• Journal of the Korean Ceramic Society
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• v.54 no.4
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• pp.298-302
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• 2017

To investigate the influence of alkaline impurity K content on bubbles of quartz glass, samples were prepared based on $SiO_2$ sand with differing amounts of potassium hydroxide solution added by electric fusion. Bubble properties such as number, diameter and bubble fraction were determined using a stereoscopic microscope. The results of the observations indicated that an alkaline impurity content of 100 ppm had a good effect on bubble decline in quartz glass. The effect on OH was investigated by FTIR(Fourier transform infrared spectroscopy).

• Journal of the Korean Wood Science and Technology
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• v.44 no.5
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• pp.743-749
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• 2016

The concentration control of wood preservatives is necessary to produce a preservative treated wood having a uniform quality. Concentration measurement method of wood preservatives to be easily used in the field has not been developed yet. This study examined the way to estimate the concentration from turbidity of ACQ wood preservative that can be relatively easily measured by using a portable turbidity meter. The addition of phosphoric acid solution in an alkaline ACQ solution having a very low turbidity is created a suspension of the white substance and the turbidity suddenly increased. The optimum amount of addition of the phosphoric acid solution is until the pH of ACQ solution reaches 7, the turbidity of the ACQ solution reaches maximum value. Excessive addition of the phosphoric acid solution results in a turbidity decrease with acidification of the ACQ solution. Also ACQ solution becomes transparent. The high significance was recognized with positive correlation between the concentration and the turbidity of the ACQ solution. From the t-test, The significant difference between the actually measured concentrations and the concentrations predicted by the regression equation for industrial ACQ solutions was not recognized. Thus, it was possible to know that concentration prediction and control of industrial ACQ solution using the turbidity and a regression equation. Therefore, using the regression equation and turbidity is expected to be able to management the concentration of ACQ solution in the industrial field.

• Journal of the Korean Chemical Society
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• v.23 no.3
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• pp.180-185
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• 1979

Electrochemical reduction behavior from 2-butyne-1, 4-diol (BID) to 2-butene-1,4-diol (BED) by the use of various cathodes, such as Ti, Zr, Ni, Pt, Cu, Ag, Au, Zn, Hg, Pb and graphite has been studied. It has been found that cathodic polarization curve with metal of IB subgroup such as Cu, Ag and Au consisted of one wave in BID-alkaline solution, whereas it was not formed any wave in BED solution. Therefore, it was found that the cathode which was the most suitable in order to proceed in this reaction was Cu, Ag and Au. At cyclic voltammetry using a silver cathode in BID-alkaline solution, the current of the peak was proportional to square root of the sweep rate of potential and also proportional to concentration of BID. Activation energy was calculated for 3.75 kcal/mole from the plot of log $I_l$ vs. 1/T. Consequently, the reduction current of BID with a silver cathode in alkaline solution was found the diffusion current.

• Journal of Ocean Engineering and Technology
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• v.27 no.5
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• pp.10-15
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• 2013

The crack-healing behavior and corrosion resistance of SiC ceramics were investigated. Heat treatments were carried out from $900^{\circ}C$ to $1300^{\circ}C$. A corrosion test of SiC was carried out in acid and alkaline solutions under KSL1607. The results showed that heat treatment in air could significantly increase the strength. The heat-treatment temperature has a profound influence on the extent of crack healing and the degree of strength recovery. The optimum heat-treatment temperature was $1100^{\circ}C$ for one hour at an atmospheric level. In the two kinds of solutions, the cracks in a specimen were reduced with increasing time, and the surface of the crack healed specimen had a greater number of black and white spots. The strength of the corroded cracked specimen was similar to that of the cracked specimen. The strength of the corroded crack healed specimen decreased 47% and 75% compared to that of the crack healed specimen in the acid and alkaline solutions, respectively. Therefore, the corrosion of SiC ceramics is faster in an alkaline solution than in an acid solution.

• YAKHAK HOEJI
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• v.13 no.1
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• pp.22-27
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• 1969

Nicotinamide Complex Compound was not formed in simple alkaline solution under two to one molar ratio of dimethyglyoxime and Fe (II), but it was formed with ammonia or pyridine under the same molar ratio. Based on this fact, nicotinamide solution was added into dimethyglyoxime-Fe (II) complex solution, and the chelation product was extracted with chloroform. The extraction was Completed in a range of pH 8.4-11.0. The chloroform solution shows stability and maximum absorption at 516 m${\mu}$.

• Journal of Pharmaceutical Investigation
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• v.23 no.4
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• pp.225-229
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• 1993

The stability of omeprazole in the aqueous solutions containing arginine or sodium phosphate dibasic(SPD) was examined at 30, 40 and $50^{\circ}C$. Arginine or anhydrous SPD was added to omeprazoie solution ($200{\mu}g/\;ml$ in distilled water) to yield $100{\mu}g/\;ml$ concentration of each. Then, the solution was kept at 30, 40 or $50^{\circ}C$ for 90 hrs. Aliquots of the solution were withdrawn at specified time intervals and assayed by HPLC for intact omeprazole. The remaining percentage-time curves revealed that omeprazole was degraded rapidly as funtions of time and temperature following pseudo first-order kinetics. The rate constant in the SPD solution was much higher than in the arginine solution. In other words. the degradation half-lives of omeprazole at $30^{\circ}C$, for example, was 148 and 76 hr in arginine and SPD solutions respectively. The initial pH of the solution containing $100{\mu}g/\;ml$ of arginine or SPD was 9.7 or 8.7, respectively. Since omeprazole is more stable as the pH of its solution becomes more alkaline, the longer half-life of omeprazole in arginine solution could be explained by the more alkaline characteristics of arginine than SPD in the solution. The activation energy necessary for the degradation reaction was almost identical in both solutions, indicating similar degradation mechanisms of omeprazole in the solutions. In conclusion, omprazole was more stable in the presence of arginine than of SPD.

• Journal of Environmental Science International
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• v.15 no.2
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• pp.177-183
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• 2006

The hydrolytic kinetics of biodegradable poly(l-lactide) (PLLA) have been studied by using two model systems, solution-grown single crystal (SC) and Langmuir monolayer techniques, for elucidating the mechanism for both alkaline and enzymatic degradations. The present study investigated the parameters such as degradation medium and time. The Langmuir mono layers of PLLA showed faster rates of hydrolysis when they were exposed to a basic subphase rather than they did when exposed to neutral subphase. Both degradation mediums had moderate concentrations to show a maximized activity, depending on their sizes. An alkaline degradation of SCs of PLLA showed the decrease of molecular weight of the remained crystals due to the erosion of chain-folding surface. However, the enzymatic degradation of SCs of PLLA occurred in the crystal edges thus the molecular weight of remained crystals was not changed. This behavior might be attributed to the size of enzymes which is much larger than that of alkaline ions; that is, the enzymes need larger contact area with monolayers to be activated.

• Advances in environmental research
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• v.5 no.2
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• pp.141-151
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• 2016

Large amounts of aluminum hydroxide ($Al(OH)_3$) exist in water purification sludge (WPS) because of the added aluminum coagulant in water treatment process. Notably, $Al(OH)_3$ is an amphoteric compound, can be dissolved in its basic condition using sodium hydroxide to form aluminate ions ($Al(OH)_4{^-}$). However, in a process in which pH is increasing, the humid acid can be dissolved easily from WPS and will inhibit the recovery and reuse of the dissolved aluminate ions. This study attempts to fix this problem by a novel approach to separate $Al(OH)_4{^-}$ ions using nanofiltration (NF) technology. Sludge impurity in a alkaline solution is retained by the NF membrane, such that the process recovers $Al(OH)_4{^-}$ ions, and significantly decreases the organic matter or heavy metal impurities in the permeate solution. The $Al(OH)_4{^-}$ ion is an alkaline substance. Experimental results confirm that a recovered coagulant of $Al(OH)_4{^-}$ ion can effectively remove kaolin particles from slightly acidic synthetic raw water.

• Journal of the Korean Chemical Society
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• v.16 no.6
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• pp.354-360
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• 1972

Formation of the complexes of barium, strontium and calcium ions with dibasic organic acid ions in dilute solution was studied at room temperature, utilizing the equilibrium exchange technique which involved the uses of radioactive alkaline earth metal ions and cation excbange resin. The organic acids used in this study were succinic and tartaric acids, and the solvents used were water, 20 % acetone-water and 20 % ethanol-water. The pH of the solutions was controlled to 7.2∼7.4, and the ionic strength of the solutions was kept at approximately 0.1. The experimental results indicated that the alkaline earths formed one-to-one complexes in solution with the dibasic acids examined, and that the relative stabilities of the complexes increased in the order: $Ba^{++}; succinic

• Advances in concrete construction
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• v.5 no.4
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• pp.313-330
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• 2017

Geopolymer is a sustainable concrete, replaces traditional cement concrete using alternative sustainable construction materials as binders and alkaline solution as alkaline activator. This paper presents the strength characteristics of geopolymer concrete (GPC) developed with fly ash and GGBS as binders, combined Sodium silicate ($Na_2SiO_3$) and Sodium Hydroxide (NaOH) solution as alkaline activators. The parameters considered in this research work are proportions of fly ash and GGBS (70-30 and 50-50), curing conditions (Outdoor curing and oven curing at $600^{\circ}C$ for 24 hours), two grades of concrete (GPC20 and GPC50). The mechanical properties such as compressive strength, split tensile strength and flexural strength along with durability characteristics were determined. For studying the durability characteristics of geopolymer concrete 5% $H_2SO_4$ solutions was used and the specimens were immersed up to an exposure period of 56 days. The main parameters considered in this study were Acid Mass Loss Factor (AMLF), Acid Strength Loss Factor (ASLF) and products of degradation. The results conclude that GPC with sufficient strength can be developed even under Outdoor curing using fly ash and GGBS combination i.e., without the need for any heat curing.