• KSCE Journal of Civil and Environmental Engineering Research
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• v.5 no.4
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• pp.9-14
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• 1985

In this research mass of a plane strain two dimensional elastic concrete dam under gravitational and hydrostatic loads is minimized, through shape optimization of the dam cross section. Cross sectional area of the dam is taken as cost function of the optimization problem while constraints on the principal stress distribution and dam thickness are imposed. Shape of the boundary of the model is chosen as design variable. Variational formulation of the optimization problem, the material derivative idea of continuum mechanics, and an adjoint variable method are employed for the shape design sensitivity calculation. Then the gradient projection algorithm is utilized to obtain an optimum design iteratively. Research results fully demonstrate that the theory and procedure adopted are quite efficient and can be applicable to a wide class of practical elastic structural design problems.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.20 no.3
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• pp.321-327
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• 2007

This study presents a new gridless finite difference method for solving elastic crack problems. The method constructs the Taylor expansion based on the MLS(Moving Least Squares) method and effectively calculates the approximation and its derivatives without differentiation process. Since no connectivity between nodes is required, the modeling of discontinuity embedded in the domain is very convenient and discontinuity effect due to crack is naturally implemented in the construction of difference equations. Direct discretization of the governing partial differential equations makes solution process faster than other numerical schemes using numerical integration. Numerical results for mode I and II crack problems demonstrates that the proposed method accurately and efficiently evaluates the stress intensity factors.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.24 no.2
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• pp.121-131
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• 2011

An object oriented programming(OOP) framework is presented to solve plane elastostatic contact problems by means of the boundary element method(BEM). Unified modeling language(UML) is chosen to describe the structure of the program without loss of generality, even though all implemented codes are written with C++. The implementation is based on computational abstractions of both mathematical and physical concepts associated with contact mechanics involving geometrical nonlinearities and the corner node problems for multi-valued traction. The overall class organization for contact analysis is discussed in detail. Numerical examples are also presented to verify the accuracy of the developed BEM program.

• Computational Structural Engineering
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• v.11 no.1
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• pp.227-235
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• 1998

A method of calculating the natural frequency corresponding to the first mode of vibration of beams and tower structures, with irregular cross-sections and with arbitrary boundary conditions was developed and reported by D. H. Kim in 1974. This method has been developed for two-dimensional problems including the laminated composite plates and was proved to be very effective for the plates with arbitrary boundary conditions and irregular sections. In this paper, the result of application of this method to the building slabs with passive and active control devices is presented. Finite difference method is used to obtain the deflection influence surfaces needed for this vibration analysis in this paper. The influence of the modulus of the foundation on the natural frequency is thoroughly studied.

• Bulletin of the Society of Naval Architects of Korea
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• v.27 no.3
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• pp.107-116
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• 1990

The liquid sloshing in an elastic tank is a fluid-structure interaction problem. It requires nonlinear analysis to solve the complicated physics involved in the large interaction of fluid-structure, the variation of dynamic characteristics of structure due to hydrodynamic loading, and the distorsion of fluid flow due to structural vibration. In this paper a Lagrangian FEM is introduced to analyze the liquid sloshing in an elastic tank assuming that the elastic wall is one degree of freedom rigid wall. Numerical integration is performed using an implicit-explicit algorithm, which is formed by mixing the predictor-corrector method and the Runge-Kutta 4th order method. The influence of dynamic characteristics of the sloshing tank on the fluid flow is discussed. The numerical method is also applied for the simulation of the wall generated wave in the tank.

• Journal of the KSME
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• v.25 no.1
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• pp.39-46
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• 1985

동적 탄성 파괴역학 문제들을 실험적으로 연구하기 위해서는 우선 빠르게 전파하고 있는 균열 선단(전파속도 V=100m/sec∼1000m/sec for various polymers) 부근의 응력분포 상태나 변위분포 상태등을 기록하는 실험장치가 필수적으로 필요하다. 먼저 Wells와 Post(7)에 의하여 처음으로 사용되었고 Kobayashi(18,19,20)와 Dally(21)등에 의해서 발전, 개선된 동적 광탄성 실험범에 대 하여 설명하고 이 실험에 의하여 동적 응력확대계수를 추출하는 방법을 아울러 강의하고 그의 문제점 등을 논의 하고자 한다.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2002.05a
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• pp.1116-1119
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• 2002

최근의 국제화 추세에 따라 국내의 산업규격을 국제규격인 ISO와 부합시키는 방향으로 나아가고 있다. 공동주택의 바닥충격음 문제가 사회적인 관심이 되면서 탄성재료(완충재)를 이용한 뜬 바닥 구조가 많이 사용되고 있다. 탄성재료의 동탄성계수와 바닥충격음의 경량충격음과는 밀접한 관계가 있다.(중략)

• Proceedings of the Computational Structural Engineering Institute Conference
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• 1996.04a
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• pp.87-94
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• 1996

The stress intensity factor for an inter(ace crack in dissimilar elastic-elastic bimaterials is presented and the boundary element analysis is performed. It is shown that the proposed method produces the accurate and effective numerical results.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.12 no.3
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• pp.485-494
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• 1999

본 연구에서는 요소를 사용하지 않고 절점들만을 이용하여 해석이 가능한 새로운 수치해석기법인 EFG(Element-Free Galerkin)법을 사용하여 임의의 균열의 성장과정을 해석할 수 있는 효율적인 알고리즘을 개발하고, 이를 바탕으로 균열의 성장방향과 경로를 정확히 추정하여 일련의 균열진전해석을 수행할 수 있는 프로그램을 개발하였다. 균열해석에 있어서는 균열선단의 특이성과 균열면의 분연속성을 수치적으로 반영할 수 있는 기법을 도입하여 균열을 모형화하였으며, 선형탄성파괴역학이론에 근거하여 균열해석과정을 정식화하였다. 또한, EFG 형상함수가 kronecker delta 조건을 만족시키지 못함으로써 발생하는 필수경계조건의 처리문제를 penalty법을 이용하여 해결하였다. 개발된 균열진전해석 알고리즘을 정지상태와 성장하는 상태에 있는 모드 Ⅰ, 모드 Ⅱ 및 혼합모드상태의 대표적인 균열문제들에 적용하여 응력확대계수와 균열성장방향 및 균열의 성장경로를 추정하고 이를 이론적·실험적 결과들과 비교함으로써 그 정확성과 효율성을 검증하였다.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.20 no.4
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• pp.501-507
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• 2007

In the first part of this study, the moving least squares finite difference method for solving solid mechanics problems was formulated. This second part verified the accuracy, robustness and effectiveness of the developed method through several numerical examples. It was shown that the method gives excellent convergence rate for elasticity problem. The solution process of elastic crack problems showed the easiness in discontinuity modeling and demonstrates the accuracy and efficiency in finding singular stress solution based on adaptive node distribution. The applicability to the engineering problem with abrupt change in displacement and stresses gradient fields is verified through a localization band problem. The developed method is expected to be extended to the various special engineering problems.