• Journal of Adhesion and Interface
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• v.2 no.3
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• pp.9-15
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• 2001

To estimate the effect of the surface state of the EVA foam on an adhesion, the surface was treated with solvents having different values of a solubility parameter and a surface tension. The morphology and the contact angle were measured by SEM and contact angle tester, respectively. The value of the critical surface tension(${\gamma}_{c,0}$) of the EVA foam calculated by Zismann plot was 27.08 dyne/cm. The surface state and the ${\gamma}_c$ of the EVA foam were changed by solvent treatment. The swelling ratio of EVA foam was influenced by solubility parameter of a solvent, on the other hand the degree of change in the surface state was dependent on a surface tension of a solvent. When a surface tension of solvent. When a surface tension of solvent is lower than ${\gamma}_{c,0}$ of the EVA foam, the wettability of a solvent was good and the surface state was greatly changed. The adhesion strength of EVA foam was greatly improved to above 600% as compared to that of the untreated one. As the ${\gamma}_c$ of EVA was closed to the surface tension of the primer, the good adhesion strength was obtained.

• Journal of the korean academy of Pediatric Dentistry
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• v.23 no.3
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• pp.640-658
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• 1996

The purpose of this study was to examine the mechanism of improving acid resistance of Nd-YAG laser irradiated tooth enamel and determine the most effective energy density for improving acid resistance. The bovine tooth enamel were lased with a pulsed Nd-YAG laser. The energy densities of exposed laser beam were varied from 10 to $70\;J/cm^2$. To investigate the degree of improving acid resistance by irradiation, all the samples were submerged to demineralize in 0.5 N $HClO_4$ solution for 1 minute. After 1 minute, 0.05 % $LaCl_3$ was added to the solution for interrupting the demineralization reaction. The amounts of dissolved calcium and phosphate in the solution were measured by using an atomic absorption spectrophotometer and the UV/VIS spectrophotometer, respectively. To examine the mechanism of improving acid resistance, X-ray diffraction analysis, infrared spectroscopy, and scanning electron microscopy were taken. The X-ray diffraction pattern of the samples were obtained in the $10^{\circ}{\sim}80^{\circ}2{\theta}$ range with $Cu-K{\alpha}$ radiation using M18HF(Mac Science Co.) with X-ray diffractometer operating at 40 KV and 300 mA. The infra-red spectra of the ground samples in 300 mg KBr pellets 10 mm diameter were obtained in the $4000cm^{-1}\;to\;400cm^{-1}$ range using JASCO 300E spectrophotometer. The scanning electron microscopy was carried out using JSM6400(JEOL Co.) with $500{\sim}2000$ times magnification. The results were as follow 1. The concentration of calcium dissolved from laser irradiated enamel with $50J/cm^2$ was significantly lesser than that of unlased control group (p<0.05) 2. From the result of the X-ray diffraction analysis, $\beta$-TCP, which increases acid solubility, was identified in lased enamel but the diffraction peaks of (002) and (004) became sharp with increasing energy density of laser irradiation. This means that the crystals in lased samples were grown through the c-axis and subsequently, the acid solubility of enamel decreased. 3. The a-axis parameter was slightly increased by laser irradiation, whereas the c-axis parameter was almost constant except for a little decrease at $50J/cm^2$. 4. In the infra-red spectra of lased enamels, phosphate bands ($600{\sim}500cm^{-1}$), B-carbonate bands (870, $1415{\sim}1455cm^{-1}$), and A-carbonate band ($1545cm^{-1}$) were observed. The amounts of phosphate bands and the B-carbonate bands were reduced, on the other hand, the amount of the A-carbonate band was increased by increase the energy density. 5. The SEM experiments reveal that the surface melting and recrystallization were appeared at $30J/cm^2$ and the cracks were observed at $70J/cm^2$. From above results, It may be suggested that the most effective energy density for improving acid resistance of tooth enamel with the irradiation of Nd-YAG laser was $50J/cm^2$. The mechanism of improving acid resistance were reduction of permeability due to surface melting and recrystallization of lased enamel and reduction of acid solubility of enamel due to decrease of carbonate content and growth of crystal.

• Applied Chemistry for Engineering
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• v.21 no.6
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• pp.638-642
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• 2010

After phthalonitrile derivatives were synthesized by the introduction of phenoxy, 2-naphthoxy or 4-trityl phenoxy group on ${\alpha}$- and ${\beta}$-position, oxovanadyl phthalocyanine (VOPc) derivatives containing electron-rich substituent group at different position were synthesized successfully in this investigation. The chemical structure of samples was determined by the means of $^1H$-NMR, MALDI-TOF mass spectroscopy, and FT-IR spectrometer. Also, optical and chemical properties were determined by the means of UV-Vis spectrometer, X-ray diffractometry, and thermo gravimetry. It was found that the maximum absorbing wavelength of VOPc derivatives ranged from 684 to 726 nm. Also, their solubility and Q-band were enhanced and shifted by the introduction of substitute group, respectively.

• Applied Biological Chemistry
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• v.33 no.4
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• pp.293-300
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• 1990

The physical and chemical properties of dry acorn starch(DS), defatted acorn starch (DFS) and reincorporated acorn starch(RIS) were investigated. Swelling power and solubility of all starch sample, were exhibited two stage behavior. It had a little change on the pasting temperature of DS and DFS but the peak viscosity and breakdown value of DFS was somewhat higher than those of DS and RIS. Flow behavior of gelatinized starch pastes showed a pseudoplastic behavior and flow behavior index was lower than unit The consistency coefficient showed concentration and temperature dependency. The activation energies of DS, DFS and RIS were from $1.70Kca1/g\;{\cdot}\;mol$ to $3.75Kca1/g\;{\cdot}\;mol$.

• Journal of the Korean Ceramic Society
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• v.43 no.7 s.290
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• pp.393-401
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• 2006

The development of Korean glaze originated from the development of ash glazes. Ash not only has strong solubility but also can shows the glaze a variety of different colors according to what the glaze has in it as the main component. In addition, it gives a feeling of lucidness and softness. For these reasons, there are a lot of needs for ash and many potters want to take advantage of ashes as glaze. But natural ashes have not been widely used as glaze primarily because it is relatively hard to find or manufacture. Considering the difficulty of finding or manufacturing natural ashes, this study aims to formulate synthetic ash which not only is available to the potters in general but also has the sam ε characteristics as the natural ashes. To achieve this aim, this study examines the characteristics of the pine tree ash, the main component of the glaze of celadon porcelains, and the red pepper stem ash, the main component of the brown glaze, both of which have been used by the Korean traditional potters. In this study, the alkaline component of the glaze. A important ingredient when the ashes are synthesized, was supplied by mixing of $Na_2CO_3$, Chungju limestone and rice straw ash. Furthermore, the synthetic ash, when it shows no change of pH in its composition rate of 6:2:2, was found to be usable as the most stable material. In conclusion, the formula which frits some raw $materials-Na_2CO_3$, Chungju limestone and rice straw ash-can duplicate the synthetic ash which is simila to the natural ash.

• Korean Journal of Soil Science and Fertilizer
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• v.49 no.5
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• pp.429-433
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• 2016

Adsorption and precipitation of cadmium (Cd) could be dependent on rate of P addition and Cd level in soil. Therefore, the objective of this study was to examine how addition rate of P affect mechanisms of Cd immobilization such as adsorption and precipitation in different levels of Cd in soil. Arable soils were spiked with inorganic Cd ($CdCl_2$) to give a total Cd concentration of 10, 100, and $1,000mg\;Cd\;kg^{-1}$. Monopotassium phosphate ($KH_2PO_4$, MPP) was selected as phosphate material and mixed with the pretreated arable soil at the rates of 0, 800, 1,600 and $3,200mg\;P\;kg^{-1}$. The mixture soils were incubated at $25^{\circ}C$ for 8 weeks in dark condition. Soil pH decreased with increasing MPP addition rate in all levels of Cd but negative charge of soil increased, thereby reducing 1 M $NH_4OAc$ extractable Cd. Soil solutions were undersaturated with respect to $CdCO_3$ and $Cd_3(PO_4)_2$ with all P addition rate in soil with low Cd level (${\leq}100mg\;Cd\;kg^{-1}$) but supersaturated in soil with high Cd level ($1,000mg\;Cd\;kg^{-1}$). From the above results, Cd solubility was controlled by precipitation of Cd minerals such as $CdCO_3$ and $Cd_3(PO_4)_2$ in soil with high Cd level but by Cd adsorption induced by increase in negative charge of soil with low level of Cd.

• Journal of the Korean Society for Precision Engineering
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• v.22 no.6 s.171
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• pp.168-174
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• 2005

Nowadays, the companies use polymer materials for many purposes fur they have many advantages. The costs of these materials take up too high a proportion of the overall cost of products that use these materials as their major material. It is advantage for polymer industries to reduce these costs. The microcellular foaming process was developed in the early 1980s to solve this problem and proved to be quite successful. Microcellular foaming process uses inert gases such as $CO_2,\;N_2$. As these gases solve into polymer matrices, many properties are changed. The microcellular foaming process makes the glass transition temperature of polymers to low, and diminish the residual stress of polymer matrices. Besides, the microcellular foaming process has several merits, impact strength elevation, thermal insulation, noise insulation, and raw material saving etc. In previous research, many facts of microcellular foaming process are founded its characteristics. But previous researcher found the characteristics of microcellular foaming process with pure gas, for example $CO_2,\;N_2$ and so on, they did not found the characteristics of microcellular foaming process with one more gases. If one more gases inlet the resin, the characteristics of microcellular foaming process is changed very amazingly. In this paper, discuss on the characteristics of microcellular foaming process wi th gas cocktail about cell morphology.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.29 no.5
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• pp.222-228
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• 2019

In this study, we carried out the experiment to prepare lithium carbonate powder through gas-liquid reactions with a lithium-containing solution and $CO_2$ gas using lithium hydroxide, lithium chloride, and lithium sulfate. Thermodynamically, the carbonation reaction of a lithium-containing solution showed that aqueous reaction of lithium hydroxide occurs spontaneously, but aqueous reactions of lithium chloride and lithium sulfate does not occur spontaneously. In the case of lithium hydroxide solution, the recovery rate of lithium carbonate was 69.8 % at room temperature ($25^{\circ}C$), and increased to 89.4 % at $60^{\circ}C$. In the case of lithium chloride and lithium sulfate solution, lithium carbonate could be prepared using sodium hydroxide as an additive, but the recovery rates were 19.2 % and 16.7 %, respectively.

• Microbiology and Biotechnology Letters
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• v.49 no.2
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• pp.174-180
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• 2021

Chalcones exhibit multiple biological activities. Various studies have attempted to modify the structure of chalcones with a special focus on the addition of substituents to the benzene rings. However, these chemical modifications did not improve the water solubility and bioavailability of chalcones. Glycosylation can markedly affect the physical and chemical properties of hydrophobic compounds. Here, we evaluated the ability of a highly promiscuous glycosyltransferase (GT) BsGT1 from Bacillus subtilis ATCC 6633 to biosynthesize chalcone glucosides. Purified BsGT1 catalyzed the conversion of 4'-hydroxychalcone (compound 1), 4'-hydroxy-4-methylchalcone (compound 2), and 4-hydroxy-4'-methoxychalcone (compound 3), into chalcone 4'-O-β-D-glucoside (compound 1a), 4-methylchalcone 4'-O-β-D-glucoside (compound 2a), and 4'-methoxychalcone 4-O-β-D-glucoside (compound 3a), respectively. To avoid the addition of expensive uridine diphosphate glucose (UDP-Glc), a whole-cell biotransformation system was employed to provide a natural intracellular environment for in situ co-factor regeneration. The yields of compounds 1a, 2a, and 3a were as high as 90.38%, 100% and 74.79%, respectively. The successful co-expression of BsGT1 with phosphoglucomutase (PGM) and UDP-Glc pyrophosphorylase (GalU), which are involved in the biosynthetic pathway of UDP-Glc, further improved the conversion rates of chalcones (the yields of compounds 1a and 3a increased by approximately 10%). In conclusion, we demonstrated an effective whole-cell biocatalytic system for the enzymatic biosynthesis of chalcone β-D-glucoside derivatives.

• Journal of Korean Society of Environmental Engineers
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• v.33 no.9
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• pp.677-685
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• 2011

The reverse osmosis membrane processes have several operational problems. Fouling by inorganic scale occurs on membrane surface due to increases in concentrations over solubility by retaining ions on feed side of the membrane. Inorganic scales could be controlled by antiscalants or acid addition. In this study, three antiscalants having different characteristics were selected and evaluated on efficiency of $CaCO_3$ scale control. The $CaCO_3$ scale was inhibited by the antiscalants : 0.4 mg/L for SHMP, 0.6 mg/L for Spectra Guard, and 3 mg/L for Flocon 150 N. Increasing concentration factors of simulated sea water resulted in increases in antiscalant doses for the scale control. The increases in doses were positively proportional to the concentrate factors used in this study. Spectra Guard, one of the polyacrylate type antiscalants, was the most effective to control $CaCO_3$ scale. The antiscalants with the different scale inhibition time and doses implied the different control mechanisms.