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GC250D의 가스분위기 제어질화 공정에서 화합물층의 형성에 따른 표면조도의 변화
정민재,손석원,위재용,이영국,이원범 한국열처리공학회 2024 熱處理工學會誌 Vol.37 No.2
We investigated the changes in microstructure and surface roughness of the compound layer of GC250D gray cast iron, commonly used in brake discs, during gas nitriding. The gas atmosphere of the nitriding process was controlled with a hydrogen partial pressure of 49.5%, and the process was conducted at a nitriding temperature of 520oC with various process times. As the nitriding process time of the GC250D material increased, both the depth of hardening and the thickness of the compound layer increased, with a maximum surface hardness of approximately 1265 HV0.1 was measured. Additionally, the surface roughness increased with the process time. Phase analysis of the compound layer revealed an increase in the proportion of the γ′ phase as the nitriding process time increased. Changes in the formation of the compound layer were observed depending on the orientation of graphite within the material, leading to the formation of wedges. Therefore, the increase in surface roughness appears to be attributed to the uneven compounds, the expansion of the compound layer and wedges formed on the surface during the nitriding process.
정민재,노희정,최지민,전석희,김선종 한방재활의학과학회 2022 한방재활의학과학회지 Vol.32 No.4
This study was conducted to confirm the anti-inflammatory effect of Naetakbaekryeom-san (NTB), and whether it could be another treatment for inflammatory diseases. The NTB water extract was extracted with hot water at 100℃ for 2 hours, concentrated at 80℃ under reduced pressure, and used. After 2 hours of pretreatment with NTB and positive control Bay11-7082, nitric oxide (NO), inducible NO synthase (iNOS), interleukin (IL)-6, IL-1β, tumor necrosis factor alpha (TNF-α) were measured in RAW264.7 cells activated with lipopolysaccharides (LPS) 500 ng/mL. After 2 hours of pretreatment with NTB, the anti-inflammatory effect of NTB was evaluated by measuring nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB) in RAW264.7 cells and 293T cells activated with phorbol 12-myristate 13-acetic acid (PMA) 30 ng/mL. In RAW264.7 cells activated with LPS, NTB at concentrations of 0.1, 0.3, and 1.0 mg/mL showed no cytotoxicity, significantly inhibited NO production and inhibition of iNOS expression. TNF-α cytokine levels was not regulated, but NTB at each concentration inhibited the production of IL-1β and IL-6, and the effect was higher than that of the positive control Bay11-7082 (20 μM). In PMA-activated RAW264.7 cells and 293T cells, each concentration of NBT decreased the NF-κB transcriptional activity, with the greatest decrease at 1 mg/mL. Conclusions These results demonstrated the anti-inflammatory effect of NTB water extracts, but further studies such as comparison of anti-inflammatory effects and antioxidant effects by NTB component, comparison of effects according to extraction solvents, and clinical studies are needed.
영양교사 및 영양사의 지속가능활동의 영향요인 - 확장된 계획행동이론 적용 -
정민재,Chung, Min Jae 한국식품영양학회 2021 韓國食品營養學會誌 Vol.34 No.2
The purpose of this study was to investigate the sustainable practices of nutrition science teachers and dietitians working in school food service operations, and identify the social and psychological factors which affect the overall efficacy of the system. The research model was constructed based on the Extended Theory of Planned Behavior (ETPB) in order to analyze how individual motivation affects the sustainable practices of nutrition science teachers and dietitians. The data were collected through e-mail and postal mail from nutrition science teachers and dietitians all across Korea, and self-administered surveys were conducted. SPSS and AMOS programs were used for statistical analysis. First, the sustainable practices of nutrition science teachers and dietitians were analyzed in 6 different categories. Second, the significant pathways were 6 out of 9 in the ETPB model. Sustainable food service practices in school can contribute to the formation of more a sustainable culture, such as through the encouragement of more healthy eating habits, and higher level of environmental awareness and community awareness. The factors influencing these practices can be applied to the design of improvement programs aimed at increasing sustainable practices.