• Journal of the Korea Academia-Industrial cooperation Society
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• 제13권1호
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• pp.296-305
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• 2012

In this paper, we develop about glare phenomenon at security light caused by light source's straight characteristic, maintaining uniformity ratio of illuminance as high, have long light distribution not by symmetry of rotation but a single axis. we develop second lens for security light that lack of light distribution phenomenon at each of security light can be solved. Our developed light system design satisfies lighting standard of security light's and shape of lens is single lens. so our lens optimizes designing or analysis by using lighting design and interpretation program. Making a Mock-up to do real measure, we have intensity of illumination and maintaining uniformity ratio of illuminance measurement data.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• 제25권9호
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• pp.750-754
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• 2012

An LED (light emitting diode) has the advantages of lower power consumption, energy saving, high efficiency, long lifetime, and environmental friendliness so that it has been getting the spotlight as a next-generation light source. Thus, the application range of an LED has been extended to various fields including indoor and outdoor lighting. Recently, the high efficient LED lighting has been developed, an LED has been extended its market rapidly every year and is expected to replace the general light source within near future. In this study were measured electrical and optical properties for 6 types of LED bulbs which are being developed to replace the general incandescent lamps, and were analysed under the standard of the omnidirectional lamp required by the Energy Star.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 한국정보통신학회 2018년도 춘계학술대회
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• pp.641-642
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• 2018

LED-based visible light communication requires separate transmission and reception equipment and is capable of communication only in the range of the light source. Also, there is an advantage that it can be used in a frequency sensitive area using a visible light band. Research is needed to apply these advantages and characteristics to various fields. In this paper, we implemented and verified the functions of the visible light communication system using broadcast methods.

• Journal of Ginseng Research
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• 제36권2호
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• pp.198-204
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• 2012

An light-emitting diode (LED)-based light source was used as a monochromatic light source to determine the responses of raw ginseng roots (Panax ginseng Meyer) to specific emission spectra with respect to the production of ginsenosides. The ginsenoside content in the ginseng roots changed in response to the LED light treatments at $25^{\circ}C$ relative to the levels in the control roots that were treated in the dark or at $4^{\circ}C$ for 7 d. Ginseng roots were exposed to LEDs with four different peak emission wavelengths, 380, 450, 470, and 660 nm, in closed compartments. Compared with the control $4^{\circ}C$-treated roots, roots that were treated with 450 and 470 nm light showed a significantly increased production of ginsenosides (p<0.05), with increases of 64.9% and 74.1%, respectively. The contents of the ginsenosides $Rb_2$, Rc, and $Rg_1$ were significantly higher (p<0.05) in the 450 and 470 nm-treated root samples. The ratio of protopanaxadiol ginsenosides ($Rb_1$, $Rb_2$, Rc, and Rd) to protopanaxatriol ginsenosides ($Rb_1$, $Rb_2$, Re, and Rf) was significantly higher (p<0.05) in the 450 and 470 nm-treated root samples than in the control $4^{\circ}C$-treated roots. This is the first report that demonstrates the increase and conversion of ginsenosides in raw ginseng roots in response to exposure to LED light.

• The Transactions of the Korean Institute of Power Electronics
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• 제26권1호
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• pp.9-15
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• 2021

In multi-string light-emitting diode (LED) driver system, current balancing is crucial because the brightness of LED is directly related to its forward current. This paper presents a novel LED current balancing topology using current-fed Z-source converter. With the proposed structure, currents flowing through two LED strings are automatically balanced owing to the charge-balance condition on capacitors. Operation of the proposed converter is simple and the proposed converter uses only one active switch and one diode. Moreover, low-side gate driving can be used to operate the active switch. To verify the operation of the proposed LED current balancing converter, a prototype is built and tested with different numbers of LEDs.

• Journal of Environmental Science International
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• 제33권5호
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• pp.305-322
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• 2024

The aim of this study was to investigate the effects of artificial light sources on the germination and seedling vigor of lettuce, aiming to identify the optimal artificial light source for producing high-quality seedlings. Lettuce cultivar of 'Tomalin' and 'Seonpunggold' exhibited the highest seed emergence in the Metal halide(MH) lamp and High-pressure sodium(HPS) lamp treatment group, while the emergence rate parameter, T50, was the fastest in the HPS lamp treatment group. Both cultivars showed good growth characteristics such as number of leaves, root length, and stem diameter under RGB-LED, and their seedling vigor was excellent as well. The plant height was smallest in the Red + Green + Blue LED treatment, but the leaves were round and thick, resulting in higher biomass and dry weight. Single light sources of Red LED and Blue LED led to reduced growth compared with that under the mixed light treatments. Chlorophyll content in lettuce varied with the type of artificial light, with both cultivars exhibiting the highest chlorophyll content in the Red + Green + Blue LED treatment. The most suitable artificial light for lettuce seedling growth was the Red + Green + Blue LED treatment.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• 제24권1호
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• pp.42-46
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• 2011

Light can be divided into ultraviolet rays, visible rays, and infrared rays depending on the wavelengths. Visible rays with specific wavelength are those predominantly used for would treatment. Especially low level laser irradiates into cells, effectively stimulating cellular tissues and activating cellular function. This study was intended to verify the effect of white LED irradiation therapy on wound recovery in animal tests by applying white LED irradiator, which was independently designed and developed to emit beams of similar wavelength to that of a laser. The designed LED Irradiator was used to find out how white LED light source affected the skin wound of SD-Rat(Sprague-Dawley Rat). We divided the participants into two groups; white LED irradiation group which was irradiated 1 hour a day for 9 consecutive days, and none irradiation group. The results showed that the study group had lower incidence of inflammation and faster recovery, compared with the control group.

• Journal of Biomedical Engineering Research
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• 제28권2호
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• pp.265-270
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• 2007

Polarization imaging systems have been widely used to selectively characterize skin lesions. Nevertheless, current systems are used in single-mode due to the limitations of a fixed polarization mode and a single-working distance of light source, in which uniform light distribution is achieved on target area. To address such limitations, we developed a variable polarization imaging system based on multi-working distance of light source for various clinical diagnoses. In this study, we characterize the imaging system and present experiment results demonstrating its clinical usefulness. The imaging system consists of a CCD color camera, linear polarization filters, and a single-layered LED ring light source which provides uniform light distribution at multi-working distances. The first polarizer was placed on the light source and the second polarizer placed on objective lens provides continuous linear polarization angle from $0^{\circ}\;to\;90^{\circ}$. The clinical efficacy of the imaging system was investigated by acquiring and analyzing clinical images of skin wrinkle and dental plaque. With the experiments, we verified the potential usefulness of the imaging system for other clinical applications.

• Journal of the Korean Society of Manufacturing Process Engineers
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• 제15권6호
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• pp.70-76
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• 2016

Commercialization of surface lighting using Light Emitting Diodes (LED) has embraced the advance to Organic Light Emitting Diode (OLED) technology. This is necessary to achieve light-efficiency-improvement and longer component life. The range of application of LED lighting for both interior and outdoor lights has been gradually expanding. Automobiles and home appliances are now included. In the case of LED surface lighting in a domestic refrigerator, achieving high efficiency requires optimization of the number of LEDs in a pack. Optimization is also required in the design stage of development with regard to the conversion of the light source type from point light sources to the surface light type. This paper addresses these design problems. It presents a study of brightness variations for design solutions that differ from the existing technology in both the number of LED packages and use of Light Gathering Power (LGP) information. The intention is to facilitate production of high brightness LED surface lighting for domestic refrigerators.

• Journal of Broadcast Engineering
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• 제15권1호
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• pp.76-88
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• 2010

Recently, LED background image devices are used for the production of broadcasting programs. But the effective advantages of LED background image devices are not realized for good HD video quality because the correlations between lighting sources and LED background image devices are not analyzed yet. In this paper, we analyze the color change and light intensity that lighting sources and the light intensity ratio of LED background images influence on a subject, making use of equipments used in real broadcasting, and examine the correlations between HD video quality and the light intensity ratio of LED background images. As a result in this experiment, the video is most expressed having an 20[IRE] effect on a subject when the light intensity of LED background image is 6%. When the LED background image is light, the light and darkness of video is distorted and when the LED background image is dark, the colors of image are distorted.