• Earthquakes and Structures
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• 제14권2호
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• pp.167-178
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• 2018

A roller compacted concrete (RCC) dam should be analyzed under seismic ground motions for different conditions such as empty reservoir and full reservoir conditions. This study presents three-dimensional earthquake response and performance of a RCC dam considering materially non-linearity. For this purpose, Cine RCC dam constructed in Aydın, Turkey, is selected in applications. The three-dimensional finite element model of Cine RCC dam is obtained using ANSYS software. The Drucker-Prager material model is considered in the materially nonlinear time history analyses for concrete and foundation rock. Furthermore, hydrodynamic effect was investigated in linear and non-linear dynamic analyses. Researchers observe that how the tensile and compressive stresses change by hydrodynamic pressure effect. The hydrodynamic pressure of the reservoir water is modeled with the fluid finite elements based on the Lagrangian approach. In this study, dam body and foundation are modeled with welded contact. The displacements and principle stress components obtained from the linear and non-linear analyses with and without reservoir water are compared each other. Principle stresses during earthquake were obtained at the most critical point in the upstream face of dam body. Besides, the change of displacements and stresses by crest length were investigated. Moreover demand-capacity ratio criteria were also studied under linear dynamic and nonlinear analysis. Earthquake performance analyses were carried out for different cases and evaluated. According to linear and nonlinear analysis, hydrodynamic water effect is obvious in full reservoir situation. On the other hand, higher tensile stresses were observed in linear analyses and then non-linear analyses were performed and compared with each other.

• 한국해안해양공학회지
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• 제6권1호
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• pp.1-11
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• 1994

곡선형격자 삼차원 수치모델이 소개되며 바람에 의한 물의 순환을 계산하기 위하여 얕은 호수에서 적용되었다. 수치모델의 결과가 실측자료와 비교되었으며, 바람이 점차 증가할 때 물의 성층에 의한 효과가 좋은 계산 결과를 얻기 위하여 결정적임을 알 수 있었다. 기상자료가 불충분할 때 소위 Inverse Method가 물 표면에서 열흐름을 추정하기 위하여 사용되었다.

• 한국전산유체공학회지
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• 제12권4호
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• pp.44-53
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• 2007

A three-dimensional (3D) unstructured hydrodynamic solver for transient two-phase flows has been developed for a 3D component of a nuclear system code and a component-scale analysis tool. A two-fluid three-field model is used for the two-phase flows. The three fields represent a continuous liquid, an entrained liquid, and a vapour field. An unstructured grid is adopted for realistic simulations of the flows in a complicated geometry. The semi-implicit ICE (Implicit Continuous-fluid Eulerian) numerical scheme has been applied to the unstructured non-staggered grid. This paper presents the numerical method and the preliminary results of the calculations. The results show that the modified numerical scheme is robust and predicts the phase change and the flow transitions due to boiling and flashing very well.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2003년도 춘계학술대회 논문집
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• pp.207-210
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• 2003

The chemical mechanical planarization (CMP) process is a method of planarizing semiconductor wafers with a high degree of success. However, fundamental mechanisms of the process are not fully understood. Several theoretical analyses have been introduced, which are focused on kinematics, von Mises stress distributions and hydrodynamic lubrication aspects. This paper is concerned with hydrodynamic lubrication theory as the chemical mechanical planarization model; the three-dimensional Reynolds equation is applied to predict slurry film thickness and pressure distributions between the pad and the wafer. This paper classifies geometry of wafer into 3 types and focuses on the differences between them.

• 한국전산유체공학회:학술대회논문집
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• 한국전산유체공학회 2007년도 추계 학술대회논문집
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• pp.243-248
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• 2007

A three-dimensional (3D) unstructured hydrodynamic solver for transient two-phase flows has been developed. A two-fluid three-field model was adopted for the two-phase flows. The three fields represent a continuous liquid, an entrained liquid, and a vapour field. The hydrodynamic solver is for the 3D component of a nuclear system code and the component-scale analysis tools for transient two-phase flows. The finite volume method and unstructured grid are adopted, which are useful for the flows in a complicated geometry. The semi-implicit ICE (Implicit Continuous-fluid Eulerian) numerical scheme has been adapted to the unstructured non-staggered grid. This paper presents the numerical method and the preliminary results of the calculations. The results show that the numerical scheme is robust and predicts the phase change and the flow transitions due to boiling and flashing problems well.

• 한국방재학회:학술대회논문집
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• 한국방재학회 2008년도 정기총회 및 학술발표대회
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• pp.179-182
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• 2008

This study simulated the flood inundations of the Nakdong River catchment running through Yangsan, a small city located in the south eastern area of Korea by using the depth averaged two-dimensional hydrodynamic numerical model. The numerical model employs the staggered grid system including moving boundary and a finite different method to solve the Saint-Venant equations. A second order upwind scheme is used to discretize the nonlinear convection terms of the momentum equations, whereas linear terms are discretized by a first order leap-frog scheme(Cho and Yoon, 1998). The numerical model was applied to a real topography to simulate the flood inundation of the Yangsan basin. The numerical results for urban district are visualized in three dimension. These results can be essentially utilized to construct the three dimensional inundation map after building the GIS-based database in local public organizations in order to protect the life and property safely.

• 한국해양학회지
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• 제18권1호
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• pp.10-20
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• 1983

京畿灣의 三次元 流動 解析모델이 開發되었으며 이 모델을 利用하여 定常一風인 10dyne/$\textrm{cm}^2$의 剪斷强度를 갖는 北西風 및 西風에 의한 京畿灣의 反應을 數値實驗하였다. 算定된 바람 應力에 의한 三次元 海流分布가 檢討되었다. 모델은 또한 京畿灣의 主要한 物理現狀인 主太陰半日週潮(M$_{2}$)의 分布를 算定하는데 理容되었는데 潮流의 三次元 分布에 대한 初期缺課가 提示되고 討議되었다.

• 한국수산과학회지
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• 제29권3호
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• pp.369-385
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• 1996

가막만 식물플랑크톤에 대한 기초생산력을 산정하기 위해 해수유동모델과 생태계 모델을 이용하였다. 이를 위해 양식기간동안 양식장이 없는 조건으로 식물플랑크톤에 대한 기초생산력을 산정하였으며 그 결과는 다음과 같다. 양식장이 없는 경우로 월별 식물플랑크톤을 예측한 결과로 월별 식물플랑크톤량의 변화를 보면 6월부터 증가하기 시작하여 9월이 가장 높은 식물플랑크톤량을 보이고 9월부터 12월까지 급격히 감소하다가 그 이후 3월까지 서서히 감소하였다. 양식장이 없는 경우로 월별 식물플랑크톤에 대해 계산한 기초생산력을 보면 양식기간 동안 범위는 $0.99\~10.20gC/m^2/d$로 평균 $4.43gC/m^2/d$이였다. 월별 변동을 보면 6월부터 급격하게 증가하기 시작하여 8월에 가장 높은 생산력을 보이고 8월 이후 12월까지 급격히 감소하다가 1월 이후에 3월까지 서서히 증가하는 경향을 보였다.

• 한국수자원학회논문집
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• 제38권1호
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• pp.83-96
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• 2005

해안매립이 해양의 동수력학, 환경 및 생태계에 미치는 영향을 분석하기 위하여 3차원 동수력학 수치해석을 실시하였다. 이 연구에서는 방조제 건설에 따른 조석, 바람 및 밀도변화 성분을 포함한 조류와 잔차류의 변화를 수치모의 하였다. $\sigma$-좌표로 변환된 지배방정식은 음해유한차분법을 이용하여 해석하였다. 수치모형은 조석의 4대 주요 구성성분인 M$_2$, S$_2$, $K_1$ 및 $O_1$의 조석표를 이용하여 검증하였다. 수치해석결과, 주로 조석 및 바람에 의한 잔차류의 변화가 큰 것으로 나타났다.

• 한국해양공학회지
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• 제20권1호
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• pp.55-62
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• 2006

Recently, pollution by development in coastal areas is going from bad to worse. The Korean government is attempting to make policies that prevent water pollution, but it is still difficult to say whether such measures are lowering pollution to an acceptable level. More specifically, the general investigation that has been done in KOREA does not accurately reflect the actual conditions of pollution in coastal areas. An investigation that quantitatively assesses water quality management using rational prediction technology must be attempted, and the ecosystem model, which incorporates both the 3-dimensional hydrodynamic and material cycle models, is the only one with a broad enough scope to obtain accurate results. The hydrodynamic model, which includes advection and diffusion, accounts for the ever-changing flow and (quality) of water in coastal areas, while the material cycle model accounts for pollutants and components of decomposition as sources of the carbon, phosphorus, and nitrogen cycles. In this paper, we simulated the rates of dissolved oxygen (DO), chemical oxygen demand (COD), total nitrogen(T-N) and total-phosphorous(T-P) in Korea's Ulsan Area. Using the ecosystem model, we did simulations using a specific set of parameters and did comparative analysis to determine those most appropriate for the actual environmental characteristics of Ulsan Area. The simulation was successful, making it now possible to predict the likelihood of coastal construction projects causing ecological damage, such as eutrophication and red tide. Our model can also be used in the environmental impact assessment (EIA) of future development projects in the ocean.