• Journal of the Korean Ceramic Society
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• v.36 no.1
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• pp.97-105
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• 1999

In the binary system of SiC and carbon, porosity and pore size distribution of green body was controlled by varying pH, by the addition of polyelectrolyte dispersants, and by using different particle size of starting powders. The preforms having different green microstructure were fabricated by slip casting from suspensions having different dispersion condition. The reaction bonding process was carried out for these preforms. The condition of reaction bonding was 1600$^{\circ}C$ and 20 min. under vacuum atmosphere. The analyses of optical and SEM were studied to investigate the effect of green microstructure on that of reaction bonded silicon carbide and subsequently the mechanical properties of sintered body was investigated. Different green microstructures were obtained from suspensions having different dispersion condition. It was found that the pore size could be remarkably reduced for a fine SiC(0.5$\mu\textrm{m}$). The bimodal microstructure was not found in the present study, which is frequently observed in the typical reaction bonded silicon carbide. It is considered that the ratio between SiC and C was responsible for the formation of bimodal microstructure. For the preform fabricated from the well dispersed suspension, the 3-point bending strength of reaction-bonded silicon carbide was 310${\pm}$40 MPa compared to the specimen fabricated from relatively agglomerated particles having lower value 260${\pm}$MPa.

• Korean Chemical Engineering Research
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• v.53 no.3
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• pp.302-308
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• 2015

Isothermal vapor liquid equilibria for the binary system of 3-methylpentane with ethylene glycol monopropyl ether ($C_3E_1$) and ethylene glycol isopropyl ether ($iC_3E_1$) were measured at 303.15, 318.15, and 333.15K. In our previous work, phase equilibria for the binary system of $C_3E_1$ mixtures were investigated according to the chain length of alkane, alcohol or those isomer. But in this study, we discussed the different effect of $C_3E_1$ and its isomer, $iC_3E_1$, on the phase equilibria. The measured systems were correlated with a Peng-Robinson equation of state (PR EOS) combined with Wong-Sandler mixing rule for the vapor phase, and NRTL, UNIQUAC, and Wilson activity coefficient models for the liquid phase. All the measured systems showed good agreement with the correlation results. And it was found that the phase equilibria showed very little difference between the $iC_3E_1$ mixture system and the $C_3E_1$ mixture system.

• Journal of the Korean Chemical Society
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• v.36 no.6
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• pp.914-918
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• 1992

The preferential transport phenomena of neutral cation-anion moieties in neutral macrocycle-facilitated emulsion liquid membrane were described in this study. Emulsion membrane systems consisting of (1) aqueous source phase containing 0.001M $M(NO_3)_2$ (M = $Mn^{2+}$, $Co^{2+}$, $Ni^{2+}$, $Cu^{2+}$, $Zn^{2+}$, $Sr^{2+}$, $Cd^{2+}$, $Pb^{2+}$) (2) a toluene membrane containing 0.02M ligand (DB$N_3O_2$, DB18C6) and the surfactant span 80 (sorbitan mono oleate) (3% v/v) and (3) aqueous receiving phase containing $Na_2S_2O_3$ or $NaNO_3$ were studied with respect to the disappearence of metal ions from the source phase as a function of time. Cation transport rates for various two component equimolar mixture of metal ions were determinded. $Cd^{2+}$ was transported higher rates than the other $M^{2+}$ in the mixture solution.

• Journal of the Society of Cosmetic Scientists of Korea
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• v.30 no.2
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• pp.189-195
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• 2004

Carbon black have not been used as pigment material in cosmetic because of very low density and dispersity, but carbon black have applicable character as black pigment because of non-toxic, stable physico-chemical property, and black colority. In this study, mesoporous silica samples were synthesized by sol-gel reaction using surfactants-template method; TEOS (tetraethoxysilane) - a) PEO/lecithin, b) PEO/polyethylene glycol, c) lecithin/polyethylene glycol in ethanol/water solution. Synthesized organic-inorganic hybrid - silica were heat-treated in N2 condition at 500$^{\circ}C$. Mesoporous silica with black carbon in pore have the effective density and show the good dispersity in both hydrophilic and hydrophobic solvent. Properties of the samples were measured; specific surface area (750㎡/g) and pore size (4-6nm) using BET, pore structure (cylindrical type) using XRD, morphology (spherical powder with 0.1-0.5$\mu\textrm{m}$ partical size) of the samples using SEM. Carbon-silica black color applied to mascara, it shows a dark black colority and good dispersity as compared with the general black color titania pigment. Moreover, it is possible to control the density of black color pigment because it is possible to control pore volume and particle size of mesoporous silica properly. It show the good volume effects in mascara. That is why possible to apply all kinds of cosmetic products.

• Journal of the Society of Cosmetic Scientists of Korea
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• v.35 no.2
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• pp.79-89
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• 2009

The objective of this study was to find out the stable formulation of nano-emulsion containing high concentration of quercetin and to investigate the effect of an ethanol on the nano-emulsion prepared by POE (30) hydrogenated castor oil (HCO-30)/oil/quercetin/ethanol/water system. Nano-emulsion was prepared using emulsion inversion point (EIP) method as low-energy method plus homogenizer as high-energy method. To evaluate effect of ethanol and other components on the nano-emulsion, physical properties such as droplet size, morphology, and size distribution were determined. The optimal quercetin concentration was 0.2 % on the nano-emulsion. The droplet diameter was below 300 nm at the HCO-30 concentration below 2.00 %. Nano-emmulsion containing 4.75 % HCO-30 was the most stable and its mean droplet size was 172.40 nm. Finally, the size of nano-emulsion containing 4.00 % ethanol was 128.15 nm and size distribution was also narrow. The results showed that the breakdown process of this nano-emulsion could be attributed to Ostwald ripening. This study about effect of ethanol on the nano-emulsion showed that loading capacity of drug could be increased by using a small amount of ethanol. As prepared stable nano-emulsion, this study showed that these results could be applied to pharmaceutics, cosmetic including skin-care products, perfume and etc.

• Journal of the Korean Chemical Society
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• v.37 no.3
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• pp.327-333
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• 1993

A method was developed for the determination of trace elements in seawater by precipitate flotation preconcentration and subsequent flame atomic absorption detection. In order to quantitatively coprecipitate trace ions such as Cd(II), CuI(II), Fe(III), Mn(II), Pb(II) and Pd(II), 2.0 ml of 1.0M cerium(III) solution was added to 1.0l of seawater and the pH was adjusted to 9.5 with 5.0 M sodium hydroxide solution while stirring with a magnetic stirrer. The precipitate was floated with the aid of surfactant solution (1.0 ml of 0.3% sodium oleate) by bubbling nitrogen gas through a porous (No. 4) fritted glass disk. The floats was collected in a small Erlenmeyer flask by suction. The washed precipitate was dissolved in 8.0 M nitric acid and marked with deionized water in the volumetric flask of 10.0 ml. The analyte was determined by measuring the atomic absorbances in 100-fold concentrated solution. Above all analytes in Kangnung (East Sea) and Kanghwado (West Sea) sea waters were found to be under the detection limit of this method. The recoveries of over 92% for all analytes spiked into seawater samples showed that this method was applicable to the analysis of real seawater.

• Journal of the Society of Cosmetic Scientists of Korea
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• v.41 no.2
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• pp.113-119
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• 2015

The measurement of hydration level in the surface layer of the skin, stratum corneum (SC), gives important information on the biophysical properties and function of the skin barrier such as softness, flexibility, and healthiness of the skin. But it is difficult to measure a consistent hydration level from a sample to another sample due to individual variations and environmental changes. The aim of this study was to evaluate objective hydration after using various products in the SC. The SC Hydration was measured by capacitance (Corneometer$^{(R)}$, C+K, Germany) on the ventral site of forearm from 40 healthy volunteers. The skin surface was chronologically measured immediately after application of the test products and 3 and 6 hours later. We analyzed the averages of five measurements of each site and used the hydration increase rate for correction on untreated site variation. We found that most polyols including glycerol and butylenes glycol influenced directly the hydration increase rate in the SC previously. In this study, glycerol was used to prepare the standard products from 0 to 20 percents and applied to the same volunteers. The individual standard curve showed linear relation to glycerol concentrations. Based on the the standard curve, hydration of SC was converted into hydration increase rate to glycerol concentrations. The converted glycerol concentrations of products were repetitive and reproducible. In addition, the individual standard curve was used to relate the skin type of each individual. These results suggest that the hydration of the SC standardized regardless of external variation and individual skin condition can explain detailed skin state variation. Further studies will be conducted with other ingredients such as surfactants, lipids and aqueous materials, and with other methods for noninvasive measurement.

• Journal of the Society of Cosmetic Scientists of Korea
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• v.39 no.1
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• pp.55-63
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• 2013

Applications of nano-emulsion for cosmetics as a means of promoting dermal absorption have been the subject of interest. In this study, the stability of nano-emulsions prepared by low-energy emulsification method and varying the composition of raw materials was investigated. By measuring the particle size of the nano-emulsion against time, the stability of nano-emulsions prepared by adding polyol to water phase was increased significantly compared with the nano-emulsions prepared by adding polyol to ethanol phase. The speed of adding ethanol phase to water phase did not have a significant impact on the particle size and stability. Depending on the type of oil, stability was not affected. However, there would be a correlation between the initial size of the nano-emulsion droplets and the molecular weight and polarity of the oil. Stability and the initial particle size according to the type of polyols showed a similar trend except 1,2 hexanediol. The initial droplet size was affected by the concentration of surfactant and oil. However, the initial droplet size did not change against time. Concentration of ethanol was observed to have a significant impact on the initial particle size and stability.

• Korean Journal of Food Science and Technology
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• v.35 no.4
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• pp.591-597
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• 2003

To compare the quality of genomic DNA extracted from potato for PCR detection, four different methods, such as silica-based membrane method, silica-coated bead method, STE solution treatment, and CTAB-phenol/chloroform method, were evaluated. Also, to remove an excessive carbohydrate from the potato, ${\alpha}$- and ${\beta}$-amylase were used individually and in combination. When used both silica-based membrane method and silica-coated bead method combined with enzymes, the genomic DNAs were extracted from the raw potato with high purity for PCR. However, the silica-coated head method combined with enzyme treatment was the most efficient for extraction of the genomic DNA from the frozen fried potatoes. When applied with STE solution, the highly purified DNA was extracted from the raw potatoes without enzyme treatment in adequate yield for PCR. In cases of processed potatoes, such as frozen-fried potato and fabricated potato chips, CTAB-phenol/chloroform method is mostly feasible for DNA extraction and PCR efficacy at high sensitivity. As the results of PCR amplification, 216bp of PCR product was detected on 2% agarose gel electrophoresis, but any amplicons derived from New leaf and New leaf Y gene was not detected in any sample.

• Korean Journal of Microbiology
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• v.45 no.4
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• pp.354-361
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• 2009

This study was carried out to develop an effective biocarrier-mediated bioaugmentation technology which will be useful for remediation of the crude oil-contaminated marine sediments. Enrichment of several microbial communities was made from several oil-polluted seashore sites and the two distinctively functional consortia have been successfully selected. These two consortia were grown together and used to manufacture the microbial agents for bioaugmentation of marine sediments polluted with crude oil. The most dominant species in the mixed culture was identified as Alcanivorax borkumensis based on pure culture and DGGE analysis. Bioaugmentation of oil-polluted marine sediments with the microbial agent MA-2 formulated using the mixed culture and biocarriers (activated carbon and minerals) was more effective, especially in combination with an oxygen producing (releasing) compound (ORC). Ninty percent of TPH was removed in the presence of ORC in 35 days while 74% in the absence of ORC. This indicated that the indigenous consortial degraders could be immobilized on the active carbon as a biocarrier to manufacture microbial agents and then effectively bioaugmented for remediation of the oil-polluted sediments.