• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2017.05a
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• pp.275-278
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• 2017

The automotive society is facing many challenges in minimizing the energy loss to improve performance and fuel economy of the vehicle. This work "Implement of Power Density for AC Generator Using a Fill Factor of Slot" is a research in Electrical Generator design, to improve power density of Alternator used in conventional IC engine powered vehicles. The power density of the alternator directly influences the fuel economy and performance in the motor vehicle. The size and weight of the alternator can be reduced by suitably designing power density of alternator. The simulation model of alternator is made and tested for different stator space factor using solid and round conductor to demonstrate the improvement in the output performance and efficiency. The result shows that there is an average 10% improvement in efficiency of alternator by using the solid conductor. The energy balance of the system also increased SOC in the base model.

• Applied Chemistry for Engineering
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• v.10 no.3
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• pp.415-418
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• 1999

The characteristics of VRLA (valve regulated Iead-acid) battery with the tubular positive plate and gel type electrolyte were examined as a function of active material filling density. The filling density of positive plate was 3.2 g/mL, 3.4 g/mL, and 3.6 g/mL, respectively. These VRLA batteries were cycled with 100% DOD (depth of discharge) at the $C_5/5$ rate, followed by IU-type recharge with $I_{max}=0.2C_{10}/10$ and a final voltage V=2.40 V/cell. The test was performed in a thermostatic room at $25{\pm}1^{\circ}C$. The result indicated that the initial capacity was independent of active material filling density, i.e., the highest initial capacity was 3.4 g/mL of filling density and the lowest was 3.6 g/mL. On aspect of the cycle-life performance of the VRLA battery, the filling density of 3.6 g/mL was similar to that of 3.4 g/mL in the positive plate, and both were higher than that of 3.2 g/mL. Water-loss and degradation of the VRLA battery were decreased according to an increase of the filling density in the positive plate. The optimum filling density of the active material was 3.4~3.6 g/mL.

• Applied Chemistry for Engineering
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• v.10 no.6
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• pp.814-821
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• 1999

The specific capacitance characteristics of the electric double layer capacitors(ELDC) which were made of phenol based activated carbon fiber(ACF) electrodes. Also the effect of aqueous electrolytes on the cell performance has been investigated with respect to different specific surface areas of electrodes and different kinds of aqueous electrolytes. It has been shown that larger surface area and pore size, higher conductivity of electrodes, and higher ion mobility of electrolytes have better specific capacitances. It has been found that heat treatment at $1200^{\circ}C$ and $CO_2$ post-activation at $900^{\circ}C$ of the electrode are effective to improve the specific capacitance over 145F/g and 165F/g, respectively. The EDLC showed high efficiency and long cycle life over 30000 cycles.

• Proceedings of the KIPE Conference
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• 2016.07a
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• pp.311-312
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• 2016

본 논문에서는 사이즈가 다른 고출력 원통형 리튬이온 배터리의 Remaining Useful Life(RUL)을 방전용량 기반으로 전기적 특성분석을 실시하였다. 우선, 배터리의 충/방전이 계속될 시 용량이 어떻게 변화하는지 실험해보았으며, 만충 전압(Fully Charged)에서 만방 전압(Fully Discharged) 까지의 각각의 State-Of-Charge(SOC)에서 Hybrid Pulse Power Characterization (HPPC) Test를 이용해 충전 저항과 방전 저항을 구하여, 용량과 저항의 관계를 파악하였으며, 배터리 RUL을 알기 위한 기본 정보를 확보했다.

• Journal of the Korean Electrochemical Society
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• v.19 no.1
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• pp.21-27
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• 2016

Vanadium redox flow batteries (VRFBs) using the electrolytes containing various vanadium ions in sulfuric acid as supporting solution are one of the energy storage devices in alternatively charging and discharging operation modes. The positive electrolyte contains $V^{5+}/V^{4+}$ and the negative electrolyte $V^{2+}/V^{3+}$ depending on the operation mode. To prevent the mixing of two solutions, proton exchange membranes are mainly used in VRFBs. Nafion 117 could be the most promising candidate due to the strong oxidative property of $V^{5+}$ ion, but causes high crossover of electroactive species to result in a decrease in coulombic efficiency. In this study, the composite membranes using Nafion ionomer and porous polyethylene substrate were prepared to keep good chemical stability and to decrease the cost of membranes, and were compared to the properties and performance of the commercially available electrolyte membrane, Nafion 117. As a result, the water uptake and ionic conductivity of the composite membranes increased as the thickness of the composite membranes increased, but those of Nafion 117 slightly decreased. The permeability of vanadium ions for the composite membranes significantly decreased compared to that for Nafion 117. In a single cell test for the composite membranes, the voltage efficiency decreased and the coulombic efficiency increased, finally resulting in the similar energy efficiency. In conclusion, the less cost of the composite membranes by decreasing 6.4 wt.% of the amount of perfluorinated sulfonic acid polymer due to the introduction of porous substrate and lower vanadium ion permeability to decrease self-discharge were achieved than Nafion 117.

• Proceedings of the Korean Information Science Society Conference
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• 2007.10b
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• pp.238-242
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• 2007

일반적인 휴대용 기기와 마찬가지로 모바일 피씨(Mobile PC, laptop)에서도 배터리(Battery)는 빼놓을 수 없는 부분으로 이에 대한 테스트는 매우 중요하다. 배터리에 대한 테스트는 모바일 피씨 개발 시 충전과 방전을 수백 회를 반복하여 수행을 하게 되고, 이 배터리 테스트에 상당한 시간이 걸리게 된다. 컴퓨터 관련 부품의 빠른 발전과 함께 모바일 피씨에 대한 사용자들의 다양한 요구에 의해 모바일 피씨의 종류가 다양하게 분화되고, 또한 개발 기간이 짧아지는 추세에 있다. 이에 따라 많은 시간을 요구하는 배터리 테스트에 대한 개선을 위한 노력이 행하여져 왔다. 본 논문에서는 이러한 개선 사항에 대하여 알아보고, 이를 바탕으로 추가적인 개선점을 제시하고 그에 대한 시스템을 구현하고자 한다.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.28 no.5
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• pp.191-198
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• 2018

SnSb alloy powders with excess Sn or Sb are fabricated by the high energy ball-milling of pure Sn and Sb powders with different Sn/Sb molar ratios, and then their material properties and lithium electrochemical performances are investigated. It is revealed by X-ray diffraction that SnSb alloys are successfully synthesized, and the powder size is decreased via ball-milling. Charge-discharge test using a coin-cell shows that the best result, in terms of the cyclability and the capacity after 50 cycles, comes from the electrode composed of Sn : Sb = 4 : 6, i.e. the capacity of $580mAh\;g^{-1}$ after 50 cycles. When the electrode is composed of Sn : Sb = 3 : 7, however, the capacity is noticeably decreased by the restrained Sn reaction with Li-ion. The pure SnSb alloy powders (Sn : Sb = 5 : 5) results in the second best performance. In the case of Sn-rich SnSb alloys, the initial capacity is relatively high, but the capacity is quickly fading after 20 cycles.

• Proceedings of the KIPE Conference
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• 1998.07a
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• pp.433-437
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• 1998

Equalize SOC of the cell which effect on the charge.discharge ability and the efficiency of the battery, through the charge.discharge characteristic test of the battery source, and develope the high efficiency charge.discharge system in the series HEV have a constant engine-generator output. For this, in this paper, establish the electrical model and the condition of high efficiency charge.discharge, and proposed the improvement method of charge.discharge characteristic in the battery source that consist of twenty Ni-MH cells connected serial/parallel

• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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• 2005.11a
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• pp.363-365
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• 2005

It describes a design analysis and test results of an energy transfer system which consists of two 0.5 MJ superconducting coil and three Inverter-Converter Bridges(hereinafter called ICB). A point of design is to satisfy the required stored energy capacity rather than magnetic field density with minimum energy transfer time using the calculation results of state-space averaging methods instead of Fourier series. It is proven that the considered methods are effectively through system experiments.

• Proceedings of the KIPE Conference
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• 2013.07a
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• pp.169-170
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• 2013

One important test for formation and grading of the lithium-ion battery is to confirm the performance of the battery while discharging battery down to zero volts. In this paper, a novel charge/discharge converter with zero-voltage discharge function is proposed. The proposed converter is able to discharge the battery until the voltage reaches to zero volts. The phase-shifted full bridge method is used to charge the battery and the current-fed push-pull method with bidirectional switches is used for the discharge. The ZVS turn-on is achieved in the charge operation and the ZVS turn-off in the discharge operation. The performance of the system is verified by the experiments using lithium-ion batteries.