• Title/Summary/Keyword: Materials property

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Surface structure modification of vertically-aligned carbon nanotubes and their characterization of field emission property

  • adil, Hawsawi;Jeong, Gu-Hwan
    • Proceedings of the Korean Vacuum Society Conference
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    • 2016.02a
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    • pp.159-159
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    • 2016
  • Vertically-aligned carbon nanotubes (VCNT) have attracted much attention due to their unique structural, mechanical and electronic properties, and possess many advantages for a wide range of multifunctional applications such as field emission displays, heat dissipation and potential energy conversion devices. Surface modification of the VCNT plays a fundamental role to meet specific demands for the applications and control their surface property. Recent studies have been focused on the improvement of the electron emission property and the structural modification of CNTs to enable the mass fabrication, since the VCNT considered as an ideal candidate for various field emission applications such as lamps and flat panel display devices, X-ray tubes, vacuum gauges, and microwave amplifiers. Here, we investigate the effect of surface morphology of the VCNT by water vapor exposure and coating materials on field emission property. VCNT with various height were prepared by thermal chemical vapor deposition: short-length around $200{\mu}m$, medium-length around $500{\mu}m$, and long-length around 1 mm. The surface morphology is modified by water vapor exposure by adjusting exposure time and temperature with ranges from 2 to 10 min and from 60 to 120oC, respectively. Thin films of SiO2 and W are coated on the structure-modified VCNT to confirm the effect of coated materials on field emission properties. As a result, the surface morphology of VCNT dramatically changes with increasing temperature and exposure time. Especially, the shorter VCNT change their surface morphology most rapidly. The difference of field emission property depending on the coating materials is discussed from the point of work function and field concentration factor based on Fowler-Nordheim tunneling.

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Evaluation of Antibacterial Property and Freshness Maintenance of Functional Hybrid Corrugated Board Used for Agricultural Products (농산물용 복합 골판지의 항균성 및 선도유지기능 평가)

  • Lee, Ji-Young;Kim, Chul-Hwan;Choi, Jae-Sung;Oh, Seok-Ju;Kim, Byeong-Ho;Lim, Gi-Baek;Kim, Sun-Young;Kim, Jun-Sik
    • Journal of Korea Technical Association of The Pulp and Paper Industry
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    • v.45 no.3
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    • pp.45-51
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    • 2013
  • We developed a new antibacterial material, a non-woven fabric, a sulfur solution, and a new adhesive system to manufacture a new type of functional hybrid corrugated board in previous studies. Based on experimental data, the prototypes of functional hybrid corrugated boards were manufactured and their physical properties and functionalities, including antibacterial property and the freshness maintenance of sweet persimmon, were measured in this study. The functional hybrid corrugated board could be manufactured in the actual process with linerboards, non-woven fabrics, and other materials without any troubles, and was strong enough to be used as a packaging box for agricultural products. The antibacterial property of the hybrid corrugated board showed a value high enough to eliminate bacteria, which could deteriorate the sweet persimmons. Based on appearance observations, weight loss and firmness measurements, the freshness of sweet persimmons in the functional hybrid corrugated board was maintained better than it was in the conventional corrugated board.

Polydopamine Coating Behaviors on the Acrylic Acid Grafted-Nanofibers (아크릴산이 그라프트된 나노섬유에서의 폴리도파민 코팅)

  • Shin, Young Min;Kim, Woo-Jin;Park, Jong-Seok;Gwon, Hui-Jeong;Nho, Young-Chang;Lim, Youn-Mook
    • Journal of Radiation Industry
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    • v.5 no.4
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    • pp.371-376
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    • 2011
  • The surface property of the materials used in tissue engineering application has been essential to regulate cellular behaviors by directing their adhesion on the materials. To modulate surface property of the synthetic biodegradable materials, a variety of surface modification techniques have used to introduced surface functional groups or bioactive molecules, recently polydopamine coating method have been introduce as a facile modification method which can be coated on various materials such as polymers, metals, and ceramics regardless of their surface property. However, there are no reports about the degree of polydopamine coating on the materials with different hydrophilicity. In the present study, we prepared acrylic acid grafted nanofibrous meshes using electron-beam irradiation, and then coated meshes with polydopamine. Polydopamine successfully coated on the all meshes, both properties of acrylic acid and polydopamine were detected on the meshes. In addition, the degree of polydopamine deposition on the materials has been altered according to surface hydrophilicity, which was approximately 8-times greater than those on the non-modified materials. In conclusion, dual effect from the acrylic acid grafting and polydopamine may give a chance as a alternative tool in tissue engineering application.

Inorganic Salt Doped Soluble Polyimide Type Alignment Layer for Improving Panel Reliability and DC Image Sticking Properties

  • Lee, Tae-Rim;Roh, Seung-Kwang;Lim, Young-Nam;Kim, Kyeong-Jin;Shin, Hyun-Ho
    • 한국정보디스플레이학회:학술대회논문집
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    • 2009.10a
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    • pp.672-676
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    • 2009
  • Polymide is widely used alignment material of recent commercial LCD panel structure. Generally, polyimide alignment material is classified soluble polyimide type and polyamic acid type with their main bond structure of solution state. specially, compared to polyamic acid alignment layer, soluble polyimide type alignment layer have excellent reliability during long term LCD driving cause of their high imidazation ratio(%), high voltage holding ratio(%) and low ion density. The other side, this type alignment materials has significant DC image stickicng side effect for using in-plane switching mode lcd structure cause of their slow DC discharging property. we applied inorganic salt to usual soluble polyimide type alignment layer and found out this technique had good DC image sticking property without any loss of reliability property in inplane switching LCD cell structure. This approach leads excellent DC image sticking property with maintaining high reliability property this approach confirmed improves an image sticking and a reliability simultaneously from the horizontality aligned LCD mode whose relatively bad image sticking property.

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Microstructure and Tribological Properties along with Chemical Composition and Size of Initial Powder in Fe-based BMG Coating through APS (대기 플라즈마 용사공정을 이용한 Fe계 벌크 비정질 금속 코팅의 초기 분말의 화학조성과 크기에 대한 미세 조직 및 마모 특성)

  • Kim, Jung-Hwan;Yoon, Sang-Hoon;Na, Hyun-Taek;Lee, Chang-Hee
    • Journal of the Korean institute of surface engineering
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    • v.41 no.5
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    • pp.220-225
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    • 2008
  • In this study, two kinds of Fe-based bulk metallic glasses (BMG) powder were built-up through atmospheric plasma spray (APS) technique. The microstructure of two coatings was analyzed through X-ray diffraction, scanning electron microscopy and transmission electron microscopy. Crystallization and oxidation in coatings were affected by chemical composition and initial powder size. Then, both of them influenced the tribological property.