• Proceedings of the Korea Air Pollution Research Association Conference
• /
• 2009.10a
• /
• pp.480-481
• /
• 2009

• Applied Biological Chemistry
• /
• v.42 no.4
• /
• pp.330-335
• /
• 1999

Pentachlorophenol(PCP), which is very persistent in soil and water environment, was tried to detoxify with oxidoreductive catalysts(peroxidase, laccase, tyrosinase and birnessite). To find out detoxification of PCP, the transformation of PCP through oxidative coupling was investigated in the presence of various oxidoreductive catalysts. PCP incubated with peroxidase was significantly transformed, however, in case of tyrosinase, the transformation was negligible. Using peroxidase, the optimal reaction condition was pH 5.6 and $16^{\circ}C$. The transformation of PCP was very fast in initiation step until 30 min but, that was not observed after 180 min. The transformation of PCP was increased by increasing peroacidase amount. When the effect of humic monomer was investigated as co-substrate on the transformation of PCP, the transformation of PCP was mostly decreased in the incubation with peroxidase, laccase, and birnessite. The transformation of PCP, however, was slightly increased by the incubation with tyrosinase in the presence of humic monomers as co-substrate, except catechol. On the basis of the results obtained, it may be suggested that PCP is able to be effectively detoxified through oxidative coupling mediated with oxidoreductive catalysts.

• Journal of Life Science
• /
• v.14 no.2
• /
• pp.269-274
• /
• 2004

Using heterogeneous catalyst, esterification reaction of soybean oil (SBO) with methanol was investigated. Distributions of components in mixtures of soybean oil and methanol were measured at temperatures ranging from 40 to $65^{\circ}C$. Glycerine contents of reaction mixtures were measured for the different kinds of catalysts, such as NaOH, CaO, Ca(OH)$_2$, MgO, Mg(OH)$_2$, and Ba(OH)$_2$. Based on the measured glycerine concentrations, conversions of the reaction mixtures were calculated. The effects of dose of catalyst, cosolvent and reaction temperature on final conversion were examined. Solubility of methanol in soybean oil was substantially greater than that of soybean oil in methanol. When the esterification reaction of soybean oil was catalyzed by heterogeneous catalyst, final conversion was strongly dependent on the alkalinity of the heterogeneous catalyst, and increased with the alkalinity of the catalyst material. Hydroxides from the alkali metals were more effective than oxides, which actually had no catalytic effects. When Ca(OH)$_2$ was used for the esterification catalyst, maximum value of final conversion was measured at dose of 4%. The final conversion and reaction rate increased with reaction temperature, and showed substantial increment at reaction temperature of 5$0^{\circ}C$. When cosolvent, CHCl$_3$, was added into the reaction mixture of soybean oil which catalyzed by Ba(OH)$_2$, maximum value of final conversion was appeared at dose of 3%.

• Transactions of the Korean Society of Automotive Engineers
• /
• v.9 no.6
• /
• pp.103-111
• /
• 2001

During cold-start period, the reduction of exhaust emissions is a challenging task. To decrease harmful gaseous substances such as HC, it is necessary to realize a fast catalyst warm-up. In this study, the performance of dual pipe exhaust system have been carried out through different test mode. From measurement of gas temperature and HC concentration, the following conclusions were derived ; 1) Compared with single pipe, dual pipe exhaust system remarkably increase temperature of exhaust gas going through M.C.C(Main Catalytic Converter). 2) W.C.C.(Warm-up Catalytic Converter) also decreases HC emission. To reduce HC emission, it is helpful to use W.C.C. as well as dual pipe exhaust system. 3) Using finite element method, it is shown that inner parts have much higher distribution of temperature than outer parts.

• Journal of the Korean Electrochemical Society
• /
• v.15 no.2
• /
• pp.74-82
• /
• 2012

Proton exchange membrane fuel cell performance is changed by the complicated physical phenomenon. In this study, water discharge performance of proton exchange membrane fuel cell were performed numerically to compare serpentine channel flow fields of 5-pass 4-turn serpentine and 25 $cm^2$ reaction surface between with and without sub-channel at the rib. Through the supplement of sub channel flow field, it is shown from the results that water removal characteristic inside channel improves because the flow direction of under-rib convection is changed into the sub channel. Reacting gases supplied from entrance disperse into sub channel flow field and electrochemical reaction occurs uniformly over the reaction surface. The results obtained that total current density distributions become uniform because residence time of reacting gases traveling to sub-channel flow field is longer than to main channel.

• The Journal of Natural Sciences
• /
• v.9 no.1
• /
• pp.95-104
• /
• 1997

We synthesized the following series of 3', 5'hydroxy modified thymidine analogs to check the potential asymmetric catalytic effects. 3'-monomethylammino and dimethylaminothymidine was synthesized from thymidine via 8 step and 7 step in 38%, 20% overall yields respectively. 5'Acetyl-3'-dimethylamino thymidine was prepared from thymidine via 8 step in 40% overall yield. 5‘-TBS-3'-up-t BOC methylamino thymidine was prepared from thymidine via 6 step in 30% overall yield. 3'-acetyl-5'-t BOC amino thymidine was prepared from thymidine via 7 step in 31% overall yield.

• Journal of Life Science
• /
• v.16 no.1
• /
• pp.168-174
• /
• 2006

Enantiopure epoxides are valuable intermediates for the asymmetric synthesis of enantiopure bioactive compounds. Microbial epoxide hydrolases (EHs) are versatile biocatalysts for the preparation of enantiopure epoxides by enantioselective hydrolysis of cheap and easily available racemic epoxide substrates. EHs are commercially potential biocatalysts due to their characteristics such as high enantioselectivity, cofactor-independent catalysis, and easy-to-prepare catalysts. In this paper, recent progresses In molecular engineering of EHs are reviewed to evaluate the commercial feasibility of EH-catalyzed hydrolytic kinetic resolution for the production of enantiopure epoxides.

• Proceedings of the Korea Air Pollution Research Association Conference
• /
• 2000.11a
• /
• pp.274-275
• /
• 2000

현재 우리 나라는 공단지역에서 발생하는 VOCs(휘발성 유기화합물) 및 악취의 처리에 대한 연구개발 및 기존기술이 매우 취약한 실정이며, 일부 화학공장에서는 축열식 연소장치나 촉매연소장치를 설치하여 운전하고 있지만, 유지비(보조연료비)가 많이 소요되어 제대로 가동하지 못하는 경우가 있다. 대부분 제조업체의 경우, 활성탄 흡착탑을 설치하여 운영하지만, 화학공장에서 발생하는 포름알데히드, 스티렌 등과 같은 일부 물질은 흡착탑 내부에 타-르 같은 물질이 침적하고, 활성탄에 의한 흡착율이 낮다. (중략)

• Proceedings of the Korea Air Pollution Research Association Conference
• /
• 1999.10a
• /
• pp.447-448
• /
• 1999

현재 우리나라는 공단지역에서 발생하는 VOCs(휘발성 유기화합물) 및 악취의 처리에 대한 연구개발 및 기존기술이 매우 취약한 실정이며, 일부 화학공장에서는 축열식 연소장치나 촉매연소장치를 설치하여 운전하고 있지만, 유지비(보조연료비)가 많이 소요되어 제대로 가동하지 못하는 경우가 있다. 대부분 제조업체의 경우, 활성탄 흡착탑을 설치하여 운영하지만, 화학공장에서 발생하는 포름알데히드, 스티렌 등과 같은 일부 물질은 흡착탑 내부에 타-르 같은 물질이 침적하고, 활성탄에 의한 흡착율이 낮으며, 저농도에서도 악취가 발생하므로 이러한 저농도 VOCs 물질들의 처리에 Biofilter를 적용하여 처리가능성을 조사하였다.(중략)

• Journal of the Microelectronics and Packaging Society
• /
• v.6 no.2
• /
• pp.45-49
• /
• 1999

A flammable gas sensor based on the $SnO_2$thin film deposited by the reactive ion assisted deposition was fabricated and ultra-thin Pd layer as catalyst was adsorbed at surface by ion beam sputtering. The initial oxidation states of Pd catalyst were controlled to investigate the role of Pd in the sensing process of inflammale gas sensor through annealing in air and vacuum respectively. The Pd catalyst existing in pure metallic state showed the sensitivity higher than that of PdO. The result might be closely related to the fact that PdO as a surface acceptor would receive electrons via Pd sub-channel from $SnO_2$, and thus which reduces the sensitivity and delay the response time.