• 대한기계학회:학술대회논문집
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• 대한기계학회 2003년도 춘계학술대회
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• pp.346-351
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• 2003

In this paper, an evaluation method of fracture toughness on interface cracks has been investigated under various mixed-mode conditions of the bonded scarf joints. Two types of the bonded scarf joints with an interface crack were prepared to analyze the stress intensity factors using boundary element method(BEM) and to perform the fracture toughness test. From the results of fracture toughness experiments and BEM analysis, an evaluation method of fracture toughness on interface cracks in the bonded components of dissimilar materials has been proposed and discussed.

• 대한기계학회논문집A
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• 제32권9호
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• pp.713-719
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• 2008

Most of the MEMS parts are made of multi-grain silicon wafer, which is the orthotropic material and its material direction is arbitrary. The reliability of the parts must be guaranteed in order to use for the commercial usage. The need of the structural analysis of its parts emerges an important factor. The material properties of the MEMS parts are calculated by the numerical method in order to reduce a material test. In this study, the effective elastic modulus and its Poisson's ratio are calculated by the boundary element method(BEM) and are compared with the results by the finite element method(FEM).

• 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.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1993년도 하계학술대회 논문집 B
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• pp.1007-1009
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• 1993

In this paper, The hybrid method in order to reduce the unknown varible for 3D eddy current calculation is proposed. we adopt the current vector potential(T) and the magnetic scalar potential($\Omega$) as field variable, and adopt image charge method for symetric boundary condition in BEM. We apply the hybrid method to electromagnet for levitation system and analyze the charateristics of eddy current airgap flux distribution, attractive and magnetic drag force according to velocity.

• 소음진동
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• 제9권1호
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• pp.131-140
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• 1999

A method to reconstruct the sound field around a Korean bell is developed. The sound radiation problem is formulated based on the boundary element method by using the algorithm of the acoustical holography. Sound pressures at the hologram surface are measured and used as input data for the analysis program that was developed in this study. An error minimization scheme is presented to overcome difficulties that arise in the backward reconstruction of the BEM-based acoustical holography In the model fictitious source surfaces were also introduced to reduce the complexity stemmed from the source shape. The sound field associated with the (4.0) vibrational mode of the Korean bell was visualized and verified experimentally.

• 한국전자파학회지:전자파기술
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• 제5권3호
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• pp.14-21
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• 1994

본 논문에서는 임의의 형태와 매질성분을 갖는 3차원 물체의 RCS(Radar Cross Section)를 구하기 위한 수 치켜 방법을 제시한다 RSC는 3차원 경계요소볍(3-DBEM)을 사용하여 다충산란체에 관한 표면적분방정식을 해석함으로서 구한다. 본 논문에서는 3차원적 경계요소법의 타당성과 유용성을 보이기 위하여 산란체의 형태를 비스듬한 입사전계로 부터 다충 정6변체 및 직6면체를 선택하였으며, 손실을 갖는 유전체 및 자성체의 경우에도충분히 적용될수 있도록 고찰하였다.

• 한국자기학회지
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• 제18권6호
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• pp.221-224
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• 2008

본 논문에서는 함정 선체의 갈바닉 부식 전류에 의해 발생되는 수중 전기장 신호를 경계요소 해석 도구인 FNREMUS 소프트웨어를 이용하여 예측하고, 예측된 신호로부터 함정 전기장 신호 특성을 특이치 분해(singular value decomposition) 방법을 이용하여 등가적으로 다이폴 모델링하는 방법에 대해 기술하고 있다. 제안된 다이폴 모델링 기법은 30 m 심도에서 예측된 경계요소 해석 결과와의 평균 차이 비교 방법을 통해 타당함이 확인되었다. 본 논문에서 제안된 모델링 기법을 이용하면 함정에서의 다양한 심도 변화에 따른 수중 정 전기장 신호 분포 특성 예측 및 분석이 가능하다.

• International Journal of Naval Architecture and Ocean Engineering
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• 제6권3호
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• pp.562-577
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• 2014

A reliable steady/transient hydro-elastic analysis is developed for flexible (composite) marine propeller blade design which deforms according to its environmental load (ship speed, revolution speed, wake distribution, etc.) Hydro-elastic analysis based on CFD and FEM has been widely used in the engineering field because of its accurate results however it takes large computation time to apply early propeller design stage. Therefore the analysis based on a boundary element method-Finite Element Method (BEM-FEM) Fluid-Structure Interaction (FSI) is introduced for computational efficiency and accuracy. The steady FSI analysis, and its application to reverse engineering, is designed for use regarding optimum geometry and ply stack design. A time domain two-way coupled transient FSI analysis is developed by considering the hydrodynamic damping ffects of added mass due to fluid around the propeller blade. The analysis makes possible to evaluate blade strength and also enable to do risk assessment by estimating the change in performance and the deformation depending on blade position in the ship's wake. To validate this hydro-elastic analysis methodology, published model test results of P5479 and P5475 are applied to verify the steady and the transient FSI analysis, respectively. As the results, the proposed steady and unsteady analysis methodology gives sufficient accuracy to apply flexible marine propeller design.

• Structural Engineering and Mechanics
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• 제20권2호
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• pp.225-239
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• 2005

Applications of the Trefftz boundary element method (BEM) to anti-plane electroelastic problems are presented in this paper. Both direct and indirect methods with domain decomposition are discussed in details. Each crack is treated as semi-infinite thin slit defined in a subregion, for which a particular solution of the anti-plane problem, satisfying exactly the crack-face condition, is derived. The stress intensity factors defined at each crack tip can be directly computed from the coefficients of the particular solution. The performance of the proposed formulation is assessed by two examples and comparison is made with results obtained by other approaches. The Trefftz boundary element approach is demonstrated to be suitable for the analysis of the anti-plane problem of piezoelectric materials.

• 한국생산제조학회지
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• 제6권4호
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• pp.65-71
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• 1997

The automation of mesh generation in BEM is very important in numerical analysis field for the time and efficiency. In order to this problem, program and algorithm to achive the purpose of making input data and automation of mesh generation based in Expert System are developed in this study. This program has the function of rotating and zooming. The stress intensity factor which is a criteria of fracture mechanics is calculated and compared with other results to prove efficiency and availability of the program in result.