• Journal of the Korean Electrochemical Society
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• v.17 no.1
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• pp.7-12
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• 2014

There is increasing demand on the reducing the weight and the volume of the major components in lithium secondary battery to improve energy density. Separator not only provides pathway for lithium ion movement but also prevents direct contact between anode and cathode. Herein we fabricated polyethylene separator by varying biaxial stretching ratio to obtain membrane thickness of 16, 12, and $9{\mu}m$. Mechanical and thermal properties of the separator with different thickness were investigated. Also rate capability and charge-discharge cycle property up to 500 cycles were studied using coin type full-cell with $LiCoO_2$ and graphite as a cathode and an anode, respectively. All the cells using separator with different thickness demonstrated excellent capacity retention after 500cycles (around 80%). Considering the rate capability, cell using separator with thickness of $9{\mu}m$ showed best performance. Interestingly, separator thickness of $9{\mu}m$ was more resistant to heat contraction compared to that of $16{\mu}m$ separator.

• Applied Chemistry for Engineering
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• v.19 no.2
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• pp.228-235
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• 2008

Nickel plating thickness increased with the electric current density, and the augmentation was more thick in $6{\sim}10A/dm^2$ than low current. Hull-cell analysis was tested to evaluate the current density. Optimum thickness was obtained at a temperature of $60^{\circ}C$, and the pH fluctuation of 3.5~4.0. Over the Nickel ion concentration of 300 g/L, plating thickness increased with the current density. The rate of decrease in nickel ion concentration was increased with the current density. The quantity of plating electro-deposition was increased at the anode surface, which was correlated with the increase of plating thickness. The plating thickness was increased because of the quick plating speed. However, the condition of the plating surface becomes irregular and the minuteness of nickel plating layer was reduced with the plating rate. After the corrosion test of 25 h, it was resulted in that maintaining low electric current density is desirable for the excellent corrosion resistance in lustered nickel plating. According to the program simulation, the thickness of diffusion layer was increased and the concentration of anode surface was lowered for the higher current densities. The concentration profile showed the regular distribution at low electric current density. The field plating process was controlled by the electric current density and the plating thickness instead of plating time for the productivity. The surface physical property of plating structure or corrosion resistance was excellent in the case of low electric current density.

• Proceedings of the Korean Vacuum Society Conference
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• 2010.08a
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• pp.167-167
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• 2010

Indium tin oxide (ITO) has been widely used as transparent conductive oxides (TCOs) for transparent electrodes of various optoelectronic devices, such as liquid crystal displays (LCD) and organic light emitting diodes (OLED). However, indium has become increasingly expensive and rare because of its limited resources. In addition, ITO thin films have some problems for OLED and flexible displays, such as imperfect work function, chemical instability, and high deposition temperature. Therefore, multi-component TCO materials have been reported as anode materials. Among the various materials, IZTO thin films have been gained much attention as anode materials due to their high work function, good conductivity, high transparency and low deposition temperature. IZTO thin films with a thickness of 200nm were deposited on Corning glass substrate at different substrate temperature by pulsed DC magnetron sputtering with a sintered ceramic target of IZTO (In2O3 70 wt%, ZnO 15 wt%, SnO2 15 wt%). We investigated the electrical, optical, structural properties of IZTO thin films. As the substrate temperature is increased, the electrical properties of IZTO are improved. All IZTO thin films have good optical properties, which showed an average of transmittance over 80%. These IZTO thin films were used to fabricate organic light emitting diodes (OLEDs) as anode and the device performances studied. As a result, IZTO has utility value of TCO electrode although it reduced indium and we expect it is possible for the IZTO to apply to flexible display due to the low processing temperature.

• Applied Chemistry for Engineering
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• v.30 no.6
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• pp.687-693
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• 2019

As the hydrogen fuel cell market is expanded starting from hydrogen electric vehicle and power generation field, the demand for fuel cells and hydrogen increases recently. Therefore, research works on fuel cell durability and fuel efficiency are required in order to activate the fuel cell market and commercialization. A dead-ended anode system was used in this study to optimize the fuel cell performance and fuel efficiency. The effect of purge condition according to the applied current and hydrogen supply pressure on the fuel cell performance were evaluated. In addition, the influence of water back diffusion on the different electrolyte membrane thickness was analyzed. The accumulated water was purged with a solenoid valve in the case of 3% voltage decrease in the dead-ended anode system. The experiment was performed with the hydrogen supply pressure of 0.1~0.5 bar and purge duration of 0.1~1 second. A maximum fuel efficiency of 98.9% was achieved under the purge duration of 0.1 s and hydrogen supply pressure of 0.1 bar with a NR 211 (25.4 um) membrane. However, the fuel cell performance decreased in a long-term operation due to some frequent flooding. The fuel efficiency and purge interval increased due to decreased back diffusion rates of the water and nitrogen with a NR 212 (50.8 um) membrane.

• Journal of the Korean institute of surface engineering
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• v.18 no.3
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• pp.105-115
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• 1985

Lead-tin-copper ternary alloy electrodeposition is conducted onto the inner bore surface of plain bearings as an overlay in order to investigate the effect of slot width, current density and fluoboric acid concentration on the uniformity of overlay. The thickness of overlay is analyzed by means of current distribution resulting from the overvoltage of plating bath and the apparent distance between cathode and anode. The result demonstrate that the uniformity of overlay is remarkably dependent of the slot size and current density, but has little bearing on the fluoboric acid concentration over 100g/L. This present study indicates that uniform overlay is obtainable within the tolerable thickness of ${\pm}2{\mu}m$ by using the slot width of 22mm. The surface morphology examination also shows the important role of concentration polarization of the micro-uniformity of overlay. The micro-uniformity has improved at the low concentration polarization which resulted from operating at the low current density and high fluoboric acid concentration. The surface morphology of deposits exhibits the vivid pyramid crystalline in the plating condition of low concentration polarizatio and all deposits have columnar structure parallel to the applied electric field regardless of the electroplating condition used.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2005.06a
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• pp.207-210
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• 2005

In this paper, a two-dimensional cross-channel model was applied to investigate influence of the gas diffusion layer(GDL) property and flow field geometry in the anode side for proton exchange membrane fuel cell(PEMFC). The GDL is made of a porous material such as carbon cloth, carbon paper, or metal wire mesh. To the simplicity, the GDL is represented as a block of material containing numerous pathways through which gaseous reactants and liquid water can pass. The purpose of present work was to study the effect of the GDL thickness and the porosity, and flow field geometry by computational fluid dynamics(CFD)

• Transactions on Electrical and Electronic Materials
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• v.16 no.3
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• pp.124-129
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• 2015

Organic electronics are the domain in which the components and circuits are made of organic materials. This new electronics help to realize electronic and optoelectronic devices on flexible substrates. In recent years, organic materials have replaced conventional semiconductors in many electronic components such as, organic light-emitting diodes (OLEDs), organic field-effect transistors (OFETs) and organic photovoltaic (OPVs). It is well known that organic light emitting diodes (OLEDs) have many advantages in comparison with inorganic light-emitting diodes LEDs. These advantages include the low price of manufacturing, large area of electroluminescent display, uniform emission and lower the requirement for power. The aim of this paper is to model polymer LEDs and OLEDs made with small molecules for studying the electrical and optical characteristics. The purpose of this modeling process is, to obtain information about the running of OLEDs, as well as, the injection and charge transport mechanisms. The first simulation structure used in this paper is a mono layer device; typically consisting of the poly (2-methoxy-5(2'-ethyl) hexoxy-phenylenevinylene) (MEH-PPV) polymer sandwiched between an anode with a high work function, usually an indium tin oxide (ITO) substrate, and a cathode with a relatively low work function, such as Al. Electrons will then be injected from the cathode and recombine with electron holes injected from the anode, emitting light. In the second structure, we replaced MEH-PPV by tris (8-hydroxyquinolinato) aluminum (Alq₃). This simulation uses, the Poole-Frenkel -like mobility model and the Langevin bimolecular recombination model as the transport and recombination mechanism. These models are enabled in ATLAS- SILVACO. To optimize OLED performance, we propose to change some parameters in this device, such as doping concentration, thickness and electrode materials.

• Journal of the Korean Applied Science and Technology
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• v.35 no.4
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• pp.1338-1347
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• 2018

In this study, Ti-mesh based electrodes were fabricated for the application of anode to the electrolysis process for wastewater treatment using Pd electroless plating method. The removal performance of the prepared Pd / Ti-mesh electrode was evaluated as representative dye RO16, and the durability and performance were maximized by varying the electrode manufacturing conditions. As a result, it was confirmed that the coating condition had no significant effect on the performance, and that the heat treatment process greatly affected the performance and the durability was improved. In addition, we tried to maximize performance and durability by complexing Ir, Ru, and Ta. However, as the thickness of the layer increased due to the limitation of the coating method, the resistance increased and the performance decreased accordingly.

• Proceedings of the Korean Vacuum Society Conference
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• 2014.02a
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• pp.478.1-478.1
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• 2014

We investigated $MoO_3$ graded ITO electrodes for organic solar cells (OSCs) without PEDOT:PSS buffer layer. The effect of $MoO_3$ thickness on the electrical, optical, and structural properties of $MoO_3$ graded ITO anodes prepared by RF/DC magnetron co-sputtering system using $MoO_3$ and ITO targets was investigated. At optimized conditions, we obtained $MoO_3$ graded ITO electrodes with a low sheet resistance of 13 Ohm/square, a high optical transmittance of 83% and a work function of 4.92 eV, comparable to conventional ITO films. Due to the existence of $MoO_3$ on the ITO electrodes, OSCs fabricated on $MoO_3$ graded ITO electrode without buffer layer successfully operated. Although OSCs fabricated on ITO anode without buffer layer showed a low power conversion efficiency of 1.249%, OSCs fabricated on $MoO_3$ graded ITO electrode without buffer layer showed a outstanding cell performance of 2.545%. OSCs fabricated on the $MoO_3$ graded ITO electrodes exhibited a fill factor of 61.275%, a short circuit current of 7.439 mA/cm2, an open circuit voltage of 0.554 V, and a power conversion efficiency of 2.545%. Therefore, $MoO_3$ graded ITO electrodes can be considered a promising transparent electrode for cost efficient and reliable OSCs because it could eliminate the use of acidic PEDOT:PSS buffer layer.

• Journal of the Korean Society for Precision Engineering
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• v.29 no.11
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• pp.1183-1189
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• 2012

Organic light-emitting diodes (OLEDs) using microcavity effect have attracted great attention because they can reduce the width of emission spectra from organic materials, and enhance brightness from the same material. We demonstrate the simulation results of the radiation properties from top-emitting organic light-emitting diodes (TE-OLEDs) with microcavity structures based on the general electromagnetic theory. Organic materials such as N,N'-di (naphthalene-1-yl)-N,N'-diphenylbenzidine (NPB) as a hole transport layer and tris (8-hydroxyquinoline) ($Alq_3$) as emitting and electron transporting layer are used to form the OLEDs. The organic materials were sandwiched between anode such as Ni or Au and cathode such as Al, Ag, or Al:Ag. The devices were characterized with electroluminescence phenomenon. We confirmed that the simulation results are consistent with experimental results.