• Journal of the Computational Structural Engineering Institute of Korea
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• v.23 no.4
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• pp.361-368
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• 2010

In this paper, the parallel algorithm using MPI(Message-Passing Interface) library is introduced in order to improve numerical efficiency for the staggered method for nearly incompressible and impermeable porous media which was introduced by Park and Tak(2010). The porous media theory and the staggered method are also briefly introduced in this paper. Moreover, we account for MPI library for blocking, non-blocking, and collective communication, and propose combined the staggered method with the blocking and nonblocking MPI library. And then, we present how to allocate CPUs on the staggered method and the MPI library, which is related with the numerical efficiency in order to solve unknown variables on nearly incompressible and impermeable porous media. Finally, the results comparing serial solution with parallel solution are verified by 2 dimensional saturated porous model according to the number of FEM meshes.

• Computational Structural Engineering
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• v.3 no.1
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• pp.11-14
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• 1990

전자문명의 혜택으로 정보수록매체가 종이에서 플로피디스크나 하드디스크로 바뀌게 되었다. 그러나 이렇게 전자로 수록된 엔지니어링 정보를 관리하는 일도 여간 복잡한 일이 아니다. 최근 선두 CAD 소프트웨어 개발업체와 프로젝트 관리 소프트웨어 개발업체가 한 팀이 되어 엔지니어링 데이타의 자동관리 시스템을 개발하였다. 제조업체에서는 Computer Aided Engineering을 도입함으로써 설계자나 제도사 또는 생산라인에 있는 작업자를 도와 대단히 성공적으로 생산성을 향상시킨 사례들을 보고하고 있다.

• Communications of the Korean Institute of Information Scientists and Engineers
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• v.22 no.8
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• pp.41-49
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• 2004

올해 우리나라의 인터넷 이용자 수가 3,000만 시대에 접어들었으며 수능 e-learning교육 시장이 2000억원 대 수준이 될 것이라는 한국전산원의 전망이 발표되었다 (1). 이런 수치적인 인터넷 시장 전망이 우리에게 의미하는 것은 무엇인가？ 우리나라에서의 인터넷이라는 것은 소수 집단의 점유물이 아닌 일반인들에게 친숙하게 다가가 있는 생활의 한 매체가 되어 버린 것이다.

• 한국전산유체공학회:학술대회논문집
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• 2007.10a
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• pp.249-257
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• 2007

A high resolution numerical method aimed at solving gas-liquid two-phase flow is proposed and applied to gas-liquid two-phase shock tube problem. The present method employs a finite-difference 4th-order Runge-Kutta method and Roe's flux difference splitting approximation with the MUSCL TVD scheme. By applying the homogeneous equilibrium cavitation model, the present density-based numerical method permits simple treatment of the whole gas-liquid two-phase flow field, including wave propagation and large density changes. The speed of sound for gas-liquid two-phase media is derived on the basis of thermodynamic relations and compared with that by eigenvalues. By this method, a Riemann problem for Euler equations of one dimensional shock tube was computed. Numerical results such as detailed observations of shock and expansion wave propagations through the gas-liquid two-phase media and some data related to computational efficiency are made. Comparisons of predicted results and exact solutions are provided and discussed.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.23 no.4
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• pp.369-378
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• 2010

The mixed finite element analysis is the most widely used method for saturated porous media. Generally, in this method, direct method and iterative method are proposed to obtain unknown variable, however, the iterative method is recommended because the method provide numerical stability and accuracy under the material properties for solid and fluid are different. In this paper, we introduce staggered method which has strong numerical stability, and FETI(Finite Element Tearing and Interconnecting) which is one of decomposition methods are applied into the method in order to obtain numerical efficiency. In which, Lagrange Multipliers and conjugated gradient method to solve decomposed domain are proposed, and then, the proposed method is verified numerical efficiency by point to point MPI(Message Passing Interface) library.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2008.04a
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• pp.20-25
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• 2008

The finite element analysis for porous media is severe job because constituents have different physical peoperties, and element's continuity and stability should be considered. Thus, we propose the new mixed finite element method in order to overcome the problems. In this method, multi time step, remeshing step, and sub iteration step are introduced. The multi time step and remeshing step make it possible to satisfy a stability and an accuracy during sub iteration in which global time is determined. Finally, the proposed method is compared with the ABAQUS(2007) software and exact solution(Schiffman 1967) through two dimensional consolidation model.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2003.04a
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• pp.235-242
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• 2003

The solids and the fluids in porous media have a relative velocity to each other. Due to physically and chemically different material properties and their relative velocity, the behavior of saturated porous media is extremely complicated. Thus, in order to describe and clarify the deformation behavior of saturated porous media, constitutive models for deformation of porous media coupling several effects such as flow of the fluids or thermodynanical change need to be developed in frame of Arbitrary Lagrangian Eulerian (ALE) description. The aim of ALE formulations is to maximize the advantages of Lagrangian and Eulerian elements, and to minimize the disadvantages. Therefore, this method is appropriate for the analysis of porous media that are considered for the behavior of the solids and the fluids. In this work, governing equations of porous media based on ALE description are obtained from governing equations in frame of updated Lagrangian description. Then, weak forms of these equations are derived using arbitrary weighting functions.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2006.04a
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• pp.381-388
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• 2006

A porous medium is composed of solids, fluids, and gas which have different physical and chemical properties. In addition, these constituents have a relative velocity between each other. So far, in order to analyze porous media using finite element method, Lagrangian or Eulerian method has been used. However, the numerical analyses for porous media have a defect that the methods do not describe the movements of constituents. In this paper, numerical analysis for unsaturated porous media was performed in frame of ALE method which has advantages of Lagrangian and Eulerian. Namely, the Lagrangian description was used in solid phase, and the Eulerian description was used in fluid or gas phase in a porous medium Then the relationship between each other was controlled by the convective term in ALE method. Finally, the numerical results of ALE were compared with tile results of Lagrangian analysis.

• 한국전산유체공학회:학술대회논문집
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• 2011.05a
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• pp.46-53
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• 2011

Water is continuously produced in polymer electrolyte membrane fuel cell (PEMFC), and is transported and exhausted through polymer electrolyte membrane (PEM), catalyst layer (CL), microporous layer (MPL), and gas diffusion layer (GDL). The low operation temperatures of PEMFC lead to the condensation of water, and the condensed water hinders the transport of reactants in porous layers (MPL and GDL). Thus, water flooding is currently one of hot issues that should be solved to achieve higher performance of PEMFC. This research aims to study liquid water transport in porous layers of PEMFC by using pore-network model, while the microscale pore structure and hydrophilic/hydrophobic surface properties of GDL and MPL were fully considered.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2011.04a
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• pp.441-444
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• 2011

최근 IT분야의 눈부신 발전으로 Web 3.0의 시대를 맞아 유비쿼터스 시대에 점점 다가가고 있다. 그리하여, 일반 이용자도 전문 기술자들의 지식을 인터넷이나 스마트 폰과 같은 통신매체를 통해 쉽게 습득 할 수 있게 되어, 측량과 같은 전문적인 분야도 일반 사용자가 원할 때는 언제, 어디서나 사용할 수 있도록 하기 위해 연구를 진행 하였다. 본 논문의 목적은 전파를 통해 언제, 어디서나, 누구나 지식을 요하지 않아도 정적, 동적 객체 위치 개념의 정보, 해석, 관리 등을 할 수 있는 무선 측위 네트워크를 구축하기 위해, 실내에 무선 네트워크 망을 구성하여, 1차원 또는 2차원, 장애물 투과성, 이동 객체 대상물의 측위를 통하여, U-Surveying을 위한 기초 실험을 하였다.