• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2001.11a
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• pp.108-111
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• 2001

ZnO thin films on (001) sapphire substrates knave been deposited by pulsed laser deposition(PLD) technique for light emitting device applications. We have controlled the emission intensity of UV and visible light, depending on film thickness and various post-annealing time. UV emission became strong as the thickness of ZnO thin films increased. The intensity of visible light was strong as post-annealing temperature increased. The optical properties of the ZnO thin films were characterized by PL(photoluminescence) and the structural properties of the ZnO were characterized by XRD for the application of ZnO light emission device.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.24 no.12
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• pp.38-46
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• 2010

For the development of 100[W] stage lighting, quantitative and uniform color mixing that applied through color adopted Simple-Inverse matching so that color mixing can be possible along Black Body Locus. R,G,B(Red, Green, Blue) LED(Light Emitting Diode) arrangement through LED package character analysis, LED module, and the characteristic of device were considered for uniform color mixing. A distance changeable optical device was built to assure high uniformity and high diffusion of not only the middle of diffusion side but also the border side. Also, we developed the control power circuit that can expand up to 6 channels which are possible for quantitative color mixing, and the high uniformity and high quantified border light for color mixing control and the verification of color mixing characteristics by composing GUI(Graphical user interface) including color mixing simulator. By presenting the experimental results of light color control, we proved the usefulness of our developed border light and the proposed color mixing method.

• Proceedings of the KIEE Conference
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• 2007.04a
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• pp.73-76
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• 2007

Photodynamic diagnosis(PDD) is a method to diagnose the possibility of cancer, both by the principle that if a photosensitizer is injected into an organic tissue, it is accumulated in the tissue of a malignant tumor selectively after a specific period, and by a comparison of the intensity of the fluorescence of normal tissue with abnormal tissue after investigating the excitation light of a tissue with accumulated photosensitizer. Since the selection of the wavelength band of excitation light has an interrelation with fluorescence generation according to the selection of a photosencitizer, it plays an important role in POD. This study aims at designing and evaluating light source devices that can stably generate light with various kinds of wavelengths In order to make possible PDD using a photosensitizer and diagnosis using auto-fluorescence. The light source device was a Xenon lamp and filter wheel, composed of an optical output control through Iris and filters with several wavelength bands It also makes the inducement of auto-fluorescence possible because it is designed to generate a wavelength band of 380-400. The transmission part of the light source was, developed to enhance the efficiency of light transmission. To evaluate this light source device, the characteristics of the light output and wavelength band were verified. To validate the capability of this device as PDD the detection of auto-fluorescence using mouse was performed.

• Journal of the Korean Ceramic Society
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• v.56 no.1
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• pp.98-103
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• 2019

Optical filters to control light wavelength of displays or cameras are fabricated by multi-layer stacking process of low and high index thin films. The process of multi-layer stacking of thin films has received much attention as an optimal process for effective manufacturing in the optical filter industry. However, multi-layer processing has disadvantages of complicated thin film process, and difficulty of precise control of film morphology and material selection, all of which are critical for transmittance and coloring effect on filters. In this study, the composite $TiO_2$, which can be used to control of UV absorption, coated on nano hollow silica sol, was synthesized as a coating material for optical filters. Furthermore, systematic analysis of the process parameters during the chemical reaction, and of the structural properties of the coating solutions was performed using SEM, TEM, XRD and photo spectrometry. From the structural analysis, we found that the 85 nm nano hollow silica with 2.5 nm $TiO_2$ shell formation was successfully synthesized at proper pH control and titanium butoxide content. Photo luminescence characteristics, excited by UV irradiation, show that stable absorption of 350 nm-light, correlated with a 3.54 eV band gap, existed for the $TiO_2$ shell-nano hollow silica reacted with 8.8 mole titanium butoxide solution. Transmittance observed on substrate of the $TiO_2$ shell-nano hollow silica showed effective absorption of 200-300 nm UV light without deterioration of visible light transparency.

• Journal of Industrial Technology
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• v.29 no.B
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• pp.133-137
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• 2009

This paper presents the development of smart road line lamp system consisting light control device. It can perform the individual power control or partial on/off control of a LED lamp by control center and can detect the error of the LEDs by current sensing. Also, the ability to control the brightness and period of on/off by detecting the car's existence. This light control circuit consists of road line lamp unit device. It can give a lot of solutions when the server, which controls the whole system, is operated through CDMA(Code-Division Multiple Access) network.

• 한국정보디스플레이학회:학술대회논문집
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• 2009.10a
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• pp.1511-1514
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• 2009

Organic light emitting layer in OLED device was formed by gravure printing process in this work. Organic surface coated by gravure printing typically showed relatively bad uniformity. Thickness and roughness control was characterized by applying various mixed solvents in this work. Poly (N-vinyl carbazole) (PVK) and fact-tris(2-phenylpyridine)iridium($Ir(ppy)_3$) are host dopant system materials. PVK was used as a host and Ir(ppy)3 as green-emitting dopant. To luminance efficiency of the plasma treatment on etched ITO glass and then PEDOT:PSS spin coated. The device layer structure of OLED devices is as follow Glass/ITO/PEDOT:PSS/PVK+Ir(ppy)3-Active layer /LiF/Al. It was printed by gravure printing technology for polymer light emitting diode (PLED). To control the thickness multi-printing technique was applied. As the number of the printing was increased the thickness enhancement was increased. To control the roughness of organic layer film, thermal annealing process was applied. The annealing temperature was varied from room temperature, $40^{\circ}C$, $80^{\circ}C$, to $120^{\circ}C$.

• Journal of the Korean Ceramic Society
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• v.54 no.5
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• pp.429-437
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• 2017

Micro hollow plate type silica with low refraction properties was synthesized and its hollow structure was applied as an optical structure to develop a light diffusion material that simultaneously satisfies the requirements of good light diffusibility, high transmissibility, and high luminance. The developed light diffusion material was applied to a light diffusion film and the film's optical properties were assessed. Hollow silica was synthesized by precipitation method using $Mg(OH)_2$ core particles, sodium silicate, and ammonium sulfate as the silica precursors. The concentration of the silica precursor was adjusted to control hollow silica shell thickness. The total light transmittance of the light diffusion film composed of the hollow silica was 94.55%, which was 4.57% higher than that of the PC film; new film's haze was 71.20%, which was 70.9% higher. Furthermore, the luminance increased by 5.34% compared to that of the light source. The reason for the results is not only that the micro plate type hollow silica, which has a low refractive property, played a role in reducing the difference in refractive index between the medium boundaries, but also that there was a light-concentrating effect due to the changing of light paths to the front direction inside the hollow structure. Optical simulation verified the enhanced optical properties when hollow silica was applied to the light diffusion film.

• Architectural research
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• v.7 no.2
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• pp.47-54
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• 2005

A photoelectric dimming control system for a small private office space with a double skin envelope system was analyzed for the purpose of examining optimum control performances under a variety of daylight conditions. Computer simulations were performed for the three different photosensor types positioned at the center of ceiling in the space. They were applied in both a south and north-facing room. Daylight conditions were a fixed horizontal venetian blind on an external envelope and a retractable shading device on an internal envelope under a clear, intermediate and overcast sky at different times of a day and year. Partially-shielded photosensors provided good control performances providing the required electric light output under clear and intermediate sky conditions. Unshielded photosensors failed to provide necessary illuminance levels producing less electric output and fully-shielded photosensors generally provided excessive light output. Reasonable electric lighting energy savings were achieved except under overcast sky conditions where the control system did not contribute to energy savings due to the less daylight through envelopes. The retractable shading device covering 50% of the internal envelope reduced energy savings up to 19.62%, but the workplane illuminance levels were maintained within recommended ranges. The coefficients of determination between workplane illuminance and photosensor illuminance due to daylight ranged from 0.74 to 0.98. Partially-shielded conditions provided best correlations and the north-facing room yielded stronger correlation than the south-facing room.

• Proceedings of the KSR Conference
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• 2003.05a
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• pp.139-144
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• 2003

This study was aimed to establish failure management plan of the rubber-tired AGT light rail vehicle for its safety case, which was developed according to the Korean standardized specifications for the light rail vehicle. Vehicular 9 failure modes anticipated during the system operation were considered, which are single malfunction of redundant equipment, malfunction of train radio, public address and air compressor, battery, main circuit NFB trip, on-board ATO control device malfunction, on-board ATP control device malfunction, fail of brake release, flat tire, train emergency door open.

• Journal of the Korean Society for Precision Engineering
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• v.21 no.4
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• pp.79-87
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• 2004

The light pattern reflected from a machined surface contains some information like roughness and profile on the projected surface as expected in the Beckmann-Spizzichino model. In applying the theory into a real reliable measuring device, many parameters such as incident light power, wave length, spot size should be kept a constant optical value. However, the reflected light power is likely to change with the environmental noise, the variations of the light source, the reflectivity of the surface, etc. even though the incident light power is constant. In this study, a method for adjusting the incident light power to keep the reflected light power projected on a CMOS image sensor constant was proposed and a simple adjustment algorithm based on PI digital control was examined. Experiments verified that the proposed method made the surface roughness measurement better and more reliable even under variations of the height of light source.