• 한국수소및신에너지학회논문집
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• 제23권6호
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• pp.634-639
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• 2012

The contribution levels of emissions from the heavy-duty vehicles have been continuously increased. Among the exhaust emissions, NOx (nitric oxides) have a ratio of 73.2% and particle matters have a proportion of 61.8% in the heavy-duty vehicles. Also, natural gas vehicles have the 78.9% of total registered local buses in Korea. Therefore, the investigation on emission characteristics of heavy-duty vehicles using CNG and diesel fuel according to the various driving cycles was carried out in this study. In order to analyze the emission characteristics, the five kinds of buses by using CNG and diesel fuels with a after-treatment devices (DPF, p-DPF) was used and five test driving schedules were applied for analysis of emission characteristics in a chassis dynamometer. To analyze the exhaust emission, the exhaust emission and PM analyzers were used. From this study, it is revealed that diesel buses with after-treatment had reduced emission of CO, HC, PM but NOx. Also, NMHC emission of CNG bus have a higher level and NOx level was similar with diesel buses. In addition, emissions in NIER06 with slow average speed shows lowest levels compared to other test modes.

• 한국분무공학회지
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• 제23권4호
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• pp.175-184
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• 2018

Emission characteristics of regulated (NOx, PM, CO, NMHC) and unregulated (VOCs, aldehydes, PAHs) air pollutants were investigated for diesel heavy duty buses equipped with different after-treatment systems (DPF+EGR and SCR) under urban driving cycle. The combustion temperature and the working temperature of SCR catalysts were important to make impact on NOx emissions, whereas PM emissions were low. The alkane groups dominated NMVOCs emissions, making 42.6~59.4% of sum of the NMVOCs emissions. Especially, alkane emissions of DPF+EGR-equipped vehicle included DOC had 14.9~15.5% higher than those of SCR-equipped vehicle due to low efficiency of oxidation catalyst. In the case of individual NMVOCs, n-nonane and propylene emissions highly occupied for DPF+EGR and SCR, respectively. Formaldehyde emissions among aldehydes were the highest and PAHs emissions were hardly detected except naphthalene and phenanthrene. The NMHC speciation has been shown to be the highest of the formaldehyde ranged 20.8~21.5%. The results of this study will be contributed to establish Korean HAPs emission inventory for automobile source.

• 한국가스학회지
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• 제15권1호
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• pp.9-14
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• 2011

대형 디젤엔진은 주행거리가 길고 배기량이 크기 때문에 차량의 대수는 상대적으로 적지만 대기환경에 미치는 영향은 크다. 시내를 주행하는 시내버스의 경우 한일 월드컵을 계기로 CNG 버스로 전환되었다. 그러나 대형트럭과 장거리 시외버스의 경우 주행거리가 길고 CNG 충전소가 대도시의 시내버스 차고지 위주로 설치되어 있어 이용이 불가능하였다. 단열용기의 적용으로 천연가스를 압축상태가 아닌 액체 상태로 보관이 가능해져 주행거리가 긴 대형트럭이나 장거리 시외버스로의 적용이 가능해졌으며, 혼소엔진의 경우 LNG 충전이 어려운 지역에서는 디젤로 운행이 가능하다. 이와 같은 장점으로 인하여 석유 의존도를 크게 낮출 수 있어 에너지원의 다변화가 가능하며, 디젤차의 고질적인 단점으로 여겨왔던 매연 및 질소산화물뿐만 아니라 저탄소 연료를 사용함으로서 대표적인 온실가스중의 하나인 이산화탄소도 10%이상 저감할 수 있었다.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2007년도 춘계학술대회B
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• pp.3335-3340
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• 2007

The government have been tightening EM regulation gradually but the effect is not good because of rapid increase of vehicles. And medium & heavy duty diesel vehicles, even though the number is small, exhaust very large pollutants(about over 50%). Especially it is more severe about old trucks and buses. Accordingly, CNG vehicle and the retrofit of diesel to CNG must be an alternative in order to protect the atmospheric environment and improve the air quality in the metropolitan area. The main object of this study is to secure the retrofit technology of diesel to CNG vehicle and the management system of CNG engine. we passed the government emission certification test. In addition to this, the mass production for retrofit is also studied. Results of emission and durability test for certification are as follows; there was no problem during 30,000km vehicle durability test and good emission levels satisfying the regulation.

• 산업기술연구
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• 제26권B호
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• pp.11-20
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• 2006

LNG is a valuable fuel since it offers some environmental, energy security and economic benefits over diesel. It could be used mainly in heavy-duty trucks and buses. Car acceleration induces the slope angle of the liquid fuel in the tank. Slope angle changes the surface area wetted by liquid fuel and consequently heat leak to the tank. This research is a result of numerical simulation of the heat leak with the car acceleration to LNG tank. The "Pro-HeatLeak" Fortran program is developed and the verification test of the developed program is done. The difference between numerical results and calculated results from MathCad verification test is less than 0.07 percent. The smallest heat leak is correspond to the case without oscillation. For the high car acceleration the value of heat leak is greater than that for the small acceleration. The difference between maximum and minimum heat leak for 10 gallons of fuel vapor in the tank is about 10 percent.

• 한국대기환경학회지
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• 제24권1호
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• pp.72-82
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• 2008

Benzene is a very harmful and toxic compound known as human carcinogen by all routes of exposure. Owing to the risky feature of benzene, several countries such as Japan, UK and EU have established the ambient air quality standard and protect from that risk of it. Korea also has designated it as one of the criteria air pollutants and established the concentration limit ($5\;{\mu}g/m^3$) in the air and is going to apply the standard from 2010. Benzene is emitted from various sources such as combustion plants, production processes, waste treatment facilities and also automobiles. Mobile source is known as one of the major emission sources of benzene. In this study, we estimated the domestic emissions of benzene from mobile source and compared the results with those of advanced countries. Mobile source was divided into 2 categories, Le., on-road source and non-road source. The total emissions of benzene from mobile source were estimated as 3,106 tons/yr and 1,612 tons/yr was emitted from on-road source and 1,494 tons/yr was from non-road source. Emission ratio of benzene from on-road source showed that 80.0% was from passenger cars, 10.1% was from taxis, 7.2% was from light-duty vehicles, 2.5% was from heavy-duty vehicles and 0.2% was from buses. In the case of non-road source, the distribution showed that 66.3% was from construction machineries, 14.5% was from locomotives, 11.7% was from ships, 7.1% was from agriculture equipments and 0.5% was from aircrafts. The cold-start emissions were estimated as 942 tons/yr and this value was almost 1.5 times greater than that for hot engine emissions (608 tons/yr). In addition, the fuel-based distribution was 65.9%, 31.1% and 2.8% from gasoline, LPG and diesel vehicles, respectively. The emission ratio from mobile source occupied 65% and 30% of total benzene emissions in USA and UK, respectively. In case of Korea, the emission ratio of benzene from mobile source occupied 29% (15% from on-road source, 14% from non-road source) which showed similar value with UK.