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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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Korean Society of Coastal and Ocean Engineers
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Volume & Issues
Volume 25, Issue 6 - Dec 2013
Volume 25, Issue 5 - Oct 2013
Volume 25, Issue 4 - Aug 2013
Volume 25, Issue 3 - Jun 2013
Volume 25, Issue 2 - Apr 2013
Volume 25, Issue 1 - Feb 2013
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Characteristics of Mass Transport Depending on the Feature of Tidal Creek at Han River Estuary, Gyeong-gi Bay, South Korea
Kim, Minha ; Woo, Seung-Buhm ;
Journal of Korean Society of Coastal and Ocean Engineers, volume 25, issue 2, 2013, Pages 41~51
DOI : 10.9765/KSCOE.2013.25.2.41
The tidal creek dependent mass transport characteristic in Gyeong-Gi Bay (west coast of Korea) was studied using field measured data and numerical model. Gyeong-Gi Bay consists of 3 main tidal channels and contains a well-developed vast tidal flat. This region is famous for its large tidal difference and strong current. We aim to study the effect of tidal creek in the tidal flat on the mass exchange between the estuary and the ocean. For numerical application, the application of unstructured grid feature is essential, since the tidal creek has complicated shape and form. For this purpose, the FVCOM is applied to the study area and simulation is performed for 2 different cases. In case A, geographic characteristics of the tidal creek is ignored in the numerical grid and in case B, the tidal creek are constructed using unstructured grid. And these 2 cases are compared with the field measured cross-channel mass transport data. The cross-channel mass transport at the Yeomha waterway mouth and Incheon harbor was measured in June, 9~10 (Spring tide) and 17~18 (Neap tide), 2009. CTD casting and ADCP cross-channel transect was conducted 13 times in one tidal cycle. The observation data analysis results showed that mass transport has characteristic of the ebb dominance Line 1 (Yeomha waterway mouth), on the other hand, a flood dominant characteristic is shown in Line 2 (Incheon harbor front). By comparing the numerical model (case A & B) with observation data, we found that the case B results show much better agreement with measurement data than case A. It is showed that the geographic feature of tidal creek should be considered in grid design of numerical model in order to understand the mass transport characteristics over large tidal flat area.
Development of Stochastic Markov Process Model for Maintenance of Armor Units of Rubble-Mound Breakwaters
Lee, Cheol-Eung ;
Journal of Korean Society of Coastal and Ocean Engineers, volume 25, issue 2, 2013, Pages 52~62
DOI : 10.9765/KSCOE.2013.25.2.52
A stochastic Markov process (MP) model has been developed for evaluating the probability of failure of the armor unit of rubble-mound breakwaters as a function of time. The mathematical MP model could have been formulated by combining the counting process or renewal process (CP/RP) on the load occurrences with the damage process (DP) on the cumulative damage events, and applied to the armor units of rubble-mound breakwaters. Transition probabilities have been estimated by Monte-Carlo simulation (MCS) technique with the definition of damage level of armor units, and very well satisfies some conditions constrained in the probabilistic and physical views. The probabilities of failure have been also compared and investigated in process of time which have been calculated according to the variations of return period and safety factor being the important variables related to design of armor units of rubble-mound breakwater. In particular, it can be quantitatively found how the prior damage levels can effect on the sequent probabilities of failure. Finally, two types of methodology have been in this study proposed to evaluate straightforwardly the repair times which are indispensable to the maintenance of armor units of rubble-mound breakwaters and shown several simulation results including the cost analyses.
Numerical Hydrodynamic Modeling Incorporating the Flow through Permeable Sea-Wall
Bang, Ki-Young ; Park, Sung Jin ; Kim, Sun Ou ; Cho, Chang Woo ; Kim, Tae In ; Song, Yong Sik ; Woo, Seung-Buhm ;
Journal of Korean Society of Coastal and Ocean Engineers, volume 25, issue 2, 2013, Pages 63~75
DOI : 10.9765/KSCOE.2013.25.2.63
The Inner Port Phase 2 area of the Pyeongtaek-Dangjin Port is enclosed by a total of three permeable sea-walls, and the disposal site to the east of the Inner Port Phase 2 is also enclosed by two permeable sea-walls. The maximum tidal range measured in the Inner Port Phase 2 and in the disposal site in May 2010 is 4.70 and 2.32 m, respectively. It reaches up to 54 and 27%, respectively of 8.74 m measured simultaneously in the exterior. Regression formulas between the difference of hydraulic head and the rate of interior water volume change, are induced. A three-dimensional numerical hydrodynamic model for the Asan Bay is constructed incorporating a module to compute water discharge through the permeable sea-walls at each computation time step by employing the formulas. Hydrodynamics for the period from 13th to 27th May, 2010 is simulated by driving forces of real-time reconstructed tide with major five constituents(
) and freshwater discharges from Asan, Sapkyo, Namyang and Seokmoon Sea dikes. The skill scores of modeled mean high waters, mean sea levels and mean low waters are excellent to be 96 to 100% in the interior of permeable sea-walls. Compared with the results of simulation to obstruct the flow through the permeable sea-walls, the maximum current speed increases by 0.05 to 0.10 m/s along the main channel and by 0.1 to 0.2 m/s locally in the exterior of the Outer Sea-wall of Inner Port. The maximum bottom shear stress is also intensified by 0.1 to 0.4
in the main channel and by more than 0.4
locally around the arched Outer Sea-wall. The module developed to compute the flow through impermeable seawalls can be practically applied to simulate and predict the advection and dispersion of materials, the erosion or deposion of sediments, and the local scouring around coastal structures where large-scale permeable sea-walls are maintained.
Numerical Modeling of Sediment Transport during the 2011 Summer Flood in the Youngsan River Estuary, Korea
Bang, Ki-Young ; Kim, Tae In ; Song, Yong Sik ; Lee, Jung Hyun ; Kim, Shin Woong ; Cho, Jae-Gab ; Kim, Jong Wook ; Woo, Seung Buhm ; Oh, Jae Kyung ;
Journal of Korean Society of Coastal and Ocean Engineers, volume 25, issue 2, 2013, Pages 76~93
DOI : 10.9765/KSCOE.2013.25.2.76
The hydrodynamics in the Youngsan River Estuary has changed due to coastal developments such as the estuary dam and two tidal barriers. As the freshwater discharge is artificially controlled, the circulation pattern is different from those of natural estuaries and the river-born sediment supply is restricted. 3D numerical modeling system EFDC was applied to investigate the sediment transport pattern and budget in summer with river floods. The real-time driving forces and the fluvial sediment discharges from the watershed modeling were assigned for the simulation period. The size classes of sand, silt and clay were adopted based on the grain-size distribution of bottom sediments. The modeling results were calibrated and validated with the observed tides, tidal currents and suspended sediment concentrations. The suspended sediments are transported to the offshore at surface layer, whereas upstream toward the dam at mid- and bottom layers in August 2011. The characteristic estuarine circulation induced by the freshwater discharge from the dam, causes the deposition of silt-sized sediments on the whole and the sustained suspension of clay-sized sediments.
Numerical Modeling on the Change in Discharge Performance of the Sluice for Tidal Power Plant According to the Apron Shape
Oh, Sang-Ho ; Han, In-Suk ; Kim, Gunwoo ; Jeong, Weon-Mu ;
Journal of Korean Society of Coastal and Ocean Engineers, volume 25, issue 2, 2013, Pages 94~102
DOI : 10.9765/KSCOE.2013.25.2.94
In this study, numerical modeling was performed to investigate influence of the apron shape on the discharge performance of the sluice for tidal power plant. The numerical modeling was carried out for comparison of the difference in the discharge coefficient when the apron width, slope, and the length of the horizontal section were different, without considering change in the shape of the sluice caisson itself. The modeling result showed that significant discrepancy in terms of the overall discharge performance appeared according to the apron geometry. In order to achieve maximum discharge performance of the sluice caisson, it is desirable to make the design by putting a space equivalent to the width of the sluice caisson on its both sides, by making the apron slope be 1:5, and by keeping length of the horizontal section to be 50 m that is corresponding to the streamwise length of the sluice caisson.
Spatial and Temporal Variability of Residual Current and Salinity according to Freshwater Discharge in Yeoungsan River Estuary
Kim, Jong-Wook ; Yoon, Byung Il ; Song, Jin Il ; Lim, Chae Wook ; Woo, Seung-Buhm ;
Journal of Korean Society of Coastal and Ocean Engineers, volume 25, issue 2, 2013, Pages 103~111
DOI : 10.9765/KSCOE.2013.25.2.103
In this study, field measurements were conducted in the section about 7 km from sea dike to westward. The observations of along channel current were carried out, and water temperature and salinity were measured simultaneously at 10 stations during one tidal cycle, and sampling interval is 1 hour. The maximum ebb current is about 1.5 m/s at the surface layer but flood current is 0.4 m/s at the bottom layer during discharge period. Residual current during river discharge shows two layer structures which is typical characteristic of the estuary system. On the other hand, residual current during a period with no discharge has shown multi-layer structure different from general estuarine systems. The distribution of high salinity can be seen at the bottom layer as the effect of discharge does not reach down to the bottom layer during discharge. As a result, freshwater is not effected at the bottom layer during observation, and mixing of surface layer to bottom layer is reduced by stratification.
Estimation of Ultimate Bearing Capacity of Gravel Compaction Piles Using Nonlinear Regression Analysis
Park, Joon Mo ; Han, Yong Bae ; Jang, Yeon Soo ;
Journal of Korean Society of Coastal and Ocean Engineers, volume 25, issue 2, 2013, Pages 112~121
DOI : 10.9765/KSCOE.2013.25.2.112
The calibration of resistance factor in reliability theory for limit state design of gravel compaction piles (GCP) requires a reliable estimate of ultimate bearing capacity. The static load test is commonly used in geotechnical engineering practice to predict the ultimate bearing capacity. Many graphical methods are specified in the design standard to define the ultimate bearing capacity based on the load-settlement curve. However, it has some disadvantages to ensure reliability to obtain an uniform ultimate load depend on engineering judgement. In this study, a well-fitting nonlinear regression model is proposed to estimate the ultimate bearing capacity, for which a nonlinear regression analysis is applied to estimate the ultimate bearing capacity of GCP and the results are compared with those calculated using previous graphical method. Affect the resistance factor of the estimate method were analyzed. To provide a database in the development of limit state design, the load test conditions for predicting the ultimate bearing capacity from static load test are examined.