• 한국전기전자재료학회논문지
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• 제21권7호
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• pp.645-651
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• 2008

To reduce noise in high frequency and distortion of signal, the composition of $(Ca_{0.7}Sr_{0.3})(Zr_{0.97}Ti_{0.03})O_3$ and $(Ba_{0.2}Ca_{0.4}Sr_{0.4})TiO_3$ was developed. The composition was not solid solution, but mixtures of various phases composed of Ca, Sr, Zr, Ti and Ba oxides. The dielectric constant increased, the quality factor and the insulation resistance decreased with $(Ba_{0.2}Ca_{0.4}Sr_{0.4})TiO_3$ content. The composition of $0.4(Ba_{0.2}Ca_{0.4}Sr_{0.4})TiO_3$ satisfied the electric characteristics and the temperature coefficient of dielectric constant (TCC). In addition, the glass frit and $MnO_2$ also affected the electric characteristics. From the result of the best fit simulation, $MnO_2$ 0.3 mol%, the glass frit 0.6 wt% showed the insulation resistance $906{\Omega}{\cdot}F$, the quality factor 821, and the dielectric constant 92. With the selected composition, MLCC capacitors sized $4.5{\times}3.2{\times}2.5mm$ were manufactured with 105 layered of the dielectric thickness $16{\mu}m$ using Ni inner electrode, They represented the capacitance $98{\sim}102$ nF, the quality factor 1,200 and the insulation resistance $1,500{\Omega}{\cdot}F$. Also, they had high break-down voltage with $107{\sim}115V/{\mu}m$, and satisfied the SL TCC characteristics.

• 전자공학회논문지SC
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• 제41권2호
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• pp.61-68
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• 2004

전기를 이용한 치아의 자극은 치수의 생활력 평가의 한 방법이다. 전기 치수 검사의 기본원리는 치아 내의 치수에 전류 자극을 가하여 유발되는 통증 유무로 치수의 생활력을 평가한다. 그러나 치아의 에나멜질의 임피던스가 크고 개인에 따라 차이가 많기 때문에 치아의 상태에 영향을 받지 않으면서 자극을 제어하기가 불가능하다. 대부분의 치수검사기가 전압 자극 방법을 사용하고 있어 개인에 따라 자극 역치 값이 크게 변화한다 그러므로 치아 에나멜질의 두께 차에 의해 발생하는 영향을 최소화하기 위해 정 전류 치수 검사기가 필요하다. 그리고 치아 임피던스에 관계없이 넓은 전류 범위를 갖는 치수 검사기가 필요하다. 본 연구에서는 전류 안정 회로를 사용하여 최대 150 uA의 전류와 통증을 완화하는 버스트 파형을 발생시킬 수 있는 정 전류원 치수 검사기를 개발하고 그 성능을 확인하였다.

• 한국산업융합학회 논문집
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• 제23권2_1호
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• pp.115-124
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• 2020

In wireless power transfer (WPT) system, the conventional compensation topologies only can provide a constant current (CC) or constant voltage (CV) output under their resonant conditions. It is difficult to meet the CC and CV hybrid charging requirements without any other schemes. In this study, a switching hybrid topology (SHT) is proposed for CC and CV electric vehicle (EV) battery charging. By utilizing an additional capacitor and two AC switches (ACSs), a double-side LCC (DS-LCC) and an inductor and double capacitors-series (LCC-S) topologies are combined. According to the specified CC and CV charging profile, the CC and CV charging modes can be flexibly converted by the two additional ACSs. In addition, zero phase angle (ZPA) also can be achieved in both charging modes. In this method, because the operating frequency is fixed, without using PWM control, and only a small number of devices are added, it has the benefits of low-cost, easy-controllability and high efficiency. A 3.3-kW experimental prototype is configured to verify the proposed switching hybrid charger. The maximum DC efficiencies (at 3.3-kW) of the proposed SHT is 92.58%.

• 한국자동차공학회논문집
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• 제21권2호
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• pp.136-145
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• 2013

It is very important to determine specifications of components included in the drive-train of vehicles at the initial design stage. In this study, component sizing process and performance analysis for Extended-Range Electric Vehicles (E-REV) are discussed based on the foundation of determined system configuration and performance target. This process shows sizing results of an electric driving motor, a final drive gear ratio and a battery capacity for target performance including All Electric Range (AER) limit. For E-REV driving mode, the constant output power of a Gen-set (Engine+Generator) is analyzed in order to sustain State of Charge (SOC) of the battery system.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2004년도 추계학술대회 논문집
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• pp.1322-1327
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• 2004

There are some previous studies that utilize constant impedance models or constant current models for electric trains to perform the static analysis of AT feeding systems. These mentioned models have some merits of linear systems but yield erroneous results because of the innate restraints of the models since linear models cannot represent the features of constant power in inverter-driven trains. From these reasons, it is suitable that the train be considered as a constant load model when it drives or as a constant source model when it applies regenerative brake. However, excessive rise of regenerative voltage during the braking may damage the vehicle itself and the feeding systems so the voltage must be restricted below a certain value. Keeping these facts in minds, we suggest new methods of analyzing AT feeding systems using the constant power models with the conditions of voltage constraints. The simulation results from a sample system using the proposed method illustrate both the states of system variables and the supply-demand relation of power among the trains and the systems very clearly, so it is believed that the proposed method yields more accurate results than conventional methods do.

• Journal of Power Electronics
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• 제17권4호
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• pp.1109-1116
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• 2017

Wireless power transfer (WPT) technology has the advantages of intelligence and facilitation. This paper designs a WPT system applied to battery charging and provides a strategy which switches from the constant current (CC) charging mode to constant voltage (CV) charging mode. The LCL-LCL topology is used to realize the CC output, while the LCL-S (series compensation) topology is used to realize the CV output. The main factor affecting the output characteristics is extracted by analyzing the two topologies above. Based on the main factor, this paper puts forward a modified way to design the system. In addition, on-line monitors for the battery and switches are placed at receiving side, which avoids the need for introducing an information interaction module into the system. Therefore, the complexity of the controlling system is reduced. Finally, simulation and experimental analyses are carried out to verify the correctness of the compound topologies.

• 한국섬유공학회:학술대회논문집
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• 한국섬유공학회 1988년도 학술발표초록집
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• pp.34-34
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• 1988

The pyroelectricity of poly(vinylidenefluoride) films prepared by varying the draw ratio and the poling field was investigated. As the draw ratio and the electric field on poling of the drawn samples increased, so did the pyroelectric coefficient. But the effect of electric field on the pyroelectricity was greater than that of draw ratio. The pyroelectric and piezoelectric activities could be explained by the polarization using the thermally stimulated current. The relation between pyroelectric coefficient and piezoelectric stress constant showed a good linearity.

• 대한전기학회논문지
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• 제34권9호
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• pp.349-354
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• 1985

The conducting currents of polypropylene film was measured a function with electric fields at temperature of 25,35,45( C). It appears that there are four regions of conducting currents, depending upon the strength of the applied electric field` ohmic region based on ionic conduction, Poole-Frenkel region, Schottky region and negative resistance region. Several information of dielectric constant and potential barrier height were obtained.

• 약학회지
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• 제18권3호
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• pp.197-202
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• 1974

The data pf dosspcoatopm cpmstamts for aliphatic amines and quaternary ammonium-methylorange salts are based on the electrosatic theory of conductance. Dissociation constants for primary amines nad quaternary ammonium-methylorange salts (1$\times$10$^{-5}$~1$\times$10$^{-3}$ M) in nitrobenzene solution or water solution was evaluated from the relation of the concentration and the electric conduction and the electric conductance at $25^{\circ}C$ Plots of ${\delta}C$ against reciprocal conductance were linear ; hence the center-to-center distance of this salt was 1.75 $\AA$ in nitrobenzene solution.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2005년도 전력전자학술대회 논문집
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• pp.1-3
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• 2005

This paper is to evaluate practical advantage in using maximizing efficiency control strategy in induction motor drives for electric vehicles. A maximizing efficiency control strategy consist of a flux estimation with direct field oriented controller is proposed and compared with the general constant flux control strategy. The comparison is carried out by simulation.