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플라즈마 질화처리된 중탄소합금강의 내마모특성에 관한 연구
조효석,노용식,신호강,이상윤 ( H . S . Cho,Y . S . Roh,H . K . Shin,S . Y . Lee ) 한국열처리공학회 1992 熱處理工學會誌 Vol.5 No.4
This study has been performed to investigate into some effects of temperature, gas mixing ratio and time on the optical microstructure, hardness and wear characteristics of medium carbon alloy steel treated by plasma nitriding. The results obtained from the experiment are summarized as follows : (1) Optical micrographs of AISI 4140 steel plasma-nitrided by the double stage technique have revealed that the nitrided layer is composed of the compound layer and the diffusion layer. The variation in temperature at the first stage gives effects, on the formation of compound layer and the growth rate is shown to be relatively fast at 460℃. (2) The thickness of compound layer has been found to increase with increasing nitrogen percentage in the gas mixture and the holding time. It is therefore recommended that a shorter holding time and a lower nitrogen percentage are more effective to produce a tougher compound layer and a diffusion layer only. (3) X-ray diffraction analysis for AISI 4140 steel has shown that the compound layer consist of γ`-Fe₄N and α-Fe and that tough compound layer diffustion layer only can be obtained by the double stage plasmanitriding process. (4) There is also a tendency that the total hardened layer depth increases with increasing temperature, time and nitrogen percentage in the first stage during the double stage plasma nitriding. (5) The wear resistance of plasma nitrided specimens has been found thobe considerably increased compared to the untreated specimens and the amount of increment has appeared to increase further with increasing nitriding temperature, holding time and notrogen percentage of gas mixture in the first stage treatment.
Sursulf처리후 고주파 표면경화된 저탄소강의 경도 및 마모특성에 미치는 Sursulf처리시간 및 고주파 경화 이송속도의 영향
노용식,김영희,이평호,신호강,이상윤 ( Y . S . No,Y . H . Kim,P . H . Lee,H . K . Shin,S . Y. Lee ) 한국열처리공학회 1989 熱處理工學會誌 Vol.2 No.2
This study has been performed to investigate into some effects of the Sursulf treatment time and the traveling speed of surface hardening treatment on the hardness and the wear characteristics by applying the combined heat treating techniques of Sursulf process followed by induction hardening treatment to mild steel. It has been shown that increasing the Sursulf treatment time increases the case depth, but both hardness and wear resistance are not considerably improved. When the combined heat treating technique of high frequency induction heating after Sursulf treatment is applied, an improvement in case depth as well as wear resistance is obtained. In particular, the hardness in diffusion zone is greatly increased due mainly to the formation of martensite and possibly lower bainite. Iron oxides formed during induction heating and subsequent water spray cooling in the outermost part of compound layer may be considered to cause some increases in hardness and wear resistance.
진공포장돈육에 있어서 진공정도에 따른 미생물 생태계의 변화
이신호,이무하,송인상 ( S . H . Lee,M . H . Lee,I . S . Song ) 한국축산학회 1986 한국축산학회지 Vol.28 No.1
Boneless pork chops were vacuum-packaged at the various degrees of vacuum to have 4 different levels (17.6%, 9.8%, 3.1% and 0.4%) of initial residual oxygen in the packages. During the storage period of 21 days at 4℃, changes of reisdual oxygen content, total bacteria count, psychrotrophs count, anaerobes count, lactic acid bacteria count and fluorescent pseudomonads count were investigated. At the end of storage period, all treatments showed no difference in both psychrotrophs and lactic acid bacteria count. However, control gave the highest numbers in total bacteria, anaerobes and fluorescent pseudamauads count. According to results obtained from this study, it appeared that high vacuum-packaging would be more practical method than the other three in terms of microbiological shelf-life.
12주 걷기 운동 강도가 DNA Telomere 길이에 미치는 영향
이신호 ( Lee Shin-ho ),김창한,한태경,김동현,이상화,강현식 ( Kang¸ H. S ) 대한운동사협회 2007 대한운동사협회 운동사대회자료집 Vol.2007 No.-
12주 걷기 운동 강도가 DNA Telomere 길이에 미치는 영향. 본 연구의 목적은 12주간의 걷기 운동 강도에 따른 백혈구 DNA telomere, 활성산소, 지질과산화 및 항산화효소의 활성도의 변화를 알아보는 것이었다. 측정항목은 신체구성변인, 심폐체력, 혈압, 혈액 변인(Glucose, Insulin, 혈중 지질, ROS, MDA, SOD, GPx, telomere length)으로 하였으며, 모든 피검자들을 대상으로 운동 프로그램 운동 전, 운동 후 2회에 걸쳐 채혈하였다. 운동 프로그램에 따른 신체구성 변인의 변화는 BMI, Body fat에서 집단 간에 유의한 차이가 나타났고, 혈액 변인의 변화는 Gucose, TC, LDL-C에서 측정시기별에 유의한 차이가 있었으며, 또한 SOD, GPx에서 측정시기별에 유의한 차이가 있었다. Telomere length, ROS, MDA는 운동 강도는 물론이고 측정시기 간에도 차이가 없는 것으로 나타났으며, 강도×측정시기의 유의한 상호작용 효과도 없는 것으로 나타났다. 이상의 결과를 종합해 볼 때, 운동 강도에 상관없이 규칙적인 12주간의 걷기 운동과 같은 유산소 운동으로 발생한 산화성 스트레스는 백혈구 DNA telomere 길이에 부정적인 영향을 미치지 않는 것으로 판단된다. 또한 이러한 운동은 심폐체력의 증가와 항산화 방어체계의 활성도를 증가시킴으로 건강에 이로운 운동으로 판단된다. Effects of 12 week-walking programs on DNA Telomere length. The purpose of this study was to investigate the effects of two walking exercise programs (one of 50% VO2max and the other of 80% VO2max) on telomere length, free radical, MDA, antioxidant enzyme in healthy nineteen women. Both prior to and after the 12-week walking exercise programs, anthropometric variables (i..e., body weight, body mass index, percent body fat), and cardiopulmonary fitness were measured by using the standardized protocols, Gucose, insulin, blood lipids, ROS, MDA, SOD, and GPx were measured in fasting venous blood samples. White blood cells were isolated from a venous whole blood sample, which were used to extract DNA. The mean of the terminal telomere lengths as an index of telomere lengths was measured by using the Southern blot method. With respect to changes in glucose, lipids, SOD, and GPx concentrations, only time effects were found to be significant with no significant intensity or intensity × time interactions. However, there were neither significant intensity or time effects nor intensity × time interactions in changes of DNA telomere length, ROS, and MDA over the 12-week walking program. In conclusion, the current findings of this study indicate that regardless of intensity, 12 weeks of walking exercises have no harmful effects via excessive oxidative stress on WBC DNA telomere length.
Potassium Sorbate 처리가 계육의 저장성과 저온성 미생물의 분포에 미치는 영향
이신호,한상국 ( S . H . Lee,S . K . Han ) 한국축산학회 1986 한국축산학회지 Vol.28 No.11
This study was carried out to investigate the effect of potassium sorbate on the shelf life and psychrotrophs flora of fresh poultry meat at 4℃. The results were summarized as follows; 1. The shelf life of fresh poultry meat untreated and dipped in 7.5% potassium sorbate was 10±2 days and 15±1 days at 4℃, respectively. 2. The psychrotrophs flora found on fresh poultry meat belong to the genera Alcaligenes, Aeromonas, Achromobacter, Moraxella, Flavobacterium, Staphylococcus, Enterobacreriaceae and Pseudomonas. Pseudomonas was predominant genus in spoiled fresh poultry meat. 3. Potassium sorbate could be useful in retarding growth of spoilage organisms but the effect of potassium sorbate was not found on the psychrotrophs flora of fresh poultry meat.
진공정도가 진공포장 돈육의 이화학적 성질에 미치는 영향
이신호,이무하,송인상 ( S . H . Lee,M . H . Lee,I . S . Song ) 한국축산학회 1985 한국축산학회지 Vol.27 No.6
Changes of physico-chemical properties of pork vacuum-packaged at various degrees of vacuum were studied during 21 days storage at 4℃. During storage, pH of pork showed increasing tendancy regardless of degree of vacuum and the most rapid increase was observed with control. At the end of storage period, pH decreased irrespective of degree of vacuum. By studies on TBA and VBN value, rancidity and protein degradation appeared to be relatively low during 21 days of storage at 4℃. Color of fresh pork did not show differences among treatments at early and late stage of storage while increased rapidly in control and low vacuum treatment at 15 days of storage. From results obtained from high vacuum treatment is better in maintaining pork quality during cold storage than other treatments.