• 생태와환경
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• 제44권4호
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• pp.358-363
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• 2011

본 연구는 영산강수계 광주지역에 대하여 XAD와 FTIR를 이용하여 자연유기물질에 대한 분포특성을 연구하였다. XAD 8/4 resin을 이용한 NOM fractionation 분석은 친수성 및 소수성을 변별하는데 사용되어졌다. FT-IR은 자연유기물의 구조에서 기능족을 분석하는데 사용되어졌다. XAD 조사에서 영산강본류의 광주상류지점(GJ-1), 광주하류지점(GJ-2), 광주천(GJC), 광주하수처리장(GJS) 등 4개 지점에서 대부분 친수성으로 조사되었다. 다만, 3월에 GJ-1 지점에서는 소수성이 주를 이루었다. 5월에는 수온의 상승과 함께 미생물의 활성의 증가로 4개 지점 공통적으로 친수성으로 조사되었고, 10월에는 3월과 매우 유사한 결과가 되었다. FT-IR 조사에서는 넓거나 높아 뚜렷한 피크들이 주로 지방족 화합물, 특히 OH 그룹, CH, $C-H_2$, $C-H_3$ 및 C-O 알코올 그룹들로 나타났고, 이들은 친수성 물질들이다. FT-IR 조사에서 그 외의 피크들은 약간의 방향족 화합물, 특히 C=O (Ketone) 그룹이 나타났다. 결과적으로 본 연구에서 영산강수계 광주지역은 주로 친수성 물질들이며, 지방족 화합물(OH, C-H etc.)인 것으로 조사되었다.

• Corrosion Science and Technology
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• 제8권3호
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• pp.103-109
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• 2009

An epoxy coating was designed to give a hydrophobic property on its surface by modifying it with three types of Amino Terminated Polydimethylsiloxane (ATP), and then effects of the modification on the structure, surface hydrophobic tendency, water transport behavior and hence corrosion protectiveness of the modified epoxy coating were examined using FT-IR spectroscopy, hydrothermal cyclic test, and impedance test. The surface of epoxy coating was changed from hydrophilic to hydrophobic property due primarily to a phase separation tendency between epoxy and modifier by the modification. The phase separation tendency is more appreciable when modified by ATP with higher molecular weight ATP at higher content. Water transport behavior of the modified epoxy coating decreased more in that with higher hydrophobic surface property. The resistance to localized corrosion of the modified epoxy coated carbon steel was well agreed with its water transport behavior and hydrophobic tendency.

• Environmental Engineering Research
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• 제11권4호
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• pp.181-193
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• 2006

The hydrophilic or hydrophobic characteristics of dissolved organic matter (DOM) from different origins in lake and river waters were investigated using spectrometric and chromatographic analyses of water samples. DOM in a deep, mesotrophic lake (Lake Unmun) was fractionated using three types of ion exchange resins and classified into aquatic humic substances (AHS), hydrophobic neutrals (HoN), hydrophilic acids (HiA), hydrophilic neutrals (HiN), and bases (BaS). The DOM fractionation provided insight into the understanding of the nature of heterogeneous DOM molecules present in different water sources. The UV/DOC ratios were determined for samples from the influent river and lake waters during DOM fractionation and incubation. AHS prevailed over DOM in the lake and river waters. After biodegradation, the relative contribution of AHS in the total DOM became more significant. It indicates that the AHS fraction would increase while water stay long time in the lake.

• Macromolecular Research
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• 제16권4호
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• pp.367-372
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• 2008

We fabricated tetra(5-n-nonyl-8-tert-butyl-2,3-pyrazino[2,3-b]indolo)porphyrazinato copper(II) (Cu-Pc-$C_8$) Langmuir-Blodgett (LB) films. We further investigated the influence of arachidic acid (AA) as a transfer promoter, as well as the effect of dipping speed, on the deposition of the films on hydrophilic and hydrophobic substrates. In the case of pure Cu-Pc-$C_8$ LB deposition on a hydrophilic substrate, the transfer ratio was close to one for up-stroke depositions, but the previously deposited film was peeled off and re-spread onto water at down-stroke depositions. Whereas the stability of the Cu-Pc-$C_8$ LB films was not improved by AA addition on hydrophilic substrates, the deposition of Cu-Pc-$C_8$ was significantly improved by the presence of AA on a hydrophobic substrate. The AA-assisted deposition had transfer ratio of close to 1 and was essentially stable up to 10-layer depositions. Comparison of the UV-visible spectrum of a Cu-Pc-$C_8$/AA LB film with that of Cu-Pc-$C_8$/AA solution in dichloroethane revealed that the Soret and Q bands for the Cu-Pc-$C_8$/AA LB film were broadened and red-shifted due to the aggregation of phthalocyanines upon assembly in the LB film.

• 한국정밀공학회지
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• 제29권8호
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• pp.913-919
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• 2012

This paper presents results for dispensing and measuring micro-particles using a pneumatic dispensing system. Particle-suspended liquid droplets were dispensed and analyzed quantitatively at various particle concentrations and applied pressures. By using a developed experimental setup, the number of particles and the particle volume ratio in sequentially dispensed droplets were measured. Hydrophilic and hydrophobic surfaces were tested to find a suitable surface for counting the number of particle. It was confirmed that the dispensed particles concentrated into the center of the droplet on the smooth CD surface after evaporation of liquid. As the applied positive pressure increased, the number of particles per droplet increased consistently and the volume fraction of particles remained constant.

• 전기화학회지
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• 제3권2호
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• pp.81-84
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• 2000

This article deals with various photochemical processes occurring at $TiO_2$ surface and its applications in practical living conditions. In the first part, we present an overview of $TiO_2$ photocatalysis under weak W illumination with a special emphasis on bactericidal and detoxification properties of $TiO_2$ films. The second part deals with the photoinduced super hydrophilic TiCt surftce which has a wide commercial applications. In the last part, we present our recent work on boehmite-based super hydrophobic surfaces containing small amount of $TiO_2$ to obtain self-cleaning effect.

• Journal of Pharmaceutical Investigation
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• 제19권4호
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• pp.173-178
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• 1989

Drug release rates from copolymer hydrogels were controlled by their hydrophilic-hydrophobic balances. As a model copolymer hydrogel, poly(acrylamide-co-styrene) was synthesized at different monomer composition. Release mechanisms of propranolol-HCI from the copolymer matrices were investisated. Swelling rates of the copolymer hydrogels retarded as their hydrophobicity increased. Swelling kinetics of the copolymer hydrogels regulated drug release rates via polymer relaxation controlled release mechanisms. Zero order drug release could thus be achieved within certain periods.

• 감성과학
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• 제5권3호
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• pp.67-74
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• 2002

Testing device was newly designed and built to measure the dynamic contact angle. The measurement was made using microscope interfaced with computerized image analysis system while the dynamic condition being controled using Instron. As specimens for the experiment, two different types of fibers, i.e., hydrophilic and hydrophobic, were prepared. In case of hydrophilic fiber, the increase of twist level gave the increase of contact angle. However, in hydrophobic yarn the increase of twist level gave the decrease of contact angle. When saline was used as a telling liquid, the increase of the concentration gave the increase of contact angle. The results rationalized clearly on the basis of known concepts could be used in designing fabric structure for the improvement of comport performance.

• 대한의용생체공학회:학술대회논문집
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• 대한의용생체공학회 1990년도 추계학술대회
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• pp.61-63
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• 1990

To develop better blood compatibility of commercial polyurethane(PU), PU surface was chemically modified wi th a hydrophobic perfluorocarhon or a hydrophilic polyethylene oxide(PEO) and/or sulfonated groups, respectively. The water contact angle of modified PUs varied from $110^{\circ}$ to $0^{\circ}$. All the modified PUs were more blood compatible than untreated PU. In particular, PEO-sulfonate grafted PUs showed a very enhanced antithrombogenicity due to the synergistic effect of PEO and $SO_3$ groups. Therefore more hydrophobic and hydrophilic PU surfaces are promising for improving the blood compatibility.

• 한국가시화정보학회:학술대회논문집
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• 한국가시화정보학회 2007년도 추계학술대회
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• pp.84-87
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• 2007

Recently, many studies concern on the slip flow and slip length, which allow liquid flow to reduce drag force in microchannel. However, until now not enough investigation is performed experimentally to understand the slip flow in the superhydrophobic microchannel exhibiting riblet structures on vertical wall. Here we investigated and compared the slip flows according to the surface characteristics; hydrophilic, hydrophobic, and superhydrophobic wettabilities. Using the micro-PIV, velocity profiles can be obtained in the glass (hydrophilic), PDMS (hydrophobic), and micro-structured PDMS (superhydrophobic) microchannels. For both PDMS and superhydrophobic PDMS microchannels, we observed the slip effects showing the microscale slip lengths. Due to the micro-riblet, there are two distinctive flow characteristics on the riblet surface and the liquid meniscus in the valleys.