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The spectral characteristics of visual pigments are a major determinant in eliciting a response to light. To study the absorption maximum of the photoreceptors and their sensitivity to light in fish, rod outer segments (ROS) and cone cells were purified from the rock bream Oplegnathus fasciatus adapted to the dark. Ultraviolet/visible spectroscopic analyses of the ROS in the dark and its difference spectra indicated an absorption maximum of the visual pigment at ~ 500 nm, and each eye of 1-year-old rock bream contained at least 1.2 nmol of rhodopsin-like visual pigments. Microspectrophotometric analysis of the cone cell outer segments led to identification of three visual pigments with individual absorption maxima at 425, 520, and 585 nm. Monochromatic light-emitting diode (LED) modules with different wavelengths (violet 405 nm, blue 465 nm, cyan 505 nm, green 530 nm, amber 590 nm, and red 655 nm) were constructed to examine the spectral sensitivity and photoresponse in association with the absorption maximum of the photoreceptor. Analysis of chromophore decay upon illumination with each LED at low (27 μmol/m2/s) and high (343 μmol/m2/s) intensities showed the highest sensitivity of the photoreceptor upon illumination with the 505-nm cyan LED, followed by LEDs with wavelengths of 530 nm > 465 nm > 405 nm > 590 nm > 655 nm. Photoresponse analysis of the fish using a video tracking system, in the dark and upon illumination, also showed faster movement of fish with illumination with the cyan LED followed by in the order of green ≈ blue > violet > amber > red. These results indicated that a light with a wavelength closer to the absorption maximum of rhodopsin was more effective in eliciting a response to the light.

Green-yellow single crystal Lu 3 Al 5 O 12 :Ce 3+ (LuAG:Ce) as a color conversion phosphor for high-power laser lighting was grown through a floating zone method by an image furnace. It showed an excellent thermal stability, a lower quantum efficiency (QE), and a broader photoluminescence excitation (PLE) spectrum compared with the polycrystalline powder phosphor. The thermal stability was explained by a decrease of intrinsic defects and a less phonon generation at high temperature, confirmed by PLE spectra and temperature-dependent Raman spectra, respectively. To evaluate its feasibility for high-power laser lighting, the single crystal LuAG:Ce was applied to a 5 W blue laser diode with a remote-phosphor structure, and thus it reached a lower equilibrium temperature at 62 °C after 40 min operating in comparison with the polycrystalline powder phosphor (95 °C). Thus, the single crystal LuAG:Ce phosphor can achieve the extremely stable light emission without an efficiency loss under the high-power density of blue laser diode.

An inorganic-organic hybrid junction has been fabricated by spin coating the p-type poly(3- hexylthiophene-2,5-diyl)(P3HT) and poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonate) (PEDOT: PSS) on an n-type GaN layer. The GaN layer was formed on Al2O3 by metal organic chemical vapor deposition(MOCVD) method. To investigate the effects of P3HT concentration on the electrical properties, we changed P3HT solution concentration and speed of spin coater. The currentvoltage (I-V ) characteristic of Au/PEDOT:PSS/P3HT/n-GaN shows rectifying behavior. The I-V characteristic was examined in the frame work of the thermionic emission model. The most proper rectifying behavior was obtained for 0.6 wt% and thickness below 65 nm of P3HT used diode. We expect that such hybrid structures, suitably developed, might be enable the fabrication of highquality electronic and optoelectronic devices.

A Au nanomembrane is utilized as a hydroxyl ion channel to develop negative and positive-tone micro/nanolithography. Less than 50 nm thick Au films, that is, Au nanomembranes, have nanopores through which ions can pass. Micro- and nanostructures can be fabricated by using an Au nanomembrane-deposited Al layer with KOH solution loading on it. Hydroxyl ions diffuse over Au nanomembranes to react with an underneath Al layer. Depending on the pH of the fabrication process, which is governed by the volume of KOH solution loaded onto an Au nanomembrane-deposited Al layer, protruded aluminum hydroxide structures (positive tone lithography) or micro/nanotunnels (negative tone lithography) are able to be obtained. A flexible THz photonic structure and microfluidic channels have been demonstrated as possible applications of these structures.

We report on crystallographic analyses of one-dimensional GaN nanoneedles grown on a n-GaN epilayer by using hydride vapor phase epitaxy. The nanoneedles were grown with a HCl:NH3 gas flow ratio of 1:38 at 600 °C. The growth time of the GaN nanoneedles affected their morphologies. As time progressed, GaN dots nucleated and then evolved as nanoneedles. The vertical growth rate of GaN nanoneedles was higher than the lateral growth rate under optimized growth conditions. X-ray pole figure measurements were carried out using a four-axis diffractometer. For the sample grown for 20 min, we obtained discrete patterns with six strong dots and weak dough-nut and cotton swab patterns, indicating that most of the nanoneedles were grown ideally, but partially, in the x-y plane with an azimuthal rotation angle ϕ = 15 ~ 45° rotated to the substrate, and a few GaN nanoneedles were tilted by ±4° or by more than 32° from the vertical c-axis.

Solid solubility limit of Ce 3+ ions into Lu-based garnet, Lu 3(1− x ) Ce 3 x Al 5 O 12 , was determined as below 6.7 mol% (3 x x ≥0.2 mol), Lu 3(1− x ) Ce 3 x Al 5 O 12 phosphors showed the significant redshift to the yellow spectral region without Y 3+ and Gd 3+ ions. The redshift was explained in terms of the local compressive strain at the Ce 3+ sites. The optimized sample (3 x =0.4 mol) had a dominant emission wavelength of 548 nm, color coordinate of CIE x =0.421, CIE y =0.548, quantum efficiency of 80%, absorbance of 91%, lumen maintenance of 90% and high color stability at 473 K under 450 nm excitation wavelength, suggesting substitutability for the commercial yellow (Y, Gd) 3 (Al, Ga) 5 O 12 :Ce 3+ phosphor. The measured decay times at higher Ce 3+ concentration are significantly shortened at higher temperature than that of those at lower Ce 3+ concentration. The yellow Lu 2.6 Ce 0.4 Al 5 O 12 and a commercial red (Sr, Ca)AlSiN 3 :Eu 2+ phosphor were applied to the pc-WLED, it gave an excellent luminous efficiency (138 lm/W) with a slightly lower color rendering index (Ra=76.4) under correlated color temperature of 6500 K compared to those of the (Y, Gd) 3 (Al, Ga) 5 O 12 :Ce 3+ -based one (136 lm/W, Ra=78.7). Especially, the quantities of the used phosphors were significantly decreased by 20% for the yellow LuAG:Ce and by 40% for the red (Sr, Ca)AlSiN 3 :Eu 2+ . Thus, the Y/Gd−free pure LuAG:Ce yellow phosphors can be used as alternative to the commercial yellow YAG:Ce phosphor.

To study the absorption characteristics of rhodopsin, a dim-light photoreceptor, in chub mackerel (Scomber japonicus) and the relationship between light wavelengths on the photoresponse, the rod opsin gene was cloned into an expression vector, pMT4. Recombinant opsin was transiently expressed in COS-1 cells and reconstituted with 11-cis-retinal. Cells containing the regenerated rhodopsin were solubilized and subjected to UV/Vis spectroscopic analysis in the dark and upon illumination. Difference spectra from the lysates indicated an absorption maximum of mackerel rhodopsin around 500 nm. Four types of light-emitting diode (LED) modules with different wavelengths (red, peak 627 nm; cyan, 505 nm; blue, 442 nm; white, 447 + 560 nm) were constructed to examine their effects on the photoresponse in chub mackerel. Behavioral responses of the mackerels, including speed and frequencies acclimated in the dark and upon LED illumination, were analyzed using an underwater acoustic camera. Compared to an average speed of 22.25 ± 1.57 cm/s of mackerel movement in the dark, speed increased to 22.97 ± 0.29, 24.66 ± 1.06, 26.28 ± 2.28, and 25.19 ± 1.91 cm/s upon exposure to red, blue, cyan, and white LEDs, respectively. There were increases of 103.48 ± 1.58, 109.37 ± 5.29, 118.48 ± 10.82, and 109.43 ± 3.92 %, respectively, in the relative speed of the fishes upon illumination with red, blue, cyan, and white LEDs compared with that in the dark (set at 100 %). Similar rate of wavelength-dependent responses was observed in a frequency analysis. These results indicate that an LED emitting a peak wavelength close to an absorption maximum of rhodopsin is more effective at eliciting a response to light.

Yellow Y3Al5O12:Ce3+ single crystal phosphor was grown through a floating zone method. It showed a broader blue excitation and yellow emission spectra with lower quantum efficiency due to large internal reflections but higher thermal stability due to high thermal conductivity than the conventional powder. With pulverizing the as-grown single crystal down to micron powder, its quantum efficiency was enhanced, while its lumen maintenance at high temperature (200 °C) was reduced due to a generation of more phonons, confirmed by temperature-dependent Raman spectra. The as-grown and pulverized single crystal samples were applied to a high-power blue laser diode, and thus they gave an excellent luminescence feasibility to a high-power lighting source.

A carbon microsphere of a core-shell type was grown by using a new method of mixed-source hydride vapor phase epitaxy (HVPE). The surface and the cross section of the carbon microsphere grown by using the new method were observed by using scanning electron microscopy (SEM). The characteristics of the carbon microsphere were investigated by using X-ray photoelectron spectroscopy (XPS) and high-resolution transmission electron microscopy (HR-TEM). From these measurements, the diameters of the carbon spheres were about a few hundred micrometers. Furthermore, we showed that carbon microspheres of the core-shell type could be grown successfully by using a mixed-source HVPE method and that they had larger sizes than those grown by using existing methods. This mixed-source HVPE method is proposed as a new method for making carbon microspheres.

In this paper, we propose the LED(Light-Emitting-Diode) emergency lighting in a tunnel by using the thermoelectric devices. To achieve high generated power, thermoelectric device should be have high Seebeck coefficient and small contact area. Also, we reveal that a moderate heatsink required for high generated power. From the waste heat of LED tunnel lighting module (25W), the generated power was 0.062W by thermoelectric device, and it could illuminate for 1hour after charge the battery of emergency lighting during about 101hours.

A thick AlN epilayer is grown directly on a c-plane sapphire substrate by using the hydride vapor phase epitaxy (HVPE) method with a small quantity of Al. The new type (RF + hot-wall) flow HVPE reactor used in the AlN epilayer growth is custommade. The growth temperatures of the source and the growth zones are set at 950 °C and 1145 °C, respectively. The characteristics of the AlN layer grown on a sapphire substrate are investigated by using energy dispersive spectroscopy (EDS), X-ray diffraction (XRD) and Fourier-transform infrared (FTIR) spectroscopy. The value of the full width at half maximum (FWHM) for the (002) peak from the AlN layer on the sapphire substrate is observed at 790 arcsec. From the small value of the FWHM, the AlN layer seems to be a well-arranged plane with a uniform (002) growth direction on a sapphire substrate.

In this study, we examined differences among the gonadotropin-inhibitory hormone (GnIH), kisspeptin 1 (Kiss1), Kiss 1 receptor (G-protein-coupled receptor 54; GPR54), melatonin receptor 1 (MT1), and melatonin levels in brain cells of goldfish Carassius auratus exposed to white fluorescent light and three light-emitting diode (LED) wavelength and melatonin treatments in the culture medium. In the green and blue LED treatment groups, GnIH and MT1 mRNA expression levels were significantly lower than in the other groups; conversely, levels significantly increased in the melatonin treatment groups. Additionally, expression levels of Kiss1 and its receptor, GPR54, in the white fluorescent and red LED light groups were significantly lower than the other groups, but levels also significantly decreased in the melatonin treatment groups. These results suggest that white fluorescent and red wavelengths downregulate the production of neurohormones in the brains of C. auratus and thus may inhibit sexual maturation in ...

Gallium nitride (GaN) nanoneedles were synthesized by using the hydride vapor phase epitaxy method at various growth temperatures and times under a HCl:NH3 flow ratio of 1:38. The morphology of GaN nanostructures varied according to the growth temperatures, and nanoneedles were formed at 640°C temperature zone. Further, their heights and diameters increased with increasing growth time whereas the stems of the nanoneedles coalesced. X-ray diffraction patterns showed that the GaN nanoneedles were orientated along the [0001] direction and underwent biaxial compressive stress. Also, the Raman spectra exhibited the smallest compressive strain in the sample grown for 60 min compared to the other samples.

Bismuth oxychloride (BiOCl) was synthesized by a simple combustion method. The structures, morphologies, absorbance, optical, and photocatalytic properties of the samples were studied by X-ray powder diffraction, scanning electron microscopy, transmission electron microscopy, ultraviolet–visible spectrophotometry, and photoluminescence. The experimental results show that BiOCl microsheet with high percentage of exposed {001} facets was obtained. It is interesting to note that the thickness of BiOCl sheets, in other words, the percentage of exposed {001} facets can be modulated through changing the added amount of ammonium chloride. The sample with the thinnest BiOCl sheets shows the best photodegradation performance of Rhodamine B under ultraviolet light irradiation, which can be attributed to the cooperative effect between the high percentage of exposed {001} facets and high-specific surface area. Moreover, the corresponding influencing mechanism on the percentage of exposed {001} facets of BiOCl was discussed.

The purpose of this paper is to analyze thermal characteristics of the heat sinks to maximize the thermal diffusivity for LED floodlight. The 2 kind of samples were prepared by vapor chamber manufacturing technology using the heat pipe principle. It was analyzed the maximum temperature reduction effect and the thermal diffusion from the heat source depending on the types of chambers with 3 kind of working fluids. As a result, it was confirmed that thermal conductivity 23% increased, GVC-R type than IVC-R type.

Ag/ZnO nanocomposites were synthesized by a rapid one-step microwave-assisted combustion method. The as-synthesized samples were characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy, X-ray photoelectron spectroscopy, photoluminescence and ultraviolet–visible spectrophotometry. XRD results showed that hexagonal ZnO and cubic Ag were obtained. Ag nanoparticles were chemically attached on the surface of ZnO. The decrease in the energy band gap of Ag/ZnO nanocomposites and the photoluminescence quenching were observed while the Ag content was increased. Furthermore, the introduction of Ag nanoparticles leads to significantly improved photocatalytic activities in the case of ultraviolet irradiation, but in the case of visible-light irradiation opposite results were obtained. The corresponding mechanism was discussed in detail.

Magnetic Ag/NiFe2O4 (ANFO) photocatalysts were synthesized by a one-step combustion method. The structures, morphologies, optical, magnetic, and visible-light photocatalytic properties of as-prepared ANFOs were characterized. Experimental results showed that cubic spinel NiFe2O4 and face-centered-cubic Ag were exclusively obtained. With increasing Ag content, red shift of the absorption edge and photoluminescence quenching were observed. The magnetic properties of ANFOs ensure the magnetic separation by using a magnet. ANFO with a mole ratio of Ag to NiFe2O4 of 0.04 shows the best visible-light photodegradation performance of methylene blue, which can be ascribed to the decrease in the energy band gap and the efficient transfer of photo-generated electrons from NiFe2O4 to Ag nanoparticles. Moreover, no obvious deterioration was observed the cycle photodegradation experiments.

In this paper, we develop a explosion-proof LED lighting (Ex circuit) circuit of Explosion-proof LED Signal Lamp (Ex LSL) to utilize the core module of the explosion-proof Local Control System (Ex LCS) for offshore plant applications. And then analyzed its electrical, optical and thermal characteristics. Ex circuit was applied input voltage from AC/DC(12~254) V. In this experiments, stable light-on characteristics were confirmed by eyes for the every input voltages with min. 78,462 and max. 517,975  of luminance. also Output current and output luminance was made proportional. Because the measured maximum surface temperature of Ex circuit was 54.23°C at AC 48 V, Ex circuit was rated with T6 of temperature class. Finally, Ex circuit was shown stable light on characteristics under the–50°C and 60°C during 12 hours of test period.

The heat dissipation conditions of high-power 5 watt LEDs-based searchlight modules were optimized with varying LED bar`shape, materials, and ambient temperature. The LED junction temperature was estimated by using Computational Fluid Dynamics simulation. The optimal heat dissipation conditions were found as follows; LED bar` shape: L

Department of LED Fusion Engineering, Pukyong National University, Busan 608-739, Korea(Received June 5, 2014; Revised July 3, 2014; Accepted July 4, 2014)Abstract: Korea Expressway Corporation established standard of LED lighting fixture in Dec. 2013. To raise compatibility, the standard requires a fixed form and it is applied to street lights and tunnel lights, etc. Because streetlight has different circumstance condition from tunnel light that is down light and exposed to constant wind velocity over height of 8 meters, in case of LED module which has the same shape, characteristic of radiant heat can be different. In this paper, we designed 25 [W] LED Module that is designated by standard of Korea Expressway Corporation and analyzed characteristics of radiant heat about natural convection and forced convection. It is dropped 10.12[℃] that max temperature is decreased by increasing 20 mm of bended height of heatsink at the condition of natural convection. Radiant heat characteristic of bended height 35 mm became 78.08[℃] at the condition of natural convection, 55.30[℃] at the condition of forced convection so that 22.78[℃] is decreased that is 29.1[%] decrease. Bended height 55mm became 67.96[℃] at the condition of natural convection, 48.04[℃] at the condition of forced convection so that 19.92[℃] is decreased that is 29.3% decrease.Keywords: LED module, Heatsink, Standard, Forced convection, Natural convection

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In this paper, we report the synthesis and photoluminescence (PL) properties of β′-Gd 2 Mo 3 O 12 doped with Eu 3+ ions. The relationship between Eu 3+ luminescence versus concentration and temperature is discussed. In order to investigate the mechanism of concentration quenching, luminescence decay curves are measured and the Inokuti–Hirayama model is used to analyze them. The activation energy for the thermal quenching is estimated by the Arrhenius fitting. The emission spectrum of β′-Gd 2 Mo 3 O 12 exhibits the strongest emission peak at 614.5 nm due to electric–dipole transition. The excitation spectrum shows several sets of lines in the range of 350–425 nm which are associated with the typical intra-configurational 4f 6 transitions of Eu 3+ . The spectral positions of these lines match well with the emission spectra of near-UV LEDs, which makes the phosphor find a potential application for white light-emitting-diodes.

In this paper, tried to find out the proper luminous intensity distribution for the cabin with low-level height by analyzing the changing tendency of discomfort glare according to luminous intensity distribution of marine indoor luminaires using Unified Glare Rating(UGR). First, we analyzed UGR of the indoor luminaires in the existing cabin, and then evaluated influence on luminous intensity distributions of marine indoor luminaire. The results showed that cos θ distribution got almost low UGR results regardless of height and UGR 16.5 in cabin height of 2m. However, Gaussian distribution with the same beam angle showed that UGR results consistently increased by getting lower height and UGR 20.7 in the same height. In conclusion, the cos θ distribution in consideration of luminous intensity on the direction of observer's eye was appropriate for general cabin indoor luminaires because it decreased UGR in the low-level height.

A blue-emitting phosphor Ca3Mg3(PO4)4:Eu2+ peaking at 450 nm was synthesized by a solid state reaction. The XRD patterns, luminescence properties, decay curves of samples as well as their thermal quenching and comparing the luminescence properties with that of commercial material were investigated. At 20 K, the emission spectrum exhibiting two distinct bands peaking at 437 and 473 nm with a shoulder peak at 510 nm can be attributed to the overlap of Eu(I), Eu(II) and Eu(III) emission bands. At 423 K the PL intensity decreases to 80% of the value at room temperature, and the emission wavelength shifts toward high energy. The derived activation energy indicates that the lowest energy level of the Eu2+ 4f65d1 state is well isolated from the host lattice conduction band. The PL spectra and chromaticity coordinates are close to those of BAM. Ca3Mg3(PO4)4:Eu2+ could be a potential candidate for near-UV excited white LEDs.