• 전기학회논문지P
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• 제52권3호
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• pp.113-120
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• 2003

Plasma display panels normally utilize the binary coded light emission scheme for gray scale expression. Subsequently, this expression method makes dynamic false contours. We propose the "E3DSM(enhanced 3-dimension scattering method)" that improved existing 3-d scattering method and the "HAM(histogram analysis method)" that is decided the driving schemes and subfield selections with histograms of images. Simulation results show the improving image quality.

• 폴리머
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• 제39권3호
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• pp.370-381
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• 2015

고분자와 용매의 굴절률이 서로 일치되어 자체 산란광의 세기가 극소화된 시스템인 폴리(비닐 아세테이트) (PVAc)/디메틸설폭사이드(DMSO) 계에 폴리스티렌 라텍스 탐침입자(표시 직경 200 nm)를 소량 첨가한 뒤 동적 광산란법으로 용액의 PVAc 농도에 대한 입자의 확산 거동을 정밀하게 조사하였다. 구형 입자의 환산확산계수의 농도의존성은 환산농도 $C[{\eta}]$의 신장지수함수로 분석할 수 있었고, 묽은 농도에서는 배제층의 두께가 일정하게 유지되었으나 초기 준희박 농도인 $1{\leq}C[{\eta}]{\leq}2.5$ 범위에서는 배제층의 사슬농도 의존지수가 -0.8로써 이론적 계산치 -0.85와 일치하였다. 그러나 보다 높은 농도에서는 배제층의 두께가 이론적 예측보다 급속히 감소하는 현상 또한 관찰되었으며, 그 원인은 인접한 탐침 입자들 사이에 존재하는 Oosawa 인력 때문인 것으로 설명할 수 있었다.

• 폴리머
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• 제28권2호
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• pp.154-161
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• 2004

폴리(4-비닐피리딘)의 질소 원자에 메틸기를 부착시켜 4차아민화시켜서 부분적으로 개질된 폴리(4-비닐피리딘)을 얻었고, 부분 개질된 폴리(4-비닐피리딘)의 구조를 수용액상에서 레이저 광산란 및 형광법 등을 이용하여 조사한 결과, 자기 응집현상에 의하여 핵-껍질 구조를 가지고 있는 것으로 나타났다. 즉 사슬의 소수성 부분은 상호작용에 의하여 중심부에 모여있고, 4차화된 아민의 양전하를 가진 친수성 부분은 바깥 껍질을 형성하고 있었다. 이 고분자 수용액에 음이온 계면활성제인, 도데실 황산 소듐을 첨가하면 이들 사이에 임계 응집 농도가 존재하며, 이 임계 응집 농도는 특히 NaCl 농도 0.1 M 이상에서는 급격히 감소하는 경향을 보여주었다. 또한 계면활성제의 첨가에 따라 생성된 고분자-계면활성제의 복합 응집체의 입자크기 변화 등을 동적 광산란으로 측정 분석하였다.

• 폴리머
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• 제36권5호
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• pp.628-636
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• 2012

폴리(비닐 알코올)(PVA)/디메틸설폭사이드 용액에 폴리스티렌 라텍스 구형입자(직경 범위: 100~300 nm)를 소량 첨가한 뒤, 구형 입자 표면에 형성된 사슬 배제층 두께가 사슬의 농도에 따라 어떻게 의존하는지를 동적 광산란법으로 조사하였다. 묽은 용액 농도에서는 배제층의 두께가 PVA 사슬의 회전반경의 $63{\pm}3%$ 수준에서 일정하게 유지되었었으나 준희박 용액 농도의 초기 영역인 $1.5{\leq}C[{\eta}]{\leq}3$ 범위에서는 배제층 두께 ${\delta}$의 고분자 농도 의존성은 이론치 -0.75와 비슷한 ${\delta}{\sim}C^{-0.8}$로 얻어졌다. 보다 높은 농도 $C[{\eta}]$ >3 이상에서는 배제층의 두께가 급격히 감소하는 것으로 나타났는데 그 이유는 탐침입자간 Oosawa 인력에 의하여 유발된 응집효과가 그 원인인 것으로 설명할 수 있었다.

• Bulletin of the Korean Chemical Society
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• 제19권10호
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• pp.1054-1059
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• 1998

Fluorescence and dynamic light scattering measurements were applied to the study of formation and structure of aggregated colloidal particles in modified poly(ethylene-co-methylacrylate) ionomers in aqueous solution. Both 8-anillino-l-naphthalene-sulfonic acid (ANS) and pyrene were used as fluorescence probe to obtain the information on the structure of particle surface and inside, respectively. Three different ionomers used in this study started to aggregate at very dilute concentration, 3-8 x 10-6 g/mL. In this study, we demonstrate that the polyethylene ionomers can form stable nanoparticles. The hydrophobic core made of the polyethylene backbone chains is stabilized by the ionic groups on the particle surface. Such a formed stable nanoparticles have a relatively narrow size distribution with an average radius in the range of 27-48 nm, depending on the kind of ionic groups. Once the stable particles are formed, the particle size distributions were nearly constant. This study shows another way to prepare surfactant-free polyethylene nanoparticles.

• Journal of Pharmaceutical Investigation
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• 제22권2호
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• pp.115-124
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• 1992

The characteristics and stabilities of phosphatidylcholine liposomes covalently coupled with immunoglobulin fragments prepared by the REV method were investigated by the dynamic light scattering, absorbance and calcein release. Using a sulfhydryl-reactive phospholipid derivative of N-[4$({\rho}-maleimido-phenyl)$ butyl] phosphatidylethanolamine (MPB-PE), Fab' antibody fragments were covalently combined with preformed large unilamellar vesicles (LUV), Coupling ratio was $250\;{\mu}g$ of $Fab'/{\mu}mol$ of phospholipid in vesicles, From dynamic light scattering, it was found that the size of the vesicles increases as the ratio of cholesterol to lipid increases, but that apparently, the size of liposomes was not sensitive to the existence of Fab' fragments. Regardless of inserting Fab' fragments, the absorbance of liposomes decreased as the amounts of bile salt (BS) added. At very low BS concentrations, BS/lipid aggregates would be formed in the outer vesicles monolayer, while, at the high BS concentrations, mixed micelles would be preferred. The vesicles incorporated with Fab' fragments, however, are more resistant to the bile salts than the MPB-PE vesicle are. The absorbance of vacant liposomes and calcein release resulted in that the Fab' vesicles and MPB-PE vesicles by the REV method are very stable, but that those by the sonication method sufferred the significant change of turbidities.

• 대한화장품학회:학술대회논문집
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• 대한화장품학회 2003년도 IFSCC Conference Proceeding Book II
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• pp.319-329
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• 2003

Ursolic acid (UA) and oleanolic acid (OA) are pentacyclic triterpenoids which are widely distributed in plants, and their derivatives are aglycones of many naturally occurring saponins. It is known that pentacyclic acids may possibly enhance the mechanical barrier functions of cell membranes in plants. Recently, it has been reported that OA and UA have interesting biological activities on skin, such as anti-inflammatory and anti-wrinkle activities. Since triterpenoids are extremely insoluble and their solubility problem limits skin-care application, OA and UA were encapsulated in liposomes via micelle-to-vesicle transition to overcome poorly soluble property and enhance biological efficacy. Optimal molar ratio of OA to lecithin was found to exist for producing liposomes of small hydrodynamic size and liposomal suspensions without recrystallized precipitation of OA. From electron micrograph and dynamic light scattering studies, reconstituted OA-containing liposomes without severe mechanical treatment showed small hydrodynamic size about 150 nm. Wide-angle X-ray diffraction coupled with dynamic light scattering revealed that optimal amount of OA in liposome was 25.4 mole %. In biological evaluation, OA-containing liposome significantly increased filaggrin and transglutaminase as markers of keratinocyte differentiation in epidermal layer of hairless mouse, whereas ursolic acid-containing liposome did not show noticeable increase of filaggrin and transglutaminase compared to empty liposome. It is concluded that nano-scaled liposomes containing triterpenoids were spontaneously prepared by vesicular transition from mixed micelle and liposomal triterpenoids can enhance skin absorption of triterpenoid and biological efficacy.

• 대한화장품학회지
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• 제34권1호
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• pp.9-14
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• 2008

오일/수첨 레시틴/물 계에서 전단력이 다른 두 혼합기로 제조된 나노에멀젼의 안정성에 대하여 연구하였으며, 계면활성제의 농도에 따른 나노에멀젼의 입자 크기와 안정성을 조사하였다. 입자의 크기는 광산란법에 의하여 측정하였으며 입자크기의 시간에 따른 변화를 관찰하였다. 실험 결과 나노 에멀젼 불안정화 과정은 Ostwald ripening에 의해 지배되었다. 입자 크기가 100~200nm 범위에서는 오일에 대한 계면활성제의 비율이 증가함에 따라 안정성이 감소하였으나 입자 크기가 300~400nm의 범위에서는 반대의 경향을 보였다.

• 약학회지
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• 제39권5호
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• pp.495-505
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• 1995

The O/W microemulsion systems were made from 2 or 4% (w/w) oil (soybean oil, olive oil or isopropyl myristate) and 10, 15 or 20% (w/w) Brij 96. They were compared with micellar solution of equivalent surfactant concentration m therms of physicochemical properties, and the solubilization of sudan IV. They were characterized by dynamic light scattering, stability, surface tension, viscosity and rheogram. The mean diameters of O/W microemulsion systems were 10-15nm, and those of Brij 96 micellar solutions were 18-19 nm. Both of them were monodisperse systems. The O/W microemulsion systems showed Newtonian flow and their apparent viscosities were lower than those of micellar solutions. The surface tensions of O/W microemulsion systems were increased or decreased depending on the types of oil used, when compared with those of micellar solutions. The O/W microemulsion systems were very stable, and did not show any flocculation or aggregation. Their mean diameters were not changed after three months. But oxidation was observed in microemulsions without nitrogen gas at high temperature. There was a significant improvement in the sudan IV solubffimtion in micromulsion compared with that m the micellar solution containing equivalent concentration of surfactant. The size distribution and mean diameters of O/W micromulsions were not changed when sudan IV was solubilized.

• Bulletin of the Korean Chemical Society
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• 제21권6호
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• pp.623-627
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• 2000

Aggregation of hydrophobically end-capped poly(ethylene oxide)s: HEURs, denoted as $C_8$$EO_{380}$$C_8$, $C_12$$CO_{600}$$C_{12}$, and $C_{18}$$EO_{860}$$C_{18}$,are described using static fluorescence, dynamic light scattering, and atomic force microscope (AFM) techniques. The CAC (critical aggregation concentration) was determined by com-paring two fluorescent peaks which were influenced by the polarity of the probe dye molecules, pyrene. The aggregation occurs in concentrations higher than 10 g/L of $C_8$$EO_{380}$$C_8$ and the CAC decreases by increasing the side chain length. The dynamic light scattering experiment shows fast mode and slow mode decays, and both are diffusive. The fast mode does not depend on the concentration, but the slow mode shows concentration dependence influenced by the formation of an aggregated structure. The hydrophobic end groups effect more dominantly than the main chains for the formation of HEUR micelles. By increasing the concentration, the HEUR micelles change their structure from spheres to rodlike micelles, and finally make fused structures, which were visualized with atomic force microscopy.