• Geotechnical Engineering
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• v.12 no.5
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• pp.27-40
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• 1996

Box culvert has long since been used for various purposes , water and sewerage works, communication and electricity facilities, subway, railway, etc. In urban area, the construetion of box culvert generally consists of excavation-installation of the culvert-backfill. However, the existing design methods for earth pressure on the box culvert do not take into account the excavation(or backfill) geometry. ' A new method considering excavation geometry for earth pressure on box culvert is suggested here. The lateral earth pressures by the newly suggested method agree relatively with results of finite element analyses, but those of existing method are greatly overestimated. The vertical pressure on the top of the box culvert by the new method is similar to those of existing method and finite element analysis. However, the reactional pressure on the bottom of the box culvert depends largely upon the stiffness of the foundation soil. The reactional pressure by the new method agrees well with that of finite element analysis, only when the stiffness is low. From the finite element analysis it is shown that the lateral earth pressure on box culvert depends upon the excavated slope (G) and the net bottom distance (Bc).

• Computational Structural Engineering
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• v.1 no.2
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• pp.83-90
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• 1988

The present work is concerned with the improvement of finite element for the analysis of plate bending structures. The element formulation is based upon Mindlin plate concept. The displacement field of this element is formed by adding nonconforming modes to two rotational displacement components of a 'heterosis plate element. The element has the requisite numbers of zero eigenvalues associated with rigid body modes to avoid the spurious zero energy mode. It is shown that the results obtained by the element converged to the exact solutions very rapidly as the mesh is refined and exhibited reliable solutions through numerical studies for standard benchmark problems. This element is shown to overcome the shear locking problem completely in very thin plate situation even for irregular meshes.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.12 no.2
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• pp.141-148
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• 1999

변위 근거 유한요소해석을 사용하는 대부분의 위상 최적화 기법은 요소의 안정성 부족으로 인하여 체스판 무늬가 주기적 형태로 반복하여 설계영역 내부에 나타난다. 본 연구에서는 선형요소를 이용하면서 최적화 알고리즘의 안정성에 영향을 주지 않고 간단하게 모든 최적화 알고리즘에 이용 가능한 체스판무늬 형성 방지책을 개발하였다. 본 연구의 체스판무늬 형성 방치책에서는 먼저 각 선형요소를 구성하는 절점들의 부치분율을 설계변수로 선정하고, 요소내부의 부피분율을 설계변수로 표현하기 위한 선형 보간함수로 선형요소들의 형상함수를 선정하였다. 그리고, 설계변수와 등가 재료상수와의 상관 관계식은 평균장 근사이론을 이용하여 균질화된 재료에 벌칙인자가 도입된 관계식을 이용하였다. 또한, 본 연구에서는 순차이차계획법인 PLBA 알고리즘을 이용하여 위상 최적화문제를 해석하였다.

• Journal of Korean Association for Spatial Structures
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• v.8 no.5
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• pp.95-105
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• 2008

The objective of this study is find out the stressed condition, slipped direction and slipped dimension when some elements of cable-membrane structures are slipped from it's initially designed coordinates by external loads as wind or non uniform load and so on. In order to search the slipped behaviors of cable-membrane structures, a ALE finite element formulation is introduced. In these procedures, a stiffness matrix related with ALE concept is formulated and a FE analysis program for cable-membrane structures with slipped elements is developed.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.16 no.1
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• pp.95-104
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• 2003

This paper deals with the analytic and FEM analyses of sloshing frequency response of incompressible, invicid and irrotational flow in two dimensional rectangular tank. We use Laplace equation based on potential theory as governing equation. For small amplitude sloshing motion, the linearized free surface condition was applied and the analytic solution as obtained by the separation of variables. To simulate the effect of the energy dissipation due to viscous damping, artificial viscous coefficient is introduced and the divergence of response at resonance frequencies may be avoided by this coefficient. This problem was solved by FEM using 9-node elements in order to predict the maximum amplitude of sloshing response. Numerical results of free surface height, fluid pressure and fluid force show good agreement with those by analytic solution. After verifying the test FEM program, we analyze the frequency response characteristics of sloshing to the fluid height.

• Journal of the Korean Geotechnical Society
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• v.36 no.12
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• pp.27-34
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• 2020

Use of axisymmetric shell element for the structure increases the efficiency and accuracy in finite element analysis of the interaction between the ground and the structure. This paper derived the force balance equation and the moment balance equation for an axisymmetric shell element based on Kirchhoff's theory. The governing equation for the axial deformation used the isoparametric shape function in the Galerkin formulation, and the governing equation for the shell bending used the higher-order shape function. The developed axisymmetric shell element was combined with Geo-COUS, a geotechnical finite element program for the coupled analysis with the ground. The accuracy of the developed element was confirmed through the example analyses of the circular plate and the liquid storage tank. And the energy balance equation for the axisymmetric shell element is presented.

• Proceedings of the KAIS Fall Conference
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• 2002.11a
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• pp.149-151
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• 2002

본 논문에서는 유한요소를 자동으로 생성하는 프로그램을 구현하였다. Delaunay 삼각화이론을 적용하여 요소를 생성하였고 요소의 생성 속도를 개선하기 위해서 로손(Laswson)의 찾기 알고리즘을 적용하였다. 요소의 형상을 개선하고자 절점들을 효과적으로 배치하고 분할 한 후에 라플라스 조정을 통해 등변에 가까운 요소로 생성하였다. 본 논문에서 제시한 알고리즘의 검증을 위해 박막층을 가진 초고주파 소자를 선택하여 요소의 형상과 생성과정에서 검색회수를 비교하였다.

• Composites Research
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• v.16 no.4
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• pp.1-9
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• 2003

2 ply laminated composite is regarded to simulate the interply behavior of the belt layer of the tire. It was cone with 3 dimensional FE(Finite Element) analysis to determine interply shear stress and strain. Widthwise, the shear strain was measured by the pin method. These results are compared with those of CLT(classical lamination theory) in center region and those of Kassapoglou's and Kelsey's theory in edge region. In the FE analysis. rubber is assumed as linear elastic material. and rubber/cord laminate as the orthotropic material composed of cord and rubber In the FE result, interlaminar shear stress causing the interlaminar delamination has the largest value in the edge region of the inner rubber layer. Numerical results obtained coincides with CLT well in the center region, and agrees with other theoretical result little in the edge region.

• Computational Structural Engineering
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• v.8 no.3
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• pp.59-66
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• 1995

The dynamic responses of structure under impulsive loading have been investigated according to its duration, based on the theory of viscoplasticity which can appropriately represent the effects of plasticity and rheology simultaneously. The viscoplastic model has been implemented into the two-dimensional finite element system to solve plane stress, plane strain or axi-symmetric problems, and the implicit integration scheme, of which solutions are unconditionally stable for relatively large time step length, has been developed to simulate visoplastic straining with deriving the explicit relationship between stress and strain at a material point level. After simulation, one carefully concludes that the duration as well as magnitude of impulsive loading plays an important role in design of structures.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2009.04a
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• pp.283-286
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• 2009

척추경 나사못을 이용한 요추 유합술은 가장 보편적으로 사용되어지는 수술적 치료 방법이다. 과거 여러 연구들에서 이러한 척추 유합술의 임상적 우수성은 이미 입증 되었으며, 척추경 나사못은 시술 부위의 운동을 완전히 제한함으로써 높은 유합율을 얻을 수 있으나, 상대적으로 인접 분절의 조기 퇴행성 변화의 요인 중 하나로 보고되고 있다. 따라서 본 연구에서는 유한요소해석 방법을 이용하여 척추경 나사못 시술에 따른 척추체의 운동범위 및 인접 분절 추간판의 스트레스 증가량을 계산하였고, 척추경 나사못 모델과 유합 후 나사못 제거에 따른 모델 또 시술하기 전 정상모델과 비교하여 생체 역학적 측면에서 분석하여 척추경 나사못을 이용한 요추 유합술 후, 척추경 나사못의 제거의 임상적 효과와 그 이론적 근거를 제시하고자 한다.