• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.16 no.10
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• pp.914-922
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• 2003

The FFS (fringe-field switching) mode was known to exhibit both a wide viewing angle and high transmittance, especially when using a liquid crystal with negative dielectric anisotropy. We have studied cell gap-dependent electrode-optic characteristics of the FFS mode using the LC with negative dielectric anisotropy. In case of a small cell gap of 2 ${\mu}$m, the transmittance at the center of pixel and common electrodes is relatively low because effect of surface anchoring that holds the LC to the initial state is larger than that in a large cell gap of 4 .urn such that the LCs in those regions cannot rotate enough. However, in case of a large cell gap of 4 .urn, the effect of surface anchoring becomes relatively small so that the LCs at the center of pixel and common electrode can be twisted enough by applied voltage, giving rise to high transmittance. Therefore, we can conclude that the light efficiency is dependent on the cell gap.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.14 no.10
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• pp.945-954
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• 2004

Recently, specifications of flat display module is going to be higher definition, brightness and more wide viewing angle. On the other hand, physical thickness of those modules is forced to be slimmer and lighter. The flat display modules such as plasma or TFT-LCD employ thin crystallized panels that are normally weak to high level transient mechanical energy inputs. As a result, anti-shock performance is one of the most important design specifications of TFT-LCD modules. TFT-LCD module manufacturers and their customers like PC or TV makers perform a series of strict impact/drop test for the modules. However most of the large display module designs are generated based on engineer's own trial-error experiences. Those designs may result in disqualification from the drop/impact test during final product evaluation. A rigorous study on the impact failure of the displays is of course necessitated in order to avoid the problems. In this article, a systematic design evaluation is presented with combinations of FEM modeling and testing to support the optimal shock proof display design procedure.

• Journal of Astronomy and Space Sciences
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• v.30 no.2
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• pp.91-94
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• 2013

We use the outer gap model to explain the spectrum and the energy dependent light curves of the X-ray and soft ${\gamma}$-ray radiations of the spin-down powered pulsar PSR B1509-58. In the outer gap model, most pairs inside the gap are created around the null charge surface and the gap's electric field separates the opposite charges to move in opposite directions. Consequently, the region from the null charge surface to the light cylinder is dominated by the outflow current and that from the null charge surface to the star is dominated by the inflow current. We suggest that the viewing angle of PSR B1509-58 only receives the inflow radiation. The incoming curvature photons are converted to pairs by the strong magnetic field of the star. The X-rays and soft ${\gamma}$-rays of PSR B1509-58 result from the synchrotron radiation of these pairs. The magnetic pair creation requires a large pitch angle, which makes the pulse profile of the synchrotron radiation distinct from that of the curvature radiation. We carefully trace the pulse profiles of the synchrotron radiation with different pitch angles. We find that the differences between the light curves of different energy bands are due to the different pitch angles of the secondary pairs, and the second peak appearing at E > 10 MeV comes from the region near the star, where the stronger magnetic field allows the pair creation to happen with a smaller pitch angle.

• Journal of Broadcast Engineering
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• v.25 no.6
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• pp.836-844
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• 2020

A very large number of pixels is required to generate a computer generated hologram (CGH) with a large-size and wide viewing angle equivalent to that of an analog hologram, which incurs a very large amount of computation. For this reason, a high-performance computing device and long computation time were required to generate high-definition CGH. To solve these problems, in this paper, we propose a technique for generating high-definition CGH by arraying the pre-calculated low-definition CGH and multiplying the appropriately-shifted concave lens function. Using the proposed technique, 0.1 Gigapixel CGH recorded by the point cloud method can be used to calculate 2.5 Gigapixels CGH at a very high speed, and the recorded hologram image was successfully reconstructed through the experiment.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.19 no.4
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• pp.362-366
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• 2006

OLEDs(Organic Light Emitting Diodes) are attractive as alternative display components because of their relative merits of being self-emitting, having large intrinsic viewing angle and fast switching speed. But because of their relatively short history of development, much remains to be studied in terms of their basic device physics and design, manufacturing techniques, stability and so on. We investigated electrical properties of N, N-diphenyl-N, N bis (3-methyphenyl-l,1'-biphenyl-4,4'-diamine (TPD) and tris-8-hydroxyquinoline aluminum$(Alq_3)$ when their thicknesses were changed variedly from 3:7 to 5:5 of their thickness ratios. And we also studied properties of OLED depend on their deposition rate between $0.05{\sim}0.2$ nm/s.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2010.06a
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• pp.270-270
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• 2010

OLED device is one of the most attractive and alternative display components, which stems primarily from the self-emission, large intrinsic viewing angle, and fast switching speed. However, because of its relatively short history of development, much remains to be studied in terms of its basic device physics, manufacturing processes, and reliability etc. Especially among several issues, it should be noted that the device characteristics are very sensitive to the surface properties of transparent conducting oxide (TCO) electrode materials. In this study, we have investigated the performance of OLED devices as a function of sheet resistance and surface roughness of TCO thin films. For this purpose, ITO and IZO thin films were deposited by r. f. magnetron sputtering under various ambient gases (Ar, Ar+O2 and Ar+H2, respectively). The crystal structure and surface morphology were examined by using XRD and FESEM. Also, electrical and optical properties were Investigated.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.10 no.5
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• pp.905-909
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• 2006

Recently various types of curved integral imaging system have been reported for improvement of viewing angle. However, the optical implementation has been limited to only unidirectional system. In this paper, we propose a curved integral imaging (CII) system with additional use of a large-aperture ten in conventional II system and explain a generation scheme of elemental images in the proposed system. The proposed system provides full-directional curvature effect and has simple structure due to the use of well-fabricated flat devices. For the full-directional-curved II system, we perform my analysis based on Johns matrix and synthesize novel elemental images. To show the usefulness of synthesized elemental images, preliminary experiments were performed and some experimental results were presented.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2005.11a
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• pp.275-276
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• 2005

Organic Light Emitting Diodes(OLEDs) are attractive as alternative display components because of their relative merits of being self-emitting, having large intrinsic viewing angle and fast switching speed. But because of their relatively short history of development, much remains to be studied in terms of their basic device physics and design, manufacturing techniques, stability and so on. We invested electrical properties of N,N-diphenyl-N,N bis (3-methyphenyl)-1,1'-biphenyl-4,4'-diamine(TPD) and tris-8-hydroxyquinoline aluminum($Alq_3$) when their thicknesses were changed variedly from 3:7 to 7:3 of their thickness ratios. And we also studied properties of OLEDs depend on their deposition rate between 0.05$\sim$0.2 [nm/s].

• The Bulletin of The Korean Astronomical Society
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• v.38 no.1
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• pp.31.1-31.1
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• 2013

Barred-spiral galaxies possess double patterns: a bar and spiral arms. While their angular speeds play an important role in governing gas dynamical evolution of barred spiral galaxies, there is no direct way to observe them. The Tremaine-Weinberg (TW) method has been one of the most reliable indirect methods to estimate pattern speeds, although it requires a few strict assumptions, notably one that the gas tracer is in a quasi-steady state. In barred-spiral galaxies, however, non-steady gas flows are significant especially when the double patterns have different angular speeds. Using numerical models, we explore the effect of non-steady gas motions on the determination of double pattern speeds based on the TW method. We find that the TW method is accurate within 15% when there is only a single pattern or when double patterns have the same angular speed. When double patterns have different speeds, on the other hand, neglecting the non-steady flows leads to quite large errors (> 30%) in the derived pattern speeds, and severely underestimate the real values for the viewing angle parallel to the bar minor axis. This suggests that one should be cautious when applying the TW method to galaxies with double patterns with different speeds.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2005.07a
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• pp.74-75
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• 2005

Organic Light Emitting Diodes are attractive as alternative display components because of their relative merits of being self-emitting, having large intrinsic viewing angle and fast switching speed. But because of their relatively short history of development, much remains to be studied in terms of their basic device physics and design, manufacturing techniques, stability and so on. We invested electrical properties of N, N-diphenyl-N, N bis (3-methyphenyl)-1, 1'-biphenyl-4, 4'-diamine and tris-8-hydroxyquinoline aluminum when their thickness were changed variedly from 3:7 to 7:3 of their thickness ratios. And we also studied their optimal thickness respectively.