• Title/Summary/Keyword: 경계요소법

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Design of Interference Type Noise Barrier Using The BEM (경계요소법을 이용한 간섭형 방음벽의 설계)

  • Lee, Seung-Young;Lee, Sang-Kwon;Cho, Sung-Hwan
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2002.11b
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    • pp.749-754
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    • 2002
  • This paper investigates the insertion loss of nosie barrier with a interference device. The efficiency of the conventional interference-type noise barrier depends on specific frequency. Thus this study is performed to improve the efficiency of the nosie barrier in the range of broadband frequency, by changing the shape of interference device and adding the channel with various depths. The boundary element method (BEM) is used to predict the insertion loss of noise barrier. Two-dimensional boundary element model is created to simulate the performance of long barrier with a line source.

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전자장 해석에의 경계요소법 응용

  • 고창섭;정현교
    • 전기의세계
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    • v.39 no.3
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    • pp.32-38
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    • 1990
  • 1960년대 후반 유한요소법인 전자장 수치해석에 응용되기 시작한 후 전기기기 특성해석, 성능예측 및 설계에 많은 도움을 주었다. 그동안 실제 모델에 응용된것은 거의가 2차원 문제에 국한되었다. 그러나, 최근 들어서는 각종 전기기기가 경량화, 소형화, 고효율화 됨에 따라 점차로 3차원 전자장 수치해석에 대한 요구가 급증하고 잇다. 앞서 언급한 바와 같이 유한요소법은 영역법의 일종으로 영역을 적절히 요소분할 하는데 어려움이 있다. 따라서 근래에 영역법의 문제점을 보완하기 위하여, 또한 영역법으 대용으로 경계법에 대한 연구가 점차로 증대되고 있다. 경계요소법은 주어진 지배방정식에 대한 Green 함수를 반드시 알아야만 하는 단점을 갖고 있으나 근래에 들어서는 광범위한 분야에 걸쳐 Grem함수가 이미 발전되어 있기 때문에 실제 응용에는 별 문제가 없으리라 생각된다.

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Boundary Element Evaluation of Stress Intensity Factor for Interface Crack in Elastic and Viscoelastic Composite Materials (경계요소법에 의한 탄성-점탄성 복합구조체의 계면균열 해석)

  • 이상순;김정규;황종근
    • Computational Structural Engineering
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    • v.9 no.1
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    • pp.85-91
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    • 1996
  • The focus of the present work is on the computation of the stress intensity factor for the crack at the elastic-viscoelastic bimaterial interface. First, the stress intensity factor for an interface crack in dissimilar elastic and viscoelastic materials is dervied by applying the correspondence principle to associated elastic expression. Then the time-domain boundary element analysis is performed to calculate the stress intensity factor. Numerical results show that the proposed method is very useful for the analysis of the interface crack in elastic and viscoelastic materials.

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Nondestructive Defect Detection in Two-dimensional Anisotropic Composite Elastic Bodies Using the Boundary Element Method (경계 요소법을 이용한 2차원 비등방성 복합재료 탄성체의 비파괴 결함 추정)

  • 이상열
    • Journal of the Computational Structural Engineering Institute of Korea
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    • v.17 no.1
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    • pp.39-47
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    • 2004
  • In this paper, the defects of two-dimensional anisotropic elastic bodies are identified by using the boundary element method. The use of numerical models that contain only boundary integral terns reduces the dimensionality of the problem by one. This advantage is particularly important in problems such as crack mechanics. Avoiding domain meshing is also particularly advantageous in the solution of inverse problems since it overcomes mesh perturbations and simplifies the procedure. In this paper, nondestructive approaches for the existing isotropic materials are extended to analyze the elastic bodies made of anisotropic materials such as composites. After verifying that the proposing boundary element model is in good agreement with numerical results reported by other investigators, the effect of noise in the measurements on the identifiability is studied with respect to different design parameters of layered composites. Sample studies are carried out for various layup configurations and loading conditions. The effects of the layup sequences in detecting flaw of composites is explored in this paper.

Design of Acoustic Source Array Using the Concept of Holography Based on the Inverse Boundary Element Method (역 경계요소법에 기초한 음향 홀로그래피 개념에 따른 음원 어레이 설계)

  • Cho, Wan-Ho;Ih, Jeong-Guon
    • The Journal of the Acoustical Society of Korea
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    • v.28 no.3
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    • pp.260-267
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    • 2009
  • It is very difficult to form a desired complex sound field at a designated region precisely as an application of acoustic arrays, which is one of important objects of array systems. To solve the problem, a filter design method was suggested, which employed the concept of an inverse method using the acoustical holography based on the boundary element method. In the acoustical holography used for the source identification, the measured field data are employed to reconstruct the vibro-acoustic parameters on the source surface. In the analogous problem of source array design, the desired field data at some specific points in the sound field was set as constraints and the volume velocity at the surface points of the source plane became the source signal to satisfy the desired sound field. In the filter design, the constraints for the desired sound field are set, first. The array source and given space are modelled by the boundary elements. Then, the desired source parameters are inversely calculated in a way similar to the holographic source identification method. As a test example, a target field comprised of a quiet region and a plane wave propagation region was simultaneously realized by using the array with 16 loudspeakers.

The Study on Scattered Far-Field Analysis of Ultrasonic SH-Wave Using Boundary Element Method (경계요소법을 이용한 SH형 초음파 원거리 산란장 해석에 관한 연구)

  • Lee, Joon-Hyun;Lee, Seo-Il
    • Journal of the Korean Society for Nondestructive Testing
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    • v.19 no.5
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    • pp.333-339
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    • 1999
  • It is well recognized that ultrasonic technique is one of the most common and reliable nondestructive evaluation techniques for quantitative estimation of defects in structures. For the quantitative and accurate estimation of internal defects. the characteristics of scattered ultrasonic wavefields must be understood. In this study. the scattered near-field and far-field due to a circular cavity embedded in infinite media subjected to incident SH-waves were calculated by the boundary element method. The frequency response of the scattered ultrasonic far-field was transformed into the time-domain signal by obtaining its inverse Fourier transform. It was found that the amplitude of time-domain signal decreases and its time delay increases as the distance between the detecting point of ultrasonic scattered field and the center of internal cavity increases.

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Guided Wave Tomographic Imaging Using Boundary Element Method (경계요소법을 이용한 유도초음파 토모그래피 영상화 기법)

  • Piao, Yunri;Cho, Youn-Ho;Jin, Lianji;Ahn, Bong-Young;Kim, Noh-Yu;Cho, Seung-Hyun
    • Journal of the Korean Society for Nondestructive Testing
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    • v.29 no.4
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    • pp.338-343
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    • 2009
  • Tomography is the imaging method of cross sectional area using multi beam signals and is mainly applied to the medical diagnosis to acquire the image of the inside human body. This method is pretty meaningful in nondestructive evaluation field since the imaging of the inspection region can enhance the comprehension of the inspector. Recently, much attention has been paid to the guided wave for the diagnosis of platelike structures. So, in this work, a study on the imaging of the damage location in a plate was carried out on the basis of computer aided analysis of guided waves and tomographic imaging. To this end, boundary element method was employed to analyze the effect of the damage in plate on the propagation of the guided waves and the analytic results were applied to the tomographic imaging method to identify the damage location. Consequently, it was shown that the number of sensors heavily affect the inspection performance of the damage location.

Time-Domain Simulation of Nonlinear Free-Surface Flows around a Two-Dimensional Hydrofoil (2차원 수중익주위 비선형 자유표면유동의 시간영역 시뮬레이션)

  • Yong-J. Kim
    • Journal of the Society of Naval Architects of Korea
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    • v.31 no.2
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    • pp.45-56
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    • 1994
  • A computationally efficient numerical method based on potential flow is developed for time-domain simulation of the nonlinear free-surface flows around a 2-dimensional hydrofoil. This numerical method, namely, spectral/boundary-element method, is a mixed one of the high-order spectral method and the boundary-element method in time-domain. The high-order spectral method is used to calculate the nonlinear evolution of free-surface, and the boundary-element method is used to calculate the effects of the hydrofoil and the shed vortex. As application examples, nonlinear free-surface flows around a 2-dimensional hydrofoil which starts from the rest and translates near the free-surface with or without harmonic oscillations are calculated. Nonlinear/unsteady results of free-surface waves and hydrodynamic farces are shown and discussed. Particularly, the results of steady-state which are obtained as a special case of the present unsteady solution are compared with others' calculated and experimental results, and good agreements are observed.

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