Effect of Electrochemical Hydrogen Charging Time on Hydrogen Embrittlement of the Hot-Rolled and Accelerated Cooling Treated API X70 Steel

Dong‑Su Bae,Un‑Bong Baek,Seung‑Hoon Nahm,Ilguk Jo 대한금속·재료학회 2022 METALS AND MATERIALS International Vol.28 No.2

This study investigated the effect of the hydrogen charging time on the hydrogen embrittlement of hot-rolled and acceleratedcoolingtreated API X70 steel by using the electrochemical hydrogen charging method. Tensile and V-notch Charpy impacttest were completed for the specimens of hydrogen charged for 0, 2, 4, and 10 h, and then microstructural observation wereperformed. The tensile and yield strength tended to decrease slightly and the total elongation started to decrease rapidly up to2 h charging time and then these gradually decreased with the hydrogen charging time. The post-uniform elongation increasedslightly after the holding time of 2 h due to the occurrence of two-step stress reduction phenomenon and its mechanismhas suggested. The effect of the hydrogen embrittlement on impact absorption energy according to the hydrogen chargingtime were also investigated. The fracture surface of the hydrogen charged ones are generally composed of cleavage fracturesurfaces. It was demonstrated that the external cracks were formed on the outside of tensile tested specimen and the externalshape of the fracture portion was fractured without large elongation at hydrogen charged specimens.

최근 10년간 발생한 신손상 분석

최동은, 김원태, 김용준, 윤석중, 이상철, 김원재 충북대학교 의과대학 충북대학교 의학연구소 2012 忠北醫大學術誌 Vol.22 No.1

연구목적: 신손상은 보통 복부외상 환자의 10% 정도에서 발생하며 비뇨기계에서 발생하는 손상 중 가장 높은 빈도를 차지하고 있다. 신손상 치료의 궁극적인 목표가 환자의 생명을 구하는 것이고, 가능 하면 신조직을 최대한 보존하면서도 합병증은 최소화하여야 하므로 정확하게 평가된 진단을 내려, 혈류 역학적으로 안정된 경우 보존적 요법을 시행하는 빈도는 증가하고 있다. 본 연구에서는 10년간의 신손 상을 분석하여 손상의 원인, 정도, 치료 방법 등을 알아보고자 하였다. 대상및방법: 2000년 2월부터 2010년 6월까지 본원 응급실에 방문하여 신손상으로 진단된 59명의 환 자들을 후향적으로 분석하였다. 결과: 환자의 성별은 남자가 39례 (66.1%)였고, 여자가 20례 (33.9%)였다. 신손상의 원인은 교통 사고가 37례 (62.7%)였고, 낙상이 7례 (11.9%), 외상이 12례 (20.3%), 자상이 1례 (1.7%), 원 인미상이 2례 (3.4% )였다. 손상의 정도는 I 등급이 11례 (18.6%), II 등급이 10례 (16.9%), III 등급이 20례 (33.9%), IV 등급이 10례 (16.9%), V 등급이 8례 (13.6%)였다. 신손상 환자의 치료 는 대증치료가 46례 (77.9%)였고, 신절제술이 5례 (8.5%), 신혈관색전술이 5례 (8,5%), 그외 다른 치료들이 3례 (5.1%)였다. 결론: 신손상의 원인은 교통사고와 외상 등이 가장 많은 비중을 차지했으며, 3 등급의 손상이 가장 많 았고, 치료는 대증요법이 주를 이루었지만, 점차 신혈관색전술이 늘어나고 있다. 앞으로 지역단위로의 추가적인 연구가 필요할 것으로 생각된다.

소규모사업장 용접근로자들의 소음·용접흄·망간 노출에 관한 연구

김동구,문덕환,이채관,박명희,함성애,손병철,김대환,이창희,김휘동,이채언 인제대학교 백병원 2002 仁濟醫學 Vol.23 No.5

Objective : This study was conducted for the purpose of investigating the level exposure of welders to noise, welding fume and Manganese(Mn) related to this process. Methods and Material : All subjects in this study were welders engaged in CO2 arc and coated arc welding process especially in small-scale enterprises classified by type of manufacture of ship building, repairing and of other fabricated metal products, which is located in Gimhae and Milyang of Kyeongsang province in south Korea. Air sampling of welding fume was measured, shipped and analyzed on the basis of national institute for occupational safety and health(NIOSH) method in U.S. and work environment measurement method established in south Korea. To measure Noise in the work environment, Noise dosimeter was used on the basis of work environment measurement method established in south Korea. Result : This study was performed during a period from January, 2000 to December, 2001 and Results were as follows: 1. Noise level measured in this work environment was higher than national criteria for permissible exposure limit on health examinations related to hearing loss. 2. The concentration of welding fume and Mn in manufacture of ship building and repairing was higher than those in manufacture of other fabricated metal products. 3. In conditions of existing in ventilation system installed and operated, the concentration of welding fume and Mn was slightly lower than those of not existing. 4. In conditions of existing in sufficient air supply from out door into the work place relied on natural exhaust system, the concentration of welding fume and Mn was slightly lower than those of in not sufficient. 5. In all subjects, a rate of wearing ear plug and respiratory mask for dust and fume was lower than that of not wearing. Conclusion : According to above results, this study suggests that more positive work environment managements such as the use of portable local ventilation system, the supply of highly qualified personal protective equipment, and consecutive education and training related to health protection should be need to acquire suitable health protection program for welders engaged in small-scale enterprises in Korea.

공단 근로자들의 혈증 중금속 농도에 관한 비교 연구

심운택,이동배,조영채,이영수,윤창규 충남대학교 의과대학 지역사회의학연구소 1991 충남의대잡지 Vol.18 No.1

For the purpose to estimate the exposure levels of heavy metals and to present a basis of occupational health managements to the industrial workers exposed to heavy metals, this study conducted to know the lead and chromium levels of whole blood of industrial workers. The study population were divided into three groups to the exposure levels ; directed exposure group, indirect exposure group and non-exposure group, and the sample number of workers who exposed to lead were 80, chromium were 77, and control group were 31. The contents of lead and chromium were analyzed by atomic absorption spectrophotometer. The results were summerized as follows : 1. Sex distribution of studied group were 77.1 % in male, and 22.9 % in female. Age distribution were 74.4% in 30-49 age group. The work in years were 43.1 % in 5-10 years, 29.8% in 1-4 years. 2. Mean blood level of lead were 33.53㎍/㎗ in direct exposure, 23.84㎍/㎗ in indirect exposure group and 11.77㎍/㎗ in control group. 3. Mean blood levels of chromium were 1.9㎍/㎗ in direct exposure, 1.51㎍/㎗ in indirect groups and 0.95㎍/㎗ in control group. 4. Mean lead levels of direct exposure group was higher in male than female as 36.44㎍/㎗, 27.35㎍/㎗ respectively, but there was no difference in indirect and control group by sex. Mean chromium levels of direct exposure group were higher levels 2.26㎍/㎗ in female than 1.84㎍/㎗ in male, but there were no difference in indirect and control group by sex. 5. The age group of 29 or younger among the direct exposed had high level of lead and chromium as 35.7㎍/㎗ 2.41㎍/㎗ respectively, but that age group had no evident difference in the level of lead and chromium among the indirect exposed and non-exposed.

부산지역 모 공단 및 인근지역 사업체의 산업보건 실태에 관한 조사연구

이동영,손혜숙,이채언,박형종,김대환,엄상화,최성용,유병철 인제대학교 1993 仁濟醫學 Vol.14 No.4

부산지역 공단 및 인근지역 사업체의 산업보건실태를 파악하기 위하여 205개 사업체의 보건담당자를 대상으로 1990년도의 보건실태에 관한 설문조사를 하였다. 조사내용을 일반사항, 보건관리실태에 관한 사항, 작업장 유해환경 및 보호구 지급사항, 건강관련 사항 및 근무조건에 관한 사항 등으로 대별하여 분석ㆍ관찰하였다. In order to obtain the fundamental data for developing more effective and acceptable programs of public health manegement in an industrial complex, 205 health manager in the plants answered the questionaire of the status of industrial health during 1990. The questionaire consisted of general charateristics, health care status, environmental problems, health problems, and others. 72.4% of 205 plants had less than 100 workers. Fabricated metal manufacture was 32.4%. Although Footwear manufacture was 6.4%, the percentage of workers was 33.1% of total workers. The percentage(56.2) of retired women was higher than that(38.2) of men. 51.9% of total plants has recieving group health care services. 85.4% of plants was exposed to noise, 66.5% was exposed to dust. Ear plug and mask were given to prevent noise and dust in 69.2% and 68.6%, respectively. Among 22,299 workers, 618(2.8%) were diagnosed as suspected non-occupatinal disease. 85.9% of them worked on continuously and had their disease treated. The cases suspected for occupational disease was 100 workers. 82.5% of them changed their post. 45% had the compensation for their occuaptional disease. The rate of working: accidents was 2.3%.

HBR과 결합된 간헐폭기공정에 의한 도시하수의 영양소제거 특성

조남운,임봉수,손동훈 대전대학교 산업기술연구소 2000 산업기술연구소 論文集 Vol.11 No.1

In this study, the characteristics of organics and nutrient removal from municipal wastewater with various operation conditions using modified intermittent aeration combined with HBR process was investigated. This system was operated with HRT of 10hr at COD/N 1.96, COD/P 75.3, sludge recycle of 50% to 100% and 18℃ to 25℃. It has been the best operating condition to control, Oxic/Anoxic time ratio setting rate has been set 40min/20min and 100% of sludge recycle, under the conditions such as 2hr HRT at the anoxic reactor, 6hr HRT at the aeration tank. In that conditions, the removal efficiency of BOD, COD, T-N and T-P were 97.5%, 91.7%, 75% and 76.2%, respectively. The SNR(Specific Nitrification Rate) was 3.213mgNH4-N/gMv/hr and the SDNR(Specific Dinitrification Rate) was 4.5mg NO3-N/gMv/hr. T-P removal efficiency is due to biological phosphorus removal and formation of chemical precipitates by pellet. The performance of wasted sludge dewatering in this process is better than wasted activated sludge.

고분자량과 고선형선의 PVA 최적반응 조건에 대한 고찰

진동언,김중현 연세대학교 산업기술연구소 1992 논문집 Vol.24 No.2

High-Molecular weight and high linearity Poly(vinyl alcohol) was prepared by photo-polymerization using ultra violet light and photo initiator (Benzoin Ethyl Ether). The effect of the polymerization temperature and initiator concentration on the molecular weight and linearity were determined. About 1.0×10() molecular weight of PVAc and 0.4×10() molecular weight of PVA by hydrolysis reaction was obtained using optimum condition, 20℃ reaction temperature and 0.01wt% initiator concentration.

산업근로자들의 소음성난청 발생에 관한 조사연구

이동배,조영채,심운택 忠南大學校 環境問題硏究所 1988 環境硏究 Vol.6 No.1

We surveyed 42 industries in Chungchong province for measurement of noise level with hearing test of 1,474 workers from there. 8.1% of total 1,474 workers had their hearing loss at over 45dB in 4000Hz. Mining occupied the highest percentage hearing loss with 11.5%. There showed a tendency of the increased occurrence of hearing loss with the career of service and the age of the workers. And also, C??-dip phenomenon was seen.

Detergent가 NAD의존성 α-glycerophosphate 탈수소효소에 미치는 영향

박수언,이동욱,이희성 중앙대학교 의과대학 의과학연구소 1984 中央醫大誌 Vol.9 No.3

The physical properties and the effects of detergent on the activities of purified NAD-linked a-glycerophosphate dehydrogenase(EC 1.1.1.8, GPDH) from kidney, liver and skeletal muscle of the rat were studied. The activity of this enzyme was measured by the method of White and Kaplan. The enzyme activity of liver (9.65 units/g tissue) was higher than those of other organs, but the highest value of the specific activity was shown in skeletal muscle as 0.058 unit/㎎ protein. These enzymes were purified approximately 167, 286 and 216-fold from kidney, liver and skeletal muscle, respectively, by ammonium sulfate saturation and blue dextran Sepharose column chromatography. These enzymes were composed of two isozymes which have different isoelectric points. Isoelectric points of the two isozymes were 6.5 and 6.7, and the molecular weights were 62,000 and 60,000 daltons. The UV spectrums of the purified enzymes from three organs of the rat showed very simillar pattern. But the representative compounds from three classes of detergents showed different effects on these enzymes. The enzyme of the skeletal muscle was activated by all of the detergents which were studied expect for Triton X-100, whereas the enzymes of the kidney and the liver were not activated or strongly inhibited by all of the detergents. In conclusion, the purified a-glycerophosphate dehydrogenases from the three organs of the rat were the homogeneous proteins out of consideration for physical properties. But the differences in the interaction between enzymes and detergents revealed that there are unsimilarities in the three dimentional structure between the skeletal muscle and those of other two organs inspite of similarities between the enzyme of kidney and that of liver.

지역간 경제력 격차 분석

朴東雲 단국대학교 산업연구소 1989 산업연구 Vol.12 No.-