통합 검색 | Korea Science

김후중;김용모;윤명원
- 한국자동차공학회논문집
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- 제10권6호
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- pp.80-89
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- 2002
The flame structure and soot formation in Acetylene-Air nonpremixed jet flame are numerically analyzed. We employed two variable approach to investigate the soot formation and oxidation processes. The present soot reaction mechanism involves nucleation, surface growth, particle coagulation, and oxidation steps. The gas phase chemistry and the soot nucleation, surface growth reactions are coupled by assuming that the nucleation and soot mass growth has the certain relationship with the concentration of pyrene and acetylene. We also employed laminar flamelet model to calculate the thermo-chemical properties and the proper soot source terms from the information of detailed chemical kinetic model. The numerical and physical model used in this study successfully predict the essential features of the combustion processes and soot formation characteristics in the reaction flow field.
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김광희;조셉비만
- Journal of Advanced Marine Engineering and Technology
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- 제26권6호
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- pp.661-669
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- 2002
Rapid tooling technique enables us to make dies and molds that produce prototype parts with the correct material at a substantially reduced cost and time. In this study, experiments on selective laser sintering of tungsten carbide-cobalt mixture were carried out to find optimal sintering conditions that will be applied to rapid metal tooling. The experiments were carried out within an air, an argon and a nitrogen atmosphere. Coupons of single layer were sintered at various laser powers, scanning speeds and scan spacings. Very severe oxidation took place within an air atmosphere. The oxidation is reduced significantly within an argon and a nitrogen atmosphere. The thickness of the sintered coupons is increased as the energy density, the laser energy Per unit scanned area, is increased. Several multi-layer sintering experiments were also carried out.
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이은표;주준식;유길성;조일제;국동학;김호동
- 방사성폐기물학회지
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- 제2권4호
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- pp.239-244
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- 2004
사용후핵연료 금속전환체의 저장 안정성을 높이기 위해 금속전환체의 주성분인 금속우라늄과 산화 안정화물질로 알려져 있는 Nb을 첨가하여 모의 금속전환체 합금을 제작하였다. 모의 금속전환체 합금을 $200{\sim}300^{\circ}C$ 온도구간에서 순수 산소분위기로 산화시험을 수행하고 무게증가(wt%)를 열중량 분석기(TGA)로 측정하였다. 산화 실험결과 U-Nb 모의 금속전환체는 순수 금속우라늄에 비하여 상당한 산화 저항성을 가졌다. U-Nb 합금의 경우 Nb의 함량 1, 2, 3, 4 wt%에 따라 각각 온도가 $200^{\circ}C$일 경우에는 1.61, 7.78, 11.76, 20.14배 , $250^{\circ}C$에서 1.45, 5.98, 10.08, 11.15배, $300^{\circ}C$에서 1.33, 4.82, 8.87, 6.84배 순수 금속우라늄에 비해 산화저항성이 향상되는 것으로 나타났다. 또한 U-1~4 wt%Nb 합금에 대한 활성화에너지는 17.13~21.92 kcal/mol 로 나타났다.
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