• 대한화학회지
• /
• 제38권5호
• /
• pp.377-381
• /
• 1994

실옥산 사슬과 크라운 에테르가 연결된 유연성이 큰 2가지 새로운 비스-크라운 에테르를 합성하였다. 1,3-Bis(trimethylsiloxy)-1,3-dimethyl-1,3-dipentaoxacyclohexadecamethyl disiloxane(1)는 백금촉매 존재하에서 3-methylene-16-crown-5 (8)과 1,3-bis(trimethylsiloxy)-1,3-dimethyl disiloxane (10)의 반응에 의해 합성하였다. 1,1,3,3,5,5-Hexamethyl-1,5-dipentaoxacyclohexadecamethyl trisiloxane (2)은 백금촉매 존재하에서 crown ether (8)과 1,1,3,3,5,5-hexamethyl trisiloxane (11)의 반응에 의해 합성하였다. 3-Methylene-13-crown-4 (7), 3-methylene-16-crown-5 (8), 및 3-methylene-19-crown-6 (9)은 NaH 존재하에서 triethylene glycol (3), tetraethylene glycol (4), 및 pentaethylene glycol (5)을 각각 3-chloro-2-chloro-methyl-1-propene (6)와 반응시켜서 합성하였다.

• 한국식품과학회지
• /
• 제26권3호
• /
• pp.255-260
• /
• 1994

재래식 메주, 고오지, 나토 메주, 고오지-나토의 혼용 메주를 사용하여 90일 수성시킨 된장의 향기 성분은 다음과 같다. 된장의 향기 성분을 Headspace 방법으로 추출하여 GC-MS로 분석한 결과 36종이 검출되었는데 이중 알콜류 5종, 알데히드류 5종, 케톤류 8종, 유기산류 3종, 에스테르류 9종, 그 외 6종으로 확인되었다. 시험 된장별로는 재래식 된장에서 29종으로 가장 많았고, 고오지 된장과 고오지-나토 된장에서 각각 $26{\sim}24$종, 그리고 나토 된장에서 20종으로 가장 적었다. 관능기별 향기성분 조성비는 각 시험구에서 알콜 함량이 가장 많았으며 재래식 된장은 다른 시험된장 보다 카보닐 화합물, 에스테르 함량비가 높았고 고오지-나토된장에서는 이들의 조성비가 가장 낮았다. 된장의 향기 성분으로 아직까지 제시되지 않은 화합물인 3-ethoxy-1-propene, dihydro-2-methyl-3-furanone, 1-hydroxy-2-propanone, 1-(2-furanyl)ethanone, 2-acetyl-ethylhexanoate 등 5종이 확인되었다.

• 한국식품저장유통학회지
• /
• 제4권3호
• /
• pp.295-300
• /
• 1997

The water extract of mustard seed was fractionated by solvents with an increase of polarity, and antimicrobial activities of each extracts were examined, and volatile compounds of each extract were identified by GC-MS. When the water extract was fractionated with solvents, the antimicrobial activities were high in the order of chloroform, ethylacetate, hexane, butanol and aqueous layer. In chloroform fraction, 16 volatile compounds, including 2 isothiocyanates such as 3-isothiocyanato- 1-propene and 4-isothiocyanato- 1-butane, 1 nitrile and 4 acids were identified, their contents were higher than other fractions. Twelve, 10, 4 and 7 volatile compounds were identified in ethylaceate, hexane, butanol and water fractions, respectively. The volatile compounds were considerably less in the fractions of butanol and water than others.

• 한국대기환경학회지
• /
• 제14권2호
• /
• pp.153-160
• /
• 1998

The concentrations of volatile organic compounds (VOCs) in the atmosphere were measured from the Yochon Industrial Estate and compared with those from Tongkwangyang and Seoul. The first important phenomenon observed in the air of Yochon was high concentrations of alkenes and in particular, ethylene and propene. For most dominant species, their means and standard deviations were high simultaneously. Concentrations of several major aliphatic species exhibited a similar pattern of diurnal variation, however, with different species combination on each day. Concentrations of several hazardous aromatic species also exhibited a similar pattern of diurnal variation on the same day, which was different from that observed in the diurnal variation of major aliphatic species. It was interpreted that some species were intermittently released from relevant processes. It was also understood that high concentrations and variations of VOC species in Yochon were localized and not related to high average concentrations of ozone in Yochon and Tongkwangyang areas.

• Carbon letters
• /
• 제8권1호
• /
• pp.25-29
• /
• 2007

The carbon brake discs were manufactured by densification the carbon fiber preform using PG-CVI technology with Propene as a carbon precursor gas and Nitrogen as a carrier gas. The densities of carbon brake discs were tested at different densification time. The results indicate that the densification rate is more rapid before 100 hrs than after 200 hrs. The CTscanning image and the SEM technology were used to observe the inner subtle structure. CT-images show the density distribution in the carbon brake disc clearly. The carbon brake disk made by PG-CVI is not very uniform. There is a density gradient in the bulk. The high-density part in the carbon brake is really located in the friction surface, especially in the part of inner circle. This density distribution is most suitable for the stator disc.

• Bulletin of the Korean Chemical Society
• /
• 제13권1호
• /
• pp.65-70
• /
• 1992

The hindered internal rotation effect of methyl group on chemical reaction was studied for cis-trans isomerization reaction of 1-bromopropene system using RRKM technique. A comparative study of the isomerization rates was also performed between the rigid and allowed internal rotations. The calculated rate of rigid cis-trans isomerization of 1-bromopropene was shown to be three times higher than its other halogenated propene homologues with its internal rotations and found to be in good agreement with experimental observations. These findings could be explained reasonably well in terms of the differences of the rotational barrier heights among halogenated propenes and correlated with the relatively low internal rotation barrier of cis-1-bromopropene, 230 cal/mol, compared to those of other cis-1-halopropenes, 700-800 cal/mol, and trans-1-halopropenes, 2.0-2.4 kcal/mol.

• Bulletin of the Korean Chemical Society
• /
• 제16권5호
• /
• pp.443-449
• /
• 1995

N-(Isopropyloxycarbonyloxy)maleimide (iPOCMI) has been synthesized and polymerized to give both the homopolymer and copolymers with substituted styrenes. These polymers were readily deprotected by thermolysis of the isopropyloxycarbonyl (iPOC) groups to provide the corresponding N-hydroxymaleimide (HOMI) polymers. The homopolymer and styrenic copolymers of iPOCMI were radically obtained in higher conversion and higher molecular weight than those obtained by direct polymerizations of N-hydroxymaleimide. The homopolymer of iPOCMI was transformed into poly(N-hydroxymaleimide)P(HOMI) by thermolysis of iPOC groups at 205 $^{\circ}C$ with concurrent release of propene and carbon dioxide. The copolymer of iPOCMI and styrene was thermally deprotected to the copolymer of HOMI and styrene at 235 $^{\circ}C.$ The mass loss was 28% and the Tg of the resulting copolymer was 250 $^{\circ}C.$ The thermal deprotection readily provided the desired, polar HOMI polymers which have Tgs above 240 $^{\circ}C.$ The deprotection was accompanied by large changes in aqueous base solubility.

• Bulletin of the Korean Chemical Society
• /
• 제7권4호
• /
• pp.279-282
• /
• 1986

The MNDO calculations were performed in order to investigate the gas-phase reaction mechanism of 2-propene-1-al oxide, as a model compound of dypnone oxide(1,3-diphenyl-2-butene-1-one oxide) with the chloride ion. Optimized geometries and heats of formation for two probable concerted pathways, CHO and H migration, were determined and their activation energies were obtained. MO results show that although the formyl migration is thermodynamically more favorable than the hydride migration, the latter kinetically predominates over the formyl migration, which is contrary to the established migrating preferences. It is concluded that the hydride migratory propensity is catalyzed by the chloride ion by reducing the capability of the carbonyl ${\pi}$ bond to participate in the migration.

• 한국식품저장유통학회지
• /
• 제23권3호
• /
• pp.369-377
• /
• 2016

본 연구는 과열증기처리 기술을 양파에 적용하여 불쾌취를 저감화하고, 이를 통해 고품질 양파 가공품 개발 및 소재화에 활용하기 위한 기초 자료를 확보하고자 과열증기처리에 따른 양파의 휘발성 물질, 불쾌취 유발 물질과 항산화활성, 조직감, 관능적 특성 등 품질특성을 분석하였다. 과열증기처리에 의해 휘발성 향기성분 및 불쾌취와 매운맛의 지표 물질이 저감화됨을 확인하였다. 항산화활성 및 총 페놀성 화합물 함량은 다소 증가하는 경향을 보였으며, hardness, chewiness 등은 확연하게 감소하는 것으로 나타났다. 양파 추출액의 총 가용성 고형분 함량은 처리에 의해 전체적으로 증가하였으며 처리에 따라 기호도 점수가 높아지는 것을 확인하였다. 결과적으로 과열증기 처리가 양파의 불쾌취저감화에 효과적임을 확인할 수 있었다. 본 연구결과는 과열증기 기술을 적용한 양파의 불쾌취 저감화 및 이를 통한 다양한 고품질 가공품 개발 및 소재화를 위한 중요한 기초 자료로 활용될 수 있으리라 판단되며, 과열증기오븐 처리를 통해 불쾌취를 조절함과 동시에 생리활성능을 지니는 향기 성분 및 유용성분의 감소는 최소화하는 추가적인 연구가 필요할 것으로 사료된다.

• 한국식품영양과학회지
• /
• 제31권4호
• /
• pp.566-571
• /
• 2002

명태식해의 산업화를 위한 기초자료를 제시하기 위해 명태식해를 제조한 뒤 저온(5$^{\circ}C$)에서의 저장 중 휘발성 향기성분을 LLCE/GC/MS법으로 분석한 결과 총 65종의 화합물이 검출되었다. 이는 주로 함황화합물류(11종), 알콜류(13종), acid류(13종), 알데히드류(4종), 케톤류(4종), 테르펜류(6종), 방향족 화합물류(4종) 및 기타 화합물류(10종)로 구성되어 있었다. 한편 명태식해 숙성 중 함황화합물류(3-(methylthio)-1-propene, dimethyl disulfide, diallyl sulfide, methylallyl disulfide, methyl-(E)-propenyl disulfide, dimethyl trisulfide, 2 diallyl disulfide isomers, diallyl trisulfide), 산류(acetic acid, butanoic acid), 케톤류(2, 3-butanedione, 6-methyl-5-hepten-2-one) 및 기타 화합물류 중의 에스테르류(ethyl formate, ethyl acetate)가 저장기간에 따라 유의적으로 증가하는 경향을 나타내고 있었다(p<0.05). 특히 함황화합물류는 명태식해의 숙성과정 전반에 걸쳐 영향을 미칠 것으로 추정되었고, acid류, 케톤류 및 에스테르화합물류는 숙성 후반에 더 크게 관여할 것으로 추정되었다.