• 전자공학회논문지A
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• 제31A권6호
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• pp.107-116
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• 1994

In this paper, The electrical properties of MOS capacitors and transistoras with gate of in-situ doped amorphous Si and poly Si doped by POCI$_3$. Under constant current F-N stress, MOS capacitors with in-situ doped amorphous Si gate have shown the best resistance to degradation in reliabilty properties such as increase of leakage current, shift of gate voltage (V$_{g}$). shift of flat band voltage (V$_{fb}$) and charge to breakdown(Q$_{bd}$). Also, MOSFETs with in-situ doped amorphous Si gate have shown to have less degradation in transistor properties such as threshold voltage, transconductance and drain current. These improvements observed in MOS devices with in-situ doped amorphous Si gate is attributed to less local thinning spots at the gate/SiO$_2$ interface, caused by the large grain size and the smoothness of the surface at the gate/SiO$_2$ interface.

• 전기화학회지
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• 제5권4호
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• pp.192-196
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• 2002

Ionic liquids based on l-ethyl-3-methylimidazolium cation $(EMI^+)$ and inorganic or organic anions containing fluorine atoms were applied to electrolyte materials for double-layer capacitors. The double-layer capacitors composed of a pair of activated carbon electrodes and an ionic liquid selected from $EMIBF_4,\; EMINbF_6,\;EMITaF_6,\;EMICF_3SO_3,\;EMI(CF_3SO_2)_2N,\;and\;EMI(C_2F_5SO_2)_2N$ showed inferior low-temperature characteristics to those of a conventional nonaqueous electrolyte based on propylene carbonate (PC) solvent. On the other hand, the capacitor using $EMIF{\cdot}2.3HF$ showed excellent low-temperature characteristics due to its high conductivity at low temperatures, however, it had a lower working voltage $(\~2V)$ than the conventional nonaqueous counterpart $(\~3V)$.

• 조명전기설비학회논문지
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• 제24권9호
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• pp.71-78
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• 2010

The existing capacitor-testers could only judge the condition of capacitor is normal or abnormal, and could not inform the real characteristics of the tested capacitors. In this research, it has designed the real-time observation of the new capacitor in charge and discharge tester for showing capacitor conditions and classification through wide voltages by regular cycle-tests. And proposed the quality classification algorithm of capacitors for more simple and practical, and approve them by test.

• Journal of Electrical Engineering and Technology
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• 제7권3호
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• pp.358-365
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• 2012

A new third harmonic injection circuit for light-emitting diode (LED) drivers is proposed to eliminate electrolytic capacitors and thereby extend the lifetime of LED drivers. When a third harmonic current is injected to the input current of the LED driver, the required capacitance of the driver can be reduced. The proposed circuit can control an injection ratio and has simple circuitry. The synchronous third harmonic is generated by a phase locked loop (PLL), a 1/3 counter, and op-amps and applied to a power factor correction circuit. Thus, the storage capacitor can install film capacitors instead of the electrolytic capacitor. The value of storage capacitance can be reduced to 78% compared to an input power factor of 100%. The proposed circuit is applied to the 80W prototype LED driver to experimentally verify the performances.

• Journal of Power Electronics
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• 제13권1호
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• pp.94-103
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• 2013

A capacitor deterioration of LCL-filter grid-connected PWM converters is progressed by the self-healing mechanism. It leads to the degradation of the filter performance and drop of power factor. Thus, it is required to diagnose fault-point of capacitors and determine the replacement time. Typically, the fault of capacitors is determined when the capacitance is reduced up to 80% from initial value. This paper proposes algorithm to the determine capacitor replacement time of an LCL filter. The algorithm takes the advantage of change of the response on the injected resonant frequency corresponding to 80% value from the initial capacitance. The results of the algorithm are demonstrated through simulations and experiments.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2018년도 전력전자학술대회
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• pp.186-188
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• 2018

In this paper, a single-phase multifunctional onboard battery charger with small DC-link capacitors is proposed, where the low-voltage battery charger is utilized as an active power filter to mitigate the inherent second-order ripple power when the high-voltage (HV) battery is charged from the grid. In this scheme, the large DC-link electrolytic capacitors of the HV battery charger can be eliminated without additional switches, leading to the reduction of cost and volume of the onboard battery charger. The validity of the proposed topology has been verified by the simulation results.

• 대한전기학회논문지:전력기술부문A
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• 제54권6호
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• pp.274-283
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• 2005

This paper presents a new method to derive energy function based on vector product. Using this method, an energy function to consider transfer conductances and capacitors is derived. Then we recommend a voltage collapse criteria to predict the voltage collapse in power systems by using the energy margin derived by the proposed energy function. This energy function is applied to a 2-bus power system reflecting transfer conductances and capacitors. We show that the energy function derived based on vector product can be applied in order to analyze power system stability and the energy margin can be utilized as a criterion of voltage collapse by simulation for the 2-bus system.

• Transactions on Electrical and Electronic Materials
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• 제8권4호
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• pp.182-187
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• 2007

The use of the pulsed electro acoustic (PEA) method allowed us to perform the direct observations of spatio-temporal charge distributions in Electric double layer capacitors (EDLCs) based on polarizable nanoporous carbonaceous electrode. The negative charge density became the maximum, about $205C/m^3$ at the region where was near to collector layer in EDLCs for case $V_{DC}=2.5V$, while the positively charged density became the maximum, about $61.1C/m^3$ at the region where it was located around the cathode layer. The performance of the best sample was found to be better in terms of the charge density (Cs) and specific energy ($E_s$) with a maximum value of ${\sim}8.4F/g$ and 26 Wh/kg. The $C_s$ obtained from the PEA method agreed well with that from the energy conversion method. The PEA measurement used here is a very useful method to quantitively investigates the spatio-temporal charge distribution in EDLCs.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2003년도 하계학술대회 논문집 A
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• pp.9-11
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• 2003

In power system planing and operation, voltage and reactive power control are very important. The voltage deviation and system losses can be reduced through control of reactive power sources. In general, there are several different reactive power sources, we used UPFC and switched shunt capacitor to improve the voltage profile and to reduce system losses in this study. Since there are many switched shunt capacitors in power system, so it is necessary to coordinate these switched shunt capacitors. In this study, Genetic Algorithm(GA) is used to find optimal coordination of UPFC and switched shunt capacitors in a local area of power system. In case study, the effectiveness of the proposed method is demonstrated in KEPCO's power system. The simulation is performed by PSS/E.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2001년도 하계종합학술대회 논문집(5)
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• pp.241-244
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• 2001

This paper proposes a nonlinear impedance circuit composed by diodes and inductors or capacitors. This circuit needs no control circuits and switches, and the impedance value is changed by the polarity of current or voltage, This paper presents one of these applications to improve the input current of capacitor input diode rectifiers. The rectifier using the nonlinear impedance circuit id constructed with four diodes and four capacitors in addition to the conventional rectifiers, that is it has eight diodes and five capacitors, including a DC link capacitor. It makes harmonic components of the input current reduce and the power factor improve. A circuit design method is shown by experimentation and confirmed simulation. It explained that compared conventional pulse-width modulated (PWM)inverter with half pulse-width modulated (HPWM) inverter. Proposed HPWM inverter eliminated dead-time by lowering switching loss and holding over-shooting.