• Transactions of the Korean Society of Mechanical Engineers A
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• v.26 no.3
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• pp.461-470
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• 2002

The present paper investigates the effect of hot isostatic pressing (HIPing) on mechanical properties, e.g., tensile strength, ductility and impact absorption energy of sand and die casted aluminum alloys. After HIPing at various temperatures and pressure conditions, uniaxial tensile test and Izod impact test of the samples were carried out. The experimental results showed improvements in uniaxial tensile strength, elongation and Izod impact toughness of sand casted aluminum alloy, while deterioration of a tensile strength fur die casted aluminum alloy. The effect of HIPing for microstructure of the cast aluminum alloy was also investigated.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2001.07a
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• pp.776-779
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• 2001

The main objective of this paper is to design and mechanical strength analysis of UHV(Ultra High Voltage) suspension insulator. One of the important properties required for suspension insulators is mechanical strength under tensile load. The cement and porcelain part are express according to change of pin head type an aspect mechanical stress. These insulators are designed and produced by using the computer analysis of mechanical, electrical and electrical stresses together with the technical know-how accumulated from long years of study into every respect of insulators.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.20 no.10
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• pp.3113-3125
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• 1996

The objective of this study is to develop novel method named mechanical and chemical machining technique, which is capable of producing three dimensional patterns of few micrometers in dimension on a silicon wafer without the use of a mask. The strategy is to impart mechanical energy along the path of the pattern to be fabricated on a single crystal silicon by way on introdusing frictional interaction under controlled conditions. Then, the surface is preferentially etched to reveal the areas that have been mechanically energized. Upon completion of the etching process, the three dimensional pattern is produced on the silicon surface. Experiments have been conducted to identify the optimal tool material, geometery, as well as fabrication condition. The new technique introduced in this paper is significantly simpler than the conventional method which require sophisticated equipment and much time.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.26 no.7
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• pp.1302-1308
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• 2002

Thermo-mechanical and flexural behavior of a wire-bond plastic ball grid array (WB-PBGA) package are characterized by high sensitive moire interferometry. Moire fringe patterns are recorded and analyzed for several bending loads and temperatures. At the temperature higher than $100^{\circ}C$, the inelastic deformation in solder balls become more dominant, so that the bending of the molding compound decreases while temperature increases. The deformation caused by thermally induced bending is compared with that caused by mechanical bending. The strain results show that the solder ball located at the edge of the chip has largest shear strain by the thermal load while the maximum average shear strain by the bending moment occurs in the end solder.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.34 no.6
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• pp.709-715
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• 2010

The coupled model with hydrogen transport and elasto-plasticity behavior was introduced. In this paper, the effective factor of the hydrogen diffusion equation has been described. To assess the effective factor, finite element (FE) analyses including hydrogen transport and mechanical loading for boundary layer specimens with low-strength steel properties are carried out. The results of the FE analyses are compared with those from previous studies conducted by Taha and Sofronis (2001).

• Transactions of the Korean Society of Mechanical Engineers A
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• v.24 no.12
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• pp.3033-3039
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• 2000

Mechanical properties of the materials used for transportations and industrial machinery under high stain rate loading conditions have been required to provide appropriate safety assessment to these mechanical structures. The Split Hopkinson Pressure Bar(SHPB) technique with a special experimental apparatus can be used to obtain the material properties under high strain rate loading condition. There have been many studies on the material behavior under high strain rate compressive loading compared to those under tensile loading. In this paper, mechanical properties of the aluminum alloy, Al6061-T6, under high strain rate tensile loading were determined using SHPB technique.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.26 no.3
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• pp.417-422
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• 2002

The experiments have been carried out to evaluate the cooling performance of a fan-aluminum foam heat sink assembly in comparison with a conventional CPU cooler. In terms of the dimensionless surface temperature of the heater, the cooling performance of the aluminum foam heat sink is similar to that of the conventional one with much reduced weight. The optimum fin height is found to be strongly dependent on the fin height of the heat sink and flow characteristics of the cooling fan.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.20 no.1
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• pp.172-179
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• 1996

For mechanical systems operating at high tempertature, thermal fatigue phenomenon has been recognized as a major cause of mechanical component failures. To evaluate cumulative fatigue damage as a conesquence of thermal fatugue on real time, the stress tranfer function(Green's function) approach is popularly used. The objective of this paper is to investigate the effect of thermophsical properties on the stress tranfer function. For this purpose a modified Green's function approach considering temperature-dependent thermophysical properties is proposed. Two case studies were performed and the proposed approach agrees well with full finite element analysis.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2005.11a
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• pp.358-359
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• 2005

Chemical mechanical polishing(CMP) process depends on a variety of variables. Especially, surface roughness of pad plays a key role in material removal in CMP in terms of transportation ability of pores and real contact area. The surface roughness is deteriorated with polishing time by applied pressure and relative velocity. In this reason, diamond conditioner has been used to maintain the roughness on the pad. The authors try to investigate the correlation between pad roughness and frictional behavior by comparing ex-situ conditioning with in-situ conditioning.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.26 no.1
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• pp.31-38
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• 2002

A new steering-type web position control system for cold mills using QFT is presented. The control system features an inner-outer cascaded system in which the inner loop provides the position tracking control of hydraulic system and the outer loop provides the position regulation control of the web. By the sensitivity analysis and computer simulation, it is verified that the proposed control system has better robust stability and performance than the conventional PH) control system.