• Journal of ILASS-Korea
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• v.21 no.3
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• pp.130-136
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• 2016

NOx and PM are important air pollutants as vehicle management policy aspect. Medium-duty truck is the main source of the pollutants although the vehicle market share is only 3.5%. National emission portion of NOx and PM form the mobile sourece are 14% and 16% respectively. In this study it was investigated that characteristics of air pollutants emission on medium duty truck equipped with EGR and SCR system. Vehicle's test reflected driving cycle on the chassis dynamometer, and applied test cycle was WHVC(World Harmonized Vehicle Cycle) mode. The test cycle include three segments, represent urban, rural and motorway driving. Based on the test results NOx, PM, HC were less emitted form SCR vehicle than EGR vehicle. And CO was less emitted form EGR vehicle than SCR vehicle due to CO oxidation reaction on DPF surface. And most air pollutants reduced as average vehicle speed increased. Pollutants were less emitted on motorway section than urban and rural sections. But highly NOx emission on motorway section was verified according to increased EGR ratio on fast vehicle speed. HC and CO additional emission was identified as 68%, 58% respectively during SCR vehicle's cold engine start emission test. NOx additional emission was detected by 24% on SCR vehicle's condition of engine cold start while not detected on vehicle equipped with EGR. SCR vehicle's additional NOx emission was derived from low reaction temperature during engine cold start condition. medium-duty truck emission characteristics were investigated in this study and expected to used to improve air pollutants management policy of medium-duty truck equipped with SCR & EGR.

• Journal of Environmental Science International
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• v.16 no.2
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• pp.179-185
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• 2007

Nitrous oxide ($N_2O$) is an important trace gas in the atmosphere not only because of its large global warming potential (GWP) but also because of the role in the ozone depletion in the stratosphere. It has been known that soil is the largest natural source of $N_2O$ in global emission. However, anthropogenic sources contributing from industrial section is likely to increase with rising the energy consumption, and transportation as well. In this study, a total of 32 gasoline-powered passenger vehicles (ranging from small to large engine's displacement and also ranging from aged catalyst to new catalyst) were tested on the chassis dynamometer system in order to elucidate the characteristics of $N_2O$ emission from automobiles under different driving modes. Ten different driving modes developed by NIER were adapted for the test. The results show that the $N_2O$ emission decreases logarithmically with increase of vehicle speed over the all test vehicles ($N_2O$) emission = -0.062 Ln (vehicle speed) + $0.289,\;r^2=0.97$). It revealed that the larger engine's displacement, the more $N_2O$ emission were recorded. The correlation between $N_2O$ emission and catalyst aging was examined. It found that the vehicles with aged catalyst (odometer record more than 8,0000km) emit more $N_2O$ than those with new catalyst. Average $N_2O$ emission was $0.086{\pm}0.095\;N_2O-g/km$ (number of samples=210) for the all test vehicles over the test driving modes.

• Journal of Korean Society for Atmospheric Environment
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• v.27 no.2
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• pp.181-190
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• 2011

The air pollutants from vehicle exhaust gas are affected by many factors including fuel qualities, engine and vehicle technologies, driving patterns. In particular, fuel qualities and after-treatment devices could directly affect the emission level of pollutants. The pollutant reduction characteristics that caused by enforced fuel quality standard were analyzed. Three types of test fuel were selected in accordance with Korean automotive fuel standard in 2006, 2009, 2012 and used for vehicle emission test in chassis dynamometer. European COPERT correction equation of fuel impact was considered as reference information to quantify the vehicle emission test results. The contribution rates of exhaust emission by COPERT correction equation showed that aromatic compounds and oxygen contents in gasoline fuel was most important. In case of diesel fuel, cetane index and polycyclic aromatic compounds accounted for the greater part. The exhaust emission effects by COPERT correction equation revealed that CO and VOC was increased 0.86%, 1.57% respectively in after 2009 gasoline when compared to before 2009 gasoline fuel. In case of light-duty diesel vehicle CO, VOC and PM were decreased in range of 3~7%. The result from this study could be provided for developing future fuel standards and be used to fundamental information for Korean clean air act.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.25 no.3
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• pp.184-190
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• 2015

NVH engineering has become a hot issue due to radical technology changes and development in automotive industry since customers' expectations and needs for their vehicle is taken to a higher level. However, the source identification and quantification of the road noise within a vehicle is still not at the level where it needs to be to meet their expectations due to its' complex transfer path and difficulties in path optimization. The primary focus of this research is on direct force obtaining method at suspension hard points using suspension test rig. Directly obtained forces at suspension to body mounting points are critical and crucial for determining the effects of design changes of the suspension has on road noise performance. Direct force obtaining method has its limitation in sensor installation within an actual vehicle therefore, many has been indirectly calculating forces using full matrix inversion method or dynamic stiffness method. In this study, to circumvent this limitation, a suspension rig is used. Then, the suspension rig is verified through a comparative analysis of its dynamic behavior between the actual vehicle by cleat test on chassis dynamometer.

• Journal of Hydrogen and New Energy
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• v.23 no.6
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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.

• Journal of Hydrogen and New Energy
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• v.28 no.2
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• pp.220-224
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• 2017

Nitrogen dioxide ($NO_2$) is an important urban pollutant in Korea. Expecially, diesel vehicles are responsible for the most traffic rated nitrogen oxide ($NO_X$) emission, including nitric oxide (NO) and nitrogen dioxide ($NO_2$). Though nitrogen oxide ($NO_X$) emission from vehicle was applied a strict enforcement of emission standard, the specific $NO_2$ fraction in $NO_X$ ($NO_2/NO_X$) from various types of diesel vehicles was not understood. In order to investigate the fraction of $NO_2/NO_X$, the vehicle emission study was carried out at the facility of Transport Pollution Research Center (TPRC), National Institute of Environmental Research (NIER), Korea. Three different types of diesel vehicles(VAN, SUV, passenger) were tested on the NIER driving mode. The result of $NO_2/NO_X$ ratio was over 0.1 for all test vehicles and the highest $NO_2$ emission was observed at the van vehicle. The observation was showed that the emission trend of $NO_2/NO_X$ for passenger and SUV vehicles were inversely proportional. Also, as the emission standard has been strengthen, the emission rate of $NO_2$ has been decrease.

• Journal of Korean Society for Atmospheric Environment
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• v.21 no.6
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• pp.649-655
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• 2005

Automotive exhaust is suspected to be one of the main reasons of the rapid increase in greenhouse effect gases in ambient air. Although methane emissions are generally orders of magnitude lower than emissions of $CO_{2}$, the global warming potential (GWP) of methane is greater than that of $CO_{2}$. The environmental impact of methane emissions from vehicles is negligible and is likely to remain so for the foreseeable future. In this study, in order to investigate greenhouse gas emission characteristics from gasoline passenger cars, 20 vehicles were tested on the chassis dynamometer and methane emissions were measured. The emission characteristics by model year, mileage, vehicle speed were discussed. Test mode is CVS-15 mode that have been used to regulate for light-duty vehicle in Korea. It was found that $CH_{4}$ emissions showed higher for cold start, old model year and long mileage than hot start, new model year and short mileage, respectively. These results were compared with IPCC emission factors and the overall our results were anticipated to contribute for domestic greenhouse gas emissions calculation.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.37 no.5
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• pp.673-678
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• 2013

Creep groan noise occurs at low frequencies immediately after releasing brake pressure or when a car stops. This noise can be used to predict problems in not only the brake system but also the vehicle system. Because of its complexity, it is difficult to determine its characteristics. Therefore, most improvements are conducted by changing the brake pad, and it still remains difficult to conduct a test using a vehicle. In this study, the characteristics of creep groan noise and the effects from a vehicle system are investigated by using vehicles and an NVH chassis-dynamometer through various tests. A new evaluation method for creep groan noise by using a vehicle is proposed, and the possibility of reduction schemes from the viewpoint of the vehicle system is confirmed from the results mentioned above.

• Transactions of the Korean Society of Automotive Engineers
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• v.23 no.2
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• pp.161-168
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• 2015

Recently, due to various environmental problems such as global warming, increases of international oil prices, exhaustion of resource, a paradigm of world automobile market is rapidly changing from conventional vehicles using internal combustion engine to eco-friendly vehicles using electric power such as EV, HEV, PHEV and FCEV. Generally, in order to measure fuel consumption and pollutant emissions of cars, chassis dynamometer tests are performed on various driving cycles before actual driving test. There are many driving cycles for performance evaluation of conventional vehicles. However, there is a lack of researches on driving cycle for EV. In this study, the urban driving cycle for performance evaluation of electric vehicles was developed. This study is composed of two parts. In the part 1, the urban driving cycle 'GUDC-EV(Gwacheon-city Urban Driving Cycle for Electric Vehicles)' was developed by using driving data, which were obtained through actual driving experiment, and statistic analysis with chronological table. In this paper part 2, in order to verify the developed driving cycle GUDC-EV, virtual EV platforms were configured and simulations were performed with actual driving data using In addition, simulation results were compared with existing driving cycles such as FTP-72, NEDC and Japan 10-15.

• Transactions of the Korean Society of Automotive Engineers
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• v.15 no.3
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• pp.153-159
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• 2007

Nano-Particles are influenced on the environmental protection and human health. The relationships between transient vehicle operation and nano-particle emissions are not well-known, especially for diesel passenger vehicles with DPF. In this study, a diesel passenger vehicle was measured on condition of DPF regeneration and no regeneration on a chassis dynamometer test bench. The particulate matter (PM) emission from this vehicle was measured by its number, size and mass measurement. The mass of the total PM was evaluated with the standard gravimetric measurement method while the total number and size concentrations were measured on a NEDC driving cycle using Condensation Particle Counter (CPC) and EEPS. Total number concentration by CPC was $1.5{\times}10^{1l}N/km$, which was 20% of result by EEPS. This means about 80% of total particle emission is consist of volatile and small-sized particles(<22nm). During regeneration, particle emission was $6.2{\times}10^{12}N/km$, was emitted 400 times compared with the emission before regeneration. As for the particle size of $22{\sim}100nm$ was emitted mainly, showing peak value of near 40nm in size. This means regeneration decreased the mean size of particles. Regarding regeneration, PM showed no change while the particle number showed about 6 times difference between before and after regeneration. It seems that the regeneration influences on particle number emissions are related to DPF-fill state and filtration efficiency.