• Bulletin of the Korean Chemical Society
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• v.34 no.1
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• pp.79-88
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• 2013

$LiFePO_4$ is a promising active material (AM) suitable for use in high performance lithium-ion batteries used in automotive applications that require high current capabilities and a high degree of safety and reliability. In this study, an optimization of the electrode design parameters was performed to produce high capacity lithium-ion batteries based on $LiFePO_4$/graphite electrodes. The electrode thickness and porosity (AM density) are the two most important design parameters influencing the cell capacity. We quantified the effects of cathode thickness and porosity ($LiFePO_4$ electrode) on cell performance using a detailed one-dimensional electrochemical model. In addition, the effects of those parameters were experimentally studied through various coin cell tests. Based on the numerical and experimental results, the optimal ranges for the electrode thickness and porosity were determined to maximize the cell capacity of the $LiFePO_4$/graphite lithium-ion batteries.

• Journal of the Korean Society of Industry Convergence
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• v.26 no.1
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• pp.27-34
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• 2023

This study conducted a study on a small-capacity PCS using lithium-ion batteries used in personal mobility. Most of the batteries in Personal Mobility only charge with external chargers and are used only as mobile energy sources. However, this paper aims to charge the battery of PM using PV and system power or to use the charged power as a stand-alone power supply. The developed PCS can be operated as a two-channel battery charger/discharger, a battery charger using solar power, and a stand-alone solar inverter depending on the operation method. The validity of the manufactured small-capacity PCS was verified through experiments.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2003.11a
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• pp.602-606
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• 2003

Silicon has been developed as an alternate anode material for lithium secondary batteries. A simple approach to improve the electrical contact of silicon powder has described. Carbon-coated and silver-coated silicon have been prepared by chemical vapor deposition and electroless plating respectively. Assembled cells, which consisted of surface modified silicon, lithium foil and $Li^+$ contained organic electrolyte, have been studied using electrochemical methods. Carbon-coated silicon was improved in the electrochemical performance such as reversibility and resistance compared to surface-unmodified silicon.

• Journal of Biomedical Engineering Research
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• v.24 no.1
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• pp.45-53
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• 2003

Based on the 4-compartmental pharmacokinetic model developed in PART1, target-controlled infusion(TCI) pump system was designed and evaluated. The TCI system consists of digital board including microcontroller and digital signal process(DSP), analog board, motor-driven actuator, user friendly interface, power management and controller. It provides two modes according to the drugs: plasma target concentration and effect target concentration. Anaesthetist controls the depth of anaesthesia for patients by adjusting the required concentration to maintain both plasma and effect site in drug concentration. The data estimated in DSP include infusion rate, initial load dose, and rotation number of motor encoder. During TCI operation, plasma concentration. effect site concentration, awaken concentration, context-sensitive decrement time and system error information are displayed in real time. Li-ion battery guarantees above 2 hours without power line failure. For high reliability of the system, two microprocessors were used to perform independent functions for both pharmacokinetic algorithm and motor control strategy.

• Proceedings of the IEEK Conference
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• 2003.07b
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• pp.895-898
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• 2003

본 논문에서는 휴대폰에 사용하는 리튬-이론 배터리(Li-Ion battery)를 충전하기 위한 충전 IC 의 설계에 대해서 기술한다. 정전류(Constant Current)/ 정전압 (Constant Voltage) 방식을 이용하여 리튬-이론 배터리를 충전을 하였다. 이 충전 과정을 제어하기 위해서 일반적으로 사용되는 ADC, DAC 와 MICOM 을 사용하지 않고, hardwired control logic 을 이용하여 적은 면적을 가지고도 기존의 충전 과정을 수행하도록 하였다. 충전 IC 외부에 사용되는 저항들을 내부에 집적하여 사용하는 부품의 수를 현저히 줄였다. 충전기와 리튬-이온 배터리를 연결하는 선(wire)로 저항에 의한 전압강하(voltage drop)를 외부에서 보상할 수 있도록하여 리튬-이온 배터리가 가장 안정적인 전압인 4.2 V로 충전 될 수 있도록 하였다. 외부 온도 검사 블록에서 저항을 이용한 전압 분배를 사용하지 않고, 정전류원을 이용하여 외부 온도 변화를 측정할 수 있도록 하였다. 리튬-이온 배터가 전정류와 정전압으로 4.2 V로 충전 되었으며, 충전 IC 의 소비 전력은 37 mW(analog part)이다. 충전 IC는 0.6 ㎛ standard CMOS 공정을 이용하여 설계하였다.

• Journal of Energy Engineering
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• v.19 no.1
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• pp.39-50
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• 2010

Hybrid Electric Vehicle(HEV) and Plug-in Hybrid Electric Vehicle(PHEV) will replace Conventional Gasolene Engine Vehicle at a rapid rate to eliminate emission gases and improve fuel economy. This review describes Fuzzy Logic Control strategy and Optimization for Parallel Hybrid Electric Vehicle. Recent progress on Electric Motor and Li-ion Battery for HEV and PHEV are given. Analysis on competitiveness of Korean HEV and PHEV technology based on the number of papers published and patents registered are also performed.

• Journal of Power Electronics
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• v.18 no.3
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• pp.910-922
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• 2018

Conventional battery state-of-charge (SoC) estimation methods either involve sophisticated models or consume considerable computational resource. This study constructs an enhanced coulomb counting method (Ah method) for the SoC estimation of lithium-ion batteries (LiBs) by expanding the Peukert equation for the discharging process and incorporating the Coulombic efficiency for the charging process. Both the rate- and temperature-dependence of battery capacity are encompassed. An SoC mapping approach is also devised for initial SoC determination and Ah method correction. The charge counting performance at different sampling frequencies is analyzed experimentally and theoretically. To achieve a favorable compromise between sampling frequency and accumulation accuracy, a frequency-adjustable current sampling solution is developed. Experiments under the augmented urban dynamometer driving schedule cycles at different temperatures are conducted on two LiBs of different chemistries. Results verify the effectiveness and generalization ability of the proposed SoC estimation method.

• Proceedings of the KIPE Conference
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• 2018.07a
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• pp.69-71
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• 2018

기존 전기자전거의 경우에 사용되는 일반 배터리팩 방식에 비해 이중 배터리 팩 (Li-ion Batterty + Super Capacitor)의 방식이 동등 주행 성능 및 지속 시간 조건에서 무게 및 원가 저감이 가능하다. 또한 기존 승압형 Converter인 Boost Converter는 이중 배터리를 이용시 큰 inrush 전류를 발생시키고 이 전류로 인해 소자 파손에 문제가 있다. 따라서 본 논문에서는 입력 전압을 Li-ion Battery로, 출력 전압에 Super Capacitor를 연결하는 이중 배터리로 구성되고 기존 Boost converter 입력단에 Mosfet과 Diode를 추가하여 inrush 전류가 발생하지 않게 한다. 본 논문에서는 제안된 회로의 이론적 특성을 분석하고 실험을 통해 타당성을 검증하였다.

• 한국전기화학회:학술대회논문집
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• 2000.12a
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• pp.51-62
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• 2000

Large plastic Li-ion (PLI) cells (25 to 28-Ah) were fabricated for an EV application. The 28-Ah cells showed high specific energy (160 Wh/kg), high specific power (526 W/g), excellent round-trip energy efficiency $(92\%)$, and low self-discharge rate ($6\%$ in 30 days). A 25-Ah cell of an earlier design showed good cycle life of up to 750 cycles at $100\%$ DOD to $80\%$ of its initial capacity, while cycle life test of a 28-Ah cell of a later design is in progress. Preliminary safety tests were also carried out using 6-Ah cells of a similar electrode design giving very encouraging results for development of a safe hish-energy density PLI battery for EV application.

• Bulletin of the Korean Chemical Society
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• v.22 no.2
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• pp.189-193
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• 2001

The irreversible capacities caused by the reduction of solvent on the surface of a negative electrode (KMFC:Kawasaki Mesophase Fine Carbon) were examined during the initial cycle in ethylene carbonate (EC)-diethyl carbonate (DEC) electrolyte solut ions at various concentrations of LiPF6. Chronopotentiograms, linear sweep voltammograms, and impedance spectra clearly showed differences in irreversible capacity and that those differences are related to the concentration of electrolyte during the initial charge. These differences were caused by the amount of solvent decomposition as a function of the concentration of LiPF6 electrolytic salt. The data are discussed with reference to the concentration of electrolytic salt and the properties of passivation film formed by solvent decomposition.