• Proceedings of the Membrane Society of Korea Conference
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• 1993.10a
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• pp.52-53
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• 1993

투과증발 분리를 위하여 여러가지 막 소재와 공정을 개발하기 위한 노력이 다방면에서 이루어지고 있으며, 이에 관한 자료도 많이 제시되고 있으나 고분자 분리막의 개발은 아직도 미흡한 상태이다. 한편 투과증발 분리는 공정자체는 매우 간단하면서도 분리막의 투과성능에 따라 분리효율이 달라지기 때문에 여러종류의 막의 개발이 필요하다. 따라서 본 연구에서는 물/유기용제 혼합액에서 물을 분리하기 위하여 친수성이 강한 두 고분자 재료인 poly(vinyl alcohol)(PVA)와 carboxymehtylcellulose(CMC)를 브랜드하여 목적하는 분리기능을 갖는 새로운 막을 제조하여, 물/유기용제, 혼합액의 분리특성을 브랜드비와 온도 및 농도 그리고 분리시간에 따라 각각 검토하였다.

• Korean Journal of Materials Research
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• v.16 no.3
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• pp.145-150
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• 2006

Various colors of light emitting diodes(LED) and four-band white light sources are obtained using a violet LED and various phosphor films. $BaMg_2Al_{16}O_{27}:Eu\;(blue),\;SrGa_2S_4:Eu\;(green),\;and\;Eu(TTA)_3(PTA)$ (red) phosphors are dispersed in poly-vinyl-alcohol aqueous solutions, and phosphor films are prepared by coating the suspensions to PET film. The narrow band emission of $Eu(TTA)_3(PTA)$ phosphor has excellent red luminescent property for four-band white light excited by the violet LED.

• Journal of the Korean Graphic Arts Communication Society
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• v.20 no.1
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• pp.65-78
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• 2002

The suspension polymerization of styrene was carried out to obtain the narrow-size distribution of particle by using poly(vinyl alcohol) (PVA) as suspension stabilizer according to the degree of hydrolysis and the molecular weight. The stabilizing properties of suspension are also dependent on the interfacial tension of aqueous solution when PVA is added. When the polymerization process was carried out with low hydrolyzed PVA, it gave single, well-defined particles, while high hydrolyzed PVA gave clusters. The size of particle produced in this study ranged between 5${\mu}{\textrm}{m}$ and 10${\mu}{\textrm}{m}$. The suspending agent, PVA, influences on the drop size and drop stability, When the molecular weight of PVA is increased, the drop size decreases and the drops become more stable toward coalescence. An increase in the PVA concentration decreases the mean drop size and narrows the drop size distribution.

• Proceedings of the Polymer Society of Korea Conference
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• 2006.10a
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• pp.168-168
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• 2006

Low-operating voltage organic field-effect transistors (OFETs) have been realized with high dielectric constant (${\kappa}$) polymer such as cyanoethylated poly vinyl alcohol (CR-V, ${\kappa}=12$). Since the $high-{\kappa}$polymers are likely to contain water and ionic impurities, large hysteresis and considerable leakage current are frequently observed in OFETs. To solve these problems, we cross-linked the CR-V by using a cross-linking agent. Cross-linked CR-V dielectrics showed high dielectric constant of 11.1 and good insulating properties, resulting in a high capacitance ($81nF/cm^{2}$ at 1MHz) at 120 nm of dielectric thickness. Pentacene FETs with cross-linked CR-V dielectrics exhibited high carrier mobility ($0.72\;cm^{2}/Vs$), small subthreshold swing (185 mV/dec) and little hysteresis at low-operating voltage (${\Leq}-3V$).

• Proceedings of the Membrane Society of Korea Conference
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• 1996.10a
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• pp.45-46
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• 1996

기존의 기체분리 방법과 비교해 볼때 막분리법은 에너지 효율이 높으며 기체를 연속적으로 분리할 수 있다는 장점을 갖고있다. 그러나 막분리법으로 기체를 분리할 경우 기체분리에 사용되는 고분자막은 고온에 약하기 때문에 상용 기체분리막을 제조하는데 사용되는 고분자의 종류는 매우 제한되어 있다. 이러한 기존의 고분자 막이 갖는 물성을 개선하기 위한 방법으로 고분자를 블렌드 시킴으로서 고분자의 기체투과 특성 및 물성을 향상시키려는 연구가 여러 연구자들에 의해 진행된 바 있다. Paul은 고분자를 블렌드시켜 막을 제조하여 기체분리에 적용한 연구에서 블렌드막이 각각 단일 고분자로 제조한 막과는 다른 물성을 나타내며 고분자와 고분자 사이의 상호작용으로 인해 막의 기체투과 특성뿐만아니라 기계적 물성에도 영향을 준다고 보고한 바 있다. 이에 본 연구에서는 Na-alginate와 PVA 등의 수용성 고분자를 사용하여 블렌드막을 제조하고 제도된 막을 대상으로 물성 및 기체투과 특성에 대해 연구함으로써 Na-alginate/PVA 블렌드가 막 물성 및 기체투과 특성에 미치는 영향에 대해 연구하고자 하였다.

• Proceedings of the Korea Concrete Institute Conference
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• 2006.05b
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• pp.385-388
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• 2006

In this study, I examined hardening and non-hardening of the DFRCC (Ductile Fiber Reinforced Cementitious Composites) according to maximum size of coarse aggregate and the diameter of PVA (Poly Vinyl Alcohol) to develope PVA fiber reinforced concrete with the feature of DFRCC. As a result of this study, the fresh properties is similar regardless of maximum size of coarse aggregate. The bending stress and bending stress-displacement of DFRC showed big differences according to maximum size of coarse aggregate and diameter.

• Proceedings of the Korea Concrete Institute Conference
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• 2006.05b
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• pp.405-408
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• 2006

The purpose of this study was to determine the optimum length distribution of hybrid PVA(Poly vinyl alcohol) fiber. To produce blended PVA fiber length, first the length distribution of PVA fiber in the cement composites were identified in an experimental study based on simplex lattice design. Among the different length distributions investigated, fiber length was found to have statistically significant effect on plastic shrinkage cracking of cement composites. Subsequently, Complex analysis techniques were used to devise an experimental program that helped determine the optimum combinations of the selected fiber length distribution based on plastic shrinkage crack. The optimum blended PVA length ratio was 0.0146% 4mm fiber, 0.0060% 6-mm fiber, 0.0285% 8-mm fiber, and 0.0209% 12-mm fiber.

• Proceedings of the Korea Concrete Institute Conference
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• 2006.05b
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• pp.337-340
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• 2006

Utilize several kinds of reinforcement fibers to control workability and surface crack in occasion of mortar used in dilapidated concrete section repair public law. Polypropylene or poly vinyl alcohol that is hydrophilic fiber etc. is used much usually with this reinforcement fiber. Reinforcement fiber does important action that control crack that enhances coherence between material and happens at dry contraction. In this study, wished to use Sepiorite that inorganic materials and affinity such as cement are excellent nature inorganic world fiber and improve repair mortar performance. In this study, as reinforcement fiber, wished to grasp physical characteristics that uses Sepioraiteu and happens this time and grasp application possibility of concrete's repair mortar.

• Journal of the Korean Ceramic Society
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• v.52 no.1
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• pp.56-60
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• 2015

Discontinuous, polycrystalline $Al_2O_3$-dispersed TZP fibers were prepared by the centrifugal spinning of a colloidal $ZrO_2$ sol containing Y and Al nitrates and poly(vinyl alcohol). Factors affecting the rheological properties of the sols, such as sol concentrations, aging, and the amounts and types of additives, were investigated by measuring the shear viscosities. The flow characteristics of the sols were studied in relation to the spinnability by measuring the viscosity with respect to the shear rate. The spinnability was obtained through the addition of a polymer which increases the viscosity to a range of optimum viscosity values for spinning. Aging the sols containing the additives did not noticeably change the sol viscosities at room temperature up to 30 days. The flow behavior of the spinnable sols progressively changed from nearly Newtonian to pseudoplastic with an increase in the sol concentration.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.19 no.12
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• pp.1160-1166
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• 2006

Maxwell-displacement-current (MDC) measuring technique has been applied for the investigation of monolayers of poly(vinyl alcohol)s bearing azobenzene side-chains (6Az5PVA) mixed with p-pentyl-p'-cyano-biphenyls (5CBs) on a water surface. For mixed monolayers containing trans-form 6Az5PVA and LCs, displacement current due to photo isomerization was not generated with alternative photo-irradiation with UV and svisible light. In contrast, for mixed monolaters containing cis-form 6Az5PVA and LCs, displacement current was generated. Finally, it was found that the alignment layers deposited in cis-form could photoregualte the orientation of LCs.