• Transactions of the Korean Society of Automotive Engineers
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• v.6 no.3
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• pp.97-105
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• 1998

High pressure injection is recently used to reduce the emissions and increase the power of DI diesel engine. This high pressure injection makes the spray strike the cylinder wall. This spray/wall impingement is known to affect the emission and performance of DI diesel engine such that it is very important to know the spray/wall impingement process. In this study, multidimensional computer program KIVA-II was used to clarify the effect of spray wall impingement by different injection spray angle with the spray/wall impingement model consiedering rebound and slide motion and also the improved submodel for liquid breakup, drop distortion model.

• Journal of Korean Society for Atmospheric Environment
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• v.14 no.4
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• pp.387-392
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• 1998

Recently, among after-treatment devices which have high possibility of utility, diesel oxidation catalyst (DOC) is concerned over the world. DOC oxidizes pollutants by means of activate-reaction during by -passing in the catalyst, in doing so, conversion efficiency of PM, CO and HC is high, and this device does not have an effect on engine performance because back pressure is not nearly increased. But, as a small amount of sulfur content in fuel is oxidized, it makes sulfate, which is absorbed on the surface of catalyst. So, in this study, the experiment is carried out by means of using ordinary fuel (0.1wt%) and low sulfur fuel (0.05wt%) with DOC, and the emission gas of diesel engine is measured.

• Transactions of the Korean Society of Automotive Engineers
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• v.4 no.2
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• pp.147-157
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• 1996

Natural gas is gaining more attraction as a future fuel in particular both for environmental protection and energy conservation. In order to bring about more widespread use of gaseous engines, the technology capable of achieving output and efficiency performance equivalent to that of diesel engines needs to be developed. In the present paper, the requirements of the pilot torch from pre-chamber for ensuring ignition and promoting combustion are discussed by means of taking high-speed flame photography and system can run with leaner mixture of various fuels comparing to the electric plug ignition system cause the ignition delay period ignited with the torch and the combustion period are very short in spite of changing A/F of gaseous fuels in the main chamber. However, the suitable piston-cavity design for the use of lower-hydrocarbon fuels such as propane and butane must be discussed increasingly in the mear future.

• Journal of the Korea Institute of Military Science and Technology
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• v.3 no.1
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• pp.92-105
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• 2000

Core technologies of powerplants, which are necessary for the development of Korean type combat aircraft, are analyzed. And then, the acquisition methodologies for the technologies are proposed. With respect to the aircraft engine design and manufacturing technologies, simple basic technologies such as component manufacturing and assembling technology come to close to those of advanced countries, but the core technologies were not acquired or in the understanding level only. Therefore, the research on the component manufacturing technology should be specialized for buildup of international competition first, and the research on core technologies such as high pressure compressor design, blisk, FADEC and hollow fan blade design should be concentrated step by step by taking an active participation in the development project of international cooperative aircraft powerplants.

• Transactions of the Korean Society of Automotive Engineers
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• v.10 no.3
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• pp.36-43
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• 2002

The characteristics of spray has much effect on performance and emissions for automobile, diesel engine, gas turbine and combustion engines. So spray behavior after impinging the wall is very important for prediction the engine performance. This studies examined about impingement spray considering ambient density(18,24,30kg/ms), temperature(293,473K), impingement angle(0,30,45°). The images of impingement spray were obtained by the high speed video camera. After that we analyzed impingement spray characteristics to use this images. In this experiment, we found that 1) The spray width is reduced by increasing the ambient gas density and temperature,2) The growth of downstream is increased by increasing the impingement angle.

• Transactions of the Korean Society of Automotive Engineers
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• v.11 no.5
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• pp.37-42
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• 2003

This research was carried on an 8100cc turbo-charged heavy duty diesel in the application of a cooled-EGR. Exhaust and intake manifold were modified and an electronically controlled EGR was installed in order to investigate engine performance and exhausted emission characteristics. High pressure route was designed in the compact form on the purpose of practicability in this cooled-EGR system, which constitutes a venturi tube to maintain pressure difference between exhaust manifold and compressor, an EGR cooler, an EGR valve and a solenoid valve.

• Journal of Mechanical Science and Technology
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• v.17 no.11
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• pp.1725-1731
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• 2003

A high level CVT ratio control algorithm is proposed to improve the engine performance by considering the powertrain response lag. In this algorithm, the desired CVT speed ratio is modified from the vehicle velocity, which is estimated after the time delay due to the powertrain response lag. In addition, the acceleration map is constructed to estimate the vehicle acceleration from the throttle pedal position and the CVT ratio. Using the CVT ratio control algorithm and the acceleration map, vehicle performance simulations are performed to evaluate the engine performance and fuel economy. It is found that the fuel economy can be improved about 3.6% for FUDS by the ratio control algorithm for the target vehicle. In selecting the appropriate time delay, compromise between the fuel economy and the acceleration performance is required.

• Transactions of the Korean Society of Automotive Engineers
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• v.2 no.2
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• pp.42-48
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• 1994

Turbocharging is one of the best methods to improve the performance of diesel engines, because of its merits,-power ratio, fuel consumption and exhaust emissions. Most of them in small and medium diesel engines have adopted the pulse turbocharging method with twin entry vaneless radial turbines to maximize the energy utility of exhaust gas. This method requires the high performance of turbine under unsteady flow, and also the matching between turbine and diesel engine is most important. However, it is difficult to match properly between them. Because the steady flow data are usually used for it. Accordingly, it is necessary to catch the characteristics of turbine performance correctly over the wide range of the operation conditions under unsteady flow. In this paper, the characteristics of turbine performance under unsteady flow are represented at varying conditions, such as inlet pressure amplitude, turbine speed and frequence.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.21 no.4
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• pp.291-298
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• 2011

According to the developments of automobile industry, the technology to enhance noise, vibration and harshness(NVH) performance has been studying in a point of view of ride comfort and quietness. Especially the use of computer aided engineering(CAE) simulation tools such as finite element(FE) analysis allows engineers to efficiently evaluate NVH performance. This paper presents the method to bulid FE models for full vehicle including engine, transmission. suspension and steering system, also to evaluate vibration performance of full vehicle. The full vehicle model, which is discussed, is correlated with the result of the frequency response measurement in the case of the car shake performance for high speed driving.

• 유체기계공업학회:학술대회논문집
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• 1999.12a
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• pp.33-40
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• 1999

Upgrade development of a high pressure ratio centrifugal compressor in marine engine turbochargers is presented. A new matched operating point at increased speed of rotation was determined through system cycle analysis using the exisitng test data of turbine performance. Under some severe restrictions for geometric parameters, the state-of-the-art methods of both aerodynamic design and CFD analysis were applied, in which only an impeller, a vaned diffuser and some part of casing wall were modified. Prototype hardware was fabricated and assembled for system performance tests. Excellent performance in pressure ratio and efficiency was obtained over whole speed region. Reduced surge and choke margin was, however, observed at design speed of rotation.