• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2008.11a
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• pp.310-311
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• 2008

We have studied electro-optical characteristics of fringe-field switching (FFS) mode with high $d{\Delta}n$ according to the electrode position. In this device, the fringe-electric field drives the LCs to rotate so that the dielectric torque is electrode-positional dependent, which results in electrode-position dependency in the LC's rotating angle. We confirmed polarization microscope image and chromaticity diagram at the different electrode position with LC that have high $d{\Delta}n$. Since the FFS mode is influenced by horizontal and vertical electric field, the FFS mode modulates light using both phase retardation and polarization rotation effect, which had already been verified with previous studies. However, from another point of view, tight modulation of FFS mode has been demonstrated by performing experiment and calculated simulation at the high $d{\Delta}n$ LC cell.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2009.04a
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• pp.61-62
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• 2009

Electro-optical properties of liquid crystal display (LCD) using fringe-field switching (FFS) devices depend on many parameters such as cell retardation, electrode structure, magnitude and sign of dielectric anisotropy, rubbing angle and cell gap. In this paper, the light efficiency of FFS device depending on magnitude of positive dielectric anisotropy with other cell parameters such as rubbing angle and angle and cell gap have been explored compared with FFS device using LC with negative dielectric anisotropy.

• Journal of Korean Ophthalmic Optics Society
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• v.6 no.2
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• pp.11-16
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• 2001

The polariscope to measure :he stress in lens was made up quarter-wave plate polarizer and we analyzed two components of light's wave $E_1$ and $E_2$ following the steps. It is clear that the principal-stress difference ${\sigma}_1-{\sigma}_2$ can be determined in 2-D model if fringe order N is measured each point in sample moreover. the optical axes of sample coincide with the principal-stress directions. The birefringence acted to a light wave and a phase retardation were in proportioned to the principal-stressed difference (${\sigma}_1-{\sigma}_2$) and the intensity of final light wave was proportioned to $sin^2({\Delta}/2)$, when ${\Delta}/2=n^{\pi}$ (n=0, 1, 2, ...) and the extinction occurs. As a experimental result, the extinction band shifted owing to a magnitude of lens' external stress.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2003.07b
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• pp.972-975
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• 2003

We have performed computer simulation to obtain electro-optic characteristics of reflective hybrid aligned nematic liquid crystal displays driven by fringe field. The results show that the optimal retardation value of the cell is $0.289{\mu}m$, which allows for the cell to have a practical cell gap of larger than $3{\mu}m$ when manufacturing. A reflectance of the dark state is only 0.114% for an incident light 550nm. At this condition, the light efficiency of white state reaches 92.7%. Further, we have studied a new reflective display with polarizer, optical compensation with half plate, LC plus reflector. The display with optimized cell parameters shows low wavelength dispersion and the contrast ratio greater than 5 over exists about $120^{\circ}$ in vertical direction and $160^{\circ}$ in horizontal direction.

• Transactions of Materials Processing
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• v.8 no.3
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• pp.309-309
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• 1999

Effects of rare earth metals addition and aging treatment on corrosion resistance and mechanical properties of super duplex stainless steels were investigated using optical/SEM/TEM metallographic examination, an X-ray diffraction test, a potentiodynamic anodic polarization test and a tensile test. The performance of the experimental alloy with 0.32% REM addition was compared with commercial super duplex stainless steel such as SAF 2507 when they were exposed to solution annealing heat treatment and aging treatment. The corrosion resistance in CF environments and mechanical properties of the experimental alloy were found superior to those of the commercial duplex stainless steel. The REM with larger atomic radii than those of Cr, Mo and W may fill vacancies inside the matrix and around the grain boundaries, retarding formation of harmful intermetallic σ and χ phases. In addition, fine REM oxides/oxy-sulfides (1-3㎛) seemed to enhance the retardation effects. With REM additions, strength and ductility increased due to the phase and grain refinement caused by fine REM oxides and oxy-sulfides.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2006.06a
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• pp.461-462
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• 2006

A single-gap and single-gamma transflective liquid-crystal (LC) display using patterned vertical alignment (PVA) mode was designed. In the device, a vertical electric field drives a vertically aligned LC to tilt down to optimize polarization efficiency. Electrodes of transmissive and reflective area were patterned $22.5^{\circ}$ and $45^{\circ}$ with respect to the polarizer so that a tilt-down direction of the LC director was $22.5^{\circ}$ and $45^{\circ}$ in the reflective and transmissive regions, respectively. In the device, the cell gap was the same for both regions, and the gamma curve matched each other in both regions because tilt angle of LC director was the same according to the applied voltage. Moreover, the dark state was irrespective of the cell retardation value at normal direction, which was highly important in massive fabrications. The switching principle and electro-optic characteristics of the device are reported herein.

• Journal of the Semiconductor & Display Technology
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• v.22 no.3
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• pp.90-95
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• 2023

We describe an optimal alignment method for improving accuracy of dynamic spectroscopic polarimeter based on monolithic polarizing interferometer. The dynamic spectroscopic polarimeter enables real-time measurements of spectral ellipsometric parameters by using a spectral carrier frequency concept. However, the non-polarizing beam splitter used in the monolithic polarizing interferometer cannot maintain the polarization state perfectly due to phase retardation caused by optical anisotropic characteristics of the non-polarizing beam splitter, resulting in degraded measurement accuracy. The effect of the beam splitter can be minimized through optimal alignment of the polarizers used in the polarizing interferometer and the analyzer. We demonstrate how much the proposed alignment method can enhance the measurement accuracy by comparing with previous alignment approach.

• 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.

• Proceedings of the Polymer Society of Korea Conference
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• 2006.10a
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• pp.239-239
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• 2006

In the present study, we synthesized CBDA-FDA and its analogue, poly(4,4' -(9,9-fluorenyl)diphenylene pyromellitimide) (PMDA-FDA), and then investigated quantitatively the orientational distributions of the polymer chain segments in the surfaces of their films by using linearly polarized Fourier transform infrared (FTIR) spectroscopy and optical retardation analysis. We also examined the films' surface topographies using high spatial resolution atomic force microscopy (AFM). Further, rubbed films were used to assemble antiparallel and $90^{\circ}-twisted$ nematic (TN) LC cells, and the alignment behaviors, pretilt angles and anchoring energies of the LC molecules in the cells were determined. The films were found to have very interesting surface morphologies and LC alignment behaviors, which have not previously been reported. The observed LC alignments, pretilt angles and anchoring energies are discussed by taking into account the interactions of the LC molecules with the oriented polymer chain segments and the surface morphologies.

• Journal of Korean Ophthalmic Optics Society
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• v.10 no.1
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• pp.9-15
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• 2005

The polariscope to measure the microscopic stress in CR lens consists of light source polarizer, model, polarizer, CCD, computer, chrome conversion orderly and the principal-stressed difference, (${\sigma}_1-{\sigma}_2$) and the fringe order n were measured by analyzing two components of light wave $E_1$ and $E_2$ following each polarizer's steps. The two-dimensional model could be determined from the fact that the optical axes of sample concide with the principal-stress directions. The bi-refringence acted to a light wave and the phase retardation were in proportion to the principal-stressed difference(${\sigma}_1-{\sigma}_2$) and the intensity of final light wave was proportioned to $sin2({\Delta}/2)$ and when ${\Delta}/2=n{\pi}$ (n=0, 1, 2, ${\ldots}$) the extinction occurs. Photoelastic's image by microscopic stress could analyzed using chrome conversion, and the image showed clearly.