• Journal of the Korean Electrochemical Society
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• v.2 no.4
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• pp.218-220
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• 1999

The performance of the Electric Vehicle and Hybrid Electric Vehicle depends on that of the battery pack composed of series connected batteries. And thermal property is one of the main factors which decide the performance of the battery pack. So heat generation rate from the battery under the various driving mode must be measured as precise as possible because thermal characteristics of the battery affect the driving performance and battery pack's life cycle. Besides, to design and develop the battery thermal management system for the EV and HEV, the measurements of the thermal properties of the batteries are needed. However, the established calorimeter is not adequate to test an EV's battery because its cavity is too small to accommodate the EV's battery. Therefore we developed the calorimeter to test the thermal property of the EV's battery. Its cavity size is 120mm long, 75mm wide and 200mm high. The calorimeter is calibrated by the dummy cell which generates the heat rate from zero to 200W. The measuring accuracy of the calorimeter is within $2\%$ and its voltage stability is 2.5mV in the constant temperature bath.

• 한국전기화학회:학술대회논문집
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• 2001.04a
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• pp.31-31
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• 2001

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.15 no.5
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• pp.55-60
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• 2001

Most of the battery charger for electric powered forklift truck are controlled by the method of 3-phased constant current and constant voltage controls. However, these chargers have several disadvantages like a large charger capacity, and a short battery life time. To eliminate the weak points, a digital type battery charger based on multi-mode control adding a constant power control and several assistant controls in the conventional control is presented. The whole control system is performed by a low cost 8 bit one-chip micro-controller and completely digitize. So, we can get a high precision control and a good reliability.

• Proceedings of the KIEE Conference
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• 1998.11c
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• pp.822-824
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• 1998

The lithium polymer battery with polymer electrolyte is expected as a safe and long cycle life battery. This paper reports primarily the recent development results of a solid polymer electrolyte, which is a key point of the secondary battery system. The new type of polymer electrolyte was prepared under a dry Ar atmosphere by dissolving $LiCIO_4$ in a matrix of EC, PC and then dispersing polyacrylonitrile(PAN). Also adding some inorganic filler $Al_2O_3$. The dispersed solution heated at $120^{\circ}C$. The polymer electrolyte were characterized by EIS(Electrochemical Impedance Spectroscopy), TGA(Thermo Gravimetric analysis), DMA(Dynamic Mechanical Analyzer), DSC (Differential Scanning Calorimetry). The lithium ion yield is 0.29 when PAN-$Al_2O_3$ which was applied DC 5mV. The ionic conductivity of PAN, PAN-$Al_2O_3$ polymer electrolytes were showed $1.0{\times}10^{-4}S/cm$, $8.4{\times}10^{-4}S/cm$ at room temperature. When inorganic filler was added in the polymer electrolyte, ionic conductivity and lithium yield more larger than without inorganic filler.

• Transactions of the Korean hydrogen and new energy society
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• v.22 no.4
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• pp.495-503
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• 2011

The sealed nickel-metal hydride (Ni-MH) secondary battery are primarily used as energy storage for the HEV. But, the research on Ni-MH battery has focused on anode materials. In the present study, we investigate to improve the electrochemical characteristics of Ni-MH batteries using the surface treatment of $Ni(OH)_2$ cathode by CoOOH. Surface treated $Ni(OH)_2$ cathode showed significant improvement in the activation behavior, rate capability, charge retention, and cycle life of the batteries were significantly improved. In addition, the surface treated electrode exhibited the higher overvoltage for oxygen evolution than the untreated electrode. This phenomenon indicates that the charge efficiency can be improved by suppressing the oxygen evolution on cathode.

• Proceedings of the KIEE Conference
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• 2008.07a
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• pp.679-680
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• 2008

Most of the small wind turbines are set as the stand alone type in the area where the access to the grid is difficult and compulsorily uses the battery. Depending on the volume of the battery, securing of the space necessary, and has the shortcoming of replacing the battery periodically due to it's limited working life span. Recently, setting up in the vicinity of the city area is increasing and the trend of using the Grid inverter instead of battery is also increasing. This thesis is aiming mainly analyzing the characteristics of the output power of the Prototype Permanent Magnet Generator(PMG) and the Grid-Inverter and to verify through the theoretical study and tests. Tested the characteristics of the output power of the PMG through the stage 1-2 and at the stage 3 connected the output of the PMG to the Inverter and tested the characteristics of the Inverter. And at the stage 4, the maximum output power is confirmed by the continuous running test of the PMG.

• The Transactions of the Korean Institute of Power Electronics
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• v.3 no.4
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• pp.273-279
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• 1998

In this paper, the proposed charging system consists of step charging mode and time-sharing equalization charging mode. As $\Delta$V=O point is detected, the proposed cut-off method will selectively cut off the only battery to reach the $\Delta$V=O point, preventing serial-connected batteries from undercharging. In the start of each step, the equalization charging mode is performed to reduce the capacity difference among the batteries. Though it is added to simple circuit for selective cut-off, comparing with recently used step-charging method, this system can improve the life cycle of battery and charging efficiency, and be also very effective for preventing the batteries from overcharging and undercharging.

• Journal of Korean Society for Quality Management
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• v.48 no.1
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• pp.69-86
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• 2020

Purpose: This study aims to determine the optimal conditions for the spot welding process that mechanically connects the case of a cylindrical secondary battery and the negative tab. Methods: We use 33 factorial design to derive the optimal conditions for the spot welding process. The pulling strength, the cross-sectional area of nugget, and the shock test life are selected as response variables, which can represent the resistance welding quality. The input variables are selected as the welding time, welding voltage, and pressure, which are the controllable factors in the spot welding process. Results: The main effects of welding time and welding voltage and the interaction effect of welding time and welding voltage are significant. Conclusion: The optimal conditions for the spot welding process to mechanically join the negative electrode tab of the cylindrical secondary battery and the battery case are developed. The result shows that the pulling strength is increased by 44% compared to before improvement under optimal conditions.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1999.11a
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• pp.383-386
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• 1999

The importance of rechargeable lithium cells has been emphasized. So a large variety of materials has been discovered and evaluated for use as reversible cathodes and electroyltes. This paper examines the charge/discharge properties and the charge/discharge cycling life of Li$_2$O-P$_2$O-V$_2$O$_{5}$Li cells. In audition, DTA tests were carried out on Li$_2$O-P$_2$O-V$_2$O$_{5}$ glass. As a result the best performance was achieved when 0.3Li$_2$O-0.1P$_2$O$_{5}$-0.6V$_2$O$_{5}$Li cells was mixed with SP270. that is discharge capacity of 240mAh/g have been achieved. In addition this battery exhibited good cycling performance. Considering these results we expected utilization of the Li$_2$O-P$_2$O-V$_2$O$_{5}$ glass as a cathode material in a secondary battery.y battery.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.12 no.10
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• pp.1835-1839
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• 2008

Power management is a very important issue in portable electronic applications. Portable electronic devices require very efficient power management like LDO to increase the battery life. As the voltage variation of battery power is large in the application of cell phone, camera, laptop, automotive, industry application and so on, battery power is not directly used and LDO is used to supply the power of internal circuit. Besides, LDO can supply DC voltage that is lower than bauer voltage and constant DC voltage that is not related to largely fluctuated battery power. In the study, the power-save mode current and IR-drop characteristics are analyzed from a LDO with on-chip fabricated in 0.18-um CMOS technology.