• Journal of Environmental Science International
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• v.11 no.9
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• pp.897-905
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• 2002

A three-dimensional photochemical air pollution model considered advection, dispersion, photochemical reactions, and precipitation processes was developed. The calculated results of meteorological observation clearly exhibited geographical effects of Gwangyang Bay, in which land and sea breezes, mount-valley winds and local circular winds occurred. The observed results of daytime NOx concentrations were slightly higher than the calculated NOx concentrations in Yosu industrial complex, Gwangyang iron mill, and container yard. Eventually, the calculated NOx results generally agreed well with the observed ones.

• Journal of Environmental Science International
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• v.16 no.8
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• pp.985-994
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• 2007

To investigate the effect of NOx and VOCs(volatile organic compounds) on the generation of high ozone episode, examined the hourly variations of ozone, NOx and VOCs concentrations, and calculated the ozone isopleth about maximum ozone concentrations using OZIPR which was presented by U. S. EPA at three sites in Busan. There was some difference by the sites, but decreasing VOCs concentration was effective for reduction of ozone at 22 July, the episode day of 2005. In the year 2006, the episode day was 8 August and the variations of NOx and VOCs concentration was little than variation of ozone. So it was estimated that the photochemical production of ozone was low than transportation of ozone. And the result of the OZIPR modeling was that decreasing VOCs concentration was effective for reduction of ozone.

• Journal of the Korean Institute of Gas
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• v.4 no.2 s.10
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• pp.1-6
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• 2000

In this experiment, we made the plasma reactor which adhere needle electrode in order to treat safely an NOx which was included in the gas. Also we experimently investigated characteristics of equipment and inspected efficiency. As a reaction gas, by using mixture gas of $NO/N_2$ and $N_2/O_2$, we setted up initial NO concentration and gas flow rate was set at 2 ${\iota}$/min. As a reaction characteristics of NOx, when discharge input power was high, NO concentration decreased and when the oxygen concentration increased, the NO decomposition was easy and decomposition energy efficiency was high. Also in case that NO concentration increased, NO decomposition energy efficiency was high but decomposition rate was low. The characteristics of ozone, when discharge input power was high, ozone increased and when $NO/N_2$ concentration increased, the ozone decreased.

• 한국연소학회:학술대회논문집
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• 2004.06a
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• pp.118-123
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• 2004

The combustion characteristics of 0.03MW turbulent methane/oxygen diffusion flames have been investigated to give basic informations for designing industrial oxyfuel combustors. NOx reduction has become one of the most determining factors in the combustor design since 3-5% nitrogen is intrinsically included from the current oxygen producing processes. Flame lengths and NOx concentrations were measured by varying flow velocities with and without installing quarls. Flame stabilities are significantly enhanced by oxyfuel combustion in contrast to air-fuel combustion. Flame length decreases with increasing fuel or oxygen velocity because of the enhancement of turbulent mixing. NOx concentration was reduced with increasing flo velocities. This can be attributed to the entrainment of inert product gases into flame decreasing flame temperature. The installation of quarl on the burners rather increased NOx concentration since the quarl blocked the entrainment above the nozzles.

• 한국전산유체공학회:학술대회논문집
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• 2010.05a
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• pp.368-375
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• 2010

To alleviate NOx emission, a variety of approaches has been applied. In marine diesels, the application of SCR systems has been considered an effective exhaust aftertreatment method for NOx emission control. Most current SCR systems use a various catalyst for the reaction of ammonia with NOx to form nitrogen and water. In theory, it is possible to achieve 100% NOx if the NH3-to-NOx ratio is 1:1. However, the reaction has a limited non-uniformity of the exhaust gas flow and ammonia concentration distribution. Therefore it is necessary to investigate the optimum flow conditions. In order to achieve uniform flow at monolith front face, we are equipped with a various mixed device. In this paper, it is presented that the mixed devices play an important role improvement of flow patterns and particle distributions of NH3 by numerical simulation.

• Journal of computational fluids engineering
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• v.15 no.4
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• pp.9-16
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• 2010

To alleviate NOx emission, a variety of approaches has been applied. In marine diesels, the application of SCR systems has been considered an effective exhaust aftertreatment method for NOx emission control. Most current SCR systems use a various catalyst for the reaction of ammonia with NOx to form nitrogen and water. In theory, it is possible to achieve 100% NOx if the $NH_3$-to-NOx ratio is 1:1. However, the reaction has a limited non-uniformity of the exhaust gas flow and ammonia concentration distribution. Therefore, it is necessary to investigate the optimum flow conditions. In order to achieve uniform flow at monolith front face, we are equipped with a various mixed devices. In this paper, it is presented that the mixed devices play an important role improvement of flow patterns and particle distributions of $NH_3$ by numerical simulation.

• Transactions of the Korean Society of Automotive Engineers
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• v.20 no.4
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• pp.150-155
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• 2012

Lean NOx Trap (LNT) catalysts are capable of reducing exhaust NOx emissions from diesel engines. LNT stores NOx in lean condition and exhausts N2 by reducing NOx in rich condition. NOx reduction characteristic of LNT catalysts using throttle position sensor and fuel injection timing control for light-duty diesel engine was investigated. In contrast to SCR system, LNT catalyst uses diesel fuel in resuctant. Also if the concentration of reductant is exceeded, excessive amount of reductant will slip throughout LNT and cause another emission problem. Thus LNT regeneration with precise engine control established that can make higher NOx conversion efficiency and lower fuel penalty, prevent another emission problem. NOx and reductant concentration were measured by the NOx sensor and Mexa7100D equipped inlet and outlet of catalyst. As a result of engine test, regeneration strategy has reached high of 77.8% NOx conversion efficiency according to engine operation condition. Moreover, we have proved that it is possible to use regeneration strategy of LNT within 5% fuel penalty.

• Resources Recycling
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• v.12 no.1
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• pp.41-47
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• 2003

In order to improve the hydration resistance of lime in the air at room temperature, carbonation and hydration experiments have been conducted. Carbonation of the surface of lime by about 6 wt％ was needed to suppress the hydration of lime used in steel-making. The effect of recirculation of rotary kiln exhaust gas for the carbonation of lime on the combustion temperature and NOx concentration was analyzed by thermodynamics. From the thermodynamic calculation results, it was frond that the equi-librium combustion temperature and NOx concentration decreased with increasing volume percentage of exhaust gas.

• Transactions of the Korean Society of Automotive Engineers
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• v.7 no.5
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• pp.73-80
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• 1999

To decrease NOx and SOx using PPCP(Pulse-induced Plasma Chemical Process). This study is tried to obtain the relation and the basic data under the various conditions such the initial concentrations of NOx and SOx. The additional amount of hydrocarbon gases. The concentration of oxygen and input power etc. Especially, this study is focused on the effects of the additional hydrocarbon gases on the decrease of NOx and SOx.

• Journal of Korean Society for Atmospheric Environment
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• v.9 no.3
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• pp.216-221
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• 1993

This study was carried out to determine the concentration of gaseous nitrate$(HNO_3)$ particulate nitrate$(NO_3^-)$ and conversion rate of NOx to nitrate in atmosphere in Seoul from Oct 1991 to July 1992. The average concentration of gaseous nitrate in daytime(09:00 - 17:00) was 9.93, 3.37, 7.40 and 10.40$\mug/m^3$ and, in highttime was 6.21, 7.31, 4.79 and 3.86$\mug/m^3$ respectively. The concentratin of $HNO_3$ was greater in summer and daytime than winter and nighttime. But the concentration of $NO_3^-$ was greater in winter and nighttime than in summer and daytime. The average conversion rate of NOx to $HNO_3$(Fn) indaytime was 13.18, 3.78, 9.13 and 23.13% and, in nighttime was 3.06, 1.37, 1.70 and 8.72% during fall, winter, spring and summer respectively. But the average conversion rate of NOx to $NO_3^-$(Fn') in daytime was 5.79, 5.77, 2.63 and 3.90% and in nighttime was 5.95, 6.51, 3.25 and 4.84% respectively. The average conversion rate of NOx to total nitrate $(HNO_3 + NO_3^-)$(Fn') was 12.72, 7.81, 7.82 and 18.40% respectively. The average conversion rate of NOx to $HNO_3$(Fn) was greater than $NO_3^-$(Fn') about 1.6 times.