• Journal of Korean Society of Coastal and Ocean Engineers
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• v.5 no.2
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• pp.99-106
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• 1993

A two-dimensional numerical analysis is performed for the simulation of intertidal-flat and analysis of hydraulic characteristics during seadike construction in Sae-Man-Keum tidal basin. The shallow water equations are selected as a mathematical model and the Leendertse's ADI scheme is used as the corresponding numerical model. The simulated results of tide and current by the present model agree welt with the experimenta1 results by the hydraulic Lab. or ADC (1989). In the application of the model, the possibility of rapidly varied flow analysis and the introduction of turbulence model required for more accurate hydraulic calculation at closing gap are described. The successive simulation of flooding/drying effects by a modification of the method by Stelling et al. (1986) can easily be used for the intertidal-flat analysis during tidal reclamation.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.12 no.2
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• pp.81-86
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• 2000

For on-shore structures, dynamic analysis becomes increasingly important as the water depth increases and the structural configuration becoines slenderer. In this study, an estimation method for equivalent three dimensional (30) hydrodynamic coefficients is introduced as a part of beam permutation technique development. The beam pemlUtation technique is being developed for obtaining an equivalent beam to a frame structure in order to reduce the degrees of freedom and thus the analysis time significantly. Two 3D structures are used in order to verify the obtained equivalent 3D hydrodynamic coefficients. Two commercial softwares, ANSYS and SACS, are used for the verification. The results of the present analysis are found to be satisfactory in comparison with those by the two softwares.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.23 no.5
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• pp.345-357
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• 2011

Recently, as part of diversifying energy sources and earth environmental issues, technology development of new renewable energy using wave energy is actively promoted and commercialized around Europe and Japan etc. In particular, OWC(Oscillating Water Column) wave power generation system using air flow induced by vertical movement of the water surface by waves in an air-chamber within caisson is known as the most efficient wave energy absorption device and therefore, is one of the wave power generation apparatus the closest to commercialization. This study examines air flow velocity, which operates turbine(Wells turbine) directly in oscillating water column type wave power generation structure from two-and three-dimensional numerical experiments and discusses optimal shape of oscillating water column type wave power generation structure by estimating the maximum flow rate of air according to change in shape. The three-dimensional numerical wave flume was applied in interpretation for this study which is the model for the immiscible two-phase flow based on the Navier-Stokes Equation. From this, it turned out that size of optimal shape appears differently according to the incident wave period and air flow is maximized at the period where minimum reflection ratio occurs.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.18 no.1
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• pp.43-52
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• 2006

Numerical model tests are done in order to evaluate impact zone of low salinity water on outer region of the developing Saemankeum reservoir. Also saline mixing processes are investigated f3r the inner reservoir with consideration of Mankyoung and Donjin riverine flood discharges when sea water is passing freely through gate. In these analyses 2-d ADCIRC, 3-d TIDED3D and CE-QUAL-ICM models are used. Through models tests, it is found that inner reservoir mixing process caused by inflow of outer sea water occurs gradually. It takes at least one month for complete mixing on Mankyoung part and 6 month on Dongjin part of the reservoir. When Sinsi or Garyeok gates are opened to control inner reservoir level, discharging velocities decrease exponentially from the gates, but show very strong currents of 0.5m/sec to the 10Km region apart. These results imply that hydrodynamic circulation and ecosystem of frontal region of the Saemankeum dike might be affected in amount by gate operations, since low saline inner waters are discharged periodically at ebb tide according to tidal level.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.23 no.5
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• pp.335-344
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• 2011

A curvilinear non-hydrostatic free surface model is developed to investigate nonlinear wave interactions in a circular channel. The proposed model solves the unsteady Navier-Stokes equations in a three-dimensional domain with a pressure correction method, which is one of fractional step methods. A hybrid staggered-grid layout in the vertical direction is implemented, which renders relatively simple resulting pressure equation as well as free surface closure. Numerical accuracy with respect to wave nonlinearity is tested against the fifth-order Stokes solution in a two-dimensional numerical wave tank. Numerical applications center on the evolution of nonlinear waves including diffraction and reflection affected by the curvature of side wall in a circular channel comparing with linear waves. Except for a highly nonlinear bichrmatic wave, the model's results are in good agreement with superimposed analytical solution that neglects nonlinear effects. Through the numerical simulation of the highly nonlinear bichramatic wave, the model shows its capability to investigate the evolution of nonlinear wave groups in a circular channel.

• Proceedings of the Korea Water Resources Association Conference
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• 2022.05a
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• pp.2-2
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• 2022

연안지역은 강우, 조위, 월파 등 다양한 재해 요소에 의해 침수될 수 있다. 또한, 이러한 재해 요소는 동시에 발생하여 큰 침수 피해를 유발하기도 한다. 하지만 각각의 재해 요소를 대상으로 하는 기술 분야가 상이하기 때문에 물리 모형 기반의 과학적 방법으로 복합적인 재해 요소를 고려한 침수 분석에 관한 연구는 제약되었다. 이 연구는 강우-유출 및 2차원 지표면 흐름 해석의 수공학적 분석 기술과 조석, 파랑, 월파 등의 해양공학적 기술을 연계하여 연안지역에 대한 복합 외력을 고려한 침수 분석 기술을 제시하는데 목적이 있다. 우선, 먼 바다로부터 예상되는 파랑, 조위 분석에는 ADCIRC와 UnSWAN 모형을 연계한 ADCSWAN이 사용되었다. 연안 주변의 복잡한 흐름 해석과 해안 구조물을 범람하여 발생하는 월파량 산정에는 FLOW-3D 모형을 이용하였다. 그리고 강우-유출 분석과 바다의 조위 및 월파량을 고려할 수 있을 뿐만 아니라 2차원 지표면 침수 해석이 가능한 XP-SWMM을 이용하여 연안지역의 침수 모의를 수행하였다. 모형 간 연계에 의한침수 해석의 적절성을 검토하기 위해 2016년 10월의 태풍 차바 시 대대적인 침수가 발생한 부산 마린시티 지역에 대하여 적용하였다. 침수 모의 결과는 당시의 현장 사진, 침수흔적도와 비교하여 검토되었고, 실제 침수 현상과 유사한 결과가 도출되었다. 이 연구는 연안지역의 복합적인 재해요인에 대한 침수 해석에 수문 분야와 해양공학 분야의 기술 연계를 통해 실제 현상의 재현성을 높인 것에 의의가 있다. 또한, 이 연구에서 제시한 해석 방법은 다양한 연안지역의 침수 원인 분석과 적절한 재해 방지 대책 수립에 활용될 수 있을 것으로 판단된다.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.22 no.1
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• pp.58-66
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• 2010

In this paper, we have constructed high-resolution topographical map of macro-tidal Malipo beach through integration of terrestrial LiDAR measurement and MBES survey data at inter-tidal zone. To acquire the enough information of inter-tidal zone, we have done terrestrial LiDAR measurement mounted on the roof of vehicle with DGPS through go-stop-scan method at the ebb tide and MBES depth surveying with tide gauge and eye staff measurement for tide correction and MSL calculation at the high tide all together. To integrate two kinds of data, we have unified the vertical coordination standard to Incheon MSL. The mean error of overlapped inter-tidal zone is about 2~6 cm. To verify the accuracy of terrestrial LiDAR, RTK-DGPS measurement have done simultaneously and the difference of Z value RMSE is about 4~7 cm. The resolution of Malipo topographical map is 50 cm and it has constructed to DEM (Digital Elevation Model) based on GIS. Now it has used as an input topography information for the storm-surge inundation prediction models. Also it will be possible to use monitoring of beach process through the long-term periodic measurement and GIS-based 3D spatial analysis calculating the erosion and deposition considering with the artificial beach transition and coastal environmental parameters.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.3 no.4
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• pp.217-222
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• 1991

Hydralic model experiments for permeable breakwaters with three different shapes of cap concrete were carried out in a two-dimensional wave channel to investigate the shape effects of cap concrete on transmission rate of the incident waves over the breakwaters. The model test results show that energy damping effects are significant in the following order; cap concrete with dissipation holes and apron, cap concrete with apron only, and cap concrete without dissipation holes and apron. It is concluded that the significant damping effects are due to energy dissipation of the incident wave as they pass through the holes and the apron.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.15 no.4
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• pp.224-231
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• 2003

In this study, the hybrid breakwater system - a breakwater system combining the floating breakwater with the submerged breakwater - is used to improve the wave screening performance that may not be achieved by using the floating breakwater or the submerged breakwater, separately. Two-dimensional finite element method is used for numerical analysis and the wave reflection ratio and the wave transmission ratio are analyzed for the proposed case. In case of using the hybrid breakwater system, wave screening performance is more effective than in case of using the floating breakwater or the submerged breakwater, separately. It also shows an effective wave screening on the long wave period and an advanced wave screening performance with low height of the submerged breakwater.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.4 no.3
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• pp.139-145
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• 1992

In this paper, a technique to separate the incident and reflected waves in the flume tests is investigated. Using a least squares method, the separation technique has been formulated systematically. This method is applicable to the regular and irregular wave conditions. To illustrate its validity and applicability, numerical experiments have been carried out for both regular and irregular wave conditions. It was found that the method gives perfect results for the conditions without signal noises, and yields reasonable results even for the conditions with 30% signal noises of incident wave height. Hydraulic experiments have been also performed to prove its applicability of the method for real situations.