• Korean Chemical Engineering Research
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• v.45 no.3
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• pp.242-248
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• 2007

For an optimal design of automotive electric system, it is important to have a reliable modeling tool to predict the charge-discharge behaviors of the automotive battery. In this work, a two-dimensional modeling was carried out to predict the charge-discharge behaviors of a 12-V automotive lead-acid battery. The model accounted for electrochemical kinetics and ionic mass transfer in a battery cell. In order to validate the modeling, modeling results were compared with the experimental data of the charge-discharge behaviors of a lead-acid battery. The discharge behaviors were measured with three different discharge rates of C/5, C/10, and C/20 at operating temperature of $25^{\circ}C$. The batteries were charged with constant current of 30A until the charging voltage reached to a predetermined value of 14.24 V and then the charging voltage was kept constant. The discharge and charge curves from the measurements and modeling were in good agreement. Based on the modeling, the distributions of the electrical potentials of the solid and solution phases, the porosity of the electrodes, and the current density within the electrodes as well as the acid concentration can be predicted as a function of charge and discharge time.

• Proceedings of the Korean Vacuum Society Conference
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• 2013.08a
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• pp.157.1-157.1
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• 2013

외부 Ballast Capacitor를 이용한 Voltage Doubler 전원장치를 이용하여 Micro size의 대기압 플라즈마를 발생장치를 개발하였다. 2개의 외부 Capacitor를 병렬로 연결하여 충전한 다음 외부 Capacitor를 직렬로 연결하여 전압을 2배압 시킨 상태에서 방전이 일어나도록 하였다. Capacitor의 충 방전 제어는 Switch Device인 Insulated Gate Bipolar Transistor (IGBT)를 사용하였다. 개발된 대기압 플라즈마는 외부 Capacitor와 인가전압을 독립적으로 변화시킬 수 있기 때문에 방전 시 전류 전압을 독립적으로 제어할 수 있으며 용도에 따라 Glow 방전에서 Arc 방전까지 제어가 가능하다. 본 연구에서는 900 V의 1.22 nF 외부 Capacitor 방전과 400 V의 10 nF 외부 Capacitor 방전을 비교하였다. 방전 시 전압파형과 전류파형은 서로 다르지만 소비된 방전에너지는 340 ${\mu}J$로 동일하다. ICCD camera와 Spectrometer를 이용하여 비교 분석을 실시하였다. 방전 image 및 Optical Emission Spectroscopy 분석을 이용하여 플라즈마의 온도, 밀도 등을 시간적, 공간적으로 분석하였다.

• Journal of the Korean Electrochemical Society
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• v.1 no.1
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• pp.28-32
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• 1998

The electrochemical behavior of film and charge-discharge capacity of Li-ion cell in 1 M $LiPF_6/EC:DME$ (1 : 1, by volume ratio) electrolyte solution was studied using chronopotentiometry, cyclic voltammetry, chronoamperometry, and impedance spectroscopy. The first irreversible capacity was higher than the second irrversible capacity because of solvent decomposition. Especially, passivation film that is electron insulating and ionic conducting were formed on the MPCF by solvent decomposition during the first charge. The solvated Li is co-intercalated with solvent into MPCF electrode. Part of the MPCF is expoliated during co-intercalation of solvent-Li. The MPCF ends up nonuniformly covered by a relatively thick layer of exfoliated particles embedded in a matrix of product by solvent decomposition.

• Proceedings of the KIPE Conference
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• 2008.06a
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• pp.154-156
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• 2008

본 논문은 대용량 충 방전 커패시터 부하를 갖는 CCPS (Capacitor Charging Power Supply)의 충전시간 제어방법을 제안한다. 기존의 대용량 Capacitor charger들은 LC공진탱크 및 스위칭 주파수를 개 루프 방식으로 제어한다. 이와 같은 제어 방법은 LC 공진탱크의 파라미터 변화로 인해 충전시간 제어가 불가능하다. 본 논문은 이러한 문제점을 해결하기 위해 Zero-crossing 방법을 이용 전류의 공진주파수를 검출한 뒤 스위칭 주파수를 가변 함으로서 원하는 시간과 안정성을 동시에 만족 할 수 있는 피드백 제어 방법을 제안한다.

• Journal of the Korean Electrochemical Society
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• v.7 no.1
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• pp.38-43
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• 2004

Porous carbon aerogel-silica gel composite materials were used as the electrodes of capacitive deionization(CDI) process, which were prepared by a paste rolling method. The electrochemical parameters such at current values, coulombs af a function of cycle, and CDI efficiencies were investigated for 10th and 100th cycles in 1,000ppm NaCl solution. Carbon aerogel-silica gel composite electrodes showed good wet-ability and higher mechanical strengths even under the NaCl solutions as well. In our experimented runs, all of the composite electrodes also are showed good cycle-ability without destroy of active material during cycles and decreased manufacturing times by $50\%$. Conclusively, the adding of silica gel powder to carbon aerogel leads to the effective performance of CDI process due to effective utilization of active materials by increasing the wet-ability and mechanical hardness.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.31 no.1
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• pp.55-62
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• 2021

In order to improve fuel economy and reduce CO2, HEV adopts ISG system as a standard. This ISG system increased the electric load that the battery had to bear, and the number of starting increased rapidly. AGM Lead Acid batteries have been developed and used, but the charging time is about three times longer as the electrolyte amount control during formation must be maintained at a higher level compared to conventional lead-acid batteries. In this study, we tried to shorten the charging time by increasing the charging efficiency through the optimization of the formation pattern. In order to optimize the Formation Pattern, 10 charging steps and 6 discharging steps were applied to 16 multi steps, and the charging current for each step was controlled, and the test was conducted under 4 conditions (21 hr, 24 hr, 27 hr, 30 hr). As a result of simultaneous application of multi-step and discharge step, it was verified that minimizing the current loss and eliminating the sudden polarization during charging contributes to the improvement of charging efficiency. As a result, it showed excellent results in reducing the charging time by about 30 % with improved charging efficiency compared to the previous one.

• The Journal of the Convergence on Culture Technology
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• v.9 no.3
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• pp.727-730
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• 2023

The operation of electric automatic windows is used in harsh environments, and the energy density decreases as charging and discharging are repeated, and as soundness deteriorates due to damage to the internal separator, the vehicle's mileage decreases and the charging speed slows down, so about 5 to 10 Batteries that have been used for about a year are classified as waste batteries, and for this reason, as the risk of battery fire and explosion increases, it is essential to diagnose batteries and estimate SOH. Estimation of current battery SOH is a very important content, and it evaluates the state of the battery by measuring the time, temperature, and voltage required while repeatedly charging and discharging the battery. There are disadvantages. In this paper, measurement of discharge capacity (C-rate) using a waste battery of a Tesla car in order to predict SOH estimation of a lithium-ion battery. A Support Vector Machine (SVM), one of the machine models, was applied using the data measured from the waste battery.

• 전기의세계
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• v.39 no.10
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• pp.28-36
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• 1990

태양광발전 시스템에서 축전지는 일조시간에 태양 전지에 의해 충전된 전력을 일몰 후와 같이 태양전지로 부터의 출력이 없을때나 흐린날, 우천시와 같이 태양 전지의 출력이 부족할 때 방전하여 부하에 전력을 공급하게 된다. 이와같이 축전지는 태양 광발전 시스템이라는 특별한 용도에 사용되기 때문에 일반적인 용도와는 달리 매우 가혹한 사용 조건하에서 가동된다. 즉, 축전지의 충전량은 기후 변화에 의해서 좌우되므로 과충전, 부족충전, 과방전이 진행되면 축전지의 노화 즉, 용량 감소는 급격히 일어나게 된다. 물론 최적의 충전 상태를 유지하기 위해서 충전기를 개량하거나, 부조일을 감안하면 축전지의 용량을 설계하거나, 디젤 보조발전기를 사용하여 일사량이 적은 경우에 충전 전기량을 보충하는 등 여러가지 개선책이 있지만, 불규칙적이며 가혹한 사용조건은 자연 현상에 의한 것이므로 근본적인 해결책은 될 수가 없다.

• Proceedings of the KIEE Conference
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• 2001.07b
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• pp.822-824
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• 2001

본 논문은 휴대용 발광 장치 충전을 위한 영구자석형 선형 발전기의 특성 해석을 담고 있다. 공간고조파법을 이용해 자계 해석 및 설계를 하였다. 발생 전압 및 저항에 따른 특성 비교와 충방전 시간 측정을 포함하고 있으며, 전기자 반작용 해석 결과도 포함되어 있다.

• Proceedings of the KIPE Conference
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• 2020.08a
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• pp.318-319
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• 2020

본 논문에서는 직류 시스템에 적용된 퓨즈를 수 ms 내에 용단시키기 위해 대전류를 주입하여 퓨즈의 I²t에 빠르게 도달시키는 방법을 제시한다. 대전류 주입을 목적으로 상시 충전된 커패시터를 퓨즈에 병렬 연결하여 과전류가 감지되면 방전시킨다. 커패시터에서 방전된 퓨즈에 흐르는 대전류는 I²t에 빠르게 도달시켜 수 ms내에 퓨즈를 용단시킨다. 제안하는 보호회로를 제작하고, 실험을 통해 성능을 검증하였다.