• Journal of the Korean Society for Precision Engineering
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• v.20 no.12
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• pp.183-190
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• 2003

In this paper, investigated are the machining characteristics such as material removal rate and machining time with respect to discharge area and capacitance in micro electrical discharge machining (MEDM). As discharge area determined by the electrode size and capacitance change, the optimal feedrate to allow the minimum machining time changes. The smaller discharge area is, the lower MRR becomes because of the area effect. As the capacitance increases, MRR also increases. However there is the limit capacitance beyond which the MRR does not increase anymore. As the discharge area increases, the limit capacitance also increases.

• Transactions of the Korean Society of Automotive Engineers
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• v.6 no.4
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• pp.47-55
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• 1998

A new ignition system concept was developed to improve ignition performance, accuracy of control and the reliability of the ignition system. The new ignition system has ho호 frequency discharge characteristics with 1.5-2.0 ms discharge duration, in place of the usual solitary longer duration event. We applied the system to a commercial engine to study its influence on the maximum combustion pressure attained during the cycle, when this peak pressure occurred, imep, variation rate of the engine speed and the flammability limit of a lean mixture. In this study, we clarified that the new ignition system had a beneficial effect of the lean mixture flammability limit. Also for a given mixture strength we found that the mew ignition system gave a higher peak cylinder pressure than in the case of the conventional ignition system.

• Transactions of the Korean Society of Automotive Engineers
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• v.23 no.6
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• pp.650-655
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• 2015

A high energy ignition system is essential for lean burn or high EGR gasoline engine, which is getting more and more interest to improve fuel economy. The high energy ignition systems comprise plasma jet, laser beam, corona discharge and so on. In this study, a high energy ignition system using corona discharge is developed and tested in a constant volume combustion chamber. The developed system shows extension of lean limit of propane-air mixture and enhencement of combustion speed. Various shape of corona discharge plugs are also tested and compared in this study.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.22 no.10
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• pp.8-17
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• 2008

This paper presents a stable lighting method for HID lamp for ship from initial discharging current limit with discharging voltage control. The output voltage of the proposed control scheme is boosted for ignition, and the charging voltage is decreased by the resistor discharging. The proposed controller fires the initial discharge at the designed discharging voltage to limit the discharge current. After the discharging, constant current controller is used for brightness in steady state. The proposed control scheme can limit the initial discharge current using the starting point control without a complex voltage controller. so it can improve the life-time of HID lamp and get a stable discharge from restricted the initial discharge current. In order to improve the protection of the system, a simple instantaneous error detecting circuit for open state and short state of HID lamp is used. The proposed error detecting of HID lamp can protect the power system of lamp control. The effectiveness of the proposed controller is verified from the experiments of practical 2.5[kW] HID search light for ship.

• Journal of the Korean Institute of Gas
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• v.2 no.2
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• pp.55-60
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• 1998

In this study, we investigated the dust explosion characteristics by determining minimum ignition energy and explosion limit for this experiment, we used pine-tree dust which was used widely for the filler of thermosetting resin. The experiment was accomplished according to the variation of discharge gap, dust concentration, particle size and humidity. The result of this experiment are as follows; (1) The relation between the discharge gap and ignition energy was that ignition energy decreased according as the discharge gap became small, but increased when the discharge gap was below 4mm and suddenly became infinite when the discharge gap was below. So, we knew that this infinite value was limit discharge gap. (2) When the dust concentration increase and the particle size became microscopic it was easy to explore and in the same particle size, if the humidity increase the minimum ingnition energy decreased.

• Nuclear Engineering and Technology
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• v.17 no.4
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• pp.267-278
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• 1985

Some kinds of methods have been applied to regulate the exposure doses by the radioactive effluents from nuclear power plants. The essential one is primary dose equivalent limit recommended by the ICRP. When the primary limit cannot be applied directly for regulation, there have been dose equivalent index in case of external exposure, or maximum permissible concentration, annual limit on intake, derived air concentration and maximum permissible body burden in case of internal exposure. But the derived limit is required from the viewpoint of discharge, for those values are inadequate to control discharge rate directly. This study was carried out to derive the release limit for the Wolsung nuclear power plant by the concentration factor method. This method is based on the assumption of steady state transfer between environment compartments.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.20 no.11
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• pp.3676-3685
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• 1996

Enhancement of the ignitability was necessary to realize the lean burn engine. The characteristics of multiple-spark capacitor discharge igniter(MSCDI) usefulness of which for lean burn was examined in constant volume combustion chamber and evaluated in spark ignition engine. Noise of MSCDI for engine was restricted by adoption of low voltage control system. It was found that the adaptability for high engine speed was remarkable. Lean limit in engine with MSCDI was extended 10% than conventional coil ignition system. Also maximum brake thermal efficiency was almost enhanced 1%.

• Journal of the korean Society of Automotive Engineers
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• v.11 no.5
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• pp.55-64
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• 1989

The effect of discharge have been investigated for condition of spark in a multiple spark ignition engine, as the spark duration, capacitive and inductive discharge energy were calculated for condition of spark by ignition wave and energy formula. The useful portion of spark discharge is divided into capacitance portion and inductance portion. It was found that capacitive discharge energy and spark duration were increased according to increasing number of spark, and inductive discharge energy was increased according to increasing spark interval. Therefore engine torque was increase and lean misfire limit was extended comparing with the standard ignition system. It found that spark energy was discharged within ignition delay period availability acted on the formation and growth of flame kernel, and total spark energy was increased according to increasing number of spark times, but discharged spark energy after ignition delay became unavailable energy. And the capacitive discharge energy has the dominant effect for stoichiomeric or not very rich air-fuel mixture but inductive discharge energy has the dominant effect for lean air-fuel mixture.

• Transactions of the Korean hydrogen and new energy society
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• v.28 no.2
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• pp.174-180
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• 2017

Recently, the world faces the environmental problem such as air pollution due to harmful gas discharged from car and abnormal climate due to the green-house gases increased by the discharge of $CO_2$. Compressed Natural Gas (CNG), one of alternative for this problem, is less harmful, compared to the existing fossil fuel, as gaseous fuel, and less carbon in fuel ingredients and carbon dioxide generation rate relatively favorable more than the existing fuel. However, CNG fuel has the weakness of slow flame propagation speed and difficult fast burn. On the other hand, hydrogen does not include carbon in fuel ingredients, and does not discharge harmful gas such as CO and HC. Moreover, it has strength of quick burning velocity and ignition is possible with small ignition energy source and it's has wide Lean Flammability Limit. If using this hydrogen with CNG fuel, the characteristics of output and discharge gas is improved by the mixer's burning velocity improved, and, at the same time, is possible to have stable lean combustion with the reduction of $CO_2$ expected. Therefore, this research tries to identify the characteristics of engine and emission gas when mixing CNG fuel and hydrogen in each portion and burning them in spark igniting engine, and grasp the lean combustion limit and emission gas characteristics according and use it as the basic data of hydrogen-CNG premixed engine.

• Journal of the Korean Society of Safety
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• v.15 no.2
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• pp.92-96
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• 2000

In this experiment, we studied about concentration characteristics of $NO_x$ and generation of ozone in the reactor of corona discharge type by using mixed gas of $NO/N_2$ and $N_2/O_2$. In the case of the initial NO concentration increased, decrease rate of NO concentration was weakened and discharge input power of minimum NO concentration became high. When NO concentration was high, NO decomposition limit was appeared. And NO reduction rate was decreased, when initial NO concentration and discharge input power increased. When discharge input power was 5W, we could know the most proper energy value for treatment of NO. When the concentration of initial NO increased, generation of ozone decreased and in the case of same concentration of NO, according to discharge input power increase, generation of ozone increased.