• Food Science and Biotechnology
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• 제16권2호
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• pp.234-237
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• 2007

Water resistance of three biopolyester films, such as poly-L-lactate (PLA), poly-hydroxybutyrate-co-valerate (PHBV), and Ecoflex, and low density polyethylene (LDPE) film was investigated by measuring contact angle of various probe liquids on the films. The properties measured were initial contact angle of water, dynamic change of the water contact angle with time, and the critical surface energy of the films. Water contact angle of the biopolyester films ($57.62-68.76^{\circ}$) was lower than that of LDPE film ($85.19^{\circ}$) indicating biopolyester films are less hydrophobic. The result of dynamic change of water contact angle also showed that the biopolyester films are less water resistant than LDPE film, but much more water resistant than cellulose-based packaging materials. Apparent critical surface energy for the biopolyester films (35.15-38.55 mN/m) was higher than that of LDPE film (28.59 mN/m) indicating LDPE film is more hydrophobic.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2002년도 하계학술대회 논문집
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• pp.447-450
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• 2002

Recently polymeric insulators and arresters are being used for outdoor high voltage applications. Polymeric insulators for transmission line have significant advantages over porcelain and glass insulators, especially for ultra-high voltage(UHV) transmission lines. Their advantages are light weight, vandalism resistance and hydrophobicity. Polymeric insulator kind are a relatively new technology, but their expected life is still unknown. In this paper, the material property for polymeric insulating material such as silicone rubber and EPBM is investigated by cross-link time and the relation between tracking resistance and W resistance is analyzed by IEC 60587 and W aging experiment.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 1997년도 봄 학술발표회 논문집
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• pp.315-322
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• 1997

This paper describes an experimental study on the seawater resistance of steel fiber reinforced concrete. The test method adopted for this study may be devided into long-term immersion test and accelerated test by wetting and drying. Test were carried out to evaluate the procedure in which reduction in dynamic modulus, length change and compressive strength to nine months were measured. Resistance indicators are the water - cement ratio, the content of steel fiber, the immersion water(artificial seawater or freshwater). The conditions of intervals of immersing in artificial seawater and drying, low water-cement ratio, and non-steel fiber became most deteriorated.

• 콘크리트학회지
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• 제9권3호
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• pp.189-197
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• 1997

본 연구에서는 보통의 일반콘크리트와 플라이애쉬를 혼입한 강섬유보강 콘크리트의 해수에 대한 저항성을 고찰하기 위하여 수행되었다. 콘크리트 배합 인자를 물.시멘트비, 강섬유혼입률, 플라이애쉬 혼입률별로 각각 제조하였으며, 표준수(수도물)와 인공으로 제조한 해수에 장기간 침지한 경우와 건조와 습윤의 반복작용에 의한 촉진시험으로 시험을 수행하여 콘크리트의 성능저하에 미치는 영향을 비교.고찰하였다. 시험방법은 소정의 재령에 각각의 배합조건별로 압축강도와 재령 1일을 기준으로 길이변화와 동탄성계수를 측정하여 성능저하정도를 비교분석하였다. 그 결과 강섬유와 플라이애쉬의 적정량의 혼입은 콘크리트의 내해수성을 현저히 개선시키는 효과를 나타내었다.

• Fibers and Polymers
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• 제3권4호
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• pp.174-178
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• 2002

A plasma treatment using saturated $CF_4$ gas was employed to improve the resistance of polypropylene fabrics to water wetting. The fabrics were significantly fluorinated even within a short treatment time of 30 seconds. The result of contact angle measurement indicated that such highly hydrophobic surface was considerably durable even after 150 days of aging.

• 폴리머
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• 제32권4호
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• pp.313-321
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• 2008

UV개시에 의해 광경화형 아크릴 공중합체를 합성하고 제조된 아크릴 점착제(PSA)의 박리 에너지와 물리적 특성을 조사하였다. 이때 acrylic acid(AA)의 함량을 변화시켜 점착제의 물성을 변화시켰으며, 피착제의 표면 거칠기, 표면 요철방향, 점착제의 두께를 변화시킴으로써 박리 에너지의 변화 추이를 조사하였다. 공단량체인 acrylic acid의 함량이 증가함에 따라 표면 거칠기가 낮은 피착제가 높은 박리 에너지를 보였으며 점착제의 두께가 두꺼워 질수록 증가하였다. 또한 피착제 표면의 요철방향이 박리방향과 수평일 때 특히 높은 박리 에너지를 갖는 것으로 나타났다. 이것은 점착제의 두께 감소와 피착제 표면 거칠기의 증가가 wetting의 감소를 초래하지만 박리 시 저항력은 오히려 증가하는 경향을 나타내기 때문일 것이라는 예상과도 잘 일치한다.

• 한국유체기계학회 논문집
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• 제13권2호
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• pp.5-11
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• 2010

The nanofluidics is characterized by a large surface-to-volume ratio, so that the surface properties strongly affect the flow resistance. We present here the results showing that the effect of wetting properties and the surface roughness may considerably reduce the friction of fluid past the boundaries. For a simple fluid flowing over hydrophilic and hydrophobic surfaces, the influences of surface roughness are investigated by the nonequilibrium molecular dynamics (NEMD) simulations. The fluid slip at near a solid surface highly depends on the wall-fluid interaction. For hydrophobic surfaces, apparent fluid slips are observed on smooth and rough surfaces. The solid wall is modeled as a rough atomic sinusoidal wall. The effects on the boundary condition of the roughness characteristics are given by the period and amplitude of the sinusoidal wall. It was found that the slip velocity for wetting conditions at interface decreases with increasing effects of surface roughness. The results show the surface rougheness and wettability determines the slip or no-slip boundary conditions. The surface roughness geometry shows significant effects on the boundary conditions at the interface.

• 한국재료학회지
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• 제3권5호
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• pp.529-537
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• 1993

TiC 입자를 강화재로 한 AI금속기지 복합재료를 액상교반법으로 제조하는데 따른 제조조건과 물성특성과의 관계를 조사하였다. TiC 입자는 중량비 10%를 첨가하였으며, 젖음성을 향상시키기 위하여 1.5wt%의 Mg을 첨가하였다. TiC입자 첨가에 의하여 내마모 특성, 인장강도, 경도 등이 증가 되었으나 과도한 교반은 기계적 특성을 저하시켰다. 본 실험조건에서 교반 속도의 최적조건은 500rpm이었다. Wetting agent로서 첨가한 Mg은 기지에 고루 분산하였다.

• 대한토목학회논문집
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• 제41권3호
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• pp.219-227
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• 2021

불연속 지형을 지나는 천수 흐름을 해석할 수 있는 Hwang의 기법이 채택된 수치 모의를 댐 붕괴 흐름에 의한 직립 홍수터의 범람 실험과 비교하였다. 모의 결과는 저수지, 저수로, 홍수터로 이루어진 실험 수로에서 측정한 결과와 잘 일치하였다. 특히, 댐 붕괴 흐름이 직립 홍수터로 차고 빠지는 과정이 잘 모의되었다. 흐름 저항의 종류에 따른 모의 결과의 차이는 미미하였다. 이 연구를 바탕으로 도심 하천의 범람 예측에서 정확도를 높일 수 있을 것으로 기대된다.

• 한국표면공학회지
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• 제56권1호
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• pp.1-11
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• 2023

Lubricant-impregnated nanoporous surfaces (LIS), which is created by impregnating water-immiscible oil into nanoporous surface structure, have been explored considering wide range of application fields. Due to the lubricant impregnated in nanoporous structure, the surface shows extreme de-wetting with a high mobility of water droplets, so that various functionalities can be realized. The lubricant layer inhibits the contact of corrosive media to porous structure as well as metal substrate, thus the surface improves the corrosion resistance. The water on the surface freeze without any contact to solid porous structure, showing a low ice adhesion for de-icing an anti-icing. The extremely high mobility of water droplets on lubricant-impregnated porous surfaces also contributes the enhancement of condensation heat transfer as well as water harvesting from fog and moisture. Moreover, the bacteria adhesion on metal surface forming biofilms causing serious hygiene issues can be inhibited on the lubricantimpregnated surfaces. Despite of such superior functionalities, the lubricant-impregnated porous surface has a limitation of lubricant depletion by external flow of fluids. Therefore, extensive efforts to improve the durability of lubricant-impregnated surface are required for practical applications.