• Title/Summary/Keyword: Non-wetting

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Molecular Imprints in Nanostructured Polymer Surfaces - A New Generation of Biomimetic Materials for Chemical Sensors

  • Haupt, Karsten
    • Proceedings of the Polymer Society of Korea Conference
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    • 2006.10a
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    • pp.31-32
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    • 2006
  • We describe the preparation of nanostructured molecularly-imprinted surfaces using nanomolding on porous alumina. In molecular imprinting functional and cross-linking monomers are copolymerized in the presence of a molecular template, resulting in synthetic receptor materials. The drug propranolol and the dye fluorescein were used as the molecular imprinting templates. Binding studies with imprinted and non-imprinted surfaces revealed specific recognition of the templates and thus the existence of selective binding sites. In addition, the surface properties of the films were studied by water contact angle measurements. It was found that, depending on the monomers used, certain nanostructures induced great changes in the wetting properties of the surface.

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Tracking Resistance and UV Degradation Property of Polymeric Insulating Materials by Cross-Link Time (가교시간에 따른 고분자 재료의 트래킹성과 자외선 열화특성)

  • 천종욱;이운용;조한구
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 2002.07a
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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.

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Work/Family Conflict. Physical/Psychological Symptoms, and Life Satisfaction of Employed Homemakers in Dual-Earner Family. (기혼 취업 여성이 지각하는 가정 직업 생활갈등 및 부적응 증상과 생활만족)

  • 이운숙;이순형;유가효;조재순
    • Journal of Families and Better Life
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    • v.9 no.2
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    • pp.209-223
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    • 1991
  • The purpose of this study is to investigate work/family conflicts and its relationships with antecedent and outcome variables. 421 employed homemakers living in Seoul. Kyunggi-do , Chungju, and Daegu provided data using questionnaires. The results of path analysis showed that the level of work/family conflict was weakly correlated with demographic and managerial antecedents( age of respondent and standards for household task performance) but strongly correlated with work wetting characteristics, physical/psychological symptoms, and life satisfaction. A research model received considerable empirical support. this presumed that work/family conflict leads to negative outcomes, and was caused by the stress resulting form work setting and non-work conditions.

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Bioinspired Nanoengineering of Multifunctional Superhydrophobic Surfaces

  • Choi, Chang-Hwan
    • Proceedings of the Korean Institute of Surface Engineering Conference
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    • 2015.11a
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    • pp.102-133
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    • 2015
  • Nature, such as plants, insects, and marine animals, uses micro/nano-textured surfaces in their components (e.g., leaves, wings, eyes, legs, and skins) for multiple purposes, such as water-repellency, anti-adhesiveness, and self-cleanness. Such multifunctional surface properties are attributed to three-dimensional surface structures with modulated surface wettability. Especially, hydrophobic surface structures create a composite interface with liquid by retaining air between the structures, minimizing the contact area with liquid. Such non-wetting surface property, so-called superhydrophobicity, can offer numerous application potentials, such as hydrodynamic drag reduction, anti-biofouling, anti-corrosion, anti-fogging, anti-frosting, and anti-icing. Over the last couple of decades, we have witnessed a significant advancement in the understanding of surface superhydrophobicity as well as the design, fabrication, and applications of superhydrophobic coatings/surfaces/materials. In this talk, the designs, fabrications, and applications of superhydrophobic surfaces for multifunctionalities will be presented, including hydrodynamic friction reduction, anti-biofouling, anti-corrosion, and anti-icing.

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A Study of Rivulet Flow on an Inclined Solid Surface (경사면에서의 리뷸릿 유동에 관한 연구)

  • 김진호;김호영;강병하;이재헌
    • Korean Journal of Air-Conditioning and Refrigeration Engineering
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    • v.13 no.10
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    • pp.1042-1048
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    • 2001
  • When a liquid is supplied through a nozzle onto a relatively non-wetting inclined solid surface, a narrow rivulet forms. This work provides novel physical insights into the following phenomena in the rivulet flow that have not been well understood to date. Firstly, the fundamental mechanism behind the transition of a linear rivulet to a droplet flow is investigated. The experiments show that the droplet flow emerges due to the necking of a liquid thread near the nozzle. Based on the observation, it is argued that when the axial velocity of a liquid is slower than the retraction velocity of its thread, the bifurcation of the liquid thread occurs, and this argument is experimentally verified. Secondly, a discussion on the curled motion of a meandering rivulet is given. This study proposes the contact angle hysteresis as a primary origin of the centripetal force that enables the rivulet\`s curved motion. A simple scaling analysis based on this assumption predicts a radius of curvature which agrees with the experimental observation.

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An Experimental Study on the Seawater Resistance of Steel Fiber Reinforced Concrete (강섬유보강콘크리트의 내해수성에 관한 실험적 연구)

  • 박승범;오광진;장석호;이봉춘
    • Proceedings of the Korea Concrete Institute Conference
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    • 1997.04a
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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.

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A STUDY ON THE EFFECT OF UV LIGHT ABSORBER ON THE COLOR CHANCE OF MAXILLOFACIAL SILICONE (자외선 차단제가 악안면 실리콘의 색변화에 미치는 영향에 관한 연구)

  • Song, Yun-Seok;Lim, Ju-Hwan;Cho, In-Ho
    • The Journal of Korean Academy of Prosthodontics
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    • v.37 no.3
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    • pp.343-357
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    • 1999
  • The color change of maxillofacial silicone has been attributed to certain environmental factors such as exposure to the UV component of natural sunlight, wetting and drying of the elastomer and surface abrasion resulting from the application and removal of cosmetics. The purpose of this study was to evaluate the color change of maxillofacial silicone (Silastic MDX4-4210) according to type of pigment (cadmium yellow, titanium white, cosmetic red), and UV absorber application method after 200, 400, and 600 hours of 350nm UV light irradiation. The results were as follows. 1. According to type of pigments, after 200 hours cosmetic red showed significantly larger color change than cadmium yellow and titanium white, and after 400 and 600 hours color change significantly decreased in the order of cosmetic red, cadmium yellow, and titanium white (p<0.05). 2. In the cadmium yellow group, after 200 hours, the non-treatment group showed significantly larger color change, but after 400 and 600 hours, color change significantly decreased in the order of non-treatment, surface application and mixed group (p<0.05). 3. In the titanium white group, there was no significant color change difference between the three groups after 200 and 400 hours, but after 600 hours, the mixed group showed significantly smalt or color change than the non-treatment and surface application groups (p<0.05). 4. In the cosmetic red group, there was significant decrease in color change in the order of non-treatment, surface application and mixed group (p<0.05). From the results above, the effect of UV light absorber differed according to the type of pigment, but mixing UV light absorber with maxillofacial silicone is thought to give superior resistance against UV light irradiation in the long run.

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Shear bond strength of a layered zirconia and porcelain according to treatment of zirconia liner (치과용 지르코니아 이장재 처리에 따른 지르코니아와 도재의 전단결합강도 비교)

  • Seo, Jeong Il;Park, Won Uk;Kim, Yang Geun
    • Journal of Technologic Dentistry
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    • v.39 no.1
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    • pp.43-52
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    • 2017
  • Purpose: Physical and chemical properties of gold is most suitable to be restored of teeth to its original state. Recently zirconia was used instead of gold because of esthetical and intimacy of human body. Because of high strength and high abrasion resistance of zirconia, all zirconia artificial tooth lead to wear the original tooth of opposite site. To preserve this original tooth, zirconia artificial tooth covered with dental ceramic glass was used. When joining the zirconia core and dental ceramic glass, difference of their thermal expansion coefficient and wetting ability is generated the residual stress at interface lead to crack. In order to solve this problem, intermediate layer what is called zir-liner was imported to decrease the residual stress and increase the bonding strength. Methods: In this study, to identify the optimum conditions for manufacturing process, various methods to rough the surface of zirconia core were adopted, and vary the thickness of interlayer, and analyzed bond strength. Results: Bond strength of sanding specimens group showed higher than that of non-sanding specimens group, and once applied intermediate layer with sanding specimens showed highest bond strength with 28 MPa. SEM photomicrographs of zirconia cores fired at $1500^{\circ}C$ showed parallel straight lines in sanding and pockmarked surface in blasting surfaces as abrasion traces. Observation of the destruction section after shear test by SEM were carried out. Liner applied non-sanding group and non-liner applied sanding group all showed interfacial crack. Sandblasting group with non-liner showed remained dental ceramic glass on the surface of zirconia. Sandblasting group with once applied liner showed partially remained liner and dental ceramic glass on the surface of zirconia. XRD analysis revealed that sandblasting group showed higher monoclinic peaks than other specimens group and this result was due to the high collision energy for stress induced phase transformation. Conclusions: A study on the improvement of bonding strength between zirconia and dental ceramic glass steadily carried out for the future to practical use.

The Relationship between Lens Properties and the Lens Wearer's Factors in RGP Lens Manufacturing (RGP렌즈 제조 시 렌즈 물성과 렌즈 착용자 요인과의 관계)

  • Park, Mijung;Park, Ha Young;Park, Jung Ju;Kong, Heejung;Cha, Young Hwa;Kim, So Ra
    • Journal of Korean Ophthalmic Optics Society
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    • v.18 no.1
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    • pp.27-35
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    • 2013
  • Purpose: The present study was conducted to investigate the changes in the physical properties of RGP lenses induced by the polishing during the process of RGP lens manufacturing, and further evaluate the differences in the actual wearer's comfort and the tear film break-up time caused by these changes. Methods: RGP lenses (fluorosilicone acrylate material) were divided into 4 groups by the different lens-polishing time like 0, 25, 50 and 100 seconds and the thickness, the surface roughness and the wetting angle of those lenses were compared. Furthermore, the comfortability of the lens wear was surveyed after applying these lenses on the subject's eyes with normal tear volume and the non-invasive tear break-up time of the wearers was measured. Results: The central thickness of 4 RGP lenses made of different lens-polishing time was not significantly different however, the lens surface was changed smoother after polishing to be confirmed by scanning electron microscopy. The wetting angle of the RGP lens significantly decreased in accordance with the increase of polishing time. Thus, the difference of approximately $16^{\circ}$ between 0 second and 100 seconds-polishing was statistically significant. The actual wearing feeling of RGP lens was tended to improve in accordance with the increase of the lens wettability however, it was not proportional improvement. The non-invasive tear break-up time of the lens wearers showed different aspect compared with the changes in lens wettability and the actual feeling of RGP lens wear. Conclusions: In this study, better lens wettability, thinner lens thickness, and/or improved lens surface induced by physical stimuli in the process of RGP lens manufacturing was not well-correlated with the increase of actual subjective/objective satisfaction in RGP lens wear. Thus, the consideration of physical properties of the lens as well as the lens wearers' physiological factors in the process of RGP lens manufacturing may be suggested.

A Study on The Effect of Dampening Conductivity in the Offset Printing Printability (오프셋인쇄 축임물의 전도도가 인쇄적성에 미치는 영향에 관한 연구)

  • Park, Chan-Woo;Lee, Jae-Soo
    • Journal of the Korean Graphic Arts Communication Society
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    • v.25 no.1
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    • pp.43-52
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    • 2007
  • Offset printing is one of the well known printing technique of lithographic process and consists of image area and 'non-image area on a flat image carrier. The surface tension of dampening water can be controlled by adding IPA after mixing of raw water and etching solution. The etching solution contains a surfactant for reducing surface energy, a clean agent for non-imaging area, wetting agent for protecting non-imaging area from oil components like ink and also an emulsifying agent for controlling emulsification. In this study, the present situation of dampening water maintenance has examined by collecting dampening water using at domestic companies. The pH related to dampening water, conductivity, contact angle, emulsification curve are measured to define the current situation of dampening water control of each companies and to analyze the relationship among measured properties. In the study most of companies among 16 printing companies tested controlling dampening water through pH value. However, the quality of printing has varied depending upon conductivity, contact angle, IPA content, and emulsification value. The control of dampening water should be carry at the state of the standard when adding proper ratio of etching solution. It would be more effective when pH or conductivity control carries out in parallel with controlling dampening water. Therefore the concept that pH5.5 is correct is based concept. Based on these initial tests it is defined that the standardization of dampening water control is required.

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