• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2000.04a
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• pp.44-47
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• 2000

In industrial practice caliber design in shape rolling depends on the designer's experience which in general is obtained through costly trial-and error process. Demonstrated in this paper is an application of the finite element method to the determination of optimal caliber shapes in shape rolling of LM-Guide.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2001.10a
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• pp.183-190
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• 2001

Topology optimization. has been evolved into a very efficient conceptual design tool and has been utilized into design engineering processes in many industrial parts. In recent years, topology optimization has become the focus of structural optimization design and has been researched and widely applied both in academy and industry. Traditional topology optimization has been using homogenization method and optimality criteria method. Homogenization method provides relationship equation between structure which includes many holes and stiffness matrix in FEM. Optimality criteria method is used to update design variables while maintaining that volume fraction is uniform. Traditional topology optimization has advantage of good convergence but has disadvantage of too much convergency time and additive checkerboard prevention algorithm is needed. In one way to solve this problem, element remove method is presented. Then, it is applied to many examples. From the results, it is verified that the time of convergence is very improved and optimal designed results is obtained very similar to the results of traditional topology using 8 nodes per element.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.20 no.7
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• pp.2067-2077
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• 1996

In adaptive finite element analysis, r- and h-methods are generally used on the basis of a discretization error estimator. In this paper, an rh-method is proposed as a new adaptive method which can improve the adaptivity performance by using both of them. This suggested rh-method moves nodal coordinates of initially given model to adjust element discretization errors and thereafter performes the h-method tdo obtain the specified accuracy of finite element solutions. Numerical experiments for various plane problems were performed using 4-noded isoparametric quadrilateral elements. As a result, the rh-method has been shown to be an accurate and efficient adaptive analysis method to obtain as improved solution.

• Steel and Composite Structures
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• v.5 no.2_3
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• pp.203-233
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• 2005

This paper presents the findings of a design development project for perforated beams fully integrated with building services. A unified design approach for both steel and composite beams with large rectangular web openings is proposed which is based on plastic design methods and formulated in accordance with analytical structural design principles. Moreover, finite element models are established after careful calibration against test data, and comparison on the predicted ultimate loads of two composite beams with rectangular web openings from the finite element models and the proposed design method is also presented. It is demonstrated that the proposed design method is able to predict the ultimate loads of composite beams with rectangular web openings against 'Vierendeel' mechanism satisfactorily.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2002.07a
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• pp.115-118
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• 2002

This paper presents the design method and performance characteristics of a chip-type quadrature hybrid using LTCC-MLC technology. The design method for a chip-type quadrature hybrid is based on lumped element equivalent circuit of quarter-wave transformer. The chip-type quadrature hybrid was miniaturized to a greater extent using multilayer structure and lumped element. The proposed design method can also reduce the undesirable parasitic effects of the chip-type quadrature hybrid. The proposed chip-type quadrature hybrid was designed and fabricated using the proposed design method and the equivalent circuit model of a quarter-wave transformer. Fabrication and measurement of designed chip-type quadrature hybrid show much smaller size than a conventional distributed quadrature hybrid and a good agreement with simulated results.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2005.05b
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• pp.119-122
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• 2005

In this study, the design simulation for optimal wire batch around service line was made to improve the dielectric strength at the primary winding using Finite Element Method. The automatic convergence algorithm for finding of limit object value using loop circulation method was developed to make the optimal design simulator. The modulation method was suggested to make division time faster which was very important for full simulation efficiency. As a result, the simulation time was reduced and the optimal wire batch design was obtained.

• Transactions of Materials Processing
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• v.7 no.6
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• pp.562-569
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• 1998

The limit drawing ratio (LDR) is a major process parameter in the process design of deep drawing. If the actual drawing ratio is greater than the LDR for a particular stage then an intermediate stage has to b added the process sequence to avoid failure during the drawing operation and the optimal process design considering for the first-drawing and redrawing by using finite element method combined with ductile fracture criterion. From the results of finrte element analysis the optimal value of drawing ratio is obtained which contributes to the more uniform distribution of thickess and the smaller values of the ductile fracture infinal cup.

• Proceedings of the Korean Society For Composite Materials Conference
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• 2000.11a
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• pp.191-194
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• 2000

In this study, experimental verification of performance of flat speaker has been conducted. The piezofilm (PVDF) actuator has been designed to prevent the distortion of sound and make the frequency response of radiated sound flat. The electrode pattern of piezofilm actuator is optimized to satisfy the design objective. The formulation of design method is based on the coupled finite element and boundary element method and electrode pattern is optimized by genetic algorithm. The flat speaker with optimized piezofilm actuator has been manufactured. The sound pressure level at the distance of 50cm is measured using microphone and compared with the result of numerical simulation.

• Proceedings of the Korean Society of Agricultural Engineers Conference
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• 1998.10a
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• pp.119-123
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• 1998

New design automation method of R/C beam based on the finite element method and the nonlinear truss model approach has been presented. The proposed method can substitute inaccurate existing method, which has limitation in its application, provide accurate and efficient design results for any type of R/C beam.

• Journal of the Korean Society for Precision Engineering
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• v.20 no.8
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• pp.175-184
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• 2003

A method of the shape design sensitivity analysis based on the boundary integral equation formulation is presented for two-dimensional inhomogeneous thermal conducting solids with multiple domains. Shape variation of the external and interface boundary is considered. A sensitivity formula of a general performance functional is derived by taking the material derivative to the boundary integral identity and by introducing an adjoint system. In numerical analysis, state variables of the primal and adjoint systems are solved by the boundary element method using quadratic elements. Two numerical examples of a compound cylinder and a thermal diffuser are taken to show implementation of the shape design sensitivity analysis. Accuracy of the present method is verified by comparing analyzed sensitivities with those by the finite difference. As application to the shape optimization, an optimal shape of the thermal diffuser is found by incorporating the sensitivity analysis algorithm in an optimization program.