave data. Several factors are involved in making this difference, and among these, the Korean construction environment mentioned above noticeably stands out. Based on this rationale, a modified transmission coefficient model optimized for the Korean construction environment was also developed, which showed a remarkable agreement with the measured data.

Kim, G.-S.; Ryu, H.-S., and Kim, S.-H., 2021. Evaluation of longshore drift on the east coast of Maengbang Beach (Gangwon, Korea) through wave and depth changes. In: Lee, J.L.; Suh, K.-S.; Lee, B.; Shin, S., and Lee, J. (eds.), Crisis and Integrated Management for Coastal and Marine Safety. Journal of Coastal Research, Special Issue No. 114, pp. 499–503. Coconut Creek (Florida), ISSN 0749-0208.

Numerical simulation of the sediment by the Delft3d model was conducted to examine the changes in the longshore drift transport caused by long-term wave changes at Maengbang Beach. Representative waves were identified with input reduction tools using NOAA NCEP wave data of about 40 years (i.e., January 1979 to May 2019). To verify the adequacy of the model, simulated wave and depth changes were compared with corresponding observed data for about 23-month period (from March 2017). Error analysis showed a bias of 0.05 and root mean square error of 0.23, indicating that the model results were satisfactory. Further, the observed and the simulated values of change in depth were similar. To examine the effects of long-term changes in wave characteristics, the NOAA wave data were classified into representative wave grades, and the annual trends of the representative waves were analyzed. After assessing the weight of each wave class considering the projected wave environment for year 2100, the amounts of sedimentation, deposition, and longshore drift transport were assessed for the same period. Sedimentation pattern would not change significantly compared to the current state, and the amount of the local longshore drift will likely decrease. While a local increase in the Longshore drift transport may occur, the overall drift and the amount of sediment movement are likely to remain at current levels. Regarding the coastal longshore drift under climate change, the study considered the average sea level rise as per scenarios RCP 2.6, RCP 6.0, and RCP 8.5 (IPCC, 2013). The net amount of sediment movement and its variability are projected to increase with the rise in sea level for most areas. Regarding the amount of sediment movement, local movement at the center of the coast will likely decrease compared to the present state, and, consequently, waves would have a greater impact on the edge due to sea level rise.

Vu, X.H. and Lee, J.L., 2021. Simulation study of scarp and berm formation using a suspended sediment transport model. In: Lee, J.L.; Suh, K.-S.; Lee, B.; Shin, S., and Lee, J. (eds.), Crisis and Integrated Management for Coastal and Marine Safety. Journal of Coastal Research, Special Issue No. 114, pp. 504–508. Coconut Creek (Florida), ISSN 0749-0208.

Beach berms and scarps are common morphological features that develop repetitively due to the cyclic incidence of mild and storm waves. However, beach scarp and berm formations, as well as their morphodynamics, have not been researched thoroughly. In particular, scarp generation is often observed at nourished beaches or under the incidence of oblique storm waves; scarps can pose severe risks to beach users and negatively impact local ecosystems. A numerical study was conducted using a suspended sediment transport model developed in a previous study to quantify the morphodynamic responses of beach berms and scarps to the foreshore region as well as offshore sand motion. In the present study, the destructive beach slope at the foreshore was controlled using Kim's empirical formula on the foreshore slope.

Sambuaga, R.D. and Lee, H.S., 2021. Optimized evacuation plan and decision support system development with agent-based modelling and GIS analysis for tsunami events in Pandeglang, Banten, Indonesia. In: Lee, J.L.; Suh, K.-S.; Lee, B.; Shin, S., and Lee, J. (eds.), Crisis and Integrated Management for Coastal and Marine Safety. Journal of Coastal Research, Special Issue No. 114, pp. 509–513. Coconut Creek (Florida), ISSN 0749-0208.

On December 22, 2018, a tsunami caused by the eruption of the volcanic mountain and partial collapse of the Mt. Anak Krakatoa (The child of Krakatoa) volcano occurred in the Sunda Strait (a strait between Java and Sumatera island), Indonesia. The tsunami in the Sunda Strait resulted in 430 casualties (January 7th, 2019). The aim of this study is to provide optimum evacuation shelters by reducing evacuation time and casualty number caused by tsunami events. Early evacuation is the most significant measure in reducing casualties in tsunami disaster. Panimbang sub-district is chosen as a study area in this research, which it has the highest casualties according to Pandeglang Regional Disaster Management Agency (BPBD Pandeglang). Digital Elevation Model (DEM), information dataset (road network, hospital, worship facilities, schools, population distribution, etc.), and casualties' information are used in the analysis. This study conducts two parts; shelter analysis and agent-based modeling. The service area evaluation of proposed shelter is conducted using network analyst tool in ArcGIS. The important variable in the shelter analysis is the nearest accessibility based on the road network from residential area to proposed shelters. Public facilities such as mosque, school, health center, etc. are used as proposed shelters in the analysis. Ages group, walking speed, travel mode (walk or driving car), etc. are used as parameters and scenarios in the agent-based model. It affects total evacuee in this model.

Cho, M.; Yoon, H.-D.; Do, K., and Kim, I., 2021. Calibration and assessment of bed evolution model in an embayed beach with submerged breakwaters. In: Lee, J.L.; Suh, K.-S.; Lee, B.; Shin, S., and Lee, J. (eds.), Crisis and Integrated Management for Coastal and Marine Safety. Journal of Coastal Research, Special Issue No. 114, pp. 514–518. Coconut Creek (Florida), ISSN 0749-0208.

An embayed beach is a common beach around the world and relatively stable over longer timescale except for high-energy wave event. A submerged breakwater is a structure that is effective in reducing coastal erosion by dissipating wave energy. Typhoon Lingling, which occurred in September 2019, affected the shoreline change in Korea. XBeach, process-based model, has been used to simulate nearshore hydrodynamics and morphological response to storm condition. XBeach has a variety of parameters, and provides default settings. However, parameter calibration is a process that must be performed to apply to a specific site. Parameter calibration has been carried out depending on the researchers' experience or through traditional trial-and-error, but more rigorous and systematic methods are required. In this study, parameter calibration in XBeach is performed for an embayed beach with submerged breakwaters under storm conditions. Seven hundred (700) parameter groups were generated using Monte-Carlo sampling and 700 simulations were performed for calibration and assessment using the Root Mean Square Error (RMSE) statistical method. The retreat distance of 20 cross-shore section extracted from the surveyed shoreline, and RMSE was calculated through comparison with the simulation results. As a result, there are difference between the default setting and the optimal setting, and the accuracy in the optimal setting was improved by about 30% compared to the default setting.

Yeon, Y.J. and Lee, J.L., 2021. Cost comparison between hard and soft approaches adapted as preventive methods of beach erosion. In: Lee, J.L.; Suh, K.-S.; Lee, B.; Shin, S., and Lee, J. (eds.), Crisis and Integrated Management for Coastal and Marine Safety. Journal of Coastal Research, Special Issue No. 114, pp. 519–523. Coconut Creek (Florida), ISSN 0749-0208.

To protect the properties behind a beach, submerged breakwater, which is a representative hard approach, or beach nourishment, which is a representative soft approach, has been performed. The submerged breakwater protects the facilities behind the beach by controlling waves to mitigate erosion. This study estimates the cost required to secure a buffer section for the wave inflow of 30-year return period using submerged breakwater and beach nourishment methods for Sokcho Beach (Sokcho-si, Gangwon-do), one of the coastal maintenance project areas, and conducts economic assessment of the two methods. For the submerged breakwater method, the construction cost was calculated using the shoreline observation data, which were observed four times a year for about 8 years. For the beach nourishment method, the construction cost was calculated using the sand loss half-life (shoreline retreat over time) considering that the nourished sands cannot be maintained. The result showed that beach nourishment could obtain a higher economic feasibility. By enhancing sand maintenance, beach nourishment was evaluated as more economical than the hard approach when the sand loss rate (k), which determines the half-life of beach nourishment, was lower than 0.167 yr^–1. Furthermore, beach nourishment is highly evaluated because it is an eco-friendly construction method, and it will be more effective when combined with other soft approaches.

Hong, S.; Dodaran, A.A.; Kim, T.; Kim, J.; Huynh, V.M.; Lee, J., and Kwon, S., 2021. Variation of irregular waves passing over an Artificial Coral Reef (ACR). In: Lee, J.L.; Suh, K.-S.; Lee, B.; Shin, S., and Lee, J. (eds.), Crisis and Integrated Management for Coastal and Marine Safety. Journal of Coastal Research, Special Issue No. 114, pp. 524–528. Coconut Creek (Florida), ISSN 0749-0208.

To investigate the variation of irregular waves due to an Artificial Coral Reef (ACR), two-dimensional experiments on the wave steepness, wave period, and relative submergence were conducted. The results for the wave transmission coefficient under ACR installation indicated that the wave steepness and period conditions are closely related to wave attenuation, which has similar trends for general coastal structures, even under irregular wave conditions. Additionally, the total spectral energy decreased gradually, whereas an inconsistent peak-energy decrement occurred with a wave steepness of 0.032, which was expected because of spectral energy redistribution due to ACR. The correlation between the relative submergence and spectral energy was investigated via a spectral analysis. In high frequency domain (1.25∼2.25f/f_p), the composition ratio of spectral energy increased with larger relative submergence, whereas opposite trend was observed in low frequency domain (0.25∼0.75f/f_p). The main findings of this study can provide basic knowledge for understanding irregular wave variation over the ACR.

Kim, T.; Kwon, Y.; Hong, S.; Kim, J.; Kwon, S., and Lee, J., 2021. Wave attenuation analysis for artificial coral reefs using a physical modelling approach. In: Lee, J.L.; Suh, K.-S.; Lee, B.; Shin, S., and Lee, J. (eds.), Crisis and Integrated Management for Coastal and Marine Safety. Journal of Coastal Research, Special Issue No. 114, pp. 529–533. Coconut Creek (Florida), ISSN 0749-0208.

Due to global warming and coastal development, the damages in coastal such as sea level rise and changes in coastline caused by scour and erosion are increasing, Various types of breakwaters are applied to prevent the coastal erosion, however, the problem such as scour around the structure is exacerbated, therefore a fundamental solution is needed. In this study, two-dimensional laboratory experiments were conducted in the wave flume to investigate the wave transmission phenomena of artificial coral reef. Experiments are conducted by analyzing wave transmission dependents on ratio of stem length to water depth(l_s/h), wave height and wave period. Wave attenuation appeared to be most dependent on stem length to water depth(l_s/h) and structure width. As incident wave height increased and the wave period decreased, the wave attenuation also increased, however, it was insignificant compared to the influence of the inundation rate. Wave attenuation increases dependents on incident wave height and period, however showed insignificant effect compared to submergence rate. In addition wave attenuation rate also affects wave energy reduction in order of l_s/h > H₀/h > h/L₀. Based on results, we analyzed correlation between KC and C_D of artificial coral reef to suggest the equation on empirical relationship. As a result, it is judged that estimating wave transmission rate and drag coefficient of artificial coral reef dependents on sectional specification can be utilized properly in working design and application.

Lim, C.; Lee, J.L., and Lee, S., 2021. Analyzing wave height and direction using the Rayleigh distribution function. In: Lee, J.L.; Suh, K.-S.; Lee, B.; Shin, S., and Lee, J. (eds.), Crisis and Integrated Management for Coastal and Marine Safety. Journal of Coastal Research, Special Issue No. 114, pp. 534–538. Coconut Creek (Florida), ISSN 0749-0208.

As erosion changes the shape of the shoreline of South Korea, many studies have been conducted to analyze the accurate shape of the shoreline. While many factors contribute to the change of the shoreline, one of the top contributing factors is the change in wave direction. However, accurate measurements of the wave direction were not possible until recently, and studies on the wave direction are insufficient compared to the studies on the wave height and period. Although long-term wave observation data is required to analyze waves, only short-term observation data is available in Korea because observation systems have been established in Korea since 2001. Therefore, the distribution characteristics of wave direction and wave height were analyzed using long-term wave hind-cast data provided by NOAA data. It is not straightforward to find regular characteristics that determine the annual average wave direction distribution from the NOAA data. However, if the wave direction is analyzed by season, an asymmetric distribution characteristic with respect to the main direction can be found. The wave directions of four seasons in the East Sea were very similar (summer: 50°/winter: 35°), while those in the West Sea were very different (summer: 205°/winter: 300°). In this study, it was assumed that the wave height and wave direction are independent of each other. Furthermore, it was also assumed that the wave height in each wave direction has the Rayleigh distribution to propose a wave height distribution function. The Rayleigh distribution function was modified by introducing the wave direction spreading coefficient, which controls the peak, and the distribution area coefficient, which reflects the energy of each wave direction component. Finally, this function was compared with NOAA data of the East Sea and West Sea of South Korea to verify the applicability.

Kim, T.K.; Jeong, J.H., and Lee, J.L., 2021. Shoreline variation analysis by cross-shore sediment transport resulting from effects of storm waves. In: Lee, J.L.; Suh, K.-S.; Lee, B.; Shin, S., and Lee, J. (eds.), Crisis and Integrated Management for Coastal and Marine Safety. Journal of Coastal Research, Special Issue No. 114, pp. 539–543. Coconut Creek (Florida), ISSN 0749-0208.

Coastal beach erosion is affected by not only the wave energy of a storm wave, but also its duration. Therefore, this study analyzes the duration characteristics for different storm wave scenarios using wave data obtained over 40 years; these data were provided by the National Oceanic and Atmospheric Administration (NOAA). Further, the vulnerability of shoreline erosion deduced from the correlation between the cumulative breaking wave energy and observed shoreline variability was discussed. To analyze the duration of storm wave scenarios, we propose dimensionless characteristics for peak wave height per storm wave scenario and a representative mathematical function for storm wave scenarios. Shoreline variability is calculated using the shoreline survey data for Bongpo Beach, located on the eastern coast of South Korea, measured quarterly for nine years. The cumulative breaking wave energy flowing into the beach generally exhibited a linear relationship with the shoreline variability. Therefore, this study suggests a simple method to determine the extent to which the shoreline retreats given the peak wave height of the incoming wave scenario.

Muin, M., 2021. Sediment dispersion modeling of a non-orthogonal boundary fitted technique: Mangrove reclamation to protect cliff erosion in Bintuni Bay, Indonesia. In: Lee, J.L.; Suh, K.-S.; Lee, B.; Shin, S., and Lee, J. (eds.), Crisis and Integrated Management for Coastal and Marine Safety. Journal of Coastal Research, Special Issue No. 114, pp. 544–548. Coconut Creek (Florida), ISSN 0749-0208.

Bintuni Bay is a semi-closed bay located in West Papua Province, Indonesia. The facility of Tangguh LNG Project was faced serious problems due to erosion along the cliff. It was decided that reclamation is the best solution. Mangrove trees are planted in the reclamation area to reduce the wave. The reclamation was designed until one meter below highest water spring to allow seawater to flow in and out through the inlet/outlet. This paper presents and discusses simulations for several options of reclamation layout, inlet/outlet, during and after reclamation. MuSed3D, the 3D ocean hydrodynamics and sediment transport model using non-orthogonal boundary fitted technique, was employed to conduct the simulation.

Kim, K.S. and Lee, J.H., 2021. A simulation of soil dumping using moving particle semi-implicit method. In: Lee, J.L.; Suh, K.-S.; Lee, B.; Shin, S., and Lee, J. (eds.), Crisis and Integrated Management for Coastal and Marine Safety. Journal of Coastal Research, Special Issue No. 114, pp. 549–553. Coconut Creek (Florida), ISSN 0749-0208.

Soil dumping is one of most important problems on the coastal and ocean construction project. In general, the computational fluid dynamics method used grid system to simulate soil particle under flow with concentration. It can be useful for fast calculation; however, it is restricted to demonstrate its movement. The Moving Particle Semi-implicit (MPS) method follows fully Lagrangian approach, thus it can simulate soil particle behavior due to tracking each particle. In this study, the newly developed MPS method modified for solid particle was used to simulate soil dumping. For the solid particle interaction, drag force and friction force term were implemented instead of viscosity term in the governing equation. The friction force is due to friction between solid particles, and the drag force can be calculated by relative velocity around center particle within effective range. All the solid particle interaction models were validated by corresponding physical phenomena. The numerical results were compared to the corresponding experimental results and they show good agreement in the tendency of behavior.

Lee, J.-H. and Koo, B., 2021. Numerical study of non-linear wave run-up around a circular cylinder in regular waves. In: Lee, J.L.; Suh, K.-S.; Lee, B.; Shin, S., and Lee, J. (eds.), Crisis and Integrated Management for Coastal and Marine Safety. Journal of Coastal Research, Special Issue No. 114, pp. 554–558. Coconut Creek (Florida), ISSN 0749-0208.

In this study, numerical simulations have been carried out to investigate the non-linear wave run-up phenomena of a single cylinder according to wave period and slope. In order to perform numerical analysis on a three-dimensional incompressible viscous turbulent two phase flow, this study used a Volume Of Fluid (VOF) technique and a realizable turbulence model based on the Computational Fluid Dynamics (CFD) commercial code, “STAR-CCM+”. Various incoming wave conditions have been applied to see how the wave steepness and wave periods affect the wave run-up height on the circular cylinder. Finally, the wave run-up estimation results for wave slopes and periods were compared with the related experimental results and they had good agreement. It was confirmed that as the wave steepness increased, the run-up phenomenon appeared largely at the part where the cylinder hit the incident wave.

Koo, B. and Kang, Y.-D., 2021. Numerical analysis on wave breaking around a wedge-shaped bow. In: Lee, J.L.; Suh, K.-S.; Lee, B.; Shin, S., and Lee, J. (eds.), Crisis and Integrated Management for Coastal and Marine Safety. Journal of Coastal Research, Special Issue No. 114, pp. 559–563. Coconut Creek (Florida), ISSN 0749-0208.

Numerical study has been performed to investigate the flow characteristics such as wave breaking process and small scale features of ship bow waves. The geometry of wedge-shaped bow used in the present study is from one of previous studies (Waniewski, Brennen, and Raichlen, 2002) and the condition of calculation is with Re = 1.64×10⁵ and Fr = 2.93. Star CCM+, one of commercial CFD softwares, has been used to perform the numerical simulations. Results such as overall bow wave profile, plunging jet shape, air entrainment, and wave breaking process have been compared with other experimental and numerical studies and discussed some discrepancies with others.

Lee, K.-W.; Byun, T.Y., and Kim, M.-C., 2021. Flow analysis of ship scrubber effluent. In: Lee, J.L.; Suh, K.-S.; Lee, B.; Shin, S., and Lee, J. (eds.), Crisis and Integrated Management for Coastal and Marine Safety. Journal of Coastal Research, Special Issue No. 114, pp. 564–568. Coconut Creek (Florida), ISSN 0749–0208.

Sulfur oxide is one of the three major air pollutants that cause acid rain. Ships contribute to approximately 13% of sulfur oxide emissions. Due to this, concerns have been raised regarding the poor air quality in port cities. Hence, the problem of sulfur oxide emission must be solved on priority. The International Maritime Organization (IMO) under the United Nations decided to significantly strengthen the regulation of sulfur content standards for marine fuel oil. The percentage of sulfur in oil should be reduced to below 0.5% from the previous value of 3.5% by the year 2020. Liquefied Natural Gas (LNG) might be a good option for the reduction of sulfur initially; however, the abrupt change from diesel to LNG is difficult due to its cost. Scrubber is another comparatively economical option to remove sulfur through chemical reactions. There is, however, a side effect: when sulfur oxides are mixed with washing water, they cause the water to turn acidic. The acidity (pH) of the discharged water is regulated by MEPC.259(68), as this acidic washing water might affect marine organisms. This study investigates the extent of effluent dilution due to variation of outlet pipe size, angle, and presence of different diffusers using computational fluid dynamics analysis.

Byun, T.Y.; Lee, K.W.; Kim, J.W., and Kim, M.C., 2021. Comparative study on the performance of a twisted rudder with wavy configuration. In: Lee, J.L.; Suh, K.-S.; Lee, B.; Shin, S., and Lee, J. (eds.), Crisis and Integrated Management for Coastal and Marine Safety. Journal of Coastal Research, Special Issue No. 114, pp. 569–573. Coconut Creek (Florida), ISSN 0749-0208.

Because of recent serious human injuries and marine pollution caused by ship accidents, interest in maneuverability of ships has been increasing. In addition, because the International Maritime Organization (IMO) mandates the adoption of Energy Efficiency Design Index (EEDI), which is a total carbon dioxide regulation system, the demand for eco-friendly ships has increased. The energy saving device in the stern direction based on the propeller is called a post device, and most post devices are based on rudders. Various special rudders have been introduced to reflect this interest in eco-friendliness and steering safety. In this study, to confirm the ship applicability of a twisted rudder with wavy configuration, we reviewed the ship resistance, self-propulsion, and maneuverability. The target ship for analysis and experiment was a KRISO container ship, and the performance of Wavy Twisted Rudder (WTR) was compared and verified with a fishtail rudder, which is an existing special rudder. A Computational Fluid Dynamics (CFD) analysis was conducted using Star CCM+ ver.11.02, and it was computed using the Reynolds-Averaged Navier-Stokes (RANS) equation as the governing equation for turbulent flow analysis around the hull. The verification result revealed that the maneuverability of the proposed rudder was slightly lower than that of the existing special rudders. However, the maneuverability sufficiently satisfied the IMO standards and demonstrated improved results in terms of efficiency.

Adibhusana, M.N.; Lee, J.-I., and Ryu, Y., 2021. Wave overtopping plunging on the rear side of composite breakwater. In: Lee, J.L.; Suh, K.-S.; Lee, B.; Shin, S., and Lee, J. (eds.), Crisis and Integrated Management for Coastal and Marine Safety. Journal of Coastal Research, Special Issue No. 114, pp. 574–578. Coconut Creek (Florida), ISSN 0749-0208.

In this study the behavior of overtopping water falling on the rear side of composite breakwater were investigated through physical experiment. A series of regular wave with various wave period and wave height were used as wave parameters while velocity at the rear edge of breakwater, plunging location, and plunging velocity were used as the parameters of wave overtopping behavior on the rear side of composite breakwater. The geometry of the composite breakwater was kept constant through the experiment. The Bubble Image Velocimetry (BIV) and digital image analysis were applied to measure the velocity in the aerated region of overtopping water falling on the rear side of breakwater and the plunging location. The rear edge velocity was linearly increased as the wave parameter increased. The increment value of plunging location shows a logarithmic trend as wave period and wave height increased. The front velocity of overtopping flows right before plunging the rear water surface shows a linear trend with those wave parameters.

Kang, Y.-D. and Koo, B., 2021. Experimental study of energy contribution by coherent structures in a turbulent boundary layer. In: Lee, J.L.; Suh, K.-S.; Lee, B.; Shin, S., and Lee, J. (eds.), Crisis and Integrated Management for Coastal and Marine Safety. Journal of Coastal Research, Special Issue No. 114, pp. 579–583. Coconut Creek (Florida), ISSN 0749-0208.

An experimental study was carried out to investigate a contribution of large coherent structures in turbulent flow. Both dynamometer and Clauser fitting method were adopted to calculate the frictional velocity near the wall having uncertainty. In order to quantify coherent structures, Particle Image Velocimetry (PIV) system was used to reveal their characteristics connecting through boundary layer. Variable Interval Time Averaging (VITA) technique scanned through flow fluctuations at the edge of boundary layer, whether there was a large deviation from the background flow. According to the presence of large scale structures, the flow field was divided into weak and strong cases to validate their existence. Changing a free-stream velocity from 0.5 m/s to 1.0 m/s increased the Reynolds stress more than 3 times. Proper Orthogonal Decomposition (POD) analysis was also applied to compare the energy budgets between them.

Lee, W.D.; Choi, S.; Hwang, T.; Park, J.R., and Hur, D.S., 2021. Experimental study on the correlation between wave overtopping and reflection over an absorbing revetment: Non-breaking wave Conditions. In: Lee, J.L.; Suh, K.-S.; Lee, B.; Shin, S., and Lee, J. (eds.), Crisis and Integrated Management for Coastal and Marine Safety. Journal of Coastal Research, Special Issue No. 114, pp. 584–588. Coconut Creek (Florida), ISSN 0749-0208.

This study performed a hydraulic model experiment to analyze the correlation between wave overtopping and reflection over an absorbing revetment in regular wave fields without wave breaking. Regular waves that last 1.2–2 s and 1.0–2.6 cm high were generated in a two-dimensional wave tank with a depth of 50 cm. With respect to the experimental conditions, an absorbing revetment with two layers of Tetrapods (TTPs) installed on a foundation mound of sand stone was considered. To calculate the reflection coefficient, the time waveform measured using the wave gauges was substituted into a two-point method to separate the incident and reflected waves, while the overtopping rate was directly measured in a separate overtopping tank. According to the experimental results, the water surface waveform in front of the revetment differed depending on the presence of wave overtopping. Under the overtopping condition, the water level in front of the revetment increased and then gradually decreased. Under the non-overtopping condition, the water level continuously increased and then quickly decreased. With respect to wave reflection, under the non-overtopping condition, the reflection coefficient increased as the surf similarity parameter increased. Under the overtopping condition, the distribution of the reflection coefficient was below a certain level and exhibited no clear trend. As the surf similarity parameter increased, the water level at the time of wave overtopping increased. In addition, the longer the duration of wave overtopping, the greater the overtopping rate was. According to the analysis of the correlation between wave overtopping and wave reflection within the same period, the reflection coefficient generally decreased as the overtopping rate increased. However, this phenomenon was not observed in any of the experimental results.

Kang, C.; Lee, W.D.; Kim, T.; Lee, T.K., and Hong, S., 2021. Behavior of multiple blocks mounted underwater using fluid-structure interaction and contact analysis. In: Lee, J.L.; Suh, K.-S.; Lee, B.; Shin, S., and Lee, J. (eds.), Crisis and Integrated Management for Coastal and Marine Safety. Journal of Coastal Research, Special Issue No. 114, pp. 589–593. Coconut Creek (Florida), ISSN 0749-0208.

This study discusses a method for estimating the structural stability of a coastal concrete structure with an emphasis on sliding and overturning due to tidal current or waves. Because of the complexity of fluid flow behavior, a coastal structure was assumed to be a rigid body for structural safety reviews. Namely, the safety reviews assume the stress and strain of a structure insignificant and focus only on the fluid analysis. However, a structural analysis should be considered especially if the structure is not of single, large block construction, such as artificial reef blocks, which are stacked on each other. An artificial reef is normally composed of small concrete blocks stacked together. A section of each block is relatively small and interacts with each other blocks. Macro issues, such as sliding and over-turning as well as micro issues such as stress concentration and contact between blocks must be considered. This study emphasizes the microstructural point of view, such as the stress and strain of each artificial block and the interaction between blocks. ABAQUS 2D fluid-structure interaction analysis was performed where the simultaneous analysis was completed using computational flow dynamics; in addition, the performance of a structural analysis using finite element modeling.

Maharta, I.P.R.F.; Radjawane, I.M.; Suprijo, T.; Park, H., and Hendrawan, I.G., 2021. Identification of marine debris sources in Kuta Beach, Bali, Indonesia. In: Lee, J.L.; Suh, K.-S.; Lee, B.; Shin, S., and Lee, J. (eds.), Crisis and Integrated Management for Coastal and Marine Safety. Journal of Coastal Research, Special Issue No. 114, pp. 594–598. Coconut Creek (Florida), ISSN 0749-0208.

Kuta Beach is one of the beaches with the biggest tourist arrivals in Bali. In recent years Kuta beach has received shipments of marine debris from the Bali Strait. Kuta Beach area gets an average of piles of marine debris reaching ± 30 tons/day and the peak occurred in January 2014 which reached ± 1,700 tons. Previous studies only carried out simulations with sources of marine debris from outside the Bali Strait and the coast in Bali. This study aims to determine the marine debris that reaches Kuta Beach with the source of debris from rivers in the west season (January 2019). The Finite Volume Coastal Ocean Model (FVCOM) is used to obtain the circulation of current patterns and patterns of movement of particles by using the Lagrangian Particle Tracking module, with the sources of the debris from 8 river in Bali Strait. In general, the pattern of movement of currents in the Bali Strait at west season is dominantly moving towards the east due to the influence of the west monsoon winds. The simulation results show that particles that reach Kuta Beach are dominated by rivers that flow near Kuta Beach, with the river that gives the most debris is the Tukad Penet, which is 68.89% of the total marine debris that reaches Kuta Beach.

Rachmayani, R.; Ningsih, N.S.; Ardiansyah, I.; Yani, L.F.; Rizal, A.M.; Kartadikaria, A.R.; Sari, N.T, and Park, H., 2021. Utilization and linkage of oceanic energy in Natuna Island: A review. In: Lee, J.L.; Suh, K.-S.; Lee, B.; Shin, S., and Lee, J. (eds.), Crisis and Integrated Management for Coastal and Marine Safety. Journal of Coastal Research, Special Issue No. 114, pp. 599–603. Coconut Creek (Florida), ISSN 0749-0208.

Natuna Regency is known as the northernmost regency in the Karimata Strait with its abundant captured fisheries up to 104.879,81 tons, oil up to 3.138.143 barrels and natural gas up to 34.772.019 MMBTU in 2019, respectively. Moreover, Natuna is famous for aquaculture fisheries of Napoleon (Cheilinus undulatus) with allowed-export capacity up to 30,000 kg. However, resource development in Natuna is often constrained by poor infrastructure such as limited fish unloading berths and natural gas pipelines, obscure electricity, and inadequate energy resources. Thus, the utilization of resources in Natuna has not been maximized. Currently, Natuna has been partially improved on distribution services through the sea toll and the establishment of the Integrated Marine and Fisheries Centre (SKPT) of the Lampa Strait. To carry out the challenge and manifest the resources in Natuna, researches on marine renewable energy in Natuna have been conducted and revealed significant wave height up to ∼1.5 m, ocean current velocity per year ranged from 0.255 to 0.340 m/s, and thermal gradient's Carnot efficiency up to 0.67. Despite these lacking numbers on ocean currents, waves, and thermal gradients for renewable energy development, this study exhibits that the Natuna region has a great energy potential from wind farm and solar power plant development. There are four recommended sites namely Pulau Tiga, Sabang Mawang, Sedanau Island, and SKPT Natuna as places to develop hybrid renewable energy development from pumped hydro storage system, wind farm, and/or solar power plant. The renewable energy development at these locations will support smart city concept in Natuna.

Jung, B.-K. and Lee, N.-U., 2021. Analyzing the current status and challenges of coastal and inshore fisheries: A review of the impacts and the legislative improvements. In: Lee, J.L.; Suh, K.-S.; Lee, B.; Shin, S., and Lee, J. (eds.), Crisis and Integrated Management for Coastal and Marine Safety. Journal of Coastal Research, Special Issue No. 114, pp. 604–608. Coconut Creek (Florida), ISSN 0749-0208.

This study analyzed and reviewed the current status and challenges of coastal and inshore fisheries, which have the greatest impact on the continuous use of fishery resources and the protection and management of the marine ecosystem, and recommended measures to address such challenges. In particular, among the coastal and inshore stationary fishing boats and fisheries in the southern waters of South Korea, the current conditions and problems of gill net and fish trap fishery were analyzed by comparing them with the current fishing regulation system. Using a training ship, the waters where a large amount of fishing work involving coastal and inshore fishing vessels is being done were classified into A, B, and C and the waste fishing gears deposited in such waters were investigated in terms of their trawling means. In addition, the marine debris that was collected was directly identified.Through such practical field surveys and comparative analyses of the relevant information aimed at preventing disputes over fishing in coastal and inshore waters (which have been diverse and continuously occurring) as well as over the creation of waste fishing gears caused by deliberate or environmental factors, and their consequent adverse effects on the fishery resources ecosystem, this study presents a legislative improvement plan that could achieve the sustainable use of fishery resources and thus, promote the growth and development of fisheries in South Korea.

Jang, S.-H. and Kim, S.-G., 2021. Examining rescue attempts after scuba diving accidents in South Korea: Causes and strategies. In: Lee, J.L.; Suh, K.-S.; Lee, B.; Shin, S., and Lee, J. (eds.), Crisis and Integrated Management for Coastal and Marine Safety. Journal of Coastal Research, Special Issue No. 114, pp. 609–613. Coconut Creek (Florida), ISSN 0749-0208.

The purpose of this study was to examine rescue attempts after scuba diving accidents in South Korea to understand the causes and contexts of the accidents and to propose alternative strategies. To this end, we collected and reviewed local and international literature alongside accident statistics data from the Korea Coast Guard and conducted interviews with eight people, including scuba diving instructors, coast guard rescue personnel, and leisure scuba divers. According to the results of the analysis, the accidents could be divided into injuries and deaths. Injuries included “rapid ascent,” “diving in unsafe conditions,” and “drifting,” and the causes or contexts included “insufficient education,” “Korean diving culture,” and “unplanned diving.” Deaths included “collecting accidents,” “entanglement in ghost nets,” and “disappearance,” and the causes or contexts included “poor underwater environment” and “solo diving.” Based on this analysis of accident rescue, we propose “planned diving,” the “use of local guides,” and “buddy diving” as the core strategies to reduce accidents. Thus, our study provides basic data to help understand the rescue of scuba diving accident victims in South Korea and to help avoid accidents.

Lee, W.D.; Kang, C.; Hong, S.; Lee, T.K., and Lee, J., 2021. Effect of wave load on decompression of underwater workers: CFD-VPM simulation. In: Lee, J.L.; Suh, K.-S.; Lee, B.; Shin, S., and Lee, J. (eds.), Crisis and Integrated Management for Coastal and Marine Safety. Journal of Coastal Research, Special Issue No. 114, pp. 614–618. Coconut Creek (Florida), ISSN 0749-0208.

Hydrodynamic pressure from cyclic wave action causes water pressure increases and vibration, and these pressure changes can have a significant impact on underwater workers in high-pressure environments. This study investigated the impact of wave loading on decompression procedures for underwater workers using a coupled CFD-VPM. Computational Fluid Dynamics (CFD) were used to simulate wave propagation, and the Varying Permeability Model (VPM) was used to simulate the dive profile. Results of the wave propagation simulation showed that wave height and nonlinearity increased due to shoaling when approaching a beach, and the period was shortened. The maximum dynamic pressure head exceeded 1 m at depths less than 45 m and reached 10.3 m at a depth of 3 m. Simulations of the dive profile revealed that decompression time increased by 11 m and 9 s (28.36 %) under extraordinary wave conditions when underwater work was performed for 2 hours at a depth of 20 m. Furthermore, decompression time increased by 12 min and 40 s (10 %) at a working depth of 30 m. For safe underwater work operations under extraordinary wave conditions, decompression procedures should account for the pressure rise and vibration caused by wave action.

Kim, Y.-S.; Ryu, J.-H., and Lee, H.-T, 2021. A study on buoyancy maintenance time and underwater weight according to changes in lying-down posture during coastal safety education. In: Lee, J.L.; Suh, K.-S.; Lee, B.; Shin, S., and Lee, J. (eds.), Crisis and Integrated Management for Coastal and Marine Safety. Journal of Coastal Research, Special Issue No. 114, pp. 619–622. Coconut Creek (Florida), ISSN 0749-0208.

In this research, an experiment was performed to calculate body weight data and mass data for the subject's supine position using a three-dimensional image analysis program and an underwater weighing machine. This is to raise people's awareness of maritime safety and to revise the guidelines for maritime safety education by preparing institutional policies. First, the buoyancy retention time according to the change in lying down posture was the longest in P1(head-up), and in the order of P2(horizontal) and P3(attention) with statistically significant difference. Second, the change in body weight (buoyancy) according to the change of the lying down position was found to be the heaviest in P3, followed by P2 and P1 with significant difference. Summarizing the results of this study, the best way to maintain the buoyancy according to the change in lying down position during survival swimming is P1 that allows the body to float on the surface for the longest time. It also showed the heaviest underwater weight at P3, so it was found that incorrect upper body stance during survival swimming could affect buoyancy, survival rate. Lastly, even a person who is proficient in swimming has a very limited survival time at low temperatures, so it is considered that the above-mentioned efficient floating method and continuous swimming and application in education are necessary.

Kim, S.-G., 2021. Measures to improve the Korean national lifeguard qualification system: A qualitative review. In: Lee, J.L.; Suh, K.-S.; Lee, B.; Shin, S., and Lee, J. (eds.), Crisis and Integrated Management for Coastal and Marine Safety. Journal of Coastal Research, Special Issue No. 114, pp. 623–627. Coconut Creek (Florida), ISSN 0749-0208.

Maritime distress incidents requiring lifesaving interventions are increasing annually in Korea. This study aimed to compare and analyze two current Korean systems: “lifeguard” and “national lifeguard” systems —the latter established in 2017—to search for areas that need improvement and propose revision measures using a literature analysis on the qualification system and in-depth interviews with eight experts. Qualitative analysis of the interviews and literature review resulted in five suggested improvement measures. First, for an effective qualification training system, training and evaluation sites must be diversified; clauses on marine practice must be added to the qualification procedure. Second, the current qualification system lacks specific age requirements and must be revised to reflect the appropriate age for practicing lifeguards. Third, a curriculum and evaluation must be introduced to train specialized national lifeguard instructors. Fourth, the current qualification system must be revised to integrate lifeguard and national lifeguard systems and classify national lifeguards as class 1 and other lifeguards as class 2. Fifth, broader acknowledgment of the national qualification would encourage lifeguards to utilize such qualifications to find employment. The data and recommendations produced by this study may be important to the ongoing development of the national qualification system for lifeguards in Korea.

Kim, N.-G. and Lee, J.-H., 2021. Improvement of the qualification system for lifeguards. In: Lee, J.L.; Suh, K.-S.; Lee, B.; Shin, S., and Lee, J. (eds.), Crisis and Integrated Management for Coastal and Marine Safety. Journal of Coastal Research, Special Issue No. 114, pp. 628–632. Coconut Creek (Florida), ISSN 0749-0208.

The purpose of this study is to propose improvement measures for the training and evaluation problems along with institutional problems of the lifeguard qualification system in Korea. To this end, a literature research was conducted on the qualification system along with previous domestic and overseas studies, and the Delphi method was used twice on 20 water safety experts. Consequently, first, the following priorities were proposed as an improvement plan for lifeguard training and evaluation: the reinforcement of the evaluation criteria of the equipment-based rescue to improve the rescue efficiency as the first priority, strengthening of the training and evaluation centered on the professional rescue techniques as the second priority, establishment of standardized training guidelines and evaluation indicators through exchanges among the 13 lifeguard educational institutions as the third priority, introduction of training and evaluation using specialized equipment in the field of first aid as the fourth priority, introduction of the marine practice after obtaining the qualification as the fifth priority, introduction of the evaluation method considering the environmental characteristics as the sixth priority, and introduction of the physical fitness test as the seventh priority. Second, the following priorities were proposed for improving the lifeguard system: the reorganization of the qualification system through integration with national lifeguard and establishment of a lifeguard qualification system monitoring institution as the first and second priorities, respectively, reinforcement of the pre-assessment system prior to participation in the qualification course as the third priority, the selection of the National Competency Standards (NCS) occupational group of the lifeguards as the fourth priority, annual re-evaluation of the educational institutions as the fifth priority, and confirmation of compliance with the training course by the educational institutions as the sixth priority.

Kim, S.-G. and Lim, S.-M., 2021. A development plan for the beach lifeguard system in Korea. In: Lee, J.L.; Suh, K.-S.; Lee, B.; Shin, S., and Lee, J. (eds.), Crisis and Integrated Management for Coastal and Marine Safety. Journal of Coastal Research, Special Issue No. 114, pp. 633–636. Coconut Creek (Florida), ISSN 0749-0208.

This study aims to examine the problems of the beach lifeguard system in Korea and provide a plan to resolve safety and other issues faced by beachgoers and improve rescue activities. To this end, data on rescue and relevant laws were collected, and in-depth interviews were conducted with 10 lifeguards from different regions. The analysis results reveal that the beach lifeguard system in Korea requires the following improvements: First, administrative governance must be established for the coexistence of the public and private sectors. Second, it is necessary to promote public confidence in the lifeguard training system. Third, the work environment of lifeguards must be improved. The important findings and data from this study can be used to develop an effective lifeguard system in charge of beach safety.

Kim, K.-B.; Oh, C.; Ji, J.-G.; Choi, K.-H.; Kim, E.-J., and Nam-Jo, S.K., 2021. Development of survival swimming programs for people with disabilities. In: Lee, J.L.; Suh, K.-S.; Lee, B.; Shin, S.; and Lee, J. (eds.), Crisis and Integrated Management for Coastal and Marine Safety. Journal of Coastal Research, Special Issue No. 114, pp. 637–641. Coconut Creek (Florida), ISSN 0749-0208.

This study advocates for the development of a survival swimming program for people with disabilities by examining survival swimming training in Korea and other countries. As the memory of the MV Sewol tragedy is still vivid, the need for appropriate safety protocols, including swimming for survival in the event of a disaster, is clear. Government officials and related industry professionals must develop more comprehensive maritime safety protocols. Survival swimming programs are available in schools and to the public. Although prior research has examined the importance of these programs, no studies have been conducted on survival swimming programs for people with disabilities, who may learn these techniques to save their lives in times of crisis and enjoy safe leisure activities in the water. This study suggests the following: First, the focus of swimming programs in Korea should be on survival and safe swimming. Second, survival swimming education should be required by law. Third, it is necessary to develop swimming programs and guidelines for people with disabilities and to standardize them by creating detailed and specialized programs. Survival swimming programs for both the general public and people with disabilities must meet global standards and carefully consider participants' disability status and specific environmental factors of the programs' locations.