• Transactions of the Korean hydrogen and new energy society
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• 제21권6호
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• pp.519-525
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• 2010

Ethanol was used as reductant to remove $NO_x$ over Ag/$Al_2O_3$ catalyst via SCR from stationary emission source. Among the tested hydrocarbon reductants, ethanol showed highest de-$NO_x$ performance over the Ag/$Al_2O_3$ catalyst. De-$NO_x$ efficiency of about 83% was obtained in the condition of GHSV 20,000 $hr^{-1}$, $NO_x$ 200 ppm, CO 200 ppm, $O_2$ 13%, $H_2O$ 5% and mole ratio of ethanol/$NO_x$ = 2 between temperature of $300^{\circ}C$ and $400^{\circ}C$. While $SO_2$ presence in the $NO_x$ exhaust suppressed the catalytic activity, catalyst with acid (0.7% $H_2SO_4$) treatment of catalyst showed higher catalytic activity, where In-Situ DRIFT showed S presence over catalyst surface was increased after acid treatment of catalyst. From in-situ DRIFT and SCR results, it was concluded that sulfur presence over the surface of Ag/$Al_2O_3$ catalyst was the dominant factor to control the de-$NO_x$ reaction yield via HC-SCR from the exhausted gas including $SO_2$.

• Korean Journal of Materials Research
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• 제26권5호
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• pp.250-257
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• 2016

Octahedral $Co_3O_4$/carbon nanofiber (CNF) composites are fabricated using electrospinning and hydrothermal methods. Their morphological characteristics, chemical bonding states, and electrochemical properties are used to demonstrate the improved photovoltaic properties of the samples. Octahedral $Co_3O_4$ grown on CNFs is based on metallic Co nanoparticles acting as seeds in the CNFs, which seeds are directly related to the high performance of DSSCs. The octahedral $Co_3O_4$/CNFs composites exhibit high photocurrent density ($12.73mA/m^2$), superb fill factor (62.1 %), and excellent power conversion efficiency (5.61 %) compared to those characteristics of commercial $Co_3O_4$, conventional CNFs, and metallic Co-seed/CNFs. These results can be described as stemmnig from the synergistic effect of the porous and graphitized matrix formed by catalytic graphitization using the metal cobalt catalyst on CNFs, which leads to an increase in the catalytic activity for the reduction of triiodide ions. Therefore, octahedral $Co_3O_4$/CNFs composites can be used as a counter electrode for Pt-free dye-sensitized solar cells.

• Journal of the Korea Academia-Industrial cooperation Society
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• 제10권10호
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• pp.2779-2785
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• 2009

Among the livestock, chickens are raised because of the merit ingested protein in low-priced cost of production and are primary livestock increased the consumption of meat. The factors of influencing condition, odor is the most important factor. Odor substances are ammonia, amines, hydrogen sulfide and mercaptan which come from night soil. Livestock are prevented from rearing by means of these odor substances. Though the henhouse is heated using hot air type heater in the winter season, it is ventilated for the control of odor because of the increase of odor concentration. In the present work, composite catalytic system combined the existing facilities(hot air type heater) with catalytic system was developed, it could controled odor and hazardous gas using the oxidation/reduction reaction without extra operating cost. Moreover, the purpose of this work is to develop the catalysts which are cost competitive and can maximize energy efficiency. The catalysts are noble metal(Pt-Rh) and composite transition metal(Mn) type.

• Journal of the Korean Institute of Gas
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• 제2권1호
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• pp.1-6
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• 1998

A low power (below than 300 mW) catalytic bead combusible gas sensor is developed and utilized with a computer controlled sampling system for measuring heat content of natural gas. The heat content of gas is proportional to the change in the energy required to exposure to the sample of combustible gas. The heat content of natural gas samples ranging 36.30 - 39.88 $MJ/m^3$ is measured in the range of approximately $1\%$ error, which is comparable to its nominal heat content. Each gas represents a slightly different curve of sensitivity to sensor temperature. Thus all of the sensitivities are not equal to every temperature. In calibration process the choice of a optimum operating temperature is an important factor that influences the overall performance of the measurement system.

• Journal of Life Science
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• 제17권4호
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• pp.581-586
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• 2007

Staphylococcus epidermidis is a coagulase-negative, gram-positive bacterium that normally inhabits the human skin. S. epidermidis is also known to be an opportunistic pathogen in infections of various indwelling medical devices. This report describes purification and characterization of the urease of S. epidermidis urease, which may act as a virulence factor. The urease from S. epidermidis was purified 1,127 fold by using DEAE-Sepharose, Phenyl-Sepharose, Mono-Q and Superdex HR200 column chromatography. The specific activity of the purified enzyme was 993.8 U/mg. Michaelis constant($K_m$) of the enzyme was estimated to be 8.5 mM urea by using Lineweaver-Burke double reciprocal plot. The native molecular weight of the urease was shown to be 255 kD by using Superose 6HR gel filtration chromatography and the purified enzyme contained 2.2 nickel ions per catalytic unit. The overall stoichiometry of the enzyme subunits appears to be $(\alpha\beta\gamma)_3$, which is consistent with the enzymes from other bacteria sources.

• Korean Chemical Engineering Research
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• 제45권6호
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• pp.663-668
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• 2007

The autothermal reforming reaction of methane was investigated to produce hydrogen with $Ni/CeO_2-ZrO_2$ catalysts. Alumina-coated honeycomb monolith was applied in order to obtain high catalytic activity and stability in autothermal reforming of methane. Metallic monolithic catalyst showed better methane conversion than that of powder type at high reaction temperature. It was confirmed that $H_2O/CH_4/O_2$ ratio was important factor in autothermal reforming reaction. $H_2$ yield was increased as $H_2O/CH_4$ ratio increased. Methane conversion was improved as $O_2/CH_4$ ratio was increased, whereas, the yield of $H_2$ was decreased. The catalytic activity for $Ni/CeO_2-ZrO_2$ catalyst with 0.5 wt% Ru loading was improved at low reaction temperature.

• Archives of Pharmacal Research
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• 제4권2호
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• pp.109-115
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• 1981

In the present investigation, an attempt has been made to apply the methods of classical chemical kinetics to the hydrolytic reaction of pipethanate hydrochloride. By successively keeping all but one variable essentially constant, it has been possible to resolve the overall effect of the individual contributing factors. Since nearly all commercial pipethanate preparations are formulated with antacid, studies were made at several constant hydrogen ion concentration ranging pH 0.4 to 7.5. Rate measurement was also carried out in temperature ranging from $25^{\circ}C$ to $60^{\circ}C$. The hydrolysis of pipethanate is found to be of first order with respect to pipeethanate concentration over an experimental range of hydrogen ion concentration (pH 0407.5). The apparent activation energy(Ea) at pH 7.5 is 18.30 Kcal/mole and the frequency factor is $1.1408 {\times}10^{9}sec^{-1}$. The rate of the hydrolysis has a minimum at pH 2.5-3.5. In this region the half-life of pipethanate was about15.3 days at $60^{\circ}C$. The catalytic effect of water was found to be $K_{H_2O}$ = $3.16{\times}10^{-5}min^{-1}$ at $60^{\circ}C$. The catalytic constants of the hydroxyl ions and hydrogen ions at $60^{\circ}C$ were also found to be $K_{OH}$ = $4.5519{\times}10^{-5}min^{-1}$ and $K_{H}+$ = $1.1568{\times}10^{-2}min^{-1}$, respectively. This reaction appears to be primarily base catalyzed hydrolysis and pipethanate is relatively reluctant toward acid catalyzed hydrolysis. A positive primary salt effect was noted in the solution of phpethanate at pH 7.5 and at $60^{\circ}C$.

• Applied Chemistry for Engineering
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• 제33권6호
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• pp.594-599
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• 2022

In the study, NH₃-SCO (selective catalytic oxidation) reaction activity accodrding to vanadium loading amount were compared when preparing Pt/V/TiO₂. Considering both NH₃ conversion rate and N₂ selectivity, V 2 wt% loading of the catalyst showed the best activity. When the correlation between physical/chemical characteristics and reaction activity was confirmed, it was confirmed that the increase in lattice oxygen and (V³⁺ + V⁴⁺) ratios were active factor. In addition, when the SO₂ durability experiment was conducted using the best catalyst, it was confirmed that the influence was insignificant even if the high concentration of SO₂ was injected.

• BMB Reports
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• 제50권11호
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• pp.537-538
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• 2017

Hypoxia affects various physiological and pathophyological processes. Hypoxia changes the expression of hypoxia-responsive genes through two main pathways. First, hypoxia activates transcription factors (TF) such as Hypoxia-inducible Factor (HIF). Second, hypoxia decreases the activity of Jumonji C domain-containing histone demethylases (JMJDs) that require $O_2$ and ${\alpha}$-Ketoglutarate (${\alpha}$-KG) as substrates. The JMJDs affect gene expression through their regulation of active or repressive histone methylations. Profiling of H3K4me3, H3K9me3, and H3K27me3 under both normoxia and hypoxia identified 75 TFs whose binding motifs were significantly enriched in the methylated regions of the genes. TFs showing similar binding strengths to their target genes might be under the 'metabolic control' which changes histone methylation and gene expression by instant changing catalytic activities of resident histone demethylases.

• 한국가스학회:학술대회논문집
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• 한국가스학회 1997년도 추계학술발표회 논문집
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• pp.229-235
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• 1997

A low power (300 mW) catalytic bead combustible gas sensor is developed and utilized with a computer controlled sampling system for measuring heat content of natural gas. The heat content of gas is proportional to the change in the energy required to exposure to the sample of combustible gas. The heat content of natural gas samples ranging 36.30 - 39.88 MJ/$m^3$ is measured in the range of approximately $1\%$ error, which is comparable to its nominal heat content. Each gas has a slightly different curve of sensitivity vs. sensor temperature. Thus there Is no temperature at which all sensitivities are equal. In calibration process the choice of a optimum operating temperature is an important factor that influences the overall performance of the measurement system.