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.

STS304 용접재의 피로거동에 관한 연구

李龍福,鄭鎭成,李柱翰 弘益大學校 科學技術硏究所 1996 科學技術硏究論文集 Vol.7 No.1

In this study, fatigue crack behaviors of STS304 weldment were invesgated when a crack propergated from tensile residual stress region or compressive residual stress region. Crack gowth rates were predicted and compares with experimental result. The experimental results are summarized as follows : 1. For the crack propagation from tensile residual stress region, the maximum residual stress at the crack tip redistributes greater than for the initial residual stress, and the point where the residual stress converted from tension to compression is transferred along the direction of cracking. 2. In the case of fatigue crack propagation from tensile residual stress region, the prediction line of crack growth rate by the initial residual stress declines sharply after middle region and the prediction line by the redistributed residual stress more approaches the experimental results. 3. The fatigue crack from compressive residual stress region has very low fatigue crack growth rate compare with the tensile residual stress region. Because it has low effective stress ratio in compressive residual stress region and it is not almost relaxed compressive residual stress during the cyclic loading. 4. The predicted fatigue crack growth rates considering effects of crack closure are in better agreement with the experimental results, in spite of variation of the residual stress. But there are regions where affected by material properties.

후방압출 공정에서 금형과 제품변형 관계에 대한 연구

이강희,박용복,박태식 公州大學校工科大學生産技術硏究所 1999 論文集 Vol.7 No.-

The die for cold forging gets a very high axial load and radial pressure during processing and hence deforms considerably in the radial direction. This radial deformation of die becomes a important factor influencing the dimensional accuracy of a product. In order to obtain a product with highly accurate dimension. Therefore, it is essential to acquire some information on elastic deformation of the die and the product. The study has been performed for the relation of the deformation between a die and a product in backward extrusion. The strain of the die has been given by the simple experiment using the strain gauges attached to the outer surface of the die. Also the history of the deformation of the die and the product has been given by the experiment and Lame's formula. The results has been compared with the previous another method. The study has given useful results for the deformation history of the die and the product through the experiment and Lame's formula in backward extrusion, which can be applied in the die design for the product with accurate dimension.

Plasmid DNA의 세포전이에 대한 PEI 분자량의 영향

이경만,김인숙,이용복,신상철,오인준 한국약제학회 2005 Journal of Pharmaceutical Investigation Vol.35 No.1

Polyethylenimine (PEI) has been used as cationic polymers for efficient gene transfer without the need for endosomolytic agents. Various kinds of PEIs with different molecular weight were tested in order to investigate the effects of the molecular weight of PEI on the transfection efficiency and cell cytotoxicity. The [3-galactosidase expression (pCMV-13-gal) plasmid was used as a model DNA. Complex formation between PEI and pDNA was assessed by 1% agarose gel electrophoresis method. Particle size and zeta-potential of complexes were determined by electrophoretic light scattering spectrometer. In vino transfection efficiency was assayed by measuring (3-galactosidase activity. Cell cytotoxicity was deter-mined by MTT assay. Particle sizes of the complexes became smaller on increasing molecular weights of PEI and N/P ratios. Surface potential of complexes was increased as the molecular weight of PEI increased. Transfection efficiency of pCMV-[3-gal on the HEK 293 cells was greatest with PEI 25 K system but having the lowest cell viability. PEI with high molecular weight showed higher transfection efficiency and cell viability than PEI with low molecular weight.

미용입 십자형 필렛용접부의 기하학적 피로특성

李龍福,金慶燮 弘益大學校 科學技術硏究所 2000 科學技術硏究論文集 Vol.11 No.-

Fatigue failure modes of symmetrical LOP fillet weldments are dependent on the characteristics of the fatigue crack initiation and propagation from the weld toe or the weld root. In this study, constant amplitude fatigue tests on symmetrical LOP fillet weldments carried out, and fatigue properties were evaluated. Also, an attempt was made to develop the fatigue strength and fatigue life of symmetrical fillet weldments containing lack of penetration. From the result of this study, fatigue crack growth characteristics of symmetrical LOP fillet weldments are found to be affected by the weld geometry, stress range and microstructures of the welding zone.

과학경진대회의 문항과 분석과 학습지도 방안

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

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

初期 缺陷形狀에 따른 表面龜裂傳播 特性에 關한 硏究

李龍福,金鍾鉉,李錫俊 弘益大學校 1990 弘大論叢 Vol.22 No.2

In this study, the diameters and depths of the intial surface crack configuration on the specimen was discharge processed differently and considered about propagation behavior and fatigue lifetime of the surface fatigue crack in each case. The result of this study are Summerized as follow; 1. Under the given constant condition, aspect ratio is regular in surface crack propagation, and early its differenceis large according to the initial surface crack configuration but it shows the same change aspect according to the propagation of the crack. 2. In general, for constand initial crack depths we may expect that initial crack lifetime is increased as diameter of specimen is increased because of relaxation of the stress concentration. Practically, however it is different according to the crack. 3. Early, Surface crack configuration has semi-circle and it has semi-elliptical according to crack propagation. 4. When the initial surface crack aspect ratio is in the range of 5∼6, the initial surface crack is propagated to inner surface under the condition, which ratio is smaller than the range. In the ratio is lager than that range, crack is propagated to outer surface.

알루미늄合金(A5052-0) 熔接部의 疲勞破壤擧動에 關한 實驗的 硏究

李龍福,元光浩 弘益大學校 1985 弘大論叢 Vol.17 No.2

This research deals with Aluminum-Alloy (A5052-0) weldments. In this research the following conclusions are obtained. 1. when the fatique crack in heat affected zone propagates to base metal zone, total life is long in the following order, base metal, unrestrained weld metal, restrained weld metal, and fatigue crack growth rate is low in the same stress intensity factor range in the following order, base metal, unrestrained weld metal, restrained weld metal. 2. when the fatigue crack in base metal zone propagates to heat affected zone, total fatigue life is long in the following order, restrained weld metal, unrestrained weld metal, base metal, and at first time crack growth rate on base metal is higher than in weld metal but lower at the middle of specimen. 3. In E.C.T. specimen and C.C.T. specimen residual stresses in weldments largely act on fatigue behavior and in E.C.T. specimen mechanical properties of bead zone extend total fatigue life.

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.