• Environmental Engineering Research
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• 제18권4호
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• pp.211-219
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• 2013

Rare-earth manganites have a great potential for environmental applications based on their chemical and physical properties. The use of rare-earth manganites as catalysts for environmentally essential reactions was reviewed. Artificial neural networks were used to assess the catalytic activity in oxidation reactions. Relative catalytic activities of the catalysts were further discussed. We concluded that cerium manganite is the most practicable catalyst for technological purposes.

• Elastomers and Composites
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• 제51권3호
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• pp.240-249
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• 2016

$BiVO_4$ nanomaterial was synthesized from bismuth (III) nitrate pentahydrate [$Bi(NO_3)_3{\cdot}5H_2O$] and ammonium vanadate (V) [$NH_4VO_3$]. The $BiVO_4$-graphene nanocomposite was fabricated by calcining the $BiVO_4$ nanomaterial and graphene under an oxygen-free atmosphere at $700^{\circ}C$. X-ray diffraction (XRD) and scanning electron microscopy (SEM) were employed to characterize structural and morphological properties of samples. The catalytic activity of the $BiVO_4$-graphene nanocomposite was studied for the reduction of 4-nitrophenol, 3-nitrophenol and 2-nitrophenol by sodium borohydride [$NaBH_4$]. The photocatalytic activity of the $BiVO_4$-graphene nanocomposite was demonstrated by the degradation of organic dyes like BG, MB, MO and RhB under irradiation at 365 nm. The catalytic and photocatalytic activity were studied by UV-vis spectrophotometry.

• 대한수의학회지
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• 제46권3호
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• pp.279-284
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• 2006

Photo-catalytic products have been widely used at home and hospital to prevent bacteria, virus and fungus. Activities of anti-bacteria, anti-viruses and anti-fungi are based upon direct contact of crystals and particles of titanium dioxide with pathogens, into which titanium is catalyzed by photo. Those antimicrobial activities of the photo-catalytic titanium dioxide have been proved in vitro. However, in vivo tests of those activities have not been carried out on dog skin. Aim of this study was to evaluate the antimicrobial activities of the catalytic titanium dioxide in vivo. Ten beagle dogs were divided into two groups. One group was sprayed with 10ml of titanium dioxide(1 mg/ml) whereas the other was not. The treated dogs were exposed under the sunlight for 120 min. A set of three hairs was taken 15, 30, 60 and 120 min after the exposure and the bacteria contaminated in hairs were amplified in, Muller Hilton broth at $35^{\circ}C{\pm}1$ for 3 h. The supernatant of the bacterial culture was diluted 1 : 10 in phosphafe-buffered saline. One milliliter of the diluents was transferred into triphenyltetrazolium medium(TTC) and incubated at $35^{\circ}C{\pm}1$ for 2 days. The number of bacteria was counted. The number of bacteria colonies was decreased compared to control group. To further investigate the longevity effect of titanium dioxide, the dogs were kept in indoor without sun light for 6 and 12 h, 1, 2, 3, 7, 14 days after exposure of the chemical during each 15, 30, 60 min. The number of bacteria colony in 1ml was counted. The number of bacterial colonies was decreased. Treated group is exposured by sun light during 15 min, the longevity effect of titanium dioxide is continued by 1 week. Treated group is exposured by sun light during 30, 60 min, the longevity effect of titanium dioxide is continued over 2 weeks. These data indicated that the photo-catalytic titanium dioxide may be used for prevent bacteria on dog skin.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2011년도 제41회 하계 정기 학술대회 초록집
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• pp.213-213
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• 2011

Gold catalysts supported on TiO2 have shown a unique catalytic behavior on CO oxidation, depending on surface effects. Particle size has an influence on the surface activity. To make monodisperse Au nanoparticles, organic capping ligands, such as alkylthiols, were used by a "greener" synthesis method [1,2] and Au nanoparticles were deposited on TiO2. However, organic capping ligands must be removed for high catalytic activities by the Au nanoparticles without changing the Au size [3]. We used UV ozone treatment to decompose thiol ligands. The samples have been characterized by X-ray photoelectron spectroscopy to examine the surface modification by UV ozone treatment. We show the size distribution of the gold nanoparticles by light scattering analysis and transmission electron microscopy. Au/TiO2 have been prepared using the wetness impregnation method. The catalytic performance of CO oxidation over Au supported on TiO2 under oxidizing reaction conditions (40 Torr CO and 100 Torr O2) were tested. The results show that the catalytic activity depends on particle size and the time of UV ozone exposure, which suggests the role of sulfur bonding in determining the catalytic activity of Au/TiO2 catalysts.

• 공업화학
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• 제2권1호
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• pp.77-85
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• 1991

염산 및 불산으로 모더나이트를 처리하여 실리카/알루미나 비가 다른 일련의 시료를 만들었다. 이러한 시료에 대하여 암모니아 TPD와 피리딘 흡착으로 IR을 이용하여 산성도를 측정하고 o-xylene 반응의 활성과 이성화반응에 대한 선택성을 측정하였다. 그 결과 염산처리 시료는 실리카/알루미나 비가 증가할수록 구조알루미늄이 추출되어 산량이 감소하였으며 실리카/알루미나 비가 22인 시료가 다른 시료들보다 활성이 좋았다. 불산처리 시료는 불산처리 시 불소가 구조 중 규소원자와 결합하였으며 처리시간이 증가함에 따라 결합된 불소는 증가하였다. 이 경우의 활성은 염산처리와는 달리 알루미늄의 추출과 함께 모더나이트의 수산기가 불소로 치환되어 이로 인하여 산점이 줄어 활성이 감소하나 불산은 규소도 추출하므로 표면을 파고들어 새로운 면이 노출되어 산점이 형성되고 이 산점은 증가된 결합불소의 영향을 받아 강해지면서 활성이 다소 증가하였다.

• 약학회지
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• 제49권3호
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• pp.198-204
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• 2005

Human foamy virus (HFV) integrase mediates integration of viral c-DNA into cellular DNA. In this process, HFV integrase recognizes its own viral DNA specifically and catalyzes insertion of viral c-DNA. In order to study catalytic domains and residues, three deletion mutants and two point mutants of HFV integrase were constructed and analyzed with respect to enzymatic activities. The C-terminal deletion mutant showed decreased enzymatic activities while the N-terminal deletion mutant lost the activities completely, indicating that the N-terminal domain is more important than the C-terminal domain in enzymatic reaction. The point mutants, in which an aspartic acid at the 164th position or a glutamic acid at the 200th position of the HFV integrase protein was changed to an alanine, lost the enzymatic activities completely. However, they were well complemented with other defective deletion mutants to recover enzymatic activities partially. Therefore, these results suggest that the aspartic acid and glutamic acid at the respective 164th and 200th positions are catalytic residues for enzymatic reaction.

• 한국연소학회:학술대회논문집
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• 한국연소학회 2001년도 제22회 KOSCI SYMPOSIUM 논문집
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• pp.46-52
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• 2001

In this study, the generation of oxygen-free gas using catalytic combustion for industrial applications is explained ; heat treatment and copper annealing. For the experiment, Pd catalysts were determined by testing their catalytic activities over LPG in a micro-reactor. Combustion characteristics for the generation of oxygen-free atmospheric gas and the effect of flue gas upon surface oxidation were estimated form this experiment. As a result of the experimental investigation, we can state that the catalytic combustion could generate oxygen-free atmospheric gas suitable for industrial applications, but vapor produced by combustion process must be carefully considered as a new factor of surface oxidation.

• 한국생물공학회:학술대회논문집
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• 한국생물공학회 2000년도 추계학술발표대회 및 bio-venture fair
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• pp.571-574
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• 2000

Hydrolase는 생물학적 공정에서 가장 널리 사용되는 효소군 중의 하나이다. 본 연구에서는 hydrolase들 중에 xylanase, lysozyme, glucoamylase, barnase가 대상 hydrolase로 선택하여 최적 pH를 예측하는 방법론을 제시하였다. Tanford-Kirkwood(TK) model에 기반을 두고 선택된 효소들의 catalytic residue들의 전하 변화가 optimum pH에 중요한 인자로서 그 catalytic residue들의 전하 차이가 최대일 때의 pH가 optimum pH로 나타났다. 이렇게 예측된 optimum pH 결과들은 실험적으로 결정된 optimum pH와 서로 잘 일치하고 있음을 보여준다.

• 한국환경과학회지
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• 제22권8호
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• pp.1019-1027
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• 2013

Sulfur hexa-fluoride has been used as a etching gas in semiconductor industry. From the globally environmental issues, it is urgent to control the emissions of this significant greenhouse gas. The main objective of this experimental investigation was to find the effective catalyst for $SF_6$ decomposition. The precursor catalyst of hexa-aluminate was prepared to investigate the catalytic activity and stability. The precursor catalyst of hexa-aluminate was modified with Ni to enhance the catalytic activities and stability. The catalytic activity for $SF_6$ decomposition increased by the addition of Ni and maximized at 6wt% addition of Ni. The addition of 6wt% Ni in precursor catalyst of hexa-aluminate improved the resistant to the HF and reduced the crystallization and phase transition of catalyst.

• 한국전기화학회:학술대회논문집
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• 한국전기화학회 1998년도 제1회 총회 및 추계학술발표회
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• pp.30-30
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• 1998