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.

SICM616鋼 熔接部의 疲勞龜裂傳播速度에 있어서 殘留應力의 效果에 關한 實驗的 硏究

李龍福,金豪敬 弘益大學校 1984 弘大論叢 Vol.16 No.2

The following conclusions can be drawn from comparisons of fatigue crack growth rates in the weld metal and base metal of high strength steel. 1. Crack growth rates in weld metal are slower than those in base metal at low ΔK. 2. Crack growth rates in weld metal and base metal are almost identical at R=0.5. 3. The lower the stress ratio, the higher the residual stress effect, and higher stress ratio cause greater residual stress relaxation.

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.

장상피화생과 Helicobactor pylori와의 상관 관계에 관한 연구

이복희,김대수,이현숙,진영주,윤세진,송형근,성노현,정현용,이동호 충남대학교 의과대학 지역사회의학연구소 1994 충남의대잡지 Vol.21 No.2

In 1965 Lauren divided advanced gastric carcinoma into two main types-namely, "intestinal" and "diffuse" type carcinoma, which differ not only morphologically but also in their clinical and epidemiological characteristics. Moreover, a different histogenetic process has been postulated by many authors that intestinal type gastric carcinoma might arise from areas with intestinal metaplasia. Since Warren and Marshall reported the presence of Helicobacter pylori in the stomach in 1983, strong evidence has been obtained that there is a close relationship between Helicobacter pylori and chronic gastritis, atrophic gastritis, intestinal metaplasia, and intestinal type gastric carcinoma. To study the relationship between intestinal metaplasia and Helicobacter pylori infection, we performed gastroscopic biopsies and CLO tests taken from patients with epigastric pain. Only 87 patients with macroscopically suspected antral gastritis were included. The prevalence of intestinal metaplasia in gastric antral biopsies increased from 33.3% in the age group<30 years to 63.6% in the age group 60 years. When all patients were divided into two age groups-namely, (i)<50 years(n=41) and (ii)≥ 50 years(n-=46), intestinal metaplasia was found significantly more often in patients ≥ 50 years. ((i) 39.2%, (ii) 54.3%, p<0.0001). The prevalence of Helicobacter pylori in gastric antral biopsies decreased from 66.7% in the age group<30 years to 62.5%, in the age group in the age group 50 to 59 years. When all patients were divided into the same two age groups-namely(i)<50 years and (ii)≥50 years, the prevalence of Helicobacter pylori did not differ between two groups in a statistically significant way. The mean age of intestinal metaplasia positive patients who were also Helicobacter pylori positive was 48±11.0(mean±S.D.)years, whereas the mean age of intestinal metaplasia positive patients who were Helicobacter pylori negative was 52±9.7(mean±S.D.)years. In conclusion. although our data do not prove a causal relationship between Helicobacter pylori infection and the histogenesis of intestinal metaplasia, we suggest that Helicobacter pylori plays an important role in the development of intestinal metaplasia in the gastric mucosa. Whether Helicobacter pylori has to be present at all times during this process or is only necessary as a 'trigger', needs further research.

고능률 소형 전자석에 의한 자왜 및 자기이방성 측정

이용호,신용돌,김병걸,민복기,송재성 全北大學校 基礎科學硏究所 1994 基礎科學 Vol.17 No.-

자왜 또는 자기이방성의 측정에 사용되는 전사석의 여자전류를 측정에 필요한 수초간만 흘려서 에너지 소모 및 측정시의 최대난점인 시료의 온도변화의 문제를 극소화하였다. 따라서 전자석의 냉각장치는 생략되고 크기와 전원의 용량도 극소화되었다. 공기간격 22㎜, 자극의 단면적 40 × 25㎟에서 0.5 T의 자장발생에는 180 W의 전원으로 족하였다. 시료의 자왜와, 자기이방성에 의한 토크를 전기용량센서에 의하여 측정하여 10^-8의 자왜분해능과 1 nJ의 토크 분해능을 얻었다. 0.02× 0.8× 10㎟의 연자성 리본의 형상이방성을 이용하여 이방성 측정시의 토크값을 교정하였다. A high efficiency small electromagnet(22㎜ air gap and 40 × 25㎟ core's cross section) suitable for measuring magnetostriction and magnetic anisotropy was built. The magnet could be miniaturized by reducing the measuring space and time. The excitation current of the electromagnet was supplied for only a few second of small. An 0.5 T magnetic field was generated with 180 W power consumption. The values of magnetostriction and magnetic anisotropy were measured with a very sensitive capacitance cell with resolution of 10^-8 and 1 no. The torque was calibrated using a soft magnetic ribbon's shape anisotropy.

용접방법에 따른 하중전달 십자형 필렛 용접부의 피로특성

李龍福,吳炳德 한국공작기계학회 2002 한국공작기계학회 춘계학술대회논문집 Vol.2002 No.-

In this study, it was investigated about endurance limit and fatigue behavior of load carrying fillet welded cruciform joints according to welding methods of SMAW, SAW, MIG and FCAW commonly using for welding structures in present. Endurance limit carried out highly in the order of SMAW, MIG, SAW, FCAW and fatigue crack propagation ratio carried out lowly in the order of SMAW, MIG, FCAW, SAW. By these results, it is needed to use SMAW or MIG welding methods for welding structures with small welding capacity and SAW or FCAW methods for large welding structures after due consideration about economic gains and operation efficiency of welding. Fatigue crack propagation ratio is more effected by strength of welding materials than endurance limit of welding materials according to welding methods.

강 봉 맞대기 용접부의 피로 및 파단 특성

이용복 한국공작기계학회 2009 한국공작기계학회 춘계학술대회논문집 Vol.2009 No.-

SM45C steel rods using generally for machine components was selected and welded by butt-GMAW method for this study. And then it was studied about characteristics of fatigue behavior and fracture surfaces by rotary bending test. Fatigue strength in weld zone presents highly in order of the boundary between deposited metal zone and heat affected zone, deposited metal zone, heat affected zone. The region of infinite life by Haigh diagram presents highly in order of the boundary between deposited metal zone and heat affected zone, deposited metal zone, heat affected zone. Fatigue cracks in unnotched specimens of base metal and weld zone introduces simultaneously from extensive out-side of circumferential cross-sections and propagates to the other side indicating beach markings and dimples according to consolidation of fatigue cracks. Fatigue cracks in all of notched specimens introduces simultaneously in out-side of circumferential cross-sections by high stresses and propagates to center of it indicating beach markings.

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.

Al 2024-T4 熔接部의 殘留應力이 疲勞破壞擧動에 미치는 影響

李龍福,金鐘鉉 弘益大學校 1986 弘大論叢 Vol.18 No.2

Fatigue fracture behaviors were investigated by using the TIG welded aluminum alloy such as high-strength Al2024-T4 which are widely used in aero-space industry. The fatigue crack propagation was closely examined in both from tensile residual stress region towards compressive residual stress region and from compressive residual stress region towards tensile residual stress region. The experimental results are summarized as follows: 1. In case of fatigue crack propagation from tensile residual stress region, the values predicted by the Forman equation were found to be exactly corresponded to the experimental values. 2. In case of fatigue crack propagation from compressive residual stress region, the Forman equation was found improper to apply directly, but the equation was found proper, if the stress ratio was modified to zero. 3. It was found that crack propagation speed at tensile residual stress region was greater in restrained welding than in unrestrained welding, While crack propagation speed at compressive residual stress region was the same, both restrained welding and unrestrained welding.

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.