• Transactions of the Korean Society of Mechanical Engineers
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• v.18 no.12
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• pp.3326-3334
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• 1994

To theoretically predict knock occurrence in S. I. engine as a function of engine design and operating parameters, transient local temperature and pressure, mixture density of flame front in combustion period are calculated. We next determined normal combustion period and auto ignition period of end gas using the prediction method on occurrence of spark knock which we suggested. We predict knock occurrence in S. I. engine by comparing consecutively normal combustion period with the auto ignition period of end gas in combustion period. Engine design and operating parameters such as compression ratio, engine speed, spark timing, inlet temperature and pressure are taken into account in this calculations. The predicted result are well matched with the experimental results in turbocharged engine. Therefore, this method will provide the systematic guideline for designing engines in view of knocking limits.

• Journal of the korean Society of Automotive Engineers
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• v.4 no.2
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• pp.69-78
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• 1982

The purpose of this study is to investigate the flame propagation phenomenon in the combustion chamber of spark-ignition gasoline engine for the idling condition. by means of four ion probes located through the cylinder head, the time intervals for the flame to arrive at the respective probes are read on th visicorder char. As results, the flame is considered to initiate after some ignition delay and to propagate through the central space of combustion chamber with rather constant speed on the order of 25m/sec, and thereafter to be slowed down approaching the wall. Additionally, the retardation of flame in the wall boundary layer could be inferred. The maximum pressure is developed when the flame nearly touches the wall diagonal to the spark plug. And some features of flame propagation are elucidate.

• Transactions of the Korean Society of Automotive Engineers
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• v.7 no.5
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• pp.9-15
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• 1999

A digital CDI(Capacitive Discharge Ignition) system on small two stroke motorcycle engine was developed in this paper, This CDI system with microprocessor as its main part has more flexible spark timing than the conventional CDI system because of its programmable characteristics. The principle of this digital CDI system and the design methods of hardware and software were presented in this paper, Two stroke small engine was tested to investigate the performance of digital CDI system And also this system was investigated to optimize the engine performance. Also comparison between conventional CDI can provide better spark timing variation than the conventional system. The part and full load test results show that the engine power was increased about 10-20% and fuel consumption was decreased about 10-20% simultaneously. Furthermore, this digital CDI system has simple structure, low cost and very little modification are required. It is a promising technology to substitute for the widely used conventional CDI system.

• Transactions of the Korean Society of Automotive Engineers
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• v.2 no.5
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• pp.30-40
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• 1994

The direct-injection stratified-charge engine has the advantages of higher thermal efficiency and less CO and $NO_x$ emission levels than conventional spark ignition engines. However, its actual utilization is prevented by high unburned hydrocarbon emission levels during light-load operations. In this paper, fundamental studies were carried out using a pancake type constant volume bomb. The effects of intensification of local premixing by tangential and radial fuel injection were examined experimentally. Unburned hydrocarbon emission levels with radial fuel injection were shown to be lower than those of tangential fuel injection cases. The stratification and mixing process of fuel jet and combustion process were observed by schlieren photography.

• Transactions of the Korean Society of Automotive Engineers
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• v.12 no.2
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• pp.45-53
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• 2004

An experimental study was carried out to obtain the fundamental data about the effects of radicals induced injection on premixture combustion. A constant volume combustor divided to the sub-chamber and the main chamber was used. The volume of the sub-chamber is set up to occupy less than 1.5％ of that of whole combustion chamber. Radial twelve narrow passage holes are arranged between the main chamber and the sub-chamber. The products including radicals generated by spark ignition in the sub-chamber will derive the simultaneous multi-point ignition in the main chamber. While the equivalence ratio of pre-mixture in the main chamber and the sub-chamber is uniform. We have examined the effects of the sub-chamber volume, the diameter of passage hole, and the equivalence ratio on the combustion characteristics by means of burning pressure measurement and flame visualization. In the case of radical ignition method(RI), the overall turning time including the ignition delay became very short and the maximum burning pressure was slightly increased in comparison with those of the conventional spark ignition method(SI), that is, single chamber combustion without the sub-chamber. The combustible lean limit by RI method is extended to more ER=0.25 than that by SI method. Therefore the decrease of every emission including NOx and the improvement of fuel consumption is anticipated due to lean burn.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.10 no.7
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• pp.1433-1438
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• 2009

The purpose of this study is to investigate how the ignition spark timing conversion influences the engine performance of LPG/Gasoline Bi-Fuel engine. We propose the control system which can advance the ignition spark timing in LPG fuel mode more than used in gasoline fuel mode. In order to investigate the engine performance during combustion, engine performance are sampled by data acquisition system, for example cylinder pressure, pressure rise rate and heat release rate, while change of the rpm(1500, 2000) and the ignition timing advance($5^{\circ}$,$10^{\circ}$,$15^{\circ}$,$20^{\circ}$) As the result, between 1500rpm and 2000rpm, the cylinder pressure and pressure rise rate was increased when the spark ignition was advanced but pressure rise rate at $20^{\circ}$was smaller value. Also, the heat release rate at 1500rpm was increased but it was lower around $20^{\circ}$at 2000rpm.

• Journal of Hydrogen and New Energy
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• v.28 no.2
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• pp.225-230
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• 2017

Coal oil is widely used as a home heating fuel for portable and installed coal oil heaters. Today, Coal oil is widely used as fuel for jet engines and some rocket engines in several grades. This paper describes the performance characteristics according to the compression ratio of spark ignition engine fuelled with coal oil. As a result, the following knowledge is obtained: As the compression ratio is decreased, there is an increase in torque, indicated mean effective pressure (IMEP), heat release rate, and brake thermal efficiency. Higher compression ratio of the engine decreases the ignition delay period, combustion period, and cooling loss.

• Journal of Korean Society for Atmospheric Environment
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• v.26 no.5
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• pp.469-474
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• 2010

Gasoline engines have proven their utility in light, medium and heavy duty vehicles. Concern about long term availability of petroleum and the environment norms by the increased vehicular emission have mandated the search for safe fuel. CNG is an environmentally clean alternative to the existing spark ignition engines with the advantages of minimum change. A higher octane number and a higher self ignition temperature make it an attractive gaseous fuel. The thermal efficiency is better than gasoline for the same engine. The reduced carbon mono oxide, carbon di-oxide, hydrocarbon emissions is a favorable outcome along with a slight increase in $NO_x$ emission when compared with gasoline fuel to a dual fuel mode in the existing spark ignition engines. The result from the experiment shows that CNG could be a potential substitute fuel that maintains performance and emissions characteristics in gasoline engines.

• Journal of Energy Engineering
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• v.16 no.1 s.49
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• pp.1-6
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• 2007

The purpose of this study was to investigate the reduction of exhaust gas temperature in a LPG engine that had been converted from a diesel engine. A conventional diesel engine was modified to a LPG (Liquefied Petroleum Gas) engine by replacing the diesel fuel injection pump with a LPG fuel system. The research was performed by measuring the exhaust gas temperature upon varying spark ignition timing, airfuel ratio, compression ratio, and different compositions of butane and propane. Engine power and exhaust temperature were not influenced by various butane/propane fuel compositions. Finally, among the parameters studied in this investigation, spark ignition timing is one of the most important in reducing exhaust gas temperature.

• Journal of the Korean Society of Safety
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• v.7 no.1
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• pp.31-38
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• 1992

This paper presents a study on application of expert system technique for the diagnosis of fire-causes in plants. A need is recognized for new methods to diagnose exactly the causes of fires without the help of the human experts. To cope with the difficulty, the expert system techiuque is applied to this area. The expert system suggested in this paper is developed to infer the causes of fires(or, ignition source ) by using the information drawn from the circumstances in fire. For the convenience of inference, ignition sources we classified into eight types ; elecoic spark, adiabatic compression, welding spark, material of high temperature, impact and friction, spontaneous ignition, naked fire, and static electricity. The knowledge base is composed of the rule base and dynamic database, which contain the rules and facts obtained by the expenence in this area, respectively. Both depth-first search and backward chaining schemes are used in reasoning process. This expert system is written in an artificial intelligence language "PROLOG", and its availability is demonstrated through the case study.