• Korea-Australia Rheology Journal
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• 제17권2호
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• pp.79-85
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• 2005

Aqueous mixtures of hyaluronic acid and poly(vinyl alcohol) system and hydrogels thereof were introduced to obtain new bioartificial materials that have excellent mechanical properties, biocompatibility and enhanced rheological properties. The interactions between hyaluronic acid and poly(vinyl alcohol) and/or borax were investigated by rheological measurements. Preparation parameters of the aqueous mixtures were mixture composition, the degree of hydrolysis of poly(vinyl alcohol) and borax concentration. From the rheological behavior, it could be deduced that the key factor of the interaction between hyaluronic acid and poly(vinyl alcohol) was the hydrogen bonding between them and the effect was pronounced with borax. Enhanced viscosity was observed at the composition of $20wt\%$ of hyaluronic acid solution and $80wt\%$ of poly(vinyl alcohol) and borax solution. Rheological properties were influenced by the degree of hydrolysis of poly(vinyl alcohol) and borax concentration. As the degree of hydrolysis and borax concentration increased, rheological properties increased due to the increased hydrogen bonding and networking of hyaluronate aggregates. Physical hydrogels from hyaluronic acid and poly(vinyl alcohol) were prepared and the composition dependence of the gels was rheologically investigated as well.

• Macromolecular Research
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• 제15권7호
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• pp.623-632
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• 2007

Thermosensitive nanoparticles were prepared via the self-assembly of two different $poly({\varepsilon}-caprolactone)$-based block copolymers of poly(N-isopropylacrylamide)-b-$poly({\varepsilon}-caprolactone)$ (PNPCL) and poly(ethylene glycol)-b-$poly({\varepsilon}-caprolactone)$ (PEGCL). The self-aggregation and thermosensitive behaviors of the mixed nanoparticles were investigated using $^1H-NMR$, turbidimetry, differential scanning microcalorimetry (micro-DSC), dynamic light scattering (DLS), and fluorescence spectroscopy. The copolymer mixtures (mixed nanoparticles, M1-M5, with different PNPCL content) formed nano-sized self-aggregates in an aqueous environment via the intra- and/or intermolecular association of hydrophobic PCL chains. The microscopic investigation of the mixed nanoparticles showed that the critical aggregation concentration (cac), the partition equilibrium constants $(K_v)$ of pyrene, and the aggregation number of PCL chains per one hydrophobic microdomain varied in accordance with the compositions of the mixed nanoparticles. Furthermore, the PNPCL harboring mixed nanoparticles evidenced phase transition behavior, originated by coil to the globule transition of PNiPAAm block upon heating, thereby resulting in the turbidity change, endothermic heat exchange, and particle size reduction upon heating. The drug release tests showed that the formation of the thermosensitive hydrogel layer enhanced the sustained drug release patterns by functioning as an additional diffusion barrier.

• 대한치과보철학회지
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• 제38권4호
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• pp.484-491
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• 2000

Soft denture liners or conditioners may be valuable therapeutic materials. The life of these liners is short and varies, but it can be extended by the use of a mono-poly(polymethyl methacrylate coating material). This study determined whether coating three temporary soft denture liners with mono-poly affected the resiliency of soft liners, and evaluated the ability of mono-poly to prevent water absorption and alcohol loss from the underlying soft liners. $20{\times}12mm$ cylindrical specimens of Coe-Soft, Soft-Liner, Coe-Comfort soft lining materials were made and divided into two groups of mono-poly uncoated(control) and mono-poly coated specimens. Specimens were immersed in water and compressed on an instron universal testing machine and weighed at initial, 24 hours, 1 week, 2 weeks, and 4 weeks. Resiliency was determined by measuring the energy absorbed by the soft liners when stressed to a specific yield point. Mono-poly coating significantly increased the resiliency of the Soft-Liner, but had no effect on the other soft liners. Among the 3 soft liners, Soft-Liner showed the hightest resiliency and modulus of elasticity. The weight loss in Soft-Liner was the least among the 3 liners, and the weight loss in Coe-Soft was decreased by monopoly coating.

• Restorative Dentistry and Endodontics
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• 제25권4호
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• pp.561-574
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• 2000

Poly-P has been used to prevent decomposition of foods and has been shown to have inhibitory effect on the growth of gram positive bacteria. The purpose of this study was to evaluate the effect of poly-P on the growth of Porphyromonas endodontalis, a gram negative obligate anaerobic rod, endodontopathic bacterium. P. endodontalis ATCC 35406 was in BHI broth containing hemin and vitamin K with or without poly-P. Inhibitory effect of each poly-P which was added at the beginning(lag phase) or during(exponential phase) the culture, MIC(minimum inhibitory concentration) was determined by measuring the optical density of the bacterial cell at 540nm. Viable cell counts were measured to determined whether poly-P has a bactericidal effect. Leakage of intracellular nucleotides from P. endodontalis was determined at 260nm and morphological change of P. endodontalis was observed under the TEM(transmission electron microscope). Binding of 32P-labeled poly-P to P. endodontalis was examined. SDS-polyacrylamide gel electrophoresis and zymography were performed to observe the changes in protein and enzyme profiles of P. endodontalis, respectively. The results from this study were as follows : 1. The minimal inhibitory concentration(MIC) of poly-P to P. endodontalis appeared to be 0.04~0.05%. 2. Poly-P added to the P. endodontalis culture during the exponential phase of P. endodontalis was as much effective as poly-P added at the begining of the culture, suggesting that the antibacterial effect of poly-P is not much dependent on the initial inoculum size of P. endodontalis. 3. Poly-P are bactericidal to P. endodontalis, demonstrating the decrease of the viable cell counts. 4. Intracellular nucleotide release from the P. endodontalis, was not increased in the presence of poly-P and was not reversed by the addition of divalent cations like $Ca^{2+}$ and $Mg^{2-}$. 5. Under the TEM, it was observed that fine electro-dense materials were prominent in the poly-P grown P. endodontalis, appearing locally in the cell, and the materials were more abundant and more dispersed in the cell as the incubation time with poly-P increased. In addition, highly electron dense granules accumulated in many poly-P grown cells, most of which were atypical in their shape. 6. Binding of 32P-labeled poly-P to P. endodontalis appeared to be 32.8 and 45.5 and 53.4% at 30 minutes, 1 hours and 2 hours, respectively. 7. In the presence of poly-P. the synthesis of proteins with apparent molecular masses of 25, 27, 35, 45 was lost or drastically decreased whereas expression of a protein with an apparent molecular mass of 75 was elevated. 8. Proteolytic activity of P. endodontalis was decreased by poly-P. The overall results suggest that use of poly-P may affect the growth of P. endodontalis, and the anti-bacterial activity of poly-P seems largely bactericidal. Changes in shape, protein expression, and proteolytic activity of P. endodontalis by poly-P may be directly and indirectly attributed to the antibacterial effect of poly-P. Further studies will be needed to confirm the effect of poly-P.

• 폴리머
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• 제35권5호
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• pp.438-443
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• 2011

소수성 막의 파울링 현상 개선, 젖음성 향상을 통한 투과도 증가 등을 위하여 poly(vinyl amine), poly(styrene sulfonic acid), poly(vinyl sulfonic acid), 그리고 poly(acrylamide-co-acrylic acid) 등의 다양한 흡착소재를 polyethylene(PE) 다공성막 표면에 흡착용액 농도, 흡착시간, 염의 종류, 이온세기 등을 변화시키면서 순수 투과도를 측정하였다. 일반적으로 흡착용액의 농도, 흡착시간, 그리고 이온세기가 증가하면 투과도는 초기에 증가하다가 감소하는 경향을 보였다. Poly(vinyl sulfonic acid) 1000 ppm, $Mg(NO_3)_2$의 이온세기 0.1, 그리고 흡착시간 150초 조건에서 순수투과도가 35% 향상된 375 $L/m^2h$(LMH)를 얻었으며, poly(styrene sulfonic acid) 1000 ppm, NaCl의 이온세기 0.1과 0.2, 그리고 흡착시간 60초에서 각각 50%(411 LMH), 35%(374 LMH)의 순수 투과도 증가율을 보였다.

• 공업화학
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• 제26권4호
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• pp.458-462
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• 2015

전도성 고분자인 poly(3,4-ethylenedioxythiophene)-poly(styrene sulfonate) (PEDOT/PSS)의 투명한 필름을 제조하기 위해서는 바인더의 사용이 반드시 필요하다. 본 연구에서는 poly(vinyl alcohol) (PVA), poly(vinyl pyrrolidone) (PVP) 및 PSS를 바인더로서 검토하여 그 특성을 비교하였다. PEDOT/PSS 필름의 형성 여부는 기본적으로 바인더를 포함하는 코팅액의 표면장력 값에 의존하였다. PSS 또는 PVP를 바인더로 사용하였을 때는 필름이 형성되지 않거나 필름이 기재로 부터 쉽게 박리되는 현상이 나타났다. 그러나 PVA를 단독으로 사용하거나 또는 PSS 및 PVP를 PVA와 혼합하여 사용하면 투명하며 균일한 표면저항 값을 나타내는 대전방지 필름을 얻을 수 있었다. 필름의 접착력 및 장기 보관 안정성 등을 종합적으로 판단하면, PEDOT/PSS의 대전방지용 필름을 제조하기 위한 바인더로서는 PVA와 PSS의 혼합물이 최적인 것으로 나타났다.

• 한국진공학회지
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• 제12권2호
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• pp.130-135
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• 2003

최근, poly-Si 박막은 저가의 박막소자응용을 위하여 사용되어 왔다. 그러나, 유리기판 위에서 일반적인 고상결정화(SPC) 방식으로 poly-Si 박막을 얻기는 불가능하다. 이러한 단점 때문에 유리와 같은 저가기판 위에 poly-Si을 결정화하는 연구가 최근 다양하게 진행되고 있다. 본 논문에서는 급속열처리(RTA)를 이용하여 유연한 기판인 몰리브덴 기판 위에서 a-Si:H를 성장시킨 후 고온결정화에 대한 연구를 진행하였다 고온결정화된 poly-Si 박막은 150$\mu\textrm{m}$ 두께의 몰리브덴 기판 위에 성장되었으며 결정화 온도는 고 진공하에서 $750^{\circ}C$~$1050^{\circ}C$ 사이에서 결정화된 시료에 대하여 결정화도, 결정화 면방향, 표면구조 및 전기적 특성이 조사되었다. 결정화온도 $1050^{\circ}C$에서 3분간 결정화된 시료의 결정화도는 92%를 나타내고 있었다. 결정화된 poly-Si 박막으로 제작된 TFT 소자로부터 전계효과 이동도 67 $\textrm{cm}^2$/Vs을 얻을 수 있었다.

• 접착 및 계면
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• 제24권2호
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• pp.69-75
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• 2023

최근 자기복원(self-recovery) 코팅층을 가진 자동차용 도장면 보호필름의 적용이 증대되고 있다. 본 연구에서는 poly(urea-urethane) hybrid 자기복원 코팅층을 가진 poly(vinyl chloride) 기재 보호필름에 대한 기본 물성에 대한 평가 결과를 보고한다. Poly(urea-urethane) 기반 코팅층을 구성하고 있는 주요 화합물의 비율과 코팅층의 두께 변화에 따른 자기복원성능을 확인하였으며, 색차 값 측정을 통해 내오염성능을 정량화 하였다. 또한, 소수성 첨가제로 외부 오염에 대한 표면특성을 향상시키기 위하여, 소량의 실리콘계 반응형 첨가제를 코팅 조성물에 함량에 따른 easy-cleaning 효과와 접촉각을 확인하였다. 마지막으로, poly(urea-urethane) 자기복원 코팅층을 가진 보호필름의 장기간 사용에 따른 변색 및 변형에 대한 가능성을 확인하고자 촉진 내후성 평가를 진행하였다.

• 대한전기학회논문지
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• 제40권1호
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• pp.91-98
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• 1991

Electrical conductivity of poly (3-alkylthiophene) derivatives with substituted long alkyl chain such as poly (3-butylthiophene), poly (3-hexylthiophene), poly (3-octylthiophene), poly (3-decylthiophene), poly (3-dodecylthiophene), and poly (3-docosylthiophene) increases with increasing temperature. However, after attaining a maxiumum value, it decreases with further temperature increase. Hysteresis is also observed in the temperature dependence of conductivity and absorption spectra. The absorption spectra also changes rapidly at the phase transition. These phenomena are discussed in terms of the increase of the energy band gap in the liquid states due to the decrease of co-planarity of thiophene rings accompanied by remarkable conformation changes.

• Journal of applied mathematics & informatics
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• 제38권1_2호
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• pp.133-144
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• 2020

In this paper, we discuss generalized q-poly-Euler numbers and polynomials. To do so, we define generalized q-poly-Euler polynomials with variable a and investigate its identities. We also represent generalized q-poly-Euler polynomials E^(k)_n,q(x; a) using Stirling numbers of the second kind. So we explore the relation between generalized q-poly-Euler polynomials and Stirling numbers of the second kind through it. At the end, we provide symmetric properties related to generalized q-poly-Euler polynomials using alternating power sum.