• Journal of the Korean Chemical Society
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• v.60 no.4
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• pp.251-256
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• 2016

This paper describes the synthesis of alkali metal salts of urea (ureates) and their application to the direct preparation of 4-nitrosoaniline from nitrobenzene via nucleophilic aromatic substitution of hydrogen. Sodium and potassium ureates were readily prepared from the reaction of urea with sodium hydride, metal methoxides, and metal hydroxides. The effect of ureates as nucleophiles on the conversion of nitrobenzene to 4-nitrosoaniline was investigated and compared with that of a urea-metal hydroxide mixture. It was found that the ureates were superior for producing 4-nitrosoaniline owing to their higher thermal stability of the ureate. The ureate obtained from the treatment of urea with sodium hydride gave the highest yield for the preparation of 4-nitrosoaniline. The ureates generated from the reaction of urea with metal hydroxide also gave high yields of 4-nitrosoaniline. Catalytic hydrogenation of 4-nitrosoaniline afforded polymer-grade 1,4-benzenediamine in quantitative yield.

• YAKHAK HOEJI
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• v.43 no.5
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• pp.566-571
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• 1999

(1H-1,2,4-Triazolyl) methy-4-(sub). phenyl-5-methyl-1,3-dioxolan-2-yliden (3) derivatives were synthesized and tested for their antifungal activities. The designed compounds with a 1,2,4-triazolylmethyl group at the 4-position of 1,3-dioxolan-2-yliden moiety were synthesized by reaction of difluorinated olefins(2) with (2R, 3R)-2-(2,4-dihalophenyl)-1-(1H-1,2,4-triazol-l-yl) butane-2,3-diol (1). These compounds were tested for in vitro antifungal activities against 16 fungi species. The MIC values were determined by the micro broth dilution method. In general, 1,3-dioxolan-2-yliden derivatives showed antifungal activities in vitro. Among them, (4R, 5R)-4-(2,4-difluorophenyl)-5-methyl-2-[1-(3,4-methylenedioxypheny)meth-ylidene)-1,3-dioxolon-4-yl(1H-1,2,4-triazollyl)methane showed superior antifungal activities to fluconazol and ketoconazol.

• Proceedings of the Korean Society for Bio-Environment Control Conference
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• 2001.04b
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• pp.51-56
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• 2001

This study was carried out to research the effect of nutrient composition and GA4＋7 on growth, flower quality and bulb development in special hydroponics of cut tulip. Flowering of 'Cassini' was markedly accelerated by standard+GA4＋7, K200＋GA4＋7, N250＋GA4＋7 treatment, last internode was increased by N250 as compared with other treatment. For 'Christmas Marvel', flowering was promoted by K250＋GA4＋7, last infernode and total length were also increased with K250＋GA4＋7 as compared to other treatment. For 'Golden Apeldoorn', flowering was accelerated by K200＋GA4＋7, last internode was increased with N300＋GA4＋7 treatment and total length was increased in N250＋GA4＋7 treatment as compared with the standard plants. Bulb weight and number of 'Cassini', 'Christmas Marvel'and 'Golden Apeldoorn' were decreased by GA4＋7 as compared to non-treatment, and bulb diameter was not affected by GA4＋7.

• Proceedings of the Korean Vacuum Society Conference
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• 2000.02a
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• pp.151-151
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• 2000

We have studied the atomic structure of Si(100)-c(4$\times$4) reconstruction using scanning tunneling microscopy(STM). The c(4$\times$4) reconstruction can be formed by annealing the hydrogen exposured surface at temperatures between 850 and 960 K. At this temperature ranges, adsorbed hydrogen atoms are all desorbed. Therefore, the c(4$\times$4) reconstruction is due to the Si dimers on surface. The filled and empty state images of the STM were interpreted in terms of Si dimers in c(4$\times$4) primitive cell forming the reconstruction. Based on the STM images and hydrogen adsorption experiment on c(4$\times$40 surface, we suggest that Si dimers in c(4$\times$40 unit cell are perpendicular ad-dimer to the underlying Si dimer rows.

• Tribology and Lubricants
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• v.4 no.2
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• pp.44-51
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• 1988

Titanium carbide(TiC), Titanium nitride(TiN), and Titanium carbonnitride(Ti(C,N)) films were deposited on $Si_3N_4$-TiC composite cutting tools by chemical vapor deposition(CVD) using $TiCl_4-CH_4-H_2$, $TiCl_4-N_2-H_2$, and $TiCl_4-CH_4-N_2-H_2$ gas mixtures, respectively. The experimental results indicate that TiC coatings compared with TiN coatings on $Si_3N_4$ -TiC ceramic have an improved microstructural property, good thermal shock resistance, and good interfacial bonding. However TiN coatings compared with TiC coatings have a low friction coefficient with steel and good chemical stability. It is found by cutting test that coated insert compared with $Si_3N_4$-TiC ceramic have a superior flank and crater wear resistance. And multilayer coating compared with monolayer coating shows a improved wear resistance.

• Proceedings of the Korean Information Science Society Conference
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• 2012.06c
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• pp.344-346
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• 2012

스마트폰에서의 3D 게임/애플리케이션에 대한 사용자의 요구는 나날이 증가하고 있다. 3D 게임/애플리케이션은 내부적으로 $4{\times}4$ 행렬을 가지고 여러 가지 좌표 변환을 수행하기 때문에, 보다 빠른 3D 그래픽스 처리를 위해서는 $4{\times}4$ 행렬 연산의 최적화가 필수적이다. $4{\times}4$ 행렬 연산중에 역행렬 연산에 대해 살펴보고, ARM 프로세서에서 지원하는 Neon 연산자를 이용해서 $4{\times}4$ 행렬의 역행렬 연산을 개선할 수 있다.

• Journal of Drive and Control
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• v.13 no.1
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• pp.10-17
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• 2016

e-4WD(Electric-4WD) system is a 4WD(4-Wheel Drive) System that can transform a car into a Hybrid System. e-4WD consists of a Motor, Inverter, Speed reducer and Clutch. The Motor, Speed reducer and Clutch are installed on the rear sub-frame as a chassis module type. The inverter is installed separately. Compared to a mechanical 4WD, the e-4WD system has many advantages. For example, the reduced number of drivetrain components makes better use of the space. Driving with a motor only at low speed improves fuel economy and reduces exhaust gas. Engine downsizing is available because the motor assists the engine. The performance of a conventional HEV(Hybrid Electric Vehicle) system can also be maintained. This paper proposes the specifications of components and the control logic for an e-4WD System. And the effect of the e-4WD system is proven using a test vehicle equipped with components under various test conditions.

• YAKHAK HOEJI
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• v.5 no.1
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• pp.16-19
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• 1960

Quantitative determination of Arsenic acid by precipitation of Arsenic acid as ZnNH$_{4}$AsO$_{4}$ and titration of Zn in the precipitate by EDTA has been investigated. Conclusion are as follows; 1) ZnNH$_{4}$AsO$_{4}$ was Soluble in NH$_{4}$Cl-NH$_{4}$OH buffer solution of pH lo and back-titration was unnecessary as in the case of MGNH$_{4}$AsO$_{4}$. 2) The end point was clear whether AsO$_{4}$$^{-3}$ present or not. 3) More simple and rapid method than that of Gravi metric method. 4) Could be determined within 0.3% error.

• Archives of Pharmacal Research
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• v.27 no.1
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• pp.19-24
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• 2004

The facile synthesis of a series of 2-(4-hydroxyphenyl)benzofurans (4a-e) is described. The one-pot reaction of 4-substituted phenols with the chloride 1 in the presence of zinc chloride afforded 3-methylthio-2-(4-acetoxyphenyl)benzofurans (2a-e). The compounds 4a-e were obtained from the hydrolysis of 2a-e followed by the desulfurization of the resulting 3-methylthio-2-(4-hydroxyphenyl)benzofurans (3a-e). 5-Methyl-3-p-toluoyl-2 -[4-(3-diethylaminopropoxy)phenyl]benzofuran (7), a $\beta$-amyloid aggregation inhibitor, was synthesized by three steps starting from 4a.

• Bulletin of the Korean Chemical Society
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• v.13 no.3
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• pp.315-316
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• 1992

Sodium (3S,4R)-3-[2-(2-aminothiazol-4-yl)-(Z)-2-methoxyi minoacetamido]-4-methoxymethyl-2-azetidinone-1- sulfonate (2) was synthesized in fourteen steps from D-aspartic acid. Starting from D-aspartic acid, (3S,4R)-3-amino-1-t-butyldimethylsilyl-4-methoxym ethyl-2-azetidinone (12) was synthesized in ten steps. Acylation of the amino group of 12 with $2-amino-{\alpha}-(methoxyimino)-4-thiazoleacetic$ acid, desilylation, sulfonation, and ion exchange afforded sodium (3S,4R)-3-[2-(2-aminothiazol-4-yl)-(Z)-2-methoxyi minoacetamido]-4-methoxymethyl-2-azetidinone-1- sulfonate (2). This new ${\beta}-lactam$ compound 2 showed low antibacterial activities.