[논문]Operational Characteristics of CO2 Laser Adopted by Superposing-Discharge

Hee-Je Kim,Hyun-Ju Chung,Byoung-Dae Min,Jong-Han Joung,Sung- lun Park 釜山大學校生産技術硏究所 2003 生産技術硏究所論文集 Vol.62 No.-

오늘날 현저한 CO2 레이저의 응용 추세에 발맞추어 보다 다양한 형태의 출력 제어 기술이 대두되고 있다. 본연구에서는multi-Pulse Superposing-Discharge 기술을 이용하여 다양한형태의 CO2 레이저의 펄스를 성형 하였다. 펄스 성형을 위한 방법으로 PIC one-chip microprocessor를 이용하여 삼중 PFN 모률의 SCR을 각각 고유의 지연시간을 가지도록 제어하였다. 실험에 사용된 삼중 PFN 모률의 전원 회로는 각각 캐패시터 인덕터,SCR,고압 펄스 트랜스 그리고 고압 트랜스 2차측에 브릿지 정류기로 구성 하였다. 고압 펼스 트랜스의 1차측을 제어하므로서 PFN 모률의 동작을 저 전압에서 수행 할 수 있다. 트랜스의 2차측에 연결된 전파 정류기는 펄스 에너지를 부하에 지속적으로 전달한다. 본 연구에서는 삼중 PFN 모률의 각각의 SCR을 다른 시간 가격을 두고 트리거 하므로서 다양한 Long pulse shaping을 실현하였다. 또한 약 250-1000μs 의 주기를 가지는 다양한 펄스형 레이저 빔을 얻었다.

N-벤조일-이미다졸 유도체의 가수분해반응

성대동,엄태섭,이종팔,박유미,박현석 東亞大學校 1992 東亞論叢 Vol.29 No.1

The pseudo first order rates for hydrolyses of N-benzoyl-(2,4,5-triphenyl)-imidazole and N-benzoyl-(4,5-diphenyl)-imidazole have been measured by means of spectrometry in over all pH range at 30˚C with the ionic strength of 0.5M KC1. In the case of N-benzoyl-(2,4,5-triphenyl)-imidazole, the general acid catalytic reaction was not observed, while the general base catalytic reaction showed in near the range of pH=7. In the case of N-benzoyl-(4,5-diphenyl)-imidazole, the general acid and base catalytic reaction showed at the regions of less than pH=4 and more than pH=10. The rate constants for pH independent reaction of N-benzoyl-(2,4,5,-triphenyl)-imidazole were shown a little bit faster than those of the corresponding to N-benzoyl-(4,5-diphenyl)-imidazole. The reaction mechanism of pH independent reaction was interpreted by means of thermodynamic parameters, and the isotope effect. The magni-tude of ΔH??, ΔS??, ??/?? values indicated that the bond breaking had been progressed more than bond formation in the transition state.

삼배위 황화합물의 산촉매 가수분해 반응

성대동,이종팔,엄태섭 東亞大學校 大學院 1995 大學院論文集 Vol.20 No.-

The acid catalyzed hydrolysis of N-substituted sulfinamides have been studied in agueous solution of perchloric acid at 25℃ by spectrophotometrically. The pH-rate profile for N-phenylbenzene-sulfinamide(a); N-p-chlorophenybenzenesulfinamide(d), N-phenyl-p-chlorobe enesulfinamide(f) and N-phenyl-o-chlorobenzenesulfinamide (h) shows linearity, while those for N-p-methoxyphenylbenzenesulfin-amide(b), N-p-methylphenylbenzenesulfinamide(c) and N-phenyl-p-ethylbenzenesulfinamide(e) have a break at about pH 3. The break of pH-rate profile is ascribed to a change in the rate-determining step of the reaction involving a hypervalent intermediate.

Dabsyl Chlorides의 親核性 置換反應

成大東,朴現錫,柳俊夏,金良姬,李鍾八,嚴泰燮 東亞大學校 1990 東亞論叢 Vol.27 No.1

Kinetic studies of nuclsophilic substitution reaction of dabsyl chloride with pyridines have been investigated at 30℃ in a range of methanol-acetonitrile bianary solvent mixtures. The order of magnitude fo reactivity is β-picoline > pyridine > 1.5-N D A > α-picoline to react with dabsyl chloride, especially in case of α-picoline, the reactivity revealed lower than others, it is suggestd that nitrogen atom of pyfidine ring has a steric hinderance by the neightboring methyl group. The value of ρ(-0.96∼4.59) and β(0.36∼0.67) associated with a change of substituent in the nucleophile are large and indicate a realtively advanced bond formation in the transition state. Solvatochraomic correlations were predicted the importance of bond formation transition state, showing a greater contribution of polaritypolarizability (π*) lone paired to hydro-gen bond donar acidity (α). We conclude that the reaction of dabsyl chloride with pyridine proceed via S2 type reaction mechanism, as well as the reaction of dansyl chloride pyridine.

염화나프토일의 親核性置換反應에 미치는 溶媒效果

成大東 東亞大學校 1980 東亞論叢 Vol.17 No.2

1-염화나프토일과 2-염화나프토일의 가매분해반응을 에탄올-아세토니트릴, 2-프로판올-아세토니트릴, 에탄올-아세톤, 2-프로판올-아세톤, 에탄올-물, 2-프로판올-물, 3차 부탄올-물 혼합용매 속에서 전기전도도법으로 측정하였다. 혼합용매의 조성에 관계없이 1-염화나프토일이 2-염화나프토일보다 속도가 크게 나타났다. 이것은 Dewar지수 Nr과 Streiwiesr의 σ+값과도 일치하였다. 1-염화나프토일은 Sn2전이상태에서 반응중심탄소가 sp²에서 sp³로 변하므로 peri-hydrogen effect가 relieve 됨을 알 수 있었으며 또한 모든 반응이 대체로 Sn2 반응메카니즘으로 진행됨을 알 수 있었다. 동일한 반응기질이 에탄올과 2-프로판올 및 공용매인 아세토니트릴의 혼합용매속에서도 메탄올-아세토니트릴 혼합용매에서와 같은 최대속도 현상이 나타났다. 즉 메탄올-아세토니트릴 혼합용매게에서는 메탄올의 물분율 0.85에서 최대치가 나타나는데 비해 등유전성이 아닌 에탄올-아세토니트릴 혼합용매게에서는 에탄올의 물분율 0.78에서 2-프로판올-아세토니트릴 혼합용매계에서는 2-프로판올도의 물분율 0.62에서 각각 최대속도상수를 갖는다. 이것으로 미루어 볼 때 에탄올과 2-프로판올도 메탄올과 같이 수소결합을 형성하여 다량체를 만들고, 가용매분해반응에서 아세토니트릴이 첨가될 때 이들 알코올의 다량체 구조가 파괴됨을 알 수 있었다. 또한 섭동분자이론(PMO)에서 구한 비결합분자궤도함수(NBMO)의 계수와 반응속도의 대수가 거의 직선적으로 비례함을 알 수 있었다. The kinetics for solvolysis of 1-naphthoyl and 2-naphthoyl chlorides have been measured in solvent mixtures, EtOH-Me추, 2-PrOH-MeCN, EtOH-(Me)₂CO, 2-PrOH-Me)₂CO, EtOH-H₂O, 2-PrOH-H₂O and t-BuOH-H₂O. The rate constants of 1-naphthoyl chloride were faster than 2-naphthoyl chloride in all solvent mixtures. This agrees with Dewar number, Nr and Streitwieser's σ+ value. It was concluded that the valence state of carbonyl carbon changed from sp² to sp³ in transition state and peri-hydrogen effect was relieved; the solvolytic reactions proceeded by Sn2 mechanism in all solvent mixtures system. There were maxima in rate of reaction for EtOH-MeCN, 2-PrOH-MeCN mixtures in the same way as for MeOH-MeCN mixture. The maximum rate in EtOH-MeCN mixture was observed at mole fraction of EtOH, 0.85 and in 2-PrOH-MeCN mixture was observed at mole fraction of 2-PrOH, 0.62. This behavior is interpreted as the structure of alcohols also has hydrogen bonding structure, and the polymer structure of alcohols is destroyed by adding aprotic solvent, MeCN. Comparing the perturbation molecular orbital theory in the transition state, the logarithms of solvolytic rate constants have been found to be proportional to the AO coefficient of nonbonding molecular orbital, 2a? in this solvolytic reaction.

Drosophila busckii의 韓國集團에서 있어서 同位酵素 多形現象

成耆昌,尙椿植,金彧,金大鎰 성균관대학교 기초과학연구소 1985 論文集 Vol.36 No.1

Genetic structure and variability were investigated in four Korean populations of Drosophila busckii. Eight allozyme loci were analysed by means of starch gel electrophoresis. The proportions of polymorphic loci and loci heterozygous per individual were estimated to be 0.25 and 0.051, respectively. The average genetic similarity between four populations was found to be S―=0.977. This value is similar to the other Drosophila populations reported. However, the gene variation of D. busckii in this study appeared to be the least variable among 28 Drosophila species reported. It is suggested that the low gene variation in D. busckii might be due to adaptation of this species to a narrow niche, but the possibility of occurrence of the random drift cannot be excluded.

대장 및 직장암 환자에서 DNA Ploidy 및 증식능과 기존의 예후인자와의 상관관계 분석

김상철,김대성,노병선,윤광수 대한대장항문학회 1996 Annals of Coloproctolgy Vol.12 No.1

Drosophila quinaria Species Group의 遺傳的 近緣關係

成耆昌,金正洙,金大鎰,金彧,金溶聲 성균관대학교 기초과학연구소 1985 論文集 Vol.36 No.2

The genetic relatedness among the Korean Drosophila quinaria species group, including D. nigromaculata, D. unispina, D. brachynephrose, and D. angularis, has been examined by using horizontal starch gel electrophoresis. The results showed that none of the ten isozyme patterns examined for these four species was identical. The average genetic similarity among the four species was found to be 0.440. The similarity among three species. D. unispina, D. brachynephrose, and D. angularis was 0.466. The relatedness was found to be closest between D. nigromaculata and D. unispina, showing 0.640. D. nigromaculata and D. angularis showed relatedness of 0.258. The results suggested that these four species appear to be genetically related at the level of sibling species. The percent polymorphism in D. brachynephrose was found to be 76.9%, showing significant genetic variations.

수처리 부산물로 생성되는 염소산화물의 효율적 제거에 관한 연구

성대동,이성식 동아대학교 환경문제연구소 1999 硏究報告 Vol.22 No.1

The photodegradation efficiency of chlorine oxides in the drinking water has been studied by means of laser flash photolysis. The results are summarized as follows ; A high amount of ClO is produced just at the irradiation of laser flash. The absorption spectrum of ClO shows strong on the spectrophotometric measurement. The efficiency of removal of ClxOy reveals about 60~70% within 2㎲ after laser flash irradiation. The removal efficiency is decreased with the increase of the water thickness from 40㎝ to 80㎝ and also the efficiency is decreased about 4~6%. The removal rate of Cl₂O_(7) shows 3 times higher than one of Cl₂O_(6).

재량적 회계변경의 정보효과

최성규, 서대석 영남대학교 사회과학연구소 2000 社會科學硏究 Vol.20 No.1

본 연구는 재량적 회계변경에 대한 자본시장의 반응을 검증하기 위한 5개의 가설을 제시하고 이를 실증하였다. 이 가설들의 기본 논리는 대부분의 재량적 회계변경이 회계정보의 유용성을 증가시키기보다는 기업의 재무상태와 경영성과를 유리하게 보이기 위한 경영자의 기회주의적 유인이 더 많이 작용했을 것이라는 데 초점을 맞추고 있다. 가설을 검증하기 위하여 재량적발생에 대한 반응계수를 살펴보았으며, 검증결과, 가설과 일관된 결과를 얻을 수 있었다.