• Proceedings of the Korean Vacuum Society Conference
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• 2011.02a
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• pp.473-473
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• 2011

In recent years, organic thin film transistors OTFTs based on conductive-conjugated molecules have received significant attention. We report a fabrication of organic single crystal nanowires that made on Si substrates by liquid bridge-mediated nanotransfer molding (LB-nTM) with polyurethane acrylate (PUA) mold. LB-nTM is based on the direct transfer of various materials from a stamp to a substrate via a liquid bridge between them. In liquid bridge-transfer process, the liquid layer serves as an adhesion layer to provide good conformal contact and form covalent bonding between the organic single crystal nanowire and the Si substrate. Pentacene is the most promising organic semiconductors. However pentacene has insolubility in organic solvents so pentacene OTFTs can be achieved with vacuum evaporation system. However 6, 13-bis (triisopropylsilylethynyl) (TIPS) pentacene has high solubility in organic solvent that reported by Anthony et al. Furthermore, the substituted rings in TIPS-pentacene interrupt the herringbone packing, which leads to cofacial ${\pi}-{\pi}$ stacking. The patterned TIPS-Pentacene single crystal nanowires have been investigated by Atomic force microscopy (AFM), Transmission Electron Microscopy (TEM), X-Ray Diffraction (XRD), Scanning Electron Microscopy (SEM) and electrical properties.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.16 no.1
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• pp.63-69
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• 2017

The golden section search method is widely used to optimize a single design variable in many fields due to its superior advantages of search. In this paper, a new direct search method is proposed by modifying the search structure of the golden section search method; thus, it can be adapted in the optimization of a single design variable for the injection molding process. This proposed method is applied to determine an optimal gate position for the injection molding of a bezel of an automated teller machine for minimizing the injection pressure. Thus, an optimal gate position where the injection pressure is decreased by 4.5 MPa to that of the initial position was obtained with a small number of simulations. It is anticipated that the current proposed search method can be utilized as a practical tool for optimizing single variables for injection molding design.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2003.07b
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• pp.1135-1138
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• 2003

The transformer is major equipment in power receiving and substation facilities. Necessary conditions required for the transformer are compactness, lightness, high reliability, economic advantages, and easy maintenance. The pole-mount transformer installed in distribution system is acting direct role in supply of electric power and it is electric power device should drive for long term. Most of modem transformer are oil-filled transformer and accident is happening considerable. The mold transformers have been widely used in underground substations in large building and have some advantages in comparison to oil-transformer, that is low fire risk, excellent environmental compatibility, compact size and high reliability. In addition, the application of mold transformer for outdoor is possible due to development of epoxy resin. The mold transformer generally has cooling duct between low voltage coil and high voltage coil. A mold transformer made by one body molding method has been developed for small size and low loss. One body molding transformer needs some cooling method because heat radiation between each winding is difficult. In this paper, The thermal analysis of pole mount mold transformer with one body molding by duct condition is investigated and the test result of temperature rise is compared with simulation data.

• Journal of Powder Materials
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• v.20 no.5
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• pp.323-331
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• 2013

In this paper, two kinds of advanced powder processing techniques Metal Injection Molding (MIM) and Direct Laser Forming (DLF) are introduced to fabricate complex shaped Ti alloy parts which are widely used for medical and aerospace applications. The MIM process is used to strengthen Ti-6Al-4V alloy compacts by addition of fine Mo, Fe or Cr powders. Enhanced tensile strength of 1030 MPa with 15.1% elongation was obtained by an addition of 4 mass%Cr because of the microstructural modification and also the solution strengthening in beta phase. However, their fatigue strength was lower compared to wrought materials, but was improved by HIP. Subsequently, the effect of feeding layer height (FLH) on the characteristics of the DLF compacts was investigated. In the case of 100 ${\mu}m$ FLH, surface roughness was improved and nearly full density (99.8%) was obtained. Also, tensile strength of 1080 MPa was obtained, which is higher than the ASTM value.

• Proceedings of the Korean Vacuum Society Conference
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• 2011.02a
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• pp.464-464
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• 2011

We report a method to fabricate a large-area metal nanowire-grid polarizer. Liquid-bridge-mediated nanotransfer molding (LB-nTM) is based on the direct transfer of metal nanowires from a mold to a transparent substrate via liquid layer. A metal particle solution is used as an ink in the LB-nTM, which can be used for the formation of metal nanowires. The nanowires have higher depth are preferred for high transmittance. The height of nanowires that we made is about 140 nm. Large-area WGP is fabricated with good average transmittance of 74.89% in our measuring range.

• Proceedings of the Korean Vacuum Society Conference
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• 2012.02a
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• pp.537-537
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• 2012

We have studied a fabrication of vapor phase polymerized Poly(3,4-ethylenedioxythiophene) (PEDOT) nanowire arrays for the first time. The vapor-phase polymerization (VPP) technique is a bottom-up processing method that utilizes the organic arrangement of macromolecules to easily produce ordered aggregates, including on the nanoscale, or prepare thin films of self-assembled molecules, micropatterns, or modified microstructures of pure conducting polymers. Also, liquid-bridge-mediated nanotransfer molding (LB-nTM), which was reported as a new direct patterning method recently, is for the arrayed formation of two- or three-dimensional structures with feature sizes as small as tens of nanometers over large areas up to 4 inches across and is based on the direct transfer of various materials from a mould to a substrate through a liquid bridge between them. The PEDOT nanowires grown by VPP method and transferred on a substrate to use LB-nTM method have been fabricated to single crystal PEDOT nanowires investigated Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM), Selected Area Electron Diffraction (SAED), X-Ray Diffraction (XRD), X-ray Photoelectron Spectroscopy (XPS), and electrical properties.

• Proceedings of the Korean Vacuum Society Conference
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• 2010.02a
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• pp.83-83
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• 2010

We report a new direct printing method, called liquid-mediated nanotransfer molding (LB-nTM), that uses a polar liquid-mediated transfer process. LB-nTM is based on the direct transfer of various materials from a stamp to a substrate via a liquid- bridge between the stamp and the substrate. This procedure can be adopted in automated printing machines that generate various material patterns with a wide range of feature sizes (as small as 60 nm) on diverse substrates. To demonstrate its usefulness, the LB-nTM method was applied to prepare ZnO-nanowire and TIPS-pentacene transistors.

• Journal of the Korean Society of Environmental Restoration Technology
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• v.12 no.6
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• pp.76-85
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• 2009

This study was carried to select the proper vegetation base materials which improve soil quality in abandoned coal mine areas. Also, we aimed at the feasibility of the direct seeding method without soil molding for the ecological restoration in those areas. We set total eight plots within the study site established on an abandoned coal mine area near Taebaek city, Gangwon province in April 2006. The plots were classified as two groups(straw mats mulching and no mulching), and the four treatments (C; control, MI; microbial innoculation, WC; wood chip, OF; organic fertilizer) were applied in each two groups for the soil conditioning. The survival of Pinus densiflora was highest among other species(Betula platyphylla var. japonica, Amorpha fruticosa and Arundinella hirta). For the non straw mat, the survival rate of Pinus densiflora seedlings was highest in the WC treatment($1,756trees/m^2$). For the straw mat, survival rate of Pinus densiflora seedlings was also highest in the WC treatment ($1,622trees/m^2$). In addition, for the non straw mat, the height growth of Pinus densiflora seedling was highest in the OF treatment($12.4{\pm}3.9cm$). For the straw mat, the height growth of Pinus densiflora seedling was also highest in the OF treatment($18.7{\pm}5.3cm$). In general, organic fertilizer treatment with the straw mat was most effective for seedling growth. Also, we suggested that the direct seeding method without soil molding could be sufficiently possible for revegetating abandoned coal mine, Korea.

• Proceedings of the Korean Vacuum Society Conference
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• 2010.08a
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• pp.287-287
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• 2010

We report a new direct patterning method, called liquid bridge-mediated nanotransfer molding (LB-nTM), for the formation of two- or three-dimensional structures with feature sizes between tens of nanometers and tens of micron over large areas. LB-nTM is based on the direct transfer of various materials from a mold to a substrate via a liquid bridge between them. This procedure can be adopted for automated direct printing machines that generate patterns of functional materials with a wide range of feature sizes on diverse substrates. Arrays of TIPS-PEN TFTs were fabricated on 4" polyethersulfone (PES) substrates by LB-nTM using PDMS molds. An inverted staggered structure was employed in the TFT device fabrication. A 150 nm-thick indium-tin oxide (ITO) gate electrode and a 200 nm-thick SiO2dielectric layer were formed on a PES substrate by sputter deposition. An array of TIPS-PEN patterns (thickness: 60 nm) as active channel layers was fabricated on the substrate by LB-nTM. The nominal channel length of the TIPS-PEN TFT was 10 mm, while the channel width was 135 mm. Finally, the source and drain electrodes of 200 nm-thick Ag were defined on the substrate by LB-nTM. The TIPS-PEN TFTs can endure strenuous bending and are also transparent in the visible range, and therefore potentially useful for flexible and invisible electronics.

• 한국신재생에너지학회:학술대회논문집
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• 2005.06a
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• pp.248-251
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• 2005

Graphite reinforced conductive polymer composites for PEMFC bipolar plates were fabricated by the compression molding technique. Graphite powder was mixed with an phenol resin to impart electrical property in composites. In this study, conductive polymer composites with high filler $loadings(>60wt.\%)$ were manufactured to accomplish high electrical conductivity above 100S/cm. The level of compaction is important because graphite powder increase electrical conductivity of composites by direct physical contact between particles. The optimum molding pressure according to filler was proposed experimentally. Various tests(electrical conductivity, flexural strength, compressive strength, leach test, etc) were carried out to verify the performance of fabricated composites for PEMFC bipolar plates. Fabricated composites have good electrical conductivity and mechanical strength. The results of leach test and contact angle measurement showed similar characteristics compared with commercial bipolar plates.