• Title/Summary/Keyword: Light emitting diode (LED)

Search Result 856, Processing Time 0.036 seconds

Effects of LED Light Quality of Urban Agricultural Plant Factories on the Growth of Daughter Plants of 'Seolhyang' Strawberry

  • Lee, Kook-Han
    • Journal of Environmental Science International
    • /
    • v.27 no.10
    • /
    • pp.821-829
    • /
    • 2018
  • This study was conducted to examine the influence of Light-Emitting Diode (LED) light quality in urban agricultural plant factories on the growth and development of Seolhyang strawberry daughter plants in order to improve the efficiency of daughter plant growth and urban agriculture. LED light quality by demonstrated that above-ground growth and development were greatest for daughter plant 2. Daughter plant 1 showed the next highest growth and development, followed by daughter plant 3. Among the different qualities of LED light, the stem was thickest and growth rate of leaves was highest for R + B III (LED quality: red 660 nm + blue 450 nm/photosynthetic photon flux density (PPFD): $241-243{\mu}mol{\cdot}m^{-2}{\cdot}s^{-1}$) and lowest for R (red $660nm/115-117{\mu}mol{\cdot}m^{-2}{\cdot}s^{-1}$). Plant height, leaf width, petiole length, and the leaf growth rate were highest for W (white fluorescent lamp/$241-243{\mu}mol{\cdot}m^{-2}{\cdot}s^{-1}$) and lowest for R + B I (red 660nm+blue 450nm/$80-82{\mu}mol{\cdot}m^{-2}{\cdot}s^{-1}$). For above-ground growth and development, as the plants surpassed the seedling age, mixed light (red + blue), rather than monochromatic light (red or blue), and higher PPFD values tended to increase development. Regarding the quality of the LED light, daughter plant 2 showed the highest chlorophyll content, followed by daughter plant 1, and daughter plant 3 showed the least chlorophyll content. When the wavelength was monochromatic, chlorophyll content increased, compared to that when PPFD values were increased. Mixed light vitality was highest in daughter plant 2, followed by 1, and 3, showed increased photosynthesis when PPFD values were high with mixed light, in contrast to the results observed for chlorophyll content.

A study on the accommodation of common LED to shipboard (육상용 LED 램프의 선박 적응력에 관한 연구)

  • Jeong, Ji-Hyun;Park, Hwan-Chul;Kim, Yong-Joo;Seo, Sang-Do;Han, Seung-Jae;Kim, Min-Sok
    • Journal of the Korean Society of Fisheries and Ocean Technology
    • /
    • v.46 no.4
    • /
    • pp.503-508
    • /
    • 2010
  • Common LED (Light Emitting Diode) lamp has many advantages to compare with fluorescent lamp, long life and no pollution matter like the mercury. The LED lamp is a good light source especially for shipboard lighting because of its compact structure which prevents explosion and shock. Also, low maintenance cost is expected due to its longer life time in comparison with conventional lamps. The LED lamp, however, need some estimates that change of voltage and frequency, vibration, moisture on board to definite accommodation of the LED lamp to shipboard. The purpose of this study is to compare physical properties of a fluorescent lamp with one of the common LED lamp so as to analyze accommodation of common LED lamp on board. This study was carried out in two stages. First, temperature, humidity of illumination, voltage, electric current, frequency and electric power were measured by using experimental equipments. Second, a comparative analysis of consumption electric power, annual oil charge, annual CO2 emission and lamp life time, etc of the fluorescent lamp and common LED one was made. As a result of the study, the consumption electric power of fluorescent lamp was 50% higher than one of the common LED lamp. As a result of measuring life time, it was found that life time of common LED lamp was more about 3.5 fold than one of the fluorescent lamp. Considering these results, it's thought that common LED lamp is verified that energy saving is possible and using is possible as substitute for fluorescent lamp on board.

Implementation of Visible Light Communication System Modulated by a Switching Driver Circuit of Lighting LED (조명용 LED의 스위칭 구동 회로로 변조되는 가시광 통신 시스템의 구현)

  • Cho, Sang-Ho;Han, Sang-Kyoo;Roh, Chung-Wook;Hong, Sung-Soo;Jang, Byung-Jun
    • The Journal of Korean Institute of Electromagnetic Engineering and Science
    • /
    • v.21 no.8
    • /
    • pp.905-910
    • /
    • 2010
  • In this paper, visible light communication(VLC) system modulated by a switching driver circuit of lighting light emitting diode(LED), not only for illumination but also for optical wireless communication, is implemented. Presented system could overcome the drawbacks of prior linear modulation technique such as low efficiency, heat generation, and limits to realization of high power lighting LED. Experimental results from the realized digital audio system are presented to confirm the superiority of the proposed circuit. Our prototype achieves a transmission data rate of 10 Mbps with a radius of 1.5 meters using 20 W output power, and the signals were detected successfully.

Development of Zygotic Embryos and Seedlings is Affected by Radiation Spectral Compositions from Light Emitting Diode (LED) System in Chestnut (Castanea crenata S. et Z.)

  • Park, So-Young;Kim, Man-Jo
    • Journal of Korean Society of Forest Science
    • /
    • v.99 no.5
    • /
    • pp.750-754
    • /
    • 2010
  • Among the environmental conditions employed in micropropagation, light quality plays an important role in growth, specially morphogenesis and photosynthesis. The effect of radiation quality (350-740 nm) on the development and growth of zygotic embryos and in vitro plantlets of open-pollinated chestnut (Castanea crenata S. et Z.) were studied. Two types of explants were exposed for 4 weeks to cool white (W, as control), monochromatic red (R, peak emission 650 nm), monochromatic blue (B, peak emission 440 nm), red+blue (R+B, 1:1), or red+far-red (R+Fr, 1:1, far-red peak emission 720 nm) radiation from a light-emitting-diode (LED) system. While the zygotic embryos showed positive photoblastic behavior, their germination was inhibited by blue radiation. Hypocotyl elongation and root development were promoted by red radiation. The emergence of primary leaf and its expansion were faster under blue than under red radiation. In the plantlets, red and red+far-red radiation significantly increased the formation and growth of the root, whereas blue light reduced rooting. Therefore, radiation quality appears to influence some steps in the development of zygotic embryos and plantlets in the chestnut.

Prototype Implementation of VLC Upstream Transmission Using Focused IR-LED (집광된 IR-LED를 이용한 가시광 통신 상향 전송 프로토타입 구현)

  • Jang, Yunseon;Choi, Kyungmook;Ju, MinChul;Park, Youngil
    • The Journal of Korean Institute of Communications and Information Sciences
    • /
    • v.37C no.9
    • /
    • pp.784-790
    • /
    • 2012
  • In this paper, we propose a upstream transmission method to extend coverage in visible light communication (VLC) systems. We extend transmission distance by using focused infrared(IR) light emitting diodes(LEDs). Since the focused light covers just limited area, it might have a difficulty in transmitting data if the transmitter and receiver are not properly aligned. To solve this problem, we arrange multiple IR-LEDs in different direction and select a single best performing IR-LED among multiple IR-LEDs. Also, the transmission performance is periodically checked and another IR-LED is reselected to support the required quality of service (QoS) and to minimize battery consumption required by a mobile terminal.

Characterizations of Luminance for Varied LED Based Surface Lighting Designs (LED 면광원에서 패키지 수량에 따른 휘도변화 특성)

  • Lee, Tae-Hoon;Choi, Seong-Dae
    • Journal of the Korean Society of Manufacturing Process Engineers
    • /
    • v.15 no.6
    • /
    • pp.70-76
    • /
    • 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.

Analysis of the spectral characteristics of white light-emitting diodes under various thermal environments

  • Jeong, Su-Seong;Ko, Jae-Hyeon
    • Journal of Information Display
    • /
    • v.13 no.1
    • /
    • pp.37-42
    • /
    • 2012
  • An empirical functional form was suggested for the analysis of the emission spectrum of high-power light-emitting diode (LED) consisting of a sharp blue peak from the LED chips and a broad yellow peak from the phosphor layer. The peak positions, half widths, shape parameters, and amplitudes of these two peaks were reliably obtained as a function of the temperature, and the results were discussed qualitatively in relation with the junction temperature. The adoption of an inert liquid was found to have significantly reduced the LED temperature and the color shift of the emitted light. The phenomenological approach used in this study may be helpful in the simulation of the LED spectrum under various thermal conditions, and may thus be helpful in the improvement of the device performance.

Technology Trends and Technology Development of Marin Lantern (점멸식 해상용 등명기 기술개발 동향 및 개발 사례)

  • Yang, Hyun-Kyoung
    • Proceedings of the Korean Institute of Navigation and Port Research Conference
    • /
    • 2017.11a
    • /
    • pp.220-221
    • /
    • 2017
  • The initial light emitting diode (LED) has been used as a display device for various mechanical devices due to its low power. The development of LED technology has made it possible to express color with high power and high brightness. Therefore, it is used as a display such as a traffic signal, a large electric signboard, and an automobile display, and is also adapted as an indoor or outdoor light source such as an incandescent or a fluorescent lamp which requires the high luminance. The bulb of marine lantern, which is used for the aids to navigation, was replaced to LED. The first marine LED lantern was manufactured using multiple LEDs. However, if the optical design is renewed by the development of LED or even if a few LEDs are used, it is possible to satisfy the brightness and the light distribution required by the marine LED lantern.

  • PDF

A New type $1.0\;mm\;{\times}\;0.5mm$ Light Emitting Diode using AlInGaN cell structure and Its Display Module

  • Park, Book-Sung;Kim, Sung-Woon;Lee, Seon-Gu;Son, Sung-Il;Kim, Eun-Tae;Kim, Chul-Ju
    • 한국정보디스플레이학회:학술대회논문집
    • /
    • 2008.10a
    • /
    • pp.557-560
    • /
    • 2008
  • The main goal of this work is to fabricate light emitting diode (LED) module and apply it to mobile handset. We first fabricated the blue-color LED based on the AlInGaN cell structure with size of $200\;{\mu}m\;{\times}\;200\;{\mu}m$. Also we proposed a new $1.0\;mm\;{\times}\;0.5\;mm$ (1005size) packaging procedure for the LED cell. Thus the overall dimension of our LED cell was as small as $1.0\;mm\;{\times}\;0.5\;mm\;{\times}\;0.4\;mm$ ($W\;{\times}\;L\;{\times}\;T$). As far as we knew it was the first time that this small LED cell dimension had been fabricated and operated.

  • PDF