• Membrane Journal
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• v.31 no.4
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• pp.275-281
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• 2021

To evaluate the possibility as a separator in alkaline water electrolysis, the thermal stability, ion conductivity and durability of 5 commercially available anion exchange membranes were tested. The thermal stability of FAAM-PK-75 and FAAM-40 membrane analyzed by thermo-gravimetric analysis (TGA) showed good performance compared to the other three types of AEM, AHO, and AHA membrane. The ion conductivity of AEM membrane measured in 7 M KOH solution at 25℃ and 80℃ had a higher value of about 4~17 times compared to the other membranes. The durability of FAAM-PK-75 tested in 7 M KOH solution at 25℃ was high compared to the other membranes.

• Polymer(Korea)
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• v.27 no.2
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• pp.159-166
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• 2003

For the purpose of obtaining surface-anionized poly(vinyl alcohol) (PVA) hydrogel beads, vinyl acetate(VAc) and methacrylic acid(MMA) were copolymerized by the suspension polymerization technique and followed by the saponification. It was confirmed by $^1$H-NMR that the copolymerized microspheres contained carboxylic acid groups in their surface. poly(VAc-co-MAA) microspheres were completely saponified in the heterogeneous system. The saponification reaction was laster than that of PVAc microspheres. We observed the swelling property of saponified PVA microspheres treated in the acidic solution and in the alkaline solution successively. Saponified microspheres shrank in acidic solution and swelled in alkaline solution respectively, which was reversible. from the result, saponified microspheres were highly water-absorbing hydrogel beads and were certified -COOH group at their surface by $^1$H-NMR and FT-IR.

• Journal of the Korean Electrochemical Society
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• v.15 no.1
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• pp.54-66
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• 2012

The phase-shift method and correlation constants, which are unique electrochemical impedance spectroscopy techniques for studying the linear relationship between the phase shift ($90^{\circ}{\geq}-{\varphi}{\geq}0^{\circ}$) vs. potential (E) behavior for the optimum intermediate frequency ($f_o$) and the fractional surface coverage ($0{\leq}{\theta}{\leq}1$) vs. E behavior, are proposed and verified to determine the Frumkin, Langmuir, and Temkin adsorption isotherms and the related electrode kinetic and thermodynamic parameters. At Ni/0.5 M $H_2SO_4$ and 0.1M LiOH aqueous solution interfaces, the Frumkin and Temkin adsorption isotherms (${\theta}$ vs. E) of H for the cathodic hydrogen ($H_2$) evolution, interaction parameters (g), equilibrium constants (K), standard Gibbs energies (${\Delta}G^0_{\theta}$) of H adsorption, and rates of change (r) of ${\Delta}G^0_{\theta}$ with ${\theta}$ have been determined using the phase-shift method and correlation constants. A lateral repulsive interaction (g>0) between the adsorbed H species appears. The value of K in the alkaline aqueous solution is much greater than that in the acidic aqueous solution.

• Journal of the Korean Ceramic Society
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• v.49 no.6
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• pp.601-607
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• 2012

The alkali-activation reaction of two types of typical kaolin calcined at various lower temperatures was investigated at room temperature and at elevated temperatures. For the assessment of the reactivity, the temperature increase and the setting time of pastes prepared with calcined kaolin and sodium/potassium hydroxide solution were measured. Unlike raw kaolin, calcined kaolin samples prepared at various temperature showed an alkali-activation reaction according to the different aspects of the changes in the mineral phases. The reactivity with alkaline solutions was exceedingly activated in the samples calcined at $600-650^{\circ}C$, but the reactivity gradually decreased as the temperature increased in a higher temperature range, most likely due to the changes in the crystal structure of the dehydrated kaolin. The activation effect of the calcination treatment was achieved at reaction temperatures that exceeded $60^{\circ}C$ and was enhanced as the temperature increased. The reactivity of the calcined kaolin with an alkaline solution was more enhanced with the solution of a higher concentration and with a solution prepared from sodium hydroxide rather than potassium hydroxide.

• Advances in concrete construction
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• v.10 no.3
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• pp.237-245
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• 2020

Past research efforts already established geopolymer as an environment-friendly alternative binder system for ordinary Portland cement (OPC) and recycled aggregate is also one of the promising alternative for natural aggregates. In this study, an effort was made to produce eco-friendly mortar mixes using geopolymer as binder and recycled fine aggregate (RFA) partially and study the resistance ability of these mortar mixes against the aggressive environments. To form the geopolymer binder, 70% fly ash, 30% ground granulated blast furnace slag (GGBS) and alkaline solution comprising of sodium silicate solution and 14M sodium hydroxide solution with a ratio of 1.5 were used. The ratio of alkaline liquid to binder (AL/B) was also considered as 0.4 and 0.6. In order to determine the resistance ability against aggressive environmental conditions, acid attack test, sulphate attack test and rapid chloride permeability test were conducted. Change in mass, change in compressive strength of the specimens after the immersion in acid/sulphate solution for a period of 28, 56, 90 and 120 days has been presented and discussed in this study. Results indicated that the incorporation of RFA leads to the reduction in compressive strength. Even though strength reduction was observed, eco-friendly mortar mixes containing geopolymer as binder and RFA as fine aggregate performed better when it was produced with AL/B ratio of 0.6.

• Nuclear Engineering and Technology
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• v.56 no.2
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• pp.419-425
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• 2024

The purpose of this study is to improve the concentration of U(VI) in carbonate solution reasonably, which to improve the application potential of the alkaline reprocessing processes. The dissolution behavior of U₃O₈ in carbonate peroxide solutions was investigated under different conditions, including pH, carbonate concentration, and solid-liquid ratio. The results showed that the dissolution rate of U₃O₈ increased with the increase of pH from 8 to 11 in the mixed carbonate solution containing 0.5 mol/L H₂O₂. The role of carbonate ions in the dissolution of U₃O₈ was further elucidated by observing the dissolution of UO₄⋅4H₂O in carbonate solutions. Furthermore, the concentration of U(VI) in 3 mol/L Na₂CO₃ solution was successfully increased to 350 g/L under ultrasonic-assisted conditions at 60 ℃ and a solid-liquid ratio at 1/2 g/mL. Meanwhile, it is suggested that increasing the concentration of carbonate ions can improve the stability of the dissolved solution containing uranyl peroxycarbonate complex.

• Journal of Ocean Engineering and Technology
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• v.21 no.4
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• pp.61-65
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• 2007

In this research, we have developed a manufacturing process for seawater salt by horizontal spray drying technique using the deep ocean water and seaweed(sea tangle). Deep ocean water, strong acidic electrolyzed water and strong alkaline electrolyzed water were used as extraction solvent of seaweed. Sodium content in seaweed extract solution by strong alkaline electrolyzed water was 1.63(mg/g), which was 3.5 times lower than of seaweed extract by strong acidic electrolyzed water. Major mineral content(Na, K, Ca) in seawater salt by deep ocean water were higher than strong acidic electrolyzed water and strong alkaline electrolyzed water. On the contrary, Mg contents in seawater salt by deep ocean water were lower than strong acidic electrolyzed water and strong alkaline electrolyzed water. Based on the results of seawater salt production using seaweed, it is possible to make law-salt efficiently.

• Textile Coloration and Finishing
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• v.15 no.2
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• pp.86-92
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• 2003

It is already known that the color of wool fabric dyed with disazo acid dyes could be changed in dyeing process and this is accelerated under alkaline condition. Focus was given to figuring out the mechanism of this color change, through the LC-MS analysis. In this study, no color change was seen in wool fabrics dyed with C. I. Acid Blue 113 under weak acidic, neutral and weak alkaline conditions for 1hour. However, the wool fabrics dyed under weak alkaline condition for a long time over 3 hours fumed reddish orange. When the wool fabrics dyed under weak acidic, neutral and weak alkaline conditions were treated with $0.5g/L\;Na_2C0_3$ solution, all of them turned reddish orange. On the other hand, the color of silk fabrics dyed with C. I. Acid Blue 113 were not changed after the same alkaline treatment. Wool contains cystine and cysteine, whereas silk does not. Due to the reversible reduction/oxidation process of cystine and cysteine in wool dyeing, the C. I. Acid Blue 113 of the dis-azo type is decomposed by reduction and consequently turned them into the reddish orange mono-azo types dye.

• Korean journal of food and cookery science
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• v.14 no.3
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• pp.207-212
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• 1998

The changes in physicochemical properties of potato were investigated while steeping in water for 7 days at 30${\pm}$1$^{\circ}C$. The shape of raw starch granules was round or oval, the starch granule showed birefringence distinctly under polarized light and it was kept clearly even after steeping. X-ray diffraction pattern of the starch was B-type and there was no change in the pattern after steeping. However, crystallinity was increased up to the 4th day and then decreased. Amylose contents of raw starch and the starch steeped for 7 days were 19.3% and 13.1%, respectively. When the potato starch was gelatinized in 0.15 N sodium hydroxide solution, the viscosity was decreased until the 3rd day, but increased thereafter. Gel volume of the starch in KSCN solution was decreased during steeping.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2014.11a
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• pp.260-261
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• 2014

$TiO_2$ nanotubes (TNT) synthesized by microwave-assisted hydrothermal method by using $TiO_2-P25$ as a precursor at hydrothermal temperature $150^{\circ}C$ in 4 hours. The concentration of alkaline solution is between 4M and 10M. Samples were characterized by X-ray diffraction (XRD), Raman spectroscopy (RS), Transmission electron microscopy (TEM), Brunauer-Emmett-Teller (BET) and UV-vis DRS spectroscopy. The results demonstrated the effects of the alkali concentration to the formation of nanotubes. The photocatalytic activity was investigated by degradation of Methylene Blue (MB).