• Journal of Coastal Disaster Prevention
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• v.4 no.spc
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• pp.245-253
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• 2017

In this study, surface currents measured by small lagrangian GPS drifters (Aquadrifter) in Anmok coastal waters were analysed to account for the variability of nearshore surface current and wave-induced current to understand sediment transport mechanism near the crescentic bars in the surf-zone and near Kangneung breakwater and submerged breakwater in Anmok. The 8 times lagrangian drifter experiments were conducted mostly during in 2nd, 3rd, 4th intensive measurements in winter, summer, and spring seasons with long-term wave observation at the station W1. The analysed surface currents near the breakwaters in Anmok show that wave-induced currents at the middle of the submerged breakwater were separated and flowed toward the shoreline but offshore currents were dominant through the channels between the breakwaters. The longshore currents near the shoreline were flowed to the northwest (southeast) depending on the incoming waves from ENE (NNE). The surface nearshore offshore currents were generated mostly by waves and winds in case of high and low wave energy environments. Using the small-size lagrangian surface drifter experiments, we successfully measured longshore and offshore wave-induced currents in the surf-zone and near submerged breakwater close to Kangneung breakwater. The drifter experiment results show the availability of direct observation of nearshore surface currents to understand the mechanism of sediment transport analysing observed wave-induced current and ebb-current in the surf-zone generated by incoming waves and local winds.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.14 no.2
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• pp.151-160
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• 2002

A modeling system for three-dimensional flow (FEMOS) has been developed and applied to simulate the tidal currents of Asan Bay. The system can consider tidal flats changing with time and uses a finite element method that can adapt coastline change effectively. The simulation results for Asan Bay with large tidal flats, shallow water depth and high tidal range showed good agreements with the observed currents of long-term variations at the medium layer and short-term variations of vertical profiles. Based on the simulated tidal currents, the horizontal distributions of bottom shear stress were calculated and showed close relation with the change of bottom topography. The system can be used widely to study coastal circulation in the coastal region with complex geography.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.4 no.4
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• pp.231-242
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• 1992

This study uses a numerical model to investigate the circulation patterns of the tidal and wind driven current components. The model is vertically averaged 2-D transient using explicit nume-rical scheme, based on equation of motion and continuity. forced by water elevation at open boundaries and wind stress. The model domain extends from 35$^{\circ}$N to 36$^{\circ}$40'N lat., and 125$^{\circ}$E to 126$^{\circ}$40'E long. with x, y grid spacing of 5 km. The model reproduces the tide and tidal currents by 4 major constituents successfully with more than 90% accuracy when compared to two offshore tidal records and currents at one offshore measurements for 22 days. Responses of coastal waters to six schematic wind events are analyzed in terms of current distribution patterns and local features. Regardless of wind directions. strong coastal currents were produced. Bottom topography plays a critical role in producing a local eddy Held whose center is located offshore Pu An with its major radius of 40 km.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.13 no.1
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• pp.46-55
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• 2001

An approach using the nonlinear wave model in predicting wave-induced currents is presented. The model results were compared with those of the conventional model using phase-averaged radiation stress, and in addition with experimental data captured by a PIV system. As a result of comparison of wave-induced currents generated behind the surface-piercing breakwater and submerged breakwater, eddy patterns appeared to be similar each other but in general numerical solutions of both models were underestimated.

• Journal of the Korean Society for Marine Environment & Energy
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• v.1 no.1
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• pp.93-101
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• 1998

Numerical models have been widely used to understand the structure of coastal currents and the transport mechanisms in regard to the fate of pollutants. This study focuses on the development of a three-dimensional model of coastal circulation and mass transport. The model was used to calculate coastal currents and temperature distributions of the thermal plume discharged from a power plant. The model results were compared with field-observed data. They showed the relatively good agreements with the data. The model can be used to estimate the currents and its mass transport in coastal waters.

• International Journal of Naval Architecture and Ocean Engineering
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• v.3 no.3
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• pp.216-224
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• 2011

In This study develops a quasi-three dimensional numerical model of wave driven coastal currents with accounting the effects of the wave-current interaction and the surface rollers. In the wave model, the current effects on wave breaking and energy dissipation are taken into account as well as the wave diffraction effect. The surface roller associated with wave breaking was modeled based on a modification of the equations by Dally and Brown (1995) and Larson and Kraus (2002). Furthermore, the quasi-three dimensional model, which based on Navier-Stokes equations, was modified in association with the surface roller effect, and solved using frictional step method. The model was validated by data sets obtained during experiments on the Large Scale Sediment Transport Facility (LSTF) basin and the Hazaki Oceanographical Research Station (HORS). Then, a model test against detached breakwater was carried out to investigate the performance of the model around coastal structures. Finally, the model was applied to Akasaki port to verify the hydrodynamics around coastal structures. Good agreements between computations and measurements were obtained with regard to the cross-shore variation in waves and currents in nearshore and surf zone.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.5 no.4
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• pp.414-426
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• 1993

A description is given of the recent techniques employed for the measurement of currents in the East China Sea continental shell The variability of the currents in the region is briefly discussed as it affects the measurement Data sources have been collated to develop an inventory of current observations in the shelf seas around Korea.

• Proceedings of the Korean Society of Coastal and Ocean Engineers Conference
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• 2000.09a
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• pp.140-148
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• 2000

The nearshore currents are required for the preservation of coastal areas and the more pressing environmental problems since they cause sediments to be in suspension and transport the sediments into tranquil regions. Numerical models are often used to calculate current patterns formed around man-made or naturally caused changes around the coastal area. (omitted)

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.27 no.4
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• pp.238-245
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• 2015

Recently, Choi et al.(2015) showed that a numerical simulation of the SandyDuck experiment under a directional random wave environment agreed well with the experimental data including the wave height distribution of the random waves, the well-developed longshore current and its energetic fluctuation. Based on the Boussinesq modeling, this study investigates the effect of the alongshore variations, which are induced by not only the field topography but also the phase interaction of multidirectional random waves in the surf zone wave field, on the rip currents. As a result, transient rip currents as well as topographical rip currents cause the complicated surfzone circulation and mixing process due to their interactions in a multi-directional random wave condition while the topographical rip currents are dominant in a monochromatic wave condition.

• Journal of the Korean Society of Marine Environment & Safety
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• v.18 no.4
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• pp.295-307
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• 2012

In order to understand the flow properties of the South Sea of Korea, tidal currents, wind-driven currents, density-driven currents and residual flows were investigated by using 3-dimensional numerical model(POM). In offshore regions, tide-induced residual current tends to flow eastward during the spring tide and westward during the neap tide. Total residual flow is irregular due to the bottom topography in the coastal area. The density-driven currents in the coastal area showed to be relatively weak, with little seasonal differences. The special tendency was apparent in the open sea. That is, the flow in the offshore regions showed results similar to that of the Tsushima current. The wind-driven currents in the coastal area showed to be much stronger than in offshore regions. Vertically, the flow of the surface layer was much stronger than that of the bottom layer. Through these results, material transport and diffusion in the south coast, as a basis for predicting the spread of use is expected to be available.