YAG LASER에 의한 공구강의 표면개질에 관한 연구

옥철호,강형식,박흥식,전태옥 韓國工作機械學會 2000 한국생산제조학회지 Vol.9 No.2

Laser induced surface hardening of Tool steel(STC5) can be achieved either with or without surface melting. In trans-formation hardening, as the surface is heated to a temperature below its melting point and is rapidly cooled, solidified microstructures are usually much finer and stronger than those of the base matals. For this reason, surface modification of tool steel by YAG laser irradiation has been studied as a fuction of processing parameters such as, power density, pulse width, defocusing distance, and molten depth. The high energy density changes and refines the microstructure of the near surface layer. In the case of beam passes, martensite formed in the melt zone exhibited very high vickers hardness values. Molten depth and width depend on defocusing distance, and energy of black color painting is more absorptive than other color painting.

레이저 경화면의 형상특징 해석을 위한 프랙탈 차원의 적용

옥철호,조연상,배춘익,박흥식,전태옥 동아대학교 생산기술연구소 2000 生産技術硏究所硏究論文集 Vol.5 No.2

The determination of surface topography is believed to be extremely important in the areas of contact mechanics, adhesion and friction. In order to describe topography of various frictional surface, the harding test was carried out under different experimental conditions in dry friction. And fractal descriptors was applied to frictional surface of laser modified steel with image processing system. These descriptors to analyze surface structure are fractal dimension. Surface fractal dimension can be determined by sum of intensity difference of surface pixel. Topography of frictional surface can be effectively obtained by fractal dimensions.

분편 인플루엔자백신(split influenza vaccine)의 임상효과 및 면역원성에 관한 연구

우흥정,김동림,정희진,천병철,이주연,안정배,김지희,박찬,신영규,김우주,김민자,박승철 대한화학요법학회 1999 대한화학요법학회지 Vol.17 No.1

목적 : 아단위 인플루엔자 백신 접종 후 백신의 인플루엔자 예방효과, 인플루엔자 방어 항체형성, 인플루엔자 백신의 안전성을 조사하고자 하였다. 방법 : 총 571명을 대상으로 인플루엔자 백신 접종을 하였고, 이들 접종자에서 인플루엔자 양질환의 이환을 조사하여 인플루엔자 백신의 인플루엔자예방효과를 알아보았고, 백신의 접종 전 및 접종 4주 후 혈청에서 혈구응집억제물(Hemagglutination Inhibition : HAI) 항체 검사를 실시하여 백신의 방어항체생성을 조사하였고, 백신의 안전성을 알아보기 위해 백신접종 후 1주일 이내의 부작용을 조사하였다. 결과 :백신 접종군과 백신 비접종군에서 인플루엔자 양 질환의 이환을 조사한 결과 접종군 28.35%, 비접종군 35.88%으로 나왔으며, p 값이 0.001로 통계적으로 접종군에서 유의하게 낮았고, 인플루엔자 양 질환의 예방 효과는 20.97%를 보였다. 백신의 방어항체 형성의 평가를 위해 유럽의 인플루엔자 백신 허가 기준을 조사하였는데 B/Guangdong/5/94균주의 백신접종 후 항체가 40이상의 비율을 제외한 다른 기준은 모두 만족 시켰다. 부작용은 전체 조사자 521명중 149명(29%)으로 주로 접종 부위의 국소 부작용을 호소했고, 전신 부작용은 2% 내외였으며 특별히 심각한 부작용은 발견되지 않았다. 결론 : 분편 인플루엔자 백신은 인플루엔자양질환의 예방과 방어항체생성에 효과 있으며 안전한 것으로 사료된다. Background : The safety and effectiveness of influenza vaccine are well known in developed country. The influenza vaccination has been recommended as one of the tentative immunization schedule for indicated persons since 1997 in Korea. But there are still no available data about them, even though nearly 5 million doses of influenza vaccine were used in 1997-1998 season. So it is immediately needed to investigate the safety. efficacy and immunogenicity of influenza vaccine among Korean. Methods : We studied the clinical efficacy of influenza vaccine by monitoring Occurrence of influenza-like illness in influenza risk group(vaccination ; 300, non-vaccination; 215) from December in 1997 to March in 1998. We used the split quadrivalent influenza vaccine containing 15 microgram of hemagglutinin of A/Beijing/262/95(HlNl), A/Wuhan/359/95(H3N2), B/Mie/1/93 and B/Guangdong/5/94. Hemagglutination inhibition(HA1) antibody titers were determined before immunization and 1 months after vaccination And we evaluated adverse effect of influenza vaccination at 7 days after vaccination. Results : Influenza vaccination was associated with si@icant reductions in influenza-like spptoms(vaccination group; 28.35%, non-vaccination group, 35.88%, p=0.001). The preventive effect of influenza-like i3lne.s among influenza risk goup was 20.97%. And immunogenicity of influenza A and B exceeded all of the European licensure criteria for immunogenicity except postvaccination proportion of titers 240 of B/Guangdong/5/94 strain. And the adverse effects were mainly local injection site problem and no serious adverse effect was noted. Conclusion : Split influenza vaccine is safe, inmunogenic and eff'tive in influenza risk group in Korea.

초산아연을 원료로 하는 ZnO CVD

정상철,박흥철 全南大學校 觸媒硏究所 1996 觸媒硏究 論文集 Vol.18 No.-

ZnO thin films were prepared from zinc acetate using a horizontal tube hot-wall CVD reactor under various pressure and the dependency of film characteristics on operating conditions was studied. The profile of the thin film grown on microscale trenches and the macroscopic growth rate distribution along the results indicate that the CVD reaction mechanism changes with operating pressure. A model was proposed to explain the experimental results. The model reveals that, at higher pressures, ZnO film is formed directly from zinc acetate through the slow surface reaction, as was pointed out in our previous paper APCVD. At low pressure, active species formed in the gas phase via gas-phase reaction. At intermediate pressure, these two reaction paths coexist but the active intermediates are deactivated through molecular collisions with nitrogen. The experimental results are explained by assuming the rate of the reverse reaction is proportional to CN₂³

SM45C의 Laser 표면개질 조건에 따른 마멸특성에 관한 연구

옥철호,임동욱,서영백,박흥식,전태옥 동아대학교 생산기술연구소 2000 生産技術硏究所硏究論文集 Vol.5 No.1

Surface modification of plain carbon steel (SM45C) by Laser are usually much finer and stronger than the base metals. Nd-YAG laser source changes and refines the microstructure of the near surface layer, leading to enhanced hardness and wear resistance. The present study was undertaken to investigate the wear behavior and a processing parameters such as, power density, pulse width, defocusing distance, and molten depth for surface modification. The wear test was carried out under different experimental condition using the wear test device and the annular surfaces of wear test specimens as well as mating specimen of alumina ceramics(Al_2O_3) was rubbed in dry sliding condition. The results show that molten depth and width depend on defocusing distance. The wear loss was much in lower speed range below 0.2m/sec and in higher speed range above 0.7m/sec, but It was little in intermediate speed range. It depends on oxidation and wear speed.

수직형 CVD 반응기에서 ZnO 박막의 합성

정상철,박흥철,김필성 全南大學校 觸媒硏究所 1996 觸媒硏究 論文集 Vol.18 No.-

ZnO was synthesized by deposing gas phase zinc acetate on a rotating disk in a vertical thermal CVD reactor. Structural and optical characteristics of the ZnO thin film were investigated after deposition. Dependency of the film growth rate on the temperature of deposition was so high in the ranges of 350∼400℃ that the energy of activation was 150.54 kJ/mol, while it reduced to 27.72 kJ/mol, above 400℃. Deviation of growth rate was large at low spin rate in case of disk rotation but showed that it was small at high spin rate. The flux of carrier gas a factor of the growth rate. As a result investigation on effect for wafer type, it was known that the deviation of the growth rate could be expressed as a function of wafer type. ZnO thin film deposited on glass had a low absorbance at 400~900nm wave length ranges and oriented along the C-axis strongly.

리네졸리드로 치료한 반코마이신 내성 Enterococcus faecium 뇌수막염 : 증례보고 및 문헌고찰

이창섭,박성주,이용철,이양근,이흥범 대한감염학회 2010 감염과 화학요법 Vol.42 No.3

Vancomycin-resistant enterococci (VRE) infection is a serious problem because optimal therapy has not been established. Different agents in various combinations, including teicoplanin, chloramphenicol, and quinupristin/dalfopristin, have been used to treat patients with VRE meningitis, but the efficacy of these agents is not satisfactory because of their limited ability to penetrate into the cerebrospinal fluid. We report a case of nosocomial vancomycin-resistant Enterococcus faecium meningitis in a patient with ventriculoperitoneal shunt that was successfully treated with linezolid. We will also review previously reported cases of vancomycinresistant E. faecium meningitis treated by linezolid.

평면연삭버어의 가공조건에 의한 영향

이광영,옥철호,서영백,박흥식,전태옥 동아대학교 공과대학부설 생산기술연구소 1998 生産技術硏究所硏究論文集 Vol.3 No.2

This study has been carried out to prevent and decrease the grinding burr under various working conditions; number of grinding passes, depth of cut, hardness of the materials and work speed. Grinding wheel is WA grinding wheel and workpieces are SM45C, SS41, SCM23 and STS 304. The results of tained from this study are as follows; The length of gringing burr increased with increasing grinding passes and it has nothing to do with materials and heat treatment. The size of grinding burr increased with increasing grinding depth and feed speed. The size of grinding burr decreased with increased cross setion and of workpiece. According as the hardness of material was increased, the width of grinding burr decreased conspicuously owing to suppression of plastic zone of burr root part.

계절창고 속에 포장 저장된 과일의 호흡 예측 모델

김광섭,심승우,나현정,조인철,정흥조,박찬영 전남대학교 촉매연구소 2001 觸媒硏究 論文集 Vol.22 No.-

Fruit are normally kept in a pouch of cold storage room in winter. In this work, a mathematical model that is emulating the fruit respiration in the pouch of the storage has been established. The calculated result is compared to the actual measured gaseous composition change of pear in the packaging pouch LDPE film incorporated with silver coated ceramic powder. The presented model, that is combining polysaccharide digestion kinetics in pear, Fickian diffusion for permeation of the film and sigmoidal adsorption equilibrium between the film and gases, predicts the respiration of the pear in the packing film fairly well.

Fractal 차원에 의한 표면경화면과 마찰면의 형태해석

문병주,조연상,옥철호,박흥식,전태옥 동아대학교 생산기술연구소 2001 生産技術硏究所硏究論文集 Vol.6 No.1

The determination of surface middleography is believed to be extremely important in the areas of contact mechanics, adhesion and friction. In order to describe middleography of various rubbed and hardened surface, the wear test was carried out under different experimental conditions in dry friction. And fractal descriptors was applied to rubbed and hardened surface of laser modified steel with image processing system. These descriptors to analyze surface structure are fractal dimension. Surface fractal dimension can be determined by sum of intensity difference of surface pixel. middleography of rubbed and hardened surface can be effectively obtained by fractal dimensions.