• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2009년도 9th International Meeting on Information Display
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• pp.184-187
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• 2009

In this paper, we study effect of charge balance on performance of blue phosphorescent organic light emitting diodes (OLEDs). Charge balance determines the location of recombination zone in the OLEDs. By tuning the charge balance in iridium (III) bis[(4,6-difluorophenyl)-pyridinate-N,C2']picolinate (FIrpic) based blue phosphorescent organic light-emitting devices (PHOLEDs) with a high mobility and high triplet energy electron transporting material, we were able to achieve a high current efficiency of 60 cd/A which is a 3X improvement over previous devices with 3,5'-N,N'-dicarbazole-benzene (mCP) host.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2004년도 추계학술대회 논문집 Vol.17
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• pp.3-6
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• 2004

반도체 디자인, 공정 기술 및 패기지 기술의 발달에 따라 전력용 반도체는 소형화, 고성능화, 지능화하고 있다. 고속 구동이 용이한 때문에 MOSFET이나 IGBT등의 MOS-gate형 전력 반도체의 발전이 두드려지며, trench, charge balance, NPT 기술등이 패키지 기술과 더불어 이를 위한 주요 기술이 될것으로 보인다. SiC나 GaN등의 Wide Band Gap 물질들을 사용한 차세대 전력 반도체 연구도 활발히 진행되고 있다.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2011년도 추계학술대회 초록집
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• pp.82.2-82.2
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• 2011

A channel design which is closely related with the mass transport overpotential is one of the most important procedures to optimize the whole fuel cell performance. In this study, three dimensional results of a numerical study for gas distribution in channels of a molten carbonate fuel cell (MCFC) unit cell for a 1kW class stack was presented. The relationship between the fuel and air distribution in the anode and cathode channels of the unit cell and the electric performance was observed. A charge balance model in the electrodes and the electrolyte coupled with a heat transfer model and a fluid flow model in the porous electrodes and the channels was solved for the mass, momentum, energy, species and charge conservation. The electronic and ionic charge balance in the anode and cathode current feeders, the electrolyte and GDEs were solved for using Ohm's law, while Butler-Volmer charge transfer kinetics described the charge transfer current density. The material transport was described by the diffusion and convection equations and Navier-Stokes equations govern the flow in the open channel. It was assumed that heat is produced by the electrochemical reactions and joule heating due to the electrical currents.

• 전기화학회지
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• 제22권1호
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• pp.43-52
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• 2019

리튬이차전지(Lithium Secondary Batteries)를 에너지원으로 채용하는 분야가 다양해짐에 따라, 기존 요구 특성뿐만 아니라 각 분야에 특화된 성능 평가 결과까지 요구하고 있다. 이에 대응하기 위해 각 전지 제조사는 연구 인력을 충원하고 고가의 장비를 지속적으로 도입해서 다수의 전지를 오랜 기간 평가해야 하는 어려움을 겪고 있다. 이를 해소하기 위해, 전지 모델링(Modeling)을 기반으로 한 모사(Simulation) 기법을 도입하여, 실험 횟수를 최소화하고 실험 시간도 단축하려는 시도를 지속하고 있다. 현재까지 다양한 리튬이차전지 모델링 기법이 보고되고 있으며, 목적에 따라 최적 기법이 선택 및 활용되어 왔다. 본 리뷰 논문에서는 뉴만(Newman) 모델을 기반으로 한 전기화학적 모델링(Electrochemical Modeling) 기법을 상세히 설명한다. 특히, 전극 반응속도를 나타내는 버틀러-볼머식(Butler-Volmer Equation), 각 상(Phase)에서 전자와 이온의 균형 방정식 (Material and Charge Balance Equations), 그리고 전지의 온도 변화를 설명할 수 있는 에너지 균형 방정식 (Energy Balance Equation)의 물리적 의미를 쉽게 설명하고, COMSOL Multiphysics를 이용한 간단한 해석 과정과 결과를 제시한다.

• 전기화학회지
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• 제2권2호
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• pp.75-80
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• 1999

Li-ion 2차전지는 정극재료로 리튬전이금속산화물을, 부극재료로 탄소를 사용한다. 고용량 및 장수명을 지닌 Li-ion 2차 전지를 제작하기 위하여, 충전중에 탄소표면에 리튬 석출이 없이 전극 활물질의 이용율은 가능한 높아야 한다. 정극 및 부극 재료의 balance 및 적절한 충전 방식이 Li-ion 2차전지의 설계에 있어서 중요한 요소이다. 본 연구에서는 $LiCoO_2/MPCF$전지의 성능에 미치는 정$\cdot$부극 중량비의 효과를 고찰하였다. 먼저 각 반전지의 충방전 특성을 평가하였다. 그리고 흑연화 MPCF를 부극으로, $LiCoO_2$를 정극으로 사용하여 원통형 Li-ion 2차전지를 제작하였다. 기준전극으로 리튬금속을 사용하여 $LiCoO_2/MPCF$전지에서 각 반전지의 전위를 측정하였다. 또한 중량비에 따른 $LiCoO_2/MPCF$ 전지의 충방전 수명 성능을 평가하였다. 시험 결과, $LiCoO_2$ 정극의 이용율은 중량비에 의존하지 않지만, MPCF부극 이용율은 중량비에 크게 의존하였다. 또한, $LiCoO_2/MPCF$전지의 최적 중량비는 $2.0\~2.2$인 것으로 판단되었다.

• Journal of Electrochemical Science and Technology
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• 제2권3호
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• pp.152-156
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• 2011

A hybrid supercapacitor is fabricated using a composite material from $LiMn_2O_4$ (LMO) and activated carbon (AC) as the positive electrode and AC as the negative electrode to form the (LMO + AC)/AC system. Volume ratio (positive : negative) of electrodes is controlled to investigate of the power and energy balance. The (LMO + AC)/AC system shows better performances than the LMO/AC system. Especially, electrochemical impedance spectra, rate charge.discharge and cycle performance testing show that the (LMO + AC)/AC system have an outstanding electrochemical performance at volume ratios of (LMO + AC)/AC = 1 : 1.7 and 1 : 2. Electric double layer capacitor (EDLC) capacitance between AC of the positive electrode and AC of the negative electrode improves power density without loss of capacitance. Stable capacitance is achieved by lowering the positive electrode resistance and balancing the energy and power densities between the positive and negative electrodes by the addition of AC to the positive electrode at high current density.

• 한국전기전자재료학회논문지
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• 제26권8호
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• pp.587-590
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• 2013

Release competition and development of eco-friendly vehicles have been conducted violently also automaker, it will be a high growth industry of the charger and battery, which is the driving source of the motor of an electric vehicle. Reduces the on-resistance power elements DC - DC converter for battery charger for electric vehicles, must minimize switching losses. Should have a low on-resistance power than existing products. Compare the Super Junction MOSFET and Planar MOSFET, As a result, super junction MOSFET improve on about 87.4% on-state voltage drop performance than planar MOSFET.

• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2006년도 6th International Meeting on Information Display
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• pp.1775-1778
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• 2006

Through baking process on an interlayer, known as hole transporting layer, varying baking temperature up to 300 degree, which is considered as extremely high for polymer light emitting device (PLED) system, we found interesting relationship between packing density and morphology affecting device performance. Granular morphology shows that as temperature increases, grain size is getting smaller to pack closely and make interlayer harden. Such denser interlayer has temperature dependency of its own mobility, even without clear evidence of degradation of material itself. Its fact proven in a single film also reflects on multilayered PLED's performance like IVL, efficiency, lifetime. It's found that, especially, to enhance lifetime is related with thermal stability of interlayer and its mobility dependency to meet better charge balance. Therefore, it gives us understanding not only baking effect of interlayer, but also material & device designing guide to enhance lifetime.

• Transactions on Electrical and Electronic Materials
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• 제15권6호
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• pp.333-337
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• 2014

In this study, the use of a discharging process for charged particles is proposed to achieve an ideal electrical balance or neutralization and to improve the electrical and optical properties of a reflective electronic display. Here, negatively charged particles (white) and positively charged particles (black) are used. The q/m (charge per mass for a particle) values of the black and white particles are $+4.5{\mu}C/g$ and $-4.5{\mu}C/g$, respectively. We compared the movement of the charged particles by varying their discharging time. Stable movement of the charged particles is obtained with an appropriate discharging time, which resulted in improvements of the optical properties of the panel.

• 한국전기전자재료학회논문지
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• 제20권8호
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• pp.711-715
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• 2007

Properties of organic light-emitting diodes (OLEDs) with aluminum-doped zinc oxide (ZnO:Al) anodes showed different behaviors from OLEDs with indium tin oxide (ITO) anodes according to driving conditions. OLEDs with ITO anodes gave higher current density and luminance in lower voltage region and better EL and power efficiency under lower current density conditions, However, OLEDs with ZnO:Al anodes gave higher current density and luminance in higher voltage region over about 8V and better EL and power efficiency under higher current density over $200mA/cm^2$. These seemed to be due to the differences in conduction properties of semiconducting ZnO:Al and metallic ITO. OLEDs with ZnO:Al anodes showed nearly saturated efficiency under high current driving conditions compared with those of OLEDs with ITO anodes. This meant better charge balance in OLEDs with ZnO:Al anodes. These properties of OLEDs with ZnO:Al anodes are useful in making bright display devices with efficiency.