高 망간 耐熱鋼에 있어 크롬 擴散에 對하여

千炳善 충남대학교 공업기술개발연구소 1975 工業技術開發硏究所論文集 Vol.2 No.2

One of the most serious problems in heat resistant alloy steel would be the control of accelerated corrosion caused by using it at high temperature. In this paper were studied chromium diffusion coating (chromizing) by powder method for austenitic heat resistant alloy used for boiler or gas turbine. When Nickel free austenitic heat resistant steel containing cobalt 2% was chromized by a mixture of chromium powder, alumina-powder and ammonium chloride. The thickness of the layer was limited to a small value mainly because of low diffusion constant of chromium in this alloy. The maximum depth of the layer on alloy steel obtained by powder method was 50 microns and surface chromium concentration was 69 wt. % and Activation energy at 1,200℃ was 37.4 Kcal/mole.

高 망간 耐熱鋼의 熱處理에 의한 析出物에 관한 硏究

千炳善 충남대학교 공업기술개발연구소 1976 工業技術開發硏究所論文集 Vol.3 No.1

High Manganese steel with Mn, Cr, Co and Ti were studied mainly by micorography on the isothermal carbide precipitation after solution treatment. High Manganese austenite stainless steel has been developed for the high temperature application especially in boiler tubes. It was found that the hardness of the steels increased with increasing of the Titanium content and the solution temperatures. This hardness is due to dispersion hardening caused by undissolved Titanium-carbide particles. The major hardening phase was TiC and M_23C_6.

工業敎育大學의 實驗實習施設 共同活用 및 運營에 關한 硏究

尹錫天,牟相榮,權五憲,千炳善,周赫鍾,李永臣,金健中,羅聲雄,洪錫雨,吳德成,盧泰天 충남대학교 공업교육연구소 1983 論文集 Vol.6 No.2(A)

The College of Engineering was specialized to have a sole function for supplying technical high school teachers in 1977 and referred to as the College of Industrial Education according to the Government's policy. The economic impact mainly due to the oil-crises caused a severe problem to this college, namely discrepancy of supply to demand scale. Accordingly the number of student enrollment was to be fluctuated from 479 in 1979 through 800 in 1979 and 900 in 1980 to 430 in 1981. And the engineering departments have been attached to this Engineering Education College since 1981. These circumstanses met singnificant inefficiency in facility operation. This program aims at providing an overall relocation of the college facilities and preparing the practical system to make the joint-operation possible taking into account circulation, academic stream, budget, maintenance, etc. However this study could not get optimal spacing but some trade-off, considering the current situation.

高 Mn鋼의 冷間加工에 의한 物性的인 變化와 機械的性質에 관한 硏究

조성석,千炳善,李揆暢 충남대학교 공업교육연구소 1981 論文集 Vol.4 No.1

Austenite series high Mn-steels have a good wear-resistance but its preferred precipitation along the grain-boundary is the weakest point. Authors have studied on the prevention of preferred precipitation along the grain-boundary by the cold-working. Cold-working ranging from 10% to 30% was carried out in the liquid nitrogen atmosphere. Wear-resistance by cold-working was increased in 0.06-0.2㎎/113㎟ than the age-hardened materials. This can be explained by the effect of cold-working which induces the phase-transformation and cause to fine the grain-boundary.

급속응고 Al-20Si-5Fe-2x(x=Ni, Cr or Zr) 합금의 미세조직 및 기계적 특성

김탁수,千炳善 대한금속재료학회 2002 대한금속·재료학회지 Vol.40 No.8

The microstructure and mechanical properties of the gas atomized and extruded Al-20Si-5Fe-2x (x=Cr, Zr or Ni) alloys were evaluated. The alloy powder was degassed under different vacuum levels in advance of the extrusion. It was shown that the addition of a quaternary element resulted in the formation of very fine particles that contributed to the improved mechanical properties of the alloys, especially at elevated temperatures. Of these additions, nickel was found to be the most effective in increasing the UTS of the alloy both at room and elevated temperatures. Degassing the rapidly solidified powders under better vacuum improved the properties further.

기계적으로 밀링된 나노결정 Al-14wt%Ni-14wt%Mm 합금 분말의 열 안정성과 미세조직

홍순직,이윤석,천병선 대한금속재료학회 2003 대한금속·재료학회지 Vol.41 No.10

Mechanical milling has been performed for Al-14 wt%Ni-14 wt%Mm(Mm=misch metal) alloy powders rapidly solidified by the gas atomization method. The microstructure, hardness, and thermal stability of the powders were investigated as a function of milling time using X-ray diffraction(XRD), transmission electron microscopy(TEM), Vickers micro-hardness tester and differential scanning calorimetry(DSC) methods. In the early stage of milling, a cold-welded layer with a fine microstructure was formed along the edge of the milled powder (Zone A). The interior of the powder remained unworked (Zone B), resulting in a formation of two-zone microstructure. With increasing milling time, the nanocrystallite size decreased gradually reaching a size of about 10-15 nm and the lattice strain increased reaching a maximum value of about 0.7% after milling for 200 hours. The microhardness of the mechanically milled powder was 132 kg/㎟ after milling for 72 hours, and it increased to 290 kg/㎟ after milling for 200 hours because of the presence of fine nano structured phases.

일개 대학병원근무자들에서의 인플루엔자 예방 접종 순응도 관련요인

정희진,손장욱,최선주,엄중식,우흥정,천병철,김우주,박승철 대한감염학회 2004 감염과 화학요법 Vol.36 No.4

목적 : 병원근무자에서의 인플루엔자 예방 접종은 병원내에서 인플루엔자 전파를 막기위한 수단으로 적극 권장되고 있으나 매년 인플루엔자 백신을 접종하는 병원근무자들은 소수에 지나지 않는다. 본 연구는 병원근무자들에서의 인플루엔자 예방 접종률을 향상시키기 위한 목적으로 첫째, 백신 접종자에서의 인플루엔자 백신 접종 계기를 알아보고 둘째, 인플루엔자 백신접종의 장애요인을 분석하여 그 문제점을 해결하는데에 목표가 있다. 재료 및 방법 : 서울 1개 대학병원의 병원종사자들을 대상으로 1999년 10월 1개월에 걸쳐 인플루엔자 예방 접종을 하도록 한 후 2000년 3월에 접종군과 비접종군을 대상으로 구조화된 설문지를 이용한 설문조사를 실시하였다. 백신 접종군을 대상으로 백신접종의 동기(que to action), 비접종군을 대상으로는 접종에의 장애요인(barrier) 등을 조사하였다. 이 외에도 양군을 대상으로 인플루엔자에 대한 지식 척도, 인플루엔자 백신으로 기대되는 효과(benefit)등에 대한 설문조사를 시행한 후 정답률을 조사하였다. 결과 : 1) 설문 조사에 응한 총 수는 309명으로 간호사가 60% 이상이었다. 백신접종군은 평균연령, 평균 근무연수가 비접정군에 비하여 유의하게 길었으나 성별, 직종별 분포는 양 군간 차이가 없었다. 2) 인플루엔자 예방 접종의 필요성에 대한 지식정도에 있어 접종군의 934%가 그 필요성을 잘 인식하여 비접종군의 779%보다 유의하게 높았으나 예방 접종이 필요한 구체적 이유에 대한 정확한 이해는 접종군 113%, 비접종군 119%에 불과하였다. 3) 인플루엔자 예방 접종을 받은 의료인들의 행동계기는 ‘감염관리실의 홍보’와 ‘주위사람들의 권유’에 의한 경우가 26.9%, 21.6%로 가장 많았고 본인이나 가족, 친구들을 통한 일종의 감지된 위협 때문에 접종한 경우 31명(186%)의 순이었다. 4) 비접종자들에서 예방 접종을 시행치 않은 가장 흔한 이유는 ‘업무에 바쁘고 시간이 없어서’라는 항목이었으며(37.3%) 특히 의사 집단에서는 이러한 이유가 68.8%로서 압도적으로 많았다. 간호사나 기타 직종에 종사하는 직원들의 경우는 자신의 건강에 대한 확신이 30%내외에 달하였고 예방 접종 자체의 효과에 의문을 갖는 경우도 직종에 따라 6.3-29.7%에 달하였다. 결론 : 병원근무자에서 인플루엔자 예방 접종률을 향상시키기 위해서는 백신 접종의 장애물(효과의 의문, 부작용)을 효과적으로 제거하고 인플루엔자 백신의 필요성과 효과를 인식시키기 위한 교육과 함께 시간, 공간상의 제약을 배제할 수 있는 접근성의 문제를 해결하여야 할 것으로 사료된다. Background : In spite of yearly recalls, influenza immunization rate among healthcare workers (HCWs) remained low in Korea University Guro Hospital. This study was conducted to identify the causes of non-compliance against influenza immunization and to analyze the barrier factors for the immunization. Materials & Methods : Questionnaires were distributed in March of 2000 at Korea University Guro Hospital. We evaluated factors associated with acceptance of influenza vaccination and opinions regarding influenza prevention (knowledge about influenza vaccination efficacy, que to action in vaccinee, perceptible benefit, barrier to vaccination). Results : 309 completed questionnaires from HCWs were returned. Mean age and mean duration of work in hospital were higher and longer among vaccinee than non-vaccinee. Even though the necessity of influenza vaccination among HCWs were accepted well in vaccinee compared to nonvaccinee, the accurate reasons for vaccination were not quite understood among HCWs regardless of compliance. Vaccine campaign (30.8%) and advise from doctors (24.7%) were important for the promotion of vaccination among vaccinee. However, major reason for non-compliance among nursing staff and was mis-confidence that their bodies' self defense mechanisms would ward off infection (33.5%) and 'too busy to get injection' for doctors (65%). Conclusion : We conclude that regular education about perceptible benefits and wrong concerns about influenza vaccination among HCW's and easy accessibility to vaccination were important determinants to improve the influenza vaccination. On-site availability of a vaccination-nurse also proved to be important.

석탄회를 이용한 제올라이트의 합성과 중금속 흡착 특성

류완호,이원묵,홍필선,양천희,안재영,백일현,이병노 한국화학공학회 2003 Korean Chemical Engineering Research(HWAHAK KONGHA Vol.41 No.5

석탄회를 이용, 중금속 제거용 흡착제 제조를 목적으로 NaOH를 반응물로 한 수열합성 반응으로 제올라이트를 합성하였으며, 이에 대한 성능특성 및 중금속 흡착실험을 수행하였다. SiO₂와 Al₂O₃를 주성분으로 한 석탄회를 NaOH에 의한 수열합성 반응으로 폐수 중에 포함되어 있는 중금속에 대한 제거능력이 높은 제올라이트를 합성하고자 하였다. 따라서 NaOH 농도, 시간을 변화시키면서 제올라이트를 합성하여 실험한 결과 4 M-NaOH, 4시간에서 최적의 조업조건을 얻을 수 있었다. 산에 의한 전처리 과정을 거친 합성 제올라이트는 pH 7-9.5로 중성을 나타내었다. 또한 산처리 합성 제올라이트를 이용하여 중금속인 P, Pb, Cd, Cr, Mn등의 흡착능을 비교한 결과 P, Pb, Cd 등은 비교적 흡착능이 우수하게 나타났지만 Cr과 Mn 등은 pH가 너무 높기 때문에 거의 흡착이 이루어지지 않았다. Zeolite was synthesized from coal fly ash produced by a domestic power plant and has applications in the removal of heavy metal from waste water. Zeolite was synthesized using a hydrothermal method involving an alkaline reaction with NaOH. The NaOH concentration and reaction times were varied in order to synthesize zeolite showing the maximum removal efficiency of heavy metal from waste water. The synthesis conditions were optimized at the concentration of 4M-NaOH and the reaction time of 4hn. The synthesized zeolite needed washing with HCI solution to improve the removal efficiency of P, Pb. Cd. Cr. Mn and it was maximized at pH 7-9.5 in leaching solution of synthesized zeolite.

만성질환자에서 인풀루엔자 예방 접종의 효능 분석 : 후향적 환자-대조군 연구

박승철,정희진,손장욱,최선주,엄중식,우흥정,천병철,김우주 대한감염학회 2004 감염과 화학요법 Vol.36 No.4

목적: 인플루엔자는 예방접종을 통하여 효과적으로 예방이 가능한 대표적인 호흡기 감염질환이다. 미국이나 국내의 인플루엔자 예방접종 지침에서 고령인구(50세 또는 65세 이상)와 그 외의 만성질환자들을 인플루엔자 예방접종의 일차 대상자로 정하고 있다. 그러나 국내에서는 아직까지 만성질환자들에서의 인플루엔자 백신의 효능평가에 대한 연구결과가 없는 실정이며 국내에서의 만성질환의 분포가 외국의 그것과 일치하지 않기 때문에 본 연구에서는 국내 만성질환자들에서 인플루엔자 예방접종과 연관된 병원입원율의 차이를 비교해 보고자 하였다. 재료 및 방법 : 1999년 11월-2000년 3월(5개월간) 서울 소재 2개 대학병원에 입원한 만성질환자중 발열과 호흡기 증상이 있어 인플루엔자 또는 인플루엔자양 질환이 의심되거나 그로인한 만성질환의 악화로 추정되는 환자군과 이를 배제한 대조군을 중심으로 혈중 인플루엔자 항체가를 조사하였고 인플루엔자 백신접종력을 조사하였다. 결과의 해석은 로지스틱 회귀분석을 이용하였다. 결과 : 만성질환자를 대상으로한 환자 대조군 연구에서 2개 대학병원에서 1년간 조사한 결과 항체 검사에 기준하여 최종적으로 환자군 64명, 대조군 117명이 포함되었다. 환자군에서는 대부분이 호흡기질환(253%)과 심혈관계질환(313%)였던 반면에 대조군은 암(466%)이 가장 많았고 심혈관계질환과 호흡기계질환은 각각 134%, 60%로 낮았다. 또한 두군간에는 예방접종의 경력에서 통계적으로 유의한 차이를 보였으며 이때의 비차비(OR)은 0328로서 인플루엔자 예방접종의 입원 예방효능은 672%이었다. 결론 : 만성질환자, 특히 만성 심폐질환들에서의 인플루엔자 예방접종은 불필요한 입원을 줄이는 효과가 관찰되었다. 따라서 의료인들은 고위험군의 환자들에 대하여 인플루엔자 에방접종을 적극적으로 권장하고 실천하여야 하겠다. Background : Influenza is one of the preventable respiratory disease by annual vaccination. Elderly people and patients with chronic medical disease are the primary target for influenza vaccination according to ACIP (Advisory Committee on Immunization). This study was done to determine whether influenza vaccination affects hospitalization due to influenza like illness or it's related complications among chronic ill patients. Materials and methods : Retrospective, case-control study was conducted for 5 months (Nov. 1999-Mar. 2000). Physicians from two-university hospitals in Korea were instructed to collect clinical data, sera from subjects presenting with a flu-like illness or flu-related exacerbation in patients with chronic underlying diseases. We compared the vaccination history of case patients with control. Logistic regression analysis was used to calculate the odd ratio and efficacy of influenza vaccination. Results : Hospitalization due to ILI (influenza like illness) or it's related complications were observed more frequently in patients with chronic lung disease (25.3%) and chronic cardiac disease (31.3%) compared to others. Influenza vaccination resulted in fewer hospitalization with ILI or ILI-related acute exacerbation of underlying disease in chronic ill patients (adjusted odd ratio, 0.328 [CI, 0.14 to 0.73]) during influenza seasons. Conclusion : For patients with chronic disease, influenza vaccination is associated with substantial health benefit including fewer hospitalization. Health care providers should take advantage of all opportunities to immunize these high-risk patients.

급속응고된 N-type Bi₂Te_(2.75)Se_(0.15) 열전재료의 미세조직과 열전특성에 미치는 압출비의 영향

김태경,이상일,임종호,손현택,김택수,천병선 대한금속재료학회 2005 대한금속·재료학회지 Vol.43 No.1

The n-Type thermoelectric compounds of Bi₂Te_(2.75)Se_(0.15) doped with 0.1 wt% SbI₃ were fabricated by gas atomization process and extruded under ratio of 16:1 and 28:1 at 450℃. The effect of extrusion ratio on the microstructures and thermoelectric properties were investigated by a combination of microscopy, XRD and thermoelectric properties. Grains of extruded bars are smaller than those of heated powder at extrusion temperature (450℃) due to the dynamic recrystallization but with increasing the amount of plastic deformation, grains of specimen extruded with 28:1 were slightly coarse. The compressive strength of hot extruded bar under 28:1 is 160 MPa and with decreasing the extrusion ratio to 16:1, the value is 250 MPa. The Seebeck coefficient a and electrical resistivity p were decreased with increasing ratio, while thermal conductivity x was increased. this results from decrease of carrier scattering and increase of carrier mobility. Extruded bar under ratio of 16:1 shows the higher value of figure of merit (Z=2.50x10^(-3)/K) than that of 28:1 (Z=2.07x10^(-3)/K). (Received June 24, 2004)