• Journal of the Korean Ceramic Society
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• v.40 no.1
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• pp.69-76
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• 2003

For lithium secondary microbattery anode, the tin oxide thin films with Si addition (0, 2, 6, 10, 20 ㏖%) were prepared with R.F. magnetron sputtering at substrate temperature of 30$0^{\circ}C$ and Ar:O$_2$=7:3 atmosphere. As Si addition amount increased, Si-O bonding density increased and Sn-O bonding density decreased. The addition of optimum Si amount led the decrease of Sn oxidation state so that the irreversible capacity reduced and cycle characteristic enhanced during charge-discharge test. SnO$_2$films with 6 ㏖% Si had the highest reversible capacity of 700 mAh/g after 100 cycles.

• Journal of IKEEE
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• v.24 no.1
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• pp.333-338
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• 2020

This paper proposes a method of estimating the SOC(State of Charge) of a battery cell using a neural network algorithm. To this, we implement a battery SOC estimation simulator and derive input and output data for neural network learning through charge and discharge experiments at various temperatures. Finally, the performance of the battery SOC estimation is analyzed by comparing with the experimental value by Ah-counting using Matlab/Simulink program and confirmed that the error rate can be reduced to less than 3%.

• The Transactions of the Korean Institute of Power Electronics
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• v.14 no.3
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• pp.188-196
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• 2009

Due to its high power density, long cycle life and clean nature supercapacitors are widely used for improving the dynamic characteristics of the new and renewable energy sources and extending the battery run-time and life. In this paper improved dynamic model of the supercapacitor is developed by the electrochemical impedance spectroscopy technique. The developed model can be used to accurately estimate the dynamic behaviour of the supercapacitor and calculate the exact capacitance value at a certain state of charges. The model of the supercapacitor in the frequency domain is equivalently transformed into that in the time domain for Matlab/Simulink simulaton. The simulation data shows fine agreements with experimental results, thereby proving the validity and the accuracy of the developed model.

• Transactions of the Korean hydrogen and new energy society
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• v.14 no.2
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• pp.122-130
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• 2003

Li/S 이차전지의 유황양극의 전기전도도를 향상시키고 유황이 충방전시 전해질내로 용출되는 것을 방지하기 위하여 multi-walled carbon nanotubes (MWNTs)를 thermal CVD 방법으로 제조하여 유황양극에 첨가하였다. 실험결과 첫 사이클에서 Li/S 이차전지의 방전용량은 485mAh/g-sulfur이었고, MWNT 첨가 이후에 유황양극의 cycle life와 rate-capability가 향상되는 것을 관찰할 수 있었다. 그러므로 MWNT는 polysulfide를 유황양극에 흡착시키는 동시에 good electric conductor로서 작용한다는 것을 알 수 있었다.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1997.11a
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• pp.275-278
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• 1997

We investigated effectness of sort and volume of conductive agent to charge/discharge capacity of LiMn$_2$O$_4$. LiMn$_2$O$_4$is prepared by reacting stoichiometric mixture of LiOH . $H_2O$ and MnO$_2$(mole ratio 1 : 2) and heating at 80$0^{\circ}C$ for 24h, 36h, 48h, 60h and 72h. All LiMn$_2$O$_4$cathode active materials show spinel structure. Cathode active materials calcined at 80$0^{\circ}C$ for 36h, charge/discharge characteristics and cycle stability have remarkable advantages. Used that super-s-black and 20wt% as conductive agent in LiMn$_2$O$_4$, it is excellent than property of cathode used Acetylene black or mixture of Super-s-black and acetylene black at charge/discharge capacity and cycle stability. Also, specific efficiency of cathode is excellent as over 98% and that of first cycle is excellent as 92%.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.7 no.6
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• pp.1292-1295
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• 2006

Three kinds of electrolyte membranes were prepared by impregnating filter papers with one of the electrolyte solutions fur primary manganese battery ($NH_4Cl$, $ZnCl_2$, and alkaline types) and hygroscopic agent ($CaBr_2$ or $CaCl_2$), respectively. The thickness of them was $250{\sim}300{\mu}m$, and they were very flexible. The electrochemical characteristics greatly depended on the hygroscopic agent to supply water to the cell. The electrolyte membrane containing $CaCl_2$ showed the highest ionic conductivity and the largest discharge capacity.

• KEPCO Journal on Electric Power and Energy
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• v.8 no.2
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• pp.181-187
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• 2022

As the charges/discharges of VRFB-ESS were repeated during 150cycles or more, the capacity of electrolyte in VRFB-ESS was decreased little by little. It results from the decreasing of the level of anolyte and the increasing of the valance value of the catholyte. Then, we tried to recover the capacity loss with 3 different ways. The first way was that the levels of anolyte and catholyte were allowed to be evenly equalized when the difference in the levels of two different electrolytes were severe. The second one was to lessen the valance value of the catholyte through the reduction reaction to 4-valant ions of 5-valant ions in the catholyte with the reductant, oxalic acid. The last one was that the all electrolytes of analyte and catholyte were allowed to be electro-chemically reduced to 3.5 of the valance value by oxidizing new electrolyte with 3.5 valance ions. The last way was the most effective to recover the capacity loss.

• Journal of IKEEE
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• v.26 no.4
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• pp.531-536
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• 2022

In order to efficeintly manage a battery, it is important to accurately estimate and manage the SOH(State of Health) and RUL(Remaining Useful Life) of the batteries. Even if the batteries are of the same type, the characteristics such as facility capacity and voltage are different, and when the battery for the training model and the battery for prediction through the model are different, there is a limit to measuring the accuracy. In this paper, We proposed the entropy index using voltage distribution and discharge time is generalized, and four batteries are defined as a training set and a test set alternately one by one to predict the health status of batteries through linear regression analysis of machine learning. The proposed method showed a high accuracy of more than 95% using the MAPE(Mean Absolute Percentage Error).

• Proceedings of the Korea Information Processing Society Conference
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• 2021.05a
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• pp.263-266
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• 2021

근래의 드론 산업은 다양한 분야에서 사용이 확대되고 있으나 규제 등 여러 가지 사회적 진입장벽으로 시장 진입에 애로사항이 도출되고 있다. 본 논문에서는 드론 산업의 여러 제약 중 배터리의 제한적인 용량으로 장시간 비행이 어려운 문제를 개선하고자 승강식 드론스테이션을 개발하였다. 승강식 드론스테이션은 드론의 비행 중 배터리가 방전될 시 충전 및 정비를 할 수 있고, 드론 간의 통신 중계기 역할을 수행한다. 본 논문에서는 스테이션에 드론이 접근 시 슬라이딩 도어를 개폐하기 위하여 초광대역 통신을 이용한 거리 측정과 위치 인식 시스템에 대한 내용을 기술하였다.

• Korean Chemical Engineering Research
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• v.45 no.2
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• pp.178-182
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• 2007

Non-aqueous supercapacitors by using activated C and $LiMn_2O_4$ as an active material in a positive electrode were prepared and characterized. From the cyclic voltammetry and AC impedance analysis, the capacitive effect by electric double layer of activated carbon and the faradic effect by intercalation/deintercalation of $Li^+$ ion were observed. Increasing the ratio of $LiMn_2O_4$, specific capacitances and energy densities of supercapacitor were increased. At the ratio of 0.86:0.14 ($LiMn_2O_4:C$), the maximum specific capacitance of 17.51 Wh/L and energy density of 23.83 F/cc were obtained, which were more than twice of those for a conventional electric double layer capacitor. Even after 1,000 charge/discharge cycle, the supercapacitor by using the electrode containing 14% of activated carbon and 86% of $LiMn_2O_4$ showed 60% better specific capacitance and energy density than that by using the electrode containing 100% activated carbon.