• Transactions on Electrical and Electronic Materials
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• 제6권3호
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• pp.97-100
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• 2005

Dynamic response of organic light-emitting diodes were analyzed in $ITO/Alq_3$(100 nm)/Al device structure with a variation of voltage an frequency. At low frequency region, complex impedance is mostly governed by resistive component, and at high frequency region by capacitive component. Also, we have evaluated resistance, capacitance and permittivity of devices.

• 대한전자공학회논문지
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• 제6권1호
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• pp.19-22
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• 1969

하이브리드-π 등가회로를 사용하여 공통 에미터 트랜지스타를 궤환소자로 하는 대수증폭기의 전달함수와 안정에 필요한 입력용량 C1의 최소치를 유도하였다.

• 한국안전학회지
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• 제8권4호
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• pp.95-100
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• 1993

In power transistor switching circuit have shunt snubber(dv/dt limiting capacitor) and series snubber (di/dt limiting inductor). The shunt snubber is used to reduce the turn-off switching loss and the series snubber is used to reduce the turn-on switching loss. Design procedures are derived for selecting the capacitance, inductor and resistance to limit the peak voltage and current values. The action of snubber is analyzed and applied to the design for safety PWM inverter.

• 한국표면공학회지
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• 제26권4호
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• pp.163-174
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• 1993

The effect of gelatine on the electrodeposition of copper in cupric sulfate-sulfuric acid solution was investi-gated using an ac impedance technique. In the presence of gelatine, the charge transfer resistance was in-creased and the electrical double layer capacitance was decreased. A model was suggested to explain the im-pedance spectra and it fitted well the experimental data. Also the uniformity of deposit thickness was in-creased while the grain size was decreased by the addition of gelatine.

• 대한화학회지
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• 제40권1호
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• pp.37-43
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• 1996

텅스텐을 작업 전극으로 사용하여 순환 전압-전류법으로 합성한 폴리아닐린 막의 전기화학적 임피던스를 0.1M 황산 용액에서 측정하였다. 전기 전도성을 갖는 퍼텐셜 영역에서는 고분자 막의 큰 축전-용량과작은 저항이 직렬로 연결된 전기화학 쎌이 관측되었다. 순수한 텅스텐에 입혀진 폴리아닐린은 접촉 저항을 무시할 수 있었으나, 산화 전극 막이 입혀진 텅스텐의 경우는 산화 전극 막의 저항과 접촉 저항이 관측되었다. 측정된 임피던스 데이터로부터 전극의 등가 회로를 추정하였으며, 이 등가 회로를 토대로 하여 폴리아닐린-막 안에 혼입된 이온의 물질 이동 파라미터를 산출하였다.

• 전기학회논문지
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• 제57권12호
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• pp.2276-2280
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• 2008

In this paper, we present thermal dependancy of LED package element by changing temperature of MCPCB for design high efficiency LED lamp, and confirmed influence of LED chip against temperature with analysis of thermal resistance and thermal capacitance. As increasing temperature, WPOs were decreased from 25 to 22.5 [%] and optical power were also decreased. that is decreased reason of optical power that forward voltage was declined by decrease of energy bandgap. Therefore optical power by temperature of MCPCB should consider to design lamp for street light and security light. Moreover, compensation from declined optical efficiency is demanded when LED package is composed. Also, thermal resistances from chip to metal PCB were decreased from 12.18 to 10.8[$^{\circ}C/W$] by changing temperature. Among the thermal resistances, the thermal resistance form chip to die attachment was decreased from 2.87 to 2.5[$^{\circ}C/W$] and was decreased 0.72[$^{\circ}C/W$] in Heat Slug by chaning temperature. Therefore, because of thermal resistance gap in chip and heat slug, reliability and endurance of high power LED affect by increasing non-radiative recombination in chip from heat.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2000년도 하계종합학술대회 논문집(2)
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• pp.36-39
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• 2000

The adaptive learning circuit is designed the basis of modeling of MFSFET (Metal-Ferroelectric-Semiconductor FET) and the numerical results is analyzed. The output frequency of the adaptive learning circuit is inversely proportioned to the source-drain resistance of MFSFET and the capacitance of the circuit. The output frequency modulation of the adaptive learning circuit is investigated by analyzing the source-drain resistance of MFSFET as functions of imput pulse numbers in the adaptive learning circuit and the dimensionality factor of the ferroelectric thin film. From the results, the frequency modulation characteristics of the adaptive learning circuit, that is, adaptive learning characteristics which means a gradual frequency change of output pulse with the progress of input pulse are confirmed.

• 전기학회논문지P
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• 제58권2호
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• pp.207-213
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• 2009

Electrolytic capacitors have been widely used in power electronics system because of the features of large capacitance, small size, high-voltage, and low-cost. Electrolytic capacitors, which is most of the time affected by aging effect, plays a very important role for the power electronics system quality and reliability. Therefore it is important to estimate the parameter of an electrolytic capacitor to predict the failure. This paper proposed a novel fault diagnosis method of an electrolytic capacitor used for voltage smoothing in boost DC converter. The equivalent series resistance(ESR) of electrolytic capacitor estimated from FFT result of filtered waveform of capacitor voltage/current. Main advantage of the proposed method include circuit simplicity and easy implementation. Simulation and experimental results are shown to verify the performance of the proposed method.

• 한국조명전기설비학회:학술대회논문집
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• 한국조명전기설비학회 2004년도 학술대회 논문집
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• pp.3-7
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• 2004

An electric power efficiency of electrodeless fluorescent lamp has big relativie property of gas in lamp, gas pressure, lamp formation, ingredients of magnetic substance and shape and action frequency etc. We used magnetic substance that open self-examination material of electrodeless fluorescent lamp antenna. Ferrite that is used in this experiment was Mn-Zn type. We have examined resistance kind, impedance, Q-factor's frequency characteristic by ferrite. Impedance, resistance and capacitance did not show difference in start frequency 2.65 [MHz] but there was difference quantity. We could know Q-factor's difference according to material, and Q-factor's is important part of antenna design.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 1996년도 춘계학술대회 논문집
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• pp.635-640
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• 1996

A thermo-elastic system in the production machine has highly nonlinear dynamic characteristics. In general, the finite element method is utilized for accurate analysis. However, it requires large computing time. Thus, thermo-elastic systems are usuallymodeled as electric and fluid system using lumped para,eter. In this paper. we propose the bondgraph model and transient simulation methodology of thermo-elastic system in consideration of various boundary and joint contact conditions. Consequently, the proposed method ensures a possibility of its on-line compensation about undesirable phenomena by using real time estimate process and electronic cooling device for thermal appropriate behavior. Thermo-elastic model consisting of bush and shaft including contact condition is presented.