• 한국자동차공학회논문집
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• 제15권4호
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• pp.171-177
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• 2007

In this paper, an evaluation method of fracture toughness on interface cracks was investigated in friction welded dissimilar materials with interfacial edge cracks. To establish a reasonable strength evaluation method and fracture criterion, it is necessary to analyze stress intensity factor under the load and residual stress condition on friction welded interface between dissimilar materials. The friction welded specimens with an edged crack were prepared for analysis of stress intensity by using the boundary element method (BEM) and the fracture toughness. A quantitative fracture criterion for friction welded STS 304/SM 45C with interface crack is suggested by using stress intensity factor, F and the results of fracture toughness experiment.

• 한국지진공학회:학술대회논문집
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• 한국지진공학회 1997년도 춘계 학술발표회 논문집 Proceedings of EESK Conference-Fall 1997
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• pp.115-127
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• 1997

A study to evaluate the seismic response of $\frac{1}{2}$-scaled liquid storage tank constructed in Hualien, is performed. And this study is to identify the liquid-structure-soil interaction by observed earthquake data ans analyzed results. After the calculation of soil impedance for the test site by SASSI code, 3-dimensional seismic response analysis is performed by BEM-FEM-Impedance Method with the consideration of liquid-structure-soil interaction when the tank is excited by real earthquake. The observed acceleration and hydrodynamic pressure are compared with the numerical results. This comparisons show good agreement in predominant frequency and maximum hydrodynamic pressure. And the free surface sloshing motion due to earthquake loadings is computed in time domain.

• Structural Engineering and Mechanics
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• 제15권5호
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• pp.535-550
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• 2003

In this paper, a boundary-type meshfree method, the boundary radial point interpolation method (BRPIM), is presented for solving boundary value problems of two-dimensional solid mechanics. In the BRPIM, the boundary of a problem domain is represented by a set of properly scattered nodes. A technique is proposed to construct shape functions using radial functions as basis functions. The shape functions so formulated are proven to possess both delta function property and partitions of unity property. Boundary conditions can be easily implemented as in the conventional Boundary Element Method (BEM). The Boundary Integral Equation (BIE) for 2-D elastostatics is discretized using the radial basis point interpolation. Some important parameters on the performance of the BRPIM are investigated thoroughly. Validity and efficiency of the present BRPIM are demonstrated through a number of numerical examples.

• 한국전산구조공학회논문집
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• 제13권1호
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• pp.97-103
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• 2000

이 논문에서는, 반도체 칩과 리드프레임을 결합하는 과정에서 점탄성 접착제층에 발생하는 잔류응력 문제를 다루고 있다. 접착제층은 “열유동단순”거동을 한다고 가정하였다. 접착제층에서의 응력들은 경계요소법을 사용하여 조사하였다. 매우 큰 응력 구배가 계면 모서리에서 발생하는데, 그러한 응력들은 국부 항복을 일으키거나, 칩과 리드프레임의 박리를 야기시킬 수 있음을 보여주고 있다.

• Journal of Mechanical Science and Technology
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• 제19권8호
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• pp.1611-1620
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• 2005

This paper shows the use of wavelet transformation combined with inverse acoustics to reconstruct the surface velocity of a noise source. This approach uses the boundary element analysis based on the measured sound pressure at a set of field points, the Helmholtz integral equations and wavelet transformation for reconstructing the normal surface velocity field. The reconstructed field can be diverged due to the small measurement errors in the case of nearfield acoustic holography (NAH) using an inverse boundary element method. In order to avoid this instability in the inverse problem, the reconstruction process should include some form of regularization for enhancing the resolution of source images. The usual method of regularization has been the truncation of wave vectors associated with small singular values, although the order of an optimal truncation is difficult to determine. In this paper, a wavelet transformation is applied to reduce the computation time for inverse acoustics and to enhance the reconstructed vibration field. The computational speed-up is achieved, with solution time being reduced to $14.5\%$.

• 대한조선학회논문집
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• 제48권2호
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• pp.107-112
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• 2011

The aim of this study is to analyze the hydrodynamic properties of a 2D floating body with moon pool using a 2D fully nonlinear Numerical Wave Tank(NWT). This NWT was developed based on the Boundary Element Method(BEM) with potential theory and fully nonlinear free surface boundary conditions. Free surface elevations in the moon pool were calculated in the time domain for various frequencies of forced body motions. The added-mass and damping coefficients of the heaving body were also obtained. The present numerical results were compared with the analytic and experimental results and their accuracy was verified.

• 한국시뮬레이션학회:학술대회논문집
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• 한국시뮬레이션학회 2003년도 춘계학술대회논문집
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• pp.15-18
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• 2003

전자파 산란해석 방법으로서 유한요소법, 경계요소법 및 모멘트법 등은 임의 구조를 한 산란체의 산란현상을 다룰 수 있다. 그러나 이러한 해석방법들은 정상 파동문제를 다루는데 편중되어 있어 시간영역에서의 비정상 파동문제를 해석하기 위해서는 여러 가지 제약이 따른다. 본 논문에서는 본질적으로 시간영역 해석방법인 TLM(Transmission Line Matrix)법을 이용하여 프레넬 렌즈의 산란특성을 해석하고 키르호프의 근사식과 PO(Physical Optics)법과 비교 검토하여 그 유효성을 검증한다.

• 대한조선학회논문집
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• 제41권2호
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• pp.21-32
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• 2004

The non-cavitating noise of underwater propeller is considered numerically in this study. The main purpose is to analyze non-cavitating noise from underwater propellers in various operating conditions with different configurations. Noise is predicted by using time-domain acoustic analogy, boundary element method, and computational hydro-acoustics. The flow field is analyzed with potential-based panel method, and then time-dependant pressure data are used as the input for Focus Williams-Hawkings formulation to predict far field acoustics. Furthermore, boundary element method and computational hydro-acoustics are also considered to investigate duct propeller and ducted multi-stage propeller to consider the reflection and diffraction of sound waves. With this methodology, noise intensity and directivity of each noise sources could be well analyzed.

• 마이크로전자및패키징학회지
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• 제8권3호
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• pp.25-30
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• 2001

반도체 칩과 얇은 접착제충의 계면에 존재하는 모서리 균열에 횡방향 인장변형률이 작용하는 경우에 대해 응력확대계수를 조사하고 있다. 이러한 균열들은 자유 경계면 부근에 존재하는 응력 특이성으로 인해 발생할 수 있다. 계면 응력상태를 해석하기 위해서 경계요소법이 사용되고 있다. 복합 응력확대계수의 크기는 균열의 크기에 의존하지만, 균열이 커지면 일정한 값에 수렴한다. 횡방향 인장변형률이 임계값에 도달하면, 계면 균열은 빠르게 전파되리라고 예상된다.

• 대한가정학회지
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• 제24권4호
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• pp.199-207
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• 1986

The purpose of this study is two fold: 1) To find out if perceived parental child-rearing attitudes have any relationship with sex of children and education of the parents. 2) To investigate how and what extent perceived parental child-rearing attitudes affect the sex-role traits of children. In order to pursue the above purposes, the Bem Sex Role Inventory (BSRI) and perceived parental child-rearing attitudes questionnaire were administerd to 127 6th elementary school children in Gwang Ju. For data analysis, such techniques as multiple regression and pearson correlation were applied. The results of this study are summarized as follows: 1) Both boys and girls perceived more positive attitudes by mothers than by fathers 2) Some effects of sex differences and education of parents were found in the perceived parental child-rearing attitudes and sex-role traits of children. 3) Perceived parental attitudes had significant effects on children's sex-role traits.