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.

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.

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

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.

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.

中炭素鋼 熔接部의 熱處理에 따른 機械的 性質에 관한 硏究

李龍福,金柄旭,康仁燦 弘益大學校 1982 弘大論叢 Vol.14 No.2

Strength of the weld zone is influenced by many complicated factors, such as welding conditions, constraint, materials, etc. Especially, Residual Stress plays an important role for mechanical properties in the weld zone. In this paper, the stress relief effect on the residual stress of the weld zone was examined under various annealing treatment. The results obtained are as follows. 1.Tensile strength on welding decreased 5.7%, 11.4% and 15.3% with increased annealing temperature from 650℃ to 850℃. 2.Absorbed lmpact energy increased in turns of Bond Zone, Base Metal, Fusion Zone and H.A.Z(Heat Affected Zone) and decreased with increasing of the annealing temperature 650℃, 850℃. 3.Reisdual Stress on welding was reduced by the ratio of 65%, 82.5%, 90% with the increased annealing temperature from 650℃ to 850℃. 4.It may be concluded that the best result of the annealing was obtained at 650℃.

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.

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.