모 연취급장 근로자들의 연폭로지표들과 혈압과의 관련성

임상복,김용배,이용진,리갑수,김화성,황규윤,장봉기,이성수,안규동,이병국 순천향대학교 산업의학연구소 1998 순천향산업의학 Vol.4 No.1

In order to investigate the relationship between blood lead with other lead exposure indices and blood pressure in occupationally lead exposed male workers, 629 workers(515 lead exposed workers and 114 non lead exposed workers) in a storage battery factory were studied. Blood lead(PbB), zinc protoporphyrin(ZPP) and urinary δ-aminolevulinic acid(ALAU) were selected as an index of lead exposure. Height and weight were also meaured with calibrated automatic height-weight machine to produce fatness index directly. Personal information on smoking and drinking history were also collected. Blood pressure was mearured by trained nurses with automatic sphingomanometer. All workers took at least 30 minute rest before their measurement of blood pressure. The results obtained were as follows: 1. The prevalence rate of hypertension of lead exposed and non-exposed workers were 3.5% in both group without any difference. 2. There were no differences of systolic and diastolic pressure between groups divided by lead exposure, smoking habit, drinking habit. but the increase of age group made the difference of diastolic pressure, and only differenct of systolic pressure observed in age group of less than 20 and that of more than 40. 3. In pearson's correlation analysis, PbB was correlated with systolic pressure significantly, but not with diastolic pressure. PbB was also correlated with pressure difference(systolic pressure-diastolic pressure). 4. There were no significant increase of systolic, diastolic pressure and pressure difference by the increase of PbB and ZPP grouping. 5. Stepwise multiple regression analysis using systolic pressure as dependent variable and PbB, ZPP, ALAU, age, work duration, smoking habit, drinking habit and fatness (weight*0.9/height-100) as independent variables, revealed that PbB, age, drinking habit and fatness in order were significantly contributed to the dependent variable. 6. Stepwise multiple regression analysis using diastolic pressure as dependent variable and PbB, ZPP, ALAU, age, work duration, smoking habit, drinking habit and fatness (weight*0.9/height-100) as independent variables, revealed that ALAU, age and fatness in order were significantly contributed to the dependent variable. 7. Stepwise multiple regression analysis using pressure difference as dependent variable and PbB, ZPP, ALAU, age, work duration, smoking habit, drinking habit and fatness(weight*0.9/height-100) as independent variables, revealed that PbB, age and fatness in order were significantly contributed to the dependent variable. 8. Logistic analysis of hypertensive conditions with categorized blood lead and other selected categorized independent variables indicated that only age(40> and 40≤) and fatness(1.0> and 1.0≤) were significantly contributed to dependent variable with 95% significant odd ratio confidence interval. With above results, lead exposure in terms of blood lead seemed to be minimally contributed to the raise of blood pressure, and the effect of blood lead was found to be more prominent on the pressure difference than the systolic and diastolic pressure themselves.

時變磁界 測定用 센서에 관한 硏究

이복희,백용현,박형기,정승수,전덕규 경북대학교 센서기술연구소 1992 센서技術學術大會論文集 Vol.3 No.1

복합비타민 유제의 제조와 평가

이문석,조혜영,이용복 한국약제학회 2002 Journal of Pharmaceutical Investigation Vol.32 No.1

Water-lipid soluble multivitamin formulations were widely used to reduce the disease and stress of animals as husbandry has made a remarkable progress in recent. But the efficiency of these formulations is far from satisfactory. So, this study was attempted to develop the physically and chemically stable and useful multivitamin o/w emulsion. Multivitamin o/w emulsion composed of water, soybean oil (10%, vlv), vitamin A, D, E, K, B_2, B_6, B_12 and panthenol. To make a stable o/w emulsion, the egg lecithin (2%, w/v) and glycerin (2.5%, w/v) were used for emulsifier and thickening agent, respectively. The oil in water emulsion system was manufactured by microfluidizer and the physicochemical stability of this emulsion was evaluated. The average particle size and interfacial tension were measured. From the result of interfacial tension tested, critical micelle concentration of the egg lecithin was 0.5% (w/v) and optimal concentration for the preparation of emulsion was 2% (w/v). The mean particle size was about 0.6 μm which was suitable for injections. Short-term accelerated stability as physical stability study was tested by centrifuging and freeze-thawing the emulsion samples. The additions of vitamins resulted in the increment of particle size and reduction of physical stability of emulsion. But it is not an enormous problem for the stability of emulsion. Also, we have performed the long-period preservation stability test for the vitamins. All vitamins were analysed by HPLC. The result of storage under 4℃ and dark conditions demonstrated that all vitamins were maintained stable at least 16 weeks, except for vitamin B_12.

熔接部의 熱處理에 따른 殘留應力 및 破壞擧動에 關한 實驗的 硏究

李龍福,鄭 剛 弘益大學校 1983 弘大論叢 Vol.15 No.2

In this study, picking up a mild steel(SS41) of the carbon steel, a spring steel (SUP9) and stainless steel (SUS304) of the special steel, for the experimental materials, these are welded by CO₂(SS41, SUP9), TIG(SUS304), respectively. After that, the residualstress distribution and fracture behavior at the welded zone are examined according to annealing temperature of the four sections involved as weld. Summarizing of the results in this experiment, the following conclusions are obtained: 1. The residual stress distribution of spring steel (SUP9) is very small in comparison with mild steel (SS41) and stainless steel (SUS304) 2. The removed grade of residual stresses are largest when annealed at 900℃(SS41), 850℃(SUP9), 1000℃ (SUS304), respectively. 3. The tensile strength of heat-affected zones are largest when annealed at 800℃(SS41), as welded(SUP9), 900℃(SUS304), respectively. 4. The impact value of heat-affected zones are largest when annealed at 900℃(SS41), 750℃(SUP9), 1100℃(SUS304), respectively. 5. The best annealing temperatures are at 900℃(SS41), 750℃(SUP9), 1100℃(SUS304), respectively. Then, the residual stress is removed enough and mechanical properties are very suitable.

SM45C鋼 熔接部의 殘留應力에 依한 疲勞破壞擧動

李龍福,金鍾鉉,金相準 弘益大學校 1987 弘大論叢 Vol.19 No.2

Fatigue fracture behaviors of submerged arc welded SM45C steel were investigated when a crack propagated from tensile residual stress region. The experimental values were compared with the values expected by the Forman equation. The results are summarized as follows: 1. When the fatigue crack was propagated the experimental values were found to corresponded to the values predicted by Formane quation. 2. The experimental values in weld metals have a little difference to the values expected by Forman equation. It was assumed that residual stresses were relaxed by repeated tensile loading. 3. The higher stress ratios were, the larger the difference of fatigue crack growth rate always were in the Same stress intensity factor range for each stress ratios. Particularly, these differences of fatigue crack growth rates were smaller in weld metal than in base metal. It agrees with the fact of that the difference of .effective stress ratios for each stress ratios is small.

역할실험실을 위한 새로운 Air Table의 설계 및 실험방법

이계도,이희복,김용복 공주대학교 사범대학 과학교육연구소 1996 과학교육연구 Vol.27 No.1

고등학교와 대학교의 물리실험실에서 사용하고 있는 기존의 기록 타이머는 1차원 운동을 정확하게 기록할 수 있으나 2차원 운동은 기록할 수 없다. 본 연구에서는 1차원 운동뿐만 아니라 2차원 운동을 정량적으로 기록하여 실험결과를 분석할 수 있는 새로운 Air Table장치와 이를 사용한 역학 실험방법을 개발하였다. 본 장치를 사용하여 할 수 있는 실험은 1차원 운동, 운동의 제2법칙, 2차원에서의 포사체 운동, 충격량과 선운동량 보존, 각운동량 보존, 일-에너지 정리 등이다. The conventional recording timer which has been using at the physics laboratory of high schools and colleges gives a precise trace of one dimensional motion. However, it can not be used to get a trace of two dimensional motion. In this study, we have developed new air table and experimental procedures for the mechanics laboratory to analyse quantitatively the data obtained from one dimensional motion, the second law of motion, the projectile the data obtained from one dimensional motion, the second law of motion, the projectile motion in two dimensions, the impulse and linear momentum, the conservation of the linear momentum, the conservation of the angular momentum, and the work-energy theorem, etc.

과학경진대회의 문항과 분석과 학습지도 방안

이용복,배영부 서울교육대학교 과학교육연구소 1996 科學과 數學敎育 論文集 Vol.22 No.-

FCAW 십자형 용접재의 피로거동에 관한 연구

李龍福,吳炳德 弘益大學校 科學技術硏究所 2001 科學技術硏究論文集 Vol.12 No.-

The influence of weld size(l/t) and specimen geometry(a/w) on fatique life and fatique crack growth rate of flux cored arc welded(FCAW) cruciform joints, containing lack of penetration(LOP) defects, has been studied experimentally. It was found that fatique life of the weld joint increases with the larger weld size(l/t) and the smaller specimen geometry(a/w) and exhibits significant variations in low stress region. the crack growth rates are relatively higher with the smaller weld size(l/t) for a constant stress intensity factor range(AK), and are faster with the larger stress intensity factor range. The longer weld leg length appears to be beneficial for the fatigue life in an allowable range of weldment size.

AMS 감축과 쌀 수매정책의 효과

이용기,이용복 영남대학교 지역발전연구소 2003 영남지역발전연구 Vol.32 No.-

WTO 규정에 의한 총AMS(aggregate measurement of supports) 감축제약 조건 하에서, 현행 쌀 산업 약정수매제가 쌀 생산 및 농가소득에 미치는 효과를 분석하였다. 이론적 및 실증적 시뮬레이션 분석결과는 정부의 수매가격 인상이 쌀 생산과 생산자의 소득을 반드시 증대시켜 주지는 않는다는 것을 보여주었다. 이런 결과가 나타나게 되는 주요 원인은 정부 수매가격, 즉 지지가격뿐 아니라 시장가격의 생산 의사결정과 농가소득에 상당히 큰 영향을 미치기 때문이다. 즉, 수매가격의 인상은 단기적으로 쌀 생산을 늘리고 그만큼 생산자의 소득을 증대시키는 효과가 있겠지만 총AMS를 감축시켜야 하는 상황에서 이는 결국 초과공급으로 나타나 시장가격의 하락을 초래하여 쌀 생산과 소득증대에 악영향을 미치게 되는 것이다. 특히, 최근 몇 년의 상황처럼 쌀의 재고 누적과 초과공급이 존재하는 상황에서 그 악영향은 더욱 명백해진다. 국내·외의 변화된 시장환경으로 정책효과는 별로 거두지도 못하면서 국제사회로부터 보호주의 정책으로 강한 비난의 대상이 되고 있는 현행 약정수매제도는 재검토되어야 할 시점에 와 있다. WTO에서 녹색정책(Green Box)으로 분류되고 있는 공공비축제로 전환될 필요가 있다.

SS41村 熔接部의 疲勞龜裂傳播에 미치는 殘留應力의 影響

李龍福,金鍾鉉,趙顯億 弘益大學校 1988 弘大論叢 Vol.20 No.2

In this study submerged arc welded the welding structural steel(SS41) was selected as an application model. On condition that stress ratios were 0.5, 0.3, 0.05, the relaxation of the residual stress was measured according to the number of repeated cycles, and the experimental values were compared with the values expected by the superposition of residual stress relaxation. The result are summarized as follows : 1. Welding residual stress is conspicuously reduced depend on the increase of repeated cycles, that is, the effect of welding residual stress on the crack propagation is gradually reduced with the increase of repeated cycles. 2. The error bet ween the experimental values and expected values which are considered only initial residual stress can be reduced by consideration of residual stress relaxation according to repeated cycles. The expected values depend on this method agree to experimental results of fatigue fracture behavior. 3. In case of welded metal, unlike base metal, rate of initial crack ropagation don't show up large difference because the difference of effective stress ratio(Reff) is decreased very much by addition to tensile residual stress.