• Journal of the Korean Institute of Telematics and Electronics
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• v.25 no.7
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• pp.791-798
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• 1988

Films of Cr, Cu, and Al were deposited by the evaporation technique at the high vacuum level-high evaporation rate and the low vacuum level-low evaporation rate. We measured sheet resistance and light transmittance, and observed microstructure and diffraction pattern by TEM, and investigated oxygen content in thin film by AES. We discussed the relations among microstructure, sheet resistance, and light transmittance with AES data. We found that the films deposited at the high vacuum level-high evaporation rate have small oxygen content in thin film comparing to the films deposited at the low vacuum level-low vacuum level-low evaporation rate, and that the films having crystalline structure and larger grain size were formed in the case of the high vacuum level-high evaporation rate and they showed lower sheet resistance and lower light transmittance.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2018.10a
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• pp.480-483
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• 2018

In this paper, we study the interference canceling and image sensing processing technology of multiple light sources for high speed transmission in CMOS sensor based visible light communication system. To improve transmission capacity in optical camera communications via image sensors, different data must be transmitted simultaneously from each LED. However, multiple LED light source environments for high-speed transmission can cause interference between adjacent LEDs. In this case, since the visible light communication system generally uses intensity modulation, when a plurality of LEDs transmit data at the same time, it is difficult to accurately detect the respective LEDs due to the light scattering interference of the adjacent LEDs. In order to solve this problem, the ON / OFF state of many LEDs of the light source is accurately recognized by using a dual CMOS sensor, and the spectral estimation technique and the pixel image signal processing technique of each LED are proposed. This technique can accurately recognize multiple LED pixels and improve the total average bit error rate and throughput of a MISO-VLC system.

• Journal of Photoscience
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• v.9 no.2
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• pp.326-328
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• 2002

In many plant cells, the positions of chloroplasts change in response to changes in light conditions. In the epidermal cells of the aquatic angiosperm Vallisneria gigantea, the avoidance response of chloroplasts is induced specifically by irradiation with blue light of high intensity. Possible roles of actin cytoskeleton in the blue-light-induced avoidance response of chloroplasts were investigated by partial irradiation and phalloidin staining. We showed that the blue-light-dependent redistribution of chloroplasts was induced only in the limited area, where exposed to blue light, even in individual cells. In addition. in the exposed area, the configuration of actin filaments strikingly changed compared with that before the irradiation. Short and thick bundles of actin filaments surrounding the chloroplasts changed to much longer and thinner bundles with a more stretched array. In contrast, in the unexposed area, neither the distribution of chloroplasts nor the configuration of actin filaments exhibited any changes. Cytochalasin D and latrunculin B inhibited the avoidance response of chloroplasts concomitantly with the fragmentation of actin filaments. These results indicate that the reorganization of actin filaments plays a crucial role in the induction of avoidance response of chloroplasts.

• Journal of Microbiology and Biotechnology
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• v.14 no.3
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• pp.442-449
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• 2004

Improving the light utilization efficiency of photosynthetic cells in photobioreactors (PBRs) is a major topic in algal biotechnology. Accordingly, in the current study we investigated the effect and suitability of photosynthetic pigment reduction for improving light utilization efficiency. The light-harvesting complex II (LH-II) genes of Rhodobacter sphaeroides were removed to construct a mutant strain with less pigment content. The mutant strain exhibited a slower growth rate than the wild-type under a low light intensity, while the mutant grew faster under a high light intensity. In addition, the specific absorption coefficient was lower in the mutant due to its reduced pigment content, thus it seemed that light penetrated deeper into its culture broth. However, the distance (light penetration depth) from the surface of the PBR to the compensation point did not increase, due to an increase in the compensation irradiance of the mutant strain. Experimental data showed that a reduced photosynthetic pigment content, which lessened the photoinhibition under high-intensity light, helped the volumetric productivity of photosynthetic microorganisms.

• Ocean and Polar Research
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• v.39 no.2
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• pp.107-114
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• 2017

In this study, we investigated the effects of light spectra on physiology stress and DNA damage in juvenile rock bream (Oplegnathus fasciatus) using light-emitting diodes (LEDs; green, 520 nm; red, 630 nm) at two intensities (0.25 and $0.5W/m^2$ ) with application of thermal stress (25 and $30^{\circ}C$). We measured the mRNA expression of heat shock protein 70 (HSP70) and the levels of plasma cortisol, glucose, aspartate aminotransferase (AspAT), and alanine aminotransferase (AlaAT). Additionally, DNA damage was measured using comet assays. Our findings showed that HSP70 mRNA expression and plasma cortisol, glucose, AspAT, and AlaAT levels were significantly higher after exposure to high temperatures and were significantly lower after exposure to green LED light. Thus, although high water temperatures induced stress in juvenile rock bream, green LED light inhibited stress. In particular, green LED light reduced stress and DNA damage to a greater degree than other light sources.

• ALGAE
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• v.28 no.4
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• pp.355-363
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• 2013

The coralline alga, Corallina officinalis, is a widely distributed intertidal species in temperate coastal regions. It is usually exposed to high fluctuations of light intensity, light quality, temperature, and desiccation, all of which affect the temporal and spatial distribution as well as the morphology and the metabolism of this alga. In laboratory experiments we examined the effects of different light intensities (50, 100, and 200 ${\mu}mol$ photons $m^{-2}s^{-1}$) on photosynthesis, calcification, photosynthetic pigment contents (chlorophyll a and carotenoids), and growth rate of C. officinalis to clarify its photoacclimation strategies. Net photosynthesis, calcification and dissolution rates based on weight were not sensitive to irradiance. Although, photosynthesis and calcification did not clearly respond to light intensity, photosynthetic pigment contents were significantly lower at higher light intensities. In addition, higher irradiances induced significant enhancement of gross photosynthesis based on chlorophyll a. As a result, the specific growth rate was significantly stimulated by high light intensity. Our results suggest that photoacclimation of C. officinalis to different light conditions may be regulated to optimize growth.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.34 no.5
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• pp.371-381
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• 2021

A machine vision inspection system consists of a camera, optics, illumination, and image acquisition system. Especially a scanning system has to be made to measure a large inspection area. Therefore, a machine vision line scan camera needs a line scan light source. A line scan light source should have a high light intensity and a uniform intensity distribution. In this paper, an offset calibration and slope calibration methods are introduced to obtain a uniform light intensity profile. Offset calibration method is to remove the deviation of light intensity among channels through adding intensity difference. Slope calibration is to remove variation of light intensity slope according to the control step among channels through multiplying slope difference. We can obtain an improved light intensity profile through applying offset and slope calibration simultaneously. The proposed method can help to obtain clearer image with a high precision in a machine vision inspection system.

• Journal of the Semiconductor & Display Technology
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• v.21 no.3
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• pp.39-44
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• 2022

The light extraction technology for improving the light efficiency of OLEDs is the core technology for extracting the light inside the OLEDs to the outside. This study demonstrates a simple method to generate random nanostructures (RNSs) containing high refractive index nanoparticles to improve light extraction and viewing angle characteristics. A simple dry low-temperature process makes the nanostructured scattering layer on the polymer resin widely used in the industry. The scattering layer has the shape of randomly distributed nanorods. To control optical properties, we focused on changing the shape and density of RNSs and adjusting the concentration of high refractive index nanoparticles. As a result, the film of the present invention exhibits a perpendicular transmittance of 85% at a wavelength of 550 nm. This film was used as a scattering layer to reduce substrate mode loss and improve EL efficiency in OLEDs.

• Journal of Broadcast Engineering
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• v.14 no.4
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• pp.475-487
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• 2009

We propose a visible light road-to-vehicle communication system at intersection as one of ITS technique. In this system, the communication between vehicle and a LED traffic light is approached using LED traffic light as a transmitter, and on-vehicle high-speed camera as a receiver. The LEDs in the transmitter are emitted in 500Hz and those emitting LEDs are captured by a high-speed camera for making communication. Here, the luminance value of each LED in the transmitter should be found for consecutive frames to achieve effective communication. For this purpose, first the transmitter should be identified, then it should be tracked for consecutive frames while the vehicle is moving, by processing the images from the high-speed camera. In our previous work, the transmitter was identified by getting the subtraction of two consecutive frames. In this paper, we mainly introduce an algorithm to track the identified transmitter in consecutive frames. Experimental results using appropriate images showed the effectiveness of the proposal.

• Korean Journal of Veterinary Research
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• v.55 no.2
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• pp.111-116
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• 2015

In the present study, the effects of different photoperiods on stress, immunity, and hematological parameters in ICR mice were evaluated. Fifty male ICR mice 7 weeks old (body weight, $27.3{\pm}2.5g$) were divided into five groups: DP-0 (0/24-h light/dark cycle), DP-6 (6/18-h light/dark cycle), DP-12 (12/12-h light/dark cycle), DP-18 (18/6-h light/dark cycle), and DP-24 (24/0-h light/dark cycle). During the experimental period, no significant differences in body weight or feed intake were observed between the groups. Hematological analysis revealed that white blood cell, red blood cell, and hemoglobin values for the DP-0 group were significantly different compared to those of the other groups. After 28 days, no significant difference in serum cortisol concentration was observed among the groups, but serum cortisol levels increased in a light exposure-dependent manner. Total serum immunoglobulin G (IgG) concentrations of the DP-0 and PD-6 groups were significantly increased compared to those of the other groups (p < 0.05), and serum total IgG levels decreased in a light exposure-dependent manner. Results of the present study indicated that various photoperiods affect hematological parameters and total serum IgG levels in ICR mice while having no significant effects on body weight, feed intake, or cortisol levels.