• Applied Biological Chemistry
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• v.35 no.1
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• pp.30-35
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• 1992

Two strains J2W and J2Y which were isolated from soil can utilize polyvinyl alcohol(PVA) as a sole carbon source. PVA was utilized symbiotically by the mixed culture of these two strains which could not utilize PVA in each respective pure culture. Effect of degree of PVA polymerization on the its utilization was examed, and there was remarkable difference among three kind of PVA(PVA 500, 1500 and 2000). The reconstruction of there two strains was carried out with other symbionts Pseudomonas sp. PW and Pseudomonas sp. G5Y which were able to utilize PVA. PVA utilization occured in each remixed culture of J2Y strain with Pseudomonas sp. PW J2W strain with Pseudomonas sp. G5Y, respectively. Identification of bacteria was based on morphological and biological chatacteristics, J2W and J2Y strain were similar to a strain of Pseudomonas pseudimallei and Xanthomonas campestris, respectively.

• Microbiology and Biotechnology Letters
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• v.20 no.1
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• pp.96-101
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• 1992

Two strains of polyvinyl alcohol (PVA) utilizing bacteria were isolated from the waste water and soil. These strains, G5Y and PW, were able to utilize PVA symbiotically as a carbon source, but could not utilize PVA separately. In the mixed culture of these strains, 0.5 percent of PVA was almost completely degraded in 3 days. Effect of degree of PVA polymerization on the its utilization was examined, and there was no remarkable difference among three kind of PVA (PVA 500, 1500, a d 2000). These bacteria were able to utilize PV,4 in the desizing waste water of factory as well as enrichment PVA medium. These strains, C5Y and PW, were identified as Pseudomonas cepucia and Pseudomonus pseudomallei, respectively, based on morpholofical and biological characteristics.

• KSBB Journal
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• v.10 no.3
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• pp.241-248
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• 1995

For the treatment of poorly biodegradable polyvinyl alcohol(PVA) in dye-processing wastewater, immobilized microbial beads were prepared by uslng agar-acrylamide method. PVA removal efficiency for the synthetic wastewater was 85% at the PVA volume loading rate of $3.1g/\ell$.day. In case of real desizing wastewater, PVA removal efficiency was 81.3% at the PVA volume loading rate of $3.25g/\ell$.day. In observation of cross section of immobilized bead passed 5 months with diameter of 2.4mm, the growth of cell was limited by the resistance of substrate and oxygen transfer for the inners region of more than 48% of bead radius from the surface. It was estimated that 70% of total removed PVA was degraded by the immobilized cells in the continuous immobilized reactor. Substrate utilization rate in the suspended reactor was decreased with increasing dilution rates above 0.083 hr-1, but that in the immobilized reactor was increased with increasing dilution rates up to 0.125hr-1. The substrate removal efficiency of immobilized reactor was much superior to that of suspended reactor with increasing dilution rates. Saturation constant of substrate utilization rate equation, Ks was $6.6 g PVA/\ell$, and maximum specific substrate utilization. k was 0.175g PVA/g cell.hr

• Journal of the Korean Wood Science and Technology
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• v.39 no.3
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• pp.197-205
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• 2011

Cellulose nanofibrils (CNF) with 50~100 nm diameter were manufactured from micro-size cellulose by an application of a high-pressure homogenizer at 1,400 bar. High strength nanopapers were prepared over a filter paper by a vacuum filtration from CNF suspension. After reinforcing and dispersing CNF suspension, hydroxypropyl cellulose (HPC) and polyvinyl alcohol (PVA)-based composites were tailored by solvent- and film-casting methods, respectively. After 2, 4, 6 and 8 passes through high-pressure homogenizer, the tensile strength of the nanopapers were extremely high and increased linearly depending upon the pass number. Chemical modification of 1H, 1H, 2H, 2H-perfluorodecyl-triethoxysilane (PFDTES) on the nanopapers significantly increased the mechanical strength and water repellency. The reinforcement of 1, 3, and 5 wt% CNF to HPC and PVA resins also improved the mechanical properties of the both composites.

• Advances in concrete construction
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• v.11 no.2
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• pp.111-126
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• 2021

Concrete cracking due to brittle tension strength significantly prevents fully utilization of the materials for "flexural-shear failure" type shear walls. Theoretical and experimental studies applying fiber reinforced concrete (FRC) have achieved fruitful results in improving the seismic performance of "flexural-shear failure" reinforced concrete shear walls. To come to an understanding of an optimal design strategy and find common performance prediction method for design methodology in terms to FRC shear walls, seismic performance on shear walls with PVA and steel FRC at edge columns and plastic region are compared in this study. The seismic behavior including damage mode, lateral bearing capacity, deformation capacity, and energy dissipation capacity are analyzed on different fiber reinforcing strategies. The experimental comparison realized that the lateral strength and deformation capacity are significantly improved for the shear walls with PVA and steel FRC in the plastic region and PVA FRC in the edge columns; PVA FRC improves both in tensile crack prevention and shear tolerance while steel FRC shows enhancement mainly in shear resistance. Moreover, the tensile strength of the FRC are suggested to be considered, and the steel bars in the tension edge reaches the ultimate strength for the confinement of the FRC in the yield and maximum lateral bearing capacity prediction comparing with the model specified in provisions.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2008.11a
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• pp.199-203
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• 2008

With recent trend in domestic and global market requiring architectures' conversion into skyscrapers seasoned with the features of landmarks, structural problems in relation with explosive spatting during fire emergencies are arising as controversial issues. Accordingly, many productive researches have been made in relation to the reinforcement techniques for improving fire resistance and the number of applications in the field is gradually increasing. In this study, a ductile outline form using ECC (Engineered Cementations Composites) was made with improvements on the structure and fire resistance to examine its applicability. Also, currently in Japan, the number of studies and applications is increasing focusing on reduction of construction time and improvement of workability with application of Half-PCa method. However, using such method of construction, large structural members decrease the utilization of space and architecture-wise, there is a disadvantage of the weight increase. Therefore, in such context, it would be worth reducing the weight of the structural members by reducing the size using ECC. In addition, its excellent pseudo strain-hardening due to fiber may have great effects on seismic designs. In the mean time, this study planned 3 equal conditions for mix water, PVA fiber and additives excluding binder and refractory to evaluate the mechanical properties of resistance against pressure and internal force. Finally, an evaluation was executed on the fire resistance of the newly made ductile outline form. As a result, from ECC-I to ECC-III, all showed excellent mechanical properties due to pseudo strain-hardening and in the fire resistance test conducted with ISO 834 heating curve, most of them tended to be in the range of the reference temperature (538℃-180min), so there was no occurrence of any explosive spatting.

• Journal of Korean Society of Forest Science
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• v.109 no.1
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• pp.41-49
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• 2020

In this study, the effect of seed pre-treatments and pellet coating materials to enhance the efficiency of large-scale propagation of Aster koraiensis seeds were investigated. Seeds were immersed in water for one day, and only those that sank were used for pre-treatment to use filled seeds. Pre-treatments were divided into hormone treatments, with gibberellic acid (GA₃; 200 and 500 ppm) and 24-epibrassinolide (10^-6, 10^-7, and 10^-8M), and priming with potassium nitrate (100 mM of KNO₃). To produce pellet-coated seeds, pellet materials (DTCS or DTK) were applied to control (unprimed) and primed seeds with binders (PVA or CMC). The maximum germination percent (GP) of seeds before pellet coating was 65% (with the priming treatment), and there was no difference in the GP of seeds among hormone treatments. For seeds sown in a growth chamber on filter paper, GP was 41% for control (unprimed/uncoated) seeds, 65% for uncoated primed seeds, 71% for DTCS/PVA-pellet-coated seeds, and 42% for DTK/CMC-pellet-coated seeds. Seeds that were primed first and then pellet-coated showed greatly improved GP, mean germination time (MGT), and germination rate than seeds that were only pellet-coated. For seeds sown in commercial soil in a greenhouse, control seeds had a GP of 27%, whereas primed seeds had the highest GP (58%), and their MGT and GT were 9.4 days and 7.0%·day, respectively. In addition, DTK/PVA-pellet-coated seeds (40%) also had a GP higher than the control (27%), and their MGT was 15-27 days. For seeds sown in sandy-loam soil in a greenhouse, unprimed-pellet-coated seeds and primed-pellet-coated seeds both had GPs ranged of 39%, which were lower than that of control seeds. In general, the seeds that were pellet-coated with DTK had a higher GP than those pellet-coated with DTCS. Furthermore, the MGT of unprimed-pellet-coated seeds was 15.0-19.8 days, which was longer than the MGT of primed-pellet-coated seeds. These results suggest that priming enhances seedling emergence of Aster koraiensis seeds. Moreover, when priming is combined with pellet coating, DTK is a more suitable pellet material than DTCS, and PVA and CMC are equally suitable adhesives.

• Journal of the Korean Wood Science and Technology
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• v.48 no.4
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• pp.431-449
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• 2020

Structural property of most hydrogels is soft, resulting in low mechanical performance that limits their usage in the biomedical applications. For overcoming the drawback, cellulose nanocrystals (CNCs) were adopted in this study. Effects of CNCs on characteristics and drug delivery performance of poly (vinyl alcohol) based hydrogels were explored. FT-IR results showed that the fabricated hydrogels had semi-IPN (semi-interpenetrating polymer network) by formation of acetal and aldehyde bridge. Water absorption and swelling ratio decreased with increasing CNCs content, and the hydrogels with CNCs showed better viscoelastic performance than the without CNCs. Also, CNCs mostly improved the ability of the hydrogel to absorb the drug and the sustainability of the drug release. These results demonstrated that incorporating CNCs into the hydrogel systems can be a good alternative to improve drug delivery performance and mechanical property of the hydrogels.