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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.
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.
Temperature-dependent performance of the erasure machine
정민재,김범준 한국물리학회 2022 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.80 No.9
Interaction strengths in spin systems can be estimated from the maximum likelihood estimate (MLE) method based on information of spin configurations. The application of the standard MLE method has been known to face serious problems for large data sets since it demands huge computation cost. We test the performance of the erasure machine, which has been recently proposed to overcome such drawbacks of MLE, for the Sherrington–Kirkpatrick model and two-dimensional Ising model. In this paper, we focus on how the performance of the erasure machine varies with the temperature and find that it exhibits the best performance not at criticality, but at somewhat higher temperature. We also attempt to explain such temperature-dependent performance of the erasure machine.
Memory 소자 응용을 위한 BST(Ba_xSr_1-_xTiO_3) 강유전체 박막과 전극과의 계면특성
정민재,조정희,홍석민,김호건,김옥경 漢陽大學校 工學技術硏究所 1997 工學技術論文集 Vol.6 No.1
BaxSr1-xTiO3 powders were prepared by changing stoichiometry of Ba and Sr. After they were calcined and sintered at 1,200℃ and 1,300℃ respectively, BST sputtering targets were made in 3inch mould. For MIM structure capacitors. Pt-based structures such as Pt/TiN/SiO2/Si, Pt/Ti/Si3N4/Si, Pt/SiO2/Si, Ru/SiO2/Si and Ru/Si3N4/Si were used for bottom electrodes, and subsequently, the BaxSrl-xTiO3 thin films were sputtered on them. After the analysis of their structures by XRD, Al was evaporated on the BST films for MIM capacitor. We found that the structures of the films showed good crystallinity above 550℃ from the results of XRD measurements. The largest dielectric constant of films was obtained with 0.7mol% of Ba. The electric properties of the capacitors were very good with Pt/TiN/SiO2/Si electrodes.