• Journal of Advanced Marine Engineering and Technology
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• v.39 no.8
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• pp.833-837
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• 2015

Li-air batteries have a promising future for because of their high energy density, which could theoretically be equal to that of gasoline. However, substantial Li-air cell performance limitations exist, which are related to the air cathode. The cell discharge products are deposited on the surfaces of the porous carbon materials in the air electrode, which blocks oxygen from diffusing to the reaction sites. Hence, the real capacity of a Li-air battery is determined by the carbon air electrode, especially by the pore volume available for the deposition of the discharged products. In this study, a simple and fast method is reported for the large-scale synthesis of carbon nanoballs (CNBs) consisting of a highly mesoporous structure for Li-air battery cathodes. The CNBs were synthesized by the solution plasma process from benzene solution, without the need for a graphite electrode for carbon growth. The CNBs so formed were then annealed to improve their electrical conductivity. Structural characterization revealed that the CNBs exhibited both an pore structure and high conductivity.

• Proceedings of the KIPE Conference
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• 2003.11a
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• pp.193-196
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• 2003

For a power source of usual electronic devices such as PDA, smart phone, UPS and electric vehicle, the battery made of serially connected multiple cells is generally used. In this case, if there are some unbalanced among cell voltages, the total lifetime and the total capacity of the battery are limited to a lower value. To maintain a balanced condition in cells, an effective method of regulating the cell voltage in indispensable. In this paper introduced a method for battery balancing system using dissipation in the resistance.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.11 no.9
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• pp.727-732
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• 1998

Ag-deposited graphite powder was prepared by a chemical reduction method of metal particles onto graphite powder. X-ray diffraction observation of Ag-deposited graphite powder revealed that silver existed in a metallic state, but not in an oxidized one. From SEM measurement, ultrafine silver particles were highly dispersed on the surface of graphite particles. Cylindrical lithium ion secondary battery was manufactured using Ag-deposited graphite anodes and $LiCoO_2$ cathodes. The cycleability of lithium ion secondary battery using Ag-deposited graphite anodes was superior to that of original graphite powder. The improved cycleability may be due to both the reduction of electric resistance between electrodes and the highly durable Ag-graphite anode.

• Journal of Institute of Control, Robotics and Systems
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• v.12 no.12
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• pp.1249-1255
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• 2006

This paper presents a constant power control logic for perfect starting a microtubine in vehicle. Under extremely low temperature, performance of the start-up system is severely dropped than that of room temperature because of increasing of load of mechanical parts including engine core and drop of the lead-acid battery capacity. Unfortunately, performance drop of lead-acid battery makes severe problems that cause a malfunction of fuel and lubrication system and power fail of digital devices. So we propose the new start-up logic by constant output power control of lead-acid battery using PWM inverter controller for preventing above problems and keeping good performance of start-up system for microturbine. Also, we prove usefulness of new start-up logic through experimental results under $-32^{\circ}C$ ambient temperature.

• The Transactions of the Korean Institute of Electrical Engineers B
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• v.54 no.8
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• pp.387-394
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• 2005

This paper deals with the grid-interactive small battery energy storage system, which aims at the integration o( power quality improvement and demand side management. The main purpose of the proposed system is to achieve the peak power cutting and to compensate the current harmonics and reactive power at the point of installation on power distribution for residential homes. paper deals with the grid-interactive small battery energy storage system, In this paper, the basic principle and control algorithm is analyzed, theoretically and the design methodology of the system is discussed. To verify the proposed system, a comprehensive evaluation with theoretical analysis, simulation and experimental results for 1 KVA load capacity is presented.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.60 no.7
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• pp.1331-1338
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• 2011

This paper proposes a method for frequency control of islanded microgrid with battery energy storage system. For frequency control of islanded microgrid, battery energy storage system uses a phase locked loop algorithm with positive sequence components for a fast frequency estimation. Microgrid is a power system with small inertia because it has small capacity generators and inverter systems for renewable energy. So, Islanded microgrid's frequency varies fast and large as small generation and load changes. To reduce frequency variation of islanded microgrid, it needs a device with fast frequency response. For fast frequency response, a fast frequency tracking is important. To show the validation of proposed fast frequency tracking algorithm, battery energy storage system with proposed algorithm is tested in microgrid pilot plant.

• Proceedings of the KIPE Conference
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• 2001.07a
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• pp.81-84
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• 2001

In the power system of a satellite, solar array and a battery have directly impact on the life time of the satellite, and their stable operation is decided by whether their states are in the steady state operation or not. In this study, solar array capacity and battery characteristics of proposed communication satellite are designed and simulation is conducted according to the operation mode. Each operation mode is classified as the normal and worst case modes, respectively. The normal mode is analyzed under daylight and the eclipse with the EHT burn, and the worst case modes which have solar cell circuit failure, and battery cell failure are analyzed too.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.30 no.1
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• pp.21-27
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• 2016

The study concerning about the grid connection of the large-capacity battery energy storage system(BESS) is increasing. However, the protection study which is necessary to maintain the reliability of distribution system has been hardly performed. Therefore, this paper analyzes the effect of reclosing among protection issues in distribution system with BESS and proposes the new relcosing method. To verify the proposed method, the BESS, distribution system, and proposed method are modeled by using EMTP/ATPDraw and the various simulations according to the fault clearing time are performed. The simulation results show that the reclosing in distribution system with BESS is successfully performed by proposed method and the operation of BESS is not affected from reclosing.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.29 no.2
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• pp.47-53
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• 2015

The study concerning about the grid connection of the large-capacity energy storage system(ESS) is increasing. However, the transient study such as lightning or switching surge necessarily occurred at power system with ESS has been hardly performed. Therefore, this paper performs the analysis of lightning surge in distribution system with ESS using electromagnetic transient program(EMTP). The battery model in Matlab/Simulink is modeled by EMTP, which is the specialized software for power system transient study. Also, the bi-directional power electronics for interconnection of the battery and distribution system are modeled by EMTP. When the lightning is occurred at interconnection point of ESS, this paper simulates the existence of ESS and operation conditions of ESS and analyzes the surge in distribution system and ESS according to the various conditions.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2004.07b
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• pp.1083-1088
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• 2004

Zinc air batteries obtain their energy density advantage over the other batteries by utilizing ambient oxygen as the cathode materials, and reusing cathode as recycled form. And specific capacity of zinc powder is as high as 820mAh/g. Our research team succeeded in producing 2.4 Ah class zinc air battery for cellular phone application. In this paper we had studied performance of cathode according to various factors and demonstrated the performance of 2.4 Ah class zinc air battery for cellular phone application.