하중스펙트럼을 이용한 강철도교의 피로해석에 관한 연구

변근주,오진우,김영진 연세대학교 산업기술연구소 1986 논문집 Vol.18 No.1

The objective of this study is to propose the effective stress ranges on steel railroad bridges using the load spectra for actual trains, and to develope a method for prediction of remaining life. The traffic on railroad from Suwon to Cheonan is modeled using 19 cases of loading and probability density curves of stress ranges are derived. Although the three-parameter Erlang curve provide a slightly closer fit, the two-parameter Rayleigh curve is selected for use in this study because it is simpler and provides an adequate fit. Finally. the effective stress ranges are computed using the Rayleigh distribution. These results can be used in predicting the remaining life of steel railroad bridge with S-N curves.

유기용제 노출에 따른 신발제조업체 근무 여성근로자들에서의 후천적 색각이상

변주현,이광영,김영기,고광욱,이용환 대한산업의학회 2001 대한직업환경의학회지 Vol.13 No.3

목적 : 복합유기용제에 노출되는 신발제조업체 근무 여성근로자들에서 유기용제 누적노출량과 후천성 색각이상 발현빈도간의 상관성을 조사하기 위해 본 연구를 실시하였다. 방법 : 신발제조업체 근무 여성근로자들 가운데 유기용제에 노출되는 85명과 유기용제에 노출되지 않는 근로자 88명을 대상으로 조사하였다. 조도가 표준화된 방에서 시력검사와 색각이상 검사를 실시하였다. 작업 부서를 접착, 사상 및 선처리 부서로 나누었고 작업 부서별로 현재노출량과 누적노출량을 구하였다. 결과 : 색각이상의 유병률은 노출군이 대조군보다 통계학적으로 유의하게 높았으며 (P=0.017). 유기용제 노출군 85명 가운데 후천적 색각이상인 청황색 색각이상자가 5명(5.9 %)이었다. 안증상도 노출군이 대조군보다 발생빈도가 높았으며 통계학적으로 유의한 차이를 보였다(P=0.001). 색 혼란지수에 영향을 줄 수 있는 변수들인 연령, 교육기간, 누적노출량 등은 유의한 변수로 나타나지 않았다. 결론 : 유기용제 노출군에서 색각이상의 유병률이 대조군보다 유의하게 높았으며, 특히 유기용제 노출군에서 후천적 색각이상인 청황색 색각이상도 발견되었다. 그러나 유기용제 누적노출량과 색 혼란지수와 유의한 연관성은 발견할 수 없었는데 이는 유기용제의 노출량이 너무 낮았으며, 근로자의 이직률 또한 놓아 누적노출량 계산을 위한 추적기간이 제한되었기 때문인 것으로 생각되며 앞으로 고농도 노출 근로자를 대상으로 연구를 하면 분명한 결과를 얻을 수 있을 것으로 기대된다. Objectives : This study was undertaken to investigate the relationship between color vision defects and occupational exposure to mixed organic solvents in women workers who were engaged in the shoe manufacturing industry. Methods : A total of 173 women workers were involved in this study, 85 of whom were exposed to mixed organic solvents and were defined as the exposed group, and 88 workers comprised the non-exposed control group. The patients were questioned as to their drinking history, the year in which they were exposed and whether they had eye symptoms of blureed vision, eye fatigue, and eye irritation. The exposed workers in the shoe manufacturing factory were engaged in 3 work areas which were pasting, trimming, and cleaning. Their Color vision was assessed using the Hahn's double 15 hue test under standard illumination and their current and cumulative exposure levels were measured. Results : The prevalence of color vision defect was 21.2% in the exposed group and 8.0% in the control group, and the blue-yellow defect was found to be 5.9% in the exposed group. The logistic regression for the acquired dyschromatopsia and color confusion index showed that there were no variables that had significant relationships. Eye symptoms were more frequently developed in the exposed group. Conclusions : There is a possibility of developing color vision defects when workers are exposed to mixed organic solvents. However, the results of the color confusion index showed that there was no significant relationship to the coumulative exposure level, because of the low exposure level and high occupational turn over rate of the workers. Because the workers in the present study were exposed to low level solvents it will be necessary to study workers exposed to higher levels of organic solvents.

환경인자가 무근콘크리트의 피로특성에 미치는 영향

변근주,김영진,이상민,원대연 연세대학교 산업기술연구소 1989 논문집 Vol.21 No.1

In this study, a series of experiments is carried out to investigate the fatigue charateristics of plain concrete in water and seawater which is subjected to cyclic loading with constant amplitude. A total of 200 cylindrical specimens (ø10x20 cm), which were made by readymixed concrete, are prepared for this study. From these series of tests, it is observed that the static and fatigue compressive strength of plain concrete in water and seawater is consideraly lower than that in air. The fatigue strength of the concrete in water is decreased with comparision to that in seawater when stress ratio(??)is less than 0.1, but the concrete in water and seawater has similar fatigue characteristics when the stress ratio is not less than 0.1. And it has been found that the fatigue strength of the concrete in water and seawater is affected by the stress ratio.

허혈성 심질환에서 염증지표에 관한 연구

번정득,권영주,박상호,한대희,이상철,강진환,김명구,심규혁,최병조,온영근,현민수,김성구 순천향의학연구소 2001 Journal of Soonchunhyang Medical Science Vol.7 No.2

Background : Atherosclerosis is the chief underlying cause of ischemic heart disease and there is increasing evidence that inflammation is an important determinant of the development of atherosclerosis. We assessed the levels of inflammatory markers in patients with ischemic heart disease and normal group who has normal coronary angiograms. Materials and Methods : Coronary angiography was performed in 142 patients. 107 patients of ischemic heart disease(stable angina pectoris 58, unstable angina pectoris 30, Acute myocardial infarction 19) and 38 normal control subjects. We assessed the level of inflammatory markers, such as CRP, ESR, fibrinogen and leukocyte. Results : CRP, ESR and fibrinogen values of the patients with stable angina pectoris and unstable angina pectoris were higher than that of normal control group, but there were no statistical significance. Leukocyte value of the patients with unstable angina pectoris(9003.3±701.5/mm^(3)) was significantly higher than that of the patients with stable angina pectoris(6685.5±245.8/mm^(3)) and normal control subjects(6394.3±235.1/mm^(3)). CRP, ESR and fibrinogen values of the patients with acute myocardial infarction were also higher than that of normal control subjects. CRP was 3.88±2.05 mg/dL in acute mocardial infarction group, and 0.29±0.15 mg/dL in normal control subject group(p<0.05). Fibrinogen was 541.6±45.1 mg/dL in acute myocardial infarction group, 321.4±25.6 mg/dL in normal control subject group(p<0.05). Leukocyte was 10942.1±737.6/mm^(3) in acute myocardial infarction group, 6394.3±235.1/mm^(3) in normal control subject group(p<0.05). Conclusions : This study demonstrate that CRP, fibrinogen and leukocyte values of acute myocardial infarction group were significantly higher than that of control group and stable, unstable argina pectoris group. Leucokyte values were significantly elevated in unstable angina group, but CRP values were not in unstable angina group.

철근콘크리트 휨부재의 피로특성에 관한 실험적 연구

김영진,노병철,장세창,변근주 연세대학교 산업기술연구소 1991 논문집 Vol.23 No.2

In recent years, considerable interest has developed in the fatigue strength of reinforced concrete members subjected to cyclic loading for the wide-spread adoption of ultimate strength design procedures, the higher strength materials and the new recognition of the effect of repeated loading on structures such as bridges, concrete pavements and offshore structures. In this study, a series of experiments is carried out to investigate the fatigue characteristics of deformed bars and underreinforced simply supported beams, The 69 reinforcing bar specimens with grade SD30 and designation of D16, D22, D25, and 24 beam specimens with D16 bars are prepared for this study. From these series of tests, it is found that ⅰ) the decrease of the bar diameter results in increased fatigue life, ⅱ) the fatigue life of the bars embedded as main reinforcement within a concrete is longer than that of bars in the air. ⅲ) the fatigue strength of beams at ?? cycles with steel ratio of 0.61% and 1.22% is 64.5% and 63.2% of the yielding strength, respectively. It is concluded that the low steel ratio has no significant effect on fatigue strength of underreinforced beams and the fatigue life underreinforced concrete beams can be predicted conservatively by the fatigue life of reinforcing bar.

ADS알고리즘을 이용한 철근콘크리트 사각형암거의 최적설계

김영진,이상민,이승훈,변근주 연세대학교 산업기술연구소 1990 논문집 Vol.22 No.1

The objective of this study is to optimize the section of RC box culverts and develop a CAD system for drawing. This paper consists of three parts. In the first part, the external load conditions are systematized by using the literatures and specifications. In the second one, the RC box culvert is optimized using the SUMT algorithm. Sizing variables and steel ratio are taken as design variables, and a cost function as the objective function. The stress and side constraints are derived from the Korea Concrete Specification for the ultimate strength design. Finally, a data base and CAD system is developed for the drawing of the optimized section of RC box culverts. The ADS algorithm is applied to one cell box culverts and the results are compared with those of conventional method.

무산소성 운동이 혈청 지질 농도 및 면역세포 반응에 미치는 영향

조영주,변재철,홍석민 한국스포츠리서치 2003 한국 스포츠 리서치 Vol.14 No.2

The purpose of this study was to determine serum lipids and immune responses on the anaerobic exercise. Serum total cholesterol, HDL-C, LDL-C and plasma triglyceride, percentages of WBC and their subsets, natural killer cells were evaluated between before and after the anaerobic power. All subjects were high trained male athletes (19-24 years of age). Results were expressed as mean and standard deviations. One-way ANOVA repeated measure was used to compare the all parameters between before and after the anaerobic power test. All significant differences were set at α=.05. In this study, comparison of anaerobic power(Nm/%BW) was higher in soccer players than ssirum and judo players (p<.05). The percentage of WBC, monocyte, eosinophil and basophil were no significant differences between before and after anaerobic exercise. There were increased on neutrophil, lymphocyte after anaerobic exercise in three groups. (p<.01, p<.001, respectively). Also, there were significant differences on T cell, B cell, NK cell between before and after anaerobic exercise (p<.001).

만성폐색성 폐질환과 위식도 역류질환과의 관계

김영철,오재희,변주남 朝鮮大學校 附設 醫學硏究所 1992 The Medical Journal of Chosun University Vol.17 No.1

In order to investigate the factors influencing the chronic obstructive pulmonary disease (COPD), especially for the relationship between gastroesophageal reflux disease(GERD) and COPD, a case-control study was conducted in chonnam area. Data were obtained from hospital records and interview survey from Jan. to Dec. 1991. Final 64 cases with COPD(case group) were compared with 83 cases of normal lung(control group 1) and 45 cases of non-COPD lung disease (control group 2) The results were as follows. 1. Smoking status, history of adulthood pulmonary infection and frequent history of URI, socioeconomic status and GERD were significantly different between COPD group and control group 1. 2. Drinking status, physical height of the subjects and GERD were significantly different between COPD group and control group 2. 3. If control group 1 was used, odds ratio of GERD and COPD was 5.68(95% confidence interval, 95% CI: 2.59-12.45) and 4.81(95% CI: 1.89-10.53) when adjusted by age and smoking status. 4. If contol group 2 was used, odds ratio of GERD and COPD was 4.22(95% CI: 1.69-10.56) and 4.59(95% CI: 1.64-12.86) when adjusted by alcohol and adulthood respiratory infection status. 5. This results suggested that GERD might play a causative role in the development of COPD.

산업장 소음에 노출된 근로자들의 활동 중 혈압과 심박동수

김영기,차태준,변주현,고광욱,이용환 大韓産業醫學會 2000 대한직업환경의학회지 Vol.12 No.1

목적 : 산업장 근무 근로자들에 있어서 소음 노출이 혈압과 심박동수에 미치는 영향을 조사하고자 하였다. 방법 : 부산시 소재 한 주물공장 근무 근로자로서 소음 작업장에 근무하는 102명에 대하여 1998년 3-6월, 1999년 3-6월에 걸쳐 안정시 혈압과 청력손실정도, 일반적 특성이 조사되었다. 소음노출 정도는 noise dosimeter를 사용하여 오전 8시-오후 4시까지 8시간동안 측정하여 평가하였고, 활동 중 혈압과 심박동수는 ambulatory blood pressure로 오전 8 시-오후 10시까지 30분 단위로 측정하였다. 결과 : 연령과 흡연, 신체비만지수의 영향을 고려하였을 때 저연령층에서 85dBA이상의 고소음에 노출된 군에서 소음과 수축기 혈압간에는 유의한 양의 상관관계가 있었으나, 이완기 혈압과 심박등수에서는 유의한 결과를 얻지 못하였다. 연령의 구분없이 상관관계를 구하였을 때에는 수축기 혈압에서만 소음수준과 유의한 상관성이 있었다. 오전 8시-오후 10시까지 측정한 활동 중 혈압과 심박동수의 일일 변화는 40세미만의 저연령층에서는 심박동수에서만 근무후의 오후시간부터 감소하는 양상이 있었고 수축기 혈압과 이완기 혈압에서는 뚜렷한 변화를 발견할 수 없었다. 40세이상군에서는 수축기혈압과 이완기 혈압, 심박동수 모두 근무 중에는 비교적 높은 값을 유지하다가 오후부터는 감소하는 추세를 보이고 있었다. 각 연령군별 소음노출수준에 따른 활동 중 혈압과 심박동수의 비교에서는 40세미만의 연령층에서만 85dBA이상의 고소음군에서 심박동수가 유의하게 더 높은 결과를 얻었다. 결론 : 저연령층인 40세피만에서 85dBA이상의 고소음에 지속적으로 노출될 경우 수축기 혈압이 증가되어 있을 수 있음을 확인하였다. Objectives : This study was carriel out to evaluate the effects of Industrial noise on blood pressure and heart rate. Methods Resting blood pressure, hearing loss, and general characteristics of the 102 subjects who were engaged In a factory in Pusan were measured from March to June for two years, in 1998 and 1999. With noise dosimeter, noise exposure level was measured from 8 A.M. to 4 P.M. Ambulatory blood pressure and heart rate were also measured every 30 minutes from 8 A. M. to 10 p. M. Results : Controlling for age, smoking, and Quetelet's index, in subjects of under 40 years old exposed to higher than 85dBA, noise exposure and systolic blood pressure had astatistically significant correlation, and the same result was obtained in all subjects. The daily variability of ambulatory blood pressure and heart rate were observed in older than 40 years old group, but only heal·t rate in under 40 years old. Conclusions : The blood pressure and heart 1·ate would be elevated when the workers exposed to noise. And in under 40 years old, the systolic blood pressure was elevated to the workers exposed to higher than 85dBA.

DC Arc로의 유동/열전달 해석 - 용강영역(2)

정순효,변지영,오영주 대한금속재료학회 2003 대한금속·재료학회지 Vol.41 No.8

Heat- and fluid-flow phenomena in the molten steel region in a DC arc furnace were investigated by simultaneous analysis of electromagnetic, flow and temperature fields. It was found that the flow pattern in molten steel was determined by electromagnetic and buoyancy forces rather than the shear force at the melt surface due to the high velocity plasma arc. While the short arc with high current made the hot region beneath the arc expanded, the long arc with high current drove the melt temperature high. And the low arc current led to the non-homogeneous temperature distribution of the melt because the bottom region of the melt was not stirred sufficiently.