• Membrane Journal
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• v.15 no.4
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• pp.349-354
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• 2005

YSZ (yttria-stabilized zirconia) determined with an electrolyte that analyzed thermal stability along sintering condition and an electric characteristic. As sintering temperature increases by SEM, grain grows and it showed that pore decreases relatively. and confirmed effect by grain size. It evaluated that particle internal resistance and electric performance by resistance in an electrolyte and electricity conductivity measurement through ac impedance measurement in temperature of $800\~1000^{\circ}C$ in 2-probe method In order to recognize an electric characteristic. In dry process and wet process, density was each 6.13, 6.25 $g/cm^3$ and the relative density was each 98, 99$\%$ when sintering condition is $1400^{\circ}C$.

• Journal of Korean Society of Environmental Engineers
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• v.37 no.4
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• pp.204-209
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• 2015

The effluent limit of nickel from electroplating wastewater has been strengthened from 5 mg/L to 3 mg/L from 2014. However, currently applied treatment process for nickel plating wastewater is unable to meet the effluent limit, most of the treatment concept conducted by treatment plant is dilution with other metal bearing wastewater. This can cause very significant impact to the environment of nickel contamination. With this connection, the feasibility test has been conducted with the use of electrolysis by using sacrificial electrodes. Experiments were conducted in synthetic and electroless nickel plating wastewater. Optimal condition of current density, pH were derived from the synthetic wastewater. It was found that the removal efficiency of nickel exceeded 94% at the operation condition of at pH 9 and the current density of $1{\sim}2mA/cm^2$. At this conditions, the iron sludge was generated very low amount. However, it was unsuccessful to meet the effluent limit by applying these treatment conditions to the real electroplating wastewater. This can be explained due to the matrix effect of other metals and anions contained real electroplating wastewater. From the result of further study, the optimal conditions for the real wastewater treatment were found out to be at pH 9, current density $6{\sim}7mA/cm^2$, for 5 minutes of operating time. At these conditions, 88% removal of nickel was achieved, which results the residual nickel concentration was below 3 mg/L.

• Resources Recycling
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• v.21 no.6
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• pp.45-50
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• 2012

The room-temperature electrodeposition of metallic lithium was investigated from ionic liquid, 1-methyl-1-propylpiperidinium bis(trifluoromethanesulfonyl)imide (PP13TFSI) with lithium bis (trifluoromethanesulfonyl)imide (LiTFSI) as a lithium source. Cyclic voltammograms on gold working electrode showed the possibility of the electrodeposition of metallic lithium, and the reduction current on a gold electrode was higher than the value on platinum and copper. The metallic lithium could be electrodeposited on the gold electrode under potentiostatic condition at -2.4 V (vs. Pt-QRE) and was confirmed by analytical techniques including XRD and SEM-EDS. The dendrite-typed electrodeposits were composed of a metallic lithium and a alloy with gold substrate. And any impurity could be detected except for trace oxygen introduced during handling for the analyses.

• Journal of Advanced Marine Engineering and Technology
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• v.38 no.8
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• pp.1010-1020
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• 2014

Ballast water effluent treated by an electrolytic method contains reactive chlorine species and disinfection by-products (DBPs). In this study, we conducted whole effluent toxicity (WET) testing and ecological risk assessment (ERA) to investigate its ecotoxicological effects on marine environment. WET testing was carried out for three marine pelagic organisms, i.e., diatom Skeletonema costatum, rotifer Brachionus plicatilis and fish Paralichthys olivaceus. The biological toxicity test revealed that S. costatum was the only organism that showed apparent toxicity to the effluent; it showed no observed effect concentration (NOEC), lowest observable effect concentration (LOEC) and effect concentration of 50% (EC50) values of 12.5%, 25.0% and 83.3%, respectively, at brackish water condition. In contrast, it showed insignificant toxicity at seawater condition. B. plicatilis and P. olivaceus also showed no toxicities to the effluent at the both salinity conditions. Meanwhile, chemical analysis revealed that the ballast water effluent contained total residual oxidants (TROs) below $0.03{\mu}g/L$ and a total of 20 DBPs including bromate, volatile halogenated organic compounds (VOCs), halogenated acetonitriles (HANs), halogenated acetic acids (HAAs) and chloropicrin. Based on ERA, the 20 DBPs were not considered to have persistency, bioaccumulation and toxicity (PBT) properties. Except monobromoacetic acid, the ratio of predicted environmental concentration (PEC) to predicted no effect concentration (PNEC) of the other 19 DBPs did not exceed 1. Thus, our results of WET testing and ERA indicated that the ballast water effluent treated by electrolysis and subsequently neutralization was considered to have no adverse impacts on marine environment.

• Journal of the Korea Convergence Society
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• v.8 no.11
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• pp.287-292
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• 2017

The electrodeposition of Zn on the automotive parts has been adapted However, because Zn electrodeposit needs to increase thickness for corrosion protection, it has problem of destruction of electrodeposit Zn-based electrodeposit have teen studied for corrosion protection and decreasing electrodeposit thickness. Especially; Zn-Co electrodeposit have much attention In this study, the Composition of Zn-Co electrodeposit in various manufacturing condition such as temperature, current density and electrolyte content was investigated to understand effect of electrolysis condition on Co content of specimen. The results were explained by cathode overvoltage and diffusion coefficient. As the current density increases, the electrolyte temperature decreases, and as the electrolyte concentration decreases, the overvoltage of the cathode increases. As the overvoltage of the cathode increases, the concentration polarization becomes more important than the activation polarization. Concentration polarization is determined by the diffusion of the mass transfer in the diffusion layer. In a constant concentration polarization, a large amount of elements with a large diffusion coefficient is diffused. That is, as the overvoltage of the cathode increases, the Zn content having a large diffusion coefficient increases.

• Applied Microscopy
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• v.23 no.2
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• pp.1-10
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• 1993

The effect of electrolyte on the extraction replicas of the precipiates in 3% Si steel was investigated. Three Kinds of electrolyte, 2% Nital solution (2% nitric acid+methanol; acid solution),, Sodium Citrate solution (5% sodiumcitrate+1% KBr+0.5KI+$H_{2}O$; aqueous neutral solution) and 10% AA solution (10% acetylacetone+ 1% tetramethylammoniumchloride+methanol; non-aqueous neutral solution), were compared. The preciptiates in 3% Si steel were dissolved in 2% Nital, but they were not dissolved in the Sodium Citrate and 10% AA solution. In Sodium Citrate solution, however, large second artifacts were introduced during sample preparation. Therefore 10% AA solution was found to be most useful for the preparation of extraction replica. The electrolysis condition of a matrix and precipitates were also checked by the measurement of potential-current curve in 10% AA solution. The matrix was electrolyzed at -400mV with respect to SCE(Saturated Calomel Electrode). In contrats precipitates were electrolyzed above 300mV. Precipitates were respected to be stable in 10% AA solution in the range of $-380mV{\sim}-300mV$ usually used to prepare extraction replicas.

• Journal of Surface Science and Engineering
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• v.27 no.5
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• pp.292-302
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• 1994

Alloy deposits of 80Sn-20Pb, electroplated on Cu-based leadframe alloy from an organic sulfonate bath were aged at $150^{\circ}C$ to form intermetallic phases between substrate and deposit, and effects of the deposit morphology, influenced by deposition conditions, on the fracture resistance of the 80Sn-20Pb deposit aged at $150^{\circ}C$ were examined. The growth rate of intermetallic compound layer on aging depended on the microstructure of deposit ; it was fastest in deposit formed using pulse current in bath without grain refining additive, but slowest in deposit formed using dc current in bath containing grain refining additive in spite of similar structure with equivalent grain size. The grain refining additive incorporated in electrodeposit appears to inhibit diffusion of atoms on aging, resulting in slow growth of intermetallic layer in the thickness direction but substantial growth in the lateral one. Density of surface cracks that were occurring when samples were subjected to the $90^{\circ}$-bending test increased with increasing the thickness of intermatallic layer on aging. For the same aged samples, the surface crack density of the sample electrodeposited from a bath containing the grain refining additive was the least due to the inhibiting effect of the additive incorporated into the deposit during electrolysis on atomic diffusion.

• Journal of Surface Science and Engineering
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• v.20 no.3
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• pp.118-126
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• 1987

The Zn-Al composite electroplating was studied by using chloride zinc bath containing metal hydroxides $(Zn(OH)_2,\;Al(OH)_3))$ and aluminium powder. The size of Al powder codeposited in the beaker bath with Al powder of-400 mesh was under 10${\mu}m$. The Zn-Al composite was electro-deposited at 40$^{\circ}C$ in the ranges of current density of 5-50 A/$dm^2$ in the flowing electrolyte. The content of aluminium particles codeposited increased slightly with increasing flow rate of electrolyte from 0.5 m/sec to 1.0 m/sec, and decreased with increasing current density from 5 A/$dm^2$ to 50 A/$dm^2$. The content of aluminium particles codeposited by using the electrolyte containing zinc hydroxide(0.1M) was 2~4 wt%. The Al powder was codeposited mainly near the surface layer of the electrodeposits. The dissolution rate of aluminium particles in the electrolyte containing 0.1M $Zn(OH)_2$ and Boric acid was 0.41 g/l. day in comparison with 1.5 g/l. day dissolution rate in pure chloride bath.

• 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.

• Journal of the Korean Chemical Society
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• v.68 no.5
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• pp.259-273
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• 2024

This study aimed to investigate changes in metamodeling recognition among chemistry teachers through a teacher educational program related to redox models and water electrolysis experiments. To this end, a science model education program was developed for 9 chemistry teachers and conducted over 10 lessons for a total of 40 hours. In addition, a pre- and post-survey was administered to determine teachers' metamodeling recognition in non-contextual and contextual situations. As a result of the study, through the science model education program, teachers showed educational effects in both non-contextual and contextual situations. In the case of non-contextual situations, the stages of scientific metamodeling knowledge development of chemistry teachers came out differently depending on the type of question. For example, the nature or purpose of the model, the modeling process, or the evaluation and improvement of the model improved from low to high, but there was no significant change because the perception of model change and diversity was already high in advance. In the case of contextual situations, the stage of scientific metamodeling knowledge development improved from objectivity to subjectivity in both the redox model theory class and the water electrolysis model experiment class. Therefore, through the 5E circular learning model-based education program, chemistry teachers' perception of metamodeling was clearly improved. However, the modeling activities of teachers in the water electrolysis model experiment class were different from the change in metamodeling perception. The types that teachers selected as additional experiments for modeling were analyzed in two ways. The first type is when they are interested in finding an ideal condition in which the ratio of hydrogen and oxygen gas is close to 2:1 through additional experiments. The second type is when additional experiments are designed with interest in why the experimental results are coming out like that. It was analyzed that the second type was the experiment necessary for modeling. In addition, modeling activities were analyzed into two types. The first was a type in which water molecules were directly decomposed in two electrodes to generate hydrogen and oxygen gas. This type was the case of regression to the textbook model regardless of the experimental results, and 6 chemistry teachers out of 8 were analyzed as this type. The second type was the type in which water reacted at the (+) electrode to generate other substances, and hydrogen ions reacted at the (-) electrode to generate hydrogen gas. Teachers who performed these modeling activities corresponded to the second type in additional experiments, and 2 chemistry teachers out of 8 corresponded to this. Therefore, it is necessary to provide an experience of activities corresponding to the second type of experiment and modeling through an educational program that provides an experience of directly modeling through experiments in order to develop modeling capabilities, unlike the development of metamodeling knowledge.