• Journal of the Korea Concrete Institute
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• v.16 no.3 s.81
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• pp.397-406
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• 2004

A recently developed three dimensional concrete law is used for the analysis of concrete specimens and reinforced concrete columns subjected to different load patterns. The hypoelastic, orthotropic concrete constitutive model includes coupling between the deviatoric and volumetric stresses, works with both proportional and non-proportional loads and is implemented as a strain driven module. The FE implementation is based on the smeared crack approach with rotating cracks parallel to the principal strain directions. The concrete model is validated through correlated studies with: (a) experimental tests on confined concrete cylinders; (b) experimental results on three reinforced concrete columns tested at the University of California, San Diego. The correlations are overall very good, and the FE responses capture all the main phenomena observed in the experimental tests.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.14 no.3
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• pp.429-438
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• 1994

Three-dimensional analyses of multistory structures with wings using finite element models require tedious input data preparation, longer computation time. and larger computer memory. So this study lays emphasis on the development of efficient analysis models for a three-dimensional multistory structure with wings, including in-plane deformation of floor slabs. Since a three-dimensional multistory structure with wings is regarded as a combination of wing structures and their junction in this study, the proposed analysis models are easily applicable to multistory structures with plans in the shape of letters Y, U, H, etc. Dynamic analyses results obtained using proposed models are in excellent agreement to those acquired using three-dimensional finite element models in terms of natural vibration periods, mode shapes and displacement time history.

• Journal of the Korea institute for structural maintenance and inspection
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• v.14 no.6
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• pp.109-116
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• 2010

Three-dimensional finite element model for analysis of reinforced concrete members was developed in order to investigate the prediction of bending and shear failure of reinforced concrete beams. A failure surface of concrete in strain space was newly proposed in order to predict accurately the ductile response of concrete under multi-axial confining stresses. Cracking of concrete in triaxial state was incorporated with considering the tensile strain-softening behavior of cracked concrete as well as the cracked shear behavior on cracked surface of concrete caused by aggregate interlocking and, dowel action. By correlation study on failure types of bending and shear of beams, current finite element model was well simulated not only the type of ductile bending failure of under-reinforced beams but also the type of brittle shear failure of no-stirruped reinforced concrete beam.

• Journal of Energy Engineering
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• v.27 no.4
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• pp.13-19
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• 2018

In this study, the lightweight design of butterfly valve disc component for power plant based on topology optimization was performed. Here, commercial finite element (FE) analysis software was used. The external shape of the basic disc model was not deformed, and the internal element density was removed to make it lightweight. Optimal design was performed each other after the disc plate and two brackets attached on the surface of the disc were separated. Once the optimal shapes were selected, they were assembled to build up the 3-D lightweight valve disc model. After applying pressure to this model, FE analysis was performed to confirm the structural safety.

• Proceedings of the Korean Society for Bioinformatics Conference
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• 2004.11a
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• pp.57-63
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• 2004

본 연구에서는 3차원 심근조직에서의 회귀성파동에 대한 수치적 해석결과를 제시한다. 심근 조직에서의 회귀성파동은 심실세동(ventricular fibrillation)의 원인으로 지목되고 있으며 심근세포 이온채널 또는 전기전도시스템 등과 같은 여러 가지 요소들이 관련된 복합적 현상으로 생각되고 있다. 지금까지 이에 관한 많은 연구가 전기생리학적 모델을 이용하여 이루어진바 있으며, 주로 동물 심근세포모델에 기반으로 균일한 2차원 또는 3차원 모델에서의 전기전도 현상 해석을 한 바 있다. 그러나 실제 심장조직의 경우, 두께를 가진 3차원적 형상을 지니고 있으며 층을 따라서 전기생리학적으로 상이한 특성을 가진 세포들로 구성된다. 즉 심근은 층을 가로질러 Epi-cardiac, mid-cardiac, endo-cardiac cell들로 구성되며 각기 다른 APD(action potential duration)을 가지고 있다. 따라서 본 연구에서는 이러한 세가지 종류의 인체 심근세포모델을 사용한 3차원 심근조직에서의 활동전위 전도현상에 대한 결과를 제시한다. 이를 위하여 기존의 인체 3가지 종류의 심근세포 모델을 구현하여 그 타당성을 검토한다. 그리고 이를 바탕으로 3차원 조직모델을 구현하는데, simplified bidomain방법을 사용하였다. 3차원 공간상에서 심근세포에 의한 활동전위 전달현상을 해석하기 위하여 유한요소법을 도입한다. 최종적으로는 3가지의 심근세포층을 가진 3차원 심근조직을 구성하고, 여기에 회귀성 파동을 유도한다. 그리고 단일층으로 이루어진 3차원조직에서의 결과와 비교 분석하여 다세포층에 의한 불균일 효과를 분석하였다.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.10 no.9
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• pp.2183-2188
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• 2009

This paper describes an automatic mesh generation system for finite element analysis of three-dimensional cracks. It is consisting of fuzzy knowledge processing, bubble meshing and solid geometry modeler. This novel mesh generation process consists of three sub-processes: (a) definition of geometric model, i.e. analysis model, (b) generation of bubbles, and (c) generation of elements. One of commercial solid modelers is employed for three-dimensional crack structures. Bubble is generated if its distance from existing bubble points is similar to the bubble spacing function at the point. The bubble spacing function is well controlled by the fuzzy knowledge processing. The Delaunay method is introduced as a basic tool for element generation. Practical performances of the present system are demonstrated through several mesh generations for 3D cracks.

• Journal of the Korea Concrete Institute
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• v.25 no.5
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• pp.529-537
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• 2013

The aim of the current study is to develop a nonlinear isoparametric layered frame finite element (FE) analysis of FRP strengthened reinforced concrete (RC) beam or column members by a force-based FE formulation. In sections, concrete is modeled in the triaxial stress-strain relationship state and the FRP sheet is modeled as layered composite materials in two-dimension. The element stiffness matrix derived by the force-based FE has the force-interpolation functions without assuming the displacement shape functions. A lateral load test of RC column strengthened by GFRP sheets was analyzed by the developed force-based FE model. From comparative studies of the experimental and analysis results, it was shown to compare with the stiffness FE method that the force-based FE analysis could give more accurate predictions in the overall lateral load-deflection response as well as in nonlinear deformations and damages in the column plastic hinge region.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2011.04a
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• pp.579-582
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• 2011

본 논문에서는 9 % Ni강 LNG 저장탱크 조사를 통해서 유한요소해석을 수행하여 구조건전성을 평가하였으며 실용에서 활용할 수 있는 자료를 제시하였다. 과거의 LNG 저장탱크의 설계는 2차원 선에서만 유한요소해석이 수행되었으나 보다 진보된 하드웨어와 소프트웨어의 발전으로 3차원 유한요소해석이 가능케 되었다. 본 연구에서는 9 % Ni 강 LNG 저장탱크 내조의 정적 구조 해석이 상용 유한 요소 해석 프로그램인 ABAQUS를 통해 수행되었다. LNG 저장 탱크 내조 시공 시 용접부 형상을 참고하여 용접부 모델을 고려한 해석을 각각 수행하였다. 용접부의 탄성계수의 변화를 통하여 최대응력과 최대변위를 계산하였다. 실제 LNG tank의 운용 시 발생하는 하중은 자중과, 수두 압과, 온도차에 의한 열응력이며 이들이 복합적으로 작용하였을 시, 용접선을 고려하지 않은 모델에 대해서는 최대응력이 207 MPa이며, 동일 조건에서 용접선을 포함한 모델에 대해 해석을 수행한 결과로서 최대응력이 그보다 약 100 MPa 정도 상승한 결과가 나타났다. 하중조건에서 온도차에 의한 열응력을 고려함과 고려하지 않음을 비교함으로서 실제 열응력에 대해서는 내조에 큰 영향을 미치지 않음을 확인하였다.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.34 no.5
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• pp.339-345
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• 2021

Finite element analysis of the silo type underground opening for low- and intermediate-level radioactive waste (LILW) disposal facilities in Korea is presented in this study. The silo wall is circular and the roof is made up of domes. The silo wall is 25 meters in diameter, 35 meters in height, and the dome is 30 meters in diameter and 17.4 meters in height, and it is located at -80 meters to -130 meters at sea level. Although six silos have been constructed in the first stage and are in operation, only one silo was considered in this study. The two-dimensional axial symmetric finite element model, as well as the three-dimensional finite element model were made using the computer program SMAP-3D. Generalized Hoek and Brown Model was used for the numerical analyses. The finite element analysis of the silo type underground opening was carried out under various lateral pressure coefficients (defined as ratio of average horizontal to vertical in-situ stress), and the numerical results of these analyses were examined.

• Journal of Biomedical Engineering Research
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• v.8 no.1
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• pp.57-62
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• 1987

A three-dimensional thoracic model was constructed using 8-node trilinear hexahedron elements. A three-dimensional steady-state finite element code was developed using FORTRAN. Its output consists of potential at each node. current In each element, and total current In each layer in the z-direction. The thoracic model was Implemented to calculate basal impedance(Zo) In Impedance CardiograPhy Generalized Laplace's equation was solved with Dirlchlet(constant potentials) and homogeneous Neumann(no flux) boundary conditions. It was found that the con structed thoracic model was reasonable since the calculated potential differences between the adjacent electrodes and basal impedance were about the same as the measured ones.