• KIEE International Transaction on Electrical Machinery and Energy Conversion Systems
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• v.3B no.1
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• pp.16-22
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• 2003

This paper presents an application of an impedance boundary condition to 3D vector finite element analysis of a multi-port cylidrical microwave cavity using Snell's law. Computing memory benefits and computing time reduction are obtained from this method compared with the conventional finite element method(FEM). To verify the method, a high permittivity scatterer in free space is analyzed and compared with the results of conventional (FEM). In addition, this method has been analyzed several types of cavities, including water load, to demonstrate the validity and accuracy of the program.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2002.11a
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• pp.401.2-401
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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 change of the modal frequencies was examined with the variation of the tuning fork length and width. (omitted)

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1997.10a
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• pp.668-671
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• 1997

In order to investigate the vibration characteristics of fluid-structure interaction problem, we modeled two identical rectangular plates coupled with bounded fluid. The fixed boundary condition along the plate edges and an ideal fluid were assumed. A commercial computer code, ANSYS was used to perform finite element analysis and FEM solutions were compared with the experimental results to modify the finite element model. As a result, comparison of FEM and experiment showed good agreement, and the transverse vibration modes, in-phase and out of-phase. were observed alternately in the tluid-coupled system. The effects of distance between two rectangular plates and width to length ratio on the fluid-coupled natural frequency were investigated. And it was found that the ormalized natural frequency of the fluid-coupled system monotonically increased with an increase in the number of modes.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.58 no.9
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• pp.1815-1820
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• 2009

The FEM(Finite Element Method) is widely adopted numerical technique for finding approximate solutions of various engineering problems in which partial differential equations (PDEs) are involved. Although the original purpose of the FEM is focused on numerical analysis itself due to its heavy computation time, this method has been adopted into control engineering field during the last decade to improve product or system performance. In this paper, this trend is briefly introduced.

• Smart Structures and Systems
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• v.15 no.1
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• pp.99-117
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• 2015

The Stonecutters Bridge (SCB) in Hong Kong is the third-longest cable-stayed bridge in the world with a main span stretching 1,018 m between two 298 m high single-leg tapering composite towers. A Wind and Structural Health Monitoring System (WASHMS) is being implemented on SCB by the Highways Department of The Hong Kong SAR Government, and the SCB-WASHMS is composed of more than 1,300 sensors in 15 types. In order to establish a linkage between structural health monitoring and maintenance management, a Structural Health Rating System (SHRS) with relevant rating tools and indices is devised. On the basis of a 3D space frame finite element model (FEM) of SCB and model updating, this paper presents the development of an SHR-oriented 3D multi-scale FEM for the purpose of load-resistance analysis and damage evaluation in structural element level, including modeling, refinement and validation of the multi-scale FEM. The refined 3D structural segments at deck and towers are established in critical segment positions corresponding to maximum cable forces. The components in the critical segment region are modeled as a full 3D FEM and fitted into the 3D space frame FEM. The boundary conditions between beam and shell elements are performed conforming to equivalent stiffness, effective mass and compatibility of deformation. The 3D multi-scale FEM is verified by the in-situ measured dynamic characteristics and static response. A good agreement between the FEM and measurement results indicates that the 3D multi-scale FEM is precise and efficient for WASHMS and SHRS of SCB. In addition, stress distribution and concentration of the critical segments in the 3D multi-scale FEM under temperature loads, static wind loads and equivalent seismic loads are investigated. Stress concentration elements under equivalent seismic loads exist in the anchor zone in steel/concrete beam and the anchor plate edge in steel anchor box of the towers.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2001.11a
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• pp.207-212
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• 2001

This paper considers a pipeline conveying one-dimensional unsteady flow inside. The dynamics of the fluid-pipe system is represented by two coupled equations of motion for the transverse and axial displacements, which are linearized from a set of partial differential equations which consists of the axial and transverse equations of motion of the pipeline and the equations of momentum and continuity of the internal flow. Because of the complex nature of fluid-pipe interactive mechanism, a very accurate solution method is required to get sufficiently accurate dynamic characteristics of the pipeline. In the literatures, the finite element models have been popularly used for the problems. However, it has been well recognized that finite element method (FEM) may provide poor solutions especially at high frequency. Thus, in this paper, a spectral element model is developed for the pipeline and its accuracy is evaluated by comparing with the solutions by FEM.

• Journal of Ocean Engineering and Technology
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• v.13 no.2 s.32
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• pp.41-50
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• 1999

As for the properties on both the aluminum and the CFRP which are used to make A17075/CFRP multi-layered hybrid composites, CRALL(carbon reinforced aluminum laminate). In the CRALL specimen for rule of mixture, we were analyzed notched strength by finite element method. The results obtained from FEM analysis are as follows; In the unnotch CRALL specimen, the stresses CFRP, epoxy, Al 7075 obtained by finite element method strength solution for A/C0001, when strain is 0.28%, are 1400MPa, 38MPa, 411MPa. respectively and for A/C9991, when strain 0.48%, are 392MPa, 26MPa and 321Mpa, respectively. the solpe of the stress-strain curve by FEM increases in keeping with the hole size and the yield strain decrease to 36% and 55% for A/C9993 and A/C9991 respectively.

• Journal of Power System Engineering
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• v.11 no.4
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• pp.78-85
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• 2007

In order to analyze accurately the vibration of a structure by using the finite element method (FEM), we have to model a analytical structure as a numerical model with many degrees-of-freedom. However, in this case, the FEM needs much computation time and storage. The authors developed the finite element-transfer stiffness coefficient method (FE-TSCM) for overcoming the drawback of the FEM. In this paper, the authors apply the FE-TSCM to the in-plane vibration analysis of general plates with various shapes. Two numerical examples, a rectangular plate and a triangular plate, are used to compare the results of the FE-TSCM and the FEM. Through the numerical calculation, we confirm that the FE-TSCM can be applied to the in-plane free or forced vibration analysis of the general plates with various shapes and is effective to in-plane vibration analysis of general plates.

• East Asian mathematical journal
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• v.33 no.5
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• pp.495-509
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• 2017

With the accuracy of the nonlinearity guaranteed, plenty of time and large memory space are needed when we solve the finite element numerical solution of nonlinear partial differential equations. In this paper, we use the Group Element Method (GEM) to deal with the non-linearity of the BBM-Burgers Equation with Conservation form and perform a numerical analysis for two particular initial-boundary value (the Dirichlet boundary conditions and Neumann-Dirichlet boundary conditions) problems with the Finite Element Method (FEM). Some numerical experiments are performed to analyze the error between the exact solution and the FEM solution in MATLAB.

• 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.