• Korean Journal of Organic Agriculture
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• v.24 no.1
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• pp.99-114
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• 2016

This study was conducted to evaluate effects of various eco light sources with various lighting distance in 'Viking' rose (Rosa spp.) on the growth and flowering quality to be applied for farm sites. Treatment included 10-, 20-, and 30-RL (-BL, -RBL, -FL, and -IL), which referred to red LED (blue LED, red+blue LED, fluorescent, and incandescent) lighting at 10 cm, 20 cm, 30 cm respectively, apart from flowers. NL referred to natural light as a control. Growth and flowering of 'Viking' rose were non-destructively measured at 4, 6, and 8 weeks after treatment (WAT). FL treatment increased plant height at 4, 6, and 8 WAT, regardless of lighting distance, with the shortest height observed for the NL-treated flowers. 30 RL treatment also increased plant height at 6 and 8 WAT. Stem diameter and number of leaves were not significantly different for all the treatments at 8 WAT, with the lowest values observed for RBL treated-flowers among the light source treatments. Number of root was the greatest for the 30 BL-treated flowers (10.0) but the fewest for the 30 FL (4.7). Length of flower neck at 6 WAT was the extended by 6~7 cm in the 10 FL and 20 FL treatments as well as by 5~6 cm in the 20 RL and 30 RL treatments, inducing 100% of flowering. NL increased $a^*$ (29) of flower color, with the lowest value (10) observed for 20 RL. All things considered, 30 RL would be the best interaction treatment of source and distance of eco light to improve plant height and flowering quality of 'Viking' rose.

• Korean Journal of Optics and Photonics
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• v.32 no.5
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• pp.220-229
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• 2021

The optical characteristics of high-power direct-lit white light-emitting diode (LED) lighting were investigated, where a quantum dot (QD) film was adopted to enhance the color-rendering index (CRI). The transmittance of the diffuser plate and the concentration of the QD film were varied in this study. The color coordinates and the correlated color temperature (CCT) did not show any appreciable change, while the CRI values increased slightly as the transmittance of the diffuser plate decreased. The investigated optical properties were nearly independent of the viewing angle, and the luminance distribution was close to Lambertian. The CCT decreased from approximately 6000 K to approximately 4000 K as the concentration of the QD film increased from 0 to 7.5 wt%, which was due to the enhanced red component in the emission spectrum. The CRI increased to approximately 95 for some optical configurations of the lighting. These results demonstrate that glare-free, color-changeable, high-rendering LED lighting can be realized by using a combination of a diffuser plate of appropriate transmittance and a red QD film.

• Proceedings of the KIPE Conference
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• 2004.07b
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• pp.851-854
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• 2004

This paper studies Optical Fiber(OF) - LED illuminated display board system for energy saving. The OF-LED illuminated display board system has PV modules, batteries, and charge & discharge system, and dynamic full color display controller. Both maximum power point tracker (MPPT) and constant current & constant current controls (CCVC) are used In govern the charging system. It can be improve the charging efficiency of battery. The objective of this thesis paper is to build advertisement lighting system with OF-LED in to charge a 12-volts lead acid battery by using a field wired PV array. We saved the maintenance cost and developed of advertisement effectiveness. To verify the proposed OF-LED illuminated display board system for energy saving, the detail simulation and experiment results indicate that operating characteristics are verified by experiment with a laboratory prototype in this paper.

• Transactions of Materials Processing
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• v.21 no.2
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• pp.131-137
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• 2012

With the advantages of power savings, increased life expectancy and fast response time over traditional incandescent bulb, LEDs are increasingly used for many applications including automotive, aviation, display, and special lighting applications. Since the high heat generation of LED chips can reduce service life, degrade luminous efficiency, and cause variation of color temperature, many studies have been carried out on the optimization of LED packaging and heat sinks. In this study, a fin expansion type cooling device using heat pipe, instead of a solid aluminum heat sink, was designed for LED security lightings based on thermal resistance analysis. Numerical analysis and experimental validation were carried out to evaluate its cooling performance.

• Journal of the Semiconductor & Display Technology
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• v.19 no.4
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• pp.1-5
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• 2020

By adapting black body leadflame and thin film type Green A filter, we successfully demonstrated night vision imaging system (NVIS) Green A compatible LED. Fabricated NVIS compatible LEDs show small form factor compared to that of commercialized NVIS compatible LED. Especially, NVIS radiance and chromaticity of MIL-STD-3009 specification can be satisfied simultaneously and easily by controlling the color temperature of the white LED as well as the concentration of the Green A dye and the thickness of the Green A filter. The optimal dye concentration of the NVIS Green A filter is expected to be about 1 wt%. The results of this study are expected to contribute to miniaturization, weight reduction and localization of avionic display and lighting devices.

• Journal of Environmental Science International
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• v.33 no.6
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• pp.383-402
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• 2024

Variations in lettuce growth and quality were observed depending on the type of artificial light source. The RGB LED treatment resulted in thick leaf development, leading to higher fresh weight, dry weight, and relative growth rates. Two cultivars, "Tomalin" and "seonpunggold," exhibited increased anthocyanin content and dark red leaf color under conditions of RGB LED treatment. Additionally, they exhibited high chlorophyll content under conditions of RGB LED and RGBFR LED treatments. Particularly, under Red LED treatment, the plants showed elongated leaves with narrow widths, resulting in a higher leaf shape index and a tendency towards leaf curling. Therefore, RGB LED lighting which appropriately blends red, blue, and green lights, is more effective than single lighr sources at improving lettuce growth and quality.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.14 no.4
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• pp.77-83
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• 2014

Visible light communication is a converging communication by technologies that enable solutions using the LED Lighting. There is a need to research about it in order to improve the performance of the wireless communication by using a Color LED and improve the efficiency of data. In this paper, Assume the General indoor communication environment and LED communication systems based on CSK-OFDM applied to a MIMO communication system, We studied about transmitting method of more efficient communication. After performing the simulation based on IEEE 802.15.7 Standardization, as a result of the analysis of performance, it was confirmed the there is a significant impact on the performance of SNR and BER performance by the transmitting method based on MIMO and external noise using the LED communication system based on CSK-OFDM.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.38C no.8
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• pp.725-732
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• 2013

Recently, various applications for LED lightings are growing continuously due to their better performances such as low power consumption, longer life time, operation speed, controllability, high quality color rendering, and sustainability. However, in developing the high-powered LEDs illumination system, heat-sink problem is one of the important obstacle. In this paper, a heat-sink design with multi-layered structure for high-powered LEDs is proposed, which is composed of metal core PCB, heat-pipes, heat-sink plates, and fans. And also, in this paper, a design for LED controls using DMX512 protocols through RS-485 communications is proposed, which is considered as de facto international standard in LEDs illumination control and is widely used in landscape lighting and stage lighting. In this paper, LED control and its application techniques are introduced and the method of wireless remote control for main controller is proposed.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.20 no.7
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• pp.1317-1324
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• 2016

Utilizing the Arduino platform to express the emotions that reflect the colors expressed the jewelry. Emotional color expression utilizes Plutchik's Wheel of Emotions model was applied to the similarity of emotions and colors. It receives the recognized value from the temperature, lighting, sound, pulse sensor and gyro sensor of a smart jewelery that can be easily accessible from your smartphone processes that recognize and process the emotion applied the rules of inference based on ontology. The emotional feelings color depending on the color looking for the emotion seen in context and applied to the smart LED jewelry. The emotion and the color combination of contextual information extracted from the recognition sensors are reflected in the built-in smart LED Jewelry depending on the emotions of the wearer. Take a light plus the emotion in a smart jewelery can represent the emotions of the situation, the doctor will be able to be a tool of representation.

• Proceedings of the KIEE Conference
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• 2006.07c
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• pp.1735-1736
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• 2006

As developing the information society, Lighting Emitted diode(LED) which is light source for illumination of next generation is attracted public attention. LED have many problem as narrow light view angle, high price, drift phenomenon of color coordinate, high heating problem for lower power, lower weight and small size. So, many researches have continued in a illumination as LED module type. in this problem, heating problem is very important and difficult and that is caused in decreasing phenomenon of brightness and drift phenomenon of color coordinate. so the problem of heating is urgent question for illumination of LED. In this paper, structural design of PCB changed as two type for solving the heating problem. also the properties of heating is analysed and optical properties is measured with heating image camera and spectrometer according to change in this design.