• Korean Chemical Engineering Research
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• v.60 no.2
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• pp.202-207
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• 2022

The study on electrode degradation of Proton Exchange Membrane Fuel Cell (PEMFC) was mainly studied on the particle growth and active area reduction of Pt on the electrode. The degradation of the electrode catalyst Pt in contact with the membrane affects the deterioration of the polymer membrane, but there are not many studies related to this. In this study, the phenomenon of the deposition of deteriorated Pt inside the polymer membrane during the accelerated electrode catalyst degradation test and its effects were studied. The voltage change (0.6 V ↔ 0.9 V) was repeated up to 30,000 cycles to accelerate the platinum degradation rate. When the voltage change cycle was repeated while oxygen was introduced into the cathode, the amount of Pt deposited inside the film was larger than when nitrogen was introduced. As the number of voltage change cycles increased, the amount of Pt deposited inside the membrane increased, and Pt dissolved in the cathode moved toward the anode, showing a uniform distribution throughout the membrane at 20,000 cycles. In the process of the accelerated electrode catalyst degradation test, the hydrogen crossover current density of the membrane did not change, and it was confirmed that the deposited Pt did not affect the durability of the membrane.

• Korean Chemical Engineering Research
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• v.52 no.6
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• pp.695-700
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• 2014

Proton Exchange Membrane Fuel Cells (PEMFC) can generate hydrogen and oxygen from water by electrolysis. But the electrode and polymer electrolyte membrane degrade rapidly during PEM water electrolysis because of high operation voltage over 1.7V. In order to reduce the rate of anode electrode degradation, unsupported $IrO_2$ catalyst was used generally. In this study, Pt/C catalyst for PEMFC was used as a water electrolysis catalyst, and then the degradation of catalyst and membrane were analysed. After water electrolysis reaction in the voltage range from 1.8V to 2.0V, I-V curves, impedance spectra, cyclic voltammograms and linear sweep voltammetry (LSV) were measured at PEMFC operation condition. The degradation rate of electrode and membrane increased as the voltage of water electrolysis increased. The hydrogen yield was 88 % during water electrolysis for 1 min at 2.0V, the performance at 0.6V decreased to 49% due to degradation of membrane and electrode assembly.

• Journal of Electrical Engineering and Technology
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• v.6 no.1
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• pp.123-127
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• 2011

To clarify the relations of optical properties to the main factors responsible for the loss and damage of luminous efficacy, a 20 min turn-on/turn-off test for 2,000 h for a ceramic metal halide lamp is conducted. The corrosion rates of the arc tube wall and electrode are estimated based on thermal stress. Wall blackening is attributed to the tungsten being transported from the hot electrode tips to the relatively cold arc tube wall. Furthermore, the grain boundaries of the arc tube are changed by the degradation. Distortion of the electrode is observed, and the ignition and the driving voltage of the load both increase. Finally, the color rendering index and the color coordinates are changed after the degradation. The luminous flux and the intensity of the luminous distribution are decreased significantly.

• Korean Journal of Materials Research
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• v.9 no.10
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• pp.1032-1036
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• 1999

The electron emission and degradation of the ferroelectric Pb($\textrm{Zr}_{0.5}\textrm{Ti}_{0.5}$)$\textrm{O}_3$ ceramics by the pulse electric field have been investigated as a function of the upper electrode diameter. Polarization increased with the decrease of the upper electrode diameter due to the increase of the volume fraction participated in the polarization reversal near the electrode edge. Simulation using ANSYS 5.3 for the electric field distribution showed that the electric field increased near the upper electrode edge of the asymmetric electrode structure. The ferroelectric volume near the upper electrode edge which contributed to the increase of the polarization and the emission charge per electrode diameter were independent on the upper electrode diameter. Polarization and dielectric constant were decreased due to the erosion of the upper electrode with repeating the emission cycles, but they were recovered by the electrode regeneration. The degradation of the ferroelectric surface resulted in the increase of the coercive field and dielectric loss.

• Journal of Korean Society of Environmental Engineers
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• v.39 no.8
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• pp.489-493
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• 2017

Microbial fuel cells (MFC) are bio-electrochemical processes that can convert various organic materials present in wastewater into electrical energy. For scaling-up and practical application of MFC, it is necessary to investigate the effect of anode size, electrode distance, and total area of anode on substrate degradation. Spaced electrode assembly (SPA) type microbial fuel cell with multiple anodes treating domestic wastewater was used for simulation. According to computer simulation results, the shorter the distance between electrodes than the size of single electrode, the faster the substrate degradation rate. Particularly, when the total area of the anode is large, the substrate decomposition is the fastest. In this study, it was found that the size of the anode and the distance between the electrodes as well as the cathode electrode, which is known as the rate-limiting step in the design of the microbial fuel cell process, are also important factors influencing the substrate degradation rate.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.21 no.1
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• pp.82-89
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• 2017

In this work, InGaZnO thin film transistors with Ni, Al and ITO source and drain electrode materials were fabricated to analyze a hot carrier induced device degradation according to the electrode materials. From the electrical measurement results with electrode materials, Ni device shows the best electrical performances in terms of mobility, subthreshold swing, and $I_{ON}/I_{OFF}$. From the measurement results on the device degradation with source and drain electrode materials, Al device shows the worst device degradation. The threshold voltage shifts with different channel widths and stress drain voltages were measured to analyze a hot carrier induced device degradation mechanism. Hot carrier induced device degradation became more significant with increase of channel widths and stress drain voltages. From the results, we found that a hot carrier induced device degradation in InGaZnO thin film transistors was occurred with a combination of large channel electric field and Joule heating effects.

• Bulletin of the Korean Chemical Society
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• v.33 no.7
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• pp.2274-2278
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• 2012

To test the efficiency of the BDD electrode for complete mineralization of organic wastewater, phenol and 2-chlorophenol (2-CP) were treated electrochemically with both an active Pt/Ti electrode and a nonactive boron doped diamond (BDD) electrode, respectively, in neutral aqueous medium. Aqueous solutions of both phenol and 2-chlorophenol were treated electrochemically using an in-house fabricated flow through electrochemical cell (FTEC). The experimental variables included current input, treatment time, and the flow rate of the solutions. Depending on the magnitude of the applied current and reaction time, the compounds were either completely degraded or partially oxidized to other intermediates. Removal efficiencies reached as high as 93.2% and 94.8% both at the Pt/Ti electrode and BDD electrode, respectively, at an applied current of 200 mA for a 3.0 hr reaction and a flow rate of 4 mL/min. The BDD electrode was much more efficient for the complete mineralization of phenol and 2-chlorophenol than the Pt/Ti electrode.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2005.07a
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• pp.26-28
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• 2005

In this paper, degradation in field-aged PV modules including degradation of interconnect, discoloration of encapsulant and hot spot have been observed and analyzed. From the results, photovoltaic module installed for 15 years shows around 13~20% drop of electrical properties due to the interconnect degradation and PV module passed 19 years has been found to drop of around 20% mainly by the encapsulant discoloration. Fill factor of the electrode oxidized photovoltaic module has been dropped by the amount of 6~10% due to the change of irradiance. It is because maximum voltage(Vmp) decreases according to the increase of irradiance.

• Journal of Korean Society on Water Environment
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• v.27 no.2
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• pp.194-199
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• 2011

This study has been carried out to evaluate the performance of $PbO_2$ electrode for the purpose of degradation of N,N-Dimethyl-4-nitrosoaniline (RNO, indicator of OH radical), generation of ozone and decolorization of Rhodamine B (RhB) in water. The effect of the applied current (0.2~1.2 A), electrolyte type (NaCl, KCl and $Na_2SO_4$), electrolyte concentration (0.0~2.5 g/L) and solution pH (3~11) were evaluated. Experimental results showed that RhB and RNO removal were increased with the increase of current, NaCl dosage and decrease of pH. Ozone generation tendencies appeared with the almost similar to the RhB and RNO degradation, except of solution pH (Ozone generation was increased with increase of pH). Optimum current for RhB degradation and consumption of electric power was 1.0 A. The RhB degradation with Cl type electrolyte were higher than that with the sulfate type. Optimum NaCl dosage for RhB degradation was 1.0 g/L.

• Journal of the Korean Ceramic Society
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• v.33 no.11
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• pp.1231-1236
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• 1996

The electrode resistance of semiconducting PTC BaTiO3 ceramic material was studied in some detail. Comme-rical In-Ag paste In-Ga alloy and electroless plated Ni as well as evaporated Al were chosen as electrode. The contact resistance of electroded samples were measured by both dc resistivity and ac impedance analysis. The aging effect on contact resistance under cyclic loading from -1$0^{\circ}C$ to 85$^{\circ}C$ was also monitored for the prolonged period of time. In case of Al electroded samples the heat treatment and protective coating had effects on the stability against contact resistance degradation. It was also found that the samples with commercial In-Ag paste and electroless plated Ni electrode had good properties of contact resistance against aging.