• Journal of Korean Society for Atmospheric Environment
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• v.32 no.1
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• pp.9-20
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• 2016

Ozone has been a problem in big cities. That is secondary air pollutant produced by nitrogen oxide and VOCs in the atmosphere. In order to solve this, the first to be the analysis of the $NO_x$ and VOCs. The main source of nitrogen oxide is the road mobile. Industrial sources in Seoul are particularly low, and mobile traffics on roads are large, so 45% of total $NO_x$ are estimated that road mobile emissions in Seoul. Thus, it is necessary to clarify the relation with the activity of road mobile source and $NO_x$ concentration. In this study, we analyzed the 4 locations with roadside automatic monitoring systems in their center. The V.K.T. calculating areas are set in circles with 50 meter spacing, 50 meter to 500 meter from their center. We assumed the total V.K.T. in the set radius affect the $NO_x$ concentration in the center. We used the hourly $NO_x$ concentrations data for the 4 observation points in July for the interference of the other sources are minimized. We used the intersection traffic survey data of all direction for construction of the V.K.T. data, the mobile activities on the roads. ArcGIS application was used for calculating the length of roads in the set radius. The V.K.T. data are multiplied by segment traffic volume and length of roads. As a result, the $NO_x$ concentration can be expressed as linear function formula for V.K.T. with high predictive power. Moreover we separated background concentration and concentrations due to road mobile source. These results can be used for forecasting the effect of traffic demand management plan.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.31 no.7
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• pp.521-526
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• 2018

In particular, gas sensors require characteristics such as high speed, sensitivity, and selectivity. In this study, we fabricated a $NO_X$ gas sensor by using a multi-walled carbon nanotube (MWCNT)/zinc oxide (ZnO) composite film. The fabricated MWCNT/ZnO gas sensor was then treated by a $450^{\circ}C$ temperature process to increase its detection sensitivity for NOx gas. We compared the detection characteristics of a ZnO film gas sensor, MWCNT film gas sensor, and the MWCNT/ZnO composited film gas sensor with and without the heat-treatment process. The fabricated gas sensors were used to detect $NO_X$ gas at different concentrations. The gas sensor absorbed $NO_X$ gas molecules, exhibiting increased sensitivity. The sensitivity of the gas sensor was increased by increasing the gas concentration. Additionally, while changing the temperature inside the chamber for the MWCNT/ZnO composite film gas sensor, we obtained its sensitivity for detecting $NO_X$ gas. Compared with ZnO, the MWCNT film gas sensor is excellent for detecting $NO_X$ gas. From the experimental results, we confirmed the enhanced gas sensor sensing mechanism. The increased effect by electronic interaction between the MWCNT and ZnO films contributes to the improved sensor performance.

• Korean Chemical Engineering Research
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• v.49 no.6
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• pp.739-744
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• 2011

Activated carbon SCR(CSCR) catalyst that is used to remove $NO_x$ in exhaust gas including boron discharged from the production process of liquid crystal display(LCD) shows deactivation when boron is deposited to block the pores within the catalyst or to cover its active sites. The spent carbon catalyst is regenerated by washing with various surfactants, drying and calcination. For comparison of the physical and chemical properties before and after the regeneration with the variables, type of surfactants and calcination condition, element analysis by ICP, $N_{2}$ adsorption were conducted. $DeNO_{x}$ in SCR with $NH_3$ was carried out in a fixed bed reactor at $120^{\circ}C$. The activated carbon catalyst regenerated through washing with a non-ionic surfactant in $H_{2}O$ at $90^{\circ}C$ and calcination under $N_{2}$ gas at $550^{\circ}C$ shows similar level of surface area and $NO_x$ removal efficiency with those of fresh catalyst.

• Korean Journal of Construction Engineering and Management
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• v.25 no.5
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• pp.73-81
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• 2024

In South Korea, NO_X emissions are a major concern, leading to acid rain and smog, harming both the atmosphere and human health, particularly in urban areas. This study seeks to determine the most advantageous pavement material for NO_X reduction in urban areas and assess whether photocatalytic pavement blocks, proven to reduce NO_X emissions, can serve as a viable alternative to conventional cement pavement blocks. To achieve this, a comparative life cycle cost (LCC) analysis was conducted between photocatalytic pavement blocks and conventional cement pavement blocks installed for their NO_X reduction capabilities. The cost-saving benefits of NO_X reduction were monetized for photocatalytic pavement blocks. The analysis period was based on the least common multiple of the replacement cycles of both pavement materials: 30 years. The results revealed that while photocatalytic pavement blocks initially produce higher installation costs than cement pavement blocks, they offer greater cost savings in terms of total cost and net present value due to their NO_X reduction effect over the life cycle. Additionally, the cost-saving effects of photocatalytic pavement blocks are even more pronounced because their replacement period is 5 years longer than that of cement pavement blocks. This study holds significance in performing an LCC analysis of the previously unanalyzed photocatalytic pavement blocks while also demonstrating their potential as substitutes for cement pavement blocks.

• Journal of Korean Society for Atmospheric Environment
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• v.14 no.1
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• pp.25-33
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• 1998

We have studied the reduction of NO by propane over perovskite-type oxides prepared by malic acid method. The catalysts were modified to enhance the activity by substitution by substitution of metal into A or B site of perovskite oxides. In addition, the reaction conditions, such as temperature, $O_2$ concentration, space velocity have been studed. In the $LaCoO_3$ type catalyst, the partial substitution of Ba, Sr into A site enhanced the catalytic activity in the reduction of NO. In the $La_{0.6}Sr_{0.4}Co_{1-x}Fe_xO_3(x=0 \sim 1.9)$ catalyst, the partial substitution of Fe into B site enhanced the conversion of NO, but excess amount of Fe decreased the conversion of NO. The surface area and catalytic activity of perovskite catalysts prepared by malic acid method showed higher values than those of solid reaction method. In the $La_{0.6}Sr_{0.4}Co_{1-x}Fe_xO_3$ catalyst, the conversion of NO increased with increasing $O_2$ concentration and contact time. The introduction of water into reactant feed decreased the catalytic activity.

• 한국연소학회:학술대회논문집
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• 2007.05a
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• pp.54-59
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• 2007

In a view of capturing $CO_2$ as a greenhouse gas, an experimental study was conducted on the combustion characteristics of pulverized coal in $O_2$/$CO_2$ environment using TGA/DSC and DTF facilities. The effects of gas composition and concentration on the processes of devolatilization and char burning experienced by coal particles in combustion furnace and on the concentration of products such as $CO_2$, CO and $NO_x$ were observed using TGA/DSC and DTF respectively. As results, it were found that the rate of devolitilation is nearly independent on the $O_2$ concentration if it is over 20% but the char burning rate is a sensitive function of $O_2$ percent, and the two rates can be controlled by $O_2$ concentration in order to be similar with those of air combustion case. It was also found that high concentration $CO_2$ can be captured by oxy-coal combustion and high concentration of CO and low value of $NO_x$ are exhausted in that case. Additionally, NO reducing reaction by CO with char as catalyst was observed and a meaningful results were obtained.

• Clean Technology
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• v.2 no.1
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• pp.22-31
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• 1996

• Korean Chemical Engineering Research
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• v.51 no.2
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• pp.163-170
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• 2013

Selective catalytic reduction of $NO_x$ by $NH_3$ ($NH_3$-SCR) over $V_2O_5/TiO_2$-based catalysts is recently reported to be an anthropogenic emitter of $N_2O$ that is a global warming gas with a global warming potential of 310. Therefore, this review will get a touch on significance of some parameters regarding $N_2O$ formation in the $deNO_xing$ reaction for fossil fuels-fired power plants applications. The $N_2O$ production in $NH_3$-SCR reaction with such catalysts occurs via side reactions between $NO_x$ and $NH_3$ in addition to $NH_3$ oxidation, and the extent of these undesired reactions depends strongly on the loadings of $V_2O_5$ as a primary active component and the promoter as a secondary one ($WO_3$ and $MoO_3$) in the SCR catalysts, the feed and operating variables such as reaction temperature, $NO_2/NO_x$ ratio, oxygen concentration, gas hourly space velocity, water content and thermal excursion, and the physical and chemical histories of the catalysts on site. Although all these parameters are associated with the $N_2O$ formation in $deNO_xing$ reaction, details of some of them have been discussed and a better way of suppressing the $N_2O$ production in commercial SCR plants has been proposed.

• Journal of Korean Society for Atmospheric Environment
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• v.26 no.1
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• pp.1-9
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• 2010

In this study, the selective catalytic reduction of $NO_x$ with ammonia was carried out in a filter bag support reactor. The experiments were performed by powder type $MnO_x$ and $V_2O_5$/$TiO_2$ catalyst at low temperature between 130 and $250^{\circ}C$. Also, the effect of $SO_2$ and $H_2O$ on the NO conversion was investigated under our test conditions. The powder type catalysts were analyzed by X-ray photoelectron spectrum (XPS), X-ray diffraction(XRD), scanning electron microscopy (SEM) and thermal gravimetric analysis (TGA). It was observed that NO removal efficiency of the powder type $V_2O_5$/$TiO_2$ catalyst was 85% at low temperature($200^{\circ}C$) under presence of oxygen and that of $MnO_x$ was 50% at the same condition. The powder type $V_2O_5$/$TiO_2$ catalyst, in conclusion, was found to be available for SCR reaction in a filter bag support system.

• Journal of Powder Materials
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• v.5 no.4
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• pp.273-278
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• 1998

$De-NO_x$ transition metals(Cu, Co)/ZSM-5 catalyst was made by mechanical alloying method, and their microstructures and repeated usage-properties were investigated by scanning electron microscopy, transmission electron microscopy and X-ray diffraction. The conversions ability of NO in the catalyst was measured. A part of ZSM-5 in CO/ZSM-5 composite powders was amorphous and the amorphous phase became less stable with increasing Co content. Conversion ability of NO in 10Cu/ZSM-5 powders decreased from 89% to 12% and that in 10Co/ZSM-5 decreased from 22% to 17% by 7 times conversion tests.