• Proceedings of the KIEE Conference
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• 1997.07d
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• pp.1585-1587
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• 1997

We investigated the generation of high pretilt angle for nematic liquid crystal (NLC) in the cell with slanted non-polarized ultraviolet (UV) light irradiation on two kinds of the polyimide (PI) film. It was shown that the monodomain alignment in NLC is obtained in the cell with slanted non-polarized UV light irradiation on PI surface. The pretilt angle of NLC is generated about 3 degrees in the cell with slanted non-polarized UV light irradiation with 70 degrees on PI surface without side chain. But, the pretilt angle of NLC is generated about 1 degree in the cell with slanted non-polarized UV light irradiation with 80 degrees on PI surface with side chain. We consider that the pretilt angle generation in NLC is attributted to anisotropic dispersion force between the LC molecular and the PI surface.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.34 no.1
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• pp.8-15
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• 2021

Micro-LEDs can be applied to various parts of a product. However, it has disadvantages compared to general LEDs in large displays such as low efficiency, intensity, and contrast ratio, among others, owing to their short history of study. The simulations were carried out using ray-tracing software to investigate the change in light intensity and light distribution according to pattern shapes on the sapphire substrate of the flip-chip micro-LED (FC μ-LED) array. Three patterns-concave square patterns, convex square patterns, and Ag coated convex patterns-which existed on the opposite side of FC μ-LEDs (115 ㎛ × 115 ㎛) array, were applied. The intensity of FC μ-LEDs on the center of the receivers depends on the pattern depth with shape. The concave square patterns having FC μ-LEDs arrays show that decreasing intensity as the patterns depth. On the contrary, the convex square patterns having FC μ-LEDs arrays shows that increasing intensity as the patterns depth. In addition, the highest intensity shows that FC μ-LEDs having Ag-coated convex patterns on the opposite side of sapphire lead to a reduction in light crosstalk owing to the Ag film.

• Korean Journal of Occupational Health Nursing
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• v.9 no.2
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• pp.143-154
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• 2000

This study was carried out to introduce the Foot reflexo-massage (FRM) as a method of nursing practice based on the health promotion of occupational health. Literature reviews were done to achieve study aims from October in 1999 to August in 2000. The results were as follow ; 1. Theory of the FRM was mainly developed from the reflexology based on function and role of foot. 2. The FRM is focused on the appropriate reflexology of foot with pressures of light-moderate-light or light-strong-light scaled strength for 15 minutes at each feet. The massage should begin with the foot area where it is assumed as a was, of internal to external and upper to lower side. It also should start from left to light side of the feet. 3. The FRM is an alternative therapy increasingly demanded as an self applying method between eastern and western due to the benefit of natural healing power with no side effects. 4. The FRM can be an nursing intervention for health promotion of employees through supportive and educative nursing system in occupational health service. As a conclusion of the study, it suggested that the FRM can be recommended as a nursing intervention to promote health of employees and to prevent disease related to work.

• Proceedings of the IEEK Conference
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• 2008.06a
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• pp.1117-1118
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• 2008

The LightScribe Technology is for printing images on the label side of recordable media using CD laser diode. By implementing Optimum Labeling Power Calibration for LightScribe, Labeling Quality can be improved. This paper proposes a new laser power calibration method using RFSUM signal. This function is implemented based on GH22LP20 of LG Electronics.

• Proceedings of the KSR Conference
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• 2011.10a
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• pp.2718-2725
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• 2011

The VAL 208 in Uijeongbu Light Rail system is a light railway vehicle which could be operated in driverless supported by Siemens. It is a Rubber Wheel Type AGT (Automatic Guideway Transit). It will be operated in two car train about 11km of Uijeongbu line. In this paper, the technical overview of the ATC system and the interface between the system and the way side control equipments are presented. It includes the main functions of OBCU(On Board control Unit) and its information sharing method with WCU(Way side control Unit). The testing procedure of OBCU is also discussed.

• International Journal of Precision Engineering and Manufacturing
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• v.7 no.2
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• pp.52-55
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• 2006

The OLEDs(Organic Light-Emitting Diodes) structure organizes the bottom layer using glass, ITO(indium thin oxide), hole injection layer, hole transport layer, emitting material layer, electron transport layer, electron injection layer and cathode using metal. OLED has various advantages. OLEDs research has been divided into structural side and emitting material side. The amount of emitting light and luminescence efficiency has been improved by continuing effort for emitting material layer. The emitting light mechanism of OLEDs consists of electrons and holes injected from cathode and anode recombination in emitting material layer. The mobilities of injected electrons and holes are different. The mobility of holes is faster than that of electrons. In order to get high luminescence efficiency by recombine electrons and holes, the balance of their mobility must be set. The more complex thin film structure of OLED becomes, the more understanding about physical phenomenon in each interface is needed. This paper observed what the thickness change of hole transport layer has an affection through the below experiments. Moreover, this paper uses numerical analysis about carrier transport layer thickness change on the basis of these experimental results that agree with simulation results.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.21 no.9
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• pp.859-862
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• 2008

We have realized static image on organic light emitting diodes (OLEDs) using photoluminescence degradation. Ultraviolet (UV) was irradiated to the glass side of device. UV power was 350 Wand the wavelength was 365 nm. The UV irradiation gives rise to the degradation of photoluminescence. Due to the degradation, the current density-voltage curve was shifted to the higher voltage side and the luminescence was also degraded by the current and photoluminescence drop. The negative imaged films were prepared to control the transmittance of UV. The UV light was passed through the film. By this method, the film image was transferred to the device with reversed image and the static image was realized on the OLED.

• Transactions on Electrical and Electronic Materials
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• v.15 no.1
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• pp.45-48
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• 2014

We have investigated the effects of an Ag capping layer on the emission characteristics of transparent organic light-emitting devices with Ca/Ag double-layer cathodes. The thickness of the Ag layer was varied from 10 to 30 nm, whereas the Ca was fixed to be a 10 nm in the Ca/Ag structure. The luminance and current efficiency on the cathode and anode sides are significantly dependent on the Ag thickness. For example, the current efficiency on the anode side increases from 8.4 to 11.7 cd/A, whereas, on the cathode side, it decreases from 3.2 to 0.2 cd/A as the Ag thickness increases from 10 to 30 nm. These changes in emission characteristics were investigated by measuring electroluminescence, transmission, and reflection spectra.

• Bulletin of the Korean Chemical Society
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• v.20 no.9
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• pp.1010-1016
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• 1999

We synthesized the photoresponsive side chain polymers containing aminonitro azobenzene for studying the effect of temperature on photoinduced birefringence. Four different copolymers were prepared using methacrylate, α-methylstyrene, and itaconate monomer. Photoisomerization was observed under the exposure of UV light using UV-VIS absorption spectroscopy. Reorientation of polar azobenzene molecules induced optical anisotropy under a linearly polarized light at 532 nm. The change of the birefringence was observed with increasing the sample temperature under a continuous irradiation of excitation light. We could estimate the activation energy of molecular motion in thermal and photochemical mode. Besides the effect of glass transition temperature on the activation energy, we focused our interests on the effect of geometrical hindrance of polar azobenzene molecules and cooperative motion of environmental mesogenic molecules in the vicinity of polar azobenzene molecules.

• Journal of the Optical Society of Korea
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• v.11 no.3
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• pp.113-117
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• 2007

A LED light coupler is proposed for coupling light from a mini side LED of 0.4 mm height to a very thin (${\sim}0.3 mm$) light guide. Due to the ultra thinness of the light guide, conventional light couplings between LEDs and light guides do not provide adequate coupling efficiency. The designed LED coupler is a compound lens of 3.5 mm length, 1.2 mm height, and 3.3 mm width. The courier first collimates the light from the LED and then concentrates the light in a manner similar to a compound parabolic concentrate, (CPC) into the light guide. The exit surface of the coupler is additionally textured to have micro patterns in order to control the radiance profile.