• Transactions of The Korea Fluid Power Systems Society
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• v.4 no.3
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• pp.13-21
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• 2007

A forklift is a motive machine powered by LPG, diesel engine or electric motors. The internal combustion engine type forklift is equipped with automatic transmission to meet the required drive load as well as the easy operation of the vehicle. This paper deals with the shift control and endurance test controller which is developed for the functional test of the newly designed automatic transmission on a dynamometer test bench. Its major function is to control the proportional solenoid currents, which is directly related to clutch pressures, for the given reference current trajectory during shift and sequential operation of shift schedule designed for the durability test at each gear. It also has the ability to monitor all the necessary test data through RS232 communication and log them to disk files. The current controller of embedded system is designed from the identified dynamics of solenoid coil and the current reference can be easily modified with a user interface software on PC so as to match the shift data by experiments.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.24 no.9
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• pp.1185-1194
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• 2000

The characteristics of intake port flow and engine performance with swirl ratio variance in a turbocharged D.I. diesel engine were studied in this paper. The intake port flow is important factor which have influence on the engine performance and exhaust emission because the properties in the injected fuel depend on the combustion characteristics. Through these experiments it can be expected to satisfy performance and emission by optimizing the main parameters; the swirl ratio of intake port, injection timing and compression ratio. The swirl ratio for ports was modified by hand-working and measured by impulse swirl meter. For the effects on performance and emission, the brake torque and brake specific fuel consumption were measured by engine dynamometer, NOx and smoke were measured by gas analyzer and smoke meter. The results of steady flow test are as follows; as the valve eccentricity ratio are closed to cylinder wall, the flow coefficient and swirl intensity are increased. Also we realized that there is a trade-off that the increase of swirl ratio decreases mean flow coefficient and increases the Gulf factor. And the optimum parameters to meet performance and emission through engine test are as follows; the swirl ratio 2.43, injection timing BTDC 13oCA and compression ratio 15.5.

• Transactions of the Korean Society of Automotive Engineers
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• v.22 no.5
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• pp.35-43
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• 2014

The automobile industry requires technological innovations to reduce fuel consumption with the public interest in environmental conservation in recent years. Thus, the hybrid system is applied not only to passenger cars but also commercial vehicles. The purpose of this paper is to develop engine ECU_ILS to develop commercial hybrid vehicles. In order to develop the engine and vehicle, the dynamometer and exhaust gas analyzer is needed. However, a lot of time and cost are required. In contrast, the model-based development environment that can be applied to a variety of test conditions can reduce development time. Therefore, a HILS system environment that can consider the behavior of actual vehicles for evaluation of the control logic, fuel consumption and exhaust gas is required. This engine ECU_ILS system was developed in this study, can analyze parameter such as the fuel injection rate, fuel injection time, fuel consumption and exhaust gas like the actual vehicle test using map data. Also, this system is expected to be able to analyze the characteristic of vehicle behavior and the development of peripheral device in relation to engine and vehicles. This HILS system can be used to develop control strategies of commercial hybrid vehicle systems in the future.

• Transactions of the Korean Society of Automotive Engineers
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• v.14 no.2
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• pp.145-150
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• 2006

Recently emission regulation on diesel vehicles is getting stringent and research on aftertreatment technology such as DPF and DOC has been carried out actively. Even though PM(Particulate matters) reduction efficiency in DOC is relatively low but the structure is simpler and very effective in the reduction of gas materials and unregulated materials. Therefore it has been applied to smaller diesel vehicles. The aims of this research is to investigate the emission reduction characteristics of DOC; DOC performance of regulated and unregulated material emission reduction. It results a Pt based catalyst demonstrated higher emission reduction efficiency than a Pt-V based catalyst in CVS-75 mode, and also the reduction efficiency of unidentified material was excellent.

• Journal of ILASS-Korea
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• v.14 no.4
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• pp.184-189
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• 2009

Recently, ultrafine particles emitted from internal combustion engine is main concern because of its well known adverse health effects. So Europe decided to start the regulation about diesel engine particle number emissions. The nanoparticles smaller than 50nm in diameter have the ability to penetrate deep into interstitial tissue of luge, where they may cause severe respiratory inflammation and acute pulmonary toxicity. Recent studies have showed that spark ignition engines emit particles number concentration comparable to those from diesel engines with DPF under high load and rich mixture conditions, including cold starts and acceleration. So this study investigated emission characteristics of ultrafine particles according to fuel injection type in gasoline vehicles and LPG vehicles. The test vehicles were tested on CVS-75 and NEDC vehicle test mode using the chassis dynamometer, CPC system applied as a particle measuring instrument at the end of dilution tunnel. As a result, the correlation between fuel injection type and particulate emission was determined. GDI vehicle emitted 10 times higher particles than PFI vehicles, and compared to Mixer and LPGI type LPG vehicle, LPLI vehicle emitted particles high.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.33 no.2
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• pp.79-84
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• 2009

Turbocharger has been widely used in many passenger cars in application with diesel engines because of high power and fuel efficiency. However, flow-induced noise (whoosh or hissing noise) which is generated within a compressor during its operation at marginal surge line can deteriorate noise characteristics. Hissing noise excitation is associated with the generation of turbulence within the turbocharger compressor and radiated through the transmission path in a turbocharger system. In this study, a expansion muffler with lids is devised and installed in the transmission path to reduce the hissing noise. Acoustic and fluid dynamic characteristics for the muffler are investigated which are related to the unsteadiness of turbulence and pressure in the turbocharger system. A transfer matrix method is used to analyze the transmission loss of the muffler. A simple expansion muffler with lids is proposed for the reduction of high frequency component noise. Turbulence simulation is carried out by a standard k - ${\varepsilon}$ model. An optimal design condition of the muffler is obtained by extensive acoustic and fluid dynamic analysis on the engine dynamometer with anechoic chamber. A significant reduction of the hissing noise is achieved at the optimal design of the muffler as compared with the conventional muffler.

• Journal of Korean Society of Environmental Engineers
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• v.36 no.7
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• pp.476-482
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• 2014

In this study, the characteristics of emulsified fuel and engine emissions were studied with engine dynamometer. Microexplosion took place in the combustion chamber. While combustion, emulsion fuel scattered to micro particles and it caused to smoke reduction. The heat produced from water vapour reduce the temperature of internal combustion chamber and it caused to inhibition of NOx production. It can be verified by the lower exhaust temperature of each ND-13 mode using emulsion fuel than that of MDO fuel. The NOx and smoke concentration were reduced by increasing water content in emulsion fuel. The power also decreased according to the increment of water content of emulsion fuel because emulsion fuel has low calorific value due to high water content than MDO. As a result of ND-13 mode test with 17% moisture content, it was achieved 24% reduction in NOx production, 76% reduction in smoke density, 11% reduction of $SO_2$ and 13% reduction in power loss.

• Transactions of the Korean Society of Automotive Engineers
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• v.20 no.5
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• pp.71-80
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• 2012

To improve the $NO_X$ conversion over a SCR (selective catalytic reduction) catalyst, the DOC (diesel oxidation catalyst) is usually placed upstream of the SCR catalyst to enhance the fast SCR reaction ($4NH_3+2NO+2NO_2{\rightarrow}4N_2+6H_2O$) using equimolar amounts of NO and $NO_2$. Here, a ratio of $NO_2/NO_X$ above 50% should be avoided, because the reaction with $NO_2$ only ($4NH_3+4NO+O_2{\rightarrow}4N_2+6H_2O$) is slower than the standard SCR reaction ($4NH_3+4NO+O_2{\rightarrow}4N_2+6H_2O$). In order to accurately predict the performance characteristics of SCR catalysts, it is therefore desired to develop a more simple and reliable mathematical and kinetic models on the oxidation kinetics of nitric oxide over a DOC. In the present work, the prediction accuracy and limit of three different chemical reaction kinetics models are presented to describe the chemicophysical characteristics and conversion performance of DOCs. Steady-state experiments with DOCs mounted on a light-duty four-cylinder 2.0-L turbocharged diesel engine then are performed, using an engine-dynamometer system to calibrate the kinetic parameters such as activation energies and preexponential factors of heterogeneous reactions. The reaction kinetics for NO oxidation over Pt-based catalysts is determined in conjunction with a transient one-dimensional (1D) heterogeneous plug flow reactor (PFR) model with diesel exhaust gas temperatures in the range of 115~$525^{\circ}C$ and space velocities in the range of $(0.4{\sim}6.5){\times}10^5\;h^{-1}$.

• Journal of ILASS-Korea
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• v.23 no.3
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• pp.136-148
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• 2018

Major countries have tighten their NOx regulation of diesel passenger cars. In the case of the EU, the regulation has been toughen up to 6.25 times since 2000. Despite the regulation the NOx concentration of the ambient has not been reduced proportionally. As these issues, to reduce NOx emission practically, Korea and the EU introduced the real-world driving emission (RDE) regulation and the test method that will be applied after 2017. In this paper, for the regulation to make a soft landing in Korea, 6 diesel passenger cars which met Euro 6a~6d regulation and were equipped with LNT/SCR were tested at a chassis dynamometer with environmental chamber applying the off-cycles (FTP, US06, SC03, HWFET and CADC) and several ambient conditions (-7 and $14^{\circ}C$) as well as certification modes (NEDC, WLTC@ $23^{\circ}C$). The result of the test showed that the ambient temp. and the engine load as a test mode impacted the NOx emission of the cars while the vehicles with SCR emitted NOx lower than with LNT. Additionally, to propose an effective RDE test method, the above result was compared with the results of the other papers which tested RDE using the same cars.

• Journal of Korean Society for Atmospheric Environment
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• v.22 no.1
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• pp.53-61
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• 2006

Recently, lots of researchers have been attracted to develop various alternative fuels and to use renewable fuels in order to solve the exhaust emission problems. DME (Dimethylether) is synthetic fuel, and can be produced from natural gas, coal and biomass. The emission is clean because it contains little sulfur and aromatic components In this study, the fuel was tested to investigate the applicability as an alternative fuel for diesel. This study was carried out by comparing the exhaust emissions and performance of diesel engine with DME, ULSD (ultra low sulfur diesel), LSD (low sulfur diesel) respectively. In order to measure regulated emissions, CO, $NO_{3}$, HC from vehicle different fuel types were used on chassis dynamometer CVS (constant volume sampler)-75 mode and EPA TO-I1A method was chosen for aldehydes analysis.