• Journal of the Society of Cosmetic Scientists of Korea
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• v.20 no.1
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• pp.64-81
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• 1994

O/W emulsions with mixed nonionic surfactants(polyoxyethylene(20)sorbitan monostearate/sorbitan sesquioleate), liquid paraffin, water prepared by direct inversion emulisification method and continuous inversion emulsification Method. The one-step, two-step and three-step phase inversion emulsification method were used in experiments. Effect of added water on droplet size of final O/W emulsions which is prepared by phase inversion emulsification method were investigated. In direct inversion emulsification method(two-step emulsification method), fine and homogeneous droplets of OIW emulsions were formed after phase inversion steps i.e. ,W/O - (W/O) If double emulsion - O/W emulsion. In continuous inversion emulsification method(three-step emulsification method), fine and homogeneous O/W emulsion were formed after phase inversion steps i.e., W/O - pseudomicroemulsion - O/W. By latter method, more Fine and homogenuous droplets were formed than former method. 10-10, 8 HLB region of mixed non-ionic surfactants could produce most fine droplets. This HLB region had maximum values of solubilization water and This HLB value of mixed nonionic surfactants produced fine and homogenuous droplets.

• Journal of the Society of Cosmetic Scientists of Korea
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• v.42 no.2
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• pp.127-133
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• 2016

In this study, water-in-oil (W/O) nanoemulsions of water/Span 80-Nikkol BL 25/oil system were prepared by the PIC method at elevated temperature. This method allows the formation of finely dispersed W/O nanoemulsions with low viscosity in this system. However, macroemulsions rather than nanoemulsions were prepared by PIC method at room temperature. As a result of the significant change of interfacial tension with temperature, the emulsion droplet size decreases from $2{\mu}m$ to 100 nm with the increase in temperature from $30^{\circ}C$ to $80^{\circ}C$. The droplet size of nanoemulsions prepared at $80^{\circ}C$ was in the range of 50 ~ 200 nm and the internal phase content could reach as high as 15 wt%. The most stable nanoemulsion was formed in the vicinity of 7.0 of optimum HLB of the emulsifier mixture. The obtained nanoemulsions were stable without obvious change in droplet size in one month. This study provides valuable information for optimizing the formation of W/O nanoemulsions with low viscosity. These results suggest that W/O nanoemulsions of low viscosity could be useful for cosmetics with soft feeling.

• Journal of the Korean Ceramic Society
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• v.21 no.3
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• pp.221-230
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• 1984

In this study an investigation was made to determine optimum ratio between $SO_3$, MgO and $K_2O$ that maximizes $C_2S$ formation in Clinkering reaction Using response surface analysis method. It was proved that 1) Residual $K_2O$ int he clinker should be converted to $K_2SO_4$ because $K_2SO_4$ has less effect on the burnability than $K_2O$, 2) Optimum ratio if $SO_3$/K2O is 1.5, 3) Optimun balance between $CaSO_4$ and MgO is to be adjusted to such a level that w/o SO3=0.7(w/o MgO-2).4) In case of lack of $K_2O$ free CaO was minimized when $K_2SO_4$=2.3w/o and MgO=1.5w/o but if remaining $K_2O$ was 2w/o free CaI was minimized in the level that $K_2SO_4$=2.3w/o and MgO =1.5 w/o but if remaining $K_2O$ was 2 w/o free CaO was minimized in the level that $K_2SO_4$=4.5w/o and MgO =3.0 w/o.

• Journal of Pharmaceutical Investigation
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• v.28 no.3
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• pp.159-164
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• 1998

The O/W and W/O emulsions containing Scutellariae Radix extract(SRE) which is very slightly soluble in oil phases and sparingly soluble in water phases, were prepared by homogenizing water and oil phases with emulsifier. The diameters of emulsion were ranged from 100 to $300\;{\mu}m$. The viscosity of W/O emulsion was higher than that of O/W emulsion. W/O emulsion was more stable than O/W emulsion which was gradually degraded when tested by centrifuge method and temperature tolerance method at $50^{\circ}C$. The antibacterial activity of two emulsions was not significantly different from that of aqueous solution of SRE, and showed similar MIC and bacterial growth inhibition rate.

• Journal of Pharmaceutical Investigation
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• v.35 no.1
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• pp.33-38
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• 2005

Recently increasing attention has been focused on solid lipid nanoparticles (SLN) as a parenteral drug carrier due to its numerous advantages that can come from both polymeric particle and fat emulsions, together with the possibility of controlled release and increasing drug stability. Lipophilic drugs such as paclitaxel, cyclosporin A, and all-trans retinoic acid have been successfully entrapped in SLN but the incorporation of hydrophilic drugs in SLN is very limited because of their very low affinity to the lipid. Therefore, as a new approach to improve the loading of hydrophilic drugs, a w/o/w emulsion technique has been developed. The primary objective of the current study was to improve the loading efficiency of a model hydrophilic drug, glycine (Log P = -3.44) into SLN. The proposed preparation process is as follows: A heated aqueous phase consisting of 0.1 ml of glycine solution in water (100 mg/ml), and poloxamer 188 (5 mg) were then added to a molten oil phase containing precirol (100 mg) and lecithin (5 mg). This mixture was dispersed by sonicator, leading to a w/o emulsion. A double emulsion (w/o/w) was formed after the addition of 2% poloxamer solution to the above dispersed system. After cooling the double emulsion, solid lipid nanosuspensions were successfully formed. The lipid nanoparticles had the mean particle size of 441.25 nm, and the average zeta potential of -20.98 mV. The drug loading efficiency was measured to be 8.54% and the drug loading amount was measured to be 0.92%. The w/o/w emulsion method showed an increased loading efficiency compared to conventional o/w emulsion method.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2008.11a
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• pp.237-238
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• 2008

The films of Vanadium tungsten oxide, $V_{1.85}W_{0.15}O_5$, were grown on Pt/Ti/$SiO_2$/Si substrate by RF sputtering method. The $V_{1.85}W_{0.15}O_5$ thin films deposited on Pt/Ti/$SiO_2$/Si substrates by RF sputtering method exhibited fairly good TCR and dielectric properties. It was found that film crystallinity, dielectric properties, and TCR properties were strongly dependent upon the annealing temperature. The dielectric constants of the $V_{1.85}W_{0.15}O_5$ thin films annealed at $300^{\circ}C$ were 55, with a dielectric loss of 1.435, respectively. Also, the TCR values of the $V_{1.85}W_{0.15}O_5$ thin films annealed at $300^{\circ}C$ were about -3.6%/K.

• Journal of Pharmaceutical Investigation
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• v.37 no.4
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• pp.211-216
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• 2007

The bark of Alnus japonica has been used for the treatment of fever, hemorrhage and diarrehea in oriental traditional medicine. Recently, it was revealed that the diarylheptanoids from the bark of Alnus japonica possess anti-inflammatory activity and are expected to be applicable for atopic dermatitis. In this study, oregonin, one of major active components in the bark of Alnus japonica, was developed in the form of semisolid formulations for topical delivery. Oregonin was incorporated into four ointment bases: O/W cream, W/O cream, hydrophilic ointment and lipophilic ointment. Oregonin release from all formulation prepared was evaluated. Franz cell method and immersion method were employed to characterize the release patterns of drug from each formulation based on solvent availability. O/W cream showed a better release profile than the other formulations when evaluated with Franz cell method with an order of O/W cream, hydrophilic ointment, W/O cream and lipophilic ointment. In the immersion method, hydrophilic ointment showed the greatest release rate at times 1 hour exceeding compared to other bases with an order of hydrophilic ointment, O/W cream, W/O cream and lipophilic ointment. Hydrophilicity and solvent availability of formulation seems to significantly influence the release rate of oregonin from ointment bases. In this study, we successfully characterized the oregon in ointment and found that o/w cream is a promising formulation for the topical delivery of oregonin.

• Journal of Microbiology and Biotechnology
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• v.14 no.4
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• pp.673-679
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• 2004

A microbial cryoprotectant formulation using a W/O/W multiple emulsion system was developed. The psychrotolerant microorganism, B4, isolated from soil in South Korea, was observed by the drop freezing method, in which the microorganism sample inhibited ice nucleation activity. The antifreeze activity was eliminated when the microorganism sample was treated with protease, indicating that the antifreeze activity was due to the presence of antifreeze protein. The result of the l6S rDNA sequencing indicated the B4 strain was most closely related to a species of the genus Bacillus. Culture broth of B4 strain (Bacillus sp.) and rapeseed oil containing 1 % polyglycerine polyricinolate (PGPR) were used as core and wall material, respectively. The most stable W/O emulsion was prepared at a core/oil ratio of 1:2. The highest W/O/W emulsion stability was achieved when the primary emulsion to external aqueous phase containing 0.5% caster oil polyoxyethylene ether $(COG25^{TM})$ ratio was 1:1. Microcrystalline cellulose showed better W/O/W emulsion stability than other polymer types. The viability of cells in a W/O/W emulsion was higher than free cells during storage at $37^\circ{C}$. An acidic pH and UV exposure decreased the viability of free cells, but cells in W/O/W emulsion were more stable under these conditions.

• Journal of Energy Engineering
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• v.2 no.2
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• pp.194-199
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• 1993

Gas diffusion passes are introduced to catalyst layer so as to enlarge reaction region in cathode and anode and then improve electrode performances. The catalyst layer was manufactured with PTFE/carbon (none catalyst loaded) for gas diffusion and Pt/carbon (10 w/o Pt catalyst loaded) by varing the mixing ratio of (PTFE/carbon) to (Pt/carbon) by catalyst powdering method. The electrodes made by mixing Pt(10 w/o)/carbon powders and PTFE/carbon powders containing 60 w/o PTFE at the ratio of 7 : 3 showed the best electrode performances. It was known that by comparing the porosities to electrode performances the electrode performances were increased as both macro pore for gas diffusion and micro pore for electrolyte intrusion were formed much more. The platinum catalyst content in electrode was 0.2 mg/$\textrm{cm}^2$ and the PTFE content was 42 w/o. The electrode performance in unit cell was 220 ㎃/$\textrm{cm}^2$/0.7 V at operating temperature of 150$^{\circ}C$.

• Proceedings of the KIEE Conference
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• 2008.10a
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• pp.121-122
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• 2008

The films of the vanadium tungsten oxide, $V_{1.85}W_{0.15}O_5$, were grown on Pt/Ti/$SiO_2$/Si substrate by RF sputtering method. It was found that film crystallinity, dielectric properties, and TCR properties were strongly dependent upon the thin film thickness. As increasing of $V_{1.85}W_{0.15}O_5$ thickness, the grain size, morphology, and crystallinity increased. The dielectric constants of $V_{1.85}W_{0.15}O_5$ thin films deposited at 150nm were 71.11, with a dielectric loss of 0.015, respectively. Also, The $V_{1.85}W_{0.15}O_5$ thin films showed good TCR values of -3.45%/K.