Byungchoon Yang

Activation of Vanilloid Receptor 1 (VR1) by Eugenol

The structural similarity of eugenol with capsaicin suggests that these two agents may share molecular mechanisms to produce their effects. We investigated the effects of eugenol in comparison with those of capsaicin using whole-cell patch clamp and Fura-2-based calcium-imaging techniques in a heterologous expression system and with sensory neurons. In vanilloid receptor 1 (VR1)-expressing human embryonic kidney (HEK) 293 cells and trigeminal ganglion (TG) neurons, eugenol activated inward currents, whereas capsazepine, a competitive VR antagonist, and ruthenium red (RR), a functional VR antagonist, completely blocked eugenol-induced inward currents. Moreover, eugenol caused elevation of [Ca2+]i, and this was completely abolished by both capsazepine and ruthenium red in VR1-expressing HEK 293 cells and TG neurons. Our results provide strong evidence that eugenol produces its effects, at least in part, via VR1 expressed by the sensory nerve endings in the teeth.

Electrically controllable long-period liquid crystal fiber gratings

An electrically controllable fiber-optic filter for broad-band rejection has been demonstrated by periodically poling a liquid-crystalline core in a hollow-core fiber by means of an external long-period-combed electrode. The periodically poled liquid-crystalline core in a period of 483 /spl mu/m couples the fundamental core mode to the leaky cladding modes. A maximum loss dip of approximately 15-nm bandwidth and 6 dB band rejection has been obtained for a nonpolarized light with a combed 250-V external voltage modulation. The experimental result matches well with a numerical expectation, which has been analyzed by the discretized coupled-mode theory for an anisotropic perturbation.

A Novel Two-Dimensional Adaptive Dimming Technique of X-Y Channel Drivers for LED Backlight System in LCD TVs

In this paper, a novel two-dimensional (2-D) adaptive dimming technique with X-Y channels for light-emitting diode (LED) backlight system in LCD TVs is proposed. The proposed LED backlight has matrix-structured LED modules with row and column switches to control the brightness of individual division block. It shows local dimming effects such as reduced power consumption and high dynamic contrast ratio even with much less number of LED drivers than that of the conventional 2-D local dimming method. Therefore, low cost and compact design of LED drivers can be achieved. This paper also contains a new adaptive dimming algorithm and image manipulation technique for the proposed LED backlight system. The proposed dimming technique is verified by simulation and experimental results based on a RGB-LED backlight of a 32-in LCD TV.

Iterative Fourier transform algorithm with regularization for the optimal design of diffractive optical elements.

There is a trade-off between uniformity and diffraction efficiency in the design of diffractive optical elements. It is caused by the inherent ill-posedness of the design problem itself. For the optimal design, the optimum trade-off needs to be obtained. The trade-off between uniformity and diffraction efficiency in the design of diffractive optical elements is theoretically investigated based on the Tikhonov regularization theory. A novel scheme of an iterative Fourier transform algorithm with regularization to obtain the optimum trade-off is proposed.

64.4: Smart Algorithms for Local Dimming LED Backlight

To reduce power consumption and improve image quality including contrast ratio and color gamut, LED backlight units (BLUs) consisting of many small blocks in 2-dimensional space are implemented. Either white-gray-level luminance or color is controlled by the local dimming LED BLU. However, such a BLU can induce various recognizable artifacts. A method is proposed for exact block luminance calculation along with a new algorithm to correct local dimming artifacts. A new concept of color classes has also been developed to achieve extremely wide color gamut and to minimize color related artifacts.

A novel adaptive dimming technique with X-Y channels for LED backlight system of LCD TVs

A novel adaptive dimming technique with X-Y channels for light emitting diode (LED) backlight system of LCD TVs is proposed. It has matrix structured LED modules with row and column switches to control the brightness of individual division block. It shows local dimming effects such as reduced power consumption and high dynamic contrast ratio with even using much fewer number of LED drivers of proposed method than that of conventional local dimming method. Therefore, low cost and compact design of LED drivers can be achieved. This paper also contains a new adaptive dimming algorithm and image compensation technique for proposed system.

A Generalized Fabry–Pérot Formulation for Optical Modeling of Organic Light-Emitting Diodes Considering the Dipole Orientation and Light Polarization

The Fabry-Pérot formulation has been widely used as a simple and intuitive optical modeling method of organic light-emitting diodes (OLEDs). However, because the Fabry-Pérot formulation in the optical modeling of OLEDs does not include the effect of the dipole orientation and light polarization on light emission characteristics, rigorous electromagnetic models should be used, in spite of their heavy mathematical and computational complexity. In addition, the validity and the limitation of the Fabry-Pérot formulation for OLEDs have yet to be proven. We propose a generalized Fabry-Pérot formulation to calculate the dependence of the dipole orientation and light polarization on the angular emission characteristics using a simple analytical equation rather than a complicated electromagnetic model. The generalized Fabry-Pérot formulation is derived, together with detailed steps, and becomes equivalent to the current Fabry-Pérot formulation in isotropic dipole orientation. In addition, the physical interpretation of the proposed Fabry-Pérot formulation is elucidated in comparison with the quantum mechanical model. To demonstrate the applicability and the validity of the generalized Fabry-Pérot formulation, the angular emission spectra of a top-emitting OLED are calculated with respect to the horizontal dipole ratio and the light polarization, which can be easily calculated based on a simple analytical equation.

Geometrical analysis of optical transmission characteristics of prism sheet layers

We analyze the optical transmission characteristics of prism sheet layers based on a geometrical approach. An analytic method for finding the radiant intensity profile of the light transmitted through a single prism sheet for an incident light with arbitrary radiant intensity profile is developed. It is shown that the output radiant intensity profile is the inner product of the newly defined partial transmission coefficient distribution of the prism sheet and the input radiant intensity profile. The developed analysis method for a single prism sheet is immediately generalized to analyze prism sheet layer being composed of several prism sheets.

Effect of the finite pixel boundary on the angular emission characteristics of top-emitting organic light-emitting diodes

We numerically investigate the effect of the pixel boundary on the angular emission characteristics of top-emitting organic light-emitting diodes (OLEDs) using the finite element method. A three-dimensional OLED structure has the square pixel boundary, which is surrounded by the pixel definition layer. The angular emission characteristics based on the Poynting vectors are calculated in various positions of a Hertz dipole emitter within the pixel boundary. When the dipole emitter is located near the center of the square pixel, the angular emission characteristics have a symmetric forward-directed pattern, which is similar to the angular emission pattern calculated by the thin-film-based optical model. When the position of the dipole emitter is close to the pixel boundary, the angular emission pattern becomes asymmetric because the optical reflections from the pixel boundary in the horizontal direction affect the emission pattern of the dipole emitter. The total angular emission characteristics of the top-emitting OLED are obtained by summing the individual angular emission pattern of the whole dipole emitters, which are assumed to be uniformly distributed in the two-dimensional emission plane. The asymmetrical angular emission characteristics of the dipole emitters near the pixel boundary contribute to narrowing the total angular emission pattern.

Soft Decision Decoding for Holographic Memories with Intrapage Intensity Variations

A holographic memory system using a two-dimensional array of code sequences and soft decision decoding is implemented. The random error correction and burst error correction capability of this system is shown. We can obtain lower bit error rates using soft decision Viterbi decoding rather than using hard decision decoding or simple thresholding. Different threshold levels for each data pixel position are determined by considering intrapage intensity variations. With these threshold levels, much lower bit error rates are obtained. The experimental results are presented.