• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 1999.10a
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• pp.61-64
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• 1999

산성침출수에 의한 광산폐기물 매립지 근처의 지하 환경의 오염 및 대처 방안의 효과를 수치적으로 예측하였다. 이를 위하여 지하토양에서 Darcy 법칙을 사용한 침출수의 흐름과 이산-분산에 의한 오염물질의 이동현상을 예측하기 위하여 Galerkin 유한요소법을 활용하였다. 토양오염의 지연을 위하여 석회석 차수막을 연직형과 수평형을 도입하여 그 효과를 조사하였다. 수평차수막에서의 수착이 오염물질의 이동을 지연시키는데 상당한 효과가 있는 것으로 나타났다. 반면에 연직차수막은 지하수의 우회유동으로 인한 오염물질의 확산이 가중되고 있는 것으로 예측되었다. 전반적으로 침출수의 흐름은 광산매립지 제방 근처에서 강하게 일어나는 것으로 나타났다. 이를 근거로 차수막의 효과적인 설치방안이 고안되어야 할 것으로 보인다.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 1998.06a
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• pp.33-37
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• 1998

본 연구에서는 다공성 지하에서 침출수에 지하 환경의 오염 및 대처 방안의 효과를 수치적으로 예측하였다. 연구대상으고 매립지 지하에서의 침출수의 흐름은 Darcy 법칙을 사용하여 해석하였고, 오염물질의 이동은 이산-분산 모델에 수착의 효과를 고려하여 해석하였다. 침출수의 흐름 및 오염물질의 이동 방정식을 2차원 계를 대상으로 하여 Galerkin유한 요소법을 사용하였다. 수치해석 결과 침출수의 흐름은 매립지 제방 근처에서 강하게 일어나는 것으로 나타났다. 연직 차수막은 오염물질의 이동을 막는데 별 도움을 주지 못하나, 수착은 오염물질의 이동을 지연시키는데 상당한 효과가 있는 것으로 보인다.

• Proceedings of the Korean Radioactive Waste Society Conference
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• 2005.06a
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• pp.231-238
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• 2005

On the basis of flow resistance theory the conceptual model and related mathematical descriptions is proposed for resistance modeling of groundwater flow in CPM(continuum Porous medium), DFN(discrete fracture network) and fractured-porous medium. The proposed model is developed on the basis of finite volume method assuming steady-state, constant density groundwater flow. The basic approach of the method is to evaluate inter-block flow resistance values for a staggered grid arrangement, i.e. fluxes are stored at cell walls and scalars at cell centers. The balance of forces, i.e. the Darcy law, is utilized for each control volume centered around the point where the velocity component is stored. The transmissivity (or permeability) at the interface is assumed to be the harmonic average of neighboring blocks. Flow resistance theory was utilized to relate the fluxes between the grid blocks with residual pressures. The flow within porous medium is described by three dimensional equations and that within an individual fracture is described by a two dimensional equivalent of the flow equations for a porous medium. Newly proposed models would contribute to develop flow simulation techniques with various matrix characteristics.

• Economic and Environmental Geology
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• v.29 no.3
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• pp.325-333
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• 1996

numerical model is developed to estimate gas flow in the landfill site. Darcy's law, the mass conservation law, and the ideal gas state equation are combined to compose the governing equation for the steady-state and transient-state gas flows. The finite element method (FEM) is used as the numerical solution scheme. Two-dimensional radial symmetric triangular ring element is used to discretize the simulation domain. The steady state model developed in this study is compared with AIRFLOW that is a commercial model developed by Hydrologic Inc. Mass balance test is performed on the transient gas flow simulation. The developed model is applied to analyze the gas extraction experiment performed by Daewoo Institute of Construction Technology at the Nanjido landfill in 1993. The developed model was registered at Korea Computer Program Protection Foundation.

• Journal of the Korean Geotechnical Society
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• v.18 no.3
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• pp.105-112
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• 2002

Increases in excess pore water pressure without change of surcharge load were reported in clay underneath embankment at Berthierville and Olga sites after the end of construction. These abnormal phenomena could not be explained by classical consolidation theory. This paper presents a nonlinear viscoplastic model to interpret an increase in pore water pressure on natural clay, The proposed model can consider the combined processes of pore water pressure dissipation according to Darcy's law and pore water pressure generation due to viscoplastic strain, as well as time-dependent viscoplastic behaviour and strain rate dependency of preconsolidation pressure. The calculated results using numerical analysis are compared with measured ones under embankments built on soft clay at Berthierville and Olga in Quebec, Canada. It may be possible to explain the phenomenon of excess pore water pressure increase after the end of construction using the proposed nonlinear viscoplastic model.

• Proceedings of the Korea Water Resources Association Conference
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• 2015.05a
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• pp.82-82
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• 2015

해안 대수층은 해수와 담수가 공존하는 지역으로 상대적으로 밀도가 큰 해수가 대수층의 담수 아래에 쐐기형태로 존재하게 된다. 이러한 쐐기형태의 해수와 담수의 경계면은 압력경도의 평형에 의해 경계면이 유지되며, 해수면 또는 지하수위가 변동할 경우 해수-담수 경계면의 균형이 무너짐과 더불어 압력경도의 평행이 이루어질 때 까지 해수-담수 경계면의 이동이 계속 진행된다. 수위 변화의 주요 원인으로는 지구온난화 및 기후변화로 인한 지속적인 해수면 상승과 도서지역의 인구증가 및 산업화로 인한 무분별한 지하수의 사용 등에 의한 지하수위 저하 등을 꼽을 수 있다. 이와 같은 원인으로 해안 및 도서지역에서는 해안 대수층의 해수침투거리가 증가하여 지하수 이용에 큰 어려움을 겪고 있다. 이에 해안 대수층의 해수침투 범위 및 거리를 추정하기 위한 많은 연구들이 다양한 분야에서 지속해서 이루어지고 있지만, 서로 밀도가 다른 해수와 담수가 공존하는 해안 대수층 내의 수리특성을 명확히 파악하기에는 아직까지 미흡한 점들이 많다. 과거에는 Darcy의 법칙 및 Ghyben-Herzberg 식에 근거한 이론적인 연구들이 주로 이루어졌고, 근래에 현장관측이나 수리모형실험이 국내 외적으로 수행되고 있으나, 모든 영역의 지하수의 특성을 조사하는 것이 사실상 불가능하다. 이에 최근에는 컴퓨터 성능의 비약적인 발전과 더불어 다양한 수치해석방법에 의한 수치모델들이 개발되어 시뮬레이션에 적용되고 있다. 하지만 거의 대부분의 수치모델은 해안 대수층 수리특성을 투수계수에 의존하고 있을 뿐, 대수층 내부의 해수-담수에 의한 밀도류의 유동특성을 전혀 고려하지 못한 채 정수압에 근거한 해수-담수 경계면에 대해 모의하고 있는 정도이다. 따라서 본 연구에서는 해안 대수층 내부의 유동현상을 투수계수에 의존하는 방법에서 탈피하여 대수층 매체의 입경, 공극, 형상 등을 고려할 수 있을 뿐만 아니라, 염분 및 온도차에 의한 밀도류를 해석할 수 있는 강비선형 수치모델을 개발하여 해수침투 현상을 직접 모의한다. 나아가 대부분의 이전 연구들에서 간과하고 있는 해안지역의 대표적 물리력인 파랑과 조석의 영향이 해안 대수층의 해수침투에 미치는 영향, 해안 대수층의 지하수위 및 해수면의 수위차에 의한 해수침투 특성 그리고 이를 제어 할 수 있는 새로운 대응기술을 제안하는 것을 목적으로 한다.

• Journal of the Korea Society of Computer and Information
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• v.29 no.6
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• pp.23-29
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• 2024

In this paper, we propose a fast GPU-based method for representing pore flow, absorption, emission, and diffusion effects represented by cloth-liquid interactions using smoothed particle hydrodynamics (SPH), a particle-based fluid solver: 1) a unified framework for GPU-based representation of various physical effects represented by cloth-liquid interactions; 2) a method for efficiently calculating the saturation of a node based on SPH and transferring it to the surrounding porous particles; 3) a method for improving the stability based on Darcy's law to reliably calculate the direction of fluid absorption and release; 4) a method for controlling the amount of fluid absorbed by the porous particles according to the direction of flow; and finally, 5) a method for releasing the SPH particles without exceeding their maximum mass. The main advantage of the proposed method is that all computations are computed and run on the GPU, allowing us to quickly model porous materials, porous flows, absorption, reflection, diffusion, etc. represented by the interaction of cloth and fluid.

• Journal of the Korean Geotechnical Society
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• v.29 no.7
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• pp.75-89
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• 2013

This paper describes a GIS-based geohydrologic methodology, called YSGWF (YonSei GroundWater Flow) for predicting the rainfall infiltration-groundwater flow of slopes. This physical-based model was developed by the combination of modified Green-Ampt model that considers the unsaturated soil parameters and GIS-based raster model using Darcy's law that reflects the groundwater flow. In the model, raster data are used to simulate the three dimensional inclination of bedrock surface as actual topographic data, and the groundwater flow is governed by the slope. Also, soil profile is ideally subdivided into three zones, i.e., the wetting band zone, partially saturated zone, and fully saturated zone. In the wetting band and partially saturated zones the vertical infiltration of water (rainfall) from surface into ground is modeled. When the infiltrated water recharges into the fully saturated zone, the horizontal flow of groundwater is introduced. A comparison between the numerical calculation and real landslide data shows a reasonable agreement, which indicate that the model can be used to simulate real rainfall infiltration-groundwater flow.

• Journal of the Korean Society of Safety
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• v.11 no.4
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• pp.143-150
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• 1996

This is an explicit-Implicit, finite element analysis for linear as well as nonlinear hygrothermal stress problems. Additional features, such as moisture diffusion equation, crack element and virtual crack extension(VCE ) method for evaluating J-integral are implemented in this program. The Linear Elastic Fracture Mechanics(LEFM) Theory is employed to estimate the crack driving force under the transient condition for and existing crack. Pores in materials are assumed to be saturated with moisture in the liquid form at the room temperature, which may vaporize as the temperature increases. The vaporization effects on the crack driving force are also studied. The Ideal gas equation is employed to estimate the thermodynamic pressure due to vaporization at each time step after solving basic nodal values. A set of field equations governing the time dependent response of porous media are derived from balance laws based on the mixture theory Darcy's law Is assumed for the fluid flow through the porous media. Perzyna's viscoplastic model incorporating the Von-Mises yield criterion are implemented. The Green-Naghdi stress rate is used for the invariant of stress tensor under superposed rigid body motion. Isotropic elements are used for the spatial discretization and an iterative scheme based on the full newton-Raphson method is used for solving the nonlinear governing equations.

• Journal of Hydrogen and New Energy
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• v.30 no.6
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• pp.629-634
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• 2019

Dicyclopentadiene is a low viscosity resin which forms a poly-dicyclopentadiene rapidly through ring opening metathesis polymerization (ROMP). This poly-dicyclopentadiene has outstanding properties of low-temperature, water and impact resistances. Due to these advantages, military and offshore structures try to apply the DCPD composites by using liquid composite molding process. In this study, 14%, 38% volume fraction fiber glass strand mat reinforced p-DCPD composites processed by structural reaction injection molding (S-RIM) which has resin-catalsyt mixing head and glass fiber preform in the mold. Additionally, S-RIM numerical analysis was conducted to predict the process time depending on fiber volume fraction and mold temperature. The process time is shorter when it has the lower fiber volume fraction or the higher mold temperature. At higher mold temperature, it is necessary to set the maximum mold temperature considering the resin curing time.