• Proceedings of the KIEE Conference
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• 1997.07d
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• pp.1600-1602
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• 1997

We have studied microstructure of carbn fiber and graphite using scanning electron microscope, x-ray diffractommetry and x-ray photoelectron spectroscopy. According to the results, intercalation of lithium ion affected formation of film on carbon surface and changed structural parameter. Also, we found that film on carbon surface included lithium ion. And, the results of XPS indicated that surface of lithiated carbon materials existed P and F consisting electrolyte. Thus, We expected electrolyte cointercalated with lithium.

• Journal of Magnetics
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• v.18 no.4
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• pp.473-480
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• 2013

A new concept design of electromagnetic energy harvester is proposed for powering a tire pressure monitoring sensor (TPMS). The thin coil strap is attached on the circumferential surface of a rim and a permanent magnet is placed on the brake caliper system. When the wheel rotates, the relative motion between the magnet and the coil generates electrical energy by electromagnetic induction. The generated energy is stored in a storage unit (rechargeable battery, capacitor) and used for TPMS operation and wireless signal transmission. Innovative layered design of the strap is provided for maximizing energy generation. Finite Element Method (FEM) and experiment results on the proposed design are compared to validate the proposed design; further, the method for design improvement is discussed. The proposed design is excellent in terms of durability and sustainability because it utilizes the everlasting rotary motion throughout the vehicle life and does not require material deformation.

• Bulletin of the Korean Chemical Society
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• v.31 no.11
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• pp.3190-3194
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• 2010

Mixed electrolytes formed by the combination of 1-butyl-1-methylpyrrolidinium bis(trifluoromethanesulfonyl) imide (BMP-TFSI) ionic liquid and standard liquid electrolyte are prepared and characterized. Linear sweep voltammetry measurements demonstrate that these mixed systems exhibit a wide electrochemical stability window, allowing them to be suitable electrolyte for carbonaceous anode-based lithium-ion batteries. Lithium-ion cells composed of graphite anode and $LiCoO_2$ cathode are assembled using the mixed electrolytes, and their cycling performances are evaluated. The cell containing proper content of BMP-TFSI shows good cycling performance comparable to that of a cell assembled with organic electrolyte. The presence of BMP-TFSI in the mixed electrolyte contributes to the reduction of the flammability of electrolyte solution and the improvement of the thermal stability of charged $Li_{1-x}CoO_2$ in the electrolyte solution.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2016.05a
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• pp.71-72
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• 2016

In this paper, RTLS tag for high-precision positioning and wireless power transmission module is designed in order to solve the battery replacement problem. Wireless charging pad is available to charge the 4 RTLS tags at once. Charging time of the proposed protype in 50 cm distance is 22 minutes based on 3V reference voltage and 500 mW.

• Transactions on Electrical and Electronic Materials
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• v.8 no.4
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• pp.157-160
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• 2007

Lithium-sulphur batteries were fabricated in a dry room, and their electrochemical properties were analyzed by scanning electron microscopy (SEM), cyclic voltammetry (CV), and charge-discharge tests. SEM results showed that sulphur and nanocarbon powders were mixed homogeneously, and sulphur powders were enwrapped by a large amount of carbon powders. The charge-discharge test results demonstrated that the lithium-sulphur battery displayed excellent reversibility and cycling performance, which supplied a discharge capacity of $788.1mAh\;g^{-1}$ at the first cycle and $796.4mAh\;g^{-1}$ after 71 cycles at room temperature, respectively.

• Electronics and Telecommunications Trends
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• v.15 no.6 s.66
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• pp.128-139
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• 2000

반도체, LCD와 더불어 첨단 정보통신기기의 소형화, 경량화, 휴대형화 진전에 기여한 핵심기술로서 전지기술을 빼놓을 수 없다. 전지기술의 역사는 오래전에 이루어졌으나 아직도 많은 부분에서 개발이 진행되고 있는 분야이다. 특히 국내의 경우 반도체나 LCD에 비해 상대적으로 연구개발이나 투자가 미흡한 상태로서 고부가가치 장치산업이라는 점과 대량생산이 가능하다는 점에서 향후 전략적으로 중점 육성해야 할 분야라 할 수 있다. 본 고에서는 개인 휴대형 통신기기로부터 자동차 연료전지에 이르기까지 전기.전자 및 정보통신 분야에서 중요한 비중을 차지하고 있는 고성능 2차전지에 대하여 기본적인 기술개요와 특성, 2차전지의 종류와 최근의 개발동향을 살펴보고 세계시장을 주도하고 있는 미국과 일본의 개발 및 시장현황에 대하여 조사 정리하였다.

• Proceedings of the KIEE Conference
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• 1993.07a
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• pp.464-466
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• 1993

In this paper, a peak detection algorithm having high reliability is proposed. The peak detection algorithm is implemented to a charger and power control system which is applicable to home appliances or notebook PC directly. The charger and power control system is controlled by a microprocessor, M50927 (Mitzubishi), to improve cost to performance ratio. The charger algorithm is designed to be operated under optimal charge node and various protections are added tn improve the reliability of the charger.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.12 no.1
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• pp.50-55
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• 1999

We have investigated the $LiMn_2O_4$system as an cathode material for lithium rechargeable batteries. $LiMn_2O_4$spinel oxides have been synthesized by a solid state methode. We varied sintering time at a fixed sintering temperature of 75$0^{\circ}C$. In order to investigate the electrochemical properties of prepared $LiMn_2O_4$we assembled three-electrode cells using the working electrode as active material and Li metal as the counter and reference electrodes. The electrolyte was 1 M LiPE$_{6}$-EC:DEC(1:1 by volume). The particle size of sample synthesized at 75$0^{\circ}C$ ranged about 60$\mu m$. The discharge capacity of a cell involving spinel $LiMn_2O_4$ increased with increasing sintering time.e.

• International Journal of Internet, Broadcasting and Communication
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• v.14 no.4
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• pp.80-87
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• 2022

Lack of sufficient battery capacity is one of the most important challenges impeding the development of wireless sensor networks (WSNs). Recent innovations in the areas of wireless energy transfer and rechargeable batteries have made it possible to advance WSNs. Therefore, in this article, we propose an energy-efficient charging of sensors in a WSN scenario. First, we have formulated the problem as an integer linear programming (ILP) problem. Then a utility function-based greedy algorithm named UGreedy/UF1 is proposed for solving the problem. Finally, the performance of UGreedy/UF1 is analyzed along with other baseline algorithms: UGreedy/UF2, 2-opt TSP, and Greedy TSP. The simulation results show that UGreedy/UF1 performs better than others both in terms of the deadline missing ratio of sensors and the total energy consumption of UAVs.

• Applied Chemistry for Engineering
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• v.34 no.4
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• pp.365-382
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• 2023

A lithium metal anode with high energy density has the potential to revolutionize the field of energy storage systems (ESS) and electric vehicles (EVs) that utilize rechargeable lithium-based batteries. However, the formation of lithium dendrites during cycling reduces the performance of the battery while posing a significant safety risk. In this review, we discuss various strategies for achieving dendrite-free lithium metal anodes, including electrode surface modification, the use of electrolyte additives, and the implementation of protective layers. We analyze the advantages and limitations of each strategy, and provide a critical evaluation of the current state of the art. We also highlight the challenges and opportunities for further research and development in this field. This review aims to provide a comprehensive overview of the different approaches to achieving dendrite-free lithium metal anodes, and to guide future research toward the development of safer and more efficient lithium metal anodes.