• 한국지하수토양환경학회:학술대회논문집
• /
• 한국지하수토양환경학회 2000년도 추계학술대회
• /
• pp.74-77
• /
• 2000

Infiltration and water flow in the upper soil layer of a deep water table aquifer are modeled for multistorm runoff events. The infiltration process is developed using the sharp wetting front model of Green and Ampt, and the following redistribution process is modeled using the gravity drained rectangular approximation. The Brooks-Corey model [Brooks and Corey, 1966] is adopted to relate the effective soil saturation, the tension head, and the unsaturated hydraulic conductivity Firstly, the infiltration and redistribution model is developed for a single stom runoff event. Then a couple of events combined for multistorm runoff events. In the later case, infiltration rate of the second rainfall is strongly influenced by the length of the rainfall hiatus and soil moisture profile.

• Journal of the Korean Society for Industrial and Applied Mathematics
• /
• 제21권3호
• /
• pp.109-124
• /
• 2017

The numerical solution of the Stokes equation with discontinuous viscosity and singular force term is challenging, due to the discontinuity of pressure, non-smoothness of velocity, and coupled discontinuities along interface.In this paper, we give an efficient algorithm to solve this problem by employing spectral Legendre and Chebyshev approximations.First, we present the algorithm for a problem defined in rectangular domain with straight line interface. Then it is generalized to a domain with smooth curve boundary and interface by employing spectral element method. Numerical experiments demonstrate the accuracy and efficiency of our algorithm and its spectral convergence.

• 한국안전학회지
• /
• 제16권4호
• /
• pp.208-212
• /
• 2001

미분구적법(DQM)을 이용하여 헬리컬 스프링(helical spring)의 2차원적 탄성 문제를 계산하였다. 헬리컬 스프링의 직사각형 및 정사각형 단면적에 축방향 하중(axially loaded)이 작용했을 때의 탄성 전단 응력(elastic shear stress)을 계산하였다. 미분구적법의 결과를 다른 수치해석(successive approximation) 결과와 비교하였으며, 미분구적법은 적은 요소(grid point)를 사용하여 정확한 해석결과를 보여주었다

• Structural Engineering and Mechanics
• /
• 제53권1호
• /
• pp.131-146
• /
• 2015

In the present paper a three-dimensional non-linear truss element and a short computer program for the modeling and predicting approximate lateral deflections in thin glass plates by the method of incremental loading are proposed. Due to the out-of-plane large deflections of thin glass plates compared to the plate thickness within each loading increment, the equilibrium and stiffness conditions are written with respect to the deformed structure. An application is presented on a thin fully tempered monolithic rectangular glass plate, laterally supported around its perimeter subjected to uniform wind pressure. The results of the analysis are compared with published experimental results and found to have satisfactory approximation. It is also observed that the large deflections of a glass plate lead to a part substitution of the bending plate behavior by a tensioned membrane behavior which is favorable.

• Journal of Ship and Ocean Technology
• /
• 제7권3호
• /
• pp.34-55
• /
• 2003

Explicit Kutta condition approximation, proved useful in existing time-domain solver of the unsteady propeller problem, requires a specified functional behavior of the vorticity in space near the trailing edge. In this paper, the strength of the discrete vortices is controlled to have a specified behavior in space in the frequency domain approach. A new formulation is introduced and is implemented for analysis of a lifting surface of a rectangular planform. Sample computations carried out according to the new formulation compares well with that of existing unsteady lifting problem in the time domain.

• Nuclear Engineering and Technology
• /
• 제49권1호
• /
• pp.29-42
• /
• 2017

The purpose of the present study is the presentation of the appropriate element and shape function in the solution of the neutron diffusion equation in two-dimensional (2D) geometries. To this end, the multigroup neutron diffusion equation is solved using the Galerkin finite element method in both rectangular and hexagonal reactor cores. The spatial discretization of the equation is performed using unstructured triangular and quadrilateral finite elements. Calculations are performed using both linear and quadratic approximations of shape function in the Galerkin finite element method, based on which results are compared. Using the power iteration method, the neutron flux distributions with the corresponding eigenvalue are obtained. The results are then validated against the valid results for IAEA-2D and BIBLIS-2D benchmark problems. To investigate the dependency of the results to the type and number of the elements, and shape function order, a sensitivity analysis of the calculations to the mentioned parameters is performed. It is shown that the triangular elements and second order of the shape function in each element give the best results in comparison to the other states.

• 자원환경지질
• /
• 제18권2호
• /
• pp.159-166
• /
• 1985

Multipole 확장에 의한 중력이상의 계산식이 유도되고, 직각 prism과 원기둥 모양의 물체에 대하여 중력을 계산하며 정확한 계산과 비교 연구를 한다. 근거리에 있는 source의 multipole확장은 표면적분보다 체적적분이 더 좋은 근사치를 얻게한다. 그렇지만 지구물리탐사의 실제에 있어 흔히 나타나는 원거리의 source에 대해서는 이 두 접근 방법은 서로 일치하게 됨을 알 수 있다.

• 한국항만학회지
• /
• 제7권1호
• /
• pp.79-88
• /
• 1993

This study deals with the case of a fixed floating structure(FFS) at the mouth of a rectangular harbor under the action of waves represented by the linear wave theory. Modified forms of the mild-slope equation is applied to the propagation of regular wave over constant water depth. The model is extended to include bottom friction and boundary absorption. A hybrid element approximation is used for calculation of linear wave oscillation in and near coastal harbor. Modification of the model was necessary for the FFS. For the conditions tested, the results of laboratory experiments by Ippen and Goda(1963), and Lee (1969) are compared with the calculated one from this model. The cases of flat cylinderical structures, both fixed and floating, were taken to be in an intermediate water depth.

• Structural Engineering and Mechanics
• /
• 제72권1호
• /
• pp.131-139
• /
• 2019

According to the properties of monoclinic materials, the normal and shear stresses are depending on both normal and shear strains. In the current investigation, the static analysis of monoclinic plates based on three dimensional elasticity theory is investigated. New governing equations and boundary conditions are derived for monoclinic plates and the Differential Quadrature Method (DQM) is used to solve the static problem. In our method of solution, no approximation is used and the DQM is adopted in all directions. By showing the differences between our results and the results for especially orthotropic plates, one can find that it is worth to investigate the monoclinic plates to have more accurate results.

• 한국재료학회지
• /
• 제10권10호
• /
• pp.698-702
• /
• 2000

$Al_{0.24}Ga_{0.76}As/GaAs$ 다중 양자우물 구조의 고아 흡수 특성을 표면 광전압 방법을 사용하여 연구하였다. SPV 측정결과 1.42eV 부근에서 두 개의 신호가 나탔으며, 이는 화학적 에칭으로 GaAs 기판의 신호와 GaAs 완충층과 관련된 신호임을 확인 할 수 있었다. $Al_{0.24}Ga_{0.76}As$와 관련된 전이 에너지를 관찰하고, Kuech 등이 제안한 조성식을 이용하여 Al 조성(x=24%)을 결정하였다. 그리고 다중 양자우물에서 나타나는 전이 에너지 값들은 envelope-weve function approximation(EFA)로 계산한 이론치와 잘 일치하였다. 입사광의 세기에 따라 광 전압이 선형적으로 변한다는 것을 알 수 있었고, 온도가 감소함에 따른 전이 에너지의 변화를 관찰하였다.