• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.17 no.5
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• pp.526-529
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• 2004

The nematic liquid crysta](NLC) aligning capabilities using a-C:H thin film deposited at the three kinds of rf bias condition were investigated. A high pretilt angle of NLC on low substrate rf bias applied a-C:H thin films was observed and the low pretilt angle of the NLC on high substrate rf bias applied a-C:H thin films was observed. Consequently, the high NLC pretilt angle and the good aligning capabilities of LC alignment by the IB alignment method on the a-C:H thin film deposited at 1 W rf bias condition can be achieved. It is considered that pretilt angle of the NLC may be attributed to substrate rf bias condition and IB energy time. Therefore, LC alignment is affected by topographical structure forming strong IB energy.

• Transactions of The Korea Fluid Power Systems Society
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• v.8 no.3
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• pp.14-20
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• 2011

This study aims at aligning multiple wafers to reduce wafer handling time in wafer processes. We designed a multilevel structure for a prealigner which can handle multiple wafer simultaneously in a system. The system consists of gripping parts, kinematic parts, vacuum chucks, pneumatic units, hall sensors and a DSP controller. Aligning procedure has two steps: mechanical gripping and notch finding. In the first step, a wafer is aligned in XY directions using 4-point mechanical contact. The rotational error can be found by detecting a signal in a notch using hall sensors. A dual prealigner was designed for 300mm wafers and constructed for a performance test. The accuracy was monitored by checking the movement of a notch in a machine vision. The result shows that the dual prealigner has enough performance as commercial products.

• Journal of Biosystems Engineering
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• v.16 no.1
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• pp.9-17
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• 1991

A dynamometer was designed and constructed to measure three directional forces and moments of pull type implement with eliminating the interference between the forces. The dynamometer consists of a linear motion bearing, self-aligning bearings, universal joints, and cantilevers where strain gages were attached. A data acuquisition system was developed to collect data and to analyze them. The data acuquisition system consists of the dynamometer, a potentiometer to measure the implement depth, strain amplifiers, a A/D converter, and an IBM-AT compatible microcomputer. Program, written in C language, was developed to read data from tranducers with given interval, to calculate forces and moments, to display them on screen, and to store them on disk. The calibration results showed that cantilevers had good linearity and there was no interference among directional forces. When applied loads were reduced with constant rate, hysteresis was appeared on the dynamometer. It might to be reduced by using ball bearings instead of self-aligning bearings.

• 한국정보디스플레이학회:학술대회논문집
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• 2005.07a
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• pp.764-767
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• 2005

Photoaligning polymers usually possess "sofe" surface, containing flexible groups and provide relatively small anchoring energy($W<10^{-2}$ erg $cm^{-2}$). In this case field-induced reorientation of director on the aligning surface is essential. We have shown that surface director reorientation can modify the aligning surface and result in gliding of the axis of easy orientation of LC. this phenomena together with adsorption/desorption of ions in electric field cause strong sticking effect in LCDs photoaligning materials. We proposed a method of decreasing of the sticking effect based on irradiation of the photoaligning surface by an unpolarized light.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.16 no.11
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• pp.1014-1018
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• 2003

A photoalignment material of a PGMAcr, poly[3-(acryloyloxy)-2-hydroxypropyl methacrylate] using a photopolymerized the acrylate unit by photo-initiator and a PGMA4Ch, poly[3(4-chalconyloxy)-2-hydroxypropyl methacrylate] using a photodimerization by chalcone group were synthesized. Also, the liquid crystal (LC) aligning capabilities on the photopolymer layers were studied. A good LC alignment with UV exposure on the PGMAcr surface can be obtained. However, the LC alignment defects were observed on the PGMA4Ch surface. The LC aligning capabilities of the PGMAcr surface by photo-initiator were better than that of the PGMA4Ch surface by chalcone group as photosensitive moiety.

• Korean Journal of Optics and Photonics
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• v.8 no.6
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• pp.456-460
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• 1997

Several methods of aligning ring type cavities have been investigated for long time. The measurement of cavity transmission spectrum control is somewhat effective due to aligning cavity with measuring cavity loss at the same time. In this research, four mirrors are aligned and attached by the measurement of pulse width of the transmitted light. The intracavity loss is optimized to about 0.98%, giving the calculated total reflection coefficient of about 99.02%.

• The Transactions of the Korean Institute of Electrical Engineers C
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• v.49 no.11
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• pp.635-639
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• 2000

In this paper, a new idea about ultra-clean aligning and mounting method of FED spacers was introduced. The glass-to -glass electrostatic bonding process was employed in order to bond the micro-structures of spacers to black matrix area formed on an FED anode substrate. It is possible to get adhesive-free bonding interface and well-aligned spacer array on an FED anode substrate with a ${\pm}5{\mu}m$ accuracy. Finally, I inch-sized FED panel was demonstrated to make sure of its applicability to FED panel fabrication.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2000.11a
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• pp.141-144
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• 2000

New photo-alignment materials based on PCEMA (Poly (4-methacryloyloxylchalcone)) for liquid crystal (LC) aligning were synthesized. And the electro-optical (EO) characteristics of the photo-aligned TN-LCD were investigated. The excellent LC alignment and voltage-transmittance (V-T) characteristics for the photo-aligned TN-LCD on PCEMA surface containing more cinnamoly group can be achieved. However, the reverse tilt disclinations for the photo-aligned TN-LCD on the PCEMA surface containing more OH group were observed. Consequently, we suggest that the LC aligning capabilities can be increased by increasing of cinnamoly group on the PCEMA surfaces.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.13 no.3
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• pp.235-240
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• 2000

New photh-alignment materials based on PCEMA (poly(4-methacryloyloxylchalcone))for liquid crystal (LC) aligning were synthesized. and the electro(EO) characteristics of the photo-aligned TN-LCD were investigated. The excellent LC alignment and voltage-transmittance (V-T) characteristics for the photo-aligned TN-LCD on PCEMA surface containing more cinnamoly group can be achieved. However the reverse tilt disclinations for the photo-aligned TN-LCD on the PCEMA surface containing more OH group were observed. Consequently we suggest that the LC aligning capabilities can be increased by increasing of cinnamoly group on the PCEMA surfaces.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.14 no.11
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• pp.917-921
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• 2001

Aligning capabilities for nematic liquid crystal (NLC) using a in-situ photodimerization method on various Photo-crosslinkable Polyimide (Pl) based polymer and blending photopolymer surfaces were investigated. High pretilt angle of the NLC can be measured by obliquely polarized UV exposure on a photo-crosslinkable polyimide based polymer surface containing biphenyl (BP), decyl (de), and cholesteryl (chol) group, respectively. However, the low pretilt angle of the NLC was measured by obliquely polarized UV exposure on the blending photopolymer (Pl and cinnamate materials) surfaces. Consequently, the pretilt angle of the NLC generated on the photo-crosslinkable polyimide based polymer surfaces using the in-situ photodimerization method was higher than that of the blending photopolymers.