• Korean Journal of Materials Research
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• v.26 no.6
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• pp.320-324
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• 2016

Porous SiC beads were prepared by freeze-drying a polycarbosilane (PCS) emulsion. The water-in-oil (w/o) emulsion, which was composed of water, PCS dissolved p-xylene, and sodium xylenesulfonate (SXS) as an emulsifier, was frozen by dropping it onto a liquid $N_2$ bath; this process resulted in 1~2 mm sized beads. Beads were cured at $200^{\circ}C$ for 1 h in air and heat-treated at $800^{\circ}C$ and $1400^{\circ}C$ for 1 h in an Ar gas flow. Two types of pores, lamella-shaped and spherical pores, were observed. Lamellar-shaped pores were found to develop during the freezing of the xylene solvent. Water droplets in the w/o emulsion were changed into spherical pores under freeze-drying. At $1400^{\circ}C$ of heat-treatment, porous SiC was synthesized with a low level of impurities.

• Korean Journal of Food Science and Technology
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• v.30 no.5
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• pp.1114-1119
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• 1998

The stabilities of O/W emulsions (lipophilic core material:lipophobic wall material=3:2, w/w) containing various kinds of emulsifiers were compared to determine the optimal conditions of the HLB (hydrophilic lipophilic balance) value, the concentration and composition of emulsifier, the ratio of core material to the wall material, and the concentration and composition of polymers in the wall material. The effect of different chemical types of emulsifiers and the influence of single vs. binary emulsifier systems were compared with 13 kinds of emulsifier HLB values of $0.6{\sim}16.7$ at the concentration of 0.50%(w/w). The emulsion system was stable (more than 99.0 of ESI value) when the HLB value of the emulsifier was more than 11.0 or less than 2.8 of emulsifier HLB value. But it was unstable (less than 40.0 of ESI value) at the HLB value of the emulsifier between 3.4 and 8.6. Especially, we could find out the emulsion containing the emulsifier of polyglycerol polyricinoleate (PGPR, HLB 0.6) became stable creamy state. And, the ESI value of binary emulsifier system containing 0.25%(w/w) of PGPR and 0.25%(w/w) of polyoxyethylene sorbitan monolaurate (PSML, HLB 16.7) was higher than that of any single emulsifier system at the concentration of 0.50%(w/w). The highest emulsion stability was obtained in the liquefied wall material composed of 0.25%(w/v) of waxy corn starch and 0.50%(w/v) of agar.

• Journal of the Society of Cosmetic Scientists of Korea
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• v.21 no.1
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• pp.19-37
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• 1995

A fine oil -in-water (O/W) emulsion using non-aqueous emulsification technique was developed. And the behaviors of POE(25)octyldodecyl ether in non-aqueous polyol/oil systems were studied by observing the surface tension, interfacial tension, turbidity and transition temperature. It was found that POE(25)octyldodecy1 ether hardly existed as the micelle in the non-aqueous polyol system while, in water, it formed micelles very easily. So, when a polyol, like glycerine in which POE(25)octyldodecyl ether has a poor solubility, was added, POE(25)octyldodecyl ether moved to the surface. After saturated at surface, POE(25)octyldodecyl ether began to precitate. The mean particle size of the final emulsion was 230nm. Also, the emulsion system was stable at 0$^{\circ}C$, 25$^{\circ}C$, 40$^{\circ}C$, 50 $^{\circ}C$ and freeze-thaw cycle chamber for a month, while a conventional emulsion system was unstable. It is concluded that, by pertinent combination of polyols, we can improve the adsorption efficiency of surfactant.

• Journal of the Korean Applied Science and Technology
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• v.29 no.3
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• pp.377-392
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• 2012

It has been known that small solid particles act as a stabilizer in pickering emulsion system. In this study, we successfully prepared stable pickering emulsion in n-hexylalcohol and water system with $TiO_2$ whose surface was treated by alkylsilane. The optimum condition to prepare pickering emulsion stabilized by $TiO_2$ particles was determined by amount of $TiO_2$ particles and ratio of water and oil phase. The type of pickering emulsion was dependent on wettability of particles for water and n-hexylalcohol. When the amount of $TiO_2$ particles increased up to 5.00 wt%, the stability of pickering emulsion was showed to be improved. The most stable pickering emulsion was prepared in the case of W/O type which has the ratio of oil and water phase (3 : 7). We tried to prepare porous $SiO_2-TiO_2$ composite pigments using a pickering emulsion as template at the optimal condition. Porous pigments were synthesized with Ludox HS-30 as an inorganic material by sol-gel process. The characteristics and shape of porous pigments were measured by optical microscope, SEM, BET, XRD and EDS.

• Applied Chemistry for Engineering
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• v.34 no.3
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• pp.299-306
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• 2023

In this study, the O/W emulsification processes with the natural surfactants that were extracted from Medicago sativa L. and Sapindus saponaria L. as emulsifiers were optimized using the central composite design-response surface methodology (CCD-RSM). Herein, independent parameters were the amounts of mixed emulsifiers, the mixing ratio of natural emulsifiers (soapberry saponin/alfalfa saponin), and the emulsification time, whereas the reaction parameters were the emulsion stability index (ESI), mean droplet size (MDS), and antioxidant activity (DPPH radical scanvenging activity). Through basic experiments, the ranges of operation variables for the amount of mixed emulsifiers, the mixing ratio of natural emulsifiers, and the emulsification time were 12~14 wt%, 30~70%, and 20~30 min, respectively. The optimum operation variables deduced from CCD-RSM for the amount of mixed emulsifiers, the mixing ratio of natural emulsifiers, and the emulsification time were 13.2 wt%, 44.2%, and 25.8 min, respectively. Under these optimal conditions, the expected values of the ESI, MDS, and antioxidant activity were 88.7%, 815.5 nm, and 38.7%, respectively. And, the measured values of the ESI, MDS, and antioxidant activity were 90.6%, 830.2 nm, and 39.6%, respectively, and the average experimental error for validating the accuracy was about 2.1%. Therefore, it was possible to design an optimization process for evaluating the O/W emulsion process using CCD-RSM.

• Korean Journal of Food Science and Technology
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• v.35 no.3
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• pp.423-428
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• 2003

Stabilities of W/O emulsions containing eugenolchitosan (EuCs) prepared from chitosan and eugenol were compared to determine the optimal conditions for the ratio of water (core phase) to corn oil (continuous phase), the concentration of EuCs, storage temperature, and the extent of homo-mixing. The optimal ratio of water to corn oil was 2:3 (w/w). The effects of EuC concentrations, and singular vs. binary system of emulsifiers on the storage stability of the emulsion were investigated with EuCs and polyoxyethylene sorbitan monolaurate. The emulsion was stable, showing more than 95% emulsion stability index (ESI) value, when the concentration of EuCs was more than 0.18% (w/v). ESI value of binary emulsifier system was almost equal to that of singular emulsifier system at the concentration of 0.18% (w/v). At this singular emulsifier system, the W/O emulsion formed by EuCs had ESI value of 100%. The optimal concentration of EuCs was determined as 0.18% (w/v). The highest stability of the emulsion was obtained from the homo-mixing at 11,000 rpm for 10 sec and the storage temperature ranging $25{\sim}65^{\circ}C$. EuCs produced from this study was mutagenecity-negative on Ames test and contained no heavy metal ions.

• KSBB Journal
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• v.26 no.4
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• pp.333-340
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• 2011

In this study, gemcitabine-loaded methoxy poly(ethylene glycol)-b-poly(L-lactide) (MPEG-PLLA) microparticles with different PEG block lengths were prepared by a W/O/W double emulsion technique. The present study focuses on the investigation of the influence of various preparative parameters such as the ratio of internal water phase and oil phase, polymer concentration, solvent composition of organic phase and salt concentration of external water phase on the morphology and encapsulation efficiency of the microparticles. The microparticles fabricated at high volume ratios of internal water phase to oil phase and at high polymer concentrations showed a relatively high encapsulation efficiency and low porosity. When a dichloromethane/ethyl acetate mixture was used as solvent, both the encapsulation efficiency and drug loading of the microparticles decreased as the level of ethyl acetate increased. The addition of a salt (NaCl) to the external water phase significantly improved the encapsulation efficiency up to 40%, and the microparticles became more spherical with their size and porosity decreased.

• Korean Chemical Engineering Research
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• v.52 no.6
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• pp.789-795
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• 2014

Acetic acid is the most abundant and serious ethanol fermentation inhibitor in dilute-acid hemicellulosic hydrolysates. A mixture of xylose, acetic acid and sulfuric acid was chosen as a simulated hemicellulosic hydrolysate so as to find an optimal separation system to selectively remove acetic acid from the hydrolysates. In order to attain the purpose, emulsion liquid membrane was applied to removal of acetic acid from the simulated hemicellulosic hydrolysate. The effects of main constituents of water-in-oil (W/O) emulsion, such as amine extractant type, surfactant composition, additive type, and type and concentration of stripping agent, on extraction of acetic acid, xylose, and sulfuric acid in the simulated hemicellulosic hydrolysate were investigated. Under specific experimental conditions, degree of extraction of acetic acid was higher than 95% while loss of xylose was insignificant, which means that the current emulsion liquid membrane can be an economically feasible process.

• Applied Chemistry for Engineering
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• v.7 no.1
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• pp.145-152
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• 1996

A fine oil-in-water (O/W) emulsion using nonaqueous emulsification technique was developed and the behaviors of POE(25)octyldodecyl ether in nonaqueous solvent/oil systems were studied by observing the surface tension, interfacial tension, turbidity and transition temperature. It was found that POE(25)octyldodecyl ether existed soluble in nonaqueous solvent while, in aqueous system, it formed micelles. So, when a solvent, like glycerine in which POE(25)octyldodecyl ether has poor solubility, was added, POE(25)octyldodecyl ether moved to the surface. After saturated at surface, POE(25) octyldodecyl ether began to precitate. The mean particle size of the final emulsion was 230nm. Also, the emulsion system was stable at 0, 25, 40, $50^{\circ}C$ and cycling test for a month, while the conventional emulsion system showed unstability. It is concluded that, by pertinent combination of solvents, the adsorption efficiency of surfactant could be improved.

• Journal of the Society of Cosmetic Scientists of Korea
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• v.43 no.4
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• pp.273-279
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• 2017

In this study, low viscous O/W (oil-in-water) nano-emulsion with fatty acid and fatty alcohol was prepared by phase inversion emulsification method using Tween 80 and Span 80 widely used in cosmetic products. The particle size of the nano-emulsion was increased as increasing the concentration of fatty alcohol in oil phase. Adjusting the HLB of mixed surfactants, a stable nano-emulsion with a narrow size distribution was produced. Similar change in viscosity and electrical conductivity in both systems containing fatty acid and fatty alcohol was shown in the vicinity of the phase inversion point. However, high viscosity was shown in a wide range of different aqueous fraction unlike the system consisting only oils and surfactants. The low viscous nano-emulsion with less than 100 nm droplet size was stable for one month or more at room temperature. O/W nano-emulsions with low viscosity containing fatty acid or fatty alcohol produced by low-energy emulsification method can be widely used as formulations of cosmetics.