• Title/Summary/Keyword: PUA

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A Study to Evaluate Performance of Poly-Urethane Polymer Concrete for Long-Span Orthotropic Steel Bridge (장경간 강바닥판 케이블교량에 적용하기 위한 폴리우레탄 폴리머콘크리트의 공용특성 연구)

  • Park, Heeyoung;Lee, Junghun;Kwak, Byeongseok;Choi, Iehyun;Kim, Taewoo
    • International Journal of Highway Engineering
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    • v.15 no.1
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    • pp.1-9
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    • 2013
  • PURPOSES: The purpose of this study is to evaluate physical properties, durability, fatigue resistance, and long-term performance of poly-urethane concrete (PU) which can be possible application of thin layer on long-span orthotropic steel bridge and to check structural stability of bridge structure. METHODS : Various tests of physical properties, such as flexural strength, tensile strength, bond strength and coefficient of thermal expansion tests were conducted for physical property evaluation using two types of poly urethane concrete which have different curing time. Freezing and thawing test, accelerated weathering test and chloride ion penetration test were performed to evaluate the effect of exposed to marine environment. Beam fatigue test and small scale accelerated pavement test were performed to assess the resistance of PU against fatigue damage and long-term performance. Structural analysis were conducted to figure out structural stability of bridge structure and thin bridge deck pavement system. RESULTS: The property tests results showed that similar results were observed overall however the flexural strength of PUa was higher than those of PUb. It was also found that PU materials showed durability at marine environment. Beam fatigue test results showed that the resistances of the PUa against fatigue damage were two times higher than those of the PUb. It was found form small scale accelerated pavement test to evaluate long-term performance that there is no distress observed after 800,000 load applications. Structural analysis to figure out structural stability of bridge structure and thin bridge deck pavement system indicated that bridge structures were needed to increase thickness of steel deck plate or to improve longitudinal rib shape. CONCLUSIONS: It has been known that the use of PU can be positively considered to thin layer on long-span orthotropic steel bridge in terms of properties considered marine environment, resistance of fatigue damage and long-term performance.

A Study on the Debinding Process of High Purity Alumina Ceramic Fabricated by DLP 3D Printing (DLP 3D 프린팅으로 제작된 고순도 알루미나 세라믹 탈지 공정 연구)

  • Lee, Hyun-Been;Lee, Hye-Ji;Kim, Kyung-Ho;Ryu, Sung-Soo;Han, Yoonsoo
    • Journal of Powder Materials
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    • v.27 no.6
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    • pp.490-497
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    • 2020
  • The 3D printing process provides a higher degree of freedom when designing ceramic parts than the conventional press forming process. However, the generation and growth of the microcracks induced during heat treatment is thought to be due to the occurrence of local tensile stress caused by the thermal decomposition of the binder inside the green body. In this study, an alumina columnar specimen, which is a representative ceramic material, is fabricated using the digital light process (DLP) 3D printing method. DTG analysis is performed to investigate the cause of the occurrence of microcracks by analyzing the debinding process in which microcracks are mainly generated. HDDA of epoxy acrylates, which is the main binder, rapidly debinded in the range of 200 to 500℃, and microcracks are observed because of real-time microscopic image observation. For mitigating the rapid debinding process of HDDA, other types of acrylates PETA, PUA, and MMA are added, and the effect of these additives on the debinding rate is investigated. By analyzing the DTG in the 25 to 300℃ region, it is confirmed that the PETA monomer and the PUA monomer can suppress the rapid decomposition rate of HDDA in this temperature range.

Synthesis of UV Curable Polyurethane Adhesives Based on Various Compositions of Mixed Polyol with Improved Adhesion and Flexural Properties (다양한 조성의 혼용 폴리올에 기초한 접착력 및 굴곡성이 향상된 자외선 경화형 폴리우레탄 접착제의 합성)

  • Won-Young Lee;Soo-Yong Park;Guni Kim;Ildoo Chung
    • Journal of Adhesion and Interface
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    • v.23 no.4
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    • pp.137-143
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    • 2022
  • In this study, the polyurethane acrylates (PUA) resin with good adhesive and flexibility for adhesive for shoes and clothing were synthesized using that poly(tetramethylene adiphate glycol) (PTAd), poly(tetramethylene ether glycol) (PTMG) as polyester polyol and polyether polyol respectively, including 4,4'-methylene diphenyl diisocyanate (MDI), isophorone diisocyanate (IPDI), 1,4-butandiol (1,4-BD), 2-hydroxyethyl methacrylate (2-HEMA) and dibutyl amine (DBA). The effect of polyol blend in the polyurethane acrylate on thermal and mechanical properties, adhesion strength and flexural strength were studied. The glass transition temperature (Tg) of PUA was confirmed in range of -70~-40 ℃. In addition, the glass transition temperature (Tg), decomposition temperature (Td), tensile strength adhesion strength and heat resistance were increased as increasing of PTAd amount while the elongation, water resistance and flexural properties were decreased. The synthesized polyurethane acrylate with 5:5 ratio of PTAd and PTMG indicated the highest adhesion strength and flexural properties.

Fabrication of micro/nanoscale hierarchical structures and its application (마이크로/나노 계층구조 형성법 및 응용)

  • Jeong, Hoon-Eui;Kwak, Rho-Kyun;Lee, Seung-Seok;Suh, Kahp-Yang
    • Proceedings of the KSME Conference
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    • 2007.05a
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    • pp.426-428
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    • 2007
  • A simple method is presented for fabricating micro/nanoscale combined hierarchical structures using a two-step UV-assisted capillary molding technique. This lithographic method consists of two steps: (i) fabrication of partially cured polymer microstructures using a PDMS mold and (ii) subsequent nanofabrication using a high-resolution polyurethane acrylate (PUA) mold on top of the pre-formed microstructures. Using this technique, various micro/nano hierarchical structures were fabricated with minimum resolution down to 70 nm over a large area with very good reproducibility.

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A Study on Advanced Lithium-Ion Battery with Polyurethane-Based Gel Polymer Electrolyte (Polyurethane기 겔폴리머전해질을 이용한 Advanced Lithium-Ion Battery에 관한 연구)

  • 김현수;문성인;윤문수;김상필
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 2002.07a
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    • pp.252-254
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    • 2002
  • In this study, polyurethane acrylate macromer was synthesized and it was used in a gel polymer electrolyte, and then its electrochemical performances were evaluated. LiCoO$_2$/GPE/MCF cells were also prepared and their performances depending on discharge currents and temperatures were evaluated. ionic conductivity of the gel polymer electrolyte with PUA at room temperature and -20$^{\circ}C$ was ca. 4.5 x 10$\^$-3/ S/cm and 1.7${\times}$10$\^$-3/ S/cm, respectively. GPE was stable electrochemically up to 4.5 V vs. Li/Li$\^$+/. LiCoO$_2$/GPE/MCF cell showed a good high-rate and a low-temperature performance.

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Breathable Waterproof Finish of PET Fabrics via Microporous UV Coating of Polyurethane Diacrylate (폴리우레탄 디아크릴레이트의 미세다공성 UV코팅에 의한 PET 직물의 투습방수가공)

  • Koo, Gwang-Hoe;Jang, Jin-Ho
    • Textile Coloration and Finishing
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    • v.22 no.3
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    • pp.239-245
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    • 2010
  • Breathable waterproof PET fabrics were prepared by the UV coating of UV-curable polyurethaneacrylate(PUA) formulation mixed with polyethyleneglycol(PEG) as a water soluble pore former. The dispersed PEG in the UV-cured coating was extracted by warm water, which can generate individual circular pores uniformly distributed all over the coating instead of pore channels. Accordingly the moisture permeability of the microporously coated fabrics increased substantially with increasing PEG addition without significant reduction of hydrostatic pressure. Also the silicone diacrylate addition in the formulation was beneficial in increasing the hydrostatic pressure. The UV-based microporous coating can be an alternative to conventional thermal curing of solventborne polyurethane coating owing to the enhanced environment friendliness and energy saving.

Fabrication of 6, 13-bis(triisopropylsilylethynyl) (TIPS) pentacene -Nanowire Arrays Using Nano Transfer Molding

  • Oh, Hyun-S.;Sung, Myung-M.
    • Proceedings of the Korean Vacuum Society Conference
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    • 2010.08a
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    • pp.284-284
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    • 2010
  • We report a fabrication of 6, 13-bis(triisopropylsilylethynyl) (TIPS) pentacene nanowires that made on Si substrates by liquid bridge-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 TIPS-pentacene nanowire and the Si substrate. The patterned TIPS-Pentacene nanowires have been investigated by Atomic force microscopy (AFM), Transmission Electron Microscopy (TEM), Scanning Electron Microscopy (SEM) and electrical properties.

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Enumeration and Activity of Methanogenic Microorganisms of th Anaerobic Digestion Process

  • Lee, Kwang-Ho
    • Korean Journal of Hydrosciences
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    • v.2
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    • pp.115-126
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    • 1991
  • The anaerobic digester with sludge from sewage treatment plant was operated in the laboratory for two year to investigate the enumeration and activity of methanogenic microorganisms. In this experimental study, the effects of HRT on the degradation characteristics of organic materials and on the number of methanogenic bacteria produced were investigated. By making the media with the repeated wxperiment, the number and activity of methanogenic bacteria were measured. The increase of the removal rate of organic acid in the digester was oberved at HRT of 2 days. The total number of methane forming bacteria estimated by the MPN method showed 2.3 $\times$ $ at HRT of 3 days, 7$\times$$ of 5 days and 7.9$\times$$ $/ml of 10 days. The optimum incubation time for measuring the number of methanogenic bacteria was found as more than four weeks. The PMA revealed 161ml CH$/l day at HRT of 10 days and the PUA 290mg COD/l day. At the incubation time 4.3 days, the maximum value of CH$ *59.1%) was found. At this time, $ was found as 15.3% and $ 25.6%.

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Stem cell behaviors on periodic arrays of nanopillars analyzed by high-resolution scanning electron microscope images

  • Jihun Kang;Eun-Hye Kang;Young-Shik Yun;Seungmuk Ji;In-Sik Yun;Jong-Souk Yeo
    • Applied Microscopy
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    • v.50
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    • pp.26.1-26.3
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    • 2020
  • The biocompatible polyurethane acrylate (PUA) nanopillars were fabricated by soft lithography using three different sizes of nanobeads (350, 500, and 1000 nm), and the human adipose-derived stem cells (hASCs) were cultured on the nanopillars. The hASCs and their various behaviors, such as cytoplasmic projections, migration, and morphology, were observed by high resolution images using a scanning electron microscope (SEM). With the accurate analysis by SEM for the controlled sizes of nanopillars, the deflections are observed at pillars fabricated with 350- and 500- nm nanobeads. These high-resolution images could offer crucial information to elucidate the complicated correlations between nanopillars and the cells, such as morphology and cytoplasmic projections.

Capillary-driven Rigiflex Lithography for Fabricating High Aspect-Ratio Polymer Nanostructures (모세관 리소그라피를 이용한 고종횡비 나노구조 형성법)

  • Jeong, Hoon-Eui;Lee, Sung-Hoon;Kim, Pil-Nam;Suh, Kahp-Y.
    • Journal of the Korean Society of Visualization
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    • v.5 no.1
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    • pp.3-8
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    • 2007
  • We present simple methods for fabricating high aspect-ratio polymer nanostructures on a solid substrate by rigiflex lithography with tailored capillarity and adhesive force. In the first method, a thin, thermoplastic polymer film was prepared by spin coating on a substrate and the temperature was raised above the polymer's glass transition temperature ($T_g$) while in conformal contact with a poly(urethane acrylate) (PUA) mold having nano-cavities. Consequently, capillarity forces the polymer film to rise into the void space of the mold, resulting in nanostructures with an aspect ratio of ${\sim}4$. In the second method, very high aspect-ratio (>20) nanohairs were fabricated by elongating the pre-formed nanostructures upon removal of the mold with the aid of tailored capillarity and adhesive force at the mold/polymer interface. Finally, these two methods were further used to fabricate micro/nano hierarchical structures by sequential application of the molding process for mimicking nature's functional surfaces such as a lotus leaf and gecko foot hairs.