• 한국건축시공학회지
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• 제23권4호
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• pp.337-348
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• 2023

본 연구의 목적은 고유동성이 부여된 일반강도 배합 콘크리트에 대하여 요변성을 부여하여 시공정밀도가 낮은 거푸집 틈새를 통해 누출될 수 있는 모르타르나 시멘트 페이스트의 양을 저감하는 것이다. 본 연구에서는 콘크리트에 요변성을 부여하기 위해 PVA와 붕사를 사용하였다. 이에 PVA와 붕사를 사용하는 방법에 대하여 각각의 수용액을 추가하고 치환하는 방법에 따라 요변성을 포함하는 콘크리트의 성능의 변화와 거푸집의 틈새를 모사한 누출 저감 성능을 평가하였다. 본 연구에서 진행된 실험의 조건에서는 PVA와 붕사를 추가하는 방법보다는 치환하는 방법이 추가적인 물의 사용을 억제하여 재료분리 저항성과 응결 지연에서 더 양호한 콘크리트 물성을 나타내었으며 요변성의 발현 및 거푸집 누출 방지에도 효과적인 것으로 나타났다. 특히, PVA 수용액 6%를 치환하였을 때 의미 있는 수준의 거푸집 누출 감소 효과를 얻을 수 있었다. 이를 통해 PVA와 붕사를 이용하여 콘크리트 배합에 대해 요변성을 부여할 수 있다고 판단하였다. 또한 거푸집의 시공정밀도가 다소 낮은 경우에도 PVA와 붕사를 사용하여 콘크리트에 요변성을 부여함으로써 시공 품질을 확보할 수 있을 것으로 기대한다.

• 한국응용과학기술학회지
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• 제27권2호
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• pp.216-221
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• 2010

Polyvinyl acetate (PVAc) prepared by emulsion polymerization has broad applications for additive such as paint binder, adhesive for wood and paper due to its low glass transition temperature which help to plasticize substrate resins. Since emulsion polymerization has a disadvantage that surfactant and ionic initiator degrade properties of the product polymer, poly (vinyl acetate-eo-ethyl acrylate) (VAc-EA) was synthesized using potassium persulfate as catalyst and polyvinylalcohol (PVA) as protective colloid to prevent the degradation. The copolymer latex product was internally plasticized and has enhanced adhesion, water resistance during VAc-EA emulsion polymerization. No coagulation and complete conversion occur with the reactant mixture of 10 mmol/L potassium persulfate, 10 mmol/L poly ( vinyl alcohol) (PVA 17). As the concentrations of PVA increase, the viscosity becomes increase.

• 한국섬유공학회:학술대회논문집
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• 한국섬유공학회 2003년도 가을 학술발표회 논문집
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• pp.245-246
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• 2003

최근 정보통신 산업의 급속한 성장으로 평판 표시소자의 개발에 많은 관심이 모아지고 있다. 특히 이 중에서 액정 표시소자(LCD)의 수요는 급증하고 있으며 그에 관련된 부품 및 소재의 중요성 또한 강조되고 있다. LCD 부품 및 소재에서 가장 중요한 역할을 하는 편광필름은 일반적으로 PVA (polyvinyl alcohol) 또는 polyene 구조를 갖는 고분자 필름에 요오드를 염착시켜 사용되어 왔다. 본 연구에서는 PVA Film에 저온 플라즈마 처리를 함으로서 편광도와 투과도에 어떠한 영향을 미치는지에 대해 알아보고자 한다. (중략)

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2022년도 가을 학술논문 발표대회
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• pp.113-114
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• 2022

The aim of the research is to evaluate the segregation resistivity of the mixture conditions by changing the PVA and borax solutions for thixotropic property on concrete mixture. Since the water addition caused by producing solutions of PVA and borax induces segregation of the concrete mixture, the unit water was reduced by replacing the water amount for PVA and borax solution. By replacing the water from PVA and borax solutions, the segregation was prevented with prefixed concrete mix design and thixotropic properties were also occurred.

• 대한토목학회논문집
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• 제44권5호
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• pp.603-613
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• 2024

This study evaluated the mechanical properties of high-tension performance biochar concrete, focusing on the effects of varying biochar cement replacement ratios (0 %, 1 %, 2 %, 3 %, 4 %, and 5 %). Mechanical properties, including compressive strength, tensile strength, and flexural strength, were tested. The results showed a general decrease in compressive strength with increasing biochar replacement, with significant reductions at 1 % to 3 % levels. PVA fiber reinforcement improved long-term compressive strength, particularly at higher biochar levels. Tensile and flexural strength also showed initial reductions with low biochar levels but improved at higher replacement levels. PVA fibers consistently enhanced tensile and flexural strength. SEM images confirmed the integration of biochar and PVA fibers into the cement matrix, enhancing microstructural density and crack resistance.

• KSBB Journal
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• 제6권4호
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• pp.395-402
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• 1991

A new process was developed to degrade PVA(polyvinyl alcohol) in desize wastewater. Two symbiotic bacteria of Pseudomonas strain G5Y and PW were immobilized on the media by adsorption. A natural zeolite was chosen as the best media considering cell adhesion capacity, sedimentation rate, and material cost. PVA and COD removal efficiencies of this system for synthetic wastewater were 84% and 85% at the retention time of 6 hr, when the volumetric loading rate was PVA 8g/L·day and COD 8g/L·day, and cell density was 19,775 mg/L. In case of desire wastewater, they were 78% and 72% at the retention time of 6 hr, respectively, when the volumetric loading rate was PVA 8g/L·day and COD 13.2g/L·day, and cell density was 32,899mg/L. In case of desize wastewater, PVA and COD removal efficiencies were lower than synthetic wastewater, but cell density of the desize wastewater was lower than that of the synthetic wastewater, because there were insufficiency of necessary nutrition and variety of desize materials in the desize wastewater. A pilot test was successfully performed showing 88% and 82%, PVA and COD removal efficiencies at the retention time of 24 hr, when volumetric loading rate were 4.7 PVA g/L·day and COD 6.9g/L·day, and cell density was 12,,324 mg/L.

• 한국농공학회논문집
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• 제53권2호
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• pp.35-43
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• 2011

This study aimed to investigate the engineering characteristics of PVA fiber-cement-soil mixture used to prevent or reduce brittle failure of cement-soil mixtures due to the tensile strength increase from the addition of a synthetic fiber. The engineering characteristics of PVA fiber-cement-soil mixtures composed of PVA fiber, soil, and a small amount of cement was analysed on the basis of the compaction test, the unconfined compression test, the tensile strength test, the freezing and thawing test, and the wetting and drying test. The specimens were manufactured with soil, cement and PVA fiber. The cement contents was 2, 4, 6, 8, and 10%, and the fiber contents was 0.4, 0.6, 0.8, and 1.0% by the weight of total dry soil. To investigate the strength characteristics depending on age, each specimen was manufactured after curing at constant temperature and humidity room for 3, 7 and 28 days, after which the engineering characteristics of PVA fiber-cement-soil mixtures were investigated using the unconfined compression test, the tensile strength test, the freezing and thawing test, and the wetting and drying test. The basic data were presented for the application of PVA fiber-cement-soil mixtures as construction materials.

• KSBB Journal
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• 제10권3호
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• pp.241-248
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• 1995

염색가공 폐수 중 난분해성 물질이 PYA를 처리 하기 위하여, 한천-acrylamide를 이용한 bead를 제 조한 후 air-lift 반응기에서 연속실험을 행하였다. 합성폐수의 PYA놓도가 $3,100mg/\ell$. 체류시간 24hr일 때 유출수의 농도는 $4500mg/\ell$ 이며, 제거효율은 85% 이상을 나타내었다. 실제 호발폐수의 경우 PYA 및 COD농도가 $3,253mg/\ell$, $4,500mg/\ell$일 때, 체류시간 24hr에서 유출수의 농도는 $840mg/\ell, 480mg/\ell$이며, 제거효 율은 81.3%와 85.2%로 각각 나타났다. bead의 지름이 lmm일 때는 내부의 미생물 성장 이 양호하였으나 bead의 지름이 2mm일 때는 기질 과 산소전달저항에 의하여 반지름의 48% 이상은 미 생물의 성장이 저해를 받았다. 고정화 반응기에서 전체 기질 제거속도 중 bead 내 고정화 cell의 제거 분율은 평균 70%로 나타났다. 현탁 반응기에서 희석율 $0.083hr^{-1}$ 이상에서는 기질 이용속도가 감소하였으나 고정화 반응기에서는 희석율 $0.125hr^{-1}$까지 거의 선형척으로 증가하였다. PYA 제거속도식에서 포화상수 $K_s=6.60(g PVA/\ell)$와 최대 비기질 이용속도 k=0.175(g PVA/g cell.hr)를 얻었다.

• 한국포장학회지
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• 제7권1호
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• pp.1-8
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• 2001

This study was carried out to develop a new insolubilizer for water resistency enhancement and to evaluate its optimum apply method to corrugated paper. The addition of polyvinyl alcohol(PVA) backbone polymer to conventional starch glue caused a poor dispersibility, but flavonoid resin addition showed a good runnability and water resistency. The double coatings(top & under) of water-proof chemicals to corrugating liner made even better the water resistency of corrugating paper. This study suggested that water-proof chemical treatments be an effective method in water-resistant corrugating paper manufacturing for a cold chain system.

• 대한의용생체공학회:의공학회지
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• 제43권4호
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• pp.251-258
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• 2022

Silk fibroin microparticles were fabricated using a phase separation technique between silk fibroin solution and polyvinyl alcohol. We found that the concentration of polyvinyl alcohol determines the size of microparticles. The mean diameter of the silk fibroin microparticles varied from 3.48 ㎛ to 4.05 ㎛. The silk fibroin microparticle size increased as a function of the concentration of PVA in aqueous silk solution. The resulting silk fibroin microparticles have narrow size distribution (i.e. monodisperse) and smooth/spherical surface. Also, we studied the effects of mouse serum, sodium phosphate buffer (PBS), and pH on the stability of the silk fibroin microparticles. Overall, we demonstrated the simple method to fabricate and to control the silk fibroin microparticles that makes our silk microparticles to be usable for a potential drug delivery carrier.