Pub Date : 2022-07-30DOI: 10.20481/kscdp.2022.9.3.171
Yejin Hwang, K. Do, Jin-Yong Jeong, Eunju Lee, Sungwon Shin
Ocean Research Station is a comprehensive ocean research infrastructure built to collect and provide real-time data with state-of-the-art observation systems. This station operates various research facilities, and the data is actively used for research in each field. In particular, since wave data is produced through the remote-sensing observation method, they are valuable as observation data. Unlike the direct observation method, they can stably collect data and store long-term observation data on severe weather. However, there is a limitation that outlier may occur due to the process of measuring and collecting data or the effects of temporary environmental changes. This study improves the remote wave data quality of MIROS RangeFinder installed at the Socheongcho Ocean Research Station using an algorithm and confirms the reliability by comparing it with the wave buoy observation data operated by the Korea Meteorological Administration. The algorithm used is a Spike removal median filter, which is applied after adjusting the conditions and variables according to the characteristics of the Socheongcho wave data. Also, we developed a new filter using a variable threshold to increase the outlier detection rate. As a result, the final algorithm shows a high outlier detection rate, but some outliers are still not removed, so improvements are required to enhance the algorithm’s performance. In addition, continuous research on the remote-sensing wave observation method is required to compensate for the limitation that the accuracy is slightly lower than that of the direct observation method.
{"title":"Algorithm Development for Quality Control of RangeFinder Wave Time Series Data at Ocean Research Station","authors":"Yejin Hwang, K. Do, Jin-Yong Jeong, Eunju Lee, Sungwon Shin","doi":"10.20481/kscdp.2022.9.3.171","DOIUrl":"https://doi.org/10.20481/kscdp.2022.9.3.171","url":null,"abstract":"Ocean Research Station is a comprehensive ocean research infrastructure built to collect and provide real-time data with state-of-the-art observation systems. This station operates various research facilities, and the data is actively used for research in each field. In particular, since wave data is produced through the remote-sensing observation method, they are valuable as observation data. Unlike the direct observation method, they can stably collect data and store long-term observation data on severe weather. However, there is a limitation that outlier may occur due to the process of measuring and collecting data or the effects of temporary environmental changes. This study improves the remote wave data quality of MIROS RangeFinder installed at the Socheongcho Ocean Research Station using an algorithm and confirms the reliability by comparing it with the wave buoy observation data operated by the Korea Meteorological Administration. The algorithm used is a Spike removal median filter, which is applied after adjusting the conditions and variables according to the characteristics of the Socheongcho wave data. Also, we developed a new filter using a variable threshold to increase the outlier detection rate. As a result, the final algorithm shows a high outlier detection rate, but some outliers are still not removed, so improvements are required to enhance the algorithm’s performance. In addition, continuous research on the remote-sensing wave observation method is required to compensate for the limitation that the accuracy is slightly lower than that of the direct observation method.","PeriodicalId":326564,"journal":{"name":"Korea Society of Coastal Disaster Prevention","volume":"51 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-07-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130031303","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2022-04-30DOI: 10.20481/kscdp.2022.9.2.123
H. Park, T. Jung
The initial waveform of the tsunami is determined by fault parameters such as the width and the length of the fault, the strike angle, the dip angle, the slip angle, the vertical distance from the seabed to the fault, and the displacement. Consequently, the tsunami run-up height is changed for various characteristics of the incoming tsunami waves. In this study, we present the analysis of the effect of fault parameters on the maximum tsunami height. The maximum tsunami height was calculated by altering the fault parameter in the tsunami numerical model and the parameter sensitivity to the maximum tsunami height was demonstrated. The depth of the fault did not significantly affect the maximum tsunami height, but the angle and the displacement are related to the maximum tsunami height. Furthermore, the strike angle and the slip angle have significant effects on the maximum tsunami height.
{"title":"Sensitivity Analysis of Fault Failure Parameters to the Maximum Tsunami Heights","authors":"H. Park, T. Jung","doi":"10.20481/kscdp.2022.9.2.123","DOIUrl":"https://doi.org/10.20481/kscdp.2022.9.2.123","url":null,"abstract":"The initial waveform of the tsunami is determined by fault parameters such as the width and the length of the fault, the strike angle, the dip angle, the slip angle, the vertical distance from the seabed to the fault, and the displacement. Consequently, the tsunami run-up height is changed for various characteristics of the incoming tsunami waves. In this study, we present the analysis of the effect of fault parameters on the maximum tsunami height. The maximum tsunami height was calculated by altering the fault parameter in the tsunami numerical model and the parameter sensitivity to the maximum tsunami height was demonstrated. The depth of the fault did not significantly affect the maximum tsunami height, but the angle and the displacement are related to the maximum tsunami height. Furthermore, the strike angle and the slip angle have significant effects on the maximum tsunami height.","PeriodicalId":326564,"journal":{"name":"Korea Society of Coastal Disaster Prevention","volume":"16 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-04-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125140877","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2022-04-30DOI: 10.20481/kscdp.2022.9.2.157
Yoon-Ji Kim, Jeong-Seok Lee, Gil-Yong Kong, Ik-Soon Cho
ECDIS provides safety function related to depth and contour lines to prevent grounding of ship. However, since the most ENCs contain depth contours at intervals of 2, 5, 10, 20, 30m, it is difficult to provide precise information to users and have limitations as a function of anti-grounding. Recently, the IHO recognized this problem and recommended the production of HD(High Density) ENC that provides depth contours at 1m intervals in confined water. In this study, spatial analysis was performed based on AIS and marine accident data to determine the depth contour ranges and areas required for HD ENC production. The study area was selected near Incheon and Pyeongtaek port on the west coast of Korea and depth contour lines with 1m intervals were created based on the TIN(Triangulated Irregular Network) interpolation algorithm and DEM(Digital Elevation Model) using the water depth data of the digital nautical chart. After that, the distribution of ship’s draft was analyzed based on the AIS data, and the spatial autocorrelation analysis using marine accident data indicates the need to provide dense contour lines in the fairway of Incheon and Pyeongtaek. It is expected to HD ENC that reflects the environment of the area and the characteristics of ships can help safe navigation of ships and prevent marine accidents.
{"title":"A Study on the Creation of High Density Depth Contours in Coastal Waters using Spatial Analysis based on Depth and AIS Data","authors":"Yoon-Ji Kim, Jeong-Seok Lee, Gil-Yong Kong, Ik-Soon Cho","doi":"10.20481/kscdp.2022.9.2.157","DOIUrl":"https://doi.org/10.20481/kscdp.2022.9.2.157","url":null,"abstract":"ECDIS provides safety function related to depth and contour lines to prevent grounding of ship. However, since the most ENCs contain depth contours at intervals of 2, 5, 10, 20, 30m, it is difficult to provide precise information to users and have limitations as a function of anti-grounding. Recently, the IHO recognized this problem and recommended the production of HD(High Density) ENC that provides depth contours at 1m intervals in confined water. In this study, spatial analysis was performed based on AIS and marine accident data to determine the depth contour ranges and areas required for HD ENC production. The study area was selected near Incheon and Pyeongtaek port on the west coast of Korea and depth contour lines with 1m intervals were created based on the TIN(Triangulated Irregular Network) interpolation algorithm and DEM(Digital Elevation Model) using the water depth data of the digital nautical chart. After that, the distribution of ship’s draft was analyzed based on the AIS data, and the spatial autocorrelation analysis using marine accident data indicates the need to provide dense contour lines in the fairway of Incheon and Pyeongtaek. It is expected to HD ENC that reflects the environment of the area and the characteristics of ships can help safe navigation of ships and prevent marine accidents.","PeriodicalId":326564,"journal":{"name":"Korea Society of Coastal Disaster Prevention","volume":"23 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-04-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127779760","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2022-04-30DOI: 10.20481/kscdp.2022.9.2.145
Daegun Kim, Eun-ji Kang, Ik-Soon Cho
Most of the domestic car ferries departing from Jeju Port in Korea were replaced through the construction of new ships or the introduction of new used ships starting in 2018 after the Sewol Ferry accident. Amid this trend of ship replacement, the size of passenger ship has also become larger than in the past to increase passenger sales and cargo transportation profits, but the passenger ship berth configuration at Jeju Port have not improved significantly. In this study, the current status of passenger ships at Jeju Port was investigated, and a mooring safety assessment was conducted on car ferries exceeding the design berth capacity of the pier. Risk factors of the target ship were identified through mooring safety assessment. Through the sensitivity analysis of each improvement plan, a plan to improve mooring configuration was proposed and its effect was confirmed. As a result, the in case of Arion Jeju which is berthed at No. 2 pier, improvement plan scenario case 1 to 4 from the operator’s perspective did not secure the mooring safety due to the problem of exceeding maximum traction force with the size of the mooring post. However in case of scenario case 5 of the improvement plan through the additional installation of High Height Bitt, it was analyzed that a load of about 23% or less of the breaking strength of all lines acts on the mooring line and the load of 44% or less of the maximum traction force of the mooring post acts that the mooring safety was evaluated to be secured. The results of this study are expected to be used as reference materials for the establishment of safe passenger ship berth mooring configuration and the development of guidelines for mooring a car ferry.
{"title":"A Study on the Improvement of Mooring Configuration through Mooring Safety Assessment for Passenger Ship Berth","authors":"Daegun Kim, Eun-ji Kang, Ik-Soon Cho","doi":"10.20481/kscdp.2022.9.2.145","DOIUrl":"https://doi.org/10.20481/kscdp.2022.9.2.145","url":null,"abstract":"Most of the domestic car ferries departing from Jeju Port in Korea were replaced through the construction of new ships or the introduction of new used ships starting in 2018 after the Sewol Ferry accident. Amid this trend of ship replacement, the size of passenger ship has also become larger than in the past to increase passenger sales and cargo transportation profits, but the passenger ship berth configuration at Jeju Port have not improved significantly. In this study, the current status of passenger ships at Jeju Port was investigated, and a mooring safety assessment was conducted on car ferries exceeding the design berth capacity of the pier. Risk factors of the target ship were identified through mooring safety assessment. Through the sensitivity analysis of each improvement plan, a plan to improve mooring configuration was proposed and its effect was confirmed. As a result, the in case of Arion Jeju which is berthed at No. 2 pier, improvement plan scenario case 1 to 4 from the operator’s perspective did not secure the mooring safety due to the problem of exceeding maximum traction force with the size of the mooring post. However in case of scenario case 5 of the improvement plan through the additional installation of High Height Bitt, it was analyzed that a load of about 23% or less of the breaking strength of all lines acts on the mooring line and the load of 44% or less of the maximum traction force of the mooring post acts that the mooring safety was evaluated to be secured. The results of this study are expected to be used as reference materials for the establishment of safe passenger ship berth mooring configuration and the development of guidelines for mooring a car ferry.","PeriodicalId":326564,"journal":{"name":"Korea Society of Coastal Disaster Prevention","volume":"2016 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-04-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129931085","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2022-04-30DOI: 10.20481/kscdp.2022.9.2.133
Tae-Gyeong Hwang, Tae-Yoo Kim, S. Choi, Chanhyun Ko, Woo-Dong Lee
The characteristics of a secondary disaster are not well known with respect to the drift-impact by storm surge or tsunami. A numerical analysis for understanding the characteristics of a secondary disaster must be capable of simulating fluid dynamics as well as structural behaviors. In this sense, a fluid-structure interaction analysis is necessary with specialized numerical model such as LS-DYNA. In this study, we numerically simulated the breakaway-drift-impact process of a container due to break waves using LS-DYNA, and additionally examined the applicability of the model. Furthermore, we investigated the validity and effectiveness of an LS-DYNA analysis through the wave pressure comparison of measured values in a hydraulic experiment and the calculated values. In the analysis of drift-impact of a container due to dam-break waves, the drift velocity had a dominant effect, which is in line with previous experiments. In the collision analysis of drifting object due to storm surge/tsunami, the LS-DYNA simulation was proven as an appropriate numerical approach in this study.
{"title":"On Applicability of LS-DYNA for Collision Analysis of Drifting Objects","authors":"Tae-Gyeong Hwang, Tae-Yoo Kim, S. Choi, Chanhyun Ko, Woo-Dong Lee","doi":"10.20481/kscdp.2022.9.2.133","DOIUrl":"https://doi.org/10.20481/kscdp.2022.9.2.133","url":null,"abstract":"The characteristics of a secondary disaster are not well known with respect to the drift-impact by storm surge or tsunami. A numerical analysis for understanding the characteristics of a secondary disaster must be capable of simulating fluid dynamics as well as structural behaviors. In this sense, a fluid-structure interaction analysis is necessary with specialized numerical model such as LS-DYNA. In this study, we numerically simulated the breakaway-drift-impact process of a container due to break waves using LS-DYNA, and additionally examined the applicability of the model. Furthermore, we investigated the validity and effectiveness of an LS-DYNA analysis through the wave pressure comparison of measured values in a hydraulic experiment and the calculated values. In the analysis of drift-impact of a container due to dam-break waves, the drift velocity had a dominant effect, which is in line with previous experiments. In the collision analysis of drifting object due to storm surge/tsunami, the LS-DYNA simulation was proven as an appropriate numerical approach in this study.","PeriodicalId":326564,"journal":{"name":"Korea Society of Coastal Disaster Prevention","volume":"11 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-04-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116866468","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2022-01-30DOI: 10.20481/kscdp.2022.9.1.43
Bong-Soo Son, K. Do
In this study, we simulated storm waves induced by typhoon Maysak and Haishen in the Korean peninsula by using the third-generation numerical wave model SWAN(Simulating WAves Nearshore). We used the sea-surface wind data of KMA(Korea Meteorological Agency)’s operational meteorological model RDAPS(Regional Data Assimilation Prediction System), and JMA(Japan Meteorological Agency)’s weather forecast model JMA-MSM(Meso-Scale Model) as input forcing of the numerical wave model. In addition, the wind field of the tropical cyclone was established with JTWC(Joint Typhoon Warning Center)’s best track data for the storm wave simulation. We used two different source term options, which consider other physics of energy generation by wind and dissipation by whitecapping. Validation of the simulation result was conducted over statistical analysis with the observation data from KMA and KHOA(Korea Hydrographic and Oceanographic Agency)’s buoys. As a result, the whole scenario tended to overestimate significant wave height. The simulation result by using RDAPS as input forcing outperformed the result by using JMA-MSM. It denoted that the performance of a wave model depends on the accuracy of input forcing wind. The wind field by JTWC’s best track data was not suitable compared with the meteorological numerical model. ST6 simulated the wave height higher than Komen’s source term. However, Komen's source term simulated storm waves better than ST6 in this study, and further researches under various conditions are required to evaluate ST6 for the storm waves simulation. In the simulation of wave period parameters, it was hard to estimate the accuracy of the model, and other approaches are necessary for the evaluation.
本文利用第三代数值波浪模式SWAN(simulation waves Nearshore)模拟了台风“梅萨克”和台风“海神”在朝鲜半岛引发的风暴波浪。采用韩国气象厅业务气象模式RDAPS(Regional data Assimilation Prediction System)和日本气象厅天气预报模式JMA- msm (Meso-Scale model)海面风资料作为数值波浪模式的输入强迫。此外，利用JTWC(联合台风预警中心)的最佳路径资料建立了该热带气旋的风场，进行了风暴波模拟。我们使用了两种不同的源项选项，它们考虑了风产生能量的其他物理特性和白浪的耗散。利用韩国气象厅和韩国水文海洋局浮标的观测资料进行统计分析，对模拟结果进行了验证。因此，整个情景往往高估了重要的波高。采用RDAPS作为输入强制的仿真结果优于采用JMA-MSM的仿真结果。说明波浪模型的性能取决于输入强迫风的精度。JTWC最佳路径资料所反映的风场与气象数值模式不太吻合。ST6模拟了高于Komen源项的波高。但在本研究中，Komen的源项对风暴波的模拟效果优于ST6，需要在各种条件下对ST6对风暴波模拟效果的评价进行进一步研究。在波浪周期参数的模拟中，模型的精度难以估计，需要其他方法来评估。
{"title":"Numerical Simulation of Storm Waves during Typhoon Maysak and Haishen in the Korean Peninsula","authors":"Bong-Soo Son, K. Do","doi":"10.20481/kscdp.2022.9.1.43","DOIUrl":"https://doi.org/10.20481/kscdp.2022.9.1.43","url":null,"abstract":"In this study, we simulated storm waves induced by typhoon Maysak and Haishen in the Korean peninsula by using the third-generation numerical wave model SWAN(Simulating WAves Nearshore). We used the sea-surface wind data of KMA(Korea Meteorological Agency)’s operational meteorological model RDAPS(Regional Data Assimilation Prediction System), and JMA(Japan Meteorological Agency)’s weather forecast model JMA-MSM(Meso-Scale Model) as input forcing of the numerical wave model. In addition, the wind field of the tropical cyclone was established with JTWC(Joint Typhoon Warning Center)’s best track data for the storm wave simulation. We used two different source term options, which consider other physics of energy generation by wind and dissipation by whitecapping. Validation of the simulation result was conducted over statistical analysis with the observation data from KMA and KHOA(Korea Hydrographic and Oceanographic Agency)’s buoys. As a result, the whole scenario tended to overestimate significant wave height. The simulation result by using RDAPS as input forcing outperformed the result by using JMA-MSM. It denoted that the performance of a wave model depends on the accuracy of input forcing wind. The wind field by JTWC’s best track data was not suitable compared with the meteorological numerical model. ST6 simulated the wave height higher than Komen’s source term. However, Komen's source term simulated storm waves better than ST6 in this study, and further researches under various conditions are required to evaluate ST6 for the storm waves simulation. In the simulation of wave period parameters, it was hard to estimate the accuracy of the model, and other approaches are necessary for the evaluation.","PeriodicalId":326564,"journal":{"name":"Korea Society of Coastal Disaster Prevention","volume":"217 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-01-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132244749","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2022-01-30DOI: 10.20481/kscdp.2022.9.1.91
Su-Hyun Yang, Seung-Bae Choi, H. Ryu, Kyu-Nam Hwang
In this study, the analysis of sea level change using Lanczos filtering, a filtering method of Fourier transform, was performed. The high frequency(short period) of tide was excluded by low-pass filter of Lanczos filtering, the analysis of sea level change was carried out considering only low frequency(long period). First, all tide data provided by the Korea Hydrographic and Oceanographic Administration(KHOA) were preprocessed to delete the error value, the astronomical tide and the meteorological tide repeated in short period were excluded by Lanczos filtering. The Mean Sea Level(MSL) for each tidal station was calculated using these results, the MSL tended to rise at most point in the Korean coastal zone. And the rate of sea level change, which means annual sea level change(mm/year), was estimated and compared with previous study results. The rate of sea level change was higher than values in past study, this means that future sea level change may be greater than previous expected. The analysis method applied to this study can be effectively used to improve the accuracy of prediction of sea level change.
{"title":"A Study on Analysis Method of Sea Level Change in Korean Coastal Zone","authors":"Su-Hyun Yang, Seung-Bae Choi, H. Ryu, Kyu-Nam Hwang","doi":"10.20481/kscdp.2022.9.1.91","DOIUrl":"https://doi.org/10.20481/kscdp.2022.9.1.91","url":null,"abstract":"In this study, the analysis of sea level change using Lanczos filtering, a filtering method of Fourier transform, was performed. The high frequency(short period) of tide was excluded by low-pass filter of Lanczos filtering, the analysis of sea level change was carried out considering only low frequency(long period). First, all tide data provided by the Korea Hydrographic and Oceanographic Administration(KHOA) were preprocessed to delete the error value, the astronomical tide and the meteorological tide repeated in short period were excluded by Lanczos filtering. The Mean Sea Level(MSL) for each tidal station was calculated using these results, the MSL tended to rise at most point in the Korean coastal zone. And the rate of sea level change, which means annual sea level change(mm/year), was estimated and compared with previous study results. The rate of sea level change was higher than values in past study, this means that future sea level change may be greater than previous expected. The analysis method applied to this study can be effectively used to improve the accuracy of prediction of sea level change.","PeriodicalId":326564,"journal":{"name":"Korea Society of Coastal Disaster Prevention","volume":"35 1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-01-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116596030","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2022-01-30DOI: 10.20481/kscdp.2022.9.1.61
Y. Cho
This study aims to develop a new methodology to generate random waves from a joint distribution of wave amplitude and its associated period. In doing so, the wave spectrum was derived from the joint distribution of wave amplitude and associated period and compared with the Wallops spectrum, which has been most frequently referred to in the literature. Numerical simulation shows that the nonlinearity of random waves makes a significant difference in the wave spectrum. These differences are summarized by a somewhat excessive peak period of the semi-empirical wave spectrum and underestimating wave energy over the high-frequency band. These behavioral characteristics of wave spectrum derived from the joint distribution of wave amplitude and its associated period are conceived to be due to the intrinsic property of the nonlinear random waves. The rationale of this reasoning can be found in the fact that non-negligible amount of wave energy shifts to the relatively short and long period band due to the resonant wave-wave interaction as nonlinearity is getting more pronounced as widely known in the coastal engineering community after studies of Hasselmann(1967) and Phillips(1980) on the developments of wind waves. Among the differences mentioned above, an excessively high peak period can be fully predicted by recalling that the wave period is getting shortened due to the phase difference between the free mode waves among the higher-order harmonic components appearing in random waves due to resonant wave-wave interaction and the resulting destructive interaction.
{"title":"Monte Carlo Simulation of Random Waves at Finite Depth Based on the Joint Distribution of Wave Amplitude and its Associated Period in Nonlinear Random Waves of Finite Bandwidth","authors":"Y. Cho","doi":"10.20481/kscdp.2022.9.1.61","DOIUrl":"https://doi.org/10.20481/kscdp.2022.9.1.61","url":null,"abstract":"This study aims to develop a new methodology to generate random waves from a joint distribution of wave amplitude and its associated period. In doing so, the wave spectrum was derived from the joint distribution of wave amplitude and associated period and compared with the Wallops spectrum, which has been most frequently referred to in the literature. Numerical simulation shows that the nonlinearity of random waves makes a significant difference in the wave spectrum. These differences are summarized by a somewhat excessive peak period of the semi-empirical wave spectrum and underestimating wave energy over the high-frequency band. These behavioral characteristics of wave spectrum derived from the joint distribution of wave amplitude and its associated period are conceived to be due to the intrinsic property of the nonlinear random waves. The rationale of this reasoning can be found in the fact that non-negligible amount of wave energy shifts to the relatively short and long period band due to the resonant wave-wave interaction as nonlinearity is getting more pronounced as widely known in the coastal engineering community after studies of Hasselmann(1967) and Phillips(1980) on the developments of wind waves. Among the differences mentioned above, an excessively high peak period can be fully predicted by recalling that the wave period is getting shortened due to the phase difference between the free mode waves among the higher-order harmonic components appearing in random waves due to resonant wave-wave interaction and the resulting destructive interaction.","PeriodicalId":326564,"journal":{"name":"Korea Society of Coastal Disaster Prevention","volume":"49 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-01-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127472970","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2022-01-30DOI: 10.20481/kscdp.2022.9.1.1
Young-Jae Yoo, Yongho Moon, W. Park
In this study, the appropriateness of structure layout design was reviewed by conducting on empirical study on Namhangjin beach to which the hard defense was applied so that an efficient layout design could be made when the hard defense construction was applied in the future coastal improvement projects. As for the research method, the controlled coastlines was set for the target beach, the evaluation shoreline was calculated for the structure, and the accuracy was reviewed by comparing it with the shoreline survey data after the project. In the case of Namhangjin beach, the feasibility of the coastal improvement project was confirmed by this study, and improvements in the wave height transmission rate ERF calculation formula were confirmed.
{"title":"An Empirical Study on the Setting and Evaluation Method of the Controlled Coastlines according to the Hard Defense of Coastal Improvement Project","authors":"Young-Jae Yoo, Yongho Moon, W. Park","doi":"10.20481/kscdp.2022.9.1.1","DOIUrl":"https://doi.org/10.20481/kscdp.2022.9.1.1","url":null,"abstract":"In this study, the appropriateness of structure layout design was reviewed by conducting on empirical study on Namhangjin beach to which the hard defense was applied so that an efficient layout design could be made when the hard defense construction was applied in the future coastal improvement projects. As for the research method, the controlled coastlines was set for the target beach, the evaluation shoreline was calculated for the structure, and the accuracy was reviewed by comparing it with the shoreline survey data after the project. In the case of Namhangjin beach, the feasibility of the coastal improvement project was confirmed by this study, and improvements in the wave height transmission rate ERF calculation formula were confirmed.","PeriodicalId":326564,"journal":{"name":"Korea Society of Coastal Disaster Prevention","volume":"369 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-01-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123486921","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2022-01-30DOI: 10.20481/kscdp.2022.9.1.23
Yeon-Joong Kim, Joung-Woon Woo, Jong-sung Yoon
Shoreline variations occurring in sea areas are caused by the combined effect of sediment transport due to the inflow and outflow of sediment caused by waves at the left and right boundaries of the sea area and the depth of movement limit. Although many studies have been conducted to understand the characteristics of sediment transport, assessment on valid sediment run-off supplied to the sea area from mountains and rivers in sea areas with river inflow and research on the sediment budget analysis considering the topographical characteristics of South Korean sea areas are insufficient. Therefore, the establishing mitigation measures considering comprehensive viewpoints is necessary to systematically respond to various natural and anthropogenic causes. Moreover, further research related to the setting and analysis of major parameters must be conducted for improving the prediction performance as well as the evaluation system for analyzing the sediment budget, which is a quantitative evaluation index for coastline management optimized for domestic waters. This study aimed to establish a comprehensive analysis system for analyzing the sediment run-off generated in domestic sea areas and develop a shoreline model (In-MPaS model) considering mixed grain sizes for advancing sediment run-off analysis. With the observation data, the parameters necessary for the numerical analysis were set, the sensitivity of the In-MPaS model according to the particle size distribution of the sediment constituting the sea area was evaluated, and the major parameters for improving the prediction performance were analyzed. Consequently, it was found that the prediction performance of the In-MPaS model improved in terms of valid sediment run-off as well as the sediments constituting the sea area (which was assumed to have mixed grain sizes rather than a single grain size(D50). In particular, considering the topographical properties that regulate sediment transport due to the island (Deokbong Mountain) at the foreside of the river mouth bar, the shoreline prediction performance was significantly improved with the application of groins, which exhibit structurally similar performance.
{"title":"Advancements in Shoreline Variation Prediction Considering Mixed Grain Sizes","authors":"Yeon-Joong Kim, Joung-Woon Woo, Jong-sung Yoon","doi":"10.20481/kscdp.2022.9.1.23","DOIUrl":"https://doi.org/10.20481/kscdp.2022.9.1.23","url":null,"abstract":"Shoreline variations occurring in sea areas are caused by the combined effect of sediment transport due to the inflow and outflow of sediment caused by waves at the left and right boundaries of the sea area and the depth of movement limit. Although many studies have been conducted to understand the characteristics of sediment transport, assessment on valid sediment run-off supplied to the sea area from mountains and rivers in sea areas with river inflow and research on the sediment budget analysis considering the topographical characteristics of South Korean sea areas are insufficient. Therefore, the establishing mitigation measures considering comprehensive viewpoints is necessary to systematically respond to various natural and anthropogenic causes. Moreover, further research related to the setting and analysis of major parameters must be conducted for improving the prediction performance as well as the evaluation system for analyzing the sediment budget, which is a quantitative evaluation index for coastline management optimized for domestic waters. This study aimed to establish a comprehensive analysis system for analyzing the sediment run-off generated in domestic sea areas and develop a shoreline model (In-MPaS model) considering mixed grain sizes for advancing sediment run-off analysis. With the observation data, the parameters necessary for the numerical analysis were set, the sensitivity of the In-MPaS model according to the particle size distribution of the sediment constituting the sea area was evaluated, and the major parameters for improving the prediction performance were analyzed. Consequently, it was found that the prediction performance of the In-MPaS model improved in terms of valid sediment run-off as well as the sediments constituting the sea area (which was assumed to have mixed grain sizes rather than a single grain size(D50). In particular, considering the topographical properties that regulate sediment transport due to the island (Deokbong Mountain) at the foreside of the river mouth bar, the shoreline prediction performance was significantly improved with the application of groins, which exhibit structurally similar performance.","PeriodicalId":326564,"journal":{"name":"Korea Society of Coastal Disaster Prevention","volume":"64 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-01-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127623218","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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