• Journal of the Society of Cosmetic Scientists of Korea
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• v.24 no.3
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• pp.111-115
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• 1998

We investigated the stability of all-trans-retinol on the liquid crystalline O/W emulsion composed of mainly alkyl polyglycerine, alkyl polyglucose and glycerine, and compared the activity of all-trans-retinol in the various forms of liquid crystal. Under certain conditions, novel liquid crystalline gel was formed around oil droplets, and layers of this liquid crystalline gel were very wide and rigid. (SWLC; Super Wide Liquid Crystal) SWLC was very helpful to stabilize retinol in O/W emulsion. After storage at 45 C for 4 weeks, all-trans-retinol in O/W emulsion composed of SWLC retained above 85% of the activity upon HPLC analysis, whereas those within no liquid crystalline emulsion gave 47% and normal liquid crystalline emulsion composed of fatty alcohols gave 40 60%. Retinol in oil phase is nealy insoluble in pure water, but in cosmetic emulsion systems can be slightly solubilized into water because emulsifiers and polyols in emulsion systems function as solubilizers. In this case, water in outer phase acts as a media for oxygen transporation$.$and thus destabilizes retinol. As a result, retinol in O/W emulsion has a tendency to become unstable. SWLC surrounding oil droplet which contains retinol is wide and rigid, therefore reduces contact between inner phase and outer phase To make SWLC, properties of emulsifiers are very important phase transition temperature should be high, and the structure of surfactants should be bulky, and their ratio should be suitable to make rigid and wide liquid crystalline gel layer in order to reduce contact between retinol in inner phase and water in outer phase.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.28 no.7
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• pp.439-445
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• 2015

We established the emulsion method using membrane filter with precise control of LC droplet distribution in PDLC. PDLC cells with various LC droplet size distributions such as single droplet sizes of $1.0{\mu}m$, $1.9{\mu}m$ and $3.5{\mu}m$, the mixture of two different LC droplet sizes and the mixture of three different LC droplet sizes were fabricated and the electro-optical properties of the emulsion type PDLC cells with various droplet size distribution were investigated. In the appropriate droplet size range, the PDLCs with the single droplet sizes distributions have good electro optical properties than those with the mixture of three different LC droplet sizes. In addition, the PDLC cells with the mixture of two different LC droplet sizes have the better electro optical properties than those with single droplet sizes distribution. The PDLC cell with dual droplet size distribution of $1.0+1.9{\mu}m$ shown the best electro optical properties than the PDLC cells with other size distributions. This method enabled us to find the proper LC droplet size distribution for achieving both high transmittance and contrast ratio.

• Proceedings of the Polymer Society of Korea Conference
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• 2006.10a
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• pp.218-218
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• 2006

A number of new ideas have been implemented to control the droplet morphology and electrooptic properties of holographic polymer dispersed liquid crystal (HPDLC). Doping of conductive fullerene particles to the conventional HPDLC induced dual effects of reducing both droplet coalescence and operating voltage. Chain transfer agent gave higher gel content with lower crosslink density, less dark reactions and less grating shrinkage with much smooth LC-polymer interfaces. Addition of octanoic acid (OA) to the formulation of HPDLC gave a decrease in droplet size and monotonic increase of the off state diffraction throughout the OA content.

• Journal of the Korean Applied Science and Technology
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• v.21 no.4
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• pp.279-288
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• 2004

Liquid crystal (LC) system was introduced into W/O emulsion in order to enhance the stability and moisturizing effect. The LC system, composed of beeswax, surfactant, and water was formed on the surface of emulsion droplet, which was investigated through a polarized microscope. The phenomenon that the viscosity in W/O emulsion system is decreased with time, was reduced by the formation of LC with the addition of beeswax. Centrifugal separation test showed that the stability of emulsion system was increased with the addition of beeswax to 3%. The color change of vitamin C was delayed in LC emulsion systems, which indicates stabilization effect against the oxidation of vitamin C. Evaporation rate in W/O emulsion was retarded by LC, so that high moisturizing effect is expected in W/O LC system.

• Journal of the Optical Society of Korea
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• v.18 no.6
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• pp.753-761
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• 2014

We propose a two-step UV irradiation procedure to fabricate polymer-dispersed liquid crystal (PDLC) films by lamination. During the first UV treatment, before lamination, the UV-curable monomers coated on one film substrate are solidified through photo-polymerization as the phase separation between the liquid crystals and the monomers. Introducing an adhesion-enhancement layer on the other plastic substrate and controlling the UV irradiation conditions ensure that UV-induced cross-linkable functional groups remain on the surfaces of the photo-polymerized layers. Thereby, the adhesion stability between the top and bottom films is much improved during a second (post-lamination) UV treatment by further UV-induced cross-linking at the interface. Because the adhesion-enhancement and PDLC layers prepared by the bar-coating process are solidified before lamination, the PDLC droplet distribution and the cell gap between the two plastic substrates remain uniform under the lamination pressure. This ensures that the voltage-controlled light transmittance is uniform across the entire sample.

• 한국정보디스플레이학회:학술대회논문집
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• 2006.08a
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• pp.1394-1397
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• 2006

Polymer Dispersed Liquid Crystal (PDLC) films, of which the liquid crystal has negative dielectric anisotropy, were prepared from the phase separation between MJ001317 and a variety of compositions of resins by common polymerization induced phase separation method. In this work, the effects of resin compositions have been systematically investigated and it was found that the morphology and size of droplet, which is closely related to electro-optic properties, mainly depend on the rate of polymerization and cross-linking density for each resin composition. The reverse mode PDLC films from this newly developed formulation containing TPGDA/EHA/HMPPO showed the good off-state transmittance, contrast ratio (19/1), and relatively low driving voltage(10V).

• Journal of the Korean Applied Science and Technology
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• v.20 no.2
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• pp.101-109
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• 2003

Provitamin $B_5$ liquid crystal ($PVB_5$-LC) was the new emulsion system to enhance moisturizing activity on the skin. In this study, it should be mentioned that PVB5-LC could be prepared with the main compound of hydrogenated lecithin (HL) in oil-in water (O/W) emulsion. The key ingredient of humectants was contained 2% of provitamin $B_5$ ($PVB_5$) into the $PVB_5$-LC. The best suitable compositions of $PVB_5$-LC were made from 4.0 wt% of HL, 4.0 wt% of cetostearyl alcohol (CSA) as emulsifier and gelling agent, 3.0 wt% of 1,3-butylene glycol (1,3-BG) and 2.0 wt% of glycerin as moisturizers, 3.0 wt% of cyclomethicone (CMC), 3.0 wt% of isononanoate (ININ), 3.0 wt% of capric/caprylic triglyceride (CCTG), 3.0 wt% of macadamia nut oil (MNO) as emollients. As the analytical result of $PVB_5$-LC, it could know that the distribution range of particle size was 0.14 to 12.37 m level (mean size 3.24 m). It was certified the multi lamellar phase around the droplet of liquid crystal when observed the droplet particles through a polarization microscope. And it clinically was tested the effectiveness of moisturizing activity (in-vivo) compared with control sample (O/W emulsion). The effectiveness of moisturizing activity of $PVB_5$-LC with Skincon-200EX after 6 hours went up 49.0% (p<0.05, n=20) whereas the effectiveness of moisturizing activity of generally O/W emulsion cream was 25.7% (p<005, n=20). Also, in case of Comeometer CM-825, the moisturizing activity of $PVB_5$-LC after 6 hours rose 36.6% (p<0.05, n=20) whereas the effectiveness of moisturizing activity of generally O/W emulsion cream was 10.8%. Therefore, it was known that the effectiveness moisturizing activity of $PVB_5$-LC with HL was remarkably superior compared with O/W emulsion cream.

• Korean Chemical Engineering Research
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• v.46 no.5
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• pp.938-944
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• 2008

The electro-optic properties of polymer-dispersed liquid crystal cells containing BDVE(Butanediol vinyl ether) in PN393 base pre-polymer were examined. The higher the contents of BDVE, the smaller becomes the droplet size. However, the droplet size was saturated around $3{\mu}m$ even at 40 wt% of BDVE. Both of contrast ratio and response time of PDLC cell fabricated with a new formula were found to be superior to the reference cell with PN393 by the factor of 4.9 and 0.15, respectively. However, the new formula made the operating voltage go higher compared to the reference cell of PN393 formula. Except for contrast ratio, response time as well as operating voltage were found to be highly stabilized by adding BDVE in PN393 base pre-polymer over the temperature range of $0{\sim}60^{\circ}C$ studied.

• Journal of the Society of Cosmetic Scientists of Korea
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• v.30 no.2
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• pp.279-294
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• 2004

This study described about a liquid crystalline technology that is used in cosmetics industry. Various intermediate phases may exist between solid and liquid. At high surfactant concentration, several liquid crystalline phases can be made to have formed. Although molecular arrangement with crystallization is not regular, it is known that more relative regular state is liquid crystalline or meso-phase than liquid phase. Usually, it described in detail about manufacturing method that explained about a kind of liquid crystalline technology in cosmetics, a new liquid crystalline technology, and makes liquid crystalline. Specialty, it introduced about kind of special an emulsifier to form liquid crystalline. There were hydrogenated lecithin, ceramide, dipalmitoylhydroxyproline, DEA-cetyl phosphate, Gemini-surfactant in representative raw material to form liquid crystalline. Liquid crystalline extent that used polarization microscope to observe formation, and appears best from 400times, 600times, 1,000times well appeared. Also, droplet particle size that liquid crystal is made best 1.0-10.0$\mu\textrm{m}$ be. General emulsion more than superior result that measures the skin moisturizing effect to take advantage of liquid crystalline technology of vitamin was seen. As presence at a clinical result, wave and general emulsion more than superior result (more than 20%) that measures skin moisturizing effect about liquid crystalline of vitamin B$\_$5/ were seen (ANOMA t-test, p<0.05)

• Journal of Sensor Science and Technology
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• v.18 no.2
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• pp.154-159
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• 2009

This paper describes two methods - stamp-to-stick bonding and microtransfer molding - to integrate microfluidic channel into an optoelectrofluidic device for in-channel microparticle manipulation. We have demonstrated the optoelectronic microparticle manipulation in the channel-integrated optoelectrofluidic device using a liquid crystal display. As injecting a liquid sample containing $15{\mu}m$-diameter polystyrene particles into the fabricated channel, trapping and transport of individual microparticles have been successfully demonstrated. This channel-integrated optoelectrofluidic device may be useful for several in-channel applications based on the optoelectrofluidics such as optoelectronic flow control, droplet-based protein assay and bead-based immunoassay.