가스취입에 의한 용융 동 중 납 제거

정성엽,정우광 국민대학교 2002 北岳論叢 Vol.19 No.-

The lead has to be removed for the recycling of copper alloy. The lead cannot be removed from the copper alloy by oxidation. It can be removed by the evaporation because of its high vapor pressure. However, rate information is found on removal of lead from copper alloy. The purpose of present work is to provide a fundamental knowledgs on the removal of lead from the copper alloy by evaporation. Gas injection was made in molten copper alloy, and the evaporation rate of lead was measured. The influence of Ar gas flow rate(2~4 L/min), initial contents of lead(2~4wt%Pb), temperature(1200~1400℃) was investigated based on the thermodynamic and the kinetics. The rate constant is increased with increasing flow rate of Ar and temperature. Though amount of lead removed is increased with higher initial lead concentration, the rate constant is not changed significantly. The activation energy is estimated from the temperature dependence of the rate constant. Also removal of lead from the copper by adding chloride was made for the comparison

한국인 집단에서 VDR, COLIA1 및 ER 유전자의 RELP

안광숙,박선미,김우정 대전대학교 기초과학연구소 2001 自然科學 Vol.12 No.1

본 연구는 골다공증과 관련되어 있는 것으로 알려진 vitarmin D receptor(VDR), collagen |α|(COLIA1) 및 estrogen receptor(ER) 유전자와 골다공증의 연관성을 연구하기 위하여 실시하였다. 대조군과 골다공증 환자를 대상으로 이 세 유전자에 대하여 PCR을 실시하고, 제한효소, Bsml, AccB71, Pvull 및 Xbal를 이용하여 restriction fragment length polymorphism(RFLP)를 관찰하였다. 본 연구에서 한국인 집단은 이 세 가지 유전자의 다형현상과 골다공증 사이에 연관성이 없는 것으로 밝혀졌으며, 한국인에 대한 연구 결과와 다른 민족에 대한 대립인자의 빈도는 유의한 차이가 있는 것으로 나타났다. 이 연구 결과 VDR, COLIA1 및 ER 유전자의 다형현상은 한국인에서 골다공증의 지표로 사용할 수는 없으나, 민족 집단에 대한 유전적 연구에 유용하게 사용될 수 있으리라고 사료된다. In view of the reported association between osteoporosis and polymorphism of the vitamin D receptor (VDR), collagen I a l (COLIAI)- and estrogen receptor (ER) gene, an association study was performed between control group and osteoporosis one for VDR, CQLIM- and ER genotypes in Korean women. The gene polymorphisms were evaluated by restriction fragment length polymorphism analyses, using the restriction enzymes BsmI (VDR), AccB7I (COLIAI), and PvuⅡ and XbaI (ER), respectively. No significant differences in genotype distributions of allele frequencies were observed between &e cases and controls for any of the gene polymorphisms. This study does not support the hypothesis of a major contribution of the VDR, COLIAI or ER polymorphisms to explain variations in osteoporosis. We found the significant difference of genotype distribution at VDR, COLIAI or ER loci in different ethnic populations. These results may be useful for the genetic study of ethnic populations.

혈우병 환자에 동반된 자발성 후복막강 출혈

김광일,김동호,우상민,이석주,김홍성,조인성,윤환중,조덕연,김삼용 충남대학교 의과대학 지역사회의학연구소 1997 충남의대잡지 Vol.24 No.1

Spontaneous retroperitoneal hemorrhage due to hemophilia A with impaired coagulopathy is very rare. Spontaneous retroperitoneal hemorrhage has been recorded as having originated from many retroperitoneal organs and blood vessels, and it may be due to local and/or systemic factors. In the majority of the patients, kidney and adrenal gland were the major site of hemorrhage. The systemic causes of spontaneous retroperitoneal hemorrhage are anticoagulation therapy and chronic hemodialysis. During the course of these treatments, hemorrhagic complications may occur at many site, including the retroperitoneal space. Blood dyscrasias including leukemia, polycythemia, sickle cell trait and hemophilia have been reported associated with spontaneous retroperitoneal hemorrhage. We report a case of spontaneous retroperitoneal hemorrhage occurred in a gemophilia A patient with brief review of literature

기전력법에 의한 Zn-Cd합금의 활동도 측정

정성엽,정우광 국민대학교 생산기술연구소 2002 공학기술논문집 Vol.25 No.-

The E.M.F of the galvanic cell with fused salt was measured to determine the activities of zinc at 700-820K over the entire composition range of liquid Zn-Cd alloys. The cell used was as follows: (-) W│Zn(pure)│Zn^(2+)(KCl-LiCl)│Zn(in Zn-Cd alloy)│W (+) The activities of zinc in the alloys showed positive deviation from Raoult’s law over the entire composition range. The activity of cadmium and some thermodynamic functions such as Gibbs free energy, enthalpy, entropy were derived from the results by the thermodynamic relationship. The comparison of the results and the literature data was made. The liquid Zn-Cd alloy is found to be close to the regular solution. The concentration fluctuations in long wavelength limit, Scc(o), in the liquid alloy was calculated from the results.

CaO-SiO_2-MgO_(sat.)-Fe_tO 슬래그와 용철사이의 V 평형분배비

金抗洙,鄭雨光,趙南敦,崔鉉洙 대한금속재료학회 2002 대한금속·재료학회지 Vol.40 No.4

The equilibrium study has been made on the vanadium distribution between CaO-SiO_2-MgO_ast.-Fe_tO slag and liquid iron over the temperature range from 1540℃ to 1640℃. The vanadium distribution ratios(L_v) were approximately larger than phosphorous distribution ratios(L_p) by a factor of 10∼100 times. The L_v dependence on slag composition and temperature was found to be similar to the case of L_p. The vanadium distribution ratio increases with the slag basicity and Fe_tO content in slag, but decreases with the increase of temperature. A linear relationship was observed between logarithm of (V)/{[V][O]^n} (n=2 or 2.5) and (CaO+0.3MgO)/SiO_2. It is assumed that the vanadium ion is in the form of V^4+ or V^5+ in slag. The mutual function relating the slag components, F_s=0.58(CaO/ SiO_2)+0.025Fe_tO, was introduced to explain quantitatively the influence of slag composition on the vanadium distribution ratio. The log values of vanadium distribution ratio as a function of Fs were derived at the fixed temerature of 1590℃ and 1640℃.

CaO-SiO₂-MgO_(sat.)-Fe_(t)O 슬래그와 용철사이의 V 평형분배비

김항수,정우광 국민대학교 2002 北岳論叢 Vol.19 No.-

Equilibrium experiments have been made to study the vanadium distribution between CaO-SiO₂-MgO_(sat.)-Fe_(t)O slag and liquid iron in the temperature range from 1540℃ to 1640℃. The vanadium distribution ratios were larger approximately by a factor of 100 times than those for phosphorous. The dependence of vanadium distribution ratio on slag composition and temperature is found to be quite similar to that for phosphorous. The vanadium distribution ratio is increased with the increase of slag basicity and Fe_(t)O content in slag. The vanadium distribution ratio is decreased with the rise in temperature. A linear relationship was observed between logarithm of (V)/{[V][O]n} (n=2 or 2.5) and (CaO+0.3MgO)/SiO₂ ratio. It is assumed that the vanadium ion is in the form of V^(4+) or V^(5+) in slag. The function of slag composition, Fs=0.58(CaO/SiO₂)+0.025Fe_(t)O, was introduced to represent the influence of the slag composition quantitatively on the vanadium distribution ratio. Equations for the vanadium distribution ratio using the function of slag composition were derived for 1590°C and 1640℃.

Ar+CH₄ 혼합가스 취입에 의한 용선 탈황 거동

손호상,우성준,정우광 대한금속재료학회 2004 대한금속·재료학회지 Vol.42 No.6

Desulfurization behavior of hot metal was studied by bubbling Ar+CH₄mixture gas through submerged lance. The effects of melt temperature, CH₄partial pressure and gas flow rate on the desulfurization rate of hot metal are discussed. Desulfurization rate was increased by increasing temperature and partial pressure of CH₄. Desulfurization rate of hot metal was described by mixed control of the mass transfer of H₂ gas and [S] through gas and liquid film around the rising gas bubbles and chemical reaction at the interface. It was concluded that the desulfurization of hot metal by Ar+CH₄mixture gas bubbling is controlled by chemical reaction of H₂ gas and [S] at the gas bubble and liquid interface under the present experimental conditions. (Received February 2, 2004)

텔레비전 브라운관 생산업체 남자 근거리 검사작업자에서 시력, 눈물분비기능의 변화

김성아,천병렬,김상우,정상재,이광자 大韓産業醫學會 2001 대한직업환경의학회지 Vol.13 No.4

목적 : 장기간의 근거리검사작업이 굴절력 및 눈물분비량의 감소를 초래하는지를 관찰하고자 3년간추적 연구를 시행하였다. 방법 : 구미소재 일개 TV브라운관 제조공작의 미세한 이상여부를 확인하는 검사작업에 종사하는 남자 근로자 396명 중 정시안, 눈물분비기능이 정상, 40세 미만이며 3년간 추적가능했던 65명을 대상으로 하였다. 시력, 색신 검사 외에 자동굴절력검사, 누액분비검사, 안증상, 근무기간, 실제 검사작업을 수행하는 시간, 일상생활중 TV시청 및 VDT사용시간,작업환경에 대한 불편감, 안경착용여부 등에 대한 설문조사를 시행하였다. 이중 누액분비검사는 쉬르머 I검사로써 1996년과 1998년에만 실시되었으며, 시력및 누액분비기능의 변화가 안증상과 관련이 있는지를 보기 위한 설문조사는 1999년에 시행되었다. 결과 : 32개월간의 구면굴절력의 변화량은 좌우안모두 0.18D(diopter)였으며, 년간 변화량은 0.068D/yr로서 근시화되는 방향으로 진행하였다 20개월간의 눈물의 변화량은 좌안이 6.57 mm/s min, 우안이 6.40 mm/5 min만큼 감소하였다. 30세 이하 연령군과 2년 미만 근무군에서 0.5 D 이상 감소한 빈도가 높았으나 유의한 차이는 없었으며, 조명, 소음,공기에 대한 주관적인 상태와 작업시간외 영상화면사용시간에 따른 차이도 없었다 안불편감의 호소율은 52.3 %이었고 굴절력의 변화, 나안시력의 변화, 눈물분비변화량에 따른 차이는 없었다. 연령, 근무기간과도 관계가 없었고, 조명, 공기, 소음에 대한주관적인 상태에 따른 차이도 없었으나 작업시간외영상화면사용시간이 4시간 이상에서 4시간 미만에 비해 유의하게 높았다. 구면굴절력, 나안시력 및 눈물분비 변화량, 20개월 후의 눈물분비상태, 나이,근무기간, 불량한 조명, 일상생활중 VDT 혹은 TV시청을 독립변수로 하고 안불편감여부를 종속변수로하여 로지스틱 회귀분석을 실시하였다. 유의한 변수는 작업시간외 영상화면의 사용시간으로 4시간 이상인 군이 4시간 미만인 군이 비해 비차비가 10.5(95% 신뢰구간 1. S~73.9)이었다. 결론 : 근거리 검사작업자에서 굴절력 및 눈물분비의 저하가 관찰되었으며, 그 방향은 근시화 및 건성안의 진행방향이었으나, 눈물분비의 저하는 유의한 정도는 아니었고, 근거리검사작업으로 인한 부가적인 근시화의 영향은 관찰되지 않았다. 근거리작업자의 안건강관리측면에서 시력뿐만 아니라, 눈물분비기능, 눈물층의 상태 등을 포함한 안건강프로그램이 필요하다. Objectives : The aim of this field-based longitudinal study was to investigate the effects of near-work on lacrimation and visual function, particularly refractive power. Methods : Our study tracked sixty five male workers for about three years by means of ophthalmologic examinations and questionnaires, to collect data including eye symptoms and subjective work environmental factors. Ophthalmic examinations included visual acuity, Shirmer I test, and autorefractometry. In the first year, the inclusion criteria were ages less than 40 years, no history of ophthalmic diseases, emmetropia (-1.0 ≤spherical refractive power〈 1.0) and normal lacrimation. Results : Over a period of 32 months, spherical equivalents were decreased as much as 0.18D (diopter) for LE(left eye) and 0.18D for RE (right eye). Lacrimation by Shirmer's I test during 20 months were decreased as much as 6.57 mm/5min for LE, and 6.40 mm/5min for RE. Although more myopic-changed workers demonstrated young age (〈30 years) and short work duration (〈2 years), there was no significance to this correlation. Additionally, subjective work environmental factors such as poor illumination, noise, uncomfortable air and daily use of VDT and/or TV were shown to have no significant effect. However, as for eye discomfort, which was reconstructed from several dry eye symptoms, the daily use of VBT and/or TV was a significant variable. According to a logistic regression analysis concerning the effects of refractive power, lacrimation, work duration, poor illumination, and daily use of VDT and/or TV on eye discomfort, only daily use of VDT and/or TV greater than 4 hours displayed OR of 10.5. Conclusions : Myopic changes due to near work were not observed, however lacrimal function was changed in workers. These results suggest that we should consider various factors such as lacrimation, tear film and refraction as well as visual acuity in order to establish an eye care program among near-work performing employees.

Interpretation of Evaporation Behavior of Lead from Molten Copper by the Mass-Transfer Model in Fluid Flow

Woo Gwang Jung 대한금속학회 2005 METALS AND MATERIALS International Vol.11 No.3

Soil Science,Fertilizer & Plant Nutrition ; Available Organic Carbon Controls Nitrification and Immobilization of Ammonium in an Acid Loam-Textured Soil

Woo Jung Choi,Sang Mo Lee,Gwang Hyun Han,Kwang Sik Yoon,Jae Woon Jung,Sang Sun Lim,Jin Hyeob Kwak 한국응용생명화학회 2006 Journal of Applied Biological Chemistry (J. Appl. Vol.49 No.1