SS400강 용접부의 파괴인성치에 관한 연구

국정한,송일규,김봉중,오세용,성호현 한국기술교육대학교 1999 論文集 Vol.6 No.1

In this work, we studied the mechanical properties, structure and the stress intensity factor of the welded areas which were annealed from 500。C to 900。C with an interval of 100。C. The main results are as follow. 1. The as-welded specimen showed the highest tensile strength and yield point. The tensile strength and the yield point decrease as the annealing temperature increased from 500。C to 900。C, and they became smaller in the order of deposited metal, heat affected zone and base metal. 2. The hardness was maximum at about 9 mm from the welding center line, and it decreased drastically in the heat affected zone located between 9∼15mm from the center line. 3. The elongation decreased in the order of base metal, the fusion zone and heat affected zone while it increased as annealing temperature increased. 4. The stress intensity factor(S. I. F.) declined as the length of notch increased and it became smaller in the order of fusion zone, base metal and heat affected zone. This is because fracture toughness is affected by brittlization at heat affected zone as well as the initiation and propagation of cracks.

업종에 따른 연 취급 사업장의 기중 연 농도 및 연 노출 수준 평가

이병국,김용배,리갑수,안현철,김화성,이용진,황규윤,장봉기,이성수,안규동 순천향대학교 산업의학연구소 1999 순천향산업의학 Vol.5 No.1

In order to obtain an useful information for health management and biological monitoring of lead exposed workers, Authors tried to investigate air lead level and the lead exposed level of workers in lead industry according to occupational category. The subjects in our study were 2074 workers in 7 lead-using industries, and study subjects were divided into 4 occupational categories such as storage battery industry (type 1), primary smelting industry (type 2), secondary smelting industry (type 3) and litharge making industry (type 4). Blood zincprotoporphyrin concentration (ZPP), blood lead concentration (PbB) and urinary δ -aminolevulinic acid (ALAU), hemoglobin (Hb), hematocrit (Hct) were selected as the indices of lead exposure. Personal variables such as age, work duration were also collected. The results were as follows. 1. The geometric mean air lead in 9 lead-using industry was 0.1133±4.3120 ㎎/㎥, and that in type 1, 2, 3 and 4 was 0.1038±3.4952 ㎎/㎥, 0.0429±3.4329 ㎎/㎥, 0.1877±2.5123 ㎎/㎥ and 0.9961±5.2910 ㎎/㎥, respectively. 2. The mean ZPP in 9 lead-using industry was 53.1±28.0 ㎍/㎗, and that in type 1, 2, 3 and 4 was 52.0±24.8 ㎍/㎗, 48.0±16.4 ㎍/㎗, 109.8±85.6 ㎍/㎗ and 74.3±37.8 ㎍/㎗, respectively. There was significant difference in ZPP according to occupational category (P<0.01). The percents of lead workers whose ZPP were above 100 ㎍/㎗ in type 1, 2, 3 and 4 were 4.0%, 1.7%, 34.3% and 21.6%, respectively. 3. The mean PbB in lead-using industry was 26.0±11.2 ㎍/㎗, and that in type 1, 2, 3 and 4 was 25.3±11.1 ㎍/㎗, 26.7±8.8 ㎍/㎗, 50.3±15.2 ㎍/㎗ and 36.4±11.0 ㎍/㎗, respectively. There was significant difference in PbB according to occupational category (P<0.01). The percents of lead workers whose PbB were above 40 ㎍/㎗ in type 1, 2, 3 and 4 were 10.4%, 7.7% 71.9% and 43.2%, respectively. 4. While the correlation of Hb corrected PbB with ZPP was higher than non corrected PbB, the correlation of log-transformed ZPP with PbB was higher than non corrected ZPP. 5. Simple linear regressions of PbB and corrected PbB as independent variable with ZPP, log-transformed ZPP and ALAU as dependent variable were statistically significant (P0.01). Coefficient of determination of corrected PbB with other variables was higher than non corrected PbB. As the result of this study, it was suggested that reconsideration of environmental and biological monitoring program was highly recommended for secondary smelting and litharge making industry.

납 폭로 근로자에서 δ-aminolevulinic acid dehydratase 유전형질이 zinc protoporphyrin 및 δ-aminolevulinic acid에 미치는 영향

이병국,황규윤,장봉기,김용배,리갑수,안현철,김화성,이성수,안규동,박종범 순천향대학교 산업의학연구소 1999 순천향산업의학 Vol.5 No.1

The inhibition of δ-aminolevulinic acid dehydratase (ALAD) in the heme synthetic pathway results in increased protophoryphyrin (ZPP) and δ-aminolevulinic acid (ALA) and is responsible for some of toxicological effects of lead. This enzyme is coded by the ALAD gene containing 2 co-dominant alleles. The polymorphisms of ALAD gene may be related to differential effects of lead on ZPP and ALA, ALAD genotype was measured in 975 Korean male lead workers, of whom 897 were homozygous for ALAD1 (ALAD 1-1 genotype) and 96 were heterozygous for ALAD2 (ALAD 1-2 genotype). Blood lead in subjects with ALAD1 was significantly higher than those with ALAD2 (p = 0.01). No difference between ALAD genotypes was found for age, exposure duration, ZPP, ALA, hemoglobin, hematocrit, body mass index, tobacco and alcohol use. After adjustment for possible confounders, ALA and ZPP became significantly elevated in ALAD1 subjects (p = 0.004 and 0.055, respectively). This result suggests that ALAD1 subjects may be more susceptible to the hematotoxicologic effects of lead than ALAD2 subjects.

복합 산화법과 MEMS 기술을 이용한 RF용 두꺼운 산화막 에어 브리지 및 공면 전송선의 제조

김국진,박정용,이동인,이봉희,배영호,이종현,박세일 한국센서학회 2002 센서학회지 Vol.11 No.3

본 논문에서는 양극반응과 복합 산화법( H_2O/O_2 분위기에서 500℃, 1시간 열산화와 1050℃, 2분간 RTO(Rapid Thermal Oxidation) 공정)을 이용한 두꺼운 OPSL(Oxidized Porous Silicon Layer)을 형성하여 이를 마이크로머시닝 기술을 이용함으로써 10 ㎛두께의 OPS(Oxidized Porous Silicon) 에어 브리지를 제조하고, 그 위에 전송선로를 형성하여 그 RF 특성을 조사하였다. OPS 에어 브리지 위에 형성된 CPW(Coplanar Waveguide)의 손실이 OPSL 위에 형성된 전송선의 삽입손실보다 약 2 dB 정도 적은 것을 보여주었으며, 반사손실은 OPSL 위에 형성된 전송선의 반사손실보다 적으며 약 -20 dB를 넘지 않고 있다. 본 연구에서 개발한 산화된 다공질실리콘 멤브레인 및 에어 브리지 구조는 CMOS 공정 후에 사용 가능하며, 초고주파 회로 설계시 편리성과 유용성을 제시하고 있다. This paper proposes a 10 ㎛ thick oxide air-bridge structure which can be used as a substrate for RF circuits. The structure was fabricated by anodic reaction, complex oxidation and micromachining technology using TMAH etching. High quality films were obtained by combining low temperature thermal oxidation (500 ℃,1 hr at H_2O/O_2) and rapid thermal oxidation (RTO) process (1050 ℃, 2min). This structure is mechanically stable because of thick oxide layer up to 10 ㎛ and is expected to solve the problem of high dielectric loss of silicon substrate in RF region. The properties of the transmission line formed on the oxidized porous silicon (OPS) air-bridge were investigated and compared with those of the transmission line formed on the OPS layers. The insertion loss of coplanar waveguide (CPW) on OPS air-bridge was (about 2 dB) lower than that of CPW on OPS layers. Also, the return loss of CPW on OPS air-bridge was less than about - 20 dB at measured frequency region for 2.2 mm. Therefore, this technology is very promising for extending the use of CMOS circuitry to higher RF frequencies.

정상 및 Phenylhydrazine으로 처치한 토끼 적혈구의 Adenosine Deaminase Isozymes의 활성도에 관하여

李鉉國,車鍾希,李奉宰,金良均,李根培 조선의대 1984 The Medical Journal of Chosun University Vol.9 No.1

전기화학적 방법을 이용한 저온형 연료전지용 고분산 Pt 촉매의 제조

윤봉국,최재식,김현수,임태훈,홍성안,이호인 한국공업화학회 2003 응용화학 Vol.7 No.2

Pt was deposited on carbon support by chronoamperometry. The catalytic activity for methanol oxidation was checked by CV (cyclic voltammetry) method. The amount of Pt loading was calculated by integration of I-t curve obtaining the total current used for the Pt deposition. The ECA (electrochemical active surface area) for loaded Pt was calculated from the hydrogen adsorption/desorption peaks in 0.5 M H₂SO₄solution. Pt was deposited on clean carbon electrode surface with various concentration of Pt solution (0.1 mM) was used. As the concentration of Pt increased, the specific catalystic activity of Pt decreased suggesting that, in the electrochemical reaction of Pt ion with electrode surface, Pt particles were smaller and more dispersed in low concentration of Pt solution. With this condition (0.1 mM Pt), Pt was electrodeposited on a commercial carbon support, Vulcan XC-72. Electrochemically loaded Pt catalyst had the higher ECA, and showed higher specific catalytic activity for mathanol oxidation than a commercial Pt/C catalyst.

직업적 연폭로에서 혈중 연량 수준에 따른 선별검사로서의 혈중 ZPP 검사의 타당도

한구석,안현철,김용배,리갑수,김화성,황규윤,장봉기,이성수,안규동,이병국 순천향대학교 산업의학연구소 1999 순천향산업의학 Vol.5 No.1

In order to evaluate the validity of current screening criteria of lead exposure and to provide effective information for the better health management of lead workers, author investigated the interrelationship between blood lead and blood zinc protoporphyrin(ZPP) and evaluate the validity of blood zinc protoporphyrin as the screening test and blood lead as gold standard of diagnostic test. The total of 2245 lead workers (male workers: 1982, female workers : 263) from 12 lead using industries were studied. Blood lead, ZPP, hemoglobin and hematocrit were selected as lead exposure variables. Personal information on sex, age and work duration were also checked. Blood lead was measured with flameless atomic absorption spectrometry (model: Hitachi 8100) using standard addition method. Blood ZPP was measured with portable hematoflurometer (model: Aviv 206). The results obtained were as follows: 1. The mean blood lead of all lead workers were 0.7±14.3㎍/㎗(Male: 31.0±14.4㎍/㎗, Female: 28.2±12.9㎍/㎗), whereas the mean blood ZPP of those were 68.1±47.5㎍/㎗(Male: 63.9±43.7㎍/㎗, Female: 100.1±61.0㎍/㎗). The mean value of hemoglobin and hematocrit of all lead workers were 14.5±1.5g/㎗(Male: 14.7±1.3g/㎗, Female: 12.3±1.2g/㎗) and 45.4±3.6(Male: 46.2±2.8, Female: 39.5±3.1) respectively. 2. Validity of test using blood zinc protoporphyrin as screening test for blood lead levels of 30㎍/㎗ as gold standard of diagnostic test revealed that the highest validity value for male and female lead workers were 50 and 90 ㎍/㎗ of ZPP respectively, showing 50 and 60 ㎍/㎗ of ZPP for all lead workers. While those test for blood lead levels of 40㎍/㎗ as gold standard of diagnostic test revealed that the highest validity value for male and female lead workers were 60 and 90 ㎍/㎗ of ZPP respectively, showing 60 ㎍/㎗ of ZPP for all lead workers, those test for blood lead levels of 50 and 60㎍/㎗ as gold standard of diagnostic test revealed that the highest validity value for male and female lead workers were 60 or 70 and 100 ㎍/㎗ ZPP respectively, showing 60and 70 or 80 ㎍/㎗ of ZPP for all lead workers. 3. Predictive value of test using blood zinc protoporphyrin as the screening test for different blood lead levels of 30, 40, 50 and 60㎍/㎗ as gold standard of diagnostic test revealed that positive predictive value of screening test were decreased by the increase of blood lead level regardless of csreening criteria value ZPP and negative predictive value of screening test were increased accordingly regardless of screening criteria value of ZPP. On the other hand, within same blood lead level as a gold standard positive predictive values were inceased by the increase of screening criteria value of ZPP, whereas the negative predictive value were decreased accordingly by the the increase of screening criteria value of ZPP. 4. The correlation analysis of all lead workers among study variables revealed that CPbB and natural log transformation ZPP(LZPP) were better correlated with other variables and found to be better estimate than PbB and ZPP themselves. The age was correlated with all other variables, but the work duration was not. The correlation analysis of male and female workers among study variables revealed the same results with all lead workers. 5. The slope of simple linear regression of CPbB (independent variable) with ZPP in female workers(3.223)was steeper than in male workers(2.144). That of lead workers with work duration of less than 1 year was steeper than that of lead workers whose work duration was more than 1 year. But there was no slope difference between two groups divided by their work duration of 2 years less and more. The slope of simple linear regression of CPbB lead (independent variable)with ZPP in lead workers whose blood lead were higher than 30㎍/㎗and 40㎍/㎗ were steeper than those whose blood lead were less than 30㎍/㎗ and 40㎍/㎗. 6. The slope of simple linear regression of CPbB (independent variable) with ZPP in lead industries with low mean blood lead were less steeper than those with high mean blood lead. 7. The slope of simple linear regression of CPbB (independent variable) with LZPP in female workers(0.0308was steeper than in male workers(0.0253). That of lead workers with work duration of less than 1 year was steeper than that of lead workers whose work duration was more than 1 year. But where was no slope difference between two groups divided by their work duration of 2 years less and more. While the slope of simple linear regression of CPbB lead (independent variable) with LZPP in lead workers whose blood lead were hogher than 30㎍/㎗ was not steeper than those whose blood lead were less than 30㎍/㎗, there was no slope difference between two groups whose blood lead were less than 40㎍/㎗ and more than 40㎍/㎗. 8. The slope of simple linear regression of CPbB (independent variable) with LZPP in lead industries with low mean blood lead were less steeper than those with high mean blood lead, but the difference was not significant then that of CPbB and ZPP. With above results, it is recommended that the screening criteria value of ZPP should be down to 60-70㎍/㎗ from 100㎍/㎗ for male lead workers and screening criteria of ZPP for female lead workers was all right with current value of 100㎍/㎗. So it is recommended to make different screening criteria of ZPP for male and female workers like the hemoglobin and hematocrit screening criteria. It is also preferable to use CPbB and LZPP rather than uncorrected PbB and ZPP in the evaluation of lead exposure for lead workers.

황토 급여가 거세한우의 발육에 미치는 영향

조원모,기광석,정하연,강수원,김준식,백봉현,김용국 한국국제농업개발학회 2003 韓國國際農業開發學會誌 Vol.15 No.1

본 연구는 거세한우 육성우에 대한 황토 첨가급여가 발육에 미치는 효과를 구명하고자 발육능력, 사료섭취량을 규명한 바 아래와 같은 결과를 얻었다. 전 시험기간 동안의 평균 일당증체량은 대조구와 황토급여구가 각각 0.91㎏과 0.87㎏/day로 대조구가 높은 것으로 나타났지만 유의성은 인정되지 않았다. 사료섭취량은 대조구와 황토급여구 모두 평균 일일 두당 농후사료 섭취량이 2.42㎏이었으나, 건초섭취량에 있어서는 각각 3.02와 3.14㎏으로 황토급여구가 다소 높은 경향으로 나타났다. The study was conducted to investigate the effect of dietary supplements of reddish clay on the growth performance in growing Hanwoo steers. A total of 8 calves was allocated into 2 feeding groups, control(basal diet) and treatment(basal diet plus ad libitim Reddish clay) for Hanwoo steers. This study was carried out for 5 months with a total of 8 calves. The results obtained in the present studies are summarized as follows : Average daily gains throughout the experimental period of 4 months to 9 months of age were 0.91 and 0.87㎏ for control group and reddish clay-supplemented group, respectively, however, no statistical significances were found. Average daily intake of concentrates was 2.42㎏ for each group, while that of hay tended to be higher in reddish clay-supplemented group(3.14㎏) than in control group(3.02㎏).

Research Forum Oral Presentation : The effect of human dentin-derived hydroxyapatite coating on titanium on differentiation of osteoblasts

( Sang Hyun Lee ),( Kye Hee Wee ),( Yang Jin Lee ),( Young Suk Jung ),( Kook Hyun Bong ),( So Won Uhm ),( Sang Chul Kim ),( Hyong Suk Oh ),( Sool Heon Lee ),( Ok Su Kim ),( Young Joon Kim ),( Hyun Ju 대한치주과학회 2009 대한치주과학회 학술대회자료집 Vol.2009 No.1

EXHANCEMENT OF CHANNEL UTILIZATION IN DISTRIBUTED QUEUE

Hyun Kook Kahng,Seong Ho Jeong,Jung Bong Suk 대한전자공학회 1992 JTC-CSCC : Joint Technical Conference on Circuits Vol.- No.-