SM570 QT강 다층용접부에서 저온 균열방비를 위한 예열온도에 대한 연구

고진현,김건형 한국기술교육대학교 2006 論文集 Vol.13 No.1

A preheat temperature to prevent the cold cracking of SM570 QT structural steel weldments made by depositing multiple weld passes in the V-groove with FCAW was evaluated. The diffusible hydrogen content in the deposited weld metals increased linearly with increasing the hydrogen content in the shielding gas. It was confirmed that the cold cracking occurred in the weld specimens with preheat temperature at 50℃ and shielding gas of Ar+20%CO_(2) regardless of hydrogen content. On the other hand, the cracking did not occur in the wledments made with preheat and interpass temperatures at 75℃ and 100℃. Based on this study, it is suggested that the minimum preheat temperature to avoid the cold cracking for SM570 QT steel weld metal is 75℃.

食餌性 蛋白質 水準이 흰쥐의 칼슘 및 燐의 利用率에 미치는 影響

高鎭福,洪鉉順 新羅大學校 1992 論文集 Vol.34 No.1

The effect of dietary protein levels on calcium(Ca) and phosphorus(P) metabolism were studied in 7-month-old female and 14-month-old male rats. Three experimental diets were low protein(10% protein), control(18% protein) and high protein(24% protein). The rats were fed those diets for 40 days. Liver Ca contents of the male and female rats in low protein group were significantly higher than those of control and high protein group. Ca and P concentrations in femur and serum were not affected by thd difference of dietary protein levels. The apparent Ca absorption rate of the male and female rats in high protein group were significantly decreased compared with control group. Increased ingections of dietary protein levels had no effect on P contents of liver among the male and female rats. Apparent absorption rate of P in the female rats was increased with increasing levels of dietary protein, but that in the male rats was not increased.

원자로 압력용기용 SA508 cl.3강재의 서브머지드 아크 용접부에서 입열량이 미세조직과 인성에 미치는 영향

고진현,김세철,서윤석 한국기술교육대학교 2003 論文集 Vol.10 No.1

The microstructures of RPV SA508 class 3 steel multipass weld metals with submerged arc welding process by varying the heat inputs of 2.4kJ/mm and 3.6kJ/mm were investigated by optical and scanning electron microscopes. The microstructures were also compared between as-welded and postweld heat treatment conditions. The relationships between weld microstructures and toughness as well as hardness of weld metals were evaluated. The toughness and hardness of weld metals were enhanced a little in the lower heat input of 2.4kJ/mm. The microstructures of welds made at the lower heat input used in this study consisted of a little higher proportion of acicular ferrite than those of welds made at the higher heat input(3.6kJ/mm), in which unfavorable microstructure to toughness such as grain boundary ferrite and banitic structure were increased.

구조용강 SM520의 플럭스코어드 아크용접 특성에 대한 연구

고진현 한국기술교육대학교 2005 論文集 Vol.11 No.1

In this study, SM520 structural steel welding characteristics with self-shielded and gas shielded flux cored arc welding(FCAW) were compared in terms of mechanical properties, toughness and microstructures. All multipass weld specimens made by both self-shielded and gas-shielded FCAW showed yield and tensile strength of 462~549 MPa and 548~640 MFa, respectively. The impact values of Charpy V Notch weld specimens were also met with the required value of 40J at -20℃. The hardness values of the top area of weldments were higher than those of the bottom area because of higher residual stresses in the near surface. It was found that welding characteristics of SM520 steel by site welding condition of self-shielded FCAW showed nearly equivalent to those by gas-shielded FCAW in terms of sound welds, mechanical properties and microstructure.

Pb-62% Sn 공정합금의 초소성에 관한 연구

배은현,고광진,장현구 成均館大學校 科學技術硏究所 1989 論文集 Vol.40 No.2

The effects of reduction ratio and purity on the superplasticity of Pb-62%Sn eutectic alloys were studied. The alloys of two values of reduction ratio(r=10 : 1, 25 : 1) and impurity content(alloy A : 0.075%, alloy B : 0.216%) were prepared to compare the flow stress and elongation at constant strain rate. Also, the effect of temperature on the tensile behavior and the structural changes of the surfaces were investigated. Larger elongations were achieved for more worked(r=25 : 1) alloys because of their finer equiaxed grains, and for more purified alloy A in which less impurities inhibit the grain boundary sliding. Maximum elongation of 2300% was obtained for alloy A at room temperature, r = 25 : 1 and strain rate, ε˙= 1.4 x 10 exp(-4)/s. Increase in temperature, caused increase in strain rate sensitivity and decrease in flow stress, which explains that atomic accommodation process and grain boundary migration arc more enhanced at elevated temperature.

카드뮴에 의한 흰쥐의 급성 신독성에서 superoxide dismutase의 활성도 변화

이수진,고현철,박정일 大韓産業醫學會 2001 대한직업환경의학회지 Vol.13 No.4

목적 : 카드뮴에 의한 급성 신독성의 병리기전에서SOD의 역할을 구명하고자 본 연구를 실시하였다. 방법 : 1 m9/kg 용량의 Cdcl2를 쥐의 복강내에 1회 주사한 후 1일, 2일, 4일, 8일 및 16일째에 신피질에서 SOD 활성도와 카드뮴 농도를 측정하였다.그리고 신독성의 지표로서 요중 NAG 활성도, 총단백 농도, 24시간 요량 및 카드뮴 농도를 분석 비교하여 다음과 같은 결과를 얻었다. 결과 : 카드뮴 농도는 신피질에서 1일과 2일에,요에서 1일, 2일, 4일에 통계학적으로 유의하게 증가되었고, 요중 NAG 활성도는 1일, 2일, 4일, 총단백 농도는 1일, 4일, 8일에 유의하게 증가되었다.NAG 활성도와 총 단백 농도의 최고치는 각각, 1일과 4일에 관찰되었다. 24시간 요량은 1일에 통계학적으로 유의하게 감소하였다. 요중 NAG 활성도의변화가 요중 총 단백 농도의 변화에 비해 조기에 나타나고 변화율도 컸다. SOD 활성도는 1일에 통계학적으로 유의하게 억제되었고, 8일에는 유의하게 증가된 반면, 요중 총 단백을 제외한 신독성 지표들은 대조군과 비슷한 수준까지 회복되었다. 결론 : 본 연구 결과는 카드뮴이 신피질의 SOD 활성도를 초기에는 억제하고 후기에는 오히려 증가시키며 특히, 초기 SOD 활성도의 억제가 카드뮴에 의한 급성 신독성의 병리기전에서 상당한 역할을 한다는 것을 시사한다. Objectives : To investigate the role of superoxide dismutase (SOD) in the pathogenesis of cadmium-induced acute nephrotoxicity. Methods : Rats treated with a single intraperitoneal injection of cadmium(as CdCl2, 1 mg/kg) were included in the cadmium-treated group ; the control group comprised untreated rats. 24-hour urine samples were obtained prior to sacrifice on days 1, 2, 4, 8 and 16 (N = 10 per group), respectively. The activity of SOD and concentration of cadmium were measured in the homogenates of the renal cortex. Nephrotoxicity indices such as N-acetyl-β-D-glucosaminidase (NAG) activity, total protein, and 24-hour urine volume, and the cadmium concentrations in the urine were measured. Results : The cadmium injection caused a significant increase of cadmium concentra-tion in the renal cortex on days 1 and 2, and in the urine on days 1, 2 and 4. The NAG activities and total protein concentrations in urine were significantly increased on days 1, 2 and 4, and on days 1, 4 and 8, respectively. The peak values of NAG activity and total protein in urine were observes on days 1 and 4, respectively. A significant decrease of 24-hour urinary volume was induced on day 1. Renal SOD acclivity was significantly inhibited on day 1. Finally, on day 8, SOD activity was significantly increased and all nephrotoxicity indices except urinary total protein returned to the control level. Conclusions : These results suggest that cadmium induces initial depression of SOD enzyme activities in the renal cortex followed by a later activation, and that the initial depression of this enzyme plays an important role in mediating the proteinuric injury of cadmium-induced acute nephrotoxicity.

피로와 의료이용, 업무상 사고 및 질병결근

장세진,고상백,강동묵,김성아,정진주,이철갑,강명근,현숙정,조정진,차봉석,박종구 大韓産業醫學會 2005 대한직업환경의학회지 Vol.17 No.4

Objectives: This study examined the relationship of fatigue to medical utilization, occupational accident and sickness absence. Subjects and Methods: Data were obtained from the National Study for Development and Standardization of Occupational Stress (NSDSOS Project, 2002~2004). A total of 30,146 employees categorized within the Korean Standard Industrial Classification and the Korean Standard Occupational Classification were recruited. A structured-questionnaire was used to assess the participants' sociodemo-graphics, job-related factors, health-related behaviors, personality trait, self=perceived fatigue (MFS) and the frequency of medical utilization, occupational accident and sickness absence. Data on medical utilization and occupational accident were confirmed from company health records. Chi-square test and logistic regression analysis were used to elucidate the relationship of self-perceived fatigue to medical utilization, occupational accident and sickness absence. Results: In logistic regression analyses, self-perceived fatigue was associated with medical utilization (outpatient), occupational accident and sickness absence although the strength of the associations was higher in the blue collar workers except for medical utilization. For medical utilization, the white collar worker's adjusted odds ratios of outpatient utilization for workers scoring in the third quartile and the highest quartile, compared to workers scoring in the lowest quartile were 1.50 (95% CI: 1.20-1.87) and 2.16 (95% CI: 1.69-2.75), respectively. The blue collar workers' adjusted odds ratios of outpatient utilization for workers scoring in the second (OR: 1.23, 95% CI: 1.06-1.43), third (OR: 1.42, 95% CI: 1.22-1.66) and highest quartile (OR:1.83, 95% CI: 1.55-2.17), respectively, compared to workers scoring in the lowest quartile were statistically significant. However, no associations were found between fatigue and inpatient utilization for either the white or blue collar workers. The blue collar workers' adjusted odds ratios of being injured for workers scoring in the second, third and highest quartile were 1.41 (95% CI: 1.00-2.00), 1.57 (95% CI: 1.10-2.22) and 2.41 (95% CI: 1.69-3.44), respectively, compared to those scoring in the lowest quartile, but, those of the white collar workers were not significant. There was more likely to an increased risk of sickness absence in workers scoring in the second, third and highest quartile compared to those scoring in the lowest quartile in both white and blue collar workers, but the magnitudes of risk were higher in the blue collar workers than the white collars workers. Conclusion: This result suggests that fatigue is a determinant predictor of medical utilization, occupational accident and sickness absence, and that the pattern of risks for the three outcomes differs according to the occupational type. Some limitations of this study and considerations for future study were also discussed.

부직포활성슬러지법에 의한 하수와 침출수처리에 관한 기초연구

정유진,고현웅,김경순,윤태경,성낙창 한국환경과학회 2003 한국환경과학회지 Vol.12 No.10

In this study, it was performed using submerged nonwoven bioreactor(SNBR) for removal of organic matter, nitrogen and phosphate under different aeration intervals(intermittent aeration). We applied the SNBR at the cheap nonwoven fiber module instead of the expensive membrane. The SNBR was mainly made up of an activated sludge reactor and a transverse flow nonwoven module. with an innovative configuration being in application between them. In case of sewage, the aeration conditions experimented consist of continuous aeration and 60min/60min, 120min/60min, 120min/120min of aeration/nonaeration time intervals, respectively. In case of landfill leachate, the intermittent aeration condition was 120min/120min at aeration/nonaeration. Consequently. a high COD removal rate (about 94%) was achieved in sewage and leachate. Although nutrient removal rate was relatively high without any additional chemicals.

유방암과 섬유선종의 방사선학적 소견 : 유방 단순촬영술과 유방 초음파검사 소견의 비교 연구 Studies on mammographic and ultrasonographic findings evaluation

임한혁,최득린,고은석,이혜경,임철완,이상진,홍현숙,최교창,김영화,박재성 순천향의학연구소 1997 Journal of Soonchunhyang Medical Science Vol.3 No.2

Purpose : To evaluate the utility of mammography and ultrasonography in study of morphologic differential diagnosis between malignant and benign mass. Materials and Methods : Average age of patients with breast cancer was 48.4 year-old, and that of fibroadenoma was 29.4 year-old. The equipments used for examination were MF-159 high frequency mammography(Bennet Co.) and Acoustic image 5200S. We evaluated mammographic findings about breast parenchymal pattern, calcification, margin and size of the mass associated tumor nature, and ultrasonographic findings about shape, height and width, internal homogenicity and echo pattern, wall contour, boundary echo, and posterior shadow in breast mass. Thirty-seven of mammographic findings and 34 cases of ultrasonogreaphic findings in pathologically proven breast cancer and 34 case of mammographic findings and 71 cases of ultrasonographic findings in breast fibroadenoma were reviewed retrospectively. Results : In mammographic study, the parenchymal patterns of breast cancer according to Wolfe classification were NI(16.2%), PI(24.3%), P@(37.8%), and DY(21.6%) and those in fibroadenoma were NI(3.1%), Pl(11.7%), P2(35.2%),and DY(50%). Mammographic findings about presence of calcification were as follows; only calcification(16.2%), only mass(51.3%), and mass with calcification(32.5%) in breast cancer, and only mass(91.2%), mass with calcification(8.8%) in fibroadenoma. The features of mass margins were classified as ill-defined margin(45.9%), well-defined(5.4%), and well-defined with partial spiculation(48.6%) in breast cancer and ill-defined(20.5%), well-defined(73.5%), and well-defined with partial spiculation(5.8%) in fibroadenoma. The mass were grouped by size; 1-2cm(37.8%), 2-4cm(45.9%), and 4-6cm(16.3%) in breast cancer and 1-2cm(79.4%), 2-4cm(17.6%), and 4-6cm (3.0%) in fibroadenoma. On ultrasonographic study, the shape of masses in breast cancer were lobulated(82.3%),oval(14.7%), and round(3.0%),and those in fibroadenoma were lobulated(14.0%), oval(57.7%), and round(18.3%). The cases that the height was longer than width were 32.3% in breast cancer and 0% in fibroadenoma. The findings about homogenecity and echo patterns were as follows; hypoechoic(52.9%) and mixed(47.1%) in breast cancer and hypoechoic(2.8%), hypoechoic(63.4%), and mixed(33.8%) in fibroadenoma. The margin of masses were smooth in 85.9% of fibroadenoma, and irregular in 73.6% of breast cancer. The boundary echoes of masses and decreased posterior echo shadow were seen only in 61.8% and 55.9% of breast cancer, respectively. Conclusion: The margin and calcifications are more clearly delineated on mammography but breast cancer and fibroadenoma, both are more commonly developed in dense parenchymal pattern(P2+DY),and there findings are easily obscured in mammography. So ultrasoography is very useful in these masses evaluation, especially amoung young patients.

정상과 갑상선 종양조직에서 사람 IGF-I 유전자의 발현

김성운,장현하,박상미,김덕윤,우정택,양인명,김진우,김영설,김광원,고석환,홍성화,최영길 경희대학교 유전공학연구소 1993 遺傳工學論文集 Vol.5 No.-

Many of the growth-promoting properties of growth hormone(GH) are mediated by insulin-like growth factor-I(IGF-I), a highly conserved circulating 70-amino acid peptide. Recent studies have shown that multiple mechanisms influence IGF-I gene expression, including transcription from two promoters, alternative RNA splicing, and variable polyadenylation. In thyroid tissue, thyroid stimulating hormone(TSH) and IGF-I are the most possible candidates for follicular cell proliferation and hypertrophy. Actually IGF-I had autocrine and paracrine effect for tissue growing. We prepared thyroid tumor tissue mRNAs using single step method for detecting IGF-I levels according to different tissues, i.e., thyroid adenoma or papillary thyroid carcinoma. We used Northern blot analysis for IGF-I mRNA and RNase protection assay (RPA) for IGF-I transcription start sites. For Northern blot, we used whole human IGF-I cDNA as a DNA probe and for RPA, we used IGF-I exon 1 containing noncoding promoter 1 as a riboprobe. We got good RNA bands from Northern blot analysis around 1 kb (IGF-IA) and 7.5 kb (IGF-IB) region. To clarify the amount of both IGF-IA and IB mRNAs, we measured autoradiographied signal of IGF-I mRNAs bands using densitometer. In IGF-IA signals, there's no change among liver and thyroid tissues, but in case of IGF-IB mRNA bands, the signal was markedly increased in thyroid carcinoma tissues than that of normal thyroid tissue (85% vs 14%). In the study of RPA, all thyroid tissues used the same transcription start sites as those of liver's. We concluded that that this different regulation of IGF-I mRNA was originated from tissue specificity. That meant some tissue specific transcription factor/s were related to tissue IGF-I expression.