• 한국해양공학회지
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• 제11권1호
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• pp.3-9
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• 1997

In this paper, design sensivity of plate natural frequency is computed for thickness design variables. Once the variational equation is derived from Lagrange quation using the virtual displacement, governing energy bilinear form is obtained and sensivity equation is formulated through the first variation. Natural frequency is obtained using the commercial FEM code and the accuracy of sensivity is verified by finite difference. The accuracy of natural frequency and sensivity improves for the fine mesh model.

• 한국농공학회지
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• 제36권1호
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• pp.83-94
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• 1994

The first part of this study dealt with the determination of soil parameters for Lade's double work-hardening model using the raw data obtained from cubical and cylinderal triaxial tests At present, it should be investigated which test can simulated satisfactorily the behavior of soft clayey foundation. In this regard, plate bearing test on the 2-dimentional model foundation(218cm long, 40cm wide, 19&m high) was performed, and finite element analysis carried out to abtain the behavior of the foundation. Settlement, lateral displacement, displacement vector and mode of failure were measured and these values were compared with numerical values in order to validate the numerical program developed by authors. The FEM technique was based on Christain-Boehmer's method, in which the displacement is obtained at each nodal point while stress and pore water pressure at each element.In this research, Biot's equation, which explains was elahorately the phisical meaning of consolidation, was selected, as a governing equation, coupled with Lade's double surface work-hardening constitutive model.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1989년도 추계학술대회 논문집 학회본부
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• pp.211-215
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• 1989

This paper presents the thermal analysis of EHV OF cable accessories using FEM. The governing equation about the temperature in the cable accessories is induced by the energy balance equation. Since the temperature distribution is a function of space and time, the weighted residual method is adopted for FEM formulation. The difference approximation is used to treat the time differential term in the element equation. Automatic mesh generation which save time and labor is introduced for the data input process. It will be expected that the following thermal analysis result will be very useful to cable accessories design.

• 한국전산구조공학회논문집
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• 제16권2호
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• pp.125-131
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• 2003

본 논문에서는 중고주파수 영역에서 진동하는 단순평판의 진동을 해석하기 위하여 파워흐름유한요소법을 적용하였다. 파워흐름해석법에서 주어지는 진동 에너지지배방정식의 해를 구하기 위한 수치해석 도구로써 유한요소법을 활용하였다. 이러한 파워흐름유한요소법을 적용하여 중고주파수 영역에서 진동하는 단순평판의 진동 변위와 진동인텐시티 분포를 구하였다. 또한 수치해 결과를 엄밀해와 유한요소법에 의한 근사해와 비교함으로써, 파워흐름유한요소법은 중고주파수 영역에서 진동 변위 및 진동 인텐시티를 예측하기 위하여 효과적으로 적용될 수 있음을 보였다.

• Structural Engineering and Mechanics
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• 제43권5호
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• pp.561-582
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• 2012

Despite popularity of FEM in analysis of static and dynamic structural problems and the routine applicability of FE softwares, analytical methods based on simple mathematical relations is still largely sought by many researchers and practicing engineers around the world. Development of such analytical methods for analysis of free vibration of non-prismatic beams is also of primary concern. In this paper a new and simple method is proposed for determination of vibration frequencies of non-prismatic beams under variable axial forces. The governing differential equation is first obtained and, according to a harmonic vibration, is converted into a single variable equation in terms of location. Through repetitive integrations, integral equation for the weak form of governing equation is derived. The integration constants are determined using the boundary conditions applied to the problem. The mode shape functions are approximated by a power series. Substitution of the power series into the integral equation transforms it into a system of linear algebraic equations. Natural frequencies are determined using a non-trivial solution for system of equations. Presented method is formulated for beams having various end conditions and is extended for determination of the buckling load of non-prismatic beams. The efficiency and convergence rate of the current approach are investigated through comparison of the numerical results obtained to those obtained using available finite element software.

• 전기전자학회논문지
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• 제23권3호
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• pp.793-799
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• 2019

본 연구에서는 웨어러블 Fabric(Nylon) + MWCNT 가스센서 내부에서 열확산을 해석하기 위해서 요소해석 프로그램(comsol)을 이용하여 센서 내부에서의 열용량의 확산 과정과 열용량 분포 경도를 확인하였다. 열용량의 확산과정을 해석하기 위해서 가스센서의 구조체에 대하여 이차원으로 모델링을 진행하였으며, 제시된 모델링에 대해서 센서 구성 부분에 대한 특성값을 제시하여 메시 요소법(FEM)을 이용하여 설계된 웨어러블 가스센서에 대해서 열용량이 확산되는 정도와 열용량 경도를 구하기 위해서 지배방정식으로 1계 편미분방정식을 제안하여 해석하였으며, 열속도 전달식을 제안하여 전극층과 가스 검출부의 10[K/mm] 온도 경도를 구하였다.

• 한국지반공학회논문집
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• 제36권12호
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• pp.27-34
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• 2020

구조물에 대한 축대칭 쉘요소는 지반과 구조물의 상호작용에 대한 유한요소해석에서 효율성과 정확성을 높이게 된다. 본 논문에서는 Kirchhoff 이론에 근거한 축대칭 쉘요소의 힘평형 방정식과 모멘트 평형 방정식을 유도하였다. 축방향 변형에 대한 지배방정식은 등매개변수 형상함수를 이용한 Galerkin 수식화를 수행하고, 휨에 대한 지배방정식은 고차의 형상함수를 이용하였다. 개발된 축대칭 쉘요소는 지반과의 연계해석을 위하여 지반해석 유한요소 프로그램인 Geo-COUS에 결합하였다. 원형판과 액체 저장 탱크에 대한 예제해석을 통하여 개발된 요소의 정확성을 확인하였다. 그리고 축대칭 쉘요소에 대한 에너지 평형방정식을 제시하였다.

• 대한기계학회논문집
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• 제18권8호
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• pp.2113-2122
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• 1994

The 3-D FEM analysis for simulating the stamping operation of planar anisotropic sheet metals with arbitrarily-shaped tools is introduced. An implicit, incremental, updated Lagrangian formulation with a rigid-viscoplastic constitutive equation is employed. Contact and friction are considered through the mesh-normal, which compatibly describes arbitrary tool surfaces and FEM meshes without depending on the explicit spatial derivatives of tool surfaces. The consistent full set of governing relations, comprising equilibrium equation and mesh-normal geometric constraints, is appropriately linearized. The linear triangular elements are used for depicting the formed sheet, based on membrane approximation. Barlat's non-quadratic anisotropic yield criterion(strain-rate potential) is employed, whose in-plane anisotropic properties are taken into account with anisotropic coefficients and non-quadratic function parameter. The planar anisotropic finite element formulation is tested with the numerical simulations of the stamping of an automotive hood inner panel and the drawing of a hemispherical punch. The in-plane anisotropic effects on the formability of both mild steel and aluminum alloy sheet metals are examined.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2010년도 추계 학술발표회
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• pp.808-812
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• 2010

A great deal of attention is focused on coupled Thermo-Hydro-Mechanical (THM) behavior of multiphase porous media in diverse geo-mechanical and geo-environmental areas. This paper presents general governing equations for coupled THM processes in unsaturated porous media. Coupled partial differential equations are derived from 3 mass balances equations (solid, water, and air), energy balance equation, and force equilibrium equation. Finite element code is developed from the Galerkin formulation and time integration of these governing equations for 4 main variables (displacement $\underline{u}$, gas pressure $P_g$, liquid pressure $P_l$), and temperature T). The code is validated with theoretical solutions for linear material with simple boundary conditions.

• 한국지진공학회:학술대회논문집
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• 한국지진공학회 1998년도 춘계 학술발표회 논문집 Proceedings of EESK Conference-Spring 1998
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• pp.98-105
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• 1998

In this study, the boundary element analysis in dynamics for the multilayered semi-infinite plane is developed using the fundamental solution for moving loads. Also the indirect method and superposition method are introduced to consider the multilayered systems and moving loads. At each layer the fundamental solution can be obtained by solving the governing equation which is transformed by the Fourier transform. The governing equation can be solved by three conditions; continuity conditions of displacement and stress, the traction free condition at the surface and the radiation condition at the surface and the radiation condition at the infinite distance. To verify the solution and the developed algorithm, the theoretical solution for the homogeneous layer and commercial FEM program is compared with the results of this study.