• 한국정보통신설비학회:학술대회논문집
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• 2006.08a
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• pp.19-23
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• 2006

Latching optical switches and optical logic gates AND and OR are demonstrated, for the first time, by the monolithic integration of a vertical cavity lasers with depleted optical thyristor structure, which have not only a low threshold current with 0.65 mA. but also a high on/off contrast ratio more than 50 dB. By simple operating technique with changing a reference switching voltage, this single device operates as two logic functions, optical logic AND and OR. The thyristor laser fabricated using the oxidation process achieved a high optical output power efficiency and a high sensitivity to the optical input light.

• Proceedings of the KIEE Conference
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• 2002.07c
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• pp.1717-1720
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• 2002

Electrodeless discharge lamps have been objects of interest and research for several decades, mainly because of their potential for extremely long life, high lamp efficacies and smaller than standard fluorescent lamps size. A series of measurements and observations concerning variables has yielded optical and electrical characteristics for electrodeless discharge lamp like incandescent lamp and circular lamp feature. Last experiment were carried out to determine the lamp temperature at several surface points during operation. Light output levels in excess over 60,000 cd/$m^2$ have been measured in electrodeless discharge lamp for a general of conditions. At lamp surface temperatures have been measured over $80^{\circ}C$, and starting current have been measured over ${\sim}A$.

• Proceedings of the KIEE Conference
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• 1998.07e
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• pp.1708-1710
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• 1998

In this study, several experiment is executed to analyze properties of Electrodeless Discharge Lamp using H-Discharge. 1. The operating frequency of this lamp is $2.45{\sim}2.65$[MHz] 2. The color of light is mild-white. And, it is shifted in the direction of red in low temperature. 3. In ambient temperature under $10^{\circ}C$, luminous efficiency is decreased precipitously. Therefore, research for improvement discharge-characteristic in low temperature need. 4. Discharge-characteristic stable between $160{\sim}240$[V]. And, luminous output is inverse proportion to coil-voltage. 5. When input-voltage is decreased continuously unstable section exist.

• Proceedings of the IEEK Conference
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• 2002.07c
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• pp.1390-1393
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• 2002

Comparative analysis of driving inverters for piezo-electric transformer (PT) is performed and the suit- able drive circuit for portable devices such as personal digital assistants (PDA) is chosen with the experiment in this paper. As a result, a single-switch inverter with a small two winding reactor is chosen, and then the advantages of this method are clarified. It is also confirmed that the driving inverter with this method enables to realize a stabilized AC 400v output and 82% power efficiency from DC 3V input under the conditions of the variations of load current or input voltage from the experiments. Piezo-electric Transformer, Back-Light System, Single-Switch Driving Circuits, Control Method

• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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• 2006.05a
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• pp.103-107
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• 2006

In this paper, the dimmable electronic ballast for the 250W metal halide lamp was realized by three stage structure. We developed stable the dimming ballast by using a Micro-controller, and measured the output wattage in the dimming range(illumination) from 100% to about 20%. Under the 35% dimming level, it is possible to cause the redution of lamp's life. The dimming performance can reduce the light system's wattage but can reduce the luminance efficiency (lux/watt).

• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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• 2003.11a
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• pp.169-173
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• 2003

This paper analyzes the effects of various operating voltages on the electrical and light output characteristics of 20mW(5mm-Ф), 1W and 5W high-power RGB LEDs. Operating voltages of three types are compared on a simple LED circuit: DC, full-wave rectified DC. and square-wave DC. As a result, it is found that the 1W and 5W high-power LEDs should be provided with appropriate heat sinks that hold down the increase of junction temperature. As for the operating efficiency the case of full-wave rectification gives the highest value.

• Proceedings of the KIEE Conference
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• 2005.07b
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• pp.1784-1787
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• 2005

This paper presents the development and testing of a power conditioning system(PCS) for application to a 100kW Molten Carbonate Fuel Cell(MCFC) generation system. The MCFC generation system is a part of a four year government funded research project that began in 2001. This paper presents the results of various tests and performance verification of the 100kW PCS using a DC power system that simulates the DC output of the MCFC fuel cell. Performance of the DC/DC, DC/AC converters were verified, and basic control functions such as grid connection, protection and characteristics of each components were tested. The tests were performed under light load and rated load conditions to verify the operation efficiency, power quality effects, and stability of the PCS.

• Journal of the korean Society of Automotive Engineers
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• v.3 no.2
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• pp.18-26
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• 1981

The purpose of this paper is to study the possibility of practical use of gasoline-methanol mixed fuel as an alternative fuel of gasoline engines in the light of engine performances and harmful exhaust emissions as well as mixings and separations of the mixed fuels. When the methanol of 99.8% purity is mixed with super or regular gasoline available on the market today, the experimental results obtained without modifying carburetor in this study are as follows; 1.The separation ratio depends upon the gasoline-methanol mixing ratio only, regardless of fuel temperature and fuel additives for preventing separation of phase. 2.The critical absorption ratio is affected by the gasoline-methanol mixing ratio, its temperature and the quantity of fuel additives. 3.Concerning the distillation temperature, the initial point of all sorts of fuels is almost same,but 10% point and 35-60% point of mixed fuels are lower than those of gasoline only. 4.In case of throttle valve opening set, engine output using the mixed fuels is decreased compared to gasoline, but thermal efficiency is increased as a consequence of decreasing specific energy consumption. 5.In case of fixed load test, thermal efficiency is increased at low engine speed even under low part-load as well as under comparatively high part-load including full load. 6.CO and NOx emissions are reduced remarkably with the mixed fuels.

• Journal of Electrical Engineering and Technology
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• v.10 no.5
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• pp.2031-2039
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• 2015

In the LED lighting industry, the dimming function in the LED lamp is required by demands of many consumers. To drive this LED lighting, various types of power converters have been applied. Among them, an LLC resonant converter could be applied for high power LED lighting because of its high efficiency and high power density, etc. The function of power factor correction (PFC) might be added to it. In this paper, a dimmable single-stage asymmetrical LLC resonant converter is proposed. The proposed converter performs both input-current harmonics reduction and PFC using the discontinuous conduction mode (DCM). Also, the lower voltage stress across switching devices as well as the zero voltage switching (ZVS) in switching devices is realized by the proposed topology. It can reduce cost and has high efficiency of the driver. In addition, the regulation of the output power by variable switching frequency can vary the brightness of a light. In the proposed converter, one of the attractive advantages doesn’t need any extra control circuits for the dimming function. To verify the performance of the proposed converter, simulation and experimental results from a 300W prototype are provided.

• Journal of international Conference on Electrical Machines and Systems
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• v.3 no.3
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• pp.256-263
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• 2014

Torque ripple is a very essential index for evaluating the effectiveness of a switched reluctance motor (SRM). Many common design strategies for reducing torque ripples of a SRM are changing the excitation trigger angle of stator windings, delaying the cut-off time of winding excitation, adjusting the ratio of arc angle between stator and rotor, and changing the geometric shape of rotor. However, the output torque or the efficiency of the SRM may drop as the above design strategies are solely adopted. In this paper, a hybrid design model which is obtained by the Taguchi Method for optimally designing a SRM with lower torque ripple and higher efficiency is presented. A 12S/8P motor is taken as a study case, and the 3D finite element method (FEM) is applied to analyze the characteristics of the motor and optimize the design process. The results have shown that the proposed method can achieve the design goal of obtaining a high-performance SRM for light electric vehicle applications.