• 한국수자원학회:학술대회논문집
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• 한국수자원학회 2008년도 학술발표회 논문집
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• pp.624-628
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• 2008

Two-dimensional flow analysis is a way to provide good estimates for complex flow features in flow around islands and obstructions, flow at confluence and flow in braided channel. One of difficult problems to develop a two-dimensional hydraulic model is to analyze dry and wet area in river channel. Dry/wet problem can be encountered in river and coastal engineering problems, such as flood propagation, dam break analysis, tidal processes and so on. The objective of this study is to develop an accurate and robust two-dimensional finite element method with dry/wet technique in complex natural rivers. The dry/wet technique with Deforming Grid Method was developed in this study. The Deforming Grid Method was used to construct new mesh by eliminating of dry nodes and elements. The eliminated nodes and elements were decided by considering of the rising/descending velocity of water surface elevation. Several numerical simulations were carried out to examine the performance of the Deforming Grid Method for the purpose of validation and verification of the model in rectangular and trapezoidal channel with partly dry side. The application results of the model were displayed reasonable flow distribution.

• 한국수자원학회:학술대회논문집
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• 한국수자원학회 2008년도 학술발표회 논문집
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• pp.1619-1623
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• 2008

현재 섬진강 수계에서는 댐방류에 따른 하류하천의 하도추적은 수문학적 모형에 의해 운영되고 있으나, 하구의 조위 및 하천내 존재하는 수공구조물의 영향 그리고 지류에 의한 흐름분석을 위해서는 정교한 수리학적 모형이 필요하게 된다. 섬진강으로 유입하는 대표수계는 경천, 요천, 그리고 보성강이 있으며, 보성강의 상류에는 주암댐이 보성강의 유하량을 조절하게 되는 데 이를 반영한 모형구축을 지속적으로 수행할 예정이다. 또한 섬진강 하구유역에서는 조위에 의해 본류의 홍수위가 영향을 받게 되므로 이에 대한 영향도 분석하였다. 섬진강 하구에서는 여수관측소와 광양조위지점이 있는데, 두 지점 모두 일년치의 예측이 가능하게 되며 여수지점에서는 실시간 조위관측이 수행되고 있기 때문에 향후 두 지점의 조위결과값을 이용한 최적의 조위산정방법을 결정하게 된다. 본 모형은 하천에서 발생하는 부정류 수리학적 해석모형에 의해 다양한 수행결과를 제시하게 된다. 각각의 관측수위표지점과 비교한 결과 전체적인 경향에서는 합리적인 결과를 나타냄으로서 모형의 적합성을 확인할 수 있었다. 본 연구를 통하여 대상구간의 전체하도에 대한 적용절차 및 분석기법 등을 참조하여 다른 수계로의 확장이 가능하게 되었다. 단면변환 및 경계조건 산정방법, 모형의 수행 및 결과 분석 등이 댐방류 또는 지류의 유입을 고려한 합리적인 하천관리를 위한 방향을 제시할 것으로 판단된다.

• 한국환경과학회지
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• 제17권7호
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• pp.733-741
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• 2008

The object of this study is the safety insurance of the dam to provide for the extraordinary flood. The safety insurance of the reservoir was taken by the preparatory discharge using the temporary division tunnel used during the reservoir construction. In this study, the Sungju reservoir was simulated. The existing discharge facilities of the intake tower of the Sungju reservoir could nat have influence on the flood control. When the Sungju reservoir operated to begin preparatory discharge for 48 hrs by the temporary diversion tunnel that have discharge of an 20-years frequency, the water level was lowered about 20 cm. When the Sungju reservoir operated to begin the continuous discharge after the preparatory discharge, the water level was lowered over 1m but the downstream at risk was caused by the resulted. If it is possible to operate to begin the preparatory discharge of the reservoir for 24 hrs by the temporary diversion tunnel, that will improve the flood control faculty of the reservoir without other hydraulic structure and safety of the Sungju reservoir will be higher.

• 한국수자원학회논문집
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• 제30권1호
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• pp.35-44
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• 1997

Dynamic wavetlr의 Petrov-Galerkin 방법에 의한 유한요소모형을 점변 및 급변 부정류의 경우에 적용하였다. 정상도수, 마찰없는 수평수로상에서의 비선형 표면동요의 전달 및 댐 파괴 등의 급변 부정류의 경우에서 그 해석결과는 기존방법에 비해 우수하게 나타났고 해석적인 해와도 잘 일치되고 있었다. 본 연구모형은 마찰없는 수평수로상의 surge의 전파에 대하여 적용하여 급격한 선단부를 해석적인 해의 경우와 같이 재현할 수 있어 그 적용성을 입증하였다. 점변 부정류의 경우에는 태화강 하류부에 대해서 적용되었는데 그 계산결과는 수위, 유량의 수문곡선과 그 종단형상에 있어 기존의 DWOPER모형과 대등한 계산결과로 나타나 본 연구의 활용성을 입증하였다.

• 환경영향평가
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• 제18권6호
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• pp.331-346
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• 2009

The serious problem facing two-dimensional finite element hydraulic model is the treatment of wet and dry areas. This situation is encountered in most practical river and coastal engineering problems, such as flood propagation, dam break analysis and so on. Especially, dry areas result in mathematical complications and require special treatment. The objective of this study is to investigate the wet and dry parameters that have direct relevance to model performance in situations where inundation of initially dry areas occurs. Several numerical simulations were carried out, which examined the performance of the marsh porosity method of RMA-2 model to investigate for application of parameters. Experimental channel with partly dry side slopes, straight channel with irregular geometry and Han river were performed for tests. As a result of this study, effectively applied marsh porosity method provide a reliable results for flow distribution of wet and dry area, it could be further developed to basis for extending to water quality and sediment transport analysis.

• 한국물환경학회지
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• 제20권5호
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• pp.473-479
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• 2004

A sedimentation basin (SB) at the inlet of an irrigation reservoir which was constructed using an auxiliary dam was monitored to evaluate its pollutant removal efficiency. Water sampling at three points, i.e., inflow stream, upstream and downstream of the reservoir, were taken 5 times before and after the construction of the SB in 1999 and 2003, respectively. No significant water quality variations in inflow stream were observed during these periods. The COD, T-N, T-P and SS removal efficiencies were 38, 24, 35 and 49%, respectively. The results indicated that those removal efficiencies significantly increased during the rainy season and COD removal efficiency, especially, was higher than others studies. The scale of SB in this study was rational as aspects of pollutant removal efficiency and hydraulic detention time. And it is recommended that SB, at inlet of an reservoir, should be constructed as completely separated structure from reservoir water body and having SAR Index from 0.7% to 1.0%.

• 한국수자원학회논문집
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• 제38권2호
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• pp.155-166
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• 2005

상류이송기법은 불연속 흐름을 해석할 수 있기 때문에 댐붕괴류, 천이류 등의 해석에 많이 이용되고 있다. 그러나 상류이송기법은 생성항 처리과정에서 발생하는 오차로 인해 불균일한 단면을 가진 자연하천에는 거의 적용되지 못하고 단순화된 하도에만 주로 적용되어 왔다. 본 논문에서는 생성항의 차분화를 위해서 정규화된 Jacobian을 사용하는 상류이송형 생성항 처리기법을 개발하였다. 적용 결과 본 연구에서 제안된 생성항 처리기법이 정확하면서 효율적인 것으로 나타났다. 본 연구에서 제안한 방법은 단순한 형태를 지니고 있으며 다른 상류이송기법에도 다양하게 적용될 수 있을 것으로 판단된다.

• Smart Structures and Systems
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• 제21권2호
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• pp.195-205
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• 2018

Research on Lamb wave-based damage identification in plate-like structures depends on precise knowledge of dispersive wave velocity. However, boundary reflections with the same frequency of interest and greater amplitude contaminate direct waves and thus compromise measurement of Lamb wave dispersion in different materials. In this study, non-reflecting boundaries were proposed in both numerical and experimental cases to facilitate time-frequency characterization of Lamb wave dispersion. First, the Lamb wave equations in isotropic and laminated materials were analytically solved. Second, the non-reflecting boundaries were used as a series of frames with gradually increased damping coefficients in finite element models to absorb waves at boundaries while avoiding wave reflections due to abrupt property changes of each frame. Third, damping clay was sealed at plate edges to reduce the boundary reflection in experimental test. Finally, the direct waves were subjected to the slant-stack and short-time Fourier transformations to calculate the dispersion curves of phase and group velocities, respectively. Both the numerical and experimental results suggest that the boundary reflections are effectively alleviated, and the dispersion curves generated by the time-frequency analysis are consistent with the analytical solutions, demonstrating that the combination of non-reflecting boundary and time-frequency analysis is a feasible and reliable scheme for characterizing Lamb wave dispersion in plate-like structures.

• Geomechanics and Engineering
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• 제13권6호
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• pp.1027-1044
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• 2017

Membrane penetration is the most important factor influencing the measurement of volume change for triaxial consolidated-drained shear test for coarse-grained soil. The effective pressure p, average particle size $d_{50}$, thickness $t_m$ and elastic modulus $E_m$ of membrane, contact area between membrane and soil $A_m$ as well as the initial void ratio e are the major factors influencing membrane penetration. According to the membrane deformation model given by Kramer and Sivaneswaran, an analytical solution of the membrane penetration considering the initial void ratio is deduced using the energy conservation law. The basic equations from theory of plates and shells and the elastic mechanics are employed during the derivation. To verify the presented solution, isotropic consolidation tests of a coarse-grained soil are performed by using the method of embedding different diameter of iron rods in the triaxial samples, and volume changes due to membrane penetration are obtained. The predictions from presented solution and previous analytical solutions are compared with the test results. It is found that the prediction from presented analytical solution agrees well with the test results.

• 한국수자원학회논문집
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• 제41권7호
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• pp.725-735
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• 2008

최근 국내에서는 기상이변으로 인한 홍수피해가 증가하고 있으나, 환경, 경제 및 정치적 문제로 인해 댐과 같은 대규모 수공구조물의 설치가 어려우며, 이에 대안으로 천변저류지의 설치를 검토하기 시작했다. 천변저류지는 비교적 규모가 작아 대상유역에 설치가능한 후보지가 다수 존재하며, 이들 후보지를 적절히 조합할 경우 효율적인 홍수 조절효과를 기대할 수 있다. 그러나 천변저류지 후보지가 다수 존재할 경우 최대의 효과를 제공하는 조합을 결정하기는 어려우며, 특히 기존의 연구에서 천변저류지의 홍수조절효과 산정을 위해 사용한 부정류해석과 같은 수리학적 접근방법을 적용할 경우 분석에 한계가 있을 수 있다. 본 연구에서는 수문학적 접근방법을 이용하여 천변저류지의 홍수조절효과를 산정하고, 최적화 기법인 유전자알고리즘을 이용하여 다양한 경우에 대한 홍수조절효과를 효율적으로 산정하기 위한 의사결정모형을 개발하였다. 개발된 모형을 안성천수계에 적용하여 모형의 적용성을 검토하였으며, 개발된 모형은 천변저류지 계획 수립을 위한 의사결정모형으로 활용할 수 있을 것으로 판단된다.