• Proceedings of the KIEE Conference
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• 2008.07a
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• pp.1663-1664
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• 2008

Many years ago, most of thermal power plants built in this country were of subcritical pressure, of medium or small size, of constant pressure operations and of drum type steam generators with circulation type boilers. But, nowadays almost all of them were of high efficiency, of supercritical pressure, of big capacity, of sliding pressure operations, and of once through type steam generators. Presently built once through boilers introduce turbine bypass systems to variable pressure operation which eliminates unexpected materials in boiler tube during startup, minimizes fuel loss by short startup period and eventually improve both total efficiency and power system stability.

• Proceedings of the KIEE Conference
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• 2009.07a
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• pp.1664_1665
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• 2009

Many years ago, most of thermal power plants built in this country were of subcritical pressure, of medium or small size, of constant pressure operations and of drum type steam generators with circulation type boilers. But, nowadays almost all of them were of high efficiency, of supercritical pressure, of big capacity, of sliding pressure operations, and of once through type steam generator. It has such advantage as the reduction of startup duration, but it control system and operation method are very complicated. It has a big difference in operation method of turbine and boiler. The feedforward control needs to be introduced to prevent such problems as thermal shock during the transit from normal operation into bypass operation. This paper introduces the turbine control and turbine bypass control during startup of thermal power plants.

• Proceedings of the KIEE Conference
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• 2007.11a
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• pp.81-82
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• 2007

열처리 조건이 이종접합 유기태양전지(heterojunction organic photovoitaics)의 power conversion efficiency(PCE)에 미치는 영향에 대해 살펴보았다. 본 연구에서는 열처리 온도와 열처리 시간을 변수로 다양한 조건하에서 유기태양전지를 제작하고 AM1.5G 조건에서의 효율 변화를 관찰하였다. 열처리 온도는 $90^{\circ}C$, 열처리 시간은 20분에서 가장 우수한 변환효율이 관찰되었다.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1999.11a
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• pp.129-131
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• 1999

Driving generator of USMs(ultrasonic motors) with low noise, high efficiency was designed and fabricated. It was focused on merits such as size-reduction, thermal resistance, To control revolution speed, input frequency was varied. Output of generator had frequency range of 39.1 ∼ 43.5 MHz and voltage of 120 V. USM with resonant frequency 40.3 kHz exhibited a maximum torque of 2.5 kg $.$ cm and a maximum revolution speed of about 130 rpm.

• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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• 2007.05a
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• pp.152-156
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• 2007

We introduce the IP3102 which is developed by Interpion Semiconductor co. LTD. for the CFL ballaster. The IP3102 has thermal compensation function. In this paper, we present the temperature compensation design technique and its implementation in the IP3102. The experimental results is also presented in this paper.

• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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• 2009.05a
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• pp.157-159
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• 2009

LED BLU(Back Light Unit), based on MCPCB(Metal Core Printed Circuit Board) with anodizing oxide dielectric layer and improved thermal dissipation property, are presented. Reflecting cups were also formed on the surface of the MCPCB such that optical coupling between neighboring chips were minimized for improving the photon extraction efficiency. LED chips were directly attached on the MCPCB by using the COB (Chip On Board) scheme.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 2002.10a
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• pp.99-103
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• 2002

A field test was peformed to estimate the thermal performance of the forced convection electric air heater by the experiment. Air temperature, flow rate and electrical power input were measured with the related measurement sensors, and acquisition methods for the measured data were studied to effectively estimate the thermal performance of the tested air heater. To determine the mean air temperature at the flow cross-section, measuring positions were chosen by considering the flow velocity profile and the equally divided cross-sectional area. From the experimental results, thermal efficiency is obtained as an indication of the tested electric air heater performance.

• Journal of the Korean Vacuum Society
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• v.21 no.4
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• pp.185-192
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• 2012

p-n junction temperature and thermal resistance of Light Emitting Diode (LED) package are affected by the chip size due to the change of the thermal density and the external quantum efficiency considering the heat dissipation through conduction. In this study, forward voltage was measured for two different size LED chips, 24 mil and 40 mil, which consist constitute 16-chip package. p-n junction temperature and thermal resistance were determined by thermal transient analysis, which were discussed in connection with the electrical characteristics of the LED chip and the structure of the LED package.

• Proceedings of the KIPE Conference
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• 2002.11a
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• pp.89-93
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• 2002

Hydrogen - Oxygen gas has obtained from water electrolysis reaction. It is mixed gas havingconstant volume ratio 2:1 Hydrogen and Oxygen, and it is used as a source of thermal energy by combustion reaction. This gas has betterristics in the field of economy, efficiency of energy, and environmental intimacy than used both of acetylene gas and LPG for gas welding machin. So nowdays many studies of Water-Electrolyzed gas are progressed, and commercially used as a source of thermal energy for gas welding In the industry. For Water-Electrolyzed Source, it was used diode rectifier or SCR rectifier for get DC source. This method which is not looking to improve a source for impossible current control or voltage and limited control intervals. In this paper, it was relized and designed in source of pulse type for complementing existing-DC source type, also by experiment it was acquired producting characteristics of Hydrogen -Oxygen Gas through feature of source

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.23 no.12
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• pp.996-1001
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• 2010

Recently, the demand of ceramic metal halide lamp has been expanded. Therefore, the lamp with high efficiency and long lifetime are increasing and the evaluation of reliability is needed. In this paper, the degradation phenomena of ceramic metal halide lamp was studied. The lamp was tested for 3000 on/off cycles with each cycle having a duration of 20 minutes on and 20 minutes off based on the accelerated aging experiment based on "Reliability Standards RS C 0085". As result, the corrosion of arc tube and leak was appeared from reaction between inner wall of PCA and chemical elements, and distortion of electrode was resulted from difference of thermal expansion between arc tube of PCA and electrode. Also, the efficiency of lamp was decreased by the change of inner pressure, operation temperature, and driving voltage from wall blackening.