Papers by Jeoungyeon Hwang
러빙처리된 플렉시블 액정표시소자의 전기광학특성
전자빔증착법을 통한 SiOx 박막의 액정 배향 효과
Chromatic aberration corrected switchable optical systems
Chromatic aberrations of diffractive waveplate optics for imaging applications can be corrected f... more Chromatic aberrations of diffractive waveplate optics for imaging applications can be corrected for different switchable states. Different opportunities for lenses and prisms, and their limitations are discussed.
Liquid crystal alignment on inkjet printed and air-buffed polyimide with nano-grove surface
Journal of Physics D: Applied Physics, 2009
... Liquid crystal alignment on inkjet printed and air-buffed polyimide with nano-grove surface .... more ... Liquid crystal alignment on inkjet printed and air-buffed polyimide with nano-grove surface ... In fact, the pretilt angle of LC alignment depends on many parameters, namely, the micro-groove structure, ratio of the two PIs, anchoring strength and LC [11]. ...
Liquid Crystal Alignment Effect on Photopolymer Surface Using an Acrylate Unit Photopolymerized by a Photoinitiator
Japanese Journal of Applied Physics, 2003
Photoalignment materials of PGMAcr, poly[3-(acryloyloxy)-2-hydroxypropyl methacrylate] using an a... more Photoalignment materials of PGMAcr, poly[3-(acryloyloxy)-2-hydroxypropyl methacrylate] using an acrylate unit photopolymerized by a photo-initiator and PGMA4Ch, poly[3-(4-chalconyloxy)-2-hydroxypropyl methacrylate] using photodimerization by the chalcone group were synthesized. Also, the liquid crystal (LC) alignment capabilities on the photopolymer layers were studied. A good LC alignment with UV exposure on the PGMAcr surface can be obtained. However, LC alignment defects were observed on
Electro-Optical Characteristics of the Ion-Beam-Aligned Twisted Nematic Liquid Crystal Display on a Diamond-Like-Carbon Thin Film Surface
Japanese Journal of Applied Physics, 2002
Résumé/Abstract Liquid crystal (LC) alignment capabilities and the variation of pretilt angles wi... more Résumé/Abstract Liquid crystal (LC) alignment capabilities and the variation of pretilt angles with ion beam irradiation on diamond-like-carbon (DLC) thin films, and electro-optical (EO) performances of the ion-beam-aligned twisted nematic liquid crystal display (TN-LCD) ...
Liquid-Crystal Aligning Capabilities Using a New Photodimerization Method on a Poly (4'-methacryloyloxy chalcone) Surface
Japanese Journal of Applied Physics, 2000
Abstract The effects of liquid-crystal (LC) alignment and electro-optical (EO) characteristics of... more Abstract The effects of liquid-crystal (LC) alignment and electro-optical (EO) characteristics of photoaligned twisted-nematic (TN)-LC display (LCD) on a PMCh (poly (4'-methacryloyloxy chalcone)) surface using a new photodimerization method were investigated. ...
Liquid Crystal Alignment Effects and Electro Optical Performances of Twisted Nematic-Liquid Crystal Display Using Ion-Beam Alignment Method on Nitrogen-doped Diamond Like Carbon Thin Film Layer
Japanese Journal of Applied Physics, 2005
... Like Carbon Thin Film Layer. Authors: Park, Chang-Joon; Hwang, Jeoung-Yeon; Kang, Hyung-Ku; S... more ... Like Carbon Thin Film Layer. Authors: Park, Chang-Joon; Hwang, Jeoung-Yeon; Kang, Hyung-Ku; Seo, Dae-Shik; Ahn, Han-Jin; Kim, Jong-Bok; Kim, Kyung-Chan; Baik, Hong-Koo. Affiliation: AA(Department of Electrical and ...
Liquid Crystal Aligning Capabilities on New Photo-Crosslinkable Polyimide Based Polymer by the Photodimerization Method
Ferroelectrics, 2002
We studied the liquid crystal (LC) alignment and pretilt angle generation for a nematic (N) LC us... more We studied the liquid crystal (LC) alignment and pretilt angle generation for a nematic (N) LC using a photodimerization method on various new photo-crosslinkable polyimide based polymer. A good thermal stability of the photopolymers was measured by thermogravimatric analysis (TGA) measurement until 450°C. High pretilt angle of the NLC was obtained by polarized UV exposure on the photopolymers containing biphenyl (BP), decyl (de), and cholesteryl (chal) group, respectively. However, low pretilt angle of the NLC was measured by polarized UV exposure on the photopolymers containing fluorine and chalcone group. The high NLC pretilt angle generated is attributable to the biphenyl, alkyl moieties, and photodimerized chalcone group of the photopolymer. Also, a good the electro-optical (EO) characteristics in the TN-LCD photoaligned with UV exposure of 30θ on the photopolymer surface can be achieved.
Film Compensation of the Optically Compensated Splay Liquid Crystal Device
Molecular Crystals and Liquid Crystals, 2005
Optically compensated splay (OCS) mode, where the LCs are almost homeotropi-cally aligned with a ... more Optically compensated splay (OCS) mode, where the LCs are almost homeotropi-cally aligned with a rubbed parallel at both surfaces, and where a mid-director orients itself parallel to the substrate, is known to show a wide-viewing-angle, due to self-compensation effect. Since ...
Beam shaping diffractive waveplates
We present and discuss opportunities opened up by a new generation of beam shaping optical elemen... more We present and discuss opportunities opened up by a new generation of beam shaping optical elements that combine capabilities of digital spatial light polarization converters and diffractive properties of thin liquid crystalline films with patterned orientation of anisotropy axis (diffractive waveplates, DWs). Several functions of the new generation beam shapers are demonstrated, among them converting a laser beam of a Gaussian profile into a ring profile in the far field, a flattop profile, and into complex images. We also describe electrically controlled beam shaping optical elements which can be turned Off and On within milliseconds by applying a low external voltage. Optical, morphological and electro-optical properties of the components are characterized.
Transactions on Electrical and Electronic Materials
Transactions on Electrical and Electronic Materials
Transactions on Electrical and Electronic Materials
Journal of the Korean Institute of Electrical and Electronic Material Engineers
Alignment Properties and EO Performances of Flexible TN-LCD UsingIn-SituPhotoalignment Method with the Polymer Film
Molecular Crystals and Liquid Crystals
ABSTRACT We have investigated the generation of pretilt angle for a nematic liquid crystal (NLC) ... more ABSTRACT We have investigated the generation of pretilt angle for a nematic liquid crystal (NLC) alignment with in-situ photoalignment method on polyimide (PI) surfaces using polymer films. Especially, we studied in-situ photoalignment changing heating temperature from 50°C to 120°C on the polymer film. The LC aligning capabilities and pretilt angle on the polymer substrates were better than those on the glass substrate using in-situ photoalignment method. It is considered that this increase in pretilt angle may be attributed to the roughness of the micro-groove substrate induced by the in-situ photoalignment. As temperature of heated subtrate and UV exposure time increases, pretilt angle of the cell used polymer film increased. It is considered that the heating temperature of substrate is attributed to generate pretilt angle. Also, EO performances of the in-situ photoaligned TN cell using the polymer substrate are almost the same as that of the TN cell using the glass substrate.
Dual-function reversible/irreversible photoalignment material
Journal of Molecular Liquids
Abstract We report on new modification of visible sensitive SPAAD series photoalignment materials... more Abstract We report on new modification of visible sensitive SPAAD series photoalignment materials (BEAM Co) and a method of alignment/treatment to create a photoalignment layer that can be reversible or fixed in a polymerizable matrix. The irreversible state is stable to exposures with to visible as well as ultraviolet radiation.
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Papers by Jeoungyeon Hwang