• Journal of Bio-Environment Control
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• v.27 no.3
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• pp.199-205
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• 2018

The aim of this study was to confirm that effects of supplemental LED illumination on a strawberry yield and fruit quality when strawberry grown on a bottom bed to be deficient ambient light due to shading of a upper bed during cultivation by a two-bed bench system. A strawberry was cultivated as a drip irrigation system in the two-bed bench system filled with a strawberry exclusive media from October 2015 to January 2016. The upper and the bottom bed without LED illumination for growth of a strawberry were using as a control. For LED light treatments, from 10 am to 4 pm, we illuminated LEDs as $100{\mu}mol{\cdot}m^{-2}{\cdot}s^{-1}$ of light intensity by using blue, red, and mixing LED (blue plus red) on the strawberry plants of the bottom bed. In the yield of strawberry fruit, the strawberry grown on the bottom bed treated with the blue LED significantly increased compared with that of the bottom bed part control, and increased to by near 90% of the strawberry output of the upper bed part control. The soluble sugar content of strawberry fruit grown on the upper bed part control and on the bottom bed illuminated with blue or mixed LED was higher than that of red LED and the control of the bottom bed. The content of anthocyanin was the highest increased in the strawberry grown on the upper bed part control that received a lot of ambient light, however when comparing only the bottom bed, strawberry fruits grown on all LED treatments were higher than that of the control. Therefore, we considered that using of the blue LED light on the bottom bed of two-bed bench system during strawberry cultivation is advantageous for the increase of yield and improvement of fruit quality.

• Journal of the Korean Society for Marine Environment & Energy
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• v.15 no.4
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• pp.323-329
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• 2012

In this study, a new optical method for oil detection using an analysis the light-absorption image of separate oil-water mixture with a LED illumination is described. To obtain an information about the presence of oil on water and the thickness of oil, the intensity of light-absorption images acquired through CCD is analyzed. To select the optimal wavelength of the light source, the experiment is conducted using several LEDs having four different wavelength. In the case of using a blue LED having 465 nm wavelength, an intensity decreasing tendency of light-absorption image is obvious and clear. To identify the applicability of sensing system at the real sea condition, experiments are conducted as varying the brightness and water surface angle. Through this research, new optical oil detection methodology is proposed using the absorption difference between water and oil with single-wavelength LED and CCD.

• Advances in materials Research
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• v.3 no.4
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• pp.227-232
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• 2014

$Ce^{4+}$, $Eu^{3+}$, $Tb^{3+}$ co-doped $Ca_3Si_3O_8F_2$ phosphor was synthesized via solid state reaction method using $CaF_2$, $CaCO_3$ and $SiO_2$ as raw materials for the host and $Eu_2O_3$, $CeO_2$, and $Tb_4O_7$ as activators. The luminescent properties of the phosphor was analysed by spectrofluorophotometer at room temperature. The effect of excitation wavelengths on the luminescent properties of the phosphor i.e. under near-ultraviolet (nUV) and visible excitations was investigated. The emission peaks of $Ce^{4+}$, $Eu^{3+}$, $Tb^{3+}$ co-doped $Ca_3Si_3O_8F_2$ phosphor lays at 480(blue band), 550(green band) and 611nm (red band) under 380nm excitation wavelength, attributed to the $Ce^{4+}$ ion, $Tb^{3+}$ ion and $Eu^{3+}$ ions respectively. The results reveal that the phosphor emits white light upon nUV (380nm) / visible (465nm) illumination, and a red light upon 395nm / 535nm illumination. RE ions doped $Ca_3Si_3O_8F_2$ is a promising white light phosphor for LEDs. The emission colours can be seen using Commission international de l'eclairage (CIE) co-ordinates. A single host phosphor emitting different colours under different excitations indicates that it is a potential phosphor having applications in many fields.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.50 no.4
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• pp.447-454
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• 2014

The marine microalgae Chaetoceros calcitrans was cultured under a fluorescent lamp (CON) and light-emitting diodes (LEDs) of various wavelengths (blue, LB; red, LR; green, LG; white, LW); changes in growth, fucoxanthin, chlorophyll-a, amino acid and fatty acid profiles were investigated. LR-exposed cultures exhibited the highest specific growth rate (SGR) (0.34), whereas LG-exposed cultures showed the lowest SGR (0.26). After cultivation for 10 days, the maximum dry cell weight (g/L) of LR-exposed cultures was significantly higher than that of those exposed to other light conditions (LR${\geq_-}$CON>LB${\geq_-}$LW${\geq_-}$LG). Eicosapentaenoic acid (EPA) levels were significantly higher in CON-exposed cultures compared to those exposed to LW (P<0.05), with no marked difference compared to those exposed to LB, LR and LG (P>0.05). The fucoxanthin content was highest in LB-exposed cultures ($6.3{\mu}g/mL$), whereas LW showed the lowest ($3.6{\mu}g/mL$; P<0.05). Chlorophyll-a content was highest in cultures exposed to LB compared to other light sources. These results suggest consistent differences in growth and biochemical composition after exposure to light of different wavelengths.

• Journal of Microbiology and Biotechnology
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• v.29 no.12
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• pp.1957-1968
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• 2019

Tetraselmis is a green algal genus, some of whose species are important in aquaculture as well as biotechnology. In algal culture, fluorescent lamps, traditional light source for culturing algae, are now being replaced by a cost-effective light-emitting diodes (LEDs). In this study, we investigated the effect of LED light of different wavelengths (white, red, yellow, and blue) on the growth of Tetraselmis suecica and its associated microbial community structures using the next-generation sequencing (NGS). The fastest growth rate of T. suecica was shown in the red light, whereas the slowest was in yellow. The highest OTUs (3426) were identified on day 0, whereas the lowest ones (308) were found on day 15 under red light. The top 100 OTUs associated with day 0 and day 5 cultures of T. suecica under the red and yellow LED were compared. Only 26 OTUs were commonly identified among four samples. The highest numbers of unique OTUs were identified at day 0, indicating the high degree of initial microbial diversity of the T. suecica inoculum. The red light-unique OTUs occupied 34.98%, whereas the yellow-specific OTUs accounted for only 2.2%. This result suggested a higher degree of interaction in T. suecica culture under the red light, where stronger photosynthesis occurs. Apparently, the microbial community associated with T. suecica related to the oxygen produced by algal photosynthesis. This result may expand our knowledge about the algae-bacteria consortia, which would be useful for various biotechnological applications including wastewater treatment, bioremediation, and sustainable aquaculture.

• Journal of Microbiology and Biotechnology
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• v.21 no.12
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• pp.1306-1311
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• 2011

Recombinant Rhodopseudomonas palustris, harboring the carotenoid-metabolizing gene crtI (CrtIBS), and whose color changes from greenish yellow to red in response to inorganic As(III), was cultured in transparent microplate wells illuminated with a light emitting diode (LED) array. The cells were seen to grow better under near-infrared light, when compared with cells illuminated with blue or green LEDs. The absorbance ratio of 525 to 425 nm after cultivation for 24 h, which reflects red carotenoid accumulation, increased with an increase in As(III) concentrations. The detection limit of cultures illuminated with near-infrared LED was 5 ${\mu}g$/l, which was equivalent to that of cultures in test tubes illuminated with an incandescent lamp. A near-infrared LED array, in combination with a microplate, enabled the simultaneous handling of multiple cultures, including CrtIBS and a control strain, for normalization by the illumination of those with equal photon flux densities. Thus, the introduction of a near-infrared LED array to the assay is advantageous for the monitoring of arsenic in natural water samples that may contain a number of unknown factors and, therefore, need normalization of the reporter event.

• Journal of Multimedia Information System
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• v.6 no.4
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• pp.293-302
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• 2019

In the past, there was a theory that influenza wasn't transmitted directly from birds but was infected to humans via swains. Recently, molecular level research has progressed, and it was confirmed that the avian influenza virus can directly infected to human lung and intestinal epithelial cells. Three pandemicsin the past 100 years were also infected to humans directly from birds. In view of such scientific background, we are developing a method for screening sick birds by monitoring the physiological characteristics of birds in a contactless manner with sensors. Here, the movement of respiratory muscles and abdominal muscles under autonomic innervation was monitored using a magnet and Hall sensor sewn on the thoracic wall, and other multimedia devices. This paper presents and discusses the results of experiments involving continuous periodic noise discovered during flight experiments with a data logger mounted on a Japanese pheasant from 2012 to 2015. A brief summary is given as the below: 1. Magnet and Hall sensor sewn to the left and right chest walls, bipolar electrocardiograms between the thoracic walls, posterior thoracic air sac pressure, angular velocity sensors sewn on the back and hips, and optical reflection of LEDs (blue and green) from the skin of the hips allow observation of periodic vibrations(fasciculations) in the waves. No such analysis has been reported before. 2. These fasciculations are presumed to be derived from muscle to maintain and control air sac pressure. 3. Since each muscle fiber is spatially Gaussian distributed from the sympathetic nerve, the envelope is assumed to plot a Gaussian curve. 4. Since avian trunk muscles contract periodically at all time, we assume that the sympathetic nerve dominates in their control. 5. The technique of sewing a magnet to the thoracic wall and measuring the strength of the magnetic field with a Hall sensor can be applied to screen for early stage of avian influenza, with a sensor attached to the chicken enclosure.

• Journal of Periodontal and Implant Science
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• v.48 no.3
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• pp.164-173
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• 2018

Purpose: The aim of this study was to evaluate the antimicrobial effect of a newly devised toothbrush with light-emitting diodes (LEDs) on Porphyromonas gingivalis attached to sandblasted and acid-etched titanium surfaces. Methods: The study included a control group, a commercial photodynamic therapy (PDT) group, and 3 test groups (B, BL, and BLE). The disks in the PDT group were placed in methylene blue and then irradiated with a diode laser. The B disks were only brushed, the BL disks were brushed with an LED toothbrush, and the BLE disks were placed into erythrosine and then brushed with an LED toothbrush. After the different treatments, bacteria were detached from the disks and spread on selective agar. The number of viable bacteria and percentage of bacterial reduction were determined from colony counts. Scanning electron microscopy was performed to visualize bacterial alterations. Results: The number of viable bacteria in the BLE group was significantly lower than that in the other groups (P<0.05). Scanning electron microscopy showed that bacterial cell walls were intact in the control and B groups, but changed after commercial PDT and LED exposure. Conclusions: The findings suggest that an LED toothbrush with erythrosine treatment was more effective than a commercial PDT kit in reducing the number of P. gingivalis cells attached to surface-modified titanium in vitro.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2003.07b
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• pp.1038-1042
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• 2003

LED(Light Emitting Diodes)를 이용한 LCD 백라이트는 현재까지 모바일용의 $2{\sim}3$ 인치정도의 소형모델에서 상용화되고있다. 현재 동종분야에서 $5{\sim}7$ 인치 이상의 중대형에서는 아직 검토나 개발단계인 것으로 파악되고 있다. LED의 특징인 장수명, 고색순도, Robustness 등의 장점에도 불구하고 광효율이나 경제적측면에서 아직 형광램프 Type 에 비해 개선점이 남아있는 것도 개발지연 이유중의 하나다. 최근에 일부 광원업체에서 소비전력 5W로 높은 출광효율을 갖는 고휘도를 가진 LED가 개발되고있다. 고색재현성을 요구하는 TV등의 민수용 디스플레이시장이 커지는 현 추세에 한 방법으로 3색의 고휘도 LED광원을 사용한 백 라이트를 개발했다. R(Red), G(Green), B(Blue)의 3색 점광원 다수를 이중도광판 구조의 장변에 일정 간격으로 배열하여 최종 출사면에서 백색이 되도록 소정의 구성비로 설계하였다. 점광원간의 간격으로 인해 발생되는 혼색도를 보완하기위해 광원과 출사면까지의 광경로를 점광원이 아닌 튜브형의 형광광원 사용시보다 일정량 길게 설계해야 되는데, 이것으로 인해 출광효율이 형광램프구조에 비해 떨어지는 결과로 나타났다. 본 연구에서는 17인치 모니터구조의 백라이트에서 색재현성 105%와 소비전력 67W에서 표면휘도 $2000cd/m^2$ 정도를 달성하였다.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.25 no.9
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• pp.755-758
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• 2012

We developed a new solar simulator to evaluate a large-scale solar cell using seven kinds of LEDs (Infrared, Red, Yellow, Green, Blue, White and Ultra Violet LED). LED solar simulator can be displaced the existing solar simulator which has several demerits such as high power consumption and short lifetime. We have tried to fabricate LED solar simulator which fulfills the spectrum for AM 1.5G condition, and to verify the feasibility of LED solar simulator.