• Korean Journal of Optics and Photonics
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• v.10 no.6
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• pp.494-499
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• 1999

We report on the results of holographic transmission grating that can be controlled by the applied AC electric field. We have fabricated a polymer-dispersed liquid crystal material that composed of multifunctional acrylate monomer blended with the liquid crystal mixture E7. To investigate an electro-optic properties of fabricated HPDLC, diffraction efficienties (DE) are measured as a fuction of applied electric field and density of liquid crystal. Maximum DE of about 70% is obtained about 30 wt% of LC concentration at a zero field. We have also shown that optical image was recorded in the tllm, and then the reconstructive image was switchable with the applied electric fields. ields.

• KIEE International Transactions on Electrophysics and Applications
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• v.11C no.3
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• pp.91-95
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• 2001

Reflective holographic polymer dispersed liquid crystal(HPDLC) device has a multilayer structure consisting of alternate layers of polymer and liquid crystal droplets. Periodic modulation of a refractive index reflects light of a specific wavelength in accordance with Braggs law. Samples cured isotropically were illuminated with an Argon-ion lase at 514nm. We optimized the reflcetion efficiency of HPDLC as a function of monomer functionality, LC composition and irradiation intensity. The properties of the HPDLC films were observed by UV-visible spectroscopy. We found that the maximum reflection efficiency depends on the monomer functionality, LC composition, and laser intensity. We expect these films could be used in full-color reflective display by stacking them to obtain a mixture of colors.

• Polymer(Korea)
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• v.34 no.1
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• pp.14-19
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• 2010

Applying acrylic silane monomer for determent of weathering damage of stone cultural assets from various sources was investigated to improve inorganic affinity of polymer impregnated to the stone for conservation treatment using impregnation of acrylic polymers under pressure. Radical polymerization was carried out with various mixture ratios of methacrylate (MMA), as the base monomer, and vinyl trimethoxy silane (VTMS). Subsequently, according to the changes of glass transition temperatures, average molecular weights, and storage moduli of the obtained copolymers, the case of adding 1 wt% of benzoyl peroxide, polymerization for 8 hrs, and mixing 5 mol% of VTMS to MMA was the optimum condition of monomer ratio and polymerization. Practically, fresh granites collected in domestic site and weathered stones were treated by following the obtained result above, and then, the moisture absorption, impact, acid resistance, and adhesion properties of the treated stones were compared to those of the corresponding stones treated with MMA only. It was found that those properties of the stones treated with PMV5 were considerably improved.

• Journal of IKEEE
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• v.21 no.1
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• pp.24-29
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• 2017

In this paper, we have developed the nano carbon tile and chip which is based on a reducing process of oxidation and the viscous fluid control, after hardening to the stylene monomer and methylol acrylamide monomer using an acrylic emulsion junction material. Then we can obtain the sphere form structure of diagonal 1~3 mm, they have mixture the acrylic emulsion junction material(45%) and the coconut carbon powder(55%) of size 300~500 mesh for 25~30 min. Finally, if we have dry for the formated carbon including 30~90 minute at $90{\sim}300^{\circ}C$, then be obtained for pure carbon formation of 95%. In order to identify the safety of the friendly circumstance carbon formation, we have tested the far-infrared ratio, energy analysis, gas density and anti-disease germs experiment.

• Journal of the Korean Graphic Arts Communication Society
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• v.16 no.3
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• pp.15-27
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• 1998

Several aspects of polymer dispersed liquid crystal(PDLC) film properties make them interesting for display application. Most versions of PDLC materials are able to modulate light without the use of polarizers, which offers advantages in optical throughput(brightness) and viewing angle compared to polarizer-based display. In this papers, we attemped to doe minimum of remaining liquid crystals at polymer network for the liquid crystal-polymer composite (LCPC) films. In results, best phase separation behaviors turned out liquid crystal/monomer/oligomer mixture system.

• Bulletin of the Korean Chemical Society
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• v.17 no.6
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• pp.525-528
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• 1996

Seven cali[4]arenes, having two different substituents in AAAB or AABB pattern at the upper rim of calix were synthesized by fragmentation condensation reaction of p-substituted phenol trimer (AAA) with 2,6-bishydroxymethylated 4-substituted phenol (B) or that of dimer (AA) with 2,2'-bishydroxymethylated dimer (BB). An equimolar mixture of the coupling components (trimer and monomer or dimer and dimer) was refluxed in dioxane in the presence of TiCl4to afford calix[4]arene 6 and 7 in 15-38% yield. The structure of calix[4]arenes was confirmed by elemental analysis and the 1H/13C NMR spectroscopy.

• Journal of Biomedical Engineering Research
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• v.23 no.6
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• pp.451-458
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• 2002

Osteoporosis is a systemic skeletal disease caused by low bone mass and the decrease of bone density in the microstructure of trabecular bone. Drug therapy(PTH Parathyroid hormone) may increase the trabecular thickness and thus bone strength. Vertebroplasty is a minimally invasive surgery foy the treatment of osteoporotic vertebral compression fracture. This Procedure includes Puncturing vertebrae and filling with Polymethylmethacrylate(PMMA). Although altering recommended monomer-to-Powder ratio affects material properties of bone cement, clinicians commonly alter the mixture ratio to decrease viscosity and increase the working time. The Purposes of this study were to analyze the effect of 4he monomer-to-powder ratio on the mechanical characteristics of trabecular. In this paper, the finite element model of human vertebral trabecualr bone was developed by modified Voronoi diagram, to analyze the relative effect of hormone therapy and vertebroplasty at the treatment of osteoporotic vertebrae. Trabeuclar bone models for vertebroplasty with varied monomer-to-Powder ratio(0.40∼1.07 ㎖/g) were analyzed. Effective modulus and strength of bone cement-treated models were approximately 60% of those of intact models and these are almost twice the values of hormone-treated models. The bone cement models with the ratio of 0.53㎖/g have the maximum modulus and strength. For the ratio of 1.07㎖/g, the modulus and strength were minimum(42% and 49% respectively) but these were greater than those for drug therapy. This study shows that bone cement treatment is more effective than drug therapy. It is found that in vertebroplasty, using a monomer-to-powder ratio different from that recommended by manufacturer nay significantly not only reduce the cement's material Properties but also deteriorate the mechanical characteristics of osteoporotic vertebrae.

• Macromolecular Research
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• v.15 no.5
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• pp.403-411
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• 2007

Monodisperse micron-sized polystyrene (PS) spheres were successfully obtained using a single stage soap-free emulsion method in aqueous media mixed with ethanol (co-solvent) containing NaCI as the electrolyte. The optimum conditions for preparing the monodisperse PS microspheres, using soap-free emulsion polymerization in a water/ethanol mixture with an electrolyte, were studied. The presence of the co-solvent and electrolyte controlled the particle dispersion stability during the polymerization. The microspheres formed using PS, with a weight-average diameter of $2.6{\mu}m$, coefficient of variation of 5.3% and zeta potential of -15.1 eV, were successfully obtained in the presence of 0.1 wt% NaCI, 10 wt% monomer, 0.1 wt% initiator and 95/5 (g/g) of a water/ethanol mixture reacted at $70^{\circ}C$ for 24 h.

• Journal of the Korean Applied Science and Technology
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• v.27 no.3
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• pp.240-248
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• 2010

The blending effects of surfactants on the polystyrene emulsion polymerization were studied. The blending of Triton X-100 and SDS affects to the interfacial properties of the styrene monomer and water phases, and finally, the properties of the polystyrene latex particles. As the blending ratio of SDS/Triton X-100 increases, the interfacial tension and CMC of the blended surfactants were decreased and results in a reducing the size of the latex particles. It was found that the interfacial tension was reduced when the surfactant were blended. By increasing the SDS content, the interfacial tension was reduced, and, at a certain condition, the interfacial tension was reached to an extremely low value to form micro-emulsion and the nano-sized latex particles (80~110 nm).

• Applied Chemistry for Engineering
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• v.9 no.3
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• pp.348-354
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• 1998

Cellulose grafted with acrylic acid(AAc) was prepared by radiation grafting technique. The effects of reaction temperature. reaction time, monomer concentration, and the crosslinkers on the AAc grafting reaction on cellulose were examined. The amount of AAc grafted on the cellulose reached maximum at the concentration of 0.75vol% difunctional crosslinker and 1.0vol% trifunctional crosslinker, respectively. In the presence of acid, the amount of AAc grafted on the cellulose was decreased when reaction solution contains difunctional crosslinker, while that was increased when reaction solution contains trifunctional crosslinker. In the grafting reaction of cellulose with AAc and TMETA, mixture containing ferrous sulfate and acid enhanced further AAc grafting yield than mixture containing ferrous sulfate only.