• 한국가스학회지
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• 제12권4호
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• pp.8-13
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• 2008

전기철도의 궤도 누설전류는 주변 시설물 뿐 만 아니라 궤도 및 부속물의 전식을 일으킬 우려가 있다. 최근에는 누설전류의 영향을 감소시키기 위한 많은 노력이 기울여지고 있다. 본 연구에서는 수치해석 방법을 통하여 궤도와 매설배관의 이격거리, 토양비저항, 배관의 피복저항율, 궤도의 접지저항 등의 요인에 따른 간섭영향을 정량적으로 평가하였다. 이러한 정량적 연구결과를 토대로 주요 변수에 따른 간섭현상의 변화 방향을 예상할 수 있었으며 향후 대책의 수립과 수치해석에 있어서 각 변수의 민감도를 예상할 수 있었다.

• 대한기계학회논문집A
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• 제24권3호
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• pp.645-652
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• 2000

A method for shape design sensitivity analysis is proposed utilizing commercial software ANSYS for thermal conduction problems. While the sensitivity formula is derived analytically by introduing adjoint variable concept, sensitivity calculation in practice as well as the primal and adjoint solution of thermal conduction is performed using the ANSYS very easily. Since the formula always takes boundary integral form, sensitivity evaluation in ANSYS requires a little more addition of post-processing routine which involves evaluation of boundary variable from the obtained solution. Though the BEM has been used as a better tool for this purpose, the present study shows it can also be calculated using any kind of analysis code such as ANSYS since the formula is based on analytic nature. Therefore the present study provides a new and efficient way of optimization which was not possible before using commercial software. The usefulness of the method is illustrated via a weight minimization problem of thermal diffuser.

• 대한기계학회논문집A
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• 제30권2호
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• pp.149-156
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• 2006

A boundary-based design sensitivity analysis(DSA) technique is proposed for addressing shape optimization issues in the elastostatics problems. Sensitivity formula is derived based on the continuum formulation in a boundary integral form, which consists of the boundary solutions and shape variation vectors. Though the boundary element method(BEM) has been mainly used to obtain the boundary solution, the FEM is used in this paper because this is much more popular, and has greatly improved meshing and computing power recently. The advantage of the boundary DSA is that the shape variation vectors, which are also known as design velocity fields, are needed only on the boundary. Then, the step for determining the design velocity field over the whole domain, which was necessary in the domain-based DSA, is eliminated, making the process easy to implement and efficient. Problem of fillet design is chosen to illustrate the efficiency of the proposed method. Accuracy of the sensitivity is good with this method even by employing the free mesh for the FE analysis.

• 콘크리트학회지
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• 제8권6호
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• pp.205-212
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• 1996

본 논문은 경계요소법에 의한 콘크리트의 진행성 파괴해석과 연화거동 해석시 발생하는 불안정 거동을 규명하는 연구이다. 파괴가 일어나는 콘크리트에 작용하는 최대하중을 구하고 콘크리트의 균열 성장에 따른 비선형거동을 예측하기 위하여 균열선단의 브리징 영역에 Dugdale-Barenblatt형 모델을 사용하였으며, 브리징 영역의 인장연화 상태를 선형인장연화 곡선을 사용하여 모델링하였다. 경계요소법을 사용하였으며 콘크리트의 파괴진행을 해석하기 위하여 변위 및 표면력 경계적분방정식으로부터 균열을 포함한 연속체의 균열 경계적분방정식을 정식화하였으며, 콘크리트 보와 인장시편에 대하여 진행성 파괴해석을 실시하였다. 또한 콘크리트의 진행성 파괴해석에 자유응력균열의 성장 및 진행을 고려하지 않음으로서 발생하는 불안정 연화거동을 제거하는 수치해석기법을 제시하였다.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2009년도 추계학술대회 논문집
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• pp.110-112
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• 2009

Transient acoustic pressure in the near field of an impacted plate carries information that can be utilized for recovering the impact force history. The inverse calculation approach using BEM-based NAH, which is conventionally used for time harmonic excitation, can be applied for reconstructing the transient waves using the principle of Fourier transform and spectral analysis. Then, using the recovered velocity in normal direction of the plate surface, the corresponding structural intensity can be obtained and the identification of input power can be performed. However, several manipulations should be given to overcome numerical artifacts, such as aliasing and erratic oscillation at discontinuity, and to suppress the effect of noise. Experiment using a simply supported plate is presented for demonstration purpose.

• 대한기계학회논문집A
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• 제22권1호
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• pp.160-169
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• 1998

The purpose of this study for the prediction of fatigue crack propagation behavior, Stress Intensity Factor(F) of round bar with 3-Dimensional half circular, semi-elliptical icro surface crack under rotary bending stress for the variable aspect, size, rotation angle was analyzed by Boundary Element Method (BEM). It is predicted that behavior of crack growth is half circular or circular crack (b/a.geq.1) and propagate to b/a.leq.0.85.

• 대한조선학회논문집
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• 제47권3호
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• pp.369-376
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• 2010

In this study, a radiation and a diffraction problems of a floating body in two-layer fluids were solved by the Numerical Wave Tank(NWT) technique in the frequency domain. In two-layer fluids, two different wave modes exist and the hydrodynamic coefficients can be obtained separately for each mode. The two-domain Boundary Element Method(BEM) in the potential fluid using the whole-domain matrix scheme was used to investigate the characteristics of wave forces, added mass and damping coefficients. The effects of the ratio of density and water depth in the lower domain were also evaluated and compared with given references.

• 한국광학회:학술대회논문집
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• 한국광학회 1990년도 제5회 파동 및 레이저 학술발표회 5th Conference on Waves and lasers 논문집 - 한국광학회
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• pp.64-68
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• 1990

Boundary element method using linear basis function is applied to obtain fields scattered from a 3-D dielectric sphere. Electric field integral equation is used on the surfaces of the dielectric material where its surface is discretized into trilateral cells. For plane wave incidence, scattered fields by a dielectric sphere is calculated and compared with its analytic solution. The total electric fields are calculated on the great circle of the sphere boundary as well as the outside of the sphere in the plane of the wave vector and the polarization vector of the incident electric field.

• 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.

• 한국표면공학회지
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• 제28권5호
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• pp.309-319
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• 1995

The substrate patterned with the dry film has the cavity which has the $90^{\circ}$ wall angle. Electroplating Cu on this patterned substrate has the differrent shape history with the electrochemical parameters. By potential theory model, the reason of the variation of the shape change with the these parameters was investigated. The shape history could be explained by the current flow and the correlated area effects. By embedding the Ni layer between the Cu layers, shape history with the time was obtained experimentally and the results was compared with the numerical analysis by BEM. The adhesive Cr-Cu film in TAB application was etched with the various condition. The best condition for the etchant of the Cr-Cu film was found.