• 한국정밀공학회지
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• 제19권6호
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• pp.23-28
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• 2002

• 소성∙가공
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• 제22권5호
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• pp.269-274
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• 2013

Experiments and numerical simulations of the incremental upsetting test were carried out to investigate void closure behavior and mechanical characteristic of a 1.5wt%C ultra-high carbon steel. The experimental results showed that the voids become quickly smaller as the reduction ratio increases. The simulation results confirmed this behavior and indicated that the voids were completely closed at a reduction ratio of about 40~45% during incremental upsetting. After the completion of the incremental upsetting tests, the process of diffusion bonding was employed to heal the closed voids in the deformed specimens. To check the appropriate temperature for diffusion bonding, deformed specimens were kept at 800, 900, 1000 and $1100^{\circ}C$ for an hour. In order to investigate the effect of holding time for diffusion bonding at $1100^{\circ}C$, specimens were kept at 10, 20, 30, 40, 50 and 60minutes in the furnace. A distinction between closed and healed voids was clearly established using microstructural observations. In addition, subsequent tensile tests demonstrated that complete healing of a closed void was achieved for diffusion bonding temperatures in the range $900{\sim}1100^{\circ}C$ with a holding time larger than 1 hour.

• KIEAE Journal
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• 제12권6호
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• pp.113-121
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• 2012

A hospital is the most important infra-facility of the places which take care of people's body in social environment. There exist several environmental factors in the ways to heal the human body in hospital ward, but this study tried to look into the improvable pleasant sickroom environment with focus on light environment among the factors. In other words, this study aims at the research on proper daylight inflow into sickroom space as basic data for understanding the link between healing environment and natural lighting. In the simulation analysis through this research, this study completed the initial simulation using Autodesk Revit 2011 with focus on two types of individual multi-bed room units of the two general hospitals located in Gwangju City. This study made a simulation analysis of The two multi-bed rooms looking to the west using the weather data on Gwangju district, which is the strong point of ECOTECT2011. Conclusively, looking into the analysis of the simulation model in time of attaching the length of in & outside light shelf, the angle controlling of light shelf, the daylight factor and DA were found to show the tendency to decrease in the numerical value due to the decrease in sunlight inflow as the simulation model moved more toward the room from the window in comparison with the existing analysis of multi-bed rooms. Particularly, this study was able to read that the daylight factor and DA were more decreasing to improve at the light shelf than the existing bedrooms; conclusively, this study judges that the natural lighting simulation analysis could be helpful in improving the healing environment as basic data.