• 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.

• Proceedings of the Membrane Society of Korea Conference
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• 1995.04a
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• pp.42-43
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• 1995

현재 에탄올 분리공정에서 사용하고 있는 투과증발분리 공정은 7-10%의 fermentation broths로 부터 나온 feed를 재래식 증류법으로 약 95%의 등비 혼합물까지 농축한 후 가교 polyvinylalcohol(PVA)를 사용하여 투과증발을 행하여 99.5%의 에탄올을 제조하고 있다. 현재 세계적으로 가장 많이 쓰이고 있느느 투과증발막으로는 독일의 GFT사로부터 개발되었고 PVA막을 PAN 부직포에 coating하여 제조하고 plate and frame type의 module을 써서 pervatporation unit를 생산하고 있다. 이러한 PVA 막보다 우수하며 여러 유기물 범위에서 사용가능한 막을 제조하기 위하여 많은 노력이 이루어지고 있다. 이같은 개량된 투과증발막을 제조하기 위하여 본 연구에서는 천연에 풍부히 존재하는 천연고분자인 키토산을 이용하였다.

• Proceedings of the KSAR Conference
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• 2002.06a
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• pp.33-33
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• 2002

소난자 체외성숙에 있어 소 태아혈청 (fetal bovine serum: FBS) 첨가시 높은 성숙율을 보이며 핵 이식 후 배 발달율에 있어서도 높다. 하지만 배양액 내에 포함된 소 태아혈청은 수정란 이식 후 태아의 발육 중 및 태어난 직후에 발생되는 송아지에서 나타나는 몇몇 비정상적인 현상들의 원인인 것으로 보고되고 있다 (Walker 등, 1998). 본 실험은 성숙배양시 소 태아혈청과 이의 대체물질로서 BSA 또는 PVA 와 같은 macromolecules의 첨가가 소 난자의 성숙과 핵 이식 후 배 발달에 미치는 효과를 알아보기 위하여 실시하였다. (중략)

• Journal of the Semiconductor & Display Technology
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• v.17 no.3
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• pp.41-45
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• 2018

Two-dimensional (2D) materials have been studied extensively due to their excellent physical, chemical, and electrical properties. Among them, we report the material and device characteristics of tin disulfide ($SnS_2$). To apply $SnS_2$ as a channel layer in a transistor, $SnS_2$ channels were formed by a stripping method and a transfer method. The limitation of this method is that it is difficult to produce uniform device characteristics over a large area. Therefore, we directly deposited $SnS_2$ by atomic layer deposition (ALD) and then performed lithography. This method was able to produce devices with repeatable characteristics over a large area. However, the $SnS_2$ film was damaged by the acetone used as a photoresist (PR) developer during the lithography process, with the electrical properties of mobility of $2.6{\times}10^{-4}cm^2/Vs$, S.S. of 58.1 V/decade, and on/off current ratio of $1.8{\times}10^2$. These results are not suitable for advanced electronic devices. In this study, we analyzed the effect of acetone on $SnS_2$ and studied the device process to prevent such damage. Using polyvinyl alcohol (PVA) as a passivation layer during the lithography process, the electrical characteristics of the $SnS_2$ transistor had $2.11{\times}10^{-3}cm^2/Vs$ of mobility, 11.3 V/decade of S.S, and $2.5{\times}10^3$ of the on/off current ratio, which were 10x improvements to the $SnS_2$ transistor fabricated by the conventional method.

• Journal of Embryo Transfer
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• v.15 no.2
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• pp.191-196
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• 2000

the present study was carried out to develop a completely defined culture system and determine if high NaCl concentrations in defined (PVA added) or semi-defined (BSA added) medium is toxic to bovine embryos. Oocytes from slaughterhouse ovaries were matured and fertilized in vitro. After 30 h of insemination, only 2-cell stage embryos were selected and cultured for this experiment. The culture media used were as follows : TLP(114 mM of NaCl) + BSA (3 mg/ml), TLP + PVA (1 mg/ml), mTLP(96 mM of NaCl) + BSA, mTLP + PVA. Six to ten embryos were placed into a 30$\mu$1 drop of each medium and the embryos were examined at 10 day post-insemination without medium renewal. The experiment was replicated 4 times. All data were analyzed by chi-square. There were no significant differences among TLP-BSA, mTLP-BSA and mTLP-PVA in blastocyst development (21.6, 17.2 and 20.2%), respectively. Also, no differences were obtained in hatching rates (11.7, 9.9 and 12.2%), respecitively. However, there were significant differences between TLP-PVA (1.7% and 0.6%) and other group in blastocyst formation and hatching rates, respectively (p<0.01). Development of in vitro produced embryos cultured in BSA containing medium was not affected by high NaCl concentration, but in the completely defined medium, embryonic development was highly affected by NaCl. This study shows that reduced NaCl concentration in completely defined medium is beneficial for development of bovine pre-implantation embryos in vitro.

• Journal of Radiation Industry
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• v.5 no.2
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• pp.119-124
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• 2011

Silver nano-particles (AgNPs) have attracted much attention for centuries due to their unique optical properties, electrical conductivities, oxidative catalysis, and antibacterial effect. In this study, AgNPs have been prepared by using aqueous $AgNO_3$ solution in the poly(vinyl alcohol) (PVA)/poly(ethylene glycol) (PEG) hydrogels. PVA and PEG powders were dissolved in deionized water, and then irradiated by a gamma-ray with a radiation dose of 50 kGy to make hydrogels. PVA/PEG hydrogels were dipped into $1.0{\times}10^{-2}M$ $AgNO_3$ solution for 1 hour. After that, the swollen hydrogels were irradiated by gamma-ray for the formation of AgNPs. FE-SEM is used to observe the formation of AgNPs as a function of the content of PEG and the irradiation dose. Also, AgNPs in the PVA/PEG hydrogels were monitored by UV-Vis. It is observed that the content of PEG and gamma-ray irradiation in the hydrogel is crucial to the formation of AgNPs. Finally, antibacterial tests indiacted that the hydrogel containing silver nanoparticle has antibacterial activity.

• Analytical Science and Technology
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• v.8 no.3
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• pp.335-340
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• 1995

Automatic biochemical oxygen demand(BOD) measurement system has heen developed using a microbial membrane electrode, prepared from Bacillus subtilis and polyvinyl alcohol(PVA). The automatic BOD measurement system showed a linear response curve up to BOD 60 ppm using a glucose/glutamic acid standard solution, and all the BOD measurement processes are carried out automatically to calculate BOD whithin 10 min after each sample injection. The response times of the microbial electrode was 5 minutes with a 5 min recovery time between measurements and the relative error of the BOD estimation was within 10%.

• Macromolecular Research
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• v.15 no.5
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• pp.412-417
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• 2007

In the present study, crosslinked poly(vinyl alcohol) (PVA) membranes were prepared at different temperatures using poly(styrene sulfonic acid-co-maleic acid) (PSSA_MA) (PVA:PSSA_MA = 1:9). The hybrid mem-branes were prepared by varying the TEOS content between 5 and 30 wt%. The PSSA_MA was used both as a crosslinking agent and the hydrophilic group donor ($-SO_3H$ and/or-COOH). The proton conductivity increased with up to 20 wt% TEOS, but decreased above this level, although the water content decreased with increasing TEOS content. This result suggests that the silica doped into the membrane improved the formation of proton-conduction pathways due to the absorption of molecular water. The PVA/PSSA_MA/Silica containing TEOS 20% showed both high proton conductivity (0.026 S/cm at $90^{\circ}C$) and low methanol permeability ($5.55{\times}10^{-7}cm^2/s$).

• Journal of Embryo Transfer
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• v.13 no.3
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• pp.235-243
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• 1998

In this study, we investigated the effects of three kinds of culture medium (Charles and Rosenkrans; CRlaa, Tyrode's; TALP, synthetic oviduct fluid: SOF), insulin transferrin + selenium complex (ITS), macromolecules(polyvinyl alcohol: PVA, fetalb-ovine serum: FBS) and NaCl on the development of early bovine embryos. In experiment 1, there were no differences in embryo development among three kinds of embryo culture medium (CR $l_{aa}$ , TALP, SOF). In experiment 2, BSA, FBS and PVA were added each in TALP as macromolecule sources. The developmental rates of embryos in BSA or FBS added TALP were significantly higher than in PVA added one (p〈0.01), but there was no difference between BSA and FBS added groups. In experiment 3, bovine embryos were cultured in TALP with the following supplements: BSA alone(1, 3 or 8 mg/ml, each) or BSA(1, 3 or 8 mg/ml, each)+ITS (10$\mu\textrm{g}$/m1 insulin, 5 $\mu\textrm{g}$/ml transferrin, 5 ng/ml selenium). In higher concentration of BSA and ITS supplemented groups, the developmental rates over compacted morula were higher than others, but there was a significant effect of ITS only in 1 mg/ml of BSA added group (p〈0.05). In experiment 4, the effect of reduced concentration of NaCl was evaluated. The developmental rate over compacted morula in the medium containing 90 mM of NaCl was higher than in 114 mM group (p〈0.05). In conclusion, BSA could be used as a macromolecule source in bovine embryo culture, and ITS, as a serum substitute, could be used for improving of embryonic development. Also, reduction of NaCl concentration from 114 mM to 90 mM may improve the development of bovine embryos.bryos.

• Journal of the Society of Cosmetic Scientists of Korea
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• v.49 no.1
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• pp.67-74
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• 2023

In this study, for a natural cosmetics market, we sought to explore alternatives that can replace polyvinyl alcohol (PVA) of peel-off packs. A peel-off type pack was prepared by combining pullulan, a water-soluble polysaccharide, and other polysaccharides (sodium hyaluronate, cellulose gum, hydroxyethyl cellulose, sodium alginate, corn starch), and the pH, viscosity, and stability against temperature of each peel-off type pack were confirmed. The thickness and tensile strength of the manufactured film were measured for comparison with the PVA peel-off type pack, and applicability, drying speed, and removal degree were measured. Among them, the pullulan-sodium hyaluronate peel-off type pack showed excellent film formation ability to replace the peel-off type pack containing PVA with 5.12% thin film thickness and 4.23% high film tensile strength. When applied to actual skin, the degree of spread of the pack, the usability that can be uniformly applied, and the formation and removal strength of the film when removed after drying were also similar to the peel-off type pack containing PVA. Therefore, it was confirmed that the film formed of pullulan-sodium hyaluronate showed enough physical properties to replace the PVA of the peel-off type pack as a natural peel-off type pack.