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Kim, Doyoung,Ha, Min Woo,Hong, Suckchang,Park, Cheonhyoung,Kim, Byungsoo,Yang, Jewon,Park, Hyeung-geun American Chemical Society 2017 Journal of organic chemistry Vol.82 No.9
<P>A new efficient synthetic method for chiral alpha-azido-alpha-alkylmalonates and alpha-aryloxy-alpha-alkylmalonates was developed. The enantioselective alpha-alkylation of diphenylmethyl tert-butyl alpha-bromomalonate under phase-transfer catalytic conditions [(S,S)-3,4,5-trifluorophenyl-NAS bromide, 50% KOH, toluene, and -40 degrees C) provided the corresponding alpha-bromo-alpha-alkylmalonates in high chemical yields (<= 98%) and high optical yields (<= 99% ee). The resulting alpha-alkylated products were converted to alpha-azido-alpha-alkylmalonates <= 97% ee) and alpha-aryloxy-alpha-alkylmalonates (<= 79%, <= 93%, ee) by S(N)2 substitution with sodium azide and aryloxides, respectively.</P>
Ha, Min Woo,Lee, Jun Young,Kim, Doyoung,Lee, Geumwoo,Lee, Jae Kyun,Hong, Suckchang,Park, Hyeung-geun American Chemical Society 2018 Journal of organic chemistry Vol.83 No.2
<P>An efficient synthetic method for establishing chiral α-thio-α-quaternary stereogenic center was successfully developed. The enantioselective α-alkylation of α-acylthiomalonates under phase-transfer catalytic conditions [50% aq. KOH, toluene, −20 °C, and (<I>S</I>,<I>S</I>)-3,4,5-trifluorophenyl-NAS bromide] provided the corresponding α-acylthio-α-alkylmalonates in high chemical yields (up to 99%) and high optical yields (up to 98% ee).</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/joceah/2018/joceah.2018.83.issue-2/acs.joc.7b02605/production/images/medium/jo-2017-02605f_0010.gif'></P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/jo7b02605'>ACS Electronic Supporting Info</A></P>
FSI(Fluid-Structure Interaction) Analysis for Harmonious Operation of High-Speed Printing Machine
Jin-Ho Kim,Jae-Woo Lee,Soo Hyung Park,Doyoung Byun,Yung-Hwan Byun,Changjin Lee 한국항공우주학회 2008 International Journal of Aeronautical and Space Sc Vol.9 No.1
Proper amount of entrained air and nip force should be also considered to minimize ballooning phenomenon since tight contact between a roller and web is required. In this paper, various web materials, PET(Polyester) and OPP(Oriented Poly Propylene) have been selected and investigated to satisfy high-speed printing requirement. Several web speeds, web tensions, and temperature conditions are imposed on each web materials and the pressure and gap profiles as well as nip force have been calculated. Increase of both the winding roller radius and the incoming wrap angle is considered under proper taper tension at 500 m/min of rewinding roller. By solving coupled Reynolds equation and web deflection equation simultaneously, the fluid-structure interaction process has been developed and is applied to the rewinding roller to investigate the ballooning phenomenon which causes guiding problems in high-speed printing performance conditions. By adjusting the linear taper tension, stress distribution between rewinding webs can be remarkably reduced and stable pressure and gap profile with ignorable ballooning phenomenon have been found.