• 제목/요약/키워드: Nano Science

검색결과 4,151건 처리시간 0.041초

Preparation and Characterizations of C60/Polystyrene Composite Particle Containing Pristine C60 Clusters

  • Kim, Jung-Woon;Kim, Kun-Ji;Park, Soo-Yeon;Jeong, Kwang-Un;Lee, Myong-Hoon
    • Bulletin of the Korean Chemical Society
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    • 제33권9호
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    • pp.2966-2970
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    • 2012
  • Fullerene/polystyrene ($C_{60}$/PS) nano particle was prepared by using emulsion polymerization. Styrene and fullerene were emulsified in aqueous media in the presence of poly(N-vinyl pyridine) as an emulsion stabilizer, and polymerization was initiated by water soluble radical initiator, potassium persulfate. The obtained nano particles have an average diameter in the range of 400-500 nm. The fullerene contents in the nano particle can be controlled up to 15 wt % by varying the feed ratio, which was confirmed by themogravimetric analysis (TGA) and elemental analysis (EA). The structure and morphologies of the $C_{60}$/PS nano particles were examined by various analytical techniques such as dynamic light scattering (DLS), scanning electron microscope (SEM), transmission electron microscope (TEM), electron diffraction (ED) pattern, X-ray powder diffraction (XRD), and UV spectroscopy. Unlike conventional $C_{60}$/PS particles initiated by organic free radical initiators, in which the fullerene is copolymerized forming a covalent bond with styrene monomer, the prepared $C_{60}$/PS nano particles contain pristine fullerene as secondary particles homogeneously distributed in the polystyrene matrix.

The effect of Sodium Concentrations on the Formation of Nanotubes Obtained from $TiO_2$

  • Qamar, M.;Lee, N.H.;Yoon, C.R.;Oh, H.J.;Kim, S.J.;Hwang, J.S.
    • 한국전기전자재료학회:학술대회논문집
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    • 한국전기전자재료학회 2006년도 추계학술대회 논문집 광주전남지부
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    • pp.123-125
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    • 2006
  • The $TiO_2$ sol was prepared hydrothermally in an autoclave from aqueous $TiOCl_2$ solutions as a starting precursor. Hollow fibers were obtained when the sol-gel-derived $TiO_2$ sol was treated chemically with a NaOH solution and subsequently heated in the autoclave under various conditions. A systematic analysis of the influence of different NaOH concentrations on the formation of nanotubes was carried out. The details of the nanotubular structure were investigated by using transmission electron microscopy (TEM), scanning electron microscopy (SEM) and X-ray diffraction (XRD). From the TEM images, the outer and the inner diameters of the tubes were measured to be about 8 and 4 nm, respectively, the lengths were measured to be several hundreds of nanometers.

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Anti-adipogenic Effects of Dongchimi Nano Juice in Mouse 3T3-L1 Adipocytes

  • Kong, Chang-Suk;Lee, Sun-Hyun;Seo, Jung-Ok;Park, Kun-Young;Rhee, Sook-Hee
    • Preventive Nutrition and Food Science
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    • 제11권4호
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    • pp.285-288
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    • 2006
  • The anti-adipogenic effect of dongchimi nano juice prepared using a nano-filtering process was investigated by measuring leptin and glycerol levels and the expression of a peroxisome proliferator-activated $receptor-\gamma\;(PPAR\gamma)$ gene as indicators of lipid accumulation or lipolysis. Red pepper powder, seeds of red pepper, garlic, and ginger were added in the preparation of dongchimi. Dongchimi was fermented to reach the optimal fermentation period, followed by nano-filtration in the range of $0.0005\sim0.1\;{\mu}m$. The lactic acid bacteria of dongchimi nano juice were removed completely by a nano-filtering process. Treatment of dongchimi nano juice induced glycerol release in the 3T3-L1 adipocytes and decreased the mRNA expression level of $PPAR\gamma$. These results suggested that dongchimi nano juice may enhance lipolysis and modulate adipogenesis in 3T3-L1 cells.

An Education Model of a Nano-Positioning System for Mechanical Engineers

  • Lee Dong-Yeon;Gweon Dae-Gab
    • Journal of Mechanical Science and Technology
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    • 제20권10호
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    • pp.1702-1715
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    • 2006
  • The increasing use of nano-positioners in a wide variety of laboratory and industrial applications has created a need for nano-mechatronics education in all engineering disciplines. The subject of nano-mechatronics is broad and interdisciplinary. This article focuses on the way nano-mechatronics is taught in department of mechanical engineering at Korea Advanced Institute of Science and Technology (KAIST). As one model of nano-positioning systems, design and experimental methodology is presented in this article. For design phase, the stiffness and resonant frequencies are found analytically and verified by using a commercial finite element analysis program. Next, for experimental phase, various tests are performed to access the performances of the designed nano-positioner, for example, sine-tracking, multi-step response and travel-range check etc. Finally, the definition of 'separation frequency' is described and some comments are discussed.

Abnormal Behavior in Color Tracking in the Fringe-Field Switching (FFS) Liquid Crystal Display

  • Jung, Jun-Ho;Ha, Kyung-Su;Chae, Mi-Na;Cho, In-Young;Kim, Woo-Il;Kim, Dae-Hyun;Kim, Sung-Min;Lee, Seung-Hee
    • 한국정보디스플레이학회:학술대회논문집
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    • 한국정보디스플레이학회 2009년도 9th International Meeting on Information Display
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    • pp.616-619
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    • 2009
  • Color tracking behavior of in the fringe-field switching (FFS) mode using a liquid crystal with positive dielectric anisotropy has been studied. In the in-plane switching and vertical alignment devices, color chromaticity at normal direction changes from bluish to yellowish white linearly with increasing grey levels from dark to white state. Interestingly, abnormal behavior in color tracking is observed in FFS devices using a liquid crystal with positive dielectric anisotropy, that is, it changes from bluish to yellowish up to a certain middle grey level but turns over to bluish white with further increasing from a grey level to a fully white state. In this paper, we analyze this abnormal effect from the calculated and experimental results.

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A 0.55" PDLC-LCoS Micro-display for Mobile Projectors

  • Do, Yun-Seon;Yang, Kee-Jeong;Sung, Shi-Joon;Kim, Jung-Ho;Lee, Gwang-Jun;Lee, Yong-Hwan;Chung, Hoon-Ju;Roh, Chang-Gu;Choi, Byeong-Dae
    • 한국정보디스플레이학회:학술대회논문집
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    • 한국정보디스플레이학회 2009년도 9th International Meeting on Information Display
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    • pp.1527-1530
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    • 2009
  • A LCoS micro-display using polymer dispersed liquid crystals (PDLCs) for light switching layer was fabricated. The Si backplane of SVGA ($800{\times}600$) with a pixel size of $14{\times}14mm^2$ was prepared by a $0.35{\mu}m$ 18V CMOS process. PDLCs were filled in the gap between backplane and ITO glass by conventional vacuum filling method. The prepared panels were driven by a field sequential color (FSC) scheme at the frequency of 180Hz and were successful in modulating LED lights to show projection images. The preparation and performance of PDLC-LCoS are presented.

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Development of Ceria-Based Slurry with High Selectivity for STI CMP

  • Lim, G.;Kim, T.E.;Kim, J.;Lee, J.H.;Lee, H.W.
    • 한국윤활학회:학술대회논문집
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    • 한국윤활학회 2002년도 proceedings of the second asia international conference on tribology
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    • pp.439-440
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    • 2002
  • Nano-Crystalline $CeO_2$ particles were dispersed in deionized water with controlled slurry chemicals for CMP test. According to the CMP test, the removal rate of $SiO_2$ layer was mainly controlled by the size and crystallinity of $CeO_2$ particles which can be controlled by the heat-treatment condition during $CeO_2$ synthesis. In contrast, the removal rate of $Si_3N_4$ layer was significantly influenced by the passivation reagent which protects the $Si_3N_4$ surface layer from excessive dissolution during CMP.

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