• Journal of Power System Engineering
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• v.4 no.2
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• pp.31-39
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• 2000

Relationships between the plating condition and the plating rate of the deposition film for the electroless plating of Co-Cu-P alloy were discussed in this report. The result obtained from this experiment were summarized as follow ; The optimum bath composition was consisted of 0.8 ppm thiourea as a stabilizing agent. Composition of the deposit was found to be uniform after two hours of electroless plating. Plating rates of nickel-catalytic surface and zincate-catalytic surface were found to be very closely equal, but the plating time of nickel-catalytic surface took longer than that of the zincated-catalytic surface.

• Journal of Environmental Science International
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• v.11 no.6
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• pp.577-582
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• 2002

Selective catalytic reduction and selective non-catalytic reduction processes are mainly used to treat nitrogen oxidants generated from fossil-fuel combustion. Especially, the selective non-catalytic reduction process can be operated more economical and designed more simply than the selective catalytic reduction. For this reason, many researchers carried out to increase the removal efficiency of nitrogen oxidants in the condition of low oxygen concentration by using the selective non-catalytic reduction process. However, this study was flue gas contained high oxygen concentration of 20(v/v%) with ammonia as a reducing agent. Moreover, it carried out experiment with many factors that are reaction temperature, retention time, initial NO concentration, NSR(normalized stoichiometric ratio). It was determined optimal operating conditions to improve NO removal efficiency with SNCR process. The De-NOx efficiency was increased with NSR, initial NO concentration and retention time increasement. This study has NO removal efficiency over 80% in the high oxygen concentration as well as low oxygen concentration. The injection of reducing agent may be considered for SNCR process and facility operation in 850$\^{C}$ of optimal condition.

• Journal of Korean Society for Atmospheric Environment
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• v.13 no.4
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• pp.319-325
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• 1997

The catalytic decomposition of CFC-113(1,1,2-trichloro-1,2,2-trifluoroethane) was studied over an activated carbon catalyst in a fixed-bed reactor at the temperature from 300 to 600$^\circ$C, the space velocity (SV) of 1800 $\sim 14400h^{-1}$ and the mole ratio(decomposition agent/CFC-113) of 0.25 $\sim$ 5. In the absence of a decomposition agent, the decomposition efficiency of CFC-113 was low but when a decomposition agent was added to the gas stream, it was dramatically increased with the increase of temperature. In particular, in the presence of n-hexane as the decomposition agent it showed a high decomposition efficiency compared with benzene at 400$^\circ$C. It was found that the decomposition activity of CFC-113 was very sensitive to reaction temperature. Thus it is expected that to raise the reaction temperature is more effective than to increase the residence time and the amount of decomposition agent. Over the activated carbon catalyst more than 99% decomposition was achieved at the reaction temperature of 600$^\circ$C, SV of 7200$h^{-1}$, the mole ration $(C_6H_{14}/CFC-113)$ of 1 in this study.

• Journal of Microbiology and Biotechnology
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• v.31 no.1
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• pp.144-153
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• 2021

Organophosphorus nerve agents (OPNAs), including both G- and V-type nerve agents such as sarin, soman, tabun and VX, are extremely neurotoxic organophosphorus compounds. Catalytic bioscavengers capable of hydrolyzing OPNAs are under development because of the low protective effects and adverse side effects of chemical antidotes to OPNA poisoning. However, these bioscavengers have certain limitations for practical application, including low catalytic activity and narrow specificity. In this study, we generated a fusion-hybrid form of engineered recombinant human paraoxonase 1 (rePON1) and bacterial organophosphorus hydrolase (OPH), referred to as GV-hybrids, using a flexible linker to develop more promising catalytic bioscavengers against a broad range of OPNAs. These GV-hybrids were able to synergistically hydrolyze both G-type OPNA analogs (paraoxon: 1.7 ~ 193.7-fold, p-nitrophenyl diphenyl phosphate (PNPDPP): 2.3 ~ 33.0-fold and diisopropyl fluorophosphates (DFP): 1.4 ~ 22.8-fold) and V-type OPNA analogs (demeton-S-methyl (DSM): 1.9 ~ 34.6-fold and malathion: 1.1 ~ 4.2-fold above) better than their individual enzyme forms. Among the GV-hybrid clones, the GV7 clone showed remarkable improvements in the catalytic activity toward both G-type OPNA analogs (kcat/Km (106 M-1 min-1): 59.8 ± 0.06 (paraoxon), 5.2 ± 0.02 (PNPDPP) and 47.0 ± 6.0 (DFP)) and V-type OPNA analogs (kcat/Km (M-1 min-1): 504.3 ± 48.5 (DSM) and 1324.0 ± 47.5 (malathion)). In conclusion, we developed GV-hybrid forms of rePON1 and bacterial OPH mutants as effective and suitable catalytic bioscavengers to hydrolyze a broad range of OPNA analogs.

• 한국연소학회:학술대회논문집
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• 2006.04a
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• pp.79-85
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• 2006

In this study, to increase the mixing between flue gas and reducing agent, new shapes of $NH_3$ ejection nozzles are designed and experimentally and numerically tested. The nozzles have six holes perpendicular to the ambient flue gas flow and the tilting angle between direction of ambient flow and the hole axis is varied. To evaluate the mixing efficiency of the proposed nozzles, numerical and experimental tests are applied to several flow conditions comparing with single hole nozzle, which is commonly used in conventional SCR process. From the results the nozzle with tilted multi-holes has the large region of high turbulent intensity compared with conventional single hole nozzle. This is originated from the high vorticity near the upstream of the jet flow issuing from the hole. The high turbulent intensity and vorticity magnitude lead to enhanced mixing between flue gas and reducing agent. Hence, the most suitable moral ratio between NOx and reducing agent for the catalytic reaction can be obtained on behalf of the intensified scalar mixing within shorter physical mixing length.

• Applied Chemistry for Engineering
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• v.31 no.5
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• pp.581-584
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• 2020

The effect of a chemical pretreatment on the surface carbon was investigated using a scanning electron microscope (SEM) and electrochemical methods. Primitive carbon has a reducing power likely due to incompletely oxidized functional groups on the surface. We aim to control this reducing power by chemical treatment and apply for the spontaneous deposition of nanoparticles (NPs). Highly ordered pyrolytic graphite (HOPG) was initially treated with a reducing agent, NaBH4 or an oxidizing agent, KMnO₄, for 5 min. Subsequently, the pretreated carbon was immersed in a platinum (Pt) precursor. Unexpectedly, SEM images showed that the reducing agent increased spontaneous PtNPs deposition while the oxidizing agent decreased Pt loading more as compared to that of using bare carbon. However, the amount of Pt on the carbon obviously decreased by NaBH₄ treatment for 50 min. Secondly, spontaneous reduction on pretreated glassy carbon (GC) was investigated using the catalytic hydrogen evolution reaction (HER). GC electrode treated with NaBH4 for a short and long time showed small (onset potential: -640 mV vs. MSE) and large overpotential for the HER, respectively. Although the mechanism is unclear, the electrochemistry results correspond to the optical data. As a proof-of-concept, these results demonstrate that chemical treatments can be used to design the shapes and amounts of deposited catalytic metal on carbon by controlling the surface state.

• Korean Journal of Materials Research
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• v.12 no.2
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• pp.129-134
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• 2002

The optimum condition for fabricating cordierite disc type filter element was deduced. Cordierite monolith was used as starting material for filter element because it has many advantages such as high thermal shock resistance and good catalytic activity compared with $TiO_2$and SiC. The contents of organic additives and foaming agent were optimized to control the porosity and mechanical strength of cordierite filter. Among the required properties to be adopted as filter elements, the pressure drop and NOx removal efficiency were investigated depending on processing variables. It was found that pressure drop depends on particle size distribution of cordierite monolith and organic additives added as forming agent. The pressure drop at 5cm/sec of face velocity was in the range of 15~655mm$H_2O$ at room temperature. The NOx removal efficiency of catalytic filter with $V_2O_5$ as catalyst was over 85% at $450^{\circ}C$.

• Proceedings of the Korean Vacuum Society Conference
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• 2013.02a
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• pp.132-132
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• 2013

Colloidal synthesis of nanoparticles with well-controlled size, shape, and composition, together with development of in situ surface science characterization tools, such as ambient pressure X-ray photoelectron spectroscopy (APXPS), has brought new opportunities to unravel the surface structure of working catalysts. Recent studies suggest that surface oxides on transition metal nanoparticles play an important role in determining the catalytic activity of CO oxidation. In this talk, I will outline the recent studies on the influence of surface oxides on Rh, Pt, Ru and Co nanoparticles on the catalytic activity of CO oxidation [1-3]. Transition metal nanoparticle model catalysts were synthesized in the presence of poly(vinyl pyrrolidone) polymer capping agent and deposited onto a flat Si support as two-dimensional arrays using the Langmuir-Blodgett deposition technique. APXPS studies exhibited the reversible formation of surface oxides during oxidizing, reducing, and CO oxidation reaction [4]. General trend is that the smaller nanoparticles exhibit the thicker surface oxides, while the bigger ones have the thin oxide layers. Combined with the nature of surface oxides, this trend leads to the different size dependences of catalytic activity. Such in situ observations of metal nanoparticles are useful in identifying the active state of the catalysts during use and, hence, may allow for rational catalyst designs for practical applications. I will also show that the surface oxide can be engineered by using the simple surface treatment such as UV-ozone techniques, which results in changing the catalytic activity [5]. The results suggest an intriguing way to tune catalytic activity via engineering of the nanoscale surface oxide.

• Journal of environmental and Sanitary engineering
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• v.18 no.2
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• pp.27-33
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• 2003

This survey was performed to investigate the NOx emission factors at 3 Municipal Solid Waste Incinerators(MSWI) and 5 Power generation boilers in Seoul. The NOx concentrations were measured before and after control systems. The results were as follows. 1) The NOx reduction efficiencies of Selective Catalytic Reduction (SCR) using ammonia as reducing agent ranged from 53.7% to 89.9%. The NOx reduction efficiencies of SCR using methanol as reducing agent, Non- Selective Catalytic Reduction (NSCR) using ethanol as reducing agent and low-NOx burner were 20.8%, 29.1% and 24.7%, respectively. 2) The NOx emission factors at A-1, A-2 and A-3 facilities of MSWI were 0.786, 0.127 and 0.594 kg Nox/ton fuel, respectively. The factors of A-1 and A-3 facilities were higher than the average value of Korea. 3) The NOx emission factors at B-1, B-2, B-3, B-4 and B-5 facilities of Power generation boiler were 2.109, 0.726, 4.106, 8.378 and 5.168 kg Nox/ton fuel, respectively. The factors of B-4 and B-5 facilities were higher than the average value of Korea.

• Journal of the Korean Society of Industry Convergence
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• v.9 no.1
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• pp.13-19
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• 2006

The ozone produced by a dielectric barrier discharge device was injected into the exhaust gas to oxidize a part of NO to $NO_2$, and then the exhaust gas containing the mixture of NO and $NO_2$ was further treated in a catalytic reactor where both NO and $NO_2$ were reduced to $N_2$ in the presence of ammonia as the reducing agent. The $NO_2$ content in the mixture of NO and $NO_2$ was changed by the amount of ozone added to the exhaust gas. The experiments were primarily concerned with the effect of reaction temperature on the catalytic $NO_x$ reduction at various $NO_2$ contents. The increase in the $NO_2$ content by the ozone injection remarkably improved the performance of the catalytic $NO_x$ reduction, especially at low temperatures.