• Transactions on Electrical and Electronic Materials
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• v.10 no.1
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• pp.16-19
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• 2009

We have studied the liquid crystal alignment properties for various alignment methods on the homogeneous polyimide surface. Suitable liquid crystal alignment for one-side alignment cell on the polyimide surface by all alignment method was observed. Highly pre-tilt angle of the NLC for both-side rubbing cell was measured. But, low pre-tilt angle of the NLC for one-side ion beam and UV irradiation cell was observed. We consider that the pre-tilt angle of NLC for one-side ion beam and UV irradiation on the PI surface is lower than that of the PI surface with rubbing. Also, the suitable transmittance-voltage curves for the one-side rubbing TN-LCD on the PI surface with one-side UV irradiation were measured. Also, good response time characteristics of the one-side rubbing TN-LCD on the polyimide surface with one-side UV irradiation can be measured.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.17 no.5
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• pp.536-540
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• 2004

A novel nematic liquid crystal (LC) cell with splay structure exhibiting wide viewing angle, fast response time and high transmittance at the same time has been developed. With rubbed homeotropic alignment in parallel directions, the device shows bend alignment in the absence of vertical electric field. However, with applied high voltage in a pulse form, the LC shows a optically compensated splay (OCS) orientation such that the mid-director is parallel to a substrate and at both surfaces the LCs are aligned vertically in parallel direction. In the device, the birefringence of the cell becomes tunable with applying voltage, i.e., the amount of light passed through the cell can be controlled by controlling the orientation of the LC. Since the OCS cell has a self-compensation structure such that the LC has a mirror symmetry along the mid-director, the device shows a wide viewing angle with only a single domain and a fast response time.

• Polymer(Korea)
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• v.26 no.4
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• pp.431-438
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• 2002

We studied the orientation behavior and thermal stability of polyimide (PI) molecules under irradiation of polarized UV (PUV) using polarized fourier transform infrared (FTIR) spectroscopy. In the case of PUV-exposed PI films, the remaining PI molecules after photo-degradation showed molecular orientation perpendicular to the irradiated PUV polarization direction predominantly, due to the preferential degradation of PI molecules parallel to the irradiated PUV Polarization direction. On the other hand, the rubbing of PI films induced reorientation of the PI molecules parallel to the rubbing direction. We also investigated the thermal stability of the alignment layers furled by rubbing and PUV irradiation on the PI films using Polarized FTIR. The thermal stability of the PUV irradiated PI alignment layer is lower than that of the rubbed PI layer due to the fragmentation reaction of the PI by PUV.

• Journal of the Korean Ceramic Society
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• v.36 no.5
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• pp.483-489
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• 1999

Gas pressure sintered silicon nitride based composites with 3 wt% $\beta$-Si3N4 whiskers were prepared and change of properties according to the whisker orientation and sintering temperature was studied. The tapes with whiskers were fabricated by two different method ; conventional tape casting and a modified tape casting by using guide pins,. Orientations of the whiskers were controlled by different stacking sequences of the sheets cut from the tape. Samples were fully densified by gas pressure sintering at 2148-2273K. As the sintering temperature increased size of the large elongated grains increased. In case of unidirectional samples sintering shrinkage normal to the whisker alignment direction was larger than that of parallel to the direction and the shrinkage anisotropy increased slightly as sintering temperature increased. As sintering temperature increased the crack length parallel to whisker alignment direction became shorter but that normal to the direction did not depend on sintering temperature. In case of cross-plied samples the anisotropy of mechanical properties disappeared.

• Smart Structures and Systems
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• v.29 no.2
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• pp.287-299
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• 2022

Rather than using smartphones as seismometers with designated locations and orientations, this study proposes to employ crowds' smartphones in buildings to perform fast safety assessment of buildings. The principal advantage of using crowds' smartphones is the potential to monitor the safety of millions of buildings without hardware costs, installation labor, and long-term maintenance. This study's goal is to measure the maximum interstory drift ratios during earthquake excitation using crowds' smartphones. Beacons inside the building are required to provide the location and relevant building information for the smartphones via Bluetooth. Wi-Fi Direct is employed between nearby smartphones to conduct peer-to-peer time synchronization and exchange the acceleration data measured. An algorithm to align the orientation between nearby smartphones is proposed, and the performance of the orientation alignment, interstory drift measurement, and damage level estimation are studied numerically. Finally, the proposed approach's performance is verified using large-scale shaking table tests of a scaled steel building. The results presented in this study illustrate the potential to use crowds' smartphones with the proposed approach to record building motions during earthquakes and use those data to estimate buildings' safety based on the interstory drift ratios measured.

• Journal of Information Display
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• v.7 no.2
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• pp.12-15
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• 2006

We propose a patterning method of liquid crystal (LC) alignment layer for producing multi-domain LC structures. By controlling thermal conditions during micro-contact printing procedures and facilitating wetting properties of patterning materials, patterned LC orientation can be easily obtained on a bare ITO surface or other polymer films. The newly proposed patterning method is expected to be a very useful tool for fabricating multi-domain LC structures to enhance or design electro-optic properties of LC-based devices.

• Proceedings of the Korean Society of Surveying, Geodesy, Photogrammetry, and Cartography Conference
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• 2004.11a
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• pp.257-262
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• 2004

The purpose of data fusion is collecting maximized information from combining the data attained from more than two same or different kind sensor systems. Data fusion of same kind sensor systems like optical imagery has been on focus, but recently, LIDAR emerged as a new technology for capturing rapidally data on physical surfaces and the high accuray results derived from the LIDAR data. Considering the nature of aerial imagery and LIDAR data, it is clear that the two systems provide complementary information. Data fusion is consisted of two steps, alignment and matching. However, the complementary information can only be fully utilized after sucessful alignment of the aerial imagery and lidar data. In this research, deal with centroid of building extracted from lidar data as control information for estimating exterior orientation parameters of aerial imagery relative to the LIDAR reference frame.

• 한국정보디스플레이학회:학술대회논문집
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• 2005.07a
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• pp.450-452
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• 2005

The ion beam alignment technique is one of the potential and fascinating methods. However, there are merely a few reports about aligning nematic liquid crystals (NLCs) horizontally for in-plane switching mode (IPS) by means of low energy ion beam exposure on inorganic materials such as DLC. In this study, we have investigated the tilted vertical alignment of NLC by the ion beam technique on the thin films of various amorphous silicon compounds as new inorganic alignment materials. Appropriate pretilt angles of NLC with preferred orientation on these thin films were achieved. And the electro-optic property of vertically aligned single domain cells has been investigated.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.32 no.5
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• pp.357-360
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• 2019

We demonstrate an alignment technology using an imprinting process on an inorganic NiOx film. The aligned nanopattern was fabricated on a silicon wafer by laser interference lithography. The aligned nano pattern was then imprinted onto the sol-gel driven NiOx film using an imprinting process at an annealing temperature of $150^{\circ}C$. After the imprinting process, parallel grooves had been formed on the NiOx film. Atomic force microscopy and water contact angle measurements were performed to confirm the parallel groove on the NiOx film. The grooves caused liquid crystal alignment through geometric restriction, similar to grooves formed by the rubbing process on polyimide. The liquid crystal cell exhibited a pretilt angle of $0.2^{\circ}$, which demonstrated homogeneous alignment.

• Proceedings of the Korean Vacuum Society Conference
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• 2014.02a
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• pp.114.2-114.2
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• 2014

The orientation of the constituent molecules in organic thin film devices can affect significantly their performance due to the highly anisotropic nature of ${\pi}$-conjugated molecules. We report here an angle dependent x-ray absorption study of the control of such molecular orientation using well-ordered interlayers for the case of a bilayer heterojunction of chloroaluminum phthalocyanine (ClAlPc) and C60. Furthermore, the orientation-dependent energy level alignment of the same bilayer heterojunction has been measured in detail using synchrotron radiation-excited photoelectron spectroscopy. Regardless of the orientation of the organic interlayer, we find that the subsequent ClAlPc tilt angle improves the ${\pi}-{\pi}$ interaction at the interface, thus leading to an improved short-circuit current in photovoltaic devices based on ClAlPc/C60. The use of the interlayers does not change the effective band gap at the ClAlPc/C60 heterointerface, resulting in no change in open-circuit voltage.