• 한국응용과학기술학회지
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• 제8권1호
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• pp.59-67
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• 1991

The reactions of semicarbazide hydrochloride with aliphatic and alicyclic ketones were studied kinetically at 15, 25, 35 and 45$^{\circ}C$ in 20% ethanol solution buffered at pH 2.9. The rate of cyclohexanone semicarbazone formation is 5.5 times as fast as that of cyclopentanone semicarbazone, while 3-pentanone semicarbazone is 4.7 times as slow as that of 2-pentanone, The activation energy of cyclohexanone, 2-pentanone, 2 hexanone, cyclopentanone, 4-methyl-2-pentanone and 3-pentanone semicarbazone formation are calculated 5.08, 7.52, 8.79, 9.59, 9.49, 11.59, respectively. It is concluded from the effect of ionic strength that the reaction is affected by not ion but neutral molecules being progressed hydrogen bond between oxygen atom of carbonyl group and hydrogen atom of acid-catalyst and concerted nucleophilic attack of free base on the carbonly compound. Dependence on pH of the rate of 2-pentanone semicarbozone formation is linear relationship below pH 4.60 and above pH 5.60. As a result of studing citric acid catalysis, second order constants increase linearly with citric acid concentration. As the catalyst concentration is varied from 0.025 to 0.10 mol/1 at pH 2.90, the rate constants increase 1.4 times, but slight increase is observed at pH 5.60. Conclusively, the rate-determining step is formation of tetrahedral interemediate below pH 4.65 and dehydration between pH 5.60 and pH 7.11. It is concluded that the formation reaction of cyclohexanone semicarbazone is faster than cyclopentanone semicarbazone due to the steric strain in the process of forming tetrahedral intermediate.

• 공업화학
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• 제9권7호
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• pp.1079-1084
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• 1998

우레탄 생성반응의 동역학을 조사하기 위해 지방족 이소시아네이트인 4,4'-dihexyl methane diisocyanate($H_{12}MDI$)와 1 관능기 알코올인 n-hexanol간의 반응을 실험적 측정과 수학적 모델링을 통해 연구하였다. 실험은 dibutyltin dilaurate(DBTDL)을 촉매로, 톨루엔을 용매로 온도, 촉매농도, [NCO]/[OH] 비 등을 변화시키면서 실시하였고, 반응동역학은 NCO기와 OH기의 반응에 의한 우레탄 생성반응 및 NCO기와 우레탄간의 반응에 의한 allophanate 생성반응 등 2가지 2차반응식으로 모사하였다. 반응속도상수는 Runge-Kutta 4th order 방법에 의한 전산모사방법으로 계산하였다. 대부분의 조건에서 실험치와 계산치가 잘 일치하여 본 연구에서 제안하는 반응 모델과 속도상수 계산방법이 적절함을 알 수 있었다. 또한 NCO기 90% 전환율에서 allophante/urethane의 비를 계산하였는데 대부분의 조건에서 20% 이상의 높은 값이 얻어져 allophanate 생성반응이 우레탄 물성에 중요한 영향을 미칠 수 있음을 알 수 있었다.

• 한국세라믹학회지
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• 제40권8호
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• pp.758-764
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• 2003

비정질알루미나와 기공형성제를 물과 혼합하여 원통형으로 성형하고 수화, 건조 및 소성하여 ${\gamma}$-alumina pellets을 제조하였다. 촉매 전구체인 Fe(NO$_3$)$_3$ㆍ9$H_2O$의 농도를 일정하게 하면서 $CH_3$COOH의 농도를 2.5~20% 범위로 변화시킨 혼합용액을 제조하고, 여기에 ${\gamma}$-alumina pellets을 침척하여 $200^{\circ}C$ 온도로 3시간 수열처리 한 다음, 결정의 생성 및 변화, 기공특성, $N_2$ 흡/탈차특성, 산점변화 그리고 기계적 강도 등을 조사하였다. $CH_3$COOH 의 농도에 따라 0.5~2${\mu}m$ 길이의 침상으로 결정이 성장하였고, 결정구조는 의사베마이트 구조를 나타냈다. 10% $CH_3$COOH 용액에서 수열처리 했을 때 100~1000$\AA$사이의 기공부피가 0.86cc/g롤 가장 높았으며, 질소 흡탈착 이력곡선의 폭이 가장 작게 나타났다. $CH_3$COOH 농도가 5~15% 범위일 때 새로운 C-H 관능기가 형성되었고, 촉매의 기계적 강도도는 $CH_3$COOH 농도가 2.5%일 때 1.35MPa로 가장 높았다.

• 청정기술
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• 제29권2호
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• pp.79-86
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• 2023

Ru-MACHO-BH 촉매는 α, β-불포화 알데히드 화합물들의 카르보닐기(carbonyl group)만을 선택적으로 수소화 반응을 수행할 수 있다. 그러나 α, β-불포화 알데히드의 수소화 반응은 불균일 딜즈-앨더 반응을 수반하여 부산물인 이합체를 다량 생성한다. 본 연구에서는 Ru-MACHO-BH (Carbonyl hydrido (tetrahydroborato) [bis (2-diphenyl phosphino ethyl) amino] ruthenium(II)) 촉매를 이용하여, α, β-불포화 알데히드의 한 종류인 메타아크릴 알데히드(methacryl aldehyde) 화합물의 카르보닐기만 선택적으로 수소화 반응을 시켜 메타아릴 알코올(methallyl alcohol)을 합성하며, 동시에 2가 알코올을 부반응 억제제로 적용하였다. 이 결과는 모노 에틸렌 글리콜(mono ethylene glycol)이 이합체의 생성을 현저히 저감 시킬 수 있음을 보여주고 있다. 이러한 결과를 바탕으로 비닐기의 화학적 상호작용을 효과적으로 억제할 수 있는 하이드로퀴논을 사용하여 메타아크릴 알데히드에 존재하는 비닐기의 이합체 형성을 효과적으로 억제할 수 있었으며, 결국 메타아크릴 알데히드의 전환율을 상승시킬 수 있었다. 최종적으로, 고가의 귀금속 균일촉매인 Ru-MACHO-BH의 투입량을 1/10로 줄인 상태에서 원하는 생성물인 메타아릴 알코올의 선택도는 약 90% 이상, 수율은 약 80% 이상을 확보할 수 있었다. 이 결과는 수율 감소를 최소화하는 동시에 고가의 촉매 사용량을 저감하여 경제성을 향상시킬 수 있는 방법을 찾을 수 있게 하였다.

• 한국실내디자인학회논문집
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• 제20권6호
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• pp.135-144
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• 2011

This study starts from the question if the characteristic of existing conventional site-specificity can be applied to the modern city space in information media era as it is. The evolution and spread of media technology acted as the catalyst which establishes the identity of an individual and promotes the social sense of belonging as the new type of community member as well as expanded the communication territory of man. Moreover, as the perfect merge of third dimensional space with second dimensional media was accomplished, the meaning of city as the place is getting changed and extended to city space as the information platform which integrates and intermediates the various information composing city. Hereupon, this study is willing to analyze the limits which the characteristics of physical, active and meaningful elements which are the forming primary factors in the existing place theory have and establish the new meaning of city as the place through the case studies which are applied by the characteristics of hyper spacio-temporal, mobility and polysemy as the characteristics transformed by information platformization of city space.

• 한국보육지원학회지
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• 제12권5호
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• pp.91-113
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• 2016

This study aims to find out the significance in the experiences of voluntary participation in small groups by mothers of young children. As a result of the interviews conducted by targeting five mothers, the total was divided into three categories and six sub-factors. First, mothers voluntarily participated in small groups. Free from the role of mother and wife, they focused on their real selves, and had experiences of emotional support by forming close relationships with people. Second, mothers did not just participate in small groups as a hobby, but tried to be role models that help the growth of their children. They also tried to be the catalyst that helps create positive changes in their children and husbands. Third, mothers had social experiences, participated in economic activities as members of society or exerted their capabilities through active exchange with other people. Finally, this research hopes to provide the community with parent education-related implications that can have a positive impact on mothers themselves, their families and society.

• 한국막학회:학술대회논문집
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• 한국막학회 2002년도 제15회 심포지움
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• pp.23-46
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• 2002

The cryogenic, pressure swing adsorption and membrane methods have been used to separate air into nitrogen and oxygen. The air separation membrane is made of the polymers, of which manufacturing process is complicate and it causes a little high production cost. Polymer membrane has temperature limit in usage and low durability even at moderate temperature. Therefore, inorganic membranes have been studied for years. As formation of unit alumino-silicate membrane, unit cells of membrane were made with a few coating methods. In this study the dipping of substrate into sols, application of vacuum to the opposite side of substrate with coating and rotating of the substrate in the sols were found as good coating memthods to make a uniform coating and to control the thickness of membrane. The membrane coats were examined by SEM and XRD. The sample ESZl-1 was compared with those of samples that prepared by another method. The present developed coating methods could be applied to the various types of zeolite membrane formation, that is A- X-, Y- ZSM- and MCM-types of membranes. Also these membrane forming methods could be applied to formation of catalyst absorbed zeolite membrane, of which zeolite absorb the catalytic metals. The product obtained from these coating methods could be applied to the industrial gas and liquid phase catalytic reaction and separation processes.

• Environmental Engineering Research
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• 제20권2호
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• pp.155-161
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• 2015

Experimental research shows that the nitric oxides ($NO_X$) concentration track at the outlet of selective catalytic reduction (SCR) catalyst with a transient variation of Adblue dosage has a time delay and it features a characteristic of resistance-capacitance (RC). The phenomenon brings obstacles to get the simultaneously $NO_X$ expected to be reduced and equi-molar ammonia available to SCR reaction, which finally inhibits $NO_X$ conversion efficiency. Generally, engine loads change frequently, which triggers a rapid changing of Adblue dosage, and it aggravates the air quality that are caused by $NO_X$ emission and ammonia slip. In order to increase the conversion efficiency of $NO_X$ and avoid secondary pollution, the paper gives a comprehensive analysis of the SCR system and tells readers the key factors that affect time delay and RC characteristics. Accordingly, a map of time delay is established and a solution method for time constant and proportional constant is carried out. Finally, the paper accurately describes the input-output state relation of SCR system by using "variable RC model with time delay". The model can be used for a real-time correction of Adblue dosage, which can increase the conversion efficiency of $NO_X$ in SCR system and avoid secondary pollution forming. Obviously, the results of the work discover an avenue for the SCR control strategy.

• Elastomers and Composites
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• 제46권3호
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• pp.257-261
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• 2011

새로운 아스팔트 개질 방법을 소개한다. 일반 아스팔트에 플라스틱 고분자의 단량체인 디메틸페놀(DMP)를 혼입하여 아스팔트 내부에서 외부의 반응촉매 투입 없이 공기 중의 산소분자에 의하여 열가소성 고분자인 폴리페닐렌 옥사이드(PPO)가 자율적으로 중합되면서 아스팔트의 소성변형 내구성이 크게 향상된 개질아스팔트를 얻었다. 인장실험에서, 아스팔트 내에서 생성된 PPO에 의해, 기계적 특성에서 가장 중요한 두 가지 요소인 티네시티와 터프네스가 순수 아스팔트보다 각각 두 배 반 그리고 세 배 가량 증가하였다.

• Bulletin of the Korean Chemical Society
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• 제30권2호
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• pp.309-314
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• 2009

New poly(arylene-ethynylene)s with silicon-containing ferrocene moiety in the polymer main chain were synthesized via the C-C bond forming reactions of 1,1´-bis(ethynyldimethylsilyl)ferrocene and various aromatic dihalides in high yields. The aromatic dihalides include 1,4-dibromobenzene, 4,4´-dibromobiphenyl, 9,10-dibromoanthracene, 2,5-dibromopyridine, 2,5-dibromothiophene, and 2,6-diiodo-4-nitroaniline. The polymer structures and properties were characterized by such instrumental methods as NMR $(^1H-,\;^{13}C-,\;and\;^{29}Si-)$, IR, UV-visible spectroscopies and TGA/DSC. The spectral data indicated that the present polymers have the regular alternating structure of 1,1´-bis(ethynyldimethylsilyl)ferrocenylene and arylene units. The resulting polymers were completely soluble in such organic solvents as methylene chloride, chloroform, benzene, chlorobenzene, and THF. The thermal behaviors of the resulting polymers were examined.