• Design & Manufacturing
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• v.8 no.2
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• pp.7-11
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• 2014

The Core-Shift is often generated on injection mold which have thin and long core. And Core-Shift brings out problems for thickness variation and product ejecting process. In this study, analysis of Core-Shift was performed according to change of materials of core(steel P-20, Be-Cu) and various polymers(PP, PC) by using MoldFolw MPI 6.1 which is commercial injection molding analysis program. As the results of analysis, the magnitude of Core-Shift was increased as being use polymer had lower fluidity and lower rigidity core. In the future, we will study the relationship between amount of Core-Shift and ejecting force.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2000.10a
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• pp.178-184
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• 2000

To obtain high quality component with thixoforming process, it is important that the homegeneous distribution of solid particles without liquid segregation. In closed-die semi-solid forging process, liquid segregation is strongly affected by injection velocity than any other process variables because the material has to travel relatively long distance to fill the cavity through a narrow gate before solidification begins. The optimal injection velocity and die temperature were investigated to fabricate near-net-shape compressor component called Al frame.

• Transactions of Materials Processing
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• v.7 no.4
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• pp.375-381
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• 1998

This paper presents development of finite element simulation program and analysis of hot extrusion through square dies with a mandrel. The design of extrusion dies is still an art rather than science. Die design for a new extrusion process is developed from through in-plant trials. In the present paper, a three-dimensional steady-state finite element simulation program is developed. Steady-state assumption is used for both the analyses of deformation and temperature. The developed program is effectively used to simulate hollow extrusion of several sections. Distributions of temperature effective strain rate, mean strain rate and mean stress are studied for an effective design of extrusion dies.

• Transactions of Materials Processing
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• v.21 no.2
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• pp.119-125
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• 2012

The present study addresses a direct patterning process on a plastic film using ultrasonic vibration energy. In this process, a tool horn containing micro-patterns is attached to an ultrasonic power supply, and is used with ultrasonic vibration to replicate micro-patterns on the surface of a plastic film. To improve the replication characteristics of the micro-patterns, the effect of the die shape of the ultrasonic patterning process was investigated with respect to the flow direction control. Finite element analyses were performed to predict the flow characteristics of the polymer with variations in die design parameters. Experiments were conducted using the optimally-designed die, from which it was possible to attain much improved pattern replication.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2003.06a
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• pp.405-408
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• 2003

Generally, the life of casting mold is limited by fatigue fracture or dimensional inaccuracy originated from wear in high temperature. Although recent research of metallic materials in high temperature fatigue have been much accomplished, many studies on brittle material as a die steel in high temperature fatigue does not have been reported. Especially, the study on the fatigue behavior over the transformation temperature is not studied sufficiently because of its difficult analysis and experiment. Therefore, reliable results of brittle material in high temperature fatigue behavior are needed. In this paper, stress-strain curves and stress-life curves in die STD61 steel are carefully examined between room temperature and 90$0^{\circ}C$, as the basic experimental data are used to predict from fatigue life of casting mold.

• Journal of the Microelectronics and Packaging Society
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• v.5 no.2
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• pp.37-48
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• 1998

The popcorn cracking phenomena in plastic IC packages during reflow soldering are investigated by considering the heat transfer and moisture diffusion through the epoxy molding compound(EMC) along with the mechanics of interface delamination. Heat transfer and moisture diffusion through EMC under die pad are analyzed by finite difference method (FDM)during the pre-conditioning and subsequent reflow soldiering pro-cess and the amounts of moisture mass and vapor pressure at delaminated die pad/ EMC interface are calculated as a function of the reflow soldering time. The energy release rate stress intensity factor and phase angle were obtained under various loading conditions which are thermal crack face vapor pressure and mixed loadings. It was shown that thermal loading was the main driving force for the crack propagation for small crack lengths but vapor pressure loading played more significant role as crack grew.

• Transactions of Materials Processing
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• v.14 no.2 s.74
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• pp.139-144
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• 2005

It was investigated that curved aluminum products with 'ㄷ' section or with 'h' section could be bended during extrusion by the extru-bending process. In order to make bending at the exit section of die, the flow of billet inside die cavity was controlled by the shape of billet. As results of the analysis of $DEFORM^{™}-3D$, it was known that the bending phenomenon at the die exit can be happened by the asymmetric section of billet. And it was known by the experiment with plasticine or aluminum material that an symmetric product with 'c' channel section and the product with flanged 'h' section could be bended because of asymmetric shape of billet.

• Transactions of Materials Processing
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• v.14 no.3 s.75
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• pp.207-214
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• 2005

Blanking process is widely used fur producing various structural parts. However, fine blanking technology is frequently used as a single step blanking operation with clean cut surface of a sheared surface because the fractured surface of parts causes serious problems in the final product and therefore it must be removed by the post-processing in case of the conventional blanking. In the present investigation, a fine blanking process was designed within the framework of progressive die to produce a carrier plate assembled within the auto transmission. Finite element analysis of the shearing behavior at the respective stage of the progressive fine blanking was conducted to validate the designed die parameters. Finally the designed progressive fine blanking process was experimentally evaluated by using the machined die.

• Transactions of Materials Processing
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• v.23 no.4
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• pp.206-210
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• 2014

The metal lead frame, a semiconductor component, has product tolerances in micro units as compared to products made with a larger size mold. Therefore, small deflections of the mold and of the press as well as the press molding process itself have a strong influence on accuracy of the product. Hence, it is necessary for the process design to consider the structural response of the mold and the press during deformation. In the current study, the mold deflection and pressure on the punch is examined using the finite element modeling (FEM) program ABAQUS. The results from the simulation were verified with the dynamic deformation measurement equipment using digital image correlation (DIC).

• Transactions of Materials Processing
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• v.13 no.2
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• pp.142-147
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• 2004

Three-dimensional rigid-plastic finite element analysis has been performed to optimize open die forging process to make round bar. In the round bar forging, it is difficult to optimize process parameters in the operational environments. Therefore in this study, finite element method is used to analyze the practice of open die forging, focusing on the effects of reduction, feeding pitch and rotation angle for optimal forging pass designs. The soundness of forging process has been estimated by the smoothness and roundness of the bar at various combination of feeding pitches and rotation angles. From the test result, process conditions to make round bar having precise dimensional accuracy have been proposed.