• Bulletin of the Korean Chemical Society
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• 제20권3호
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• pp.341-344
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• 1999

The hydrazones of 2-acetylfuran, 2-acetylthiophene, and 2-acetylpyrrole, were allowed to react with S-methylthioacetimidate hydroiodide (8) to give azinoureas 10, and the reaction of 10 with Appel's dehydration conditions (triphenylphosphine/carbon tetrachloride/triethylamine) led to the corresponding azinocarbodiimides 11, which underwent thermal rearrangement under the reaction conditions to give 1,1-diheteroaryl ethylenes 13.

• 한국응용과학기술학회지
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• 제30권1호
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• pp.9-15
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• 2013

A new process for the synthesis of polyphenylcarbosilane (PPCS) via thermal rearrangement of polymethylphenylsilane (PMPS) in supercritical cyclohexane was proposed and investigated at reaction temperatures of $380-420^{\circ}C$, reaction times of 1-2 h, and a pressure of 15 MPa. The structure, molecular weight, and molecular weight distribution of the product were characterized by FT-IR, Si-NMR, and GPC. The ceramic yield was also measured by TGA analysis. High-quality PPCS with high molecular weight and ceramic yield can be synthesized via a supercritical process. Furthermore, this process, when compared to the conventional method, tends to moderate the reaction conditions such as reaction temperature and time. It is concluded that thermal rearrangement in supercritical fluid is an efficient and viable process in terms of the resulting yield, efficiency, and reaction time compared with those of the conventional PCS production process.

• EDISON SW 활용 경진대회 논문집
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• 제3회(2014년)
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• pp.337-346
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• 2014

Trifluoromethylthiol functional group(이하 -SCF3)은 약학적으로 유용한 물질이다. 이 연구는 최근 개발된 Shibata의 Direct trifluoromethylthiolation reaction의 반응 메커니즘을 계산화학적으로 평가했다. 반응 메커니즘은 크게 Carbene formation, Rearrangement, Electrophilic SCF3 reagent generation 세 단계로 나눌 수 있다. 각 과정에 대해 구조에 대한 full optimization이 진행되었고, 특히 alpha-carbene sulfonyl species의 thermal rearrangement에 관한 첫번째 계산화학적 평가가 이루어졌다.

• Bulletin of the Korean Chemical Society
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• 제17권5호
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• pp.485-487
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• 1996

• 한국분말재료학회지
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• 제5권2호
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• pp.89-97
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• 1998

Sintering behavior of nanostructured(NS) W-Cu powders prepared by mechanical alloying (MA) was investigated as a function of sintering temperature. MA NS W-2owt%Cu and W-3owt%Cu composite powders with the crystal size of 20-30 nm were annealed at 90$0^{\circ}C$, and thermal characteristics of those powders were investigated by DSC. Sintering behavior of MA NS W-Cu composite powders was investigated during the solid-state sintering and the Cu-liquid phase sintering. The new nanosintering phenonenon of MA W-Cu powders at solid-state sintering temperature was suggested to explain the W-grain growth in the inside of MA powders. The sintering densification of MA NS W-Cu powders was enhanced at Cu melting temperature by arrangement of MA powders, i.e., the first rearrangement of MA powders was occurred, and then the rearrangement of W-grains in the sintered parts was also took place during liquid-phase sintering, i.e., the second rearrangement was happened. Due to the double rearrangement process of MA NS W-Cu powders, the high sintered density with more than 96%o was obtained and the fine and high homogeneous state of W and Cu phases was achieved by sintering at 1200 $^{\circ}C$.

• 동력기계공학회지
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• 제13권6호
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• pp.35-42
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• 2009

The piping systems in the steam-driven power engines lie under the cyclic condition of thermal expansion and contraction by superheated steam. These phenomena might cause some severe damages on the pipes and the accessory devices. To avoid these damages, the calculation of the proper strength and the consideration of the reduced resultant forces on the materials are needed. In the present study, numerical investigations on the effects of the thermal deformation of the industrial piping system were performed with comparison of the design data. Commercial software, ABAQUS with the thermal-fluidic loadings based on the design conditions was used for the thermal stress analysis of the piping system. From the analysis of the initially-designed pipe supporters, the rearrangement was suggested to improve the piping design.

• 한국세라믹학회지
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• 제29권12호
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• pp.956-962
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• 1992

The predominant sintering mechanisms of low firing temperature ceramic substrate which consists of borosilicate glass containing alumina as a filler are the rearrangement of alumina particles and the viscous flow of glass powders. In this system, sintering condition depends on the volume ratio of alumina to glass and on the particle size. When the substrate contains about 35 vol% alumina filler and the average alumina particle size is 4 $\mu\textrm{m}$, the best firing condition is obtained at the temperature range of 900∼1000$^{\circ}C$. The extensive rearrangement behavior occurs at these conditions, and the optimum sintering condition is attained by smaller size of glass particles, too. The formation of cristobalite during sintering causes the difference of thermal expansion coefficient between the substrate and Si chip. This phenomenon degradates the capacity of Si chip. Therefore, the crystallization should be prevented. In the alumina filled borosilicate glass system, the crystallization does not occur. This effect may have some relation with aluminum ions in alumina. For aluminum ions diffuse into glass matrix during sintering, functiong as network former.

• Macromolecular Research
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• 제17권9호
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• pp.697-702
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• 2009

Mesoporous ethanesilica thin film was prepared using PEO-PLGA-PEO triblock copolymers as structure-directing agents and (1,2-bis(triethoxysilyl) ethane BTESE; bridged organosilicates) as inorganic precursors via one-step sol-gel condensation of ethanesilica precursors. The mesostructure of ethanesilica films is critically dependent on the processing experimental parameters after the hydrolyzed silica sol mixture was spin-cast. This study examined the effects of the block copolymer template/organosilica precursor ratio in the casting solution and aging period before calcination of the mesostructure. It was further demonstrated that mesoscopic ordering of organosilicate thin films is induced by the rearrangement of block copolymer template/organosilica hybrid during thermal decomposition of the PEO-PLGA-PEO triblock copolymer. The mesoporous structure and morphology were characterized by SAXS, TEM and solid-state NMR measurement.

• Bulletin of the Korean Chemical Society
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• 제22권9호
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• pp.999-1004
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• 2001

(1-Chloro-2,2-dicyanovinyl)benzene or 1,4-bis(1-chloro-2,2-dicyanovinyl)benzene was reacted with 2-amino-phenol to give the model compound, hydroxy enaminonitrile, which was found to undergo thermal cyclization reaction to form the corresponding benzoxazole. This intramolecular cyclization reaction is expected to occur through nucleophilic attack to electropositive enamine carbon by ortho-hydroxy group on the phenyl ring, which is accompanied by the release of neutral malononitrile through rearrangement. From each bifunctional monomer, o-hydroxy substituted polyenaminonitrile was prepared and characterized as a new precursor polymer for well-known aromatic polybenzoxazole. Also the unusual macrocyclic dimer formation from the 1,4-bis(1-chloro-2,2-dicyanovinyl)benzene and 2,2-bis(3-amino-4-hydroxyphenyl)hexafluoropropane polymerization reaction system was discussed. The thermal cyclization reactions and the properties of polymers were investigated using FT-IR and thermal analysis (DSC & TGA).

• 대한화학회지
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• 제22권3호
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• pp.158-163
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• 1978

1-위치에 두개의 극성치환체를 가진 2-비닐시클로프로판 1a, 1b, 1c, 1d를 300$^{\circ}C$ 이하로 가열한 결과 4,4-위치에 치환된 대응하는 시클로펜텐 2a, 2b, 2c, 2d로의 자리 옮김반응이 용이하게 일어났다. 시아노기가 치환된 1b는 용매로 희석시켜서 170${\circ}C$로 반응시켰을 때 2b로의 자리옮김이 관찰되었지만, 1c와 1d는 $200^{\circ}C$ 이상의 온도에서 반응이 일어났고, 페닐기가 치환된 1a는 $250{\circ}C$ 이상의 온도에서 반응이 일어났고, 페닐기가 치환된 1a는 250$^{\circ}C$ 에서 용매 사용없이 열반응으로 2a가 생성되었다. 1a의 시클로펜텐으로의 열적 자리옮김반응은 거의 정량적이었지만 1b, 1c, 1d의 경우에는 시클로펜텐외에 상당량의 고분자물질 3이 생성되었다. 1c의 경우에는 시클로펜텐외에 시클로프로판 고리가 열린 디엔 4가 관찰되었다. 두 기가 치환된 시클로프로판 1이 용이하게 시클로펜텐 2로 열적 자리옮김 반응을 하는 이유는 두 극성기가 반응 중간물질인 디라디칼 5를 안정화 시키는 효과로서 설명하였다.