• 한국추진공학회:학술대회논문집
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• 한국추진공학회 2017년도 제48회 춘계학술대회논문집
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• pp.168-171
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• 2017

X-ray photoelectron spectroscopy(XPS) 분석법을 이용하여 FKM O-ring의 대기중에서의 노화 메카니즘을 관찰하였다. FKM O-ring은 선경 3.53mm, 내경 91.67mm인 오링을 시편으로 사용하였다. 노화 후 FKM O-ring의 oxygen 원소의 농도가 20.39%로 증가하였으며, fluorine 원소는 각각 8.29%로 감소하는 경향을 나타내었다. 이를 통하여 산소에 의한 산화 반응이 FKM O-ring의 주요 노화 반응으로 나타났다. C1s와 F1s 피크 분석 결과, FKM O-ring의 주쇄중 C-F 결합에서 산화 반응이 주로 진행되는 것으로 나타났다. 또한 O1s 피크 분석 결과, 산화 반응을 통하여 C-OH, C=O, 그리고 O=C-O 구조를 형성하며, 주로 카르복실기가 생성되는 것으로 나타났다.

• KIEE International Transactions on Electrophysics and Applications
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• 제11C권4호
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• pp.133-137
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• 2001

In this research, we synthesized various photo-crosslinkable polyimide based polymers. The control of pretilt angles for a nematic liquid crystal (NLC) using the photodimerization method on the photopolymers was studied. A good thermal stability of the photopolymers was measured by thermogravimetric analysis (TGA) measurement until 450C. High pretilt angles of the NLC were otained by polarized UV exposure on the photopolymers containing biphenyl (BP), decyl (de), and cholesteryl (chal) groups, respectively. However, low pretilt angles of the NLC were measured by polarized UV exposure on the photopolymers containing fluorine and chalcone groups. The high NLC pretilt angles generated are attributable to the biphenyl and alkyl moieties, and the photodimerized chalocone group of the photopolymers. Additionally, good voltage-transmittance and response time characteristics were observed by UV exposure on the photopolymers.

• 한국환경보건학회지
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• 제13권1호
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• pp.7-16
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• 1987

A study was carried out to determine the adequacy of springs as drinking water in summer and in winter separately. In this study, environmental sanitation, physio-chemical examination, bacteriologic contamination and the content of heavy metal were included. For this study, samples were collected from 8 springs which were located in the suburbs of Chunchon city. The following results were obtained. 1. There was the covering system in 1 out of 8 springs. 6 out of 8 springs showed contaminating source within lorn. 2. In physio-chemical test, six out of 8 springs were found to be unsafe for the legitimate standard of safty water. 3. Bateriologic examination clone during summer showed the evidence of coilform group at 7 out of 8 springs and during winter showed positivity at 3 out of 8 springs. 4. In the study for heavy metal content, all places showed high iron level beyond the standard level of salty water, and 4 places showed high contents of fluorine, mangan and lead.

• Archives of Pharmacal Research
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• 제21권3호
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• pp.338-343
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• 1998

$2^1$-Fluorohexopyranosyl nucleosides 1a and 1b which contained a bioisosteric double bond and a fluorine were synthesized in 12 steps, starting from D-galactose. During diethylaminosulfur trifluoride (DAST) fluorination, retention of stereochemistry was observed through the participation of methoxy or chloro group at the 6-posiition of the purine base. The final nucleosides 1a and 1b were found to be inactive against HIV-1 and HSV-1,2.

• 한국막학회:학술대회논문집
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• 한국막학회 1994년도 춘계 총회 및 학술발표회
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• pp.53-54
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• 1994

Polyimide는 열, 화학적으로 안정하고 기계적성질이 우수하고, 기체분리특성이 비교적 좋다. Polyimide의 화학구조와 기체투과도와의 관계는 화학구조를 체계적으로 변화시키면서 많이 검토되어왔다.[1-2] Polyimide는 강직한 직쇄구조, bulky group에 의한 분자쇄운동성을 제어함과 동시, 약한 분자간 상호작용이 polymer chain의 유효층진을 억제하여 기체투과도를 높여준다. 국부분절운동(local segmental mobility)이 감소된 구조는 기체투과선택도를 향상시켜주는 경향을 보여주었다. [3] kim et al. 과 Stern et al은 6FDA나 fluorine-containing diamines으로 만든 polyimde가 매우높은 투과도를 보여준다고 보고했다. 본 연구에서는 6FDA-2, 4TDA hobopolymer에 BAAF를 가하여 copolyimide Membrane을 제막하여 BAAF 조성에 따라 투과선택도를 측정하는 homopolymer와 copolymer에 따른 변화를 관찰하였다.

• Bulletin of the Korean Chemical Society
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• 제31권10호
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• pp.2783-2785
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• 2010

Searching for new molecular radicals which are believed to play an important role as reaction intermediates in aromatic chain reactions, we have applied the technique of corona excited supersonic expansion employing a pinhole-type glass nozzle to obtain the vibronic spectrum from the corona discharge of precursor 3,5-difluorotoluene with a large amount of inert carrier gas helium. An analysis of the observed spectrum revealed that many vibronic bands are from other isomeric difluorobenzyl radicals generated in the jet by migration of the fluorine atom or methylene group to the adjacent position in the 3,5-difluorobenzyl radical. A possible mechanism was proposed for the formation of other isomers by using a bridged cyclic intermediate structure.

• Bulletin of the Korean Chemical Society
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• 제17권7호
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• pp.599-604
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• 1996

The synthesis is reported of p-nitrophenyl glycosides of D-galactose modified at C-4 with azido- (5), amino- (6) group and fluorine (13). 4-Azido-2,3,6-tri-O-benzoyl-4-deoxy-α-D-galactopyranosyl chloride and 2,3,6-tri-O-benzoyl-4-deoxy-4-fluoro-α-D-galactopyranosyl bromide were coupled with potassium p-nitrophenoxide in the presence of 18-crown-6 giving the corresponding p-nitrophenyl 4-azido-and 4-fluoro-4-deoxy-β-D-galactopyranoside derivatives. p-Nitrophenyl 4-amino-4-deoxy-β-D-galactopyranoside (6) was obtained by selective reduction of p-nitrophenyl 4-azido-4-deoxy-β-D-galactopyranoside (5) using 1,3-propane dithioltriethylamine. These galactoside analogs were slowly hydrolyzed in the increasing rate order of 5, 6 and 13 by β-galactosidase from Escherichia coli.

• 한국추진공학회지
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• 제20권5호
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• pp.40-50
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• 2016

현재 적용되고 있는 에너지화 가소제는 $-NO_2$, $-ONO_2$ 및 $-N_3$와 같은 에너지화 활성 그룹을 포함하고 있어서 충격, 쇼크, 열 등 외부환경에 상당히 민감하여 복합화약의 둔감 안정성을 취약하게 한다. 본 연구에서는 민감한 에너지화 활성 그룹이 아니라 근본적으로는 비활성 그룹으로 복합화약의 민감도에는 영향을 미치지 않지만, 복합화약의 반응 시에 테르밋반응에 의해 추가적인 에너지를 발생할 수 있는 불소계 반응성 가소제를 적용한 폴리우레탄 결합제를 클릭반응으로 합성하고 나노 알루미늄과의 테르밋반응에 대한 열적 특성을 고찰하였다.

• 한국표면공학회지
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• 제54권6호
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• pp.357-364
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• 2021

In this study, DLC films deposited by PECVD were evaluated to the properties of super-hydrophobic by CF₄ treatment. The structure of DLC films were confirmed by Raman Spectra whether or not mixed sp³ (like diamond) peak and sp² (like graphite) peak. And the hydrogen contents in the DLC films (F-DLC) were measured by RBS analysis. In addition, DLC films were analyzed by scratch test for adhesion, nano-indentation for hardness and tribo-meter of Ball-on-disc type for friction coefficient. In the result of analysis, DLC films had traditional structure regardless of variation of hardness at constant conditions. Also adhesion of DLC film was increased as higher material hardness. Otherwise, friction coefficient was increased as lower material hardness. The DLC films were treated by CF₄ plasma treatment to enhance the properties of super-hydrophobic. And the DLC films were measured by ESEM(Enviromental Scanning Electron Microscope) for water condensation.

• 한국치위생학회지
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• 제10권2호
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• pp.231-242
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• 2010

Objectives : The purpose of this study was to examine the relationship of oral health behavior factors to oral health promotion behavior in dental hygiene students and nonhealth-related majors, to identify factors affecting their oral health promotion behavior and ultimately to provide information on the oral health promotion of college students and behavioral factors related to that. Methods : The subjects in this study were three-year-course dental hygiene students and two-year-course nonhealth-related majors in G college located in the city of Gwangju. A self-administered survey was conducted for 11 days from September 9 to 19, 2009, and the answer sheets from 473 respondents were analyzed. To look for connections between their major and the characteristics of their oral health promotion behavior, t-test was utilized, and t-test and one-way ANOVA were carried out to find out the relationship oral health promotion behavior by general characteristics. Besides, multiple regression analysis was employed to grasp factors affecting oral health promotion behavior. Results : Among the subfactors of oral health promotion behavior, the dental hygiene students statistically significantly outdid the nonhealth-related majors in thorough post-meal toothbrushing(p<0.01), toothbrushing method(p<0.001), use of fluorine-containing dentifrice(p<0.001) and good nutrition(p<0.05). But the latter statistically significantly outperformed the former in use of fluorine-containing rinse(p<0.001) and limited sugar intake(0<0.05). Regarding variables affecting oral health promotion behavior, the age group, whether to get a dental checkup over the last year and whether to use oral hygiene supplies were identified as the variables to impact on oral health promotion behavior. Specifically, the age group(dental hygiene students) and the get a dental checkup over the last year(nonhealth-related majors) had a greater impact. Conclusions : To promote the oral health of college students, comprehensive oral health education should be provided, which covers the importance of dental checkup, recommendation for the use of oral hygiene supplies, etc. Specifically, oral health education should be offered as one of general education courses in order for nonhealth-related majors to get into sound life habits and improve their oral health promotion behavior. To make it happen, required institutional measures should be taken.