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Synthesis and Properties of Novel Photosensitive Copolymers Having Photoreactive Pendant Group
Chae, Heon Seung,Park, Yun Heum TaylorFrancis 2007 Molecular Crystals and Liquid Crystals Vol.472 No.1
<P> The novel photopolymers having photoreactive pendant group were designed and synthesized through the reaction between precursor, poly(methacrylic acid-co-2-hydroxyethyl methacrylate-co-styrene)(poly(MAA-HEMA-STY)) and photoreactive compounds such as methacryloyl chloride (MAC), cinnamoyl chloride (CC), methacryloyl isocyante (MAI) and 3-isopropenyl-α, α-dimethylbenzyl isocyanate (TMI), respectively. The prepared poly(MAA-HEMA-STY) and novel photopolymers were characterized by 1H-NMR and FT-IR spectroscopy. The photosensitivity of photopolymers was estimated with the UV exposing time by FT-IR spectra change at 1630 cm-1. The photosensitivity of photoresists was determined by calculating the UV energy at the pattern-remaining step after developing the thin film using gray-scale mask. In connection with the photosensitivity the surface hardness and compression properties of photopolymer films were determined by nano indenter. All prepared photopolymers revealed higher surface hardness than poly(MAA-HEMA-STY). Photopolymers with methacryloyl functional side group showed better photosensitivity than photopolymers with vinyl aromatic and cinnamoyl group. Especially photopolymer prepared from poly(MAA-HEMA-STY) and MAI showed good potential for the application of negative-working photoresist.</P>
Chae, Heon Seung,Park, Yun Heum TaylorFrancis 2007 Molecular Crystals and Liquid Crystals Vol.463 No.1
<P> In order to study the effect of glass transition temperature (Tg) on the compression and elastic recovery properties of polymer, several poly(meth)acrylate copolymers having three or four segment units composed of methacrylic acid (MAA) and other vinyl monomers such as glycidyl methacrylate (GMA), styrene (STY), butyl acrylate (BAM), 2-hydroxyethyl methacrylate (HEMA), methyl methacrylate (MMA), benzyl methacrylate (BzMA), 2-ethylhexyl acrylate (EHA), octadecyl acrylate (ODA), ethyl acrylate (EAM), and lauryl methacrylate(LMA) were synthesized. The synthesized copolymers showed different glass transition temperatures depending on the component type. Thin films and micro patterns were prepared by photolithography process (spin coating/pre-baking/UV-exposure/KOH developing/post-baking) with prepared copolymer solution. The compression and recovery property of copolymer films and micro patterns were determined by nano indenter. As a result, copolymers with lower Tg especially MAA/GMA/STY, MAA/GMA/STY/BAM, and MAA/GMA/STY/HEMA copolymers showed higher compression and elastic recovery ratio.</P>
인공지능 및 ICT 융합 기술을 활용하여 요추부 토크 추정 연구
채승헌(Seung Heon Chae),문호세(Jose Moon),허현무(Hyun Mu Heo),최안렬(Ahnryul Choi),문정환(Joung Hwan Mun) 한국통신학회 2021 한국통신학회 학술대회논문집 Vol.2021 No.6
본 연구는 ICT 융합의 센서 및 인공지능을 활용하여 들기 작업 시 발생하는 요추부 모멘트를 추정하였다. 근골격계 질환이 없는 성인 남성 9 명을 대상으로 Squat, Stoop 2 가지 동작에 대해 실험을 진행하였다. 인공지능 모델은 시계열 데이터 예측에 좋은 성능을 보이는 LSTM 모델을 사용하여 요추부 모멘트를 예측하는 모델을 구성하였다. 인공지능 모델은 상관계수 0.95 이상 RMSE 0.300 이하 결과를 보였다.
Chae, Oh B.,Kim, Jisun,Park, Inchul,Jeong, Hyejeong,Ku, Jun H.,Ryu, Ji Heon,Kang, Kisuk,Oh, Seung M. American Chemical Society 2014 Chemistry of materials Vol.26 No.20
<P>A vanadium pentoxide electrode is prepared in the amorphous form (<I>a</I>-V<SUB>2</SUB>O<SUB>5</SUB>), and its electrode performances are compared to those for its crystalline counterpart (<I>c-</I>V<SUB>2</SUB>O<SUB>5</SUB>). The <I>a</I>-V<SUB>2</SUB>O<SUB>5</SUB> electrode outperforms <I>c-</I>V<SUB>2</SUB>O<SUB>5</SUB> in several ways. First, it is free from irreversible phase transitions and Li trapping, which evolve in <I>c</I>-V<SUB>2</SUB>O<SUB>5</SUB>, probably due to the lack of interactions between the inserted Li<SUP>+</SUP> ions/electrons and V<SUB>2</SUB>O<SUB>5</SUB> matrix. Second, the absence of Li trapping allows a reversible capacity amounting to >600 mA h g<SUP>–1</SUP>, which is larger than that given by <I>c-</I>V<SUB>2</SUB>O<SUB>5</SUB>. Third, it shows an excellent rate property. The notably high reversible capacity and rate capability seem to be due to Li storage at vacant sites that are ill-defined but numerous in <I>a</I>-V<SUB>2</SUB>O<SUB>5</SUB>, which Li<SUP>+</SUP> ions can easily access. However, irreversible capacity of <I>a</I>-V<SUB>2</SUB>O<SUB>5</SUB> is appreciable in the first cycle due to a parasitic Li reaction with surface hydroxyl groups. Treatment with <I>n</I>-butyllithium can suppress the irreversible capacity by removing the surface hydroxyl groups.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/cmatex/2014/cmatex.2014.26.issue-20/cm502268u/production/images/medium/cm-2014-02268u_0011.gif'></P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/cm502268u'>ACS Electronic Supporting Info</A></P>
Chae, Seulki,Lee, Jeong Beom,Lee, Jae Gil,Lee, Tae-jin,Soon, Jiyong,Ryu, Ji Heon,Lee, Jin Seok,Oh, Seung M. Elsevier 2017 Journal of Power Sources Vol.370 No.-
<P><B>Abstract</B></P> <P>Vinylene carbonate (VC) is attached in a ring-opened form on a graphite surface by molecular layer deposition (MLD) method, and its role as a solid electrolyte interphase (SEI) former is studied. When VC is added into the electrolyte solution of a graphite/LiNi<SUB>0.5</SUB>Mn<SUB>1.5</SUB>O<SUB>4</SUB> (LNMO) full-cell, it is reductively decomposed to form an effective SEI on the graphite electrode. However, VC in the electrolyte solution has serious adverse effects due to its poor stability against electrochemical oxidation on the LNMO positive electrode. A excessive acid generation as a result of VC oxidation is observed, causing metal dissolution from the LNMO electrode. The dissolved metal ions are plated on the graphite electrode to destroy the SEI layer, eventually causing serious capacity fading and poor Coulombic efficiency. The VC derivative on the graphite surface also forms an effective SEI layer on the graphite negative electrode via reductive decomposition. The detrimental effects on the LNMO positive electrode, however, can be avoided because the bonded VC derivative on the graphite surface cannot move to the LNMO electrode. Consequently, the graphite/LNMO full-cell fabricated with the VC-attached graphite outperforms the cells without VC or with VC in the electrolyte, in terms of Coulombic efficiency and capacity retention.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Ring-opened VC is chemically bonded on graphite surface through MLD method. </LI> <LI> The attached VC copies reduction behavior of VC as additives generating SEI via C=C. </LI> <LI> VC-attached graphite outperforms the pristine graphite in both half cell and full cell. </LI> <LI> VC molecules added in electrolyte generate acid when oxidized. </LI> <LI> The acid generated by VC oxidation accelerates transition metal dissolution from LNMO. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>