• Title/Summary/Keyword: side chain

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Progress of Study on Mesogen-Jacketed Liquid Crystalline Polymers at Peking University

  • Fan, Xing-He;Chen, Xiao-Fang;Wan, Xin-Hua;Chen, Er-Qiang;Zhou, Qi-Feng
    • Proceedings of the Polymer Society of Korea Conference
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    • 2006.10a
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    • pp.90-90
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    • 2006
  • Mesogen-Jacketed Liquid Crystalline Polymers, MJLCPs, are polymers with mesogenic side groups directly attached to main-chains without using flexible connecting spacers and are able to form liquid crystalline structures. Later work on structure-property of the polymers revealed that the side groups are not necessarily mesogenic for the polymers to form a mesophase so long as that the side groups are directly attached to the backbones and the side groups are large enough. Because of its inherent chain stiffness and that the monomers of MJLCPs are readily polymerizable by "living" free radical polymerizations, MJLCP offered a unique handy tool for making block copolymers. In addition, MJLCP offered also new opportunities for novel functional materials.

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Effect of Liquid Crystal alignment in the cell using transcription alignment method (전사배향법을 이용한 씰의 액정배향의 효과)

  • 서대식;김진호;최재학
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 1998.06a
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    • pp.271-274
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    • 1998
  • In this paper, the monodomain alignment of nematic liquid crystal(NLC) in the cell fabricated by one side transcription alignment method on PI surface with side chain were investigated. The LC alignment produced by the transcription alignment method is attributable to a memory effect of the NLC on Pl surfaces. We observed that the pretilt angle of NLC is generated about 3.6$^{\circ}$ in a cell with one side transcription alignment on PI surface. Also, the electro-optical(EO) performance of TN-LCD with one side transcription alignment method on PI surface will be discussed.

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Dynamic Analysis of Multi-Robot System Forcing Closed Kinematic Chain (복수로봇 시스템의 동력학적 연구-대상물과 닫힌 체인을 형성할때의 문제-)

  • 유범상
    • Transactions of the Korean Society of Mechanical Engineers
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    • v.19 no.4
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    • pp.1023-1032
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    • 1995
  • The multiple cooperating robot system plays an important role in the research of modern manufacturing system as the emphasis of production automation is more on the side of flexibility than before. While the kinematic and dynamic analysis of a single robot is performed as an open-loop chain, the dynamic formulation of robot in a multiple cooperating robot system differs from that of a single robot when the multiple cooperating robots form a closed kinematic chain holding an object simultaneously. The object may be any type from a rigid body to a multi-joint linkage. The mobility of the system depends on the kinematic configuration of the closed kinematic chain formed by robots and object, which also decides the number of independent input parameters. Since the mobility is not the same as the number of robot joints, proper constraint condition is sought. The constraints may be such that : the number of active robot joints is kept the same as mobility, all robot joints are active and have interrelations between each joint forces/torques, two robots have master-slave relation, or so on. The dynamic formulation of system is obtained. The formulation is based on recursive dual-number screw-calculus Newton-Eulerian approach which has been used for single robot analysis. This new scheme is recursive and compact symbolically and may facilitate the consideration of the object in real time.

The Effects of Logistics Service Quality and Relationship Orientation on Supply Chain Performance - Focusing on Delivery Quality of 3PL Firms - (물류서비스품질과 관계지향성이 공급사슬성과에 미치는 영향 - 3PL 기업의 물류배송품질을 중심으로 -)

  • Park, Yi-Suk;Cho, Geon;Ryu, Il
    • Journal of Korean Society for Quality Management
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    • v.37 no.3
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    • pp.102-122
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    • 2009
  • In this study, we will conduct an empirical study to see how the 3PL firm's logistics service quality and relationship orientation affects the supply chain performance. To examine the research model and hypotheses, we have used an empirical method based on the field survey in which most of measurements used and verified in previous studies are selected as measurements. The results of our empirical study can be summarized as follows: First, it can be shown that higher level of logistics service quality not only affects satisfaction and relationship orientation positively, but also improves supply chain performance. Second, it can be also shown that satisfaction for logistics service quality affects relationship orientation between shipper and 3PL firm positively. Finally, it can be shown that relationship orientation affects supply chain performance positively. This paper presents much implications both theoretical and practical side.

Thermotropic Liquid Crystalline Behavior of [4-{4'-(Nitrophenylazo)phenoxycarbonyl}]alkanoated Celluloses ([4-{4'-(니트로페닐아조)펜옥시카보닐}]알카노화 셀룰로오스들의 열방성 액정 거동)

  • Jeong, Seung-Yong;Ma, Yung-Dae
    • Polymer(Korea)
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    • v.33 no.1
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    • pp.58-66
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    • 2009
  • The thermotropic liquid crystalline behavior of the homologous series of cellulose tri[4-{4'-(nitrophenylazo) phenoxycarbonyl}] alkanoates (NACEn, n=2$\sim$8, 10, the number of methylene units in the spacer) have been investigated. All of the homologoues formed monotropic nematic phases. The isotropic-nematic transition temperature ($T_{iN}$) decreased when n is increased up to 7, but it became almost constant when n is more than 7. The plot of transition entropy at $T_{iN}$ against n had a sharp negative inflection at n=7. The sharp change at n=7 may be attributed to the difference in arrangement of the side groups. The melting temperature ($T_m$) and associated entropy change at $T_m$, in contrast with $T_{iN}$ and associated entropy change at $T_{iN}$, exhibited a distinct odd-even effect, suggesting that the average shape of the side chains in the crystalline phase is different from that in the nematic phase. The thermal stability and degree of order of the nematic phase observed for NACEn were significantly different from those reported for the homologous series of side-chain and combined type liquid crystal polymers bearing azobenzene or biphenyl units in the side chains. The results were discussed in terms of the differences in the chemical structure, the flexibility of the main chain, the mode of chemical linkage of the side group with the main chain, and the number of the mesogenic units per repeating unit.

A Study on the Design of Upward and Downward Traverse Units in an Automatic Object Changer Unit to Establish a Flexible Production System (Part 1) (유연생산 시스템 구축을 위한 공작물 자동교환 유닛의 상하 이송 기구 설계에 관한 연구(파트 1))

  • Park, Hoo-Myung;Kang, Jin-Kab;Lee, Yong-Joong;Ha, Man-Kyung
    • Journal of the Korean Society of Manufacturing Process Engineers
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    • v.7 no.2
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    • pp.45-51
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    • 2008
  • The objective of this study is to develop an automatic object changer unit to improve processing problems existed in the conventional horizontal machining center. In order to perform this objective, a upward and downward traverse unit in which a unit that consists of a motor and reducer, chain and sprocket wheel, and upper and lower base employed in an automatic object changer unit performs sliding contact motion in a frame was designed. To achieve this design, constraint conditions for the upward and downward traverse unit first designed. Then, an operation mechanism was designed and that was introduced as a sum of kinetic energy for the sprocket wheel and upper and lower base based on the moment of inertia, which is the kinetic energy of the converted upward and downward traverse unit in the side of the reducer. In addition, The work required to rotate the converted upward and downward traverse unit in the side of the reducer by one revolution can be calculated using the sum of work that is required in the sprocket wheel and upper and lower base that is a part of the upward and downward traverse unit. Furthermore, the converted equation of motion in the side of the motor can be introduced using the equation of motion using the converted upward and downward traverse unit in the side of the motor. Then, Then, a proper motor can be determined using predetermined specifications employed in the motor and several parameters in the upward and downward traverse unit in order to verify such predetermined specifications. Also, a design of a horizontal traverse unit that performs sliding motion on a upward and downward traverse unit and simulation that verifies the results of this design are required as a future study.

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A Study on Liquid Crystal Alignment Effect on a Photopolymer Layer Based N-(phenyl)maleim ids Containing Three Kind of the Substituent (3가지 종류의 치환기를 함유한 N-(phenyl)maleimide계 광폴리머 표면을 이용한 액정 배향 효과에 관한 연구)

  • 황정연;이윤건;서대식;김준영;김태호
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
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    • v.15 no.3
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    • pp.264-268
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    • 2002
  • Three types of polymer, a photoalignment material based N- (phenol)maleimide were synthesized and the liquid crystal (LC) aligning capabilities on the photopolymer layer were studied. A good LC alignment with UV exposure on the PMI5CA(N-(phenol)maleimide with 5-carbon chain cinnamoyl group) can be obtained. However, the LC alignment defects were observed on the PM13CA (N-(phenol)maleimide with 3-carbon chain cinnamoyl group) and PMIF (N-(phenyl)maleimide including fluoro cinnamoyl group). Also, the good LC alignment with UV exposure on the PM15CA surface was observed at until $150^{\circ}C$ of annealing temperature. The LC aligning ability on the photopolymer layer based N-(phenol)maleimide depends on the side chain length of photopolymer.

Structural Analysis of Conductive Polypyrroles Synthesized in an Ionic Liquid

  • Song, Eun-Ah;Jung, Woo-Gwang;Ihm, Dae-Woo;Kim, Jin-Yeol
    • Bulletin of the Korean Chemical Society
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    • v.30 no.5
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    • pp.1009-1011
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    • 2009
  • Nano-structured conducting polypyrroles were synthesized in the ionic liquids (ILs) based on 1-alkyl-3-methylimidazolium family with tetrachloroferrate as an anion ($C_n\;mim\;[FeCl_4]\;with\;n\;=\;4,\;8,\;and\;12$). The polypyrrole nanostructures synthesized in ILs were formed as spherical shapes. For ionic liquids with alkyl side chain length $C_4,\;C_4\;mim\;[FeCl_4]$, the size of particles was ranged around 60-nm with a relatively narrow size distribution. As the length of alkyl chain increases, the particle sizes become larger and their distributions become wider. The self-assembled local structures in the solvent ionic liquids are likely to serve as templates of highly organized nano-structured polymers. The length of the alkyl chain in ionic liquids seems to affect these local structures.

A Study on Perception of Risk Factor in Supply Chain - Focus on Distribution Center - (공급사슬에서 존재하는 위험(Risk)요소의 인지에 관한 연구 - 물류센터를 중심으로 -)

  • Shin, Chang-Hoon;Jeoung, Dong-Hun;Choi, Min-Seung
    • Proceedings of the Korean Institute of Navigation and Port Research Conference
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    • 2005.10a
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    • pp.269-274
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    • 2005
  • This study gathered the factor of supply chain risk through literature review, and measured the importance of risk factors which have been recognized by domestic companies. This study has purposes and necessities as follows. First, supply risk factors were classified and explored through positive studies about supply chain risk. Most of previous studies helps grasping the meaning of supply chain risk but limited in conceptual side. Second, this study used AHP(Analytic Hierarchy Process) method which makes decision-making problem classified, simplicated and systematized to evaluate the importance of supply-chain risk recognized by the companies. Finally, this study suggests registration-point in companies's efficient supply activity would be great by measuring the importance of supply-chain through AHP(Analytic Hierarchy Process).

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