• Proceedings of the KIEE Conference
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• 2002.11d
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• pp.106-108
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• 2002

Capacitive current switching test for circuit breaker and load breaker switch requires special attention because, after current interruption, the capacitive load contains an electrical charge and can cause dielectric restrike and re-ignition of the switching devices. therefore dielectric strength of capacitor load bank shall be able to withstand 4Vt (Vt : test voltage) and charging voltage discharged within 1 min. In this paper presents both characteristic of capacitive current switching tests and design of capacitor load bank.

• Journal of Sensor Science and Technology
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• v.21 no.5
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• pp.379-384
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• 2012

This paper presents the power source of wireless sensor node (WSN) using supercapacitors and a solar cell. Supercapacitors have high lifetime cycling compared to that of batteries. Supercapacitors are connected in series to achieve higher voltage and a voltage balancing circuit is required to ensure that no individual cell goes overvoltage. We employ an active balancing circuit that draws minimal current by using transistors. A diode is connected in series with each supercapacitor. A new balancing circuit that equalize the cells-voltage reduces energy consumption of supercapacitors. Voltage of operating WSN is applied 2.2-3.3V by DC/DC converter and supercapacitor voltage 2.2-5.1V. Maximum operating time of wireless sensor node is about 16 hours in full charging.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2001.05c
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• pp.62-65
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• 2001

The effects of accelerated UV radiation on EPDM used for a polymeric insulator were investigated by contact angle, surface voltage decay after corona charging, SEM-EDX, ATR-FTIR and XPS. EPDM occurs as loss of hydrophobicity by UV treatment, which followed by surface cracking and chalking. The surface voltage decay on UV-treated EPDM show that the shorter decay time corresponded to the treated samples with a longer UV exposure time. The surface oxygen and aluminum content were found to increase and carbon decrease, as is observed in EDX analysis. The ATR-FTIR and XPS indicated that C-C and C-H groups decreased and the highly oxidized carbon bonds such as C-O, C=O and O-C=O increase with time. Also, the effects of surface charges on hydrophobicity based on our results is discussed.

• The Transactions of the Korean Institute of Electrical Engineers
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• v.43 no.2
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• pp.206-215
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• 1994

A method for simulating general characteristics and temperature characteristics of discharging SCR of the capacitor discharge impulse magnetizer-magnetizing fixture system using SPICE is presented. This method has been developed which can aid the design, understanding and inexpensive, time-saving of magnetizing circuit. As the detailed characteristic of magnetizing circuit can be obtained, the efficient design of the magntizing circuit which produce desired magnet will be possible using our SPICE modeling. Especially, computation of the temperature rise of discharging SCR is very important since it gives some indication of thermal characteristic of discharging circuit. It is implemented on a 486 personal computer, and the modeling results are checked against experimental measures. The experimental results have been achived using 305[V] and 607[V] charging voltage, low-energy capacitor discharge impulse magnetizer-magnetizing fixture of air cleaner DC motor.

• Journal of Power Electronics
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• v.13 no.1
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• pp.31-39
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• 2013

The conventional non-isolated boost converter has some drawbacks such as poor dynamic performance and a discontinuous output current, which make it unsuitable for battery charging applications. In spite of its compactness and lightness, it is not preferred as a charger of portable electronic devices. In this paper, a non-isolated boost converter topology for Li-ion batteries suitable for fuel cell powered laptop computers is proposed and analyzed. The proposed converter has an additional inductor at the output to make a continuous output current. This feature makes it suitable for charger applications by eliminating the disadvantages of the conventional non-isolated boost converter mentioned above. A prototype of the proposed converter is built for the Li-ion battery charger of a laptop computer to prove the validity and advantages of the proposed topology.

• Journal of Electrical Engineering and information Science
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• v.2 no.6
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• pp.208-211
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• 1997

We have fabricated a single-electron-tunneling(SET) transistor with a dual gate geometry based on the SOI structure prepared by SIMOX wafers. The split-gate is the lower-gate is the lower-level gate and located ∼ 100${\AA}$ right above the inversion layer 2DEG active channel, which yields strong carrier confinement with fully controllable tunneling potential barrier. The transistor is operating at low temperatures and exhibits the single electron tunneling behavior through nano-size quantum dot. The Coulomb-Blockade oscillation is demonstrated at 15mK and its periodicity of 16.4mV in the upper-gate voltage corresponds to the formation of quantum dots with a capacity of 9.7aF. For non-linear transport regime, Coulomb-staircases are clearly observed up to four current steps in the range of 100mV drain-source bias. The I-V characteristics near the zero-bias displays typical Coulomb-gap due to one-electron charging effect.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1999.05a
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• pp.613-616
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• 1999

An active-matrix LCD using thin film transistors (TFTs)has been widely recognized as having potential for high-quality color flat-panel displays. Pixel-Design Array Simulation Tool (PDAST) was used to profoundly understand the gate signal distortion and pixel charging capability, which are the most critical limiting factors for high-quality TFT-LCDs. Since PDAST can simulate the gate data and pixel voltages of a certain pixel on TFT array at any time and at any location on an array, the effect of the new set of capacitance models on the pixel operations can be effectively analyzed, The set of models which is adopted from VLSI interconnections calculate more precise capacitance. The information obtained from this study could be utilized to design the larger area and finer image quality panel.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1998.06a
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• pp.321-324
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• 1998

Pixel-Design Array Simulation Tool(PDAST) was used to profoundly the gate signal distortion and pixel changing capability, which are the most critical limiting factors for high-quality TFT-LCDs. Since PDAST can simulate the gate, data and pixel voltages of a certain pixel on TFT array at any time and at any location on an array, the effect of the resistivity of gate line material on the pixel operations can be effectively analyzed. The gate signal delay, pixel charging ratio, level-shift of the pixel voltage were simulated with varying the resis5tivity of the gate line material. The information obtained from this study could be utilized to design the larger area and finer image quality panel.

• The Proceedings of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.8 no.6
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• pp.56-62
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• 1994

유동대전 현상을 밝히기 위해 간단한 유순환 장치에 설치된 프레스보드관(pressboard pipe)을 통하여 변압기 유를 순환시키면서 기초적인 실험을 행하였다. 특히, 측정 전극에 교류전계를 인가할 때 이것이 유동대전에 미치는 영향에 대하여 고찰하였다. 측정값은 절연유내에 분포된 전하의 분리와 완화에 기초를 둔 이론적 개념으로부터 유도된 공식에 의하여 검토되었다. 유동 대전은 외부에 교류전계를 인가하는 것에 의하여 증가하는 경향을 나타냈으며, 이는 교류전계의 전기력이 계면부근의 절연유내에 분포되어 있는 과잉전하에 영향을 준 결과로 나타난 현상임을 알 수 있었다.

• The Proceedings of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.11 no.2
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• pp.94-101
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• 1997

This paper proposes the equalizing charger of series connected batteries which are controlled by the time-sharing method. One-chip microprocessor dectcts the terminal voltage of each battery and then determines the charging time inversely proportional to the terminal voltage so that it decrease the un¬balanced capacity. This system is compact and light, therefore it can be applied to portable equipment such as charger for electric vehicle. And it's so effective as to prevent from overcharging which causes their life to shorten.