• Journal of ILASS-Korea
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• v.15 no.1
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• pp.25-30
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• 2010

The capability of pilot injection with small fuel quantity at all engine operating conditions is one of the main feature of the common rail direct injection system. The purpose of the pilot injection is to lower the engine noise and to reduce the NOx emissions. This study describes the pilot spray structure characteristics of the common-rail diesel injectors with different electric driving characteristics, including solenoid-driven and piezo-driven type. Namely three common-rail injectors with different electric current wave were investigated in this study. The pilot spray characteristics such as spray speed, spray tip penetration, and spray angle were obtained by spray images, which is measured by the back diffusion light illumination method with optical system for high-speed temporal photography. As this research results, it was found that pilot injection of common-rail system was effected by rate of injection with different electrical characteristic for driving the injector.

• Transactions of the Korean Society of Machine Tool Engineers
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• v.14 no.6
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• pp.95-100
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• 2005

Since air pollution has become a globally critical issue and exhaust emissions from automobiles cause a major source of air pollution, many countries including advanced countries have stipulated stringent emission regulations. This research focused on engine performance characteristics with the application of a continuous regeneration diesel particulate filter and EGR together in a heavy duty vehicle, and gives some suggestions on the direction of designing points of view by comparing the experimental data with numerical results which were obtained through KIVA-3V.

• Transactions of the Korean Society of Automotive Engineers
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• v.11 no.4
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• pp.37-43
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• 2003

The exhaust gas recirculation (EGR) is needed for one of various strategies to reduce NOx emission. But to get the proper EGR rate, the intake and exhaust system become complicated, also application of EGR system is difficult because of the penalty in fuel consumption and the increase in particulate matter. This study is focused on the development of EGR valve using the electrical method. The effects of EGR on the characteristics of NOx, CO, CO2 emissions and particulate mater have been investigated using small-displacement size 0.8-liters engine of diesel passenger car operating at several loads and speeds. After the analysis and comparison between conventional E-EGR valve and developed E-EGR valve performance by test bench, the estimation of vehicle application was executed through the EGR map and CVS-75 test result measured on the chassis dynamometer.

• 연구논문집
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• s.24
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• pp.5-11
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• 1994

EGR is an efficient method for reduction of NOx from diesel exhaust emission since it is simple to install with low cost and effective in its performance however it has demerits such as incresing wear on the moving parts of engines. stainning intake system and deteriorate lubricating oil. In order to reduce the soot contents in the recirculating gas to intake system of the engine, a proper filtering device was desined and manufactered for experiment system. It is aimed to grasp the characteristics of pollutant emissions including SFC on EGR system equipped with soot removal device.

• Journal of Practical Engineering Education
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• v.6 no.2
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• pp.127-134
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• 2014

Analyzing test data of a vehicle for evaluating its emission performance is an essential process in automotive development field, yet it is intricate and tedious task. In addition, clear understanding and care are required when the analysis process is carried out. Computer software solutions significantly reduce the time and the effort for such analysis. Developing a computer routine to analyze the emission data in a vehicle test demands a complete understanding of the emissions analysis and its related details. In this paper, the principals to develop a LabVIEW analysis routine (VI) are introduced helping automotive engineers comprehend the emission analysis process of a vehicle test data and instruct them to develop similar routines for such analysis.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.30 no.4
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• pp.394-404
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• 2020

Objectives: The aims of this study are to derive the characteristics of diesel exhaust gas emissions generated during vehicle checking in the garage of fire stations and of the related improvement plans for proper air quality management. Methods: The researcher measured changes in the air quality inside garages according to the operating conditions of the exhaust facility and before and after vehicle checking at three fire stations. Results: During the checking of fire engines, a large volume of hazardous substances exceeding management standards were generated, and improvement of the discharge facilities was required for proper air quality management. Conclusions: It is necessary to study the hazard evaluation of firefighters' exposure to exhaust gas, to operate exhaust gas ventilation facilities, and to prepare technical standards for proper indoor air quality management.

• Journal of ILASS-Korea
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• v.26 no.4
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• pp.163-170
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• 2021

Emergency generators normally use diesel engines. The generators need to conduct weekly no-load operation inspections to ensure stable performance at emergency situations. In particular, the generators with large diesel engines mainly use rectangle type filter substrates. In order to minimize hazardous emissions generated by generators, optimizing the reduction efficiency through CFD analysis of flow characteristics of PM/NO_X reduction system is important. In this study, we analyzed internal flow by CFD, which is difficult to confirm by experimental method. The main factors in our numerical study are the changes of flow uniformity and back pressure. Therefore, changes in flow characteristics were studied according to urea injector locations, selective catalyst reduction (SCR) diffuser angle, and filter porosity.

• Journal of Hydrogen and New Energy
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• v.31 no.3
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• pp.307-313
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• 2020

The 3.9 liter diesel engine with a mechanical fuel injection system was converted to di-methyl ether (DME) engine and performance optimized. In order to switch to the DME engine, the plunger of the high pressure fuel pump was replaced and the diameter of the injector nozzle was increased. Through this, the disadvantage of DME having low calorific value per volume can be compensated. To optimize the performance, the number of injector nozzle holes, injector opening pressure, and fuel injection timing were changed. As a result, the optimum number of injector nozzle holes was 5, the injector opening pressure was from 15 MPa to 18 MPa, and the injection timing was 15 crank angle degree before top dead center (CAD BTDC). The power was at the same level as the base diesel engine and nitrogen oxides (NOx) emissions could be reduced.

• Journal of Power System Engineering
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• v.20 no.1
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• pp.18-23
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• 2016

As diesel engines have high power and good fuel economy on top of less $CO_2$ emissions, their market shares are increasing not only in commercial vehicles but also in passenger cars. LNT, urea-SCR and combination of them have been developed for after-treatment of the exhaust gas to reduce NOx on diesel vehicles. The aim of this study is to investigate the $NH_3$ generation characteristics of LNT catalyst downstream. It was found from the experiments of the LNT catalyst that $H_2$ was useful as a reductant in SCR catalyst because it can enhance the de-NOx performance and improve $NH_3$ selectivity. The $NH_3$ generation of the LNT, when hydrothermally aged at $900^{\circ}C$ for 18 hr, increased to about 90ppm at $300^{\circ}C$ due to Pt sintering and Ba agglomeration. LNT catalyst was most sulfur poisoning at $500^{\circ}C$. The $NH_3$ slip increased due to the reduction of residence time according to SV increase.

• Transactions of the Korean Society of Automotive Engineers
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• v.8 no.6
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• pp.79-86
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• 2000

The effects of recirculated exhaust gas on the wears of piston and piston rings were investigated by the experiment with a two-cylinder, four cycle, indirect injection diesel engine operating at an engine load of 75% and an engine speed of 1600 rpm. For the purpose of comparison between the wear rates of two cylinders with and without EGR, the recirculated exhaust gas was sucked into one of two cylinders after the soot contenets in exhaust emissions were removed by an intentionally designed cylinder-type scrubber equipped with 6 water injectors(A water injector has 144 nozzles of 1.0 mm diameter), while only the fresh air was inhaled into the other cylinder. These experiments were carried out on the fuel injection timing fixed at 15.3$^{\circ}$ BTDC. It was found that the wear rate of piston skirt with EGR increased a little bit, but the piston head diameter increased, rather than decreased, owing to soot adhesion and erosion wear, and especially larger with EGR, and that the wear rates of the top and second piston ring(compression ring)thickness with EGR were more than twice the wear rate of top ring in case of no EGR, but the wear rate of oil rings thickness without EGR increased greater than that with EGR.