• Proceedings of the Korean Magnestics Society Conference
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• 2008.12a
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• pp.18.2-18.2
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• 2008

• KCI Concrete Journal
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• v.13 no.2
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• pp.42-48
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• 2001

The bend resistance of coated reinforcing bar is greatly influenced by both the adhesion strength between bar and coating materials, and the followed transformation of coating material as bars bend. Especially, tearing state or partial microscopic cracks are predicted on the inside and outside of bending angle, because tensile strength and elongation of polymer film are very different according to types of polymer dispersions in bar coating, and these damaged parts are rapidly corroded by penetration of corrosive factors. In this study, polymer cement slurry coated reinforcing bars with various polymer dispersions are prepared by following combined conditions, polymer-cement ratio of 50% and 100%, coating thickness of 250$\mu$m and 450$\mu$m, coating number, curing age of 3, 7, 14 and 28days. Then the specimens are tested for working life and bend resistance at bending angles $90^{\circ}$, $135^{\circ}$and $180^{\circ}$ to observe the microscopic damage effect as the bars bend. Also, epoxy-coated reinforcing bars for control experiment were used with 250$\mu$m of coating thickness. The tensile strength for polymer films is performed. From the test results, the working life of the polymer cement slurry is within 90 seconds. Among four types of polymer dispersion, polymer cement slurry coated reinforcing bar using St/BA-1 emulsion has the excellent bend resistance, which is remarkably improved than that of epoxy-coated reinforcing bar. And the bend resistance is more related to elongation than tensile strength of polymer film. Polymer cement slurry with a polymer-cement ratio of 100%, a coating thickness of $450\mu$m and one coating using St/BA emulsion is selected as a most suitable coating material for coated reinforcing bar.

• 한국정보디스플레이학회:학술대회논문집
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• 2004.08a
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• pp.1216-1219
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• 2004

LC and polymer miscibility in HPDLC has been studied in terms of solubility parameter. It was found that better grating formation and diffraction efficiency were obtained when the difference in solubility parameters between polymer and LC is greater.

• 한국정보디스플레이학회:학술대회논문집
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• 2004.08a
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• pp.1212-1215
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• 2004

Diffraction modes of holographic grating were fabricated with polyurethane acrylates(PUA). Two types of silica (AEROSIL 200 and AEROSIL R812) were added to reduce the shrinkage of polymer matrix. It was founded that shrinkage of PUA composite film was reduced with the addition of silica. HPDLC based PUA/silica composite also showed high diffraction efficiency. The morphology of the resultant gratings was analyzed by using scanning electron microscopy(SEM) and Tg of the polymer matrix by dynamic mechanical thermal analysis(DMTA).

• Proceedings of the Polymer Society of Korea Conference
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• 2006.10a
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• pp.292-292
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• 2006

A two-step process of the solution blending and the subsequent melt mixing in a Brabender mixer was used to prepare clay nanocomposites of SAN/PVC and of ABS, respectively. It was found that the new method was effective in obtaining well-dispersed nanocomposites for both cases. The glass transition behavior of the organoclay nanocomposites were analyzed by using theoretical equations. The interaction characteristics were evaluated by using the solubility parameters estimated from the group molar attraction constants.

• Proceedings of the Polymer Society of Korea Conference
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• 2006.10a
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• pp.336-336
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• 2006

The present work is focused on the synthesis of a series of fully aliphatic polyimides and the incorporation of adamantane moieties and siloxane groups to them and studies the deviation in the basic traits of the fully aliphatic polyimides. In this work, we wish to discuss how adamantyl group and siloxane moieties influence the basic properties of aliphatic polyimides (APIs), by synthesizing various fully aliphatic polyimides and polyimidesiloxanes (APISiO).

• 한국정보디스플레이학회:학술대회논문집
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• 2003.07a
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• pp.516-519
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• 2003

We modified the molecular structure of urethane acrylate oligomer by varying raw materials. Also fluorination of the host polymer matrices has been found to influence the morphological and the electrooptical properties of the resulting HPDLC grating. The incorporation of fluorinated monomers in HPDLC formulation enhance the LC phase separation and improved elctro-optical properties.

• Proceedings of the Polymer Society of Korea Conference
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• 2006.10a
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• pp.187-187
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• 2006

A new type solid polymer electrolyte (SPE) composed of poly (vinyl alcohol) (PVA) and lithium trifluoromethanesulfonate ($LiCF_{3}SO_{3}$) was prepared by means of the solution cast technique to observe that Li ion can move by ion hopping decoupled from polymer segmental motion inside of the 'fast cationic transport process'. The highest ion conductivity of the SPEs obtained from ac impedance measurements was $1.42{\times}10^{-3}S/cm$ at room temperature for SPE with 80wt% of salt concentration. Using LSV, we found that the SPEs had good electrochemical stabilities and using FT-IR and AFM, we found the formation of network-like structure.

• 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.

• Proceedings of the Membrane Society of Korea Conference
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• 2005.05a
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• pp.93-94
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• 2005