• Journal of the korean Society of Automotive Engineers
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• v.10 no.6
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• pp.48-53
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• 1988

In a previous report, the properties of vegetable oils as diesel fuel substitutes were investigated and the basic load performance of a diesel engine was examined using vegetable oil. The results show that despite of the long term chain hydrocarbon structure and large droplet size due to high viscosity, vegetable oils have good basic performance and exhaust emissions, however they cause serious problems as carbon deposit buildup, they have poor durability, and also poor thermal efficiency. In this paper, the startability and engine durability with long term operation was tested by physical methods for reducing viscosity when vegetable oil was used as compared against diesel fuel. The results obtained in this investigation may be stated as follows; (1) There is no problem in startability when vegetable oil was used as diesel fuel substitutes as far as fuel temperature is higher than 30.deg. C (2) The carbon deposits were most extensive at lower loads and lower engine speeds, and deposit buildup more heavily on the cooler parts of the combustion chamber wall. (3) Blends with 25% diesel fuel and 20v-% ethanol are effective in reducing the carbon deposit buildups. (4) Significant improvement in carbon deposit and piston ring stick can be obtained by heating fuel(200.deg.).

• Transactions of the Korean Society of Automotive Engineers
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• v.9 no.2
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• pp.1-10
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• 2001

In order to reduce hydrocarbon emissions of spark ignition engine, it is important not only to improve catalyst conversion efficiency but also to reduce direct engine out hydrocarbon emissions, during cold starting and warm up process. Tjerefore many researchers have been attracted to develop an early fuel evaporator (EFE) by introducing a ceramic heater for a solution of engine out hydrocarbon emissions in SI engine. But, the performance of the EFE in MPI engine to reduce the exhaust emissions and to improve the cold startability has nat been clarified yet. The purpose of this study is to evaluate the feasibility of a glow plug for EFE.

• Journal of the korean Society of Automotive Engineers
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• v.14 no.3
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• pp.71-79
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• 1992

Recently, air pollution and energy security problems have necessitated the development of alternative fuel vehicles. As an alternative fuel vehicle FFV(Flexible Fuel Vehicle) which can be operated by and mixture between gasoline and M85(methanol 85% and gasoline 15% by vol. percent) has been drawing great attention. But poor cold startability of high methanol- content fuel which is characteristic of lower fuel volatility and higher latent heat of vaporization than gasoline is one of the major problems to be solved for the development of FFV. In this paper, important factors influencing cold startability of general S.I. engines are described. And, so-me cost-effective and practical methods were investigated in view of the optimization of fuel-ing parameters and ignition system for M85 fuel. The test results showed good startability up to (-22)-(-23).deg.C.

• Transactions of the Korean Society of Automotive Engineers
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• v.10 no.4
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• pp.7-14
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• 2002

In order to reduce exhaust omissions of spark ignition engine, it is important not only to improve catalyst conversion efficiency but also to directly reduce engine out exhaust emissions, during cold starting and warm up process. Therefore many researchers have been attracted to develop an early fuel evaporator(EFE) by Introducing a ceramic heater fur a solution of engine out exhaust emissions in SI engine. But, the performance of the EFE in MPI engine to reduce the exhaust emissions and to improve the cold startability has not been clarified yet. The purpose of this study is to evaluate the feasibility of a glow plug far EFE. Impinging spray using heated and unheated glow plug helps the vaporization of the fuel and heat up the three way catalyst sufficiently. The amount of CO, and UHC is reduced overall. The amount of NOx is higher at the initial stage, but become lower as time goes on than without glow plug.

• Proceedings of the KSME Conference
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• 2008.11b
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• pp.2910-2915
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• 2008

This paper was investigated the behaviors of the engine and combustion phenomena for various LPG compositions in the semi-return type system, which is not recircurated to LPG tank through furl rail, applied LPi engine during a cold idle condition and including a cold start of the engine. Cyclic HC and NOx emissions were measured at exhaust port to examine their formation mechanical and reduction mechanical with fast response gas analyzers. Various ignition timing is experimented to study the characteristics of combustion phenomena, HC/NOx emissions during fast idle. Also, this study was investigated start delay time, cylinder pressure, HC/NOx emissions, Mass Fraction Burned, starting time to evaluate performance of transient cold startability. Compared to the return type system, the semi-return type system have advantages in point of production cost and equivalent performance of engine starting time and pressure settling time.

• Transactions of the Korean Society of Automotive Engineers
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• v.24 no.6
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• pp.619-626
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• 2016

The new 1.4 L turbocharged LPG direct injection (T-LPDI) engine is presented in this paper to improve the fuel efficiency of the vehicles installed with the 2.0 L LPG port fuel injection (LPI) engine, while maintaining the performance as a downsizing concept for the new engine platform development. Firstly, the return type high pressure LPG fuel supply system is designed and mounted in the new 1.4 L T-LPDI engine. As a result, this new engine shows a much better WOT performance and approximately 8 % of improved fuel economy level, as compared to the 2.0 L LPI vehicle. Secondly, the LPDI engine specific optimized design for high pressure fuel components and fuel injection control strategies are proposed and evaluated in order to overcome the restartability problem in a heat-soaked condition called the vapor lock phenomenon. Consequently, these experimental results illustrate a great potential for the developed 1.4 L T-LPDI engine as a possible substitute for the 2.0 L LPI engine.

• Journal of the Korean Society of Propulsion Engineers
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• v.14 no.2
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• pp.10-18
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• 2010

Scramjet engine is one of the core parts of hypersonic vehicle of next generation and being investigated by many countries. Korea Aerospace Research Institute performed a ground test of the model scramjet engine S1 in 2007. And, S2 model which is improved from S1 model in engine startability and thrust was tested with HIEST (High Enthalpy Shock Tunnel) at Kakuda Space Center of JAXA. Design condition of S2 model was Mach 6.7, however, it was tested at Mach 7.7 as an off-design condition test. As a test result, flow separation was found at the inside of the intake, but the engine showed stable combustion pressure distribution. Furthermore, compared to other test models, S2 model showed a good performance value in thrust and specific impulse.

• Transactions of the Korean Society of Automotive Engineers
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• v.11 no.4
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• pp.7-14
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• 2003

Recently, LPG has been considered as more environmental friendly fuel than liquid fuels for vehicles. However because LPLi engine has the strong point that not only increases the volumetric efficiency and cold startability, but also decreases unburned hydrocarbon exhaust emission in warm-up condition, much attention has moved to development of the Liquid Phase LPG injection (LPLi) system from the mixer type LPG engine. To reduce exhaust NOx, this study investigated the effect of EGR with LPLi engine and determined optimized EGR feeding position and distribution. In addition, engine stability, performance, and exhaust emission level were evaluated.

• Journal of Mechanical Science and Technology
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• v.16 no.7
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• pp.942-949
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• 2002

The use of a combined starter/generator integrated into the drive train of an automobile offers several possibilities for improvement of fuel economy The use of such a starter/generator system is made feasible by a switch from a 14 volts electrical system to a 42 volts system, however, the sizing of the components is not a trivial problem. This study combines a dynamic electromechanical model of the starter, battery and power electronics with the nonlinear mechanics of the piston/crankshaft system and a thermofluid model of the compression and expansion processes to investigate the cold start problem. The example involves the start of an eight cylinder engine at -25 degrees Celsius. This paper shows how the mechatronic V8 engine of an automotive starter/generator system for the startability works well.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.31 no.3 s.258
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• pp.234-241
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• 2007

The regulations for hydrocarbon emission from vehicles have become much more stringent in recent years. These more stringent regulations request vehicle manufacturers to develop the advanced exhaust system for reducing exhaust emissions. The exhaust emissions has many sources in vehicle. In order to investigate the characteristics of hydrocarbon(HC) in the exhaust manifold, concentrations of individual HC species were measured in exhaust process. Using sampling valve, the light hydrocarbon emissions were captured in the exhaust manifold(catalyst before and after) and analyzed from LPLi engine exhaust manifold(catalyst before and after) using different fuel properties. Then exhaust samples were measured by gas chromatography(GC) and exhaust gas analyzer. Catalyst conversion efficiency for fuel properties of Butane 100% was better than Propane 100%. Start delay of LPLi engine was observed as increment of propane contents in LPG fuels.