• Journal of Bio-Environment Control
• /
• v.18 no.4
• /
• pp.370-376
• /
• 2009

To produce uniform seedlings of tomato and cucumber with inexpensive way, their seedling quality by different light sources was investigated. The raising of seedling was performed by red LED (light emitting diodes), blue LED, red-blue mixed LED or fluorescent light with a fixed PPF(photosynthetic proton flux) level, about $40{\sim}60{\mu}mol{\cdot}m^{-2}{\cdot}sec^{-1}$. In the both tomato and cucumber, the rapid extension of hypocotyledonary axis was observed in Blue LED than fluorescent light, but opposite result was found in Red and mixed LED. During the nursery period of tomato and cucumber, the fresh weight was the highest in Red LED as 74% increasement in tomato and 74% in cucumber. In the case of seedling quality after the tomato nursery, there was no difference in the positions of 1st flower cluster and the number of bearing-flower per flower cluster by each light source. In case of cucumber, until 20th node, the setting ratio of female flower was higher in LED than fluorescent treatment, and also more healthy fruit setting was found in LED. Therefore, we assume that the Red or mixed (Red 2 + Blue 1) LED is more favorable to produce high quality tomato and cucumber seedlings in closed nursery facility.

• Korean Journal of Ecology and Environment
• /
• v.52 no.2
• /
• pp.171-177
• /
• 2019

Smart farm is a breakthrough technology that can maximize crop productivity and economy through efficient utilization of space regardless of external environmental factors. This study was conducted to investigate the optimal growth and physiological conditions of Chinese matrimony vine (Lycium chinense) with LED light sources in a smart farm. The light source was composed of red+blue and red+blue+white mixed light using a LED system. In the red+blue mixed light, red and blue colored LEDs were mixed at ratios of 1:1, 2:1, 5:1, and 10:1, with duty ratios varied to 100%, 99%, and 97%. The experimental results showed that the photosynthetic rate according to the types of light sources did not show statistically significant differences. Meanwhile, the photosynthetic rate according to the mixed ratio of the red and the blue light was highest with the red light and blue LED ratio of 1:1 while the water use efficiency was highest with the red and blue LED ratio of 2:1. The photosynthetic rate according to duty ratio was highest with the duty ratio of 99% under the mixed light condition of red+blue+white whereas the water use efficiency was highest with the duty ratio of 97% under the mixed light of red+blue LED. The results indicate that the light source and light quality for the optimal growth of Lycium chinense in the smart farm using the LED system are the mixed light of red+blue (1:1) and the duty ratio of 97%.

• Korean journal of applied entomology
• /
• v.61 no.4
• /
• pp.615-622
• /
• 2022

In this study, we sought to determine an appropriate LED light source that can be applied for the quality control of Aphidius colemani. Four LED light sources (385, 405, 450, and 660 nm) were evaluated in a Y-tube experiment (choice test) using a 5,000-k white LED as a control. The 385 nm LED light source was found to have attractant effect on A. colemani. In a no-choice test (Y-tube experiment) evaluating the remaining three LED light sources (385, 405, and 450 nm), the attractiveness of these light sources for A. colemani was high in the order 450 nm > 385 nm > 405 nm light, with no statistically significant differences between 450 nm and 385 nm. Given that 385 nm LED illumination may cause skin damage, we selected 450 nm LEDs for application in a device used for the quality control of A. colemani, which we subsequently demonstrated to have an attraction rate of 87.4%. We believe the findings of this study will make a valuable contribution to the quality control of natural enemies.

• Horticultural Science & Technology
• /
• v.31 no.4
• /
• pp.415-422
• /
• 2013

This study was conducted to establish the optimum LED light source and quality for growth of Wasabia japonica seedlings in the LED chamber plant factory system. The light treatments were combined with four colors LED (red, blue, white, far-red), irradiation time ratio of the red and blue LED per minute(1:1, 2:1, 5:1, 10:1), and duty ratio of mixed light (100%, 99%, 97%). The growth response of W. japonica was the greatest in the R + B mixed light treatment, and seedlings grown in the red LED alone was higher than blue LED alone in the monochromic radiation treatments. In the R + B mixed LED, 1:1 ratio of R and B was the best for total biomass and tiller production. In mixed light treatments, the growth response of W. japonica was highest in the 100% duty ratio with R + B mixed light, while that was highest in the 97% duty ratio with R + B + W mixed light. Leaf area and dry weight were increased in the red light treatment alone, while specific leaf area was increased in the blue light alone. With the increasing red LED light ratio, leaf area and dry weight of W. japonica was significantly increased under the R + B mixed light treatment. In mixed light treatments, the leaf growth responses of W. japonica was highest in the 97% duty ratio with R+B mixed light, while that was highest in the 100% duty ratio with R + B + W mixed light. For cultivating W. japonica in a plant factory, treating red LED supplemented with a blue light or higher ratio of the red to blue LED was benefit to promote the growth of W. japonica.

• Journal of Broadcast Engineering
• /
• v.15 no.4
• /
• pp.461-473
• /
• 2010

Since eco friendly and power saving products recently got into the limelight for the protection of environment, LED light technology has caught much of attention as the next generation broadcasting lighting. The newly introduced light source has such advantages as higher efficiency, longer life and its slim and compact forms leading to conveniency in installations. When combined with digital light control it gives more dynamic and various features to lighting. In this paper, used CIE standard for measuring light sources by their purposes and forms to make a comparative analysis of spectral distribution and color rendition of LED light source to those of existing lighting systems. By means of the cast shadowing and color reproduction tests I also tried to figure out the effects of LED lighting design on TV visuals where higher quality is crucial with the audience's increasing demands for quality image.

• Korean Journal of Food Science and Technology
• /
• v.45 no.6
• /
• pp.763-769
• /
• 2013

Soybean oil was stored in polyethylene for 12 weeks at $20^{\circ}C$. The influence of LED (light emitting diode) irradiation on four different wavelengths and fluorescent light was investigated. The pattern changes of volatile components in soybean oil was analyzed by electronic nose based on mass spectrometer. The obtained data from electronic nose were analyzed by discrimination function analysis. Under fluorescent light, the discriminant function first score (DF1) was significantly moved from positive position to negative one after 4-12 weeks. It means that the volatile compounds related to quality of lipid. It was shown to increase slowly due to green light of LED treatment, while blue and white LED light was influenced significantly as well as fluorescent light irradiation. Selection of LED irradiation would provide to keep good quality of soybean oil under distribution chain system.

• Journal of Bio-Environment Control
• /
• v.21 no.3
• /
• pp.220-227
• /
• 2012

This study was conducted to analyze the seeding quality of paprika and the growth and early yield after transplanting of paprika nursed under artificial light and natural light. In this study, blue LED, red LED, and white fluorescent lamps (FL) were used as artificial lighting sources. Photoperiod, average photosynthetic photon flux, air temperature, and relative humidity in a closed transplants production system (CTPS) were maintained at 16/8 h, $204{\mu}mol{\cdot}m^{-2}{\cdot}s^{-1}$, 26/$20^{\circ}C$, and 70%, respectively. Leaf length, leaf width, leaf area, top fresh weight and dry weight of paprika seedlings, and chlorophyll content in paprika leaves nursed under LED and fluorescent lamps for 21 days after experiment were significantly affected by light treatments. As compared with the control (white FL), leaf area of paprika grown under blue LED, red LED, and natural light was decreased by 63%, 63%, and 28%, respectively. Top dry weight of paprika grown under blue LED, red LED, and natural light was 64%, 50%, and 22%, respectively, compared with the control. Number of leaves on 18 days after transplanting showed with red LED, blue LED, and natural light by 86%, 84%, and 48%, respectively, compared with the control. On 114 days after transplanting, paprika nursed under blue LED and red LED had relatively short plant height. This result might be caused that the elongation of its internodes was suppressed by the illumination of sole blue or red light. Average number of fruits per plant harvested during 4 weeks after first harvest was 3.5 with red LED, 3.3 with blue LED, 1.0 with natural light, and 2.2 with control, respectively. Early yield of paprika nursed under red LED, blue LED, natural light, and control were 453 g/plant, 403 g/plant, 101 g/plant, and 273 g/plant, respectively. Larger fruit of 136 g was harvested with red LED treatment. Even though the early yield of paprika was greatly increased with artificial lighting, but total yield was almost similar as the harvest period after transplanting in greenhouses was lengthened. From the above results, we could understand that paprika nursed under white FL, blue LED, and red LED showed good growth after transplanting and was early harvested by a week as compared to the natural light. Therefore, the white FL, blue LED, and red LED as the artificial lighting sources in CTPS could be strategically used to enhance the seedling quality, to shorten the harvest time, and to increase the yield of paprika.

• 한국정보디스플레이학회:학술대회논문집
• /
• 2009.10a
• /
• pp.590-593
• /
• 2009

In the 2D local dimmable LED backlight system, each LED segment can be controlled separately. This can enhance the contrast ratio and reduce overall power consumption of LCDs. However, an artifact such as 'halo mura' can be observed around the bright object in the dark background. This is caused by the light leakage from the bright area into the dark one. Therefore, the 'halo mura' can be more easily observed in the oblique viewing direction. Thus, in this study, the perceivable degree of the halo mura is evaluated according to the level of the off-axis light leakage of LCDs. It is found that an acceptable degree of halo mura can be obtained in 2.0 cd/$m^2$ of the diagonal light leakage. In addition, the halo mura is unperceivable under 0.7 cd/$m^2$ of the diagonal light leakage which can be achieved with optimally compensated polarizers.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
• /
• v.25 no.11
• /
• pp.1-13
• /
• 2011

The purpose of this study is the realization of LED light environment closely resembling the Autumn daylight which people feel comfortable with. This research was conducted through an optical experiment and Emotional evaluation through human's eyes. Human beings are affected by the color of light, quality and light intensity. Unlike the past when human beings have worked mainly in daylight, the urbanites today spend most of the time in indoor spaces. Therefore, the artificial light is needed to strive toward a spectrum of daylight. This study is purposed to provide the pleasant light environment for human beings and build its database. This study course is expected to contribute to the new design methodology of the related fields under the development of the LED emotional lighting color.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
• /
• v.28 no.2
• /
• pp.142-147
• /
• 2015

The artificial light sources for growth of plant are usually high-pressure sodium lamp, metal haloids lamp, and fluorescent light; however, these light sources have relatively weaker Red and Blue lights that are necessary for growth of plants. Especially the effect of Photosynthetic Photon Flux Density (PPFD) is pointed out as the weakness. Meanwhile, LED light source can be selected by specific wavelength to greatly improve the effect of PPFD. In this regard, this paper aims to investigate the promotion of plant growth by measuring photosynthetic photon flux density (hereafter referred to as PPFD) according to changes in light quality of the LED light sources. Towards this end, LED light sources for plant growth were produced with 4 kinds of mono-chromatic lights and 6 kinds of combined lights by mixing red, blue, green and white lights. A comparative analysis was conducted to investigate the effects of optical properties and PPFD on plants (green leaf lettuce) using the produced light sources. The results monochromatic light has fastest growth rate, but plant growth conditions have poor. This being so, mixed light is suitable for the green leaf lettuce.