• New Physics: Sae Mulli
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• v.68 no.11
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• pp.1268-1274
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• 2018

Aircraft-warning lights are lights that are used to inform pilots in flight about the presence of buildings or dangerous objects. Currently, the light sources of most aircraft-warning lights have been replaced by light-emitting diodes (LEDs). However, the aircraft-warning lights that are installed do not meet the optical performance standards and may cause airplane collisions. Therefore, the use of such light poses a risk to aviation safety. In order to solve this problem, we designed a Fresnel lens with the same luminous intensity distribution ovef $360^{\circ}$ direction; thus, we collimated the light beam from the LED light source with a narrow beam divergence angle in the form of an array of aspheric pieces. After that, we designed and simulated an aircraft-warning-light optical system with a center luminous intensity of 20,000 cd and a vertical divergence angle of $3^{\circ}$ or more by optimizing the lens' tilt and the distance between the LED and the Fresnel lens.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.50 no.4
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• pp.413-420
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• 2017

The increase in the number of mud shrimps Upogebia major is a concern because of their negative effects on shellfish aquaculture, including Manila clam Venerupis philippinatum along the west coast of Korea. This study developed a behavioral analysis system for aquatic animals using a set of monochromatic light-emitting diode (LED) modules covering the visible light range at similar intervals. Movements of mud shrimp were monitored using a tracking system under illumination with infra-red light and an LED of 660 nm wavelength without provoking stimulation. The minimum light intensity needed to induce a photoresponse by the mud shrimp was $10{\mu}mole/m^2/s$ under the conditions tested. Of the six kinds of LED illuminations tested, the most sensitive response was obtained with illumination with the 505 nm LED, followed in order by LEDs with peak wavelengths of $525nm{\fallingdotseq}465nm$ > $405nm{\fallingdotseq}590nm$ > 660 nm. These findings should help to identify LED sources that efficiently induce movement of the mud shrimp and also for monitoring movement without stimulating.

• Journal of Bio-Environment Control
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• v.26 no.3
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• pp.208-214
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• 2017

This study aimed to determinate the effect of fluorescent light and light-emitting diodes on the leaf morphology, growth and antioxidant capacity of Salvia plebeia. The plants were grown for 56 days after transplanting (DAT) under the fluorescent light (FL) and LEDs (White, Red and Blue (R+B, ratio 2:1), Blue, Red LED) under the same light intensity and photoperiod ($130{\mu}mol{\cdot}m^{-2}{\cdot}s^{-1}$, 12 hours). Leaf length, width and number of Salvia plebeia at the 56 DAT were significantly higher under the FL and red LED, and lower in the RB LED and white LED. The highest fresh and dry weights of shoot and leaf area were observed in the red LED, followed by the FL and blue LED, and the lowest in the RB LED and white LED. After 21 DAT, leaf apinasty symptom was appeared in plants grown under red LED and RB LED. The chlorophyll content was lower in the red LED. The specific leaf weight, the ratio of leaf dry weight to area, was higher in the blue LED, and lowest in the FL. No significant difference in DPPH radical scavenging activity of Salvia plebeia under the different light sources. All the integrated results suggest that the FL light is a proper light conditions for a closed cultivation of Salvia plebeia.

• Journal of the Korean Society for Precision Engineering
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• v.29 no.9
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• pp.931-937
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• 2012

In this study, we assessed environmental impacts of compound humidifiers using environmental life cycle assessment and presented the ways to improvements in energy consumption of them. We found eco-design parameters and $CO_2$-eq emissions in each stage of raw material acquisition, manufacturing, transportation, use and disuse in life cycle of the compound humidifiers. The highest $CO_2$ emission is found to be in the stage of use among all stages of life cycle, which is mainly due to power consumption in thermal heating of heating coil for sterilization during humidification. The power consumption and $CO_2$ emission in the stage of use can be reduced to 1/4 and 1/3 at the highest estimate through improvement of sterilization method, respectively. We suggested the replacement of conventional thermal heating coil by ultra violet light-emitting diodes (UV-LED) for sterilization and then presented the experimental results on the sterilization effects of UV-LEDs.

• Journal of Ceramic Processing Research
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• v.13 no.spc2
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• pp.295-299
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• 2012

We investigated the crystal and the optical properties of GaN-based blue light emitting diodes (LEDs) which were simultaneously grown on c-plane (0001) and semipolar (11-22) GaN templates by using metal-organic chemical vapor deposition (MOCVD). The X-ray rocking curves (XRCs) full width at half maximums (FWHMs) of c-plane (0001) and semipolar (11-22) GaN templates were 275 and 889 arcsec, respectively. In addition, high-resolution X-ray ω-2θ scan showed that satellite peaks of semipolar (11-22) InGaN quantum-wells (QWs) was weaker and broader than that of c-plane (0001) InGaN QWs, indicating that the interface quality of c-plane (0001) QWs was superior to that of semipolar (11-22) QWs. Photoluminescence (PL) and electroluminescence (EL) results showed that the emission intensity and the FWHMs of polar c-plane (0001) LED were much higher and narrower than those of semipolar (11-22) LED, respectively. From these results, we believed that relative poor crystal quality of semipolar (11-22) GaN template might give rise to the poor interfacial quality of QWs, resulting in lower output power than conventional c-plane (0001) GaN-based LEDs.

• Korean Journal of Plant Tissue Culture
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• v.27 no.1
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• pp.71-75
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• 2000

To clarify the possibility of plant production under red, green. blue, and red+blue using light emitting diodes (LEDs) and fluorescent lamps (control), the effects of light quality on the growth and morphogenesis of in vitro seedlings in Piatycodon grandiflorum were examined. The plantlets grown under the LEDs resulted in taller plants with greater stem than fluorescent lamps. The shortest shoot length, 3.8 cm, was observed in the control and the longest one, 13.4 cm, in the red light. But the shoot length was 5.6 cm under red LED with supplemental blue(red+blue light). This results indicate that red LED may be suitable, in proper combination with other wavelengths of light. The root length under red light was significantly smaller among the treatments. The plantlets grown under red+blue light had lower shoot dry weight, higher dry matter than other lights-grown plantlets. Among the various growth parameters measered, there was an indication that leaf area was controlled by the LEDs. Leaf area of a plantlets developing under green light was about 2.4 times wider than that of plantlets grown under red LED (10.1 $\textrm{cm}^2$ in area). The dry matter rate per plantlet among the treatments was greater in plantlets grown under the red/blue LEDs in comparison with that grown under other LEDs. Chlorophyll contents in plantlets grown under the red, green, blue and red/blue LEDs were 2%, 7% 20% and 10% lower, respectively, than those in plant grown under fluorescent lamps.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.11 no.6
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• pp.175-182
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• 2012

Light characteristics of the monochromatic red(R), blue(B), green(G) and white(W) and the mixed LED (B-R LED) were investigated by light control a Spectrometer-MMS1 and an illuminometer. The power consumption of each LED was 1W and R LED has five wavelength bands(600nm, 640nm, 660nm, 680nm, 750nm). The light intensity of each LED was changed in a range 10~100%. As a results, the wavelength and the spectrum distribution of R LED increase with increasing light intensity but the wavelength of B, G, W LED decreases. It was found that illumination of each mononochromatic and B-R LED increases linearly with increasing light intensity. It was confirmed that the illumination intensity of R-B light has greater values than those obtained by monochromatic light at the same conditions.

• Journal of Applied Biological Chemistry
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• v.58 no.2
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• pp.101-104
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• 2015

To evaluate four different light-emitting diodes (LEDs) as potential attractants for Tyrophagus putrescentiae adults, attractiveness of blue (470 nm), green (520 nm), yellow (590 nm), and red (625 nm) LEDs were investigated at 20, 40, and 60 lx luminance intensity in LED-equipped Y-maze chamber and compared with the response to black light bulb (BLB), which is used in commercial traps. The BLB, the blue LED, the green LED, the yellow LED, and the red LED did not show the attractive to T. putrescentiae adults. These results suggested that four LEDs tested could not be used for environment-friendly control of T. putrescentiae adults.

• Korean Journal of Materials Research
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• v.22 no.11
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• pp.636-641
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• 2012

In this study, we have investigated highly efficient nanoscale surface corrugated light emitting diodes (LEDs) for the enhancement of light extraction efficiency (LEE) of nitride semiconductor LEDs. Nanoscale indium tin oxide (ITO) surface corrugations are fabricated by using the conformal nanoimprint technique; it was possible to observe an enhancement of LEE for the ITO surface corrugated LEDs. By incorporating this novel method, we determined that the total output power of the surface corrugated LEDs were enhanced by 45.6% for patterned sapphire substrate LEDs and by 41.9% for flat c-plane substrate LEDs. The enhancement of LEE through nanoscale surface corrugations was studied using 3-dimensional Finite Different Time Domain (FDTD) calculation. From the FDTD calculations, we were able to separate the light extraction from the top and bottom sides of device. This process revealed that light extraction from the top and bottom sides of a device strongly depends on the substrate and the surface corrugation. We found that enhanced LEE could be understood through the mechanism of enhanced light transmission due to refractive index matching and the increase of light scattering from the corrugated surface. LEE calculations for the encapsulated LEDs devices also revealed that low LEE enhancement is expected after encapsulation due to the reduction of the refractive index contrast.

• Journal of Fashion Business
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• v.25 no.1
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• pp.133-149
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• 2021

This study presents a new fashion wearable product, a classical music stage costume design, using an Arduino LilyPad that can control light-emitting diodes(LEDs) and a sound sensor that can set an environmental range of LED light. As a theoretical background, LED fashion design research and stage costume design research status were reviewed, and Arduino LilyPads, sensors, LEDs, and batteries required for LED stage costume production were investigated. Based on prior research, the LED stage costume design for the soprano stage was presented in a three-step process of design planning, development, and production, and an actual prototype was produced. This process produced meaningful information and materials for making clothes with the added function of a wearable computer. In particular, fashion designers or fashion majors can easily access the Arduino LillyPad and use not only LEDs, but other light emitting materials. It is expected that it will be used as a basic material for the use of the Arduino LillyPad that can develop new creations that have been utilized.