• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2009년도 하계학술대회 논문집
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• pp.32-33
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• 2009

We propose viewing angle switchable liquid crystal display(LCD) associated with fringe-field switching (FFS) mode with high aperture ratio characteristic. This device is composed of R(red), G(green), B(blue), pixel and W(white) pixel in which R,G,B pixel shows image and white pixel for both viewing angle control and image. Conventional viewing angle controllable liquid crystal display has not transmittance because the liquid crystal only tilts up without rotates in viewing angle control region. In this paper, we suggested that the device has high transmittance characteristic because the LC directors are rotated in which viewing angle control region are generated fringe electric field.

• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2008년도 International Meeting on Information Display
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• pp.1386-1389
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• 2008

Conventional viewing angle switching electrode requires pixel division and additional liquid crystal panel. Hence the conventional viewing angle switching has low aperture ratio and high thickness. In this paper we proposed new viewing angle switching using hybrid aligned nematic mode by fringe-field electrode field (named HAN-FFS) with single liquid crystal panel. The fringe-field switching electrode is located at the bottom, and the additional common electrode is located at the top of the cell to control viewing angle. The proposed device is free from additional liquid crystal panel and pixel division. Consequently, the suggested structure has not only high aperture ratio but also show an excellent potential for viewing angle switching.

• 한국결정성장학회:학술대회논문집
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• 한국결정성장학회 1996년도 The 9th KACG Technical Annual Meeting and the 3rd Korea-Japan EMGS (Electronic Materials Growth Symposium)
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• pp.139-156
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• 1996

The phase field model is becoming the model of choice for the theoretical study of the morphologies of crystals growth from the melt. This model provides an alternative approach to the solution of the classical (sharp interface) model of solidification by introducing a new variable, the phase field, Ø, to identify the phase. The variable Ø takes on constant values in the bulk phases and makes a continuous transition between these values over a thin transition layer that plays the role of the classically sharp interface. This results in Ø being governed by a new partial differential equation(in addition to the PDE's that govern the classical fields, such as temperature and composition) that guarantees (in the asymptotic limit of a suitably thin transition layer) that the appropriate boundary conditions at the crystal-melt interface are satisfied. Thus, one can proceed to solve coupled PDE's without the necessity of explicitly tracking the interface (free boundary) that would be necessary to solve the classical (sharp interface) model. Recent advances in supercomputing and algorithms now enable generation of interesting and valuable results that display most of the fundamental solidification phenomena and processes that are observed experimentally. These include morphological instability, solute trapping, cellular growth, dendritic growth (with anisotropic sidebranching, tip splitting, and coupling to periodic forcing), coarsening, recalescence, eutectic growth, faceting, and texture development. This talk will focus on the fundamental basis of the phase field model in terms of irreversible thermodynamics as well as it computational limitations and prognosis for future improvement. This work is supported by the National Science Foundation under grant DMR 9211276

• Bulletin of the Korean Chemical Society
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• 제26권7호
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• pp.1057-1064
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• 2005

Photoluminescence (PL) spectra of Eu(III) and Tb(III) complexes with mixed oxydiacetate (ODA) and 1,10-phenanthroline (phen) ligands and with homoleptic ODA reveal characteristic line-splitting at 10 K, depending on the site-symmetry of the lanthanide ion in the complex. The energy-level schemes of the $^7F_J$ states and the emitting levels for Eu(III) and Tb(III) ions have been proposed by simulating the line splitting in the framework of crystal-field Hamiltonian. The sets of refined crystal-field parameters for the experimentally determined sitesymmetry satisfactorily reproduce the experimental energy-level schemes. In addition, the PL quantum yield and the decay time were determined at room temperature. The PL quantum yields of [$Eu(ODA){\cdot}(phen){\cdot}4H_2O]^+$ and [Tb$(ODA){\cdot}(phen){\cdot}4H_2O]^+$ in the crystalline state (Q = 17.7 and Q = 56.6%, respectively) are much greater than those of [Eu($ODA)_3]^{3-}and\;[Tb(ODA)_3]^{3-}$(Q = 1.1 and Q = 1.3, respectively), due to the energy transfer from phen to the lanthanide ion. In the aqueous state, the relaxation of the phen moiety due to the solvent results in the reduction of the quantum yield and the shortening of the lifetime.

• Bulletin of the Korean Chemical Society
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• 제4권2호
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• pp.64-67
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• 1983

NMR shift arising from the electron orbital angular momentum and the electron spin dipolar-nuclear spin angular momentum interactions has been investigated for a $4d^{1}$ system in a strong crystal field of octahedral symmetry. To examine the NMR shif for a $4d^{1}$ system in a strong crystal field of octahedral symmetry, we derive a general expression for ${\Delta}$B/B using a nonmultipole expansion technique. From this expression all the multipolar terms are determined. For the $4d^{1}$ system in a strong crystal field of octahedral symmetry the exact solution for NMR shift, ${\Delta}$B, is compared with the multipolar results. ${\Delta}$B/B for the $4d^{1}$ system is also compared with that for the $3d^{1}$ system. It is found that the $1/R^{7}$ term contributes dominantly to the NMR shift. However, there is good agreement between the nonmultipole and multipolar results for R-values larger than 0.2 nm for the $4d^{1}$ system but for R-values larger than 0.4 nm for the $3d^{1}$ system.

• 한국결정성장학회지
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• 제14권6호
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• pp.244-252
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• 2004

$CuISe_2$ 단결정 박막은 수평 전기로에서 합성한 $CuInSe_2$ 다결정을 증발원으로하여, hot wall epitaxy(HWE) 방법으로 증발원과 기판(반절연성-GaAs(100))의 온도를 각각 $620^{\circ}C$, $410^{\circ}C$로 고정하여 단결정 박막을 성장하였다. 이때 단결정 박막의 결정성은 광발광 스펙트럼과 이중결정 선 요동곡선(DCRC) 으로 부터 구하였다. Hall 효과는 van der Pauw 방법에 의해 측정되었으며, 293K에서 운반자 농도와 이동도는 각각 $9.62\times10^{16}/\textrm{cm}^3$, 296 $\textrm{cm}^2$/Vㆍs 였다. $CuAlSe_2$/Si(Semi-Insulated) GaAs(100) 단결정 박막의 광흡수와 광전류 spectra를 293k에서 10K까지 측정하였다. 광흡수 스펙트럼으로부터 band gap $E_g$(T)는 Varshni 공식에 따라 계산한 결과 1.1851 eV-($8.99\times10^{-4} eV/K)T^2$/(T+153k)였다. 광전류 스펙트럼으로 부터 Hamilton matrix(Hopfield quasicubic mode)법으로 계산한 결과 crystal field splitting Δcr값이 0.0087eV이며 spin-orbit Δso값은 0.2329 eV임을 확인하였다. 10K일 때 광전류 봉우리들은 n = 1일때 $A_1-, B_1$-와 $C_1$-exciton봉우리임을 알았다.

• Corrosion Science and Technology
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• 제22권1호
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• pp.36-43
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• 2023

Single-crystal Ni-rich NCM is a material that has drawn attention in the field of lithium-ion batteries due to its high energy density and long cycle life. In this study, we investigated the properties of single-crystal NCM 811 and its potential for use in lithium-ion batteries. High-quality single crystals of NCM 811 were successfully synthesized by crystal growth via a flux method. The single-crystal nature of the samples was confirmed through detailed characterization techniques, such as scanning electron microscopy and x-ray diffraction with Rietveld refinement. The crystal structure and electrochemical performances of the single-crystal NCM 811 were analyzed and compared to its poly-crystal counterpart. The results indicated that single-crystal NCM 811 had electrochemical performance and thermal stability superior to poly-crystalline NCM 811, making it a suitable candidate for high-performance batteries. The findings of this study contribute to a better understanding of the characteristics and potential of single-crystal NCM 811 for lithium-ion batteries.

• 한국결정성장학회:학술대회논문집
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• 한국결정성장학회 1997년도 Proceedings of the 12th KACG Technical Meeting and the 4th Korea-Japan EMGS (Electronic Materials Growth Symposium)
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• pp.219-222
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• 1997

The principle of dark field imaging is comprehensively discussed using real images of dislocations, stacking faults and gettering phenomena due to defects obtained by Cz Si wafers and LEC semi-insulating GaAs crystals. Resulution of dark field imaging is improved by Fourier transformation of Fraunhofer diffraction pattern obtained at an out-of focusing position of an objective lens.

• Bulletin of the Korean Chemical Society
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• 제16권10호
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• pp.944-952
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• 1995

A generic force field approach has been applied to geometry optimization of penam and cephem crystals. The crystalline state energy and force evaluation with the universal force field (MMFF: Merck Molecular Force Field) results in good agreements with the crystallographic data. Bond lengths are usually correct to within 0.02 Å and bond angles usually to within 2.5°. The conformation of the β-lactam bicyclic rings in the crystal environment is also well reproduced. The results thus demonstrate the applicability of MMFF to modeling of newer molecular constructs in condensed phase.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2005년도 추계학술대회 논문집 Vol.18
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• pp.279-280
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• 2005

We have designed a single gap transflective liquid crystal display (LCD) driven by a fringe electric field and vertical field. The conventional FFS mode does not have an electrode on top substrate, it shows not only slow response time due to weak electric field but also slow discharging problem when electrostatic field is generated after fabricating the cell. To solve these problems, transflective LCD with ITO coated upper substrate was suggested but the transmittance was reduced significantly due to effects from vertical field. Hence, in the present paper, new transflective LCD with ITO coating only in the reflective region was characterized.