• Title/Summary/Keyword: embossing

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Liquid Crystal Alignment on Patterned Micro-grooved Polyimide Surfaces

  • Chiou, D.R.;Chen, L.J.;Lee, C.D.;Liu, H.M.
    • 한국정보디스플레이학회:학술대회논문집
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    • 2005.07a
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    • pp.774-777
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    • 2005
  • In this work, a soft embossing method is proposed to fabricate microgrooves on polyimide surfaces. Apply these resulting patterned micro-grooved polyimide surfaces as the liquid crystal alignment layers. The director of liquid crystal molecules aligns perfectly along the direction of microgrooves.

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Fabrication of high ordered nano-sphere array on curved substrate by nanoimprint lithography

  • Hong, Seong-Hun;Bae, Byeong-Ju;Lee, Heon
    • Proceedings of the Korean Institute of Surface Engineering Conference
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    • 2008.11a
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    • pp.127-127
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    • 2008
  • The replica of highly ordered nano-sphere array patterns were fabricated using hot embossing method. The polymer replica was coated with silcon dioxide layer and self-assembled monolayer. Using UV nanoimprint lithography with the template, highly ordered nano-sphere array patterns were clearly fabricated on curved substrate.

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Electrochemical Characterization of Porous Graphene Film for Supercapacitor Electrode (다공성 그래핀 필름의 슈퍼캐패시터 전극용 전기화학적 특성)

  • Choi, Bong Gill;Huh, Yun Suk;Hong, Won Hi
    • Korean Chemical Engineering Research
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    • v.50 no.4
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    • pp.754-757
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    • 2012
  • In this report, we fabricate the porous graphene films through embossing process and vacuum filtration method and demonstrate their superior electrochemical properties as supercapacitor electrode materials. Insertion/removal of polystyrene nanoparticles between the graphene sheets allows to provide pore structures, leading to the effective prevention of restacking in graphene films. As-prepared porous graphene films have a large surface area, a bicontinuous porous structures, high electrical conductivity, and excellent mechanical integrity. The electrochemical properties of the porous graphene films as electrode materials of supercapacitor are investigated by using aqueous $H_2SO_4$ and ionic liquid solution under three-electrode system. The porous graphene films exhibit a high specific capacitance (284.5 F/g), which is two-fold higher than that of packing graphene films (138.9 F/g). In addition, the rate capability (98.7% retention) and long-term cycling stability (97.2%) for the porous graphene films are significantly enhanced, due to the facilitated ion mobility between the graphene layers.

Fabrication and Modeling of Microlens Array by a Modified LIGA Process

  • Kim Dong Sung;Lee Hyun Sup;Yang Sang Sik;Lee Bong-Kee;Lee Sung-Keun;Kwon Tai Hun;Lee Seung S.
    • Proceedings of the Korean Society for Technology of Plasticity Conference
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    • 2003.04a
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    • pp.7-13
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    • 2003
  • Microlens arrays were fabricated using a novel fabrication technology based on the exposure of a PMMA (Polymethylmethacrylate) sheet to deep X-rays and subsequent thermal treatment. X-ray irradiation causes the decrease of molecular weight of PMMA, which in turn decreases the glass transition temperature and consequently causes a net volume increase during the thermal cycle resulting in a swollen microlens. A new physical modeling and analyses for micro lens formation were presented according to experimental procedure. A simple analysis based on the new model is found to be capable of predicting the shapes of micro lens which depend on the thermal treatment. For the replication of micro lens arrays having various diameters with different foci on the same surface, the hot embossing and the microinjection molding processes has been successfully utilized with a mold insert that is fabricated by Ni-electroplating based on a PMMA microstructure of micro lenses. Fabricated microlenses showed good surface roughness with the order of 1nm.

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Development of Traditional Cultural Products Using Persimmon Dyeing (감물염색을 활용한 전통 문화상품의 개발)

  • Lee, Eun-Jin;Kim, Sun-Kyung;Cho, Hyo-Sook
    • The Research Journal of the Costume Culture
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    • v.15 no.6
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    • pp.1053-1062
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    • 2007
  • This study purposed to restructure representative traditional patterns formatively, manufacture actual cultural products with traditional dyeing technique using persimmon, and commercialize the results of the research. Traditionally in Korea, the dying of natural fiber such as cotton, flax and silk with persimmon was called Galmul dyeing, and clothes made through Galmul dyeing were called Galot. Galot was very useful because it is strong, does not pick up dirt easily, dries easily, and is cool in summer. In addition, cloth dyed with persimmon becomes stiff, so it does not need to be starched or ironed after washing. Moreover, it does not transmit heat under direct rays and is highly air-permeable, so it is cool and useful for standing the heat. In this study, we used traditional persimmon dyeing technique, printing traditional patterns fit for contemporary people's aesthetic sense not through dip-dying but through printing. When persimmon dyeing is used in expressing patterns, it produces not only visual effect but also embossing effect due to the characteristic of persimmon that makes printed patterns stiff, so we can obtain unique texture distinguished from other printing methods. We chose seven motive patterns, which were lotus pattern symbolizing eternal life, peony pattern symbolizing wealth and rank and prosperity, character Su(壽) pattern widely used as a symbol of health, bird and cloud pattern in the Goryeo Dynasty, Sahapyeoeuisohwa(四合如意小花) pattern printed on brocade in the Goryeo Dynasty, lattice pattern, cloth pattern on wall paintings from the Period of the Three Kingdoms. From each pattern chosen as a motive was extracted unit patterns and the original pattern was restored using Adobe Illustrator. Restored patterns were restructured to be applied to cultural products fit for contemporary formative sense. Fabrics used in dyeing were cotton, linen, ramie, silk, and polyester. Although the same persimmon dyeing was applied, we produced different feelings of patterns using various fabrics and in some cases gold and silver powder was added for the effect of gloss in addition to the embossing of patterns. Using printed fabrics we manufactured tea pads, place mats, cushions, wrapping cloth for gifts, wallet, lampshades.

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The Luminous Intensity and Luminaire Efficiency Analysis of White LED as Luminaire types for General Lighting (조명용 백색 LED광원의 등기구 형태에 따른 광도 및 기구효율 분석)

  • Hwang, Myung-Keun;Huh, Chang-Su;Seo, Yu-Jin
    • Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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    • v.18 no.3
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    • pp.20-26
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    • 2004
  • In this paper, luminaire optical efficiency and luminous intensity according to array of HB(high brightness) white LED(light emitting diode) and globe types of luminaire were simulated by computer and made a comparative analysis. LEDs were arranged by square of 7ea X 7ea. LED space has been divided into 8.2mm, 10mm and 15mm that mean distances between luminous centers of LEDs, and luminaire globes were classified into 30mm and 50mm 묘묘 from luminous center of LEDs. Also the simulations were made with / without globe, globe types were specified by convex and embossing types of which sizes are 8.2mm and 5.0mm, So total 27 classes of simulation were performed. This paper is to help luminire development using LED light source called digital lighting of 21th century, by studying luminire effciency and luminous intensity of different types of globes.

Fabrication of PMMA Micro CE Chip Using IPA Assisted Low-temperature Bonding (IPA 저온 접합법을 이용한 PMMA Micro CE Chip의 제작)

  • Cha, Nam-Goo;Park, Chang-Hwa;Lim, Hyun-Woo;Cho, Min-Soo;Park, Jin-Goo
    • Korean Journal of Materials Research
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    • v.16 no.2
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    • pp.99-105
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    • 2006
  • This paper reports an improved bonding method using the IPA (isopropyl alcohol) assisted low-temperature bonding process for the PMMA (polymethylmethacrylate) micro CE (capillary electrophoresis) chip. There is a problem about channel deformations during the conventional processes such as thermal bonding and solvent bonding methods. The bonding test using an IPA showed good results without channel deformations over 4 inch PMMA wafer at $60^{\circ}C$ and 1.3 bar for 10 minutes. The mechanism of IPA bonding was attributed to the formation of a small amount of vaporized acetone made from the oxidized IPA which allows to solvent bonding. To verify the usefulness of the IPA assisted low-temperature bonding process, the PMMA micro CE chip which had a $45{\mu}m$ channel height was fabricated by hot embossing process. A functional test of the fabricated CE chip was demonstrated by the separation of fluorescein and dichlorofluorescein. Any leakage of liquids was not observed during the test and the electropherogram result was successfully achieved. An IPA assisted low-temperature bonding process could be an easy and effective way to fabricate the PMMA micro CE chip and would help to increase the yield.

Formation of Microlens Array via a Modified LIGA Process: Molding and Modeling (변형 LIGA 공정을 이용한 마이크로 렌즈 어레이 개발: 몰딩 및 모델링)

  • Kim, D. S.;Lee, H. S.;S. S. Yang;Lee, B.K.;Lee, S.K.;T. H. Kwon;Lee, S. S.
    • Proceedings of the Korean Society for Technology of Plasticity Conference
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    • 2003.05a
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    • pp.465-469
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    • 2003
  • Microlens arrays were fabricated using a novel fabrication technology based on the exposure of a PMMA (Polymethylmethacrylate) sheet to deep X-rays and subsequent thermal treatment. X-ray irradiation causes the decrease of molecular weight of PMMA, which in turn decreases the glass transition temperature and consequently causes a net volume increase during the thermal cycle resulting in a swollen microlens. A new physical modeling and analyses for microlens formation were presented according to experimental procedure. A simple analysis based on the new model is found to be capable of predicting the shapes of microlens which depend on the thermal treatment. For the replication of microlens arrays having various diameters with different foci on the same surface, the hot embossing and the microinjection molding processes has been successfully utilized with a mold insert that is fabricated by Ni-electroplating based on a PMMA microstructure of microlenses. Fabricated microlenses showed good surface roughness with the order of 1 nm.

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Development of Direct Surface Forming Process

  • Cho, Kwang-Hwan;Yoon, Kyung-Hwan
    • Proceedings of the Korean Society for Technology of Plasticity Conference
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    • 2003.04a
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    • pp.73-77
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    • 2003
  • The backlight unit(BLU) is used as a light source of TFT liquid-crystalline-display (TFT-LCD) module. In this backlight unit, one of important components is the light guide, which is usually made of transparent polymers. Currently the screen-printing method is mainly used for the light guide as a manufacturing process. However, it has limitation to the flexibility of three-dimensional optical design. In the present paper a new alternative manufacturing method for the light guide with low-cost is proposed. This manufacturing method is named as direct surface forming (DSF), which is very similar to the well-known hot embossing except for partial contact between mold and substrate. The results of this new manufacturing method are presented in terms of processing condition, dimensional accuracy, productivity, etc.

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