• Proceedings of the Korean Society of Precision Engineering Conference
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• 2008.11a
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• pp.539-540
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• 2008

• Transactions of the Korean Society of Automotive Engineers
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• v.3 no.1
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• pp.89-96
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• 1995

The application of the 4-pole parameter method with 1 - D theory is acceptable for intake system analysis. However, the limitaion appears during the analysis of complicated intake system since this method is developed based on the plane wave thoery. For the intake system analysis, the usage of BEM(Boundary Element Method) is introduced describing its disadvantage. To combine benefits of both method. a hybrid method is introduced. This hybrid method consists of the 4-pole parameter with I-D theory and BEM. The developed method is applied to an automobile intake system analysis to obtain the transmission loss.

• Proceedings of the KIEE Conference
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• 2001.07b
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• pp.748-750
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• 2001

This paper describes numerical analysis of eddy current testing for tube with axi-symmetric defect using boundary element method. In this ECT(Eddy Current Testing) numerical analysis. BEM and FEM are used to compare their characteristics and results of ECT, respectively BEM is easier than FEM to design geometrically complex domain because in case of BEM, domain is divided into segments or elements, but in case of FEM, domain is divided into small finite triangular or quadrilateral elements. For this reason asymmetry defect is used for this BE numerical analysis. As a result, the similar result can be obtained through both numerical analyses, and BEM can be applied to the numerical analysis of ECT.

• The Journal of the Acoustical Society of Korea
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• v.21 no.3E
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• pp.112-118
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• 2002

An unconstrained tuning fork with a 3-D model has been numerically analyzed by Finite Element Method (FEM) and Boundary Element Method (BEM). The first three natural frequencies were calculated by the FEM modal analysis. Then the trend of the change of the modal frequencies was examined with the variation of the tuning fork length and width. An formula for the natural frequencies-tuning fork length relationship were derived from the numerical analysis results. Finally the BEM was used for the sound pressure field calculation from the structural displacement data.

• Structural Engineering and Mechanics
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• v.13 no.4
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• pp.437-453
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• 2002

In this paper, dynamic stiffness and flexibility for circular membranes are analytically derived using an efficient mixed-part dual boundary element method (BEM). We employ three approaches, the complex-valued BEM, the real-part and imaginary-part BEM, to determine the dynamic stiffness and flexibility. In the analytical formulation, the continuous system for a circular membrane is transformed into a discrete system with a circulant matrix. Based on the properties of the circulant, the analytical solutions for the dynamic stiffness and flexibility are derived. In deriving the stiffness and flexibility, the spurious resonance is cancelled out. Numerical aspects are discussed and emphasized. The problem of numerical instability due to division by zero is avoided by choosing additional constraints from the information of real and imaginary parts in the dual formulation. For the overdetermined system, the least squares method is considered to determine the dynamic stiffness and flexibility. A general purpose program has been developed to test several examples including circular and square cases.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2002.05a
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• pp.772-777
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• 2002

A BEM is highly efficient method in the sense of economic computation. However, boundary integration is not easy for the complex and moving surface e.g. in a rotating blade. Thus, Kirchhoff surface is designed in an effort to overcome the difficulty resulting from complex boundary conditions. A Kirchhoff surface is a fictitious surface which envelopes acoustic sources of main concern. Acoustic sources may be distributed on each Kirchhoff surface element depending on its acoustic characteristics. In this study, an axial fan is assumed to have loading noise as a dominant source. Dipole sources can be computed based on the FW-H equation. Acoustic field is then computed by changing Kirchhoff surfaces on which near-field is implemented, to analyze the effect of Kirchhoff surface on it.

• The Transactions of the Korean Institute of Electrical Engineers B
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• v.49 no.7
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• pp.457-461
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• 2000

The finite element method (FEM) is suitable for the analysis of a complicated region that includes nonlinear materials, whereas the boundary element method (BEM) is naturally effective for analyzing a very large region with linear characteristics. Therefore, considering the advantages in both methods, a novel algorithm for the alternate application of the FEM and BEM to magnetic field problems with the open boundary is presented. This approach avoids the disadvantages of the typical numerical methods with the open boundary problem such as a great number of unknown values for the FEM and non-symmetric matrix for the Hybrid FE-BE method. The solution of the overall problems is obtained by iterative calculations accompanied with the new acceleration method.

• Proceedings of the KSME Conference
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• 2007.05a
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• pp.730-735
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• 2007

This study is a comparison of the results of the orthropic material analysis at cantilever beam model using boundary element(BEM) method and finite element method(FEM). The program with the orthotropic material analysis was developed and applied to the examples in order to evaluate the accuracy of the programs. The examples shows that the results of the BEM is a good agreement with the ABAQUS results.

• Coupled systems mechanics
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• v.4 no.3
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• pp.263-277
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• 2015

This paper presents a coupled FEM-BEM strategy for the numerical analysis of elastodynamic problems where infinite-domain models and complex heterogeneous media are involved, rendering a configuration in which neither the Finite Element Method (FEM) nor the Boundary Element Method (BEM) is most appropriate for the numerical analysis. In this case, the coupling of these methodologies is recommended, allowing exploring their respective advantages. Here, frequency domain analyses are focused and an iterative FEM-BEM coupling technique is considered. In this iterative coupling, each sub-domain of the model is solved separately, and the variables at the common interfaces are iteratively updated, until convergence is achieved. A relaxation parameter is introduced into the coupling algorithm and an expression for its optimal value is deduced. The iterative FEM-BEM coupling technique allows independent discretizations to be efficiently employed for both finite and boundary element methods, without any requirement of matching nodes at the common interfaces. In addition, it leads to smaller and better-conditioned systems of equations (different solvers, suitable for each sub-domain, may be employed), which do not need to be treated (inverted, triangularized etc.) at each iterative step, providing an accurate and efficient methodology.

• Transactions of the Korean Society of Mechanical Engineers
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• v.16 no.5
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• pp.883-890
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• 1992

Analysis of dynamic or impact problems is very important in engineering fields such as airplanes and automobiles. In the present study, two-dimensional elastodynamic BEM program with Laplace transformation is developed to analyze dynamic or impact problems. Accuracy and efficiency of the BEM program are tested by making the comparision of impact analysis of some models with other's published results. The BEM developed is applied to the impact crack problem and the dynamic stress intensity factors of some impact cracks is obtained by the displacement extrapolation method. It is confirmed to be possible to analyze impact problems accurately with only a little elements in simple models. And also it is found to be careful to use the singular element usually using in static crack problems because that the elastodynamic fundamental solution usually using in static crack problems because that the elastodynamic fundamental solution has more sensitive singularity than the static fundamental solution and to determine the boundary conditions in dynamic problems.