• Transactions of Materials Processing
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• v.10 no.3
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• pp.185-192
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• 2001

In order to obtain the optimal products in deep drawing process, elliptical deep drawing tests were carried out with several shape radii of the punch and die. As parameters on testing, shape radii of the punch and die were selected. In addition, the conventional shape radii have been determined by trial-and-error using industrial experience and post processing test, and only approximate shape radii of the punch and die have been presented. The optimal shape radii of the punch and die in elliptical deep drawing process with biaxisymmetric blank shape are proposed. In this study, we suggest the appropriate conditions to be applicable to the actual manufacturing processes through the experiment and finite element method.

• Proceedings of the International Microelectronics And Packaging Society Conference
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• 2002.05a
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• pp.117-120
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• 2002

In this paper, several methods to predict the solder joint shape are studied. Although there are various methods to predict the solder joint shape, such as truncated sphere method, force-bal tranced analytical solution, and energy-based methods like surface evolver developed by Ken Brakke, we calculate solder joint shape of $\mu$BGA by two solder joint shape prediction methods(truncated sphere method and surface evolver) and then compare results of each method. The results in dicate that two methods can accurately predict the solder joint shape in an accurate range. After that, we calculate reliability solder joint shape under thermal cycle test by FEA program ANSYS. As a result, it could be found that optimal solder joint shape calculated by solder joint prediction method has best reliability in thermal cycle test.

• Journal of Urban Science
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• v.7 no.1
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• pp.55-61
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• 2018

Long bridges, such as suspension bridges and diagonal bridges, are complex phenomena that show different behaviors depending on the shape and rigidity of the cross sections, such as wind vibrations and liquid vibrations from earthquakes in liquid storage containers. This is called the lower skirt on the lower side of the bridge, and the installation of lower skirt is effective for release and vortex vibrations caused by rapid winds, and that increases the stability of the wind resistance of the bridge. Optimal shape and installation of the lower skirt is also essential to make maximum wind speed effect of the lower skirt. Therefore, this study proposes a numerical analysis method to control the vibration of a bridge by calculating the optimal installation angle of an optimal lower skirt according to the optimal control theory and this study evaluates the impact on the optimal control system by minimizing the dominance equation with an evaluation function,which is an indicator for evaluating the optimal control theory state.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.30 no.11 s.254
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• pp.1479-1485
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• 2006

To minimize the leakage of microwave which can occur when one pulls the door of a microwave oven during its operation, shape optimization of the door frame is presented. A numerical optimization is implemented to minimize the dynamic twisting deformation of the door frame. Shape design variables are defined, which represent the dimension of the bead in the flange. Two optimal design problems are established to minimize the maximum twisting deformation from harmonic response analysis. The problems are solved, their results being compared and evaluated.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 1999.04a
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• pp.287-294
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• 1999

The tensegrity structure by prestressed cable, which may have large freedom in scale and form and therefore are received much attention from the view points of their light weight and aesthetics, is a very flexible and geometrically unstable structure because the cable material has little initial rigidity. For the stable self-equilibrated state of the usually very deformable structure, the method to find the optimal initial stress by the shape analysis is proposed in this paper. The proposed procedure is to derive the nonlinear finite element formula of cable and truss members considering geometric nonlinearity and used to modified load incremental method adding to Newton-Raphson method with the proposed condition for optimal initial stress. The result of the shape analysis for the tensegrity structure with the radius of 30m is shown the almost approximated shape to architectural shape and the changed procedure of initial stress

• Transactions of Materials Processing
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• v.13 no.1
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• pp.90-101
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• 2004

An inverse mosaic method has been proposed to generate an initial blank shape from the final product shape. Differently from the geometric mapping method, the method can handle triangular patches. However, the generated blank shape is strongly dependent on the order of determination of nodes. In order to compensate the dependency error smoothing technique has been also developed. Although the accuracy has been improved greatly compared with the geometrical mapping method, the method has limitation, due to the no incorporation of plasticity theory. Even though the accuracy of the radius vector method is already proved. the method requires initial guess to start the method. In order to compromise the limitation of the present method and the radius vector method, the method has been connected to the radius vector method. The efficiency of the present optimal blank design method has been verified with some chosen examples.

• Transactions of Materials Processing
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• v.17 no.3
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• pp.210-217
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• 2008

The effects of blank shape on the safety of stamped parts are studied through the comparison of an optimal blank and the corresponding reference blank shape to show further advantage of the optimal blank. In order to carry out this study, stamping process has been analyzed and the forming history, e.g. accumulated effective strain and thickness has been incorporated in the crash analysis. The reference blank has been determined following to the actual industry guideline, and excessive material to the desired shape has been trimmed off before crash analysis for the objective comparison. Through the study, appreciable increase of impact safety has not been observed and the effective of blank shape is verified not to be significant.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.31 no.2 s.257
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• pp.269-276
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• 2007

Optimal thickness and shape of the pedal arm of an automotive clutch is determined, using the numerical optimization technique, by solving the size and shape optimization problems to minimize its weight. For the optimization problems, two cases of stress and displacement constraints are considered: one from the vertical, and the other from the transverse stiffness test condition. The result of the transverse case is shown to be more conservative than that from the vertical case, being determined as the final optimum.

• Journal of applied mathematics & informatics
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• v.17 no.1_2_3
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• pp.315-328
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• 2005

In this paper we present a new method for designing a nozzle. In fact the problem is to find the optimal domain for the solution of a linear or nonlinear boundary value PDE, where the boundary condition is defined over an unspecified domain. By an embedding process, the problem is first transformed to a new shape-measure problem, and then this new problem is replaced by another in which we seek to minimize a linear form over a subset of linear equalities. This minimization is global, and the theory allows us to develop a computational method to find the solution by a finite-dimensional linear programming problem.

• Transactions of Materials Processing
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• v.5 no.4
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• pp.269-280
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• 1996

A new approach to die shape optimal design in extrusion is presented. The approach consists of a FEM analysis model to predict the value of the objective function a design model to relate the die profile with the design variables and a genetic algorithm based optimaization procedure. The approach was described in detail with emphasis on our modified micro genetic algorithm. Comparison with theoretical solutions was made to examine the validity of the predicted optimal die shapes. The approach was then applied to revealing the optimal die shapes with regard to various objective functions including those for which the design sensitivities can not be deter-mined analytically.