• Proceedings of the Materials Research Society of Korea Conference
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• 2007.11a
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• pp.64.2-64.2
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• 2007

• Proceedings of the Korean Society of Rheology Conference
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• 2001.06a
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• pp.7-10
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• 2001

• Journal of Environmental Science International
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• v.8 no.4
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• pp.479-483
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• 1999

Nitrifier consortium immobilized in polyvinyl alcohol was used for the removal of ammonia nitrogen from synthetic aquaculture water in the airlift bioreactor. At the aeration rate fo 0.15 vvm and bead packing volume fraction of 20%, airlift bioreactor was operated effectively for a removal of ammonia nitrogen and for a stability of operation. Ammonia nitrogen removal rate by airlift bioreactor was continuously increased with decreasing hydraulic residence time. At the HRT(hydraulic residence time) of 0.3 hour, ammonia nitrogen removal rate was 84.3 g/$m^3$.d and the highest ammonia nitrogen removal rate was 130.8 g/$m^3$.d when HRT was 0.1 hour.

• Proceedings of the Korea Concrete Institute Conference
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• 2008.04a
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• pp.1009-1012
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• 2008

The fiber dispersion performance in fiber-reinforced cementitious composites is a crucial factor with respect to achieving desired mechanical performance. However, evaluation of the fiber dispersion performance in the composite PVA-ECC(Polyvinyl alcohol-Engineered Cementitious Composite) is extremely challenging because of the low contrast of PVA fibers with the cement-based matrix. In the present work, an enhanced fiber detection technique is developed and demonstrated. Using a fluorescence technique on the PVA-ECC, PVA fibers are observed as green dots in the cross-section of the composite. After capturing the fluorescence image with a Charged Couple Device(CCD) camera through a microscope. The fibers are more accurately detected by employing a series of process based on a categorization, watershed segmentation, and morphological reconstruction.

• Journal of the Korean Applied Science and Technology
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• v.20 no.4
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• pp.353-357
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• 2003

Sodium azide (SA) is commonly used as propellant for inflating automatic safety bags and other chemical manufacturing purposes. The investigation of potentially thermal hazard of sodium azide and its mixture with polymers are very important because it can occur an expected traffic accident so we took a experiment s using different scanning calorimeter (DSC) in nitrogen atmosphere. The decomposition temperature were about $350{\sim}450^{\circ}C$. We could find not only exothermic reaction was remarkably decreased in mixture s of acrylonitrile-butadiene-styrene (ABS) and polyvinyl chloride (PVC), but also increasing mixed rate of ABS, polyvinyl alcohol (PVA) and polymethyl methacrylate (PMMA) decreased thermal decomposition heat.

• Analytical Science and Technology
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• v.18 no.2
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• pp.97-103
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• 2005

The various size and morphology microcapsules were prepared to produce smell sweet by heating condensation reaction of melamine and formaldehyde using 5-types of surfactants such as the laurylbenzenesulfonic acid sodium salt (SDS), polyvinylpyrrolidon (PVP), polyvinyl alcohol (PVA), Span-80 and 2-acrylamido-2-methyl-1-1 propanesulfonic acid (AMP). As result it was found that the size and morphology of microcapsule is intimately associated with a kind of surfactants. In order to prepare microcapsule with antibacterial, the silver nanoparticle was prepared by gamma-irradiation. microcapsule with silver nanoparticle was prepared.

• Membrane Journal
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• v.23 no.3
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• pp.237-244
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• 2013

We fabricated several composite membranes with selectively permeable performance designed to facilitate water vapor transport and resist DMMP vapor permeation. Materials for selective permeable membrane were based on polyvinyl alcohol and functional polymer containing basic functional group. With these materials, we characterized selectively permeable performance to identify next-generation material with chemical-biological protective capability. Results showed that polyvinyl alcohol (PVA)/polyethyleneimine (PEI) materials possessed performance with superior water vapor permeation ($2,200{\sim}2,900g/m^2/day$) and protective capability against DMMP vapor ($47g/m^2/day$).

• Korean Chemical Engineering Research
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• v.56 no.1
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• pp.139-142
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• 2018

Silicon (Si) is a promising anode material for next-generation lithium ion batteries (LIBs) because of its high capacity of 4,200 mAh/g ($Li_{4.4}Si$ phase). However, the large volume expansion of Si during lithiation leads to electrical failure of electrode and rapid capacity decrease. Generally, a binder is homogeneously mixed with active materials to maintain electrical contact, so that Si needs a particular binding system due to its large volume expansion. Polyvinyl alcohol (PVA) is known to form a hydrogen bond with partially hydrolyzed silicon oxide layer on Si nanoparticles. However, the decrease of its cohesiveness followed by the repeated volume change of Si still remains unsolved. To overcome this problem, we have introduced the electrospinning method to weave active materials in a stable nanofibrous PVA structure, where stresses from the large volume change of Si can be contained. We have confirmed that the capacity retention of Si-based LIBs using electrospun PVA matrix is higher compared to the conservative method (only dissolving in the slurry); the $25^{th}$ cycle capacity retention ratio based on the $2^{nd}$ cycle was 37% for the electrode with electrospun PVA matrix, compared to 27% and 8% for the electrodes with PVdF and PVA binders.

• Korea-Australia Rheology Journal
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• v.20 no.2
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• pp.73-77
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• 2008

The rheological properties of polar solutions are very sensitive to preparative methods as well as measuring conditions. The effects of dissolution temperature on the rheological properties of the solutions of polyvinyl alcohol (PVA) in dimethyl sulfoxide were investigated over the range of dissolution temperatures $70-130^{\circ}C$. Viscosity was increased as dissolution temperature was increased. PVA solutions prepared at 120 and $130^{\circ}C$ showed Bingham behavior, which became less noticeable with decreasing dissolution temperature. The modified Cole-Cole plot of the solutions gave slope less than 2, suggesting the solutions were a heterogeneous system irrespective of optical transparency. Further, the slope was decreased with increasing dissolution temperature, indicating that the solid character got more prominent as dissolution temperature was increased. However, the relaxation time of the solutions was little dependent on dissolution temperature.

• Journal of the Korean Society for Advanced Composite Structures
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• v.6 no.4
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• pp.58-63
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• 2015

The purpose of this experimental research is to evaluate the workability and strength properties of hybrid fiber reinforced concrete containing amorphous steel fiber and organic fiber. For this purpose, the hybrid fiber reinforced concrete containing amorphous steel fiber(ASF) with polyamide(PA) and polyvinyl alcohol(PVA) fiber, respectively were made according to their total volume fraction of 0.5% for water-binder ratio of 33%, and then the characteristics such as the workability, compressive strength, and flexural strength of those were investigated. It was observed from the test results that the workability and compressive strength at 7 and 28 days were decreased and the flexural strength at 7 and 28 days was increased with increasing ASF and decreasing organic fiber.