• Journal of Nutrition and Health
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• v.31 no.2
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• pp.213-219
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• 1998

This study was conducted to compare and evaluate the iodide specific ion electrode method (ISE) and neutron activation analysis method (NAA) for determining iodine in human milk and cow milk. The neutron irradiation and counting operations were carried out at the TRIGA Mark-III reactor facility of the Korea Atomic Energy Research Institute. The mean concentrations of iodine in human milk samples by the ISE and the NAA were 1450$\mu\textrm{g}$/L and 1350$\mu\textrm{g}$/L, respectively. The levels were not significantly different. In cow milk samples , the mean concentrations of iodine by the ISE and the NAA were 250$\mu\textrm{g}$.L and 200$\mu\textrm{g}$/L, respectively. here, the ISE reading was significantly higher than the NAA. reading. The correlations of the two methods were 0.92(p<0.001) for human milk samples and 0.65 for cow milk samples . The coefficient of variation was 8.3% in the ISE and 4.9% in the NAA. Therefore, the iodide specific ion electrode method is sample and fast method, but probably not in processed milk since free sulfhydryl groups in milk are also detected by the iodide electrode. However, these also indicate that the ISE method may be applicable to human milk and pasteurized milk if the conventional pasteurization time-temperature relationship of standards is not exceeded. On the other hand, the NAA method , which is independent of chemical forms and matrix, can be used for determining iodine in all kinds of milk and foods.

• Nuclear Engineering and Technology
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• v.32 no.6
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• pp.595-604
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• 2000

Flow-Accelerated Corrosion Behavior of SA106 Gr.C steel in room temperature alkaline solution simulating the CANDU primary water condition was studied using Rotating Cylinder Electrode. Systems of RCE were set up and electrochemical parameters were applied at various rotating speeds. Corrosion current density decreased up to pH 10.4 then it increased rapidly at higher pH. This is due to the increasing tendency of cathodic and anodic exchange half-cell current. Corrosion potential shifted slightly upward with rotating velocity. Passive film was formed from pH 9.8 by the mechanism of step oxidation and the subsequent precipitation of ferrous species into hydroxyl compound. Above pH 10.4, the film formation process was active and the film became stable. Corrosion current density showed increment in pH 6.98 with the rotating velocity, while it soon saturated from 1000 rpm above pH 9.8. This seems that activation process which represents formation of passive film on the bare metal surface controls the entire corrosion process

• Particle and aerosol research
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• v.15 no.4
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• pp.183-190
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• 2019

Here, we introduce porous graphene balls (PGB) showing superior electrochemical properties as supercapacitor electrode materials. PGB was fabricated via activation of graphene oxides (GO) by H₂O₂ and aerosol spray drying in series. Effect of activation on the morphology, specific surface area, pore volume, and electrochemical properties were investigated. As-prepared PGB showed spherical morphology containing pores, which lead to the effective prevention of restacking in graphene sheets. It also exhibited a large surface area, unique porous structures, and high electrical conductivity. The electrochemical properties of the PGB as electrode materials of supercapacitor are investigated by using aqueous KOH under symmetric two-electrode system. The highest specific capacitance of PGB was 279 F/g at 0.1 A/g. In addition, the high rate capability (93.8% retention) and long-term cycling stability (92.2%) of the PGB were found due to the facilitated ion mobility between the porous graphene layers.

• Bulletin of the Korean Chemical Society
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• v.34 no.9
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• pp.2781-2786
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• 2013

We examined the effect of electrode fingers and gaps of coplanar interdigitated electrode (IDE) structures to characterize the ammonium salt-containing polyelectrolyte film of resistance-based humidity sensors. IDEs designed for this purpose were flexible gold electrodes deposited on a polyimide substrate using a printing process because the geometry presents a potential for tunable sensitivity over other electrode designs. The basic design of the sensors consisted of IDEs with a different number of electrode fingers such as 3, 4, and 5 and gap sizes of 310, 360, 410, and $460{\mu}m$. Details of the AC complex impedance characteristics such as the Nyquist plot, Bode plot, and activation energy based on electrode construction were investigated.

• Transactions of the Korean hydrogen and new energy society
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• v.34 no.2
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• pp.178-186
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• 2023

Three activation methods (constant voltage, current cycling, and hydrogen pumping) were applied to investigate the effects on the performance of the membrane electrode assembly (MEA) loaded with PtCo/C catalyst. The current cycling protocol took the shortest time to activate the MEA, while the performance after activation was the worst among the all activation methods. The constant voltage method took a moderate activation time and exhibited the best performance after activation. The hydrogen pumping protocol took the longest time to activate the MEA with moderate performance after activation. According to the distribution of relaxation time analysis, the improved performance after the activation mainly comes from the decrease of charge transfer resistance rather than the ionic resistance in the cathode catalyst layer, which suggests that the existence of water on the electrode is the key factor for activation.

• Journal of the Korean Chemical Society
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• v.33 no.2
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• pp.225-231
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• 1989

The heterogeneous rate constants for the electrochemical reduction by $trans-[Co(en)_2X_2](ClO_4)_n$(where X is cyanide, nitrite, ammonia, and isothiocyanate) at mercury and glassy carbon electrode were investigated by cyclic voltammetry, DC polarography, and by using rotating disk electrode. The good linear relationship was obtained between the activation energy of reduction and absorption wave number of complexes on glassy carbon electrode. At mercury electrode, $NO_2^-$ ligated complex showed the large deviation from the linear relationship. The difference in the value of rate constants for $NO_2^-$ ligated complex between mercury and glassy carbon electrode was about three order of magnitude which was much larger than the other complexes. It was suggested that $NO_^-$ ligated complex was reduced by inner-sphere mechanism on mercury electrode from the larger value of activation energy and entropy on mercury than carbon electrode.

• Corrosion Science and Technology
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• v.2 no.1
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• pp.41-46
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• 2003

Flow-Accelerated Corrosion behavior concerning both activation and mass transfer process of SA106 Gr.C steel was studied using rotating cylinder electrode in room temperature alkaline solution by DC and AC electrochemical techniques. Passive film was tanned from pH 9.8 by step oxidation of ferrous product into hydroxyl compound. Corrosion potential shifted slightly upward with rotating velocity through the diffusion of cathodic species. Corrosion current density increased with rotating velocity in pH 6.98, while it soon saturated from 1000 rpm at above pH 9.8. On the other hand the limiting current increased with rotating speed regardless of pH values. It seems that activation process, which represents formation of passive film on the bare metal surface, controls the entire corrosion kinetics

• Transactions of the Korean hydrogen and new energy society
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• v.32 no.4
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• pp.256-262
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• 2021

A carbon felt electrode was prepared using ozone and ammonia sequential treatment and applied as an electrode for a vanadium redox flow battery (VRFB). The physical and electrochemical analyses demonstrate that the oxygen groups facilitate nitrogen doping in the carbon felt. Carbon felt (J5O3+NH3), which was subjected to ammonia heat treatment after ozone treatment, showed higher oxygen and nitrogen contents than carbon felt (J5NH3+O3), which was subjected to ammonia heat treatment first and then ozone treatment. From the charging/discharging of VRFB, the J5O3+NH3 carbon felt electrode showed 14.4 Ah/L discharge capacity at a current density of 150 mA /cm², which was 15% and 33% higher than that of J5NH3+O3 and non-activated carbon felt (J5), respectively. These results show that ozone and ammonia sequential treatment is an effective carbon felt activation method to increase the performance of the vanadium redox flow battery.

• Journal of Energy Engineering
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• v.2 no.3
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• pp.300-307
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• 1993

To develop high performance nickel-iron secondary battery, the characteristics of charge-discharge reaction of iron electrode were examined by cyclic voltammetry technique, SEM and XRD analysis. The capacity of the test electrodes was determined by the constant current charge-discharge method. It was found that the temperature and concentration of electrolyte were the major determinant factors of electrode capacity, and especially the 1st discharge capacity was increased with the increase of temperature. The effect of fore forming agent on the electrode capacity was negligible. The electrode capacity was above 350 ㎃h/g(36% utility) at 0.25C discharge rate. The stability of electrode was very good, but the activation occurred slowly.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1999.05a
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• pp.473-476
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• 1999

PMOS capacitors with Ce-policide electrode were fabricated by the SADS method to study the effects of activation condition on the C-V characteristics. For the activation temperature of $600^{\circ}C$ , the capacitor using CoSi$_2$ formed from Co/Ti bilayer as diffusion source showed excellent C-V properties and the increase in V$_{th}$ with the increasing activation time. But impurties into the oxide.e.