• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1996.05a
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• pp.232-234
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• 1996

We have investigated the effect of molecular structure of polymer of rubbed polyimide (PI) films for surface liquid crystal alignment. To obtain surface alignment effect of Polymer molecular structure, we measured the polar (out of plane-tilt) anchoring strength and surface ordering of 5CB on rubbed PI surfaces. We have found that the polar anchoring strength of 5CB is depend on the polymer molecular structure of these unidirectionally rubbed PI surfaces.

• 한국정보디스플레이학회:학술대회논문집
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• 2004.08a
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• pp.766-768
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• 2004

Rubbed films of a series of poly(p-phenylene 3,6-bis(4-(n-alkyloxy)phenyloxy)pyromellitimide)s (Cn-PMDA-PDA PIs), which are well-defined brush PIs composed of two aromatic-aliphatic bristles per repeat unit of a fully rodlike backbone, were investigated in detail using atomic force microscopy (AFM), optical retardation analysis and linearly polarized infrared (IR) spectroscopy in order to elucidate their surface morphology and molecular orientation. The liquid crystal (LC) alignment behavior and the anchoring energy of LC molecules on the rubbed films were also determined.

• 한국정보디스플레이학회:학술대회논문집
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• 2006.08a
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• pp.611-614
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• 2006

Sum-frequency vibrational spectroscopy (SFVS) has been used to study the molecular orientations at the polymer surfaces for liquid crystal alignment. Various molecular orientations appear at the surface depending on various types of surface treatments and polymers.

• 한국정보디스플레이학회:학술대회논문집
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• 2004.08a
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• pp.1167-1168
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• 2004

Polarized ultraviolet irradiation techniques have been developed recently to produce alignment of liquid crystals (LC). Because of the excellent thermal stability and the alignment ablility of polyimides, polyimides has attracted considerable research interest for the photoinduced alignment layer. Hasegawa and Taira confirmed homogeneous alignment of LC by the decompostion of a polyimide induced by lineraly ultra-violet polarized light. It was reported that ultraviolet visible absorption spectra of a polyimide alignment film showed a remarkable change upon irradiation. In this study, we synthesized phthalic polyimide and a naphthalenic polyimide in order to investigate the effect of the polyimide structure. Some difference in terms of the photo-induced molecular orientaion of liquid crystals were observed with the polyimide structure.

• 한국정보디스플레이학회:학술대회논문집
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• 2009.10a
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• pp.948-950
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• 2009

A few organosilicon compounds (OC) - both cyclic and linear siloxanes with different structure of the substituents - have been synthesized. Properties of the LC anchoring on OC films have been measured. The OC investigated provide the homogeneous planar alignment with LC tilt angle in the range from $0.7^{\circ}$ to $1.9^{\circ}$. An increase of the microrelief depth results in a small increase of the tilt angle. The azimuthal anchoring is better for the films of the OC without molecular microrelief or the OC comprising polar groups.

• Korean Journal of Microbiology
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• v.35 no.2
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• pp.115-120
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• 1999

Multiple Sequence Alignment of DNA and protem sequences is a imnport'mt tool in the study of molecular evolution, gene regulation. and prolein suucture-function relationships. Progressive pairwise alignment method generates multiple sequence alignment fast but not necessarily with optimal costs. Dynamic programming generates multiple sequence alig~~menl with optimal costs in most cases but long execution time. In this paper. we suggest genetlc algorithm lo improve the multiple sequence alignment generated from the cnlent methods, describe the design of the genetic algorithm, and compare the multiple sequence alignments from 0111 method and current methods.

• Bulletin of the Korean Chemical Society
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• v.23 no.4
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• pp.587-592
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• 2002

Photocrosslinkable chalcone-epoxy compound comprising 1,3-bis-(4-hydroxy-phenyl)-propenone was synthe-sized for fabricating the photo-alignment layer of liquid crystals. Chalcone group was introduced into the main chain unit of the epoxy oligomer. We observed a photodimerization behavior and an optical anisotropy of this material by irradiation of a linearly polarized UV(LP-UV) light. With a trace amount of cationic photoinitiator (TRS-HFA), polymerization of epoxy groups was also conducted at the similar wavelength range used for photodimerization. Linearly polarized UV irradiation on the chalcone-epoxy films with cationic photoinitiator induced optical anisotropy of the film and the resultant film can be used for alignment layers for low molecular weight nematic liquid crystals.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.11 no.4
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• pp.306-313
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• 1998

To elucidate the liquid crystal(LC) molecules alignment mechanism, it is important to determine the molecular orientation of the rubbed polymer surface molecules that directly contact with LC molecules. In this work, the molecular orientation on a rubbed surface of polyimide (SE-3310, Nissan) film has been studied by polarized FTIR absorption spectroscopy. It has been found that molecular chain on the rubbed surface of polymide film are oriented along the rubbing direction and are tilted up on an average by 5.0$^{\circ}$. In the SHG(Second Harmonic Generation) measurement, the pretilt angle of molecular chain on the poylmide fim was 4.6$^{\circ}$ fro, the surface plane. And the pedit angle of liquid crystal (ZLI-2293, Merck) molecules measured by crystal rotation method was 5.4$^{\circ}$in the same rubbing condition.

• The Transactions of the Korean Institute of Electrical Engineers
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• v.43 no.2
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• pp.303-311
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• 1994

Optimum conditions for the deposition of N-docosylquinolium-TCNQ ultrathin organic films using the Langmuir-Blodgett etchnique and the molecular orientation and alignment of the LB films were studied. The $\pi$-A isotherm of the N-docosylquinolium-TCNQ was measured at the air-water interface varying with the subphase temperature, subphase pH, compressing speed and amounts of solutions for spreading. The LB film was deposited under the surface pressure of 30mN.m and 45mN/m and other deposition conditions. The molecular orientation and alignment of the LB films were studied by the polarization absorption technique. The $\pi$-A isotherm showed that the stable N-docosylquinolium -TCNQ monolayer was formed on the water surface at the condition of 25$^{\circ}C$,pH 5.6, molecular density of 2.1${\times}$10S014T~2.6${\times}$10S014T/cmS02T. The LB film was deposited under the surface pressure of 45mN/m had better packing density, orientation and alignment than the film of 30mN/m.

• Electrical & Electronic Materials
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• v.10 no.1
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• pp.68-75
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• 1997

본 해설에서는 평판 디스플레이 소자중의 하나인 LCD의 액정배향기술에 관하여 해설하였다. 액정배향은 LCD의 전기광학특성을 좌우하는 매우 중요한 기술이다. LCD 소자에 있어서 기판의 표면 위에 액정분자를 배열시키는 기술은 현재 러빙법이 주로 사용되고 있지만 러빙을 하지 않는 넌러빙법을 이용한 액정배향기술이 강하게 요구되고 있으며 향후 LCD에 있어서 보다 중요한 역할을 할 것으로 기대되고 있으며 고성능 LCD의 실현에는 필수 불가결한 기술로 생각된다.