• Proceedings of the Korea Water Resources Association Conference
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• 1992.07a
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• pp.101-108
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• 1992

하천에서의 2차원 흐름특성 해석을 위하여 2차원 shallow water식을 기본방정식으로 하고 이를 불연속보간 함수와 upwinding weighting을 도입한 petrov-Galerkin 방법에 의하여 해석하는 RIV-FEM2를 개발하였다. RIV-FEM2는 전처리(pre-processing), 주처리(analysis-processing), 후처리과정(post-processing)으로 구성되어 있다. 2차원 가상하도의 경우와 실제 하천에 대하여 본 모형을 적용한 결과 유속분포, 수면형 및 해석영역내에서의 mass flux의 보존등의 면에서 수렴성과 안정성이 뛰어나고 계산속도도 작게 나타나 본 모형의 적용성을 입증할 수 있었다. 본 연구를 통하여 개발된 RIV-FEM2는 실제의 하천에서의 수자원의 이수 및 치수관리면에서 크게 기여할 수 있을 것으로 판단된다.

• Journal of the Korean Geotechnical Society
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• v.19 no.5
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• pp.233-241
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• 2003

Geotextile tube is hydraulically filled with dredged materials and has been applied to coastal protection and scour protection, dewatering method of slurry, and isolation of contaminated material. Recently, geotextile tube technology is no longer alternative construction technique but suitable desired solution. In this paper, the numerical analysis was performed to investigate the behavior of geotextile tube with various properties of geotextile sheet and hydraulic pumping conditions. Numerical analysis was executed to compare with the results from the large-scale field model tests, and also with those of plane strain analysis and 3-D FEM analysis. A geotextile tube was modeled using the commercial finite element analysis program ABAQUS and the one-quarter of tube was modeled. Behavior of geotextile tube during the hydraulic pumping procedure was analyzed by comparing the large-scale field model test and numerical analysis. The shape variation and maximum tube height between the numerical analysis results and large-scale filed test results are turned out to be in a good agreement.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.31 no.6B
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• pp.507-514
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• 2011

A numerical model has been developed by employing a finite element method to simulate the depth-averaged 2-D dispersion of the heat pollutant, which is an important pollutant material in natural streams. Among the finite element methods, the Streamline Upwind/Petrov Galerkin (SUPG) method was applied. Also both linear and quadratic elements can be applied so that irregular river boundaries can be easily represented. To show the movement of heat pollutants, the reaction term describing heat transfer was represented as an equation in which sink/source term is proportional to the difference between the equilibrium temperature and water surface temperature. The equation was expressed so that the water surface temperature changes according to the temperature transfer coefficient and the equilibrium temperature. For the calibration of the model developed, analytic and numerical results from a case of rectangular channel with full width continuous injection have been compared in a steady state. The comparisons showed that the numerical results were in good agreement with analytical solutions. The application site was selected from the downstream of Paldang dam to Jamsil submerged weir, and overall length of this site is about 22.5 km. The change of water temperature caused by the discharge from the Guri sewage treatment plant has been simulated, and results were similar to the observed data. Overall it is concluded that the developed model can represent the water temperature changes due to heat transport accurately. But the verification using observed data will further enhance the validity of the model.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.7 no.3
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• pp.89-98
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• 1987

Analyzed by using finite element method was 2-dimensional pollutant transtport phenomenon considering longitudinal and lateral direction in river. The Galerkin's finite element method based on linear interpolation is used and triangle is adopted as an element. In a number of model test attempts it has been demonstrated that the results calculated by the model are in good agreement with analytical solutions in a simplified channel where there is a known solution available. Actual application of the model is attempted along the 9km reach of the Han River considering the influx of the Tan Cheon and the Joongryang Cheon. The resultant 2-dimensional BOD concentrations profile in the reach is exhibiting more realistically the field situations than conventional 1-dimensional models are.

• Proceedings of the Korea Water Resources Association Conference
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• 2001.05b
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• pp.993-998
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• 2001

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.8 no.1
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• pp.103-113
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• 1996

Two-dimensional finite element hydrodynamic models for long wave simulation usually adopt fixed land boundary. However moving boundary treatment is strongly required in the simulation of tidal flats for west and south coast of Korea. In this study very efficient and realistic moving boundary treatment is applied by considering incident long wave surface slope. Developed STEP-CM (Superior Two-step Explicit Program for Coastal Modeling) ,shows numerically stable results in comparative study for idealized one-dimensional channel. Real application of the model is done for Chonsu Bay where tidal flats are distributed along the coast. Nonlinear tidal current and tidal flat effects are easily simulated in STEP-CM and resulting circulations are detected around headland of Wonsan Island.

• 한국방재학회:학술대회논문집
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• 2010.02a
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• pp.98.1-98.1
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• 2010

본 연구에서는 한강 본류 팔당댐부터 잠실수중보까지의 22.5 km 구간에서 발생할 수 있는 수질 오염사고에 대한 오염물질 혼합거동 모의를 위해 RAMS를 이용하였다. 이를 위해서 2차원 흐름모형인 RAM2를 이용하여 유속장을 모의하고, 2차원 수질해석 모형인 RAM4를 이용하여 사고주입에 의한 오염물질의 시간에 따른 거동을 분석하였다. 최종적으로 잠실수중보에 위치한 주요 취수장에 미치는 영향을 분석하였다. 모의를 진행한 결과 오염물질의 이송 및 확산 거동은 투입 위치에 따라 크게 달라진다는 것을 알 수 있었다. 특히 팔당대교에서 투입된 오염물질이 풍납 취수장에 도착하는데 까지 걸리는 시간이 좌안주입과 우안주입의 경우 60시간 가까이 차이가 나는 것으로 나타났다. 따라서 오염 물질이 투입되었을 시에 일괄적으로 취수를 통제할 것이 아니라 상황에 따라 오염물질 투입 지점에 맞춰서 적절한 대책을 세워야 하는 것이 필요하다. 이 때 본 연구가 기초적인 정보를 제공할 수 있을 것이다.

• Geophysics and Geophysical Exploration
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• v.2 no.1
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• pp.43-53
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• 1999

Numerical modeling and inversion for electromagnetic exploration methods are essential to understand behaviour of electromagnetic fields in complex subsurface. In this study, a finite element method was adopted as a numerical scheme for the 2.5-dimensional forward problem. And a finite element equation considering linear conductivity variation was proposed, when 2.5-dimensional differential equation to couple eletric and magnetic field was implemented. Model parameters were investigated for near-field with large source effects and far-field with responses dominantly by homogeneous half-space. Numerical responses by this study were compared with analytic solutions in homogeneous half-space. Blocky inversion model was modified to be applied to the forward calculation in this study and it was also adopted in the inversion algorithm. Resolution for isolated bodies were investigated to confirm possibility and limitation of inversion for electromagnetic exploration data.

• Bulletin of the Society of Naval Architects of Korea
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• v.27 no.2
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• pp.21-30
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• 1990

Theoretical and experimental techniques to analyze the two-dimensional liquid motion in a tank are discussed. A Lagrangian FEM with a velocity correction procedure is introduced to describe incompressible free surface fluid flow. A mesh rezoning technique is used to prevent strong distortion of finite elements in the Lagrangian description. Model test technique for sloshing tank is developed using a hydraulic type bench tester. The influence of the variation in the exciting frequency and amplitude are observed for various fill depths. The results of theoretical calculations are compared with those of experiments.

• Proceedings of the Korea Water Resources Association Conference
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• 2009.05a
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• pp.764-769
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• 2009

하천과 바다가 만나는 하구는 자연적인 기능 뿐만 아니라 공학적인 측면에서도 매우 중요한 자원이다. 우리나라는 국토의 개발에 따른 용수 사용의 증가, 홍수재해대책 등으로 인해 한강을 제외한 4대강에 하구둑을 건설하였으며 강물과 바닷물을 인위적으로 차단하는 구조물이므로 하천의 생태적인 기능을 손상시키는 것은 불가피 하다. 하지만 이러한 단점에도 불구하고 하구둑이 건설되는 가장 큰 목적 중의 하나는 주변지역의 안정된 용수공급이다. 1987년에 완공된 낙동강 하구둑은 건설 이 후 약 20년 동안 안정된 용수공급과 효율적 운영으로 관리되어 왔지만 그동안 기상 및 수리 수문뿐만 아니라 환경적으로 크고 작은 변화가 있었다. 하천의 기수역인 하구에서 유체는 하구둑이라는 구조물이 존재하지 않을 때도 매우 복잡하게 거동한다. 하천의 유량, 지형학적 요소 그리고 조위의 상태 등 여러 가지 요인으로 인하여 비정상적으로 변화하며 이러한 하구에서 유체의 거동을 보다 더 정확하게 묘사하려면 흐름방향, 수심방향, 하폭방향의 3차원적인 해석이 필요하다. 하지만 하천과 바다를 밀도가 같은 하나의 상으로 가정하고 수행한 수문학적인 분석이나 1 2차원 수치모형을 활용한 수리 분석 결과는 시간적 공간적으로 경제적이고 양호한 결과를 산출해낼 수 있다. 본 연구에서는 낙동강 하구둑의 수리특성을 분석하기 위하여 미국 기상청의 홍수추적모형인 FLDWAV 모형과 미수로국(WES)의 2차원 유한요소 모형인 RMA-2 모형을 활용하였으며 낙동강유역 주요 수위관측소의 실측자료를 토대로 매개변수 검정을 실시하였다. 분석결과 조위가 고려된 2차원 유속장을 구현하였으며 하구둑 유지 관리 개선에 기여코자 하였다.