• Journal of the Korean Society of Manufacturing Process Engineers
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• v.7 no.1
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• pp.62-66
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• 2008

Machine parts subjected to fluctuating or cyclic loads induce repeated stresses that often result in failure by fatigue. In such cases, the fatigue failures unfortunately sometimes occur. These may arise from a lack of knowledge with regard to the design, fabrication and operation of the machines or structures. The failure analysis provides valuable information regarding the prevention of similar failures. Furthermore, this information will be useful to improve or to develop new products. Failure stress analysis is classified into X-ray fractography. X-ray fractography has the limited applications because of material crystal size, difficult measurement method, electrolytic polishing precision, and long test time. Therefore, this study proposed the new method to improve the measurement precision of plastic zone depth and test time using TRIZ.

• Proceedings of the Korean Powder Metallurgy Institute Conference
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• 2006.09a
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• pp.43-44
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• 2006

The production method of micro sacrificial plastic mold insert metal injection molding, namely ${\mu}-SPiMIM$ process has been proposed to solve specific problems involving the miniaturization of MIM. Two types of sacrificial plastic molds (SP-mold) with fine structures were used: 1) PMMA resist, 2) PMMA mold injected into Ni-electroform, which is a typical LIGA (${\underline{L}}ithographie-{\underline{G}}alvanoformung-{\underline{A}}bformung$) process. Stainless steel 316L feedstock was injection-molded into the SP-molds with multi-pillar structures. This study focused on the effects of metal particle size and processing conditions on the shrinkage, transcription and surface roughness of sintered parts.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2005.09a
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• pp.141-146
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• 2005

In the present study, the characteristic of warpage and flow balance for family mould, which is able to mold parts with different shapes in a mold, is considered. To obtain an optimal gate and runner system, plastic injection molding analysis with commercial code is performed. Design and manufacturing of family mould is then carried out on the basis of this computer aided engineering result. Flow balance and warpage comparisons between experiment and numerical analysis give good agreement with each other. However, it was shown that results of warpage measured by CMM was about $20\~55\%$ lower than those of numerical analysis.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2010.05a
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• pp.353-354
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• 2010

• Proceedings of the Korean Institute of Industrial Safety Conference
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• 1998.11a
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• pp.261-266
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• 1998

This paper presents a numerical simulation of the failure behaviour for the pipeline which has external corroded parts along the axis. The numerical study for the pipeline failure analysis is based on an FEM with an elastic-plastic and large-deformation. The predicted failure assessments for the simulated corrosion defects are compared with ANSI/ASME B31G code and a modified B31G method.

• Archives of Plastic Surgery
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• v.33 no.5
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• pp.587-591
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• 2006

Purpose: Since Rheinwald and Green laid the foundation of epidermal cell culture technology in 1975, many clinicians and scientists have attempted to prove the effectiveness of cultured epidermal autologous(CEA) or homogenetic(CEH) grafts in the wound healing process. In contrast to CEA which cultured from a patient's skin on demand, Cultured Epidermal Homograft(CEH) can be readily available to use on cleaned wounds. In this study, we conducted a controlled clinical trial in order to confirm the effectiveness of CEH in treating partial-thickness 2nd degree burn wounds. Methods: From July 2003 to January 2004 at Hangang Sacred Heart Hospital, we performed a clinical trial in which 35 patients who suffered from 2nd degree burns were enrolled. Wounds were randomly divided into two parts, control and test sites. Test sites were treated with allogeneic keratinocyte sheets ($Kaloderm^{(R)}$, Tegoscience Inc.), a CEH commercialized in Korea. Results: All wounds healed completely without any major complication. The complete healing took $8.3{\pm}2.8$($mean{\pm}S.D.$) days in the test sites as opposed to $11.7{\pm}3.3days$ in the control sites. Conclusion: Based on these results, we concluded that CEH accelerates re-epithelialization of partial thickness burn wounds and CEH can be an safe alternative to skin grafts for 2nd degree burns.

• Current Industrial and Technological Trends in Aerospace
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• v.6 no.1
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• pp.65-73
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• 2008

As the system requirements of performance, weight, cost are increasing, the needs of electronic parts which have high performance and efficiency are growing. To satisfy such requirements, demand of high performance and rapid upgraded commercial parts is also increasing compared to NASA or ESA standard parts. Especially, commercial PEM(Plastic Encapsulated Microcircuit) parts are applied in many space programs and research is continuing to broaden its application area. In this paper, concerns and verification trends of commercial PEM parts in space applications are introduced.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2001.10a
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• pp.233-235
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• 2001

Residual stress in the forged parts affects the resistance to mechanical failure, dimensional uniformity, and the service life of the parts. In order to elucidate the development of residual stress in open-die forging process, elasto-plastic finite element analysis was implemented to radial forging process. Super duplex stainless steel SAF 2507 was selected as workpiece material and a series of mechanical tests followed by numerical compensation to deformation heating was conducted to obtain necessary flow data. The residual stress distributions were calculated using commercial 3-D FEM code and the effects of process design were evaluated from selected results.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2005.06a
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• pp.623-624
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• 2005

Micro injection molding is a branch of micro system technology and has been under development for the mass manufacture of micro parts. Enhanced technological products like micro optical devices are entering the market. This paper presents fundamental research on the injection molding technique in micro fabrication. In order to successful manufacturing of micro plastic parts, it is necessary to research for development of micro-injection machine, machining of micro mold, decision of optimum injection conditions and the research for polymer material. Therefore in this study, in order to machining of micro mold, a mold core with microscopic V-shaped groove was tooled by ultra-precise tooling machine. The transcription experiments with a polymer, PMMA resin on the surface of core with Ni plating were carried out and surface profile of injected parts was measured with AFM.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2009.04a
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• pp.55-56
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• 2009

A light guiding plate (LGP) with nanometer-sized patterns was fabricated by injection molding method which employed electrically healed mold and the transcription of injection-molded parts was investigated. A Ni stamper was fabricated using MEMS technology. The Ni stamper was then installed in a movable heated core which is a key part of the mold. Using this mold, injection-molded plastic LGP parts were manufactured at different mold temperatures and the effect of the temperature on the transcription of the parts was investigated.