• Transactions of the Korean Society of Automotive Engineers
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• v.7 no.8
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• pp.24-33
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• 1999

This paper investigate the effects of the variations of engine operation condition in the flame kernel formation and developmnet . A model for calculating the initial kernel development in spark ignition engines is formualted. It considered input of electrical energy, combustion energy release and heat transfer to the spark plyg, cylinder head, and unburned mixture. The model also takes into accounts strain rate of initial kernel and residual gas fraction. The breakdown process and the subsequent electrical power input initially control the kernel growth while intermediate growth is mainly dominated by diffusion or conduction. Then, the flame propagates by the chemical energy and turbulent flame expansion. Flame kernel development also influenced by engine operating conditions, for example, EGR rate, air-fuel ration and intake manifold pressure.

• Transactions of the Korean Society of Automotive Engineers
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• v.10 no.1
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• pp.76-83
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• 2002

Mathematically and chemically simplified reaction scheme for n(heptane that simulates autoignitions of the end gases in spark ignition engines has been developed and studied computationally. The five(equation model is described, to predict the essential features of hydrocarbon oxidation. This scheme has been calibrated against autoignition delay times measured in rapid compression machines. The rate constants, activation temperatures, Ta, Arrhenius pre-exponential constants, A, and heats of reaction for stoichiometric nheptane/air has all been optimized. Comparisons between computed and experimental autoignition delay times have validated the present simplified reaction scheme. The influences of heat loss and concentration of chain carrier at the beginning of compression upon autoignition delay times have been computationally investigated.

• Transactions of the Korean Society of Automotive Engineers
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• v.11 no.3
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• pp.13-19
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• 2003

Mathematically simplified reaction scheme that simulates autoignitions of the end gases in spark ignition engines has been studied computationally. The five equation model is described, to predict the essential features of hydrocarbon oxidation. This scheme has been calibrated against autoignition delay times measured in rapid compression machines. The rate constants, activation temperatures, Ta, Arrhenius preexponential constants, A, and heats of reaction for stoichiometric n-heptane/air, iso-octane/air, and their mixtures have all been optimised. The optimisation has been guided by Morley's correlation of the ratio of chain branching to linear termination rates with octane number. Comparisons between computed and experimental autoignition delay times have validated the Present simplified reaction scheme and the influences of octane number upon autoignition delay times have been computationally investigated. It has been found that both cool flame and high temperature direct reactions can have an effect on autoignition delay times.

• Transactions of the Korean Society of Automotive Engineers
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• v.11 no.2
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• pp.89-95
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• 2003

We consider a problem of application of analytical redundancy to engine synchronization process of spark ignition engines, which is critical to timing for every ECU process including ignition and injection. The engine synchronization process we consider here is performed using the pulse signal obtained by the revolution of crankshaft trigger wheel (CTW) coupled to crank shaft. We propose a discrete-time linear model for the signal, for which we construct FDI (Fault Detection & Isolation) system consisting residual generator and threshold based on linear observer.

• Transactions of the Korean Society of Automotive Engineers
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• v.16 no.1
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• pp.127-133
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• 2008

Since the 1960's, exhaust gas recirculation(EGR) has been used effectively in spark ignition(SI) engines to control the exhaust emissions of the oxides of nitrogen(NOx). The most important requirements for the application of EGR systems to conventional SI engines are controllable flow rate and good dynamic response. In order to evaluate the characteristics of the electronic EGR valve, a test bench which is consisted of blower, heater, air flow meter and driving unit for electronic EGR valve was set up to simulate engine operating conditions. During the tests, the valve actuation parameters were controlled and the valve lifts and flow rates were measured to infer the characteristics of EGR valve. The results confirmed the capabilities of mathematical analysis and it seems that the correction for the valve lift and potentiometer output is necessary to achieve precise control of EGR rates.

• Proceedings of the KIEE Conference
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• 1999.07b
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• pp.693-695
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• 1999

In this paper, the adaptive nonlinear state observer is proposed to estimate the internal states and the nonlinearities of 4-cylinders 4-cycles spark ignition(SI) engines. The observed states and nonlinearities will be used to design the adaptive feedback linearization controller for reducing the fluctuation of idle speed. The simulation results are represented to show the validity of the proposed nonlinear observer-based adaptive controller.

• 제어로봇시스템학회:학술대회논문집
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• 2002.10a
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• pp.68.3-68
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• 2002

This paper presents a neural network approach to control exhaust gas recirculation(EGR) in a Liquefied Petroleum Gas(LPG) engine. In order to meet Increasingly stringent automotive exhaust emission regulations, alternative fuels such as LPG engines have been developed in many countries. HC&CO emissions of LPG engines can be easily reduced through air-fuel ratio control, but the control effect on NOx reduction is not good enough. Consequently EGR system is introduced to achieve a significant reduction in NOx emissions. Conventional EGR control uses the mapping method. The calibration time is long and the work is complex when adopting this mapping method. However neural networks are suitable f...

• Proceedings of the KSME Conference
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• 2000.11b
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• pp.757-763
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• 2000

In vehicle exhaust systems the sound attenuation and the reduction of flow losses are often two competing demands. The present study considers a fully vehicle exhaust system and investigates experimentally both the sound attenuation and the flow performance of production configurations including the catalyst, the resonator, and the muffler. Dynamometer experiments have been This study is on the development of a new muffler composed of a valve system using an elasticity of spring. The valve system conducted with the daewoo 1500cc Lanos engine with speeds ranging from 1000 to 5000 rpm. Measurements include the flow rates, the temperatures and the absolute dynamic pressures of the hot exhaust gases at point locations. The present study describes the experimental aspects of an ongoing effort to validate and use the nonlinear fluid dynamic models in the time-domain for the prediction of the acoustic and power performance of firing internal combustion engines with full production exhaust systems.

• Journal of the korean Society of Automotive Engineers
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• v.12 no.4
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• pp.66-74
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• 1990

Friction between piston-ring assembly and cylinder wall of a spark ignition engine was evaluated under various engine operating conditions utilizing a grasshopper linkage system. The friction force was estimated by the force balance relation at the small end of connecting rod. Three forces were chosen to be measured for the objective. They were gas pressure inside the cylinder, inertia force of the piston-ring assembly, and the force exerted by the connecting rod. These forces were measured by a piezo type pressure sensor, an accelerometer and strain gauges, respectively. Comparisons were made with the frictional force evaluated by the conventional method where the assumption of constant rotational speed of engines was adopted. Due to the variation of rotational speed of engines, the conventional method was found to lead to a large error in the evaluation of the frictional force.

• Journal of Aerospace System Engineering
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• v.18 no.1
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• pp.53-63
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• 2024

Adopting an engine igniter with high efficiency and ignition performance is essential for reliable operation of liquid rocket engines. In this study, we developed a spark torch igniter for a 450 N-scale methane-oxygen liquid rocket engine by conducting numerical analyses, igniter manufacturing and validation. Specifically, we conducted a parametric study for maximizing the enthalpy at the igniter exit, specifically by adjusting the mass flow rate, nozzle area ratio, fuel-oxidizer mixture ratio, and the igniter length-to-diameter. The heat transferred via the igniter nozzle exit was computed using 3-dimensional numerical simulations. We also manufactured and tested the igniter based on a deduced design to confirm ignition performance of the designed spark torch igniter. The igniter developed through this study could contribute to the development of practical propulsion systems such as upper-stage engines of small launch vehicles.