• 한국전기전자재료학회논문지
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• 제11권3호
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• pp.174-180
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• 1998

In this work, the properties of FRP, which is applied recently in the composite insulating materials, by thermal treatment were investigated. The specimens were epoxy glass laminates fabricated by thermal press method and had the volume content of 46[%] cutted $45^{\circ}C$ in the fiber direction and 1.0[mm] thickness. The experimental results showed that the amount of weight loss, wettability, surface potential, and surface resistivity increased up to 200[$^{\circ}C$] as a function of temperature. Usually, most degradations caused the hydrophilic to decrease the contact angle. But, in this work on thermal-degradated FRP, we can confirm the introduction of hydrophobic properties by cross-linking and the ablation of polar small-molecules rather than chain scission and oxidation. Finally, weight loss and contact angle increased. These phenomena show the existence of hydrophobic surface. With the change to the hydrophobic surface and the electrical potential and resistivity on FRP surface increased. But, the dielectric properties and tensile stength are decreased.

• 공업화학
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• 제9권2호
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• pp.177-184
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• 1998

분체 형태의 소수성 고분자 polymethylmethacrylate(PMMA), poly vinyl chloride(PVC)와 친수성 금속 aluminium에 대한 water, glycerol, formamide, diiodomethane, 1,1,2,2-tetrabromoethane, 1-bromonaphthalene, acetone, chloroform, benzene, ethanol과 methanol과의 접촉각을 Washburn식을 기본으로 한 wicking법으로 측정하였다. 또한, 농도에 따른 음이온 계면활성제 SDS(sodium dodecyl sulfate)와 양이온 계면활성제 CTAB(cetyl trimethylamonium bromide) 수용액과의 접촉각을 측정하였다. 유기액체들과의 측정된 접촉각으로부터 Zisman plot을 사용하여 임계표면장력, ${\gamma}_c$를 예측하였으며, 농도에 따른 계면활성제 SDS와 CTAB수용액과의 접촉각으로부터 adhesion tension plot을 사용하여 ${\gamma}_c$를 예측하였다. 유기액체, 계면활성제 SDS와 CTAB수용액에 대해서 분체 PMMA의 ${\gamma}_c$는 각각 43.5, 28.3과 $36.2mNm^{-1}$이며, 분체 PVC의 ${\gamma}_c$는 각각 44.2, 28.0과 $34.8mNm^{-1}$값을 얻었다. 이로부터, 고체 표면의 적심성과 성질이 계면활성제의 첨가에 의해 변화됨을 알 수 있었다. 또한, 측정된 접촉각으로부터 조화평균식을 사용하여 각 고체의 표면자유에너지. ${\gamma}_s$와 그 성분 값들을 결정하였다.

• Korean Chemical Engineering Research
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• 제45권6호
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• pp.669-676
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• 2007

낙동강 매리지역 원수에 대해 유기물 성상분석을 한 결과, 소수성 물질이 43%, 친수성 물질이 39%, 반친수성 물질이 18%를 차지하고 있는 것으로 나타났으며, 각각의 유기물질에 대한 분자량 크기 분포 특성을 살펴보면 소수성 > 반친수성 > 친수성 물질의 순으로 분자량 분포특성을 보였다. 막 공극 크기에 따른 영향을 살펴본 결과 막 공극 크기가 증가할수록 공극 내에서 공극 막힘현상과 공극 흡착현상이 막오염의 주된 메카니즘으로 작용하여 투과 flux 감소율이 크게 나타나는 것으로 조사되었다. 막의 재질에 따른 영향을 살펴본 결과 소수성 막의 경우 친수성 막에 비하여 소수성 상호반응(hydrophobic interaction)에 의하여 유기물에 의한 막 오염 현상이 발생하여 투과 flux 감소율이 더 크게 나타나고 초기 투과 flux 감소율도 빠르게 진행되었다. 원수에 대한 막의 재질과 막의 공극크기에 따른 막오염 메카니즘 분석결과 소수성 재질의 막에서 막표면 오염을 나타내는 Kc, 막의 공극흡착현상을 나타내는 Ks, 막의 공극 막힘현상을 나타내는 Ki 값이 상대적으로 크게 나타났다. 막의 공극 크기에 따른 막 오염 메카니즘 분석결과 막의 100 kDa 이상의 공극이 큰막의 경우에는 소수성 계열의 유기물이 막의 공극 내부에서 막 오염을 유발하였으며, 10 kDa 정도로 공극이 작은 막의 경우 소수성과 친수성 계열 유기물이 막 표면에서 막 오염을 유발하는 메카니즘이 주원인으로 작용하였다

• 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.

• 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.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2013년도 제44회 동계 정기학술대회 초록집
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• pp.97-97
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• 2013

The exterior structures of natural organisms have continuously evolved by controlling wettability, such as the Namib Desert beetle, whose back has hydrophilic/hydrophobic contrast for water harvesting by mist condensation in dry desert environments, and some plant leaves that have hierarchical micro/nanostructures to collect or repel liquid water. In this work, we have provided a method for wettability contrast on metals by both nano-flake or needle patterns and tuning of the surface energy. Metals including steel alloys and aluminum were provided with hierarchical micro/nanostructures of metaloxides induced by fluorination and a subsequent catalytic reaction of fluorine ions on metal surfaces in water with various ranges from room to boiling temperature of water. Then, a hydrophobic material was deposited on the structured surfaces, rendering superhydrophobicity. Plasma oxidization induces the formation of superhydrophilic surfaces on selective regions surrounded by superhydrophobic surfaces. We show that wettability contrast surfaces align liquid water within patterned hydrophilic regions during the condensation process. Furthermore, this method could have a greater potential to align other liquids or living cells.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2004년도 춘계학술대회
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• pp.1576-1581
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• 2004

An experimental study has been carried out to investigate the frosting behaviors of thermally conductive plastic(PBT based resin) resin by comparing with those of aluminum and some plastic(PTFE based resin) test specimens. It is found that the frosting behavior of plastic specimens with 1 mm thickness show similar trend with aluminum except PTFE. The properties of frost formed on the specimens are affected by both thermal conductivityand surface characteristics (hydrophilic/hydrophobic) of the materials. It can be said that the heat and mass transfer rate of plastic materials are almost equivalent with those of aluminum.

• 한국생물공학회:학술대회논문집
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• 한국생물공학회 2002년도 생물공학의 동향 (X)
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• pp.581-584
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• 2002

Individual surface(hydrophilic/hydrophobic) were prepared and mammalian cells were cultured on the hydrophilic region. For drug test, cancer and normal cells were treated with Taxol, as an example. Our system was compared with MTT assay. CHO cells were resistant to Taxol up to 100 nM in both Methods. However, A549 cells was sensitive at 100 nM Taxol in the 2 day-treatment. Cervical carcinoma cell, HeLa, was very sensitive to Taxol. In our system, the cells were not shown from above 20 nM Taxol treatment. Our system was competitive to MTT assay in animal cells for drug test.

• 대한환경공학회지
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• 제22권7호
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• pp.1253-1261
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• 2000

천연유기물질은 지표수와 지하수내 탁도를 유발하고 humic (humic acid와 fulvic acid)과 nonhumic 성분으로 구성된다. 일반적으로 NOM은 소독부산물(DBP) 전구물질로써 수처리시 관심의 대상이 된다. 원수의 특성은 정수공정의 선택과 적용에 중요한 정보를 제공한다. 수원에 따른 NOM의 상당한 차이가 다양한 원수들 사이에서 관찰되었고, 문제시되는 NOM을 제거하고 전환시키기 위한 목적으로 정수공정을 적용한다. 본 연구의 결과, 산화처리에 의해 전체 DOC 농도의 변화는 거의 없었지만, 고분자의 소수성 물질이 저분자의 친수성 물질로 전환되었고, 염소보다 오존의 경우 그 산화력의 차이 때문에 SUVA 값의 감소가 더 크게 나타났다. 응집처리에 의해 hydrophilic 성분보다 분자량이 더 큰 hydrophobic 성분이 응집 침전되어 훨씬 잘 제거되었다. THMFP는 50% 정도까지 제거되었는데, 이것은 상대적으로 THMFP를 잘 유발시킨다는 humic acid 성분의 제거가 원활하게 일어났기 때문이다.

• 한국염색가공학회지
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• 제13권1호
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• pp.18-22
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• 2001

Effects of cationic surfactants old the wetting behavior of the DMDHEU treated cotton fibers were investigated using a technique based on the Wilhelmy principle. The results indicated that Interactions between the fiber and water ill the interface make contributions to wettability of the cotton fiber surface because of reorientation of polar groups at the interface. The effects of types and concentration of cationic surfactant on the wettability of both control and durable press(DP) finished cotton fiber are discussed. Below and near the critical micelle concentration(cmc), the adsorption of hexadecyltrimethylammoniumbromide(HTAB) on the control fiber makes the fiber surface more hydrophobic. Near and above the cmc of octadecyltrimethylammouniumbromide(OTAB) , the decrease in advancing contact angles indicates that the control cotton surface became hydrophilic. By the adsorption of both HTAB and OTAB onto the fiber surface, the hydrophobicity of the DP finished fiber surface became mere hydrophilic.