• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2007.06a
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• pp.429-429
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• 2007

In this study, it was investigated about the variation of luminance properties in LED backlight with geometrical shape such as prism or lens shape on the light-entering face. Generally, LED light source has the loss in backlight system because it has horizontal direction light. PMMA(Poly-Methyl-Meta-Acrylate) is used LGP(Light-Guide-Plate) in conventional backlight system. PMMA has low refraction angle. so that. horizontal direction light was not used in backlight system. The addition of geometrical shape in light-entering face in LGP improves the luminance characteristics because it prevents horizontal direction light generation in light-entering-face. Prism or lens shape in same pitch disposition was almost same without these treatment such as the value of 1% rising. Besides. It is particular that the gap of these shape such as the value of 0.407~0.22mm prevents horizontal direction light, so then it contributes luminance rising at 5.6%.

• Journal of the Semiconductor & Display Technology
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• v.17 no.2
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• pp.36-40
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• 2018

Point LED applied in Korea is applied to communication RCLED, but it is designed to be suitable for communication, so it does not meet requirements in fiber coupling rate and optical output. - Currently, domestic optical pipe manufacturers use general LEDs for light emitting devices, but Japanese products use high power point LEDs to develop superior point LED (RED 620 ~ 660nm).

• Journal of Biosystems Engineering
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• v.38 no.4
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• pp.279-286
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• 2013

Purpose: This study was conducted to analyze the utilization efficiencies of electric energy and photosynthetically active radiation of lettuce grown under red LED, blue LED and fluorescent lamps with different photoperiods. Methods: Red LED with peak wavelength of 660 nm and blue LED with peak wavelength of 450 nm were used to analyze the effect of three levels of photoperiod (12/12 h, 16/8 h, 20/4 h) of LED illumination on light utilization efficiency of lettuce grown hydroponically in a closed plant production system (CPPS). Cool-white fluorescent lamps (FL) were used as the control. Photosynthetic photon flux, air temperature and relative humidity in CPPS were maintained at 230 ${\mu}mol{\cdot}m^{-2}{\cdot}s^{-1}$, $22/18^{\circ}C$ (light/darkness), and 70%, respectively. Electric conductivity and pH were controlled at 1.5-1.8 $dS{\cdot}m^{-1}$ and 5.5-6.0, respectively. The light utilization efficiency based on the chemical energy converted by photosynthesis, the accumulated electric energy consumed by artificial lighting sources, and the accumulated photosynthetically active radiation illuminated from artificial lighting sources were calculated. Results: As compared to the control, we found that the accumulated electric energy consumption decreased by 75.6% for red LED and by 70.7% for blue LED. The accumulated photosynthetically active radiation illuminated from red LED and blue LED decreased by 43.8% and 33.5%, respectively, compared with the control. The electric energy utilization efficiency (EEUE) of lettuce at growth stage 2 was 1.29-2.06% for red LED, 0.76-1.53% for blue LED, and 0.25-0.41% for FL. The photosynthetically active radiation utilization efficiency (PARUE) of lettuce was 6.25-9.95% for red LED, 3.75-7.49% for blue LED, and 2.77-4.62% for FL. EEUE and PARUE significantly increased with the increasing light period. Conclusions: From these results, illumination time of 16-20 h in a day was proposed to improve the light utilization efficiency of lettuce grown in a plant factory.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2007.11a
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• pp.432-432
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• 2007

We studied optical simulation method for ultra slim backlight system. We designed 0.7mm thickness light guide plate and combined 48 white color LEDs for 12 inch wide size TFT-LCD. We designed flat shape PMMA light guide plate with both side patterned. It have vertical prism shape on upper side and ellipse dot pattern on the other side. We targeted 4500 nit brightness and uniform emission characteristic without hot spot or dark area. At first, we designed uniform emission area with more high brightness in center area and then, debugged light entering hot spot zone and direction of outgoing light flux. Although it was designing step, we obtained good result with reverse prism optical sheet and it had good repeatability because it was based on the stamper method in injection process without laser engraving or micro groove engraving method.

• Journal of the Institute of Electronics Engineers of Korea SC
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• v.44 no.5
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• pp.30-37
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• 2007

Hardware for monitoring the water quality is developed using water fleas. Water flea is a frequently used biological sensor for monitoring the water quality. Water fleas quickly respond to the incoming toxic water by changing their activity when they are exposed. By measuring the activity of water fleas, the incoming toxic water is instantly detected in real time. So far the measurement of activity of water fleas has been done with a system equipped with a light source of LED and a light detector of photo transistor. Water flea itself is, however, sensitive to light resulting in incorrect response and the system has two inconvenient separate parts of the light source and the detector. This paper suggests a system using a CCD camera instead of a light source and a detector. The suggested system processes the image data from the CCD camera in real time without any delay. The developed system becomes a part of the remote water monitoring embedded system.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2009.06a
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• pp.145-146
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• 2009

• Journal of Satellite, Information and Communications
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• v.11 no.1
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• pp.51-54
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• 2016

This paper present a method which resolves an optical discontinuity in bezel of digital signage using light guide film. On a polycarbonate film, a light guide film is bonded to produce refraction, reflection, diffraction of light. Arc shaped light guide film is assembled on the top LED light sources (red and green) to see light propagation through the film. When the two light sources (red and green) are mechanically attached at the end of the film, optical convergence brings new colors which have light wavelength between red and green. This result indicates that the light waveguide method could solve the light discontinuity on bezel of the digital signage system.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.17 no.4
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• pp.404-409
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• 2004

We fabricated photo-sensor for fluorescence detection in LOC. LOC is high throughput screening system. Our LOC screens biochemical reaction of protein using the immunoassay, and converts biochemical reaction into electrical signal using LIF(Laser Induced Fluorescence) detection method. Protein is labeled with rhodamine intercalating dye and finger PIN photodiode is used as photo-sensor We measured fluorescence emission of rhodamine dye and analyzed tendency of fluorescence detection, according to photo-sensor size, light intensity, and rhodamine concentration. Detection current was almost linearly proportional to two parameters, intensity and concentration, and was inversely proportional to photo-sensor size. Integrated LOC consists of optical-filter deposited photo-sensor and PDMS microchannel detected 50 (pg/${mu}ell$) rhodamine. For integrated LOC including light source, we used green LED as the light source and measured emitted fluorescence.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.29 no.4
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• pp.30-36
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• 2015

The principle of an illumination and projection system including LED light sources for a spot type stage lighting system was presented, and its optical system was designed with optimizing parameters by the analytical methods. A dichroic mirror incorporated with an illumination system to optimizing LED source positions and to obtain the compact system. The projection system was optimized with specific constraints such as a chromatic aberration, distortion aberration and angle of incidence angles. Optimized design system has a beam angle from $10^{\circ}$ to $45^{\circ}$, and its illuminance was 4,500lux at distance of 6m on the work plane.

• Journal of Sensor Science and Technology
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• v.31 no.1
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• pp.31-35
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• 2022

The efficacy improvement of the light emitting diode (LED) was studied for the realization of small-size, low power consumption, and highly sensitive bio-sensor instrument. The performance of the LED with Mg delta-doping at the interface of AlGaN/GaN super-lattice in p type cladding layer was simulated. The device with Mg delta-doping showed improved current, radiative recombination rate, electroluminescence, and light output power compared to the conventional LED structure. Under the bias condition of 5 V, the improved device exhibited 20.8% increase in the light output power. This is attributed to the increment of hole concentration from stable ionization of Mg in p type cladding layer. This result is expected to be used for the miniaturization, power saving, and sensitivity improvement of the bio-sensor system.