Visibility Improvement in Expressway Tunnels by Optimizing the Color Temperature and Light Distribution of the Pulse-operated LED Luminaires

Constant light power operation of an ultraviolet (UV) LED based on portable low-cost instrumentation and a monolithically integrated monitoring photodiode (MPD) has been reported for the first time. UV light irradiation has become one of the essential measures for disinfection and sterilization. Monitoring and maintaining a specified light power level is important to meet the criteria of sterilization. We built a module composed of a monolithically integrated UV LED and MPD, a transimpedance amplifier, an Arduino Uno card, a digital-to-analog converter and a Bluetooth transceiver. An Android App that we wrote remotely controlled the UV LED module via Bluetooth. The Arduino Uno card was programmed to receive demands from the smartphone, sent a driving voltage to the LED and returned the present MPD voltage to the smartphone. A feedback loop was used to adjust the LED voltage for maintaining a constant light output. We successfully demonstrated the functioning of remote control of the App, and the resultant UV LED measured power remained the same as the setting power. This setup can also be applied to visible or white LEDs for controlling/maintaining mixed light’s chromaticity coordinates or color temperature. With such controlling and internet capability, custom profiling and maintenance of precision lighting remotely would be possible.

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Analysis on High-Power Seaport LED Luminaire with Uniform Light Distribution Based on Optimized Lens and Heatsink

Applied Sciences ◽

10.3390/app11094035 ◽

2021 ◽

Vol 11 (9) ◽

pp. 4035

Author(s):

Jinsheon Kim ◽

Jeungmo Kang ◽

Woojin Jang

Keyword(s):

Light Source ◽

High Power ◽

Heat Dissipation ◽

Light Emitting Diode ◽

Light Distribution ◽

Light Sources ◽

Led Light ◽

High Power Led ◽

Distribution Requirement ◽

Lighting Application

In the case of light-emitting diode (LED) seaport luminaires, they should be designed in consideration of glare, average illuminance, and overall uniformity. Although it is possible to implement light distribution through auxiliary devices such as reflectors, it means increasing the weight and size of the luminaire, which reduces the feasibility. Considering the special environment of seaport luminaires, which are installed at a height of 30 m or more, it is necessary to reduce the weight of the device, facilitate replacement, and secure a light source with a long life. In this paper, an optimized lens design was investigated to provide uniform light distribution to meet the requirement in the seaport lighting application. Four types of lens were designed and fabricated to verify the uniform light distribution requirement for the seaport lighting application. Using numerical analysis, we optimized the lens that provides the required minimum overall uniformity for the seaport lighting application. A theoretical analysis for the heatsink structure and shape were conducted to reduce the heat from the high-power LED light sources up to 250 W. As a result of these analyses on the heat dissipation characteristics of the high-power LED light source used in the LED seaport luminaire, the heatsink with hexagonal-shape fins shows the best heat dissipation effect. Finally, a prototype LED seaport luminaire with an optimized lens and heat sink was fabricated and tested in a real seaport environment. The light distribution characteristics of this prototype LED seaport luminaire were compared with a commercial high-pressure sodium luminaire and metal halide luminaire.

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Full-visible-spectrum emission with high color rendering index and low correlated color temperature enabled by a single-phased phosphor of α-Sr2V1.98P0.02O7: 0.5% Eu3+

Materials Research Bulletin ◽

10.1016/j.materresbull.2021.111344 ◽

2021 ◽

pp. 111344

Author(s):

Yanzhen Yin ◽

Zhen Wang ◽

Maochen Zhu ◽

Yue Zhang ◽

Jianhong Li ◽

...

Keyword(s):

Visible Spectrum ◽

Color Temperature ◽

Color Rendering Index ◽

Color Rendering

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Tailoring diffraction-induced light distribution toward controllable fabrication of suspended C-MEMS

Optics Express ◽

10.1364/oe.20.017126 ◽

2012 ◽

Vol 20 (15) ◽

pp. 17126 ◽

Cited By ~ 9

Author(s):

Hu Long ◽

Shuang Xi ◽

Dan Liu ◽

Tielin Shi ◽

Qi Xia ◽

...

Keyword(s):

Light Distribution ◽

Controllable Fabrication

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A preliminary study on visibility improvement of turbid underwater images for dismantling of nuclear facilities

Annals of Nuclear Energy ◽

10.1016/j.anucene.2021.108207 ◽

2021 ◽

Vol 156 ◽

pp. 108207

Author(s):

Seung-Kyu Park ◽

Seong Yong Oh ◽

Jae Sung Shin ◽

Hyunmin Park ◽

Jonghwan Lee

Keyword(s):

Nuclear Facilities ◽

Preliminary Study ◽

Visibility Improvement

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The effects of short-term light exposure on subjective affect and comfort are dependent on the lighting time of day

Scientific Reports ◽

10.1038/s41598-021-81182-y ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

Lijun Chen ◽

Fang-Fang Yan ◽

Shuhan Fan ◽

Yifan Wu ◽

Jia Yang ◽

...

Keyword(s):

Significant Role ◽

Negative Correlation ◽

Significant Interaction ◽

Daily Life ◽

Light Exposure ◽

Time Of Day ◽

Color Temperature ◽

Subjective Feeling ◽

Short Term ◽

Illuminance Level

AbstractLight, one of the key environmental components for both life and work, played significant role in subjective feelings (e.g. affect and comfort), but the exact effects and mechanisms were still to be determined. The present study screened thirty healthy adults (13 females, 22.45 ± 3.26 years) and examined subjective affect and comfort under short-term white lights with different combination of correlated color temperature (CCT) and illuminance at different times of day (e.g. morning, afternoon, and evening). Our results showed a significant interaction between illuminance level and time-of-day on subjective comfort. Participants felt more comfortable under 50 lx and 100 lx instead of 500 lx in the evening, and more comfortable under 500 lx in the morning and afternoon. In addition, a positive correlation between illuminance and comfort in the morning and a negative correlation between them in the evening were found. No significant effect of CCT on any subjective feeling was revealed. Our results necessitate the consideration of time-of-day in understanding lighting effects and application of healthy lighting in daily life.

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Light Output, Thermal Properties, and Reliability of Using Glass Phosphors in WLED Packages

Coatings ◽

10.3390/coatings11020239 ◽

2021 ◽

Vol 11 (2) ◽

pp. 239

Author(s):

Chin-Chuan Huang ◽

Tsung-Han Weng ◽

Chun-Liang Lin ◽

Yan-Kuin Su

Keyword(s):

Thermal Properties ◽

Yttrium Aluminum Garnet ◽

Saturated Vapor ◽

Light Output ◽

Junction Temperature ◽

Color Temperature ◽

Light Emitting ◽

Chromaticity Coordinate ◽

White Light Emitting Diodes ◽

Color Rendering

White-light-emitting diodes (WLED) based on yttrium aluminum garnet (YAG) phosphors sintered with glass (PiG) and with silicone (PiS) are compared in terms of their light properties, temperature properties and reliability.The complete YAG phosphor was doped with an encapsulant traditional WLED (PiS WLED), and the WLED was covered with PiG (PiG WLED). PiG was made by sintering glass powder and YAG phosphor at the ratio of 87:13 (%), and the correlated color temperature (CCT) was 5564 K. The CCT of the PiG WLED with the YAG doping concentration of 8.5 wt.% approximated 5649 K. The initial light output of the PiG WLED was 6.4% lower than that of the PiS WLED. Under 1008 h and 350 mA aging, PiG WLED and PiS WLED’ light output, CCT and color rendering index variation rates were all within 1%. In the saturated vapor-pressure test, no sample exhibited red ink infiltration, light nor peeling between the encapsulant and the lead-frame. Compared with that of the PiS WLED, the junction temperature of the PiG WLED reduced from 88.4 °C to 81.3 °C. Thermal resistance dropped from 37.4 °C/W to 35.6 °C/W. The PiG WLED presented a better CIE (Commission Internationale de l’Eclairage) 1931 chromaticity coordinate (x,y) concentration and thermal properties than the PiS WLED.

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