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최병학,이범규,장현수,박찬성,김진표,박남규,김청인,김보미,Choe, Byung Hak,Lee, Bum Gyu,Jang, Hyeon Su,Park, Chan Sung,Kim, Jin Pyo,Park, Nam Gyu,Kim, Cheong In,Kim, Bo Mi 한국재료학회 2017 한국재료학회지 Vol.27 No.8
This study investigated the surface pit corrosion of SS420J2 stainless steel accompanied by intergranular crack. To reveal the causes of surface pits and cracks, OM, SEM, and TEM analyses of the microstructures of the utilized SS420J2 were performed, as was simulated heat treatment. The intergranular cracks were found to have been induced by a grain boundary carbide of $(Cr,Fe)_{23}C_6$, which was identified by SEM/EDS and TEM diffraction analyses. The mechanism of grain boundary sensitization occurred at the position of the carbide, followed by its occurrence at the Cr depleted zone. The grain boundary carbide of $(Cr,Fe)_{23}C_6$ type precipitated during air cooling condition after a $1038^{\circ}C$ solid solution treatment. The carbide precipitate formation also accelerated at the band structure formed by cold working. Therefore, using manufacturing processes of cooling and cold working, it is difficult to protect SS420J2 stainless steel against surface pit corrosion. Several counter plans to fight pit corrosion by sensitization were suggested, involving alloying and manufacturing processes.
최병학,이범규,장현수,전우일,박용성,임재균,이진희,박찬성,김진표,Choe, Byung Hak,Lee, Bum Gyu,Jang, Hyeon Su,Jeon, Woo Il,Park, Yong Sung,Lim, Jae Kyun,Lee, Jin Hee,Park, Chan Sung,Kim, Jin Pyo 한국재료학회 2017 한국재료학회지 Vol.27 No.3
The aim of this study is to consider the effect hydrogen on dezincification behavior of Cu-Zn alloys. The investigations include microstructural observations with scanning electron microscope and chemical composition analysis with energy dispersive spectrometer. The dezincification layer was found to occur in high pressure hydrogen atmosphere, not in air atmosphere. In addition, the layers penetrated into the inner side along the grain boundaries in the case of hydrogen condition. The shape of the dezincification layers was porous because of Zn dissolution from the ${\alpha}$ or ${\beta}$ phase. In the case of stress corrosion cracks formed in the Cu-Zn microstructure, the dezincification phenomenon with porous voids was also accompanied by grain boundary cracking.
벼 재배지 논물의 수질특성과 Chl-a 변동 요인의 통계적 분석
배희수 ( Hui Su Bae ),장현수 ( Hyeonsoo Jang ),황재복 ( Jaebok Hwang ),안승현 ( Seung Hyeon Ahn ),윤종탁 ( Jong Tak Youn ),김욱한 ( Uk Han Kim ),배범수 ( Beomsoo Bae ) 한국환경과학회 2019 한국환경과학회지 Vol.28 No.11
Statistical analysis was carried out to identify the influence on environmental factors between paddy water chemical properties and Chl-a concentration (algae biomass index) using water samples collected in June for 3 years at rice paddy field. As a result of correlation analysis, there was a significantly negative relationships in DO(-0.366) and pH(-0.141). In contrast, significantly positive relationships were founded in COD(+0.431) and TOC(+0.422). According to the result of factor analysis, 3 factors were obtained and indicated that PC1 were Ca, K, Mg cation, PC2 were TOC, T-P, PO<sub>4</sub><sup>3-</sup>-P and DO, and PC3 were T-N and NH<sub>4</sub><sup>+</sup>-N. As a result of linear regression analysis to develop a prediction model for chl-a concentration, the total amount of explanation was 20.6%, PC2 had the greatest influence on the increase of chl-a concentration and PC1 also showed a positive correlation but the PC3 has a negative correlation. In conclusion, carbon and phosporous content are the main factors for the increase algae blooms of rice paddy.
사상체질에 따른 건강한 정상체중 남자의 식이행동유형 비교 연구
신현상,박병주,강미정,이지원,장현수,노환옥,이의주,고병희,이준희,Shin, Hyeon-Sang,Park, Byung-Ju,Kang, Mi-Jeong,Lee, Ji-Won,Jang, Hyun-Su,Noh, Hwan-Ok,Lee, Eui-Ju,Koh, Byung-Hee,Lee, Jun-Hee 사상체질의학회 2010 사상체질의학회지 Vol.22 No.3
1. Objectives: This investigation compares the eating behaviors across normal-weight male groups of different Sasang constitutional types. 2. Methods: We recruited 31 male participants aged 20-35 with BMI 18.5-23. The eating behavior was assessed using Gastrointestinal Symptom Rating Scale (GSRS), Bulimia Test Revised (BULIT-R), Korean Version of Eating Attitude Test-26 (KEAT-26), and Dutch Eating Behavior Questionnaire (DEBQ). 3. Results: 1) Assessments made by GSRS, KEAT-26, and BULIT-R were not significantly different across different Sasang constitutional types. (p<0.05) 2) The Soeum group showed significantly lower BMI and body weight compared to the Soyang and Taeeum groups. 3) The Emotional eating subscale of DEBQ differed significantly across different Sasang constitutional types. (p<0.05) 4) The Soeum group showed a significantly lower Emotional eating subscale score of DEBQ compared to the Soyang and Taeeum groups. 4. Conclusions: The results of this study suggest that emotional factors could influence eating behaviors differently across different Sasang constitutional types, in which the Soeum type is less affected than the Soyang type by emotional states.
최병학 ( Byung Hak Choe ),장현수 ( Hyeon Su Jang ),김형섭 ( Hyoung Seop Kim ),문종언 ( Jong Un Moon ) 대한금속ㆍ재료학회 2017 대한금속·재료학회지 Vol.55 No.10
Age hardening and re-crystallization softening of a type of high entropy alloy, CoCrFeMnNi, was performed to investigate the relationship between microstructure and the property of mechanical hardness. Equiatomic CoCrFeMnNi was produced by casting followed by homogenizing, cold rolling and post heat treatments. TEM analysis revealed that the microstructure of the as-rolled alloy was composed of elongated grains with twin laths and a shear band with fine grains, which exhibited a hardness of 371 HV. Following a 500 ℃ heat treatment the microstructure was composed of nano-twins and nano-grains, which represented age hardening, with 454 HV hardness. The microstructure of 700 ℃ heat treated samples was composed of re-crystallized grains and annealing twins, which represented annealed softening, with 244 HV hardness. The 700 ℃ heat treatment also produced spherical particles of 0.1 m maximum grain size, identified as Cr<sub>23</sub>C<sub>6</sub> type carbide. †(Received March 13, 2017; Accepted May 22, 2017)