• Elastomers and Composites
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• v.43 no.4
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• pp.271-280
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• 2008

Aromatic polyhydroxyamides (PHAs) having bulky groups and ether linkages in the polymer main chain were synthesized by the low temperature solution polycondensation reaction. FT-IR, $^{1}H-NMR$, DSC, and TGA were used to study the properties of these polymers. The PHAs were converted into polybenzoxazoles (PBOs) by a thermal cyclization reaction, and endothermic peaks were observed in the range of $220{\sim}400^{\circ}C$. The introduction of the ether and bulky groups in the main chain improved the solubility of the PHAs in aprotic solvents such as DMSO and DMF, but the PBOs were nearly insoluble in common solvents. All the PBOs, except for PBO 5 with 2,6-dimethylphenoxy pendant and 2,3-dihydroxyquinoxaline ring, and PBO 6 with 2,6-dimethylphenoxy pendant and 2,3-dihydroxyquinoxaline ring, exhibited $T_g's$ in the range from 149 to $217^{\circ}C$ by DSC. The thermogravimetric analyses indicated that most of the PBOs were thermally stable up to $400^{\circ}C$ in nitrogen. Maximum weight loss temperatures of PHA 5 and PBO 5 with 2,6-dimethylphenoxy pendant and 2,3-dihydroxyquinoxaline ring were $707^{\circ}C$ and $683^{\circ}C$, respectively, which were the hightest temperatures among the corresponding copolymers. The PBOs in nitrogen exhibited relatively high char yields in the range of $63{\sim}70%$ at $900^{\circ}C$.

• Journal of the Korean Chemical Society
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• v.34 no.5
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• pp.469-475
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• 1990

The reaction of 2,6-dichloroquinoxaline (13) with m-chloroperbenzoic acid gave 2,6-dichloroquinoxaline 4-oxide (14), whose reaction with pyrrolidine or indoline provided 2-substituted 6-chloroquinoxaline 4-oxides (15). The isoxazolo[2,3-a]quinoxalines (16) and pyrrolo[1,2-a]quinoxalines (17) were selectively synthesized from the 2-substituted 6-chloroquinoxaline 4-oxides (15) and dimethyl acetylenedicarboxylate. Moreover, the pyrrolo[1,2-a]quinoxalines (17) were found to be produced by the ring transformation of the isoxazolo[2,3-a]quinoxalines (16).

• Korean Journal of Crystallography
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• v.5 no.2
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• pp.100-107
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• 1994

A new Nl-pentenyl derivative of pyrimidines has been synthesized by an intramolecular (2+2) photocycloaddition and characterized by the single-crystal X-ray diffraction technique. The compound crystallizes in the rhombohedral system (R3, a=27.767(5)A c=6.390(2)A). In this structure, two 6-membered rings and a 4-membered ring are fused by the N-N or N-C bonds and the Tyidin Part adouts chair conformation. A pair of molecules related by an inversion center we held together through the hydrogen bonding interactions between N and O atoms of the uracil miety.

• Analytical Science and Technology
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• v.11 no.4
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• pp.292-296
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• 1998

Normal phase or reversed phase liquid chromatographic separation of isoquinoline of heterocyclic compounds and structural isomers of external substituents, $COOCH_3$, CN and $CH_3$ has been carried out by using several different columns and various mobile phases. From this results, the order of elution of heterocyclic compounds appears to depend on the solvent effect with kinds of mobile phases. Retention mechanism of normal phase system for 2-methylindoline, 2-methylindole, benzoxazole and benzothiazole was also studied depending on adsorption strength between solute and stationary phase of column. However, retention factors of reversed phase system were found on hydrophobic interaction with solvophobic effect.

• Proceedings of the Korean Information Science Society Conference
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• 2007.10c
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• pp.546-551
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• 2007

소프트웨어 버스마크는 프로그램을 식별하는데 사용될 수 있는 프로그램의 고유한 특징을 말한다. 본 논문에서는 windows PE(Portable Executable) 파일의 API에 대한 정보를 가지는 임포트 테이블에 기반한 프로그램 버스마킹 기법을 제안한다. 버스마크의 신뢰도를 높이기 위한 방법으로 대부분의 Windows 프로그램에서 사용되는 범용의 API는 버스마크에서 제외시키고 프로그램 개개의 특성을 나타낼 수 있는 특화된 API에 초점을 맞추어서 비교하는 방법을 사용한다. 본 논문에서 제안한 버스마킹 기법을 평가하기 위해서 다양한 카테고리의 Windows 프로그램에 대해서 실험을 하였다. 신뢰도를 측정하기 위해서 같은 프로그램에 대해서 버전별로 비교를 하였고, 프로그램의 분류에 따라서 유사한 카테고리와 다른 카테고리에 대해서 비교를 하였다. 프로그램의 변환이나 난독화에도 견딜 수 있는 강인도(Resilience)를 평가하기 위해서 서로 다른 컴파일러를 사용하여 생성된 프로그램에 대해서 비교를 하였다. 실험 결과에서 본 논문에서 제안하는 버스마크가 프로그램의 특징을 충분히 표현하고 있음을 보여준다.

• Journal of the Korean Chemical Society
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• v.34 no.6
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• pp.641-645
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• 1990

Ethanolic tetracarbonylhydridoferrate, HFe(CO)$_4^-$, combined with aqueous succinaldehyde is very efficient for the selective transformation of an amino group into a pyrrolidine ring. Phenylendiamines react with aqueous succinaldehyde in the presence of HFe(CO)$_4^-$, at room temperature under atmospheric pressure of carbon monoxide to give the corresponding pyrrolidines in moderate yields. In these reactions, the molar ratio of 1.0:1.0:1.0 of the ferrate-succinaldehydephenylenediamine system gave one pyrrolidine ring, and the case of 1.0:2.0:1.0 gave two pyrrolidine rings, selectively.

• Journal of Convergence for Information Technology
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• v.10 no.10
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• pp.143-149
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• 2020

This study tried to observe the ability to inhibit vasocontriction in phloretin - the primary ingredient of apple tree leaves and the Manchurian apricot - through ROCK(Rho-associdated, coiled-coil containing protein kinase) inactivation in rat aortae. A piece of artery that was separated from Sprague-Dawley male rats and retained or damaged the endothelium was suspended in myograph tank with two metal rings, the lower ring fixed to the bottom of the tank, and the upper ring connected to the isotonic force transducer. Interestingly, phloretin inhibited fluoride- or phorbol ester-provoked contraction implying that additional pathways dissimilar from endothelial nitric oxide synthesis such as ROCK or MEK (mitogen activated protein kinase kinase) inactivation might be involved in the vasorelaxation. Therefore, this study provides that phloretin participates in the reduction of ROCK or MEK activity in smooth muscle in addition to the endothelial-dependent action of the endotheliuim in complete blood vessels, and consequently inhibits actin-myosin interaction in smooth muscle. Furthermore, phloretin inhibited thromboxane A2-induced contraction suggesting the mechanism including inhibition of ROCK and MEK.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.16 no.3
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• pp.377-387
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• 2018

Korea's first commercial nuclear power plant, Kori Unit 1, was permanently shut down on June 18, 2017, after 40 years of successful operation. Kori Unit 1 plans to construct a waste treatment facility in the turbine building prior to commencement of dismantling in earnest. Various radioactive wastes are decontaminated, disassembled, cut and melted in the waste treatment facility and sent to the radioactive waste repository. The proportion of metal radioactive waste in dismantled waste is about 70%, of which large metal radioactive waste is mainly generated in the primary circuit and has high radioactivity, so radiation exposure must be managed during disassembly. In this study, the steam generators are selected as large metal radioactive waste, the exposure doses of the dismantling workers are calculated using RESRAD-RECYCLE code and the methods for reducing the exposure doses are suggested.

• Journal of the Korean Chemical Society
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• v.48 no.4
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• pp.451-455
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• 2004

• Journal of the Korean Chemical Society
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• v.49 no.2
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• pp.173-181
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• 2005