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REFERENCE LINKING PLATFORM OF KOREA S&T JOURNALS
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Journal of Korean Society of Coastal and Ocean Engineers
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Journal DOI :
Korean Society of Coastal and Ocean Engineers
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Volume & Issues
Volume 26, Issue 6 - Dec 2014
Volume 26, Issue 5 - Oct 2014
Volume 26, Issue 4 - Aug 2014
Volume 26, Issue 3 - Jun 2014
Volume 26, Issue 2 - Apr 2014
Volume 26, Issue 1 - Feb 2014
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Comparative Study of Design Methods for Sliding of Perforated-wall Caisson Breakwater
Kim, Nam-Hoon ; Suh, Kyung-Duck ;
Journal of Korean Society of Coastal and Ocean Engineers, volume 26, issue 5, 2014, Pages 267~277
DOI : 10.9765/KSCOE.2014.26.5.267
The conventional performance-based design method for the solid-wall caisson breakwater has been extended and applied to the perforated-wall caisson. The mathematical model to calculate the sliding distance of a perforated-wall caisson is verified against hydraulic experimental data. The developed performance-based design method is then compared with the conventional deterministic method in different water depths. Both the expected sliding distance and the exceedance percentage of total sliding distance during the structure lifetime decrease with decreasing water depth outside the surf zone, but they increase with decreasing water depth inside the surf zone. The performance-based design method is either more economical or less economical than the deterministic method depending on which design criterion is used. If the criterion for the ultimate limit state is used, the former method is less economical than the latter outside the surf zone, whereas the two methods are equally economical inside the surf zone. However, if the breakwater is designed to satisfy the criterion for the repairable limit state, the former method is more economical than the latter in all water depths.
Estimation on the Distribution Function for Coastal Air Temperature Data in Korean Coasts
Jeong, Shin Taek ; Cho, Hongyeon ; Ko, Dong Hui ; Hwang, Jae Dong ;
Journal of Korean Society of Coastal and Ocean Engineers, volume 26, issue 5, 2014, Pages 278~284
DOI : 10.9765/KSCOE.2014.26.5.278
Water temperature due to climate change can be estimated using the air temperature because the air and water temperatures are closely related and the water temperatures have been widely used as the indicators of the environmental and ecological changes. It is highly necessary to estimate the frequency distribution of the air and water temperatures, for the climate change derives the change of the coastal water temperatures. In this study, the distribution function of the air temperatures is estimated by using the long-term coastal air temperature data sets in Korea. The candidate distribution function is the bi-modal distribution function used in the previous studies, such as Cho et al.(2003) on tidal elevation data and Jeong et al.(2013) on the coastal water temperature data. The parameters of the function are optimally estimated based on the least square method. It shows that the optimal parameters are highly correlated to the basic statistical informations, such as mean, standard deviation, and skewness coefficient. The RMS error of the parameter estimation using statistical information ranges is about 5 %. In addition, the bimodal distribution fits good to the overall frequency pattern of the air temperature. However, it can be regarded as the limitations that the distribution shows some mismatch with the rapid decreasing pattern in the high-temperature region and the some small peaks.
Efficient Outlier Detection of the Water Temperature Monitoring Data
Cho, Hongyeon ; Jeong, Shin Taek ; Ko, Dong Hui ; Son, Kyeong-Pyo ;
Journal of Korean Society of Coastal and Ocean Engineers, volume 26, issue 5, 2014, Pages 285~291
DOI : 10.9765/KSCOE.2014.26.5.285
The statistical information of the coastal water temperature monitoring data can be biased because of outliers and missing intervals. Though a number of outlier detection methods have been developed, their applications are very limited to the in-situ monitoring data because of the assumptions of the a prior information of the outliers and no-missing condition, and the excessive computational time for some methods. In this study, the practical robust method is developed that can be efficiently and effectively detect the outliers in case of the big-data. This model is composed of these two parts, one part is the construction part of the approximate components of the monitoring data using the robust smoothing and data re-sampling method, and the other part is the main iterative outlier detection part using the detailed components of the data estimated by the approximate components. This model is tested using the two-years 5-minute interval water temperature data in Lake Saemangeum. It can be estimated that the outlier proportion of the data is about 1.6-3.7%. It shows that most of the outliers in the data are detected and removed with satisfaction by the model. In order to effectively detect and remove the outliers, the outlier detection using the long-span smoothing should be applied earlier than that using the short-span smoothing.
Development of Storm Sewer Numerical Model for Simulation of Coastal Urban Inundation due to Storm Surge and Rainfall
Yoon, Sung Bum ; Lee, Jaehwang ; Kim, Gun Hyeong ; Song, Ji Hoon ;
Journal of Korean Society of Coastal and Ocean Engineers, volume 26, issue 5, 2014, Pages 292~299
DOI : 10.9765/KSCOE.2014.26.5.292
Since most of the researches on the coastal inundation due to typhoons have considered only storm surges, an additional inundation due to rainfall has been neglected. In general, typhoons are natural disasters being accompanied by the rainfall. Thus, it is essential to consider the effect of rainfall in the numerical simulation of coastal inundation due to storm surges. Because the rainwater is discharged to the sea through the storm sewer system, it should be included in the numerical simulation of storm surges to obtain reasonable results. In this study an algorithm that can deal with the effects of rainfall and sewer system is developed and combined with a conventional storm surge numerical model. To test the present numerical model various numerical simulations are conducted using the simplified topography for the cases including the inundation due to rainfall, the drainage of rainwater, the backflow of sea water, and the increase of sea water level due to drainage of rainwater. As a result, it is confirmed that the basic performance of the present model is satisfactory for various flow situations.
Analytical Method of Partial Standing Wave-Induced Seabed Response in Finite Soil Thickness under Arbitrary Reflection
Lee, Kwang-Ho ; Kim, Do-Sam ; Kim, Kyu-Han ; Kim, Dong-Wook ; Shin, Bum-Shick ;
Journal of Korean Society of Coastal and Ocean Engineers, volume 26, issue 5, 2014, Pages 300~313
DOI : 10.9765/KSCOE.2014.26.5.300
Most analytical solutions for wave-induced soil response have been mainly developed to investigate the influence of the progressive and standing waves on the seabed response in an infinite seabed. This paper presents a new analytical solution to the governing equations considering the wave-induced soil response for the partial standing wave fields with arbitrary reflectivity in a porous seabed of finite thickness, using the effective stress based on Biot's theory (Biot, 1941) and elastic foundation coupled with linear wave theory. The newly developed solution for wave-seabed interaction in seabed of finite depth has wide applicability as an analytical solutions because it can be easily extended to the previous analytical solutions by varying water depth and reflection ratio. For more realistic wave field, the partial standing waves caused by the breakwaters with arbitrary reflectivity are considered. The analytical solutions was verified by comparing with the previous results for a seabed of infinite thickness under the two-dimensional progressive and standing wave fields derived by Yamamoto et al.(1978) and Tsai & Lee(1994). Based on the analytical solutions derived in this study, the influence of water depth and wave period on the characteristics of the seabed response for the progressive, standing and partial standing wave fields in a seabed of finite thickness were carefully examined. The analytical solution shows that the soil response (including pore pressure, shear stress, horizontal and vertical effective stresses) for a seabed of finite thickness is quite different in an infinite seabed. In particular, this study also found that the wave-induced seabed response under the partial wave conditions was reduced compared with the standing wave fields, and depends on the reflection coefficient.
Analysis of Generation and Amplification Mechanism of Abnormal Waves Occurred along the West Coast of Korea
Yoon, Sung Bum ; Shin, Choong Hun ; Bae, Jae Seok ;
Journal of Korean Society of Coastal and Ocean Engineers, volume 26, issue 5, 2014, Pages 314~326
DOI : 10.9765/KSCOE.2014.26.5.314
On 31 March 2007, the abnormal wave occurred along the western coast of Korea. In order to investigate the generation mechanism of abnormal waves and to understand the amplification process of the abnormal waves, the observed data were analyzed and one-dimensional numerical model experiments were performed by using both the linear shallow water equation and the linear Boussinesq equation models. Various types of pressure jump for the abnormal waves previously proposed by other researchers were reviewed. As a result, it was not possible to reproduce the abnormal waves from the previously proposed pressure jumps. In this study, we proposed a new form of pressure jump, and numerical simulations were performed in order to check the validity of the proposed pressure jump. The numerical results showed that the calculated period of abnormal waves and the maximum water elevations agreed reasonably well with those of the observations.
A Laboratory Study for Settling Velocities of Cohesive Sediments Entering in Semi-closed Channel
Kim, Dong-Ho ; Yang, Su-Hyun ; Hwang, Kyu-Nam ;
Journal of Korean Society of Coastal and Ocean Engineers, volume 26, issue 5, 2014, Pages 327~334
DOI : 10.9765/KSCOE.2014.26.5.327
This study aims to estimate settling velocity (
) for cohesive sediments from water bodies (Incheon Coast, Kulpo Stream and Han River) mainly connected to the Kyeongin Ara-waterway through the laboratory settling experiments. Results of settling tests for these sediments show that
values for sediments are quite different each other:
values of Kulpo Stream sediments (0.01 <
< 3.07 mm/s) are quite similar with those of Han River sediments (0.01 <
< 2.97 mm/s) over the whole range of suspension concentration C (0.1 < C < 90 g/ L), while they are quite different with those for Incheon Coast sediments (0.01 <
<0.92 mm/s). Qualitative analyses on test results for physico- chemical properties of sediments and waters with respect to settling velocities show that these differences in settling velocities are mainly due to the salinity difference in the water.
Comparison of Maximum Horizontal Wave Force Acting on Perforated Caisson Breakwater with Single and Double Chamber
Oh, Sang-Ho ; Ji, Chang-Hwan ; Oh, Young Min ; Jang, Se-Chul ; Lee, Dal Soo ;
Journal of Korean Society of Coastal and Ocean Engineers, volume 26, issue 5, 2014, Pages 335~341
DOI : 10.9765/KSCOE.2014.26.5.335
Physical experiments were carried out to measure the wave force on the vertical walls of perforated breakwater considering several phases of a wave acting on the breakwater. The maximum horizontal wave force acting on each vertical wall was compared between single and double chamber caisson breakwater. The experimental data in this study showed that the total horizontal wave force for double chamber caisson was 9.6% smaller on average than that for single chamber caisson when the total chamber width was the same for both caissons. Such reduction of the wave force is due to the dissipation of wave energy at the porous middle wall, which is located between the porous front wall and non-porous rear wall.