• Proceedings of the Korea Water Resources Association Conference
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• 1987.07a
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• pp.261-261
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• 1987

황해의 조석 역학을 포함한 중규모 순환을 연구하기 위해 수립되었던 황해 조석 모델(최, 1980 ; 최, 1984)을 세격자체계로서 개선하였다. 과거 기본모델의 위도 1/5도, 경도 1/4도의 해상도(약 12 해리)는 본 모델에 의해 위도 1/15도, 경도 1/12도의 세격자체계로서 육붕 전역을 자세히 해상시켰다. 모델은 일차적으로 주태음반일주조에 의한 황해의 평균 조석 상황을 재현시키는데 이용되었으며 산정된 조류의 검증은 86년 동계의 해양관측중 해류관측결과(미국 Florida 주립대 - 성균관대 협력연구)로서 수행하였다. 계산 결과에 의하면 과거 모델보다 높은 해상력에 의해 연안에서의 조석 파급 효과가 개선되게 산정되었으므로 연안 해양학적인 각종 응용에 더 나은 입력 및 해석에 이용될 수 있다. 계산 시간간격은 69.00333초로서 1태음조석 주기당 648 timestep 을 형성하였는데 매 조석주기당 약 80 C.P.U.(분)이었으며 7번째 조석주기의 산정 결과를 분석하는데 이용하였다. 본 연구는 기보고된 세계 여타 해역의 육붕모델보다도 자세한 해상도를 갖는 3차원 모델의 결과로서 여겨진다. 아마도 육붕단의 조석 관측이 모델 개선을 위해 필수적인 사항으로 대두되는데 이는 조석 입력(예: 구주 서측 deamphidromic zone)의 중요성이 판별되었기 때문이다. 모델을 이용한 추후의 연구는 극한 상황의 3차원적 해류 분포, 대륙붕 해저 경계층 연구를 포함하는 퇴적 역학 연구 등이 될 것이다.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.15 no.3
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• pp.190-195
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• 2003

For many coastal problems, such as wave transformation, tidal circulation, sediment transports and diffusion phenomena, we resort to numerical techniques. The representative numerical techniques are the method of finite differences and finite elements. The approximate algebraic equations, referred to as finite difference equations(FDEs), are subsequently solved at discrete grid points within the domain of interests. Therefore, a set of grid points within the domain, as well as the boundaries of the domain, must be specified. The generation of grids for FDEs, with uniform spacing, is very simple compared to that of finite elements. However, within a very complex domain, there are few grid generation tools we can use conveniently. Unfortunately, most of the commercial grid generation programs are developed only for finite element method. In this paper, grid generation method using digitizer, with uniform rectangular spacing, are introduced in detail. Didger and Surfer programs by Golden Software are necessary to produce comparatively accurate and simple depth data.

• Journal of the Korean Association of Geographic Information Studies
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• v.22 no.4
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• pp.158-168
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• 2019

Korea Hydrographic and Oceanographic Agency(KHOA) carried out a research project named 'Marine Fisheries Infrastructure Construction and Technology Training for the Philippines' as part of the 1st Official Development Assistance(ODA) from 2015 to 2018. It is preparing for the 2nd ODA project which will begin in 2020. Besides, recently, the Philippines is paying attention to marine territory management and response capability due to problems such as the sea-level rise and coastal erosion caused by climate change. Therefore, before 2nd ODA to the Philippines, this study analyzed the vertical ocean model on the vertical datum in Korea and suggests the direction of development of the vertical ocean modeling system for the vertical datum in the Philippines using the observed data from the permanent tide station which was built by the Philippines ODA research project over the last four years. Moreover, as a pilot study, the Sulu Sea in the Philippines was selected and analyzed by harmonic analysis method. At each tide station, constants for correction had been computed. And the grid-based tidal model was constructed based on this study. As a result of the study, similar tidal characteristic were observed when the prediction and the measured tide were compared by applying the constants for correction between two station in the sea area with similar tidal level. These results could be used as basic data for the 2nd ODA to the Philippines, and contributed to construct and maintain a close cooperation and friendship between Korea and the Philippines.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.19 no.3
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• pp.253-265
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• 2007

This study applied the previous results of the NAO model, a tidal correction model, to the open boundary condition for the behavior of tidal elevation and tidal currents in the South Sea. This study used the EFDC model considering the wetting and drying problem and using the $\sigma-coordinate$ as a vertical coordinate and generated two mesh cases of the constant grid size of 2.0 km and the variable grid size of $0.5\sim2.0km$. The numerical results for the tides showed that the predicted results were in quite good agreements with the observational data acquired from the tidal stations of the NORI. The predicted tides were observed to propagate from the east area to the west area in the South Sea. The verification results reveal that the numerical results are more correlated with the measured tidal data as the grid size decreases. The grid size of 2 km results in proper simulation of tidal currents in wide waterway and offshore area whereas the numerical results from the grid size of 0.5 km tend to somewhat underestimate the tidal currents affected by narrow waterway and topography in inner-bay.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.15 no.1
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• pp.51-61
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• 1997

A two-dimensional numerical tidal model with $1/3^\circ$ resolution has been established to investigate the distribution of semidiurnal constituents$(M_2,\;S_2,\;K_2,\;N_2)$ and diurnal constituents$(K_1,\;O_1,\;P_1,\;Q_1)$ of the global ocean. The $1/3^\circ$ numerical model has been applied to the computation of detailed tidal distributions in the marginal seas and the shelf seas. Tidal characteristics in shallow areas could be hardly resolved with the existing global chart due to the low resolution. Computed tidal charts obtained by $1/3^\circ$ numerical model have been compared with the existing global charts and the altimetry-derived tidal charts. Computed harmonic constants have also been com-pared with the pelagic tidal observations. The results obtained with fine-grid numerical model can be used to determine the time-independent sea surface topography by removing the tidal components from the altimetry-derived sea surface height.

• 한국해양학회지
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• v.12 no.1
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• pp.33-40
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• 1977

British Hydraulics research Station's Sparse Scheme was suggested for the solution of two dimensional finite difference tidal equations. 2D-numerical tidal model formed with 4.8km rectangular cells was set up to find out the barrage effects on tidal ranges of some possible areas for tidal power generation in Korea. The comparisons were made hetween spring tidal ranges with and without barrages at the entrance of Asan Bay, Garorim bay, Cheonsu bay and near Incheon Bay. Because of the coarseness of the grid, the model results could not represent the values of changes precisely. However the results show that the tidal amplitude near Incheon Bay increased by about 40cm by setting a barrage and about 50cm increase near the entrance of Asan Bay, respectively. But there were only a few centimeter changes in other areas.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.19 no.5
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• pp.457-466
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• 2007

The effect of depth correction in the coastal sea has been investigated through a series of tide simulations in the area of $115{\sim}150^{\circ}E,\;20{\sim}52^{\circ}N$ of northwestern Pacific with $1/12^{\circ}$ resolution. Comparison of the solutions varying the minimum depth from 10m to 35 m with the 5m interval shows that the amplitude accuracies of $M_2,\;S_2,\;K_1$ tide using the minimum depth of 25 m have been improved up to 42%, 32%, 26%, respectively, comparing to those using the minimum depth of 10m. The discrepancy between model results using different minimum depth is found to be up to 20 cm for $M_2$ tidal amplitude around Cheju Islands and the positions of amphidromes are dramatically changed in the Bohai Sea. The calculated ARE(Averaged Relative Error) values have been minimized when the bottom frictional coefficient and the minimum depth is 0.0015 and 25 m, respectively.

• Water for future
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• v.22 no.3
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• pp.315-322
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• 1989

The effects of open boundary conditions including the radiation condition are compared by utilizing the $L^{2_}$-norm and RMS error in the numerical modeling of ocean problem. In numerical tests of $M_2$ tide, grid size and bed roughness are considered and analyzed. For the $M_2$ tide test in a simplified bay where the analytical solutions are available, it is found that improved radiating boundary condition(IMPSOM) may increase the reliability of computed results by 40% of $L^{2_}$-norm and 96% of RMS error than the open boundary condition without radiation effect. In case of using the half-size grids, better results are obtained. It is also found that the IMPSOM is applicable with satisfaction when the bottom friction is included.

• Water for future
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• v.23 no.3
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• pp.319-328
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• 1990

The Parameter Identification of 2-demensional estuarine model was carried out using new output ADI-FDM numerical semi-implicit schem transformed in boundary fitted(BF) - coordinate. The hydrodynamic equations which is coupled with the transport equations were used as basic equations in the model. Thompson's equations were used to transform governing equations into rectangular plane equations and his elliptic grid generation scheme was used to generate curvilinear grid system. in BF - coordinates. The parameters to be identified are friction coefficient and disperse coefficient embedded in the governing equations. The numerical output scheme is tidally averaged salinity model in BF - coordinates. The algorithm to optimize norm of error between observations and calculations is the influence coefficinet algorithm associated with least square criterion. The lumped model is conssidered in identification. This paper was concetrated on checking whether the new output scheme might be useful to identify parameters in estuarine salinity model or not. The proposed method was tested through experimental application with hypothetical simple model. The result of the test shows that the proposed method can be used for parameter identification in estuarine model.

• Proceedings of the Korea Water Resources Association Conference
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• 2009.05a
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• pp.2018-2022
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• 2009

본 연구에서는 낙동강 하구둑의 주요 기능 중에서 용수공급에 지장을 초래하는 염수침입 및 염해피해 방지 효과에 대하여 재평가 하고자 한다. 평가범위는 수치모형을 이용하여 낙동강 하구둑 건설 이전의 지형상황을 재현하고, 하구둑이 없는 조건 하에서 상류유입유량을 변화시키며 외해를 통한 염분 침입 가능범위를 수치모의 함으로서 하구둑의 효과를 간접적으로 평가하였다. 연구에 사용된 수치모형인 EFDC 모형 입력자료로 낙동강 하류부 및 외해 수역에 대한 3차원 지형도를 작성하였고. 평면 직교곡선격자망을 이용하여 대상 지역을 분할하였다. 초기조건으로 전 수역을 담수(염도 0.0psu)로 가정한 상태에서 하류단 경계에 실측 조위 및 해수조건(염도 33psu)을 적용하고 상류단에는 $50m^3/sec$를 적용하여 약 20일간 수행된 결과를 사용하였다. 상류유입유량을 $10^{\sim}250m^3/sec$의 범위로 변화시키고, 하류단 경계조건으로 조위를 적용하여 수치모의를 수행한 결과 염수침입현상에 제일 큰 영향을 미치는 요소는 상류로부터 유입하는 유량인 것으로 나타났다. 그 이외에 담수와 해수의 밀도 차이에 인한 밀도류형성 및 조석에 의한 염수의 밀어올림현상이 하류에서 상류로 염수가 침입하는데 다소의 영향이 있었다. 유입유량이 $250m^3/sec$에서 $10m^3/sec$로 감소할 경우 염분농도 1psu의 도달범위는 11km에서 50km정도로 증가하였다.