• 대한기계학회논문집A
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• 제21권4호
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• pp.673-678
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• 1997

Stress wave propagations in an elastic half space to a normal point force of ramp type in time are analyzed. The governing equations are transformed by applying the Laplace and Hankel transforms with respect to time and radial distance. The inversion of Laplace transforms are performed by employing the Cagniard-de Hoop method, where the Rayleigh waves at surface are obtained by including the residue terms. The stress waves computed at the location very cose to the surface are shown to be almost identical to the surface waves obtained by the residue method except the Rayleigh wavefront. It is found that at the surface, the stresses are dominated by the Rayleigh waves, whose amplitudes increase linearly with time when time is very large. It is also found that in the interior part, the radial stress has a logarithmic singularity at the shear wavefront, while tangential stress shows no singularity.

• 대한수학회보
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• 제52권4호
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• pp.1213-1223
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• 2015

We examine a family of isolated complex surface singularities whose exceptional curves consist of two complex curves with high genera intersecting transversally. Topological data of smoothings of these singularities are determined. We use these computations to construct symplectic 4-manifolds by replacing neighborhoods of the exceptional curves with smoothings of the singularities.

• 대한수학회보
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• 제60권1호
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• pp.113-122
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• 2023

We classify lens spaces with the Milnor fillable contact structure that admit minimal symplectic fillings whose second Betti numbers are one.

• 마이크로전자및패키징학회지
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• 제7권4호
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• pp.31-35
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• 2000

반도체 칩과 리드프레임을 접착하고 있는 얇은 접착제층에 전단하중이 가해질 때 발생하는 응력상태를 조사하고 있다. 계면 응력상태를 해석하기 위해서 경계요소법이 사용되고 있다. 선형 탄성이론을 적용하여 해석하면, 강체와 접착제의 계면이 자유 경 계면과 만나는 부분에서 $\gamma^{\lambda=1}$(0<1<1) 형태의 응력 특이성이 존재한다. 이러한 특이성으로 인해, 모서리 균열이나 계면 박리가 발생할 수 있다.

• 한국전산구조공학회:학술대회논문집
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• 한국전산구조공학회 2002년도 가을 학술발표회 논문집
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• pp.112-119
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• 2002

In this paper, an Extended Finite Element Method is proposed by adding discontinuity and singularity enrichment functions to the standard FEM approximation. In this method, the singularity and the discontinuity of the crack are efficiently modeled by using initial regular mesh without refining mesh near the crack tip, so that it enables express the asymptotic stress field near crack tip and crack surface successfully. The developed method was verified by evaluating crack tip stress profile and stress intensity factor of mode Ⅰ/mode Ⅱ fracture problems and the results showed the effectiveness and robustness for fracture problem.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1999년도 하계학술대회 논문집 A
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• pp.217-219
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• 1999

This paper presents a study of 2-dimensional(2-D) eddy current problem using boundary element method(BEM). When compared with finite element method(FEM), there are only a few unknown variables in BEM because it implements numerical analysis only for the surface or boundary of a model. As a result, a lot of computational memory and time can be saved. In order to analyze 2-D eddy current problem, potentials and its derivatives(flux) in a boundary are used as variables. The Mantel function of the second kind of the zero order is used here as a fundamental solution. In order to remove singularity and to solve the integral equations in a boundary, Subtracting Singularity Method and Gauss Quadrature Formula are adopted in this paper.

• 전산구조공학
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• 제10권1호
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• pp.129-134
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• 1997

탄성 섬유와 점탄성 기지로 구성된 2차원의 단일방향 복합재료에서 발생하는 계면 응력 특이성을 시간영역 경계요소법을 사용하여 조사하였다. 먼저, 아무런 균열없이 섬유와 기지가 완전하게 결합되어 있는 단일방향 복합재료에 횡방향 인장변형이 작용할때 자유경계면 부근에 나타나는 계면 특이응력들을 조사하였다. 그러한 응력들은 섬유와 기지의 결합분리나 계면 모서리 균열을 야기 시킬수 있다. 다음에, 여러가지 크기의 모서리 균열들에 대한 응력확대계수가 계산되었다.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2008년도 추계학술대회 논문집
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• pp.286-289
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• 2008

Mass of generator is one of the most important characteristic value especially direct drive type wind turbine. This paper introduce how to decease mass of generator rotor frame without declining generator performance. To obtain optimal design of rotor frame, sensitivity analysis using Taguchi method and RSM(response surface method) are have been performed.

• 대한조선학회논문집
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• 제28권2호
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• pp.104-117
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• 1991

자유표면을 가지는 유체에서 물체가 운동을 하게되면 물체와 자유표면의 교차점 주위에서 유제유동이 매우 급격해진다. 이 유동현상은 부유체의 운동에 따르는 유체유동, 탱크내에서의 슬로싱, 조파기 문제, 물체의 입수등 여러문제에서 발생된다. 이 유동은 교차점 주위에서 특이성을 가진다고 알려져 있었으나 Roberts(1987)는 물체의 운동이 충격운동이 아닐 경우에는 특이성이 존재하지 않는다는 것을 밝혔다. 본 논문에서는 표면장력을 고려하여 물체의 운동이 충격운동인 경우에도 특이성을 가지지 않는 해석해를 구하였고, 해의 특성을 조사하여 진동현상에 대한 임계치를 구하여 교차점에서 떨어진 거리가 이 임계치보다 작은 곳에서는 진동현상이 존재하지 않는다는 것을 밝혔다.

• Journal of Hydrospace Technology
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• 제2권2호
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• pp.36-43
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• 1996

In this work, a panel method is described, which cart solve the flow field round a surface-piercing body that experiences lift and wave resistance. As the body boundary condition, a Dirichlet type is employed, and as the free surface boundary condition the Poisson type is implemented, while in its discretization Dawson's 4-point upwind difference scheme is utilized, and as the Kutta condition a Morino-Kuo type is chosen. As to the type of singularity, source panels are distributed on the free surface, and source and dipole panels on the body surface, and dipole panels on the wake surface. For a sample run, a catamaran of the parabolic Wigley hull is chosen, for which experimental data are available, and the predictions by the numerical means and by the experiment are compared for a wide range of parameters.