• Transactions of the Korean Society of Automotive Engineers
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• v.20 no.4
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• pp.142-149
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• 2012

The reduction characteristics of $NO_2$ to NO are experimentally studied over a platinum-based catalyst, especially at lower temperatures below about $200^{\circ}C$. In the present work, two types of steady-state experiments, engine bench and synthetic gas bench tests, are carried out in sequence. Steady-state engine bench tests with the DOC mounted on a light duty 4-cylinder 2.0 liter turbocharged diesel engine are performed and prove that CO plays a major role in $NO_2$ abatement at temperatures below the light-off temperature of CO oxidation, about $200^{\circ}C$. Synthetic gas bench tests are then performed using synthetic gas mixtures with CO, $C_3H_6$, NO, $NO_2$, $O_2$, $H_2O$ and $N_2$ in the $140{\sim}450^{\circ}C$ T-range and show that both CO and $C_3H_6$ are capable of reducing $NO_2$. It is noted that the reaction rate of $NO_2$ with $C_3H_6$ is much higher than that with CO. At temperatures below about $200^{\circ}C$, the reduction of $NO_2$ to NO is promoted with increasing CO concentration and $NO_2$/$NO_X$ ratio and with decreasing $O_2$ concentration, as well as with the presence of $H_2O$.

• Transactions of the Korean Society of Mechanical Engineers
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• v.17 no.6
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• pp.1556-1571
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• 1993

Nitrogen oxides ($NO_x$) are air pollutants which are generated from the combustion of fossil fuels. Stage combustion is an effective method to reduce $NO_x$ emissions. The effects of $NO_x$ reduction by stage combustion in a pilot scale combustor(6.6kW) have been investigated using propane gas flames laden with NH$_{3}$ as Fuel-N. The results in this study are follows; (1) $NO_x$ emissions are dependent on the reducing environment of fuel-rich zone regardless of total air ratio. The maximum $NO_x$ reduction is at the stoichiometric ratio of 0.8 to 0.9 in the reducing zone. (2) $NO_x$ reduction is maximum when burnout air is injected at the point where the oxygen in reducing zone is almost consumed. (3) $NO_x$ reduction is dependent upon the temperature of reducing zone with best effect above 950.deg. C in the reducing zone. (4) The fuel stage combustion is more effective to reduce $NO_x$ formation in the wide range of stoichiometric ratio than two stage combustion. (5) The results of this study could be utilized mainly in a design strategy for low $NO_x$ emission from the combustion of high fuel-nitrogen in energy sources ratio than as an indication of the absolute levels of $NO_x$ which can be achieved by stage combustion techniques in large scale facilities.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.35 no.5
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• pp.539-545
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• 2011

Combustion characteristics of industrial radiant tube (RT) burners with forced oscillating combustion technology are investigated using a real-scale (125,000 kcal/h) industrial RT burner facility in both laboratory and field tests. Three different types of industrial RT burners using a by-product gas from the iron-and-steelmaking process are examined in a laboratory facility equipped with a W-type RT. During the field tests, an industrial RT burner is characterized in a large facility equipped with multiple RTs. Their performance and emission controls are investigated under diverse operating conditions. The feasibility of the forced oscillating combustion technology is evaluated by the extent of $NO_x$ reduction and the efficiency improvement. These improvements are able to save energy, extend the RT lifetime, and enhance productivity. The operating conditions that achieve the best performance and emission control for each RT burner are determined.

• Proceedings of the Korea Society for Energy Engineering kosee Conference
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• 2002.11a
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• pp.39-44
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• 2002

배기가스의 규제가 전 세계적으로 강화되고 있는 가운데, 경유사용 디젤기관은 가솔린기관 보다 열효율이 높고 온실가스인 $CO_2$ 배출량이 적은 장점이 있으나, PM(입자상 물질)과 NO$_{x}$가 다량 배출되는 단점이 있다. 이들의 저감책으로서, 엔진개량, 연료분사장치의 고압화와 전자제어화, 배기 후처리기술의 적용 등 디젤기관의 고효율성을 손상시키지 않으면서, 배기공해를 대폭 저감하려는 연구가 활발히 추진되고 있으며, 한편으로는 디젤기관의 대체연료에 대한 연구가 활발히 추진되고 있다.(중략)

• Journal of the KSME
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• v.32 no.12
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• pp.1049-1058
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• 1992

자동차 공해를 저감하기 위해서는 정부 당국의 도로 여건 개선을 통한 교통 체증의 해소, 자동차 제조기술(연소, 제어, 배기가스 정화등)의 개선, 정유사의 저공해 연료 개발 및 운전자 개개인의 운전 습관 개선, 차량 정비 점검 등 제반 노력이 합치되어야 할 것이다. 이중 연료 측면에서의 대기오염 개선을 위한 저공해화 기술을 요약하면 다음과 같다. 자동차 배기가스에 영향을 미치는 휘발유의 황함량을 낮추면 휘발유 자동차의 유해 배기가스 배출이 전반적으로 감소한다. RVP와 방향족 함량은 낮을수록, 함산소화합물함량은 높을수록 HC와 CO를 저감시키며 특히 CO의 저 감이 현저하다. 90% 증류점을 낮추면 HC 배출량이 크게 감소하고 올레핀함량을 낮추면 $NO_{x$ 배출이 억제된다.

• Proceedings of the Korea Air Pollution Research Association Conference
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• 1999.10a
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• pp.211-212
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• 1999

오존경보제가 시행된 이후 오존경보의 발령 횟수 및 발령 지역이 점차 증가하고 있다. 이에 따라 각 지방자치단체에서는 대도시 광화학 스모그 생성의 중요한 원인물질 중 하나로 알려진 질소산화물의 배출을 저감시키기 위해 배출허용기준을 강화하려는 움직임을 보이고 있다. 발전소에서 운영하는 대형 보일러는 고온의 연소영역에서 운전이 이루어지므로 Thermal NOx의 생성이 지배적인 것으로 알려져 있다.(중략)

• Proceedings of the Korea Air Pollution Research Association Conference
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• 2008.10a
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• pp.275-276
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• 2008

• Proceedings of the Korea Air Pollution Research Association Conference
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• 2010.04a
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• pp.599-601
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• 2010

• Proceedings of the Korea Air Pollution Research Association Conference
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• 2009.10a
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• pp.428-429
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• 2009

• Korean Journal of Soil Science and Fertilizer
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• v.35 no.4
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• pp.216-222
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• 2002

Field experiments were conducted to investigate the effect of various cultural practices on methane($CH_4$) emission in tillage and no-tillage practice in a clayey paddy soil from 1998 to 2000. The factors evaluated in tillage and no-tillage methods were types of nitrogen fertilizers, application method of chemical fertilizers, rice straw application and cultivation method. Of the nitrogen fertilizers, the amount of $CH_4$ emission in ammonium sulfate plot was the lowest, regardless of tillage and the application method. 26.4~41.1% of reduction by ammonium sulfate compared with urea. But in no-tillage which have problem of poor rice yield than tillage, coated urea was more effective nitrogen fertilizer because that showed similar $CH_4$ emission and highest rice yield at 80% of dosage of nitrogen. No-tillage plot emitted lower $CH_4$ than tillage plot where the fertilizers were incorporated. On the contrary, no-tillage plot showed a little higher $CH_4$ emission compared with tillage plot for the surface application. When rice straw was applied, no-tillage practice reduced methane emission by 26.6% compared with tillage practice, but showing a little difference of 10.7% in no application. With cultivation method, no-tillage practice reduced methane emission 26.6% compared with tillage for the 30-d-old seedling transplanting. But for the dry direct seeding practice, no-tillage was a less effective because considerable amounts of rice straw incorporated by tillage were more decomposed aerobically in the soil and emitted as $CO_2$ to the atmosphere with flooding in no-tillage soil.