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고상법에 의한 100 nm BaTiO<sub>3</sub> 분말의 합성
김정환,정한승,조준엽,홍정오,김영태,허강헌,Kim, Jung-Hwan,Jung, Han-Seong,Cho, Joon-Yeob,Hong, Jeong-Oh,Kim, Young-Tae,Hur, Kang-Heon 한국세라믹학회 2009 한국세라믹학회지 Vol.46 No.2
$BaTiO_3$ powder was synthesized by the solid-state reaction of fine $BaTiO_3$ and $TiO_2$ raw materials. Fine grinding media of 50 and 300 microns were used for obtaining fine particulate mixture of $BaTiO_3$ and $TiO_2$ with high homogeneity. Effect of the size of grinding media on the synthesis mechanism of $BaTiO_3$ was discussed on the basis of the particulate morphology and thermogravimetry data for the mixture powders. By using the finer grinding media, $BaTiO_3$ was formed at the lower temperature and the particle size with the relatively narrower distribution could be obtained. $BaTiO_3$ powder with the average size of 100 nm was synthesized by the solid reaction in vacuum atmosphere.
R&D와 규모의 영세성이 산업별 총요소생산성에 미치는 영향
김정환,이동기,이부형,주원,Kim, Jung-Hwan,Lee, Dong-Ki,Lee, Bu-Hyung,Joo, Won 한국벤처창업학회 2007 벤처창업연구 Vol.2 No.4
There were many comprehensive analyses conducted within the existing research activities wherein factors affecting technology progress including investment in R&D vis-${\Box}$-vis their influences act as the determinants of TFP. Note, however, that there were few comprehensive analysis in the industrial research performed regarding the impact of the economy of scale as it affects TFP; most of these research studies dealt with the analysis of the non -parametric Malmquist productivity index or used the stochastic frontier production function models. No comprehensive analysis on the impacts of individual independent variables affecting TFP was performed. Therefore, this study obtained the TFP increase rate of each industry by analyzing the factors of the existing growth accounting equation and comprehensively analyzed the TFP determinants by constructing a comprehensive analysis model considering the investment in R&D and economy of scale (smallness by industry) as the influencers of TFP by industry. First, for the TFP increase rate of the 15 industries as a whole, the annual average increase rate for 1993${\sim}$ 1997 was approximately 3.8% only; during 1999${\sim}$ 2000 following the foreign exchange crisis, however, the annual increase rate rose to approximately 7.8%. By industry, the annual average increase rate of TFP between 1993 and 2000 stood at 11.6%, the highest in the electrical and electronic equipment manufacturing business and IT manufacturing sector. In contrast, a -0.4% increase rate was recorded in the furniture and other product manufacturing sectors. In the case of the service industry, the TFP increase rate was 7.3% in the transportation, warehousing, and communication sectors. This is much higher than the 2.9% posted in the electricity, water, and gas sectors and -3.7% recorded in the wholesale, food, and hotel businesses. The results of the comprehensive analysis conducted on the determinants of TFP showed that the correlations between R&D and TFP in general were positive (+) correlations whose significance has yet to be validated; in the model where the self-employed and unpaid family workers were used as proxy variables indicating the smallness of industry out of the total number of workers, however, significant negative (-) correlations were noted. On the other hand, the estimation factors of variables surrogating the smallness of scale in each industry showed that a consistently high "smallness of scale" in an industry means a decrease in the increase rate of TFP in the same industry.
산 완충능력과 토양 성분이 동전기-펜톤 공정에 의한 phenanthrene 오염토양 정화에 미치는 영향
김정환,나소정,박주양,변영덕,Kim, Jung Hwan,Na, So Jeong,Park, Joo Yang,Byun, Young Deog 한국지하수토양환경학회 2013 지하수토양환경 Vol.18 No.1
This research was conducted to investigate effects of acid buffering capacity and soil component in treatment of phenanthrene using electrokinetic-Fenton process. In Hadong clay of high acid buffering and low iron oxide content, it was difficult to oxidize phenanthrene due to shortage of iron catalyst and scavenger effect of carbonate minerals. The desorbed phenanthrene conductive to Fenton oxidation was transported toward cathode by electroosmotic flow. However, in Youngdong illitic clay, oxidation of phenanthrene near anode readily occurred compared to Hadong clay due to high iron content and low acid buffering capacity.
새로운 BF<sub>2</sub>-Chelate 화합물들의 합성
김정환,김영은,Kim, Jung-Hwan,Kim, Yeung-Eun 대한화학회 2004 대한화학회지 Vol.48 No.4
$BF_2$-chelate 형태의 4-pyrimidylideneacetonitrile 유도체들은 4-pyrimidylideneacetonitrile 유도체들의 H-chelate 화합물들과 boron trifluoride diethyl etherate를 반응시켜 얻을 수 있었다. 또 이들 H-chelate 화합물들은 2-cyanomethylpyridine 유도체들에 여러가지 친전자체들 즉 4,6-dichloropyrimidine, 4,6-dichloro-2-methylpyrimidine, 4,6-dichloro-2-heptadecylpyrimidine, 4,6-dichloro-2-phenylpyrimidine, 4,6-dichloro-5-phenylpyrimidine 그리고 4,6-dichloro-2,5-diphenylpyrimidine을 친전자성 치환반응시켜 만들었다. 화합물에 대한 구조는 분광학적인 방법으로 분석하였다. 4-pyrimidylideneacetonitrile derivatives containing $BF_2$-chelate have been synthesized from H-chelates of 4-pyrimidylideneacetonitrile derivatives and boron trifluoride diethyl etherate. These H-chelates were prepared by the electrophilic substitution of 2-cyanomethylpyridine derivatives with electrophiles such as 4,6-dichloropyrimidine, 4,6-dichloro-2-methylpyrimidine, 4,6-dichloro-2-heptadecylpyrimidine, 4,6-dichloro-2-phenylpyrimidine, 4,6-dichloro-5-phenylpyrimidine and 4,6-dichloro-2,5-diphenylpyrimidine. Structures of the target molecules were identified by spectra methods.
초등학교 수학과 ICT 활용 교육에서 스프레드시트를 활용한 교수-학습에 관한 연구
김정환,구정모,한병래,Kim, Jung-Hwan,Gu, Jung-Mo,Han, Byoung-Rae 한국정보교육학회 2009 정보교육학회논문지 Vol.13 No.3
Many current researches are limited in the statistics field, which is a part of mathematics class in the secondary school. Moreover, it's hard to apply to the elementary school since they are written in English. To overcome this limitations, the objectives from the unit that is suitable for using EXCEL in the elementary mathematics lessons are selected in this research. And a problem-based learning model for these lessons would be introduced that it can help students to focus on solving substances of the problems by reducing the time for arithmetic calculation.
폴리프로필렌 글리콜의 표면-보조 레이저 탈착/이온화에서 선형 비행시간 질량분석기의 분해능 개선을 위한 시간 지연 추출법의 응용
김정환,강위경,Kim, Jung Hwan,Kang, Wee Kyung 대한화학회 2000 대한화학회지 Vol.44 No.4
폴리프로필렌 글리콜의 표면-보조 레이저 탈착/이온화를 이용하여 선형 비행시간 질량 분석기에서 시간-지연 추출법이 분해능 개선, 질량-초점 길이 및 기기 퍼짐 효과의 영향을 수치계산과 비교하여 평가해였다. 비행시간 초점영역은 고저압 펄스의 지연 시간에 비례하였고 지연 시간 변화로 질량 초점 영역을 쉽게 조절할 수있었다. 시간 지연 추출법으로 얻어진 질량 스펙트럼의 분해능은 4500으로 연속추출법(20kV)에 비해 7배 정도 개선되었고 △m=2000의 질량-초점길이를 보여주었다. 시간 지연 추출법에서 기기 퍼짐 요인에 의한 분해능 개선의 한계를 계산하였고 5ns의기기 퍼짐 효과에 의해 동위원소 분리 검출은 분자량 2500까지 가능하였다. 시간 지연 추출법을 이용하여 폴리프로필렌 글리콜 분자가 탄고 표면에서 탈착될 때 생성되는 분열체 시리즈를 개선된 고분해능으로 동위원소 분포 수준으로 확인하였으며 분열 경로 규명 및 동위원소 비 질량분석기로의 응용 가능성을 시험하였다. The pulsed-delayed extraction (PDE) in linear time-of-flight mass spectrometer(TOF MS) is characterized on the enhancement of resolution, mass-depth of focus and effect of instrumentahan 2000. The ion signals separate isotopically by up to molecular weight of 2500 in instrumental broadening of 5 ns, which is a good agreement with calculation. The fragmentation paths of PPG can be sug-gested by the isotopica distributions of fragment series produced when PPG desorbed from graphite surface.