• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2018.06a
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• pp.71-71
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• 2018

현재 상용화된 Graphite 음극활물질의 경우 낮은 부피당, 무게당 용량을 가지며 이는 다양한 분야에 활용하는데 제약이 있다. $SiO_2$는 Si에 비해서는 낮은 용량이지만 metal oxide 계열 중 가장 높은 이론용량을 가지고 있으며, 리튬 이온과 반응 시 큰 부피팽창을 하며, 절연체로 전기전도도가 낮아 리튬이 차전지의 음극재로 상용화가 어려운 단점이 있다. 본 연구에서는 TEOS를 이용하여 탄소와 $SiO_2$를 동시에 $TiO_2$ microcone 구조에 코팅하여 3가지 물질의 복합체를 형성하여 용량을 증대시키고 구조적 안전성을 향상시키는 방법을 소개 한다. 음극재의 특성은 고분해능 주사전자현미경 (HR-SEM), 고분해능 엑스선 회절분석기 (XRD), 를 통해 조사하였으며, 순환전류법 (CV), 충 방전 싸이클 분석을 통해 리튬이차전지의 작동원리와 보다 향상된 성능을 규명하였다.

• Korean Chemical Engineering Research
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• v.46 no.1
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• pp.131-136
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• 2008

Silica- or titania-filled poly (vinylidene fluoride-co-hexafluoropropylene)-based polymer electrolytes were prepared by phase inversion technique using N-methyl-2-pyrrolidone and dimethyl acetamide as solvent and water as non-solvent. The polymer electrolytes were adopted to the lithium metal polymer battery using high-capacity cathode $Li[Ni_{0.15}Co_{0.10}Li_{0.20}Mn_{0.55}]O_2$ and lithium metal anode. After the repeated charge-discharge test for the cell, it was proved that the cell adopting the polymer electrolyte based on the phase-inversion membrane containing 40~50 wt% silica showed the highest discharge capacity (180 mAh/g) until 80th cycle and then abrupt capacity fade was just followed. The capacity fade might be due to the deposition of lithium dendrite on the polymer electrolyte, in which the capacity retention was no longer sustainable.

• Korean Chemical Engineering Research
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• v.56 no.3
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• pp.320-326
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• 2018

In this study, Graphite/Silicon/Carbon (G/Si/C) composites were synthesized to improve the electrochemical properties of Graphite as an anode material of lithium ion battery. The prepared G/Si/C composites were analyzed by XRD, TGA and SEM. Also the electrochemical performances of G/Si/C composites as the anode were performed by constant current charge/discharge, rate performance, cyclic voltammetry and impedance tests in the electrolyte of $LiPF_6$ dissolved inorganic solvents (EC:DMC:EMC=1:1:1 vol%). Lithium ion battery using G/Si/C electrode showed better characteristics than graphite electrode. It was confirmed that as the silicon content increased, the capacity increased but the capacity retention ratio decreased. Also, it was shown that both the capacity and the rate performances were improved when using the Silicon (${\leq}25{\mu}m$). It is found that in the case of 10 wt% of Silicon (${\leq}25{\mu}m$), G/Si/C composites have the initial discharge capacity of 495 mAh/g, the capacity retention ratio of 89% and the retention rate capability of 80% in 2 C/0.1 C.

• Membrane Journal
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• v.30 no.1
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• pp.21-29
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• 2020

In this study, we have established the optimum design condition of pore-filled anion-exchange membrane for all-vanadium redox flow battery (VRFB). From the experimental results, it was proven that the membrane design factors that have the greatest influence on the charge-discharge performance of VRFB are the ion exchange capacity, the porosity of substrate film, and the crosslinking degree. That is, the ohmic loss and the crossover of active materials in VRFB were shown to be determined by the above factors. In addition, two methods, i.e. reducing the ion exchange capacity at low crosslinking degree and increasing the crosslinking degree at high ion exchange capacity, were investigated in the preparation of pore-filled anion-exchange membranes. As a result, it was found that optimizing the crosslinking degree at sufficiently high ion exchange capacity is more desirable to achieving high VRFB charge-discharge performances.

• Journal of the Korean Institute of Gas
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• v.24 no.6
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• pp.91-97
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• 2020

Lithium-ion batteries (LIBs) have a longer lifespan, higher energy density, and lower self-discharge rates than other batteries, therefore, they are preferred as an Energy Storage System (ESS). However, during years 2017-2019, 28 ESS fire accidents occurred in Korea, and accurate capacity estimation of LIB is essential to ensure safety and reliability during operations. In this study, data-driven modeling that predicts capacity changes according to the charging cycle of LIB was conducted, and developed models were compared their performance for the selection of the optimal machine learning model, which includes the Decision Tree, Ensemble Learning Method, Support Vector Regression, and Gaussian Process Regression (GPR). For model training, lithium battery test data provided by NASA was used, and GPR showed the best prediction performance. Based on this study, we will develop an enhanced LIB capacity prediction and remaining useful life estimation model through additional data training, and improve the performance of anomaly detection and monitoring during operations, enabling safe and stable ESS operations.

• 한국전기화학회:학술대회논문집
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• 2000.04a
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• pp.32-32
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• 2000

• Journal of the Korean Professional Engineers Association
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• v.15 no.3
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• pp.12-18
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• 1982

Preliminary investigation have been made on what the capacity of high rate pulsed discharge of Ago-Zn button cells were associated with the changes of cathode construction feature, mix formulation, separator and electrolyte concentration.

• Proceedings of the KIEE Conference
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• 1987.07a
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• pp.45-46
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• 1987

• The Proceedings of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.9 no.1
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• pp.23-29
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• 1995

There are many articles about the HID lamps about it's characteristics and simulation methods for lamp design or ballast design. For the electronic ballasts of HID lamps, There are some problems caused by acoustic-resonance which destabilizes the arc of HID lamps. So, some studies suggest the methods to avoid it. For example, the methods suggested are high frequence driving over 100[kHz], and mixed frequence driving which alternates high frequence and low frequence, and squarewave driving etc. This study suggests the electronic ballast of HID lamps that solves the problems of acoustic-resonance, and can control the luminance by constant current boostes chopper of which frequence is 30[kHz] and by the squarewave driving of which frequence is 55.5[Hz.] As follows, we have the good electronic ballast for HID lamps which has the characteristics of a light weight, and a function of luminance control and a high quality luminosity and which saves electrical energy.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.3 no.4
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• pp.887-893
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• 1999

The characteristics of ozone generator targeted for air or water sterilizing in the vessel utilizing the surface corona discharge between the electrodes on the ceramic substrate was investigated by using the frequency control method. The frequency control was achieved by controlling the degree of resonance between the secondary winding inductance of transformer and the electrode capacitance of ceramic discharge plate, and the range of control was found to be 5 times of discharge current. This frequency control method showed the efficiency of 28 mP ozone generation and the stability within 3.4 % when the input voltage was varied within 40% range. The frequency control method is regarded to be more efficient way of corona discharge control compared to the conventional on/off control or voltage control methods.