• Transactions of the Korean Society of Automotive Engineers
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• v.2 no.1
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• pp.116-127
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• 1994

A method using the linear matrix algebra is developed in order to determine unknown external forces in linear structural analyses. The method defines a matrix which represents the linearity of the vibrational analysis for a structural system. The unknown external forces are determined by the operations of the matrix. The method is applied to find an engine motion in an automobile system. For a simulation process, an exhaust system is modeled and analyzed by the finite element method. The validity of the simulation is verified by comparing with the experimental results the free vibration. Also, an experiment on the forced vibration is performed to determine the damping ratio of the exhaust sysetm. Estimated model parameters(natural frequency, mode shape) are in accord with the experimental results. Because the method merely repeats the transpose and inverse operations of a matrix, the solution is extremely easy and simple. Moreover, it is more accurate than the existing methods in that there is no artificial assumptions in the calculation processes. Therefore, the method is found to be reliable for the analysis of the exhaust system considering the characteristics of vibrations. Although the suggested method is tested by only the exhaust system here, it can be applied to general structures.

• Transactions of the Korean Society of Mechanical Engineers
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• v.16 no.9
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• pp.1736-1743
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• 1992

The combustion in the cylinder of spark ignition engine is completed after the delayed time that the liquid film fuel is vapourized as flowing into the combustion chamber. It is necessary to enhance the homogeneity of mixture and the combustion phenomenon in order to improve the heat efficiency and the emission characteristics of spark ignition engine. The main purpose of this paper is to manufacture a combustion analyzing system and examine closely the influence of non-uniformity due to the liquid film fuel flowing in the intake manifold on the combustion characteristics by using a 4 stroke multi- cylinder spark ignition engine. Moreover, with each cylinder, the interpretation of combustion characteristics by indicator diagram and the concentration of exhaust gas were investigated.

• Journal of Bio-Environment Control
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• v.22 no.2
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• pp.123-130
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• 2013

$CO_2$ enrichment systems have been recently used to shorten the growth period of plants and the improvement of harvest and its quality. To accomplish these goals, manifold should be designed to supply the same amount of $CO_2$. In this study, CFD approach has been used to understand the effects of geometric parameters, such as tube and hole diameters. An optimized geometry has been derived through pipe and tube part, respectively. As a result, the deviation of flow rate less than 0.1 g/s was expected at all holes of the $CO_2$ enrichment system.

• Transactions of the Korean Society of Automotive Engineers
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• v.24 no.5
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• pp.538-548
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• 2016

The purpose of this study is to identify the possibility of effective tuning works, understand the characteristics of tuning engine, and analyse the basic data of engine tuning inspection corresponding to the safe operation and environment of a driving gasoline car. The effects of tuning on the characteristics of performance and exhaust emissions under a wide range of engine speeds are experimentally investigated by the actual driving car with a four-cycle, four-cylinder DOHC, turbo-intercooler, water-cooled gasoline engine operating at four types of non-tuning, tuning 1, 2 and 3. The tuning parts in the gasoline engine are the intake manifold, intake pipe and air filter. In the experiment, the output, torque and air-fuel ratio of the five-speed automatic transmission vehicles were measured at the chassis dynamometer(Dynojet 224xLC) with one person on board. The exhaust emissions of $NO_X$, THC, CO, $O_2$ and $CO_2$, and excess air ratio(${\lambda}$) at the other chassis dynamometer(DASAN-MD-ASM-97-KR-HD) were also measured by the idle/constant-speed mode(ASM2525 mode) test method. It is found that the actual air-fuel ratios of non-tuning and tuning engines were shown to be lower than the stoichiometric air-fuel ratio with increasing engine speed, and the actual air-fuel ratio of non-tuning engine was slightly higher than those of tuning engines when the engine speed is more than 4000 rpm. The output was significantly increased by the tuning whereby the maximum output of tuning engine was more increased to approximately 117.64% than that of non-tuning engine. In addition, CO, THC and $NO_X$ emissions of non-tuning and tuning engines measured by the constant-speed test mode were all satisfied with the inspection standards. CO emission was increased, while THC and $NO_X$ emissions were reduced by tuning.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.11
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• pp.529-535
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• 2018

The range extender vehicle runs on a mechanism that allows the small power generation engine to start in the most efficient specific operating range to charge the battery and extend the mileage. In this study, we developed a step motor type intake air supply system that replaces existing throttle body system to develop a simple low cost control logic system. The system was applied to the existing base engine, and in order to improve the performance by increasing the amount of intake air, the effect of changing the length of the intake and exhaust manifold was experimentally examined. As a result, the Type B intake air control actuator operated by one step motor showed higher performance than the Type A in all the operation region, but the performance was lower than that of the base engine due to the increase of flow resistance. To improve this, it was confirmed that the engine performance was improved at both speeds of 2200rpm and 4300rpm when the 140mm adapter was installed in the intake manifold and when the newly designed 70mm exhaust manifold was applied. Through this process, high - precision operation control was realized by connecting the generator load to the optimized engine for the range extender electric vehicle. Experimental results showed that the speed change rate was within ${\pm}2.5%$ at 2200rpm in 1st stage and 4300rpm in 2nd stage and the speed follow-up result of 610 rpm/s was obtained when the speed was increased from 2200rpm to 4300rpm.