• 한국건축시공학회지
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• 제12권3호
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• pp.332-339
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• 2012

In this study, six mortar mixes were tested in order to examine the significance and limitations of hydrophilic fiber in terms of its capacity to enhance the tensile resistance of Hwangtoh mortar. Lyocell, polyamide and polyvinyl alcohol (PVA) fibers were selected for the main test parameters. The tensile capacity of mortars tested was evaluated based on the splitting tensile strength and the modulus of fracture, while their ductility was examined using the toughness indices specified in ASTM. Test results showed that the addition of lyocell and PVA fibers had little influence on the flow of the Hwangtoh mortars. To enhance the tensile capacity and toughness index of Hwangtoh mortar, it is proposed that fiber spacing above 0.0003 is required, regardless of the type of fiber.

• 한국환경보건학회지
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• 제16권1호
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• pp.21-28
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• 1990

As a research for treatment of waste water by biological method, we investigated general characteristics of waste water and isolated some useful bacteria which effectively treated waste water. Compositions of waste water were analyzed to give COD 2060 ppm, PVA 560 ppm, T-N 50 ppm, T-P 3.3 ppm and PH 12. Also, we inverstigated optimum nutrients requirement and growth conditions by mixed culture as well as the effect of coagulants. The COD removal rate reached maximum state for 48 hrs culture at pH 7.0 and 30$^{\circ}$C. Alum as the coagulated was the most effective. The COD removal rate was also increased by supplementing 10 ppm phosphorous sources as additional nutrients. The COD of waste water was reduced to 10% of its initial value by the continuous culture. As a result of overall experiments the COD of effluents became about 100 ppm and final pH 7.

• Fibers and Polymers
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• 제6권2호
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• pp.174-179
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• 2005

The present paper studies the effect of chitosan, cationic starch and polyvinyl alcohol (PVA) as sizing agents to enhance surface properties of kenaf paper. The polymers were incorporated into the sheets by spray application. The results clearly showed that the addition of chitosan to a sheet formed from beaten fibers had excellent improvement in surface properties, compared to the effect of other additives. Sizing quality of cationic starch fairly matched with the sizing quality of chitosan, however, it was able to reduce the water absorption potential of paper more than chitosan at a same concentration. In most other properties, particularly the most important property for printing papers, surface smoothness, chitosan-sized papers are superior to the paper sized with cationic starch or PVA.

• Bulletin of the Korean Chemical Society
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• 제13권3호
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• pp.240-245
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• 1992

The effect of the addition of sodium dodecyl sulfate (SDS) to a buffered mobile phase (pH 3.4) on the retention of nucleotides, nucleosides and bases was investigated with a polyvinyl alcohol (PVA) column. Depending on the concentration of SDS, two different trends in the retention of nucleosides and bases containing an $NH_2$ group were observed. If the concentration of SDS was less than 5.5 mM, the retention of compounds containing an $NH_2$ group increased as the concentration of SDS in the mobile phase increased. In contrast, if the concentration was greater than 5.5 mM, the retention of compounds containing an $NH_2$ group decreased. Thus, the SDS acted as an ion-pairing reagent at lower concentration but formed micelles at higher concentrations. The retention behavior of the nucleosides and bases in the presence of a micellar concentration of SDS in the mobile phase on the PVA column was compared to the retention behavior on other types of columns.

• 멤브레인
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• 제33권6호
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• pp.369-376
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• 2023

본 연구에서는 에너지 소모가 큰 기존 진공 증류 공정의 대안으로 친환경이면서 에너지 효율적인 투과증발 분리공정을 이용하여 1,2 hexane diol/water (1,2 HDO/water) 혼합물에서 물을 분리하는 데 적용되었다. 사용한 분리막은 glutaraldehyde (GA)로 가교된 PVA를 알루미나 중공사 막(Al-HF) 내부에 코팅하여 사용하였다. 1,2 HDO/water 투과증발 분리공정에서는 PVA/GA 비율, 경화 온도 및 투과증발 분리공정 운전 조건에 대한 막의 최적화를 연구하였다. 장기 안정성 시험에서 PVA/GA (몰 비율 = 0.08, 경화 온도 = 80℃) 로 코팅된 Al-HF 막이 공정온도 40℃에서 1.90~2.16 kg/m²h 범위의 투과도를 보였으며, 투과용액의 수분 함량은 99.5% (separation factor = 68) 이상이었다.

• 대한화학회지
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• 제19권4호
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• pp.280-285
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• 1975

Polyglyceryl phthalate, bisphenol A-epichlorohydrin 縮重合物 및 polyvinyl alcohol의 naphthoquinone-1,2-diazide-5-sulfonyl esters(PGND, BEND 및 PVAND)에 대해 未增感 및 增感한 경우의 IR 스펙트럼을 측정하여 그들의 光分解機構를 硏究하였다. o-quinonediazide에 기인하는 C=N= 및 C=0의 흡수가 露光에 의해 減少내지는 消失하고있었고 또한 indene carboxylic acid의 C=0 흡수강도가 증가되고 있는 것으로 보아 o-quinonediazide group 이 光에 依하여 分解하여 알카리 수용액에 가용성인 indene carboxylic acid로 분해되는 것으로 추정된다. 한편, 露光時間에 대한 增感 및 未增感試料의 吸收强度의 變化를 측정하므로서 增感劑의 增感效果도 아울러 검토하였다.

• Composites Research
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• 제25권5호
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• pp.159-163
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• 2012

냉매의 비등이나 응축같은 열전달 향상을 위하여 금속 표면위에 탄소나노튜브(CNT)를 코팅하는 것을 연구하였다. 분산제와 PVA(polyvinyl alcohol) 용액으로 분산 처리된 다중벽 탄소나노튜브/CuO의 복합 분말 코팅액을 구리기판위에 도포한 후 소결을 하였다. 본 논문에서는 CNT/CuO 소결 코팅시 다양한 분산제를 사용하여 소결 전후의 조직 형상 변화 및 특징을 실험적으로 평가하였다. 분산제로는 THF(Tetrahydrofuran), SDBS(Dodecylbenzenesulfonic acid sodium salt), SDS(Sodium dodecy sulfate)가 사용되었다. 각각의 시편들은 주사전자현미경, 열중량분석, 시차주사열량측정법, 라만분광법을 사용하여 분석하였다.

• Computers and Concrete
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• 제31권3호
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• pp.197-206
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• 2023

In this paper, the bending performance of a MSFRHPC (containing steel fiber, polyvinyl alcohol (PVA) fiber, and CW)-reinforced beam was studied for the first time. Introducing a multiscale fiber system increased the first crack load (up to 150%), yield load (up to 50%), and peak load (up to 15%) of reinforced beams. The multiscale fiber system delays cracking of the reinforced beam, reduces crack width of the reinforced beam in normal use, and improves the durability of the beam. Considering yield load and peak load, the reinforcing effect of multiscale fiber on the high-reinforcement ratio beam (1.00%) is better than that on the low-reinforcement ratio beam (0.57%). Introducing fibers slowed the development of cracks in the reinforced beam under bending. With the added hybrid fiber, the deformation concentration of reinforced beams after yield was more significant with concentration in 1 or 2 cracks. A model for predicting the flexural capacity of MSFRHPC-reinforced beams was proposed, considering the action of multiscale hybrid fibers. This research is helpful for structure application of MSFRHPC-containing CW.

• Journal of Pharmaceutical Investigation
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• 제28권4호
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• pp.275-282
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• 1998

In order to develop a desirable in vitro release which correlates well with in vivo bioavailability, hollow type suppository containing Propranolol HCl(PPH) powder in the cavity and conventional type suppository with dispersed PPH in the base were prepared. Polyvinyl alcohol (PVA) hydrogel as a base and PPH as a model drug were used for the preparation of suppository. The rates of drug release from the suppositories were studied by Paddle method, Muranish method, Dialysis tubing method and Rotating dialysis cell method. The release profiles from suppositories using the four different release tests were compared. After a rectal administration in rat, the mean $C_{max}$ of hollow type suppository was significantly lower than that of conventional type, but $T_{max}$, $AUC_{0{\to}12}$ and MRT of hollow type were significantly higher 1.6 times, 1.2 times and 1.9 times than those of conventional type, respectively. The computer program was used to simulate plasma concentration from in vitro released amounts of drug and in vivo pharmacokinetic parameters. Based on comparison of the simulated bioavailability from computer program with experimental bioavailability in rat we have found out in vitro release test which correlates well with in vivo bioavailability. Our results have shown the best correlation between in vitro release and in vivo bioavailability in PPH-PVA hydrogel hollow type suppository for the paddle method and conventional type suppository for the rotating dialysis cell method. In this work we propose that PPH-PVA hydrogel suppository shows in vitro-in vivo correlation. This data should help to optimize the formulation of the drug and provide a basis for quality control procedures.

• Membrane and Water Treatment
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• 제10권3호
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• pp.245-250
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• 2019

Prussian blue (PB) is well known for its excellent $Cs^+$ ions adsorption capacity. Due to the high dispersibility of PB in aqueous phase, composite materials imbedding PB in supporting materials have been introduced as a solution. However, building PB particles inside porous supporting materials is still difficult, as PB particles are not fully formed and elute out to water. In this study, we suggest layer-by-layer (LBL) assembly to provide better immobilization of PB on supporting materials of poly vinyl alcohol sponge (PVA) and cellulose filter (CF). Three different PB attachment methods, ex-situ/in-situ/LBL assembly, were evaluated using PB leaching test as well as $Cs^+$ adsorption test. Changes of surface functionality and morphology during PB composite preparation protocols were monitored through Fourier transform infrared spectroscopy and scanning electron microscopy. The results indicate that LBL assembly led to better PB attachment on supporting materials, bringing less eluting PB particles in aqueous phase compared to other synthesis methodologies, such as ex-situ and in-situ synthesis. By enhancing the stability of the adsorbent, adsorption capacity of PVA-PB with LBL improved nine times and that of CF-PB improved over 20 times. Therefore, the results suggest that LBL assembly offers a better orientation for growing PB particles on porous supporting materials.