• Journal of Ocean Engineering and Technology
• /
• v.34 no.6
• /
• pp.442-453
• /
• 2020

Underwater color images suffer from low visibility and color cast effects caused by light attenuation by water and floating particles. This study applied single image enhancement techniques to enhance the quality of underwater images and compared their performance with real underwater images taken in Korean waters. Dark channel prior (DCP), gradient transform, image fusion, and generative adversarial networks (GAN), such as cycleGAN and underwater GAN (UGAN), were considered for single image enhancement. Their performance was evaluated in terms of underwater image quality measure, underwater color image quality evaluation, gray-world assumption, and blur metric. The DCP saturated the underwater images to a specific greenish or bluish color tone and reduced the brightness of the background signal. The gradient transform method with two transmission maps were sensitive to the light source and highlighted the region exposed to light. Although image fusion enabled reasonable color correction, the object details were lost due to the last fusion step. CycleGAN corrected overall color tone relatively well but generated artifacts in the background. UGAN showed good visual quality and obtained the highest scores against all figures of merit (FOMs) by compensating for the colors and visibility compared to the other single enhancement methods.

• BMB Reports
• /
• v.56 no.9
• /
• pp.502-507
• /
• 2023

Photobiomodulation therapy has been proposed as a promising therapeutic approach for retinal degenerative diseases. However, its effect on the regenerative capacity in mammalian retina and its intracellular signalling mechanisms remain unknown. Here, we show that photobiomodulation with 670 nm light stimulates Müller glia cell cycle re-entry and dedifferentiation into a progenitor-like state in both the uninjured and injured retina. We also find that 670 nm light treatment inhibits the Hippo pathway, which is activated in Müller glia following NaIO₃-induced retinal injury. YAP, a major downstream effector of the Hippo signalling pathway was translocated into the nucleus of Müller glia along with YAP dephosphorylation in retina treated with 670 nm light. Deficiency of YAP attenuated Müller glia cell cycle re-entry and dedifferentiation. Our data reveal that the Hippo-YAP signalling pathway is associated with the photostimulatory effect on regenerative response in mammalian retina, and suggest a potential therapeutic strategy for retinal degenerative diseases.

• KSBB Journal
• /
• v.19 no.4
• /
• pp.257-262
• /
• 2004

Recently, there is a growing interest in microalgae and the use of microalgae focused on the production of various high value metabolite used in food, pharmaceuticals and cosmetics. The key limiting factor in high density algal cultivation is the light and algal growth is defined by light intensity and light penetration depth into the culture medium. The effect of light with various light paths, S/V ratios, light intensities, and 50% duty cycle on the growth of microalgae was examined to enhance microalgal biomass productivity and photosynthetic efficiency. We confirmed that the utilization of efficient light energy was obtained from 4 cm of diameter, 57.6% of S/V ratio, 62 ${\mu}$mol/㎡/s of light intensity.

• Journal of Advanced Marine Engineering and Technology
• /
• v.22 no.6
• /
• pp.816-826
• /
• 1998

The effects of rice bran oil on the characteristics of performance and exhaust emissions have been experimentally examined by a single cylinder four cycle direct injection water-cooled and agricultural diesel engine operating at several loads and speeds. The experiments are conducted with light oil blends of rice bran with light oil and rice bran oil as a fuel. The fuel injection timing if fixed to $22^{\circ}$ BTDC regardless of fuel type engine loads and speeds. Any oxygen is not included in light oil while the oxygen contents of 10.7% are included in rice bran oil. The lower calorific value of rice bran oil is less than light oil and the viscosity is very high compared with light oil. In pre-sent study it is found that these major differences of chemical and physical properties control the combustion parameters that affect the performance and exhaust emissions of diesel engines using a rice bran oil as fuels.

• Biomedical Science Letters
• /
• v.10 no.3
• /
• pp.275-283
• /
• 2004

The annual changes in testis weight and diameter of seminiferous tubules, and the seminiferous epithelium cycle of Tamias sibiricus were studied by light microscope. Testis weight and diameter of seminiferous tubule are significantly increased from January to July, and decreased rapidly to the size from August to December. Spermatogenesis occurs from January to July, and spermatocytogenesis are produced from August to December. The cycle of the seminiferous epithelium was divided into 12 stages during the development of spermatids as a changes of the nucleus and acrosomal structure, presence and/or absence of residual body, appearance and/or absence of sperm tail and meiotic figure and spermiation. The dark type spermatogonia (Ad) are appeared in all stages (I ~ XII), and the spermatids of step 10 are observed at I, II, X and XII stages. The spermatids of step 11 are appeared in III and IV stages, only the step 12 spermatid observed in V stage.

• Journal of the Korean Society for Railway
• /
• v.8 no.6 s.31
• /
• pp.581-585
• /
• 2005

In this study, the environmental impacts of a bogie in the electric motor unit(EMU) were evaluated quantitatively using simplified life cycle assessment(S_LCA). Target was the bogie and life cycle inventory(LCI) database for the bogie was established. The software used for simplified LCA was PASS. Environmental impacts with the parts of the bogie were dependent on their weight significantly. Among impact categories, abiotic resource depletion(ARD) and global warming(GW) were shown dominantly. Global warming was occurred mainly due to the emission of CO₂released from energy consumption and abiotic resource depletion was caused mostly by the consumption of iron ore for the manufacturing of steel. Therefore, the environmental impacts of the bogie could be reduced by the light-weighting of EMU and the improvement of energy efficiency.

• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
• /
• 2006.05a
• /
• pp.20-24
• /
• 2006

In this paper we investigated the method of examining the accelerated life test on LED traffic signal module by the temperature. The longevity presumption of the LED type signal light by a general heat cycle test used and executed cycle when it was done to longevity by the heat cycle test number and the acceleration factor of a real system requirements of this heat cycle test. Therefore, it reports on the introduction of the acceleration type from which the LED traffic signal module is done here to clarify the above-mentioned acceleration factor with the object and the acceleration factor is requested the test atmosphere actually in the system requirements.

• Journal of Photoscience
• /
• v.10 no.2
• /
• pp.189-193
• /
• 2003

The effects of light on the regulation of ethylene biosynthesis during development of mung bean seedlings were investigated by monitoring the differential expression of seven 1-aminocyclopropane-l-carboxylate (ACC) synthase and two ACC oxidase genes. Among them, only the expression of VR-ACS1, VR-ACS6, VR-ACS7, VR-ACO1 and VR-AC02 was observable in etiolated mung bean hypocotyls. When the seedlings were de-etiolated for 1 d under a light/dark cycle of 16 h/8 h, the expression of VR-ACS6, VR-ACS7 and VR-ACO2 was controlled negatively by light. The expression of VR-ACS1 showed a tendency to increase until 6 h after a dark-to-light transition and then decreased at 12 h. On the other hand, the expression of VR-ACO1 was mostly constitutive up to 12 h after the dark-to-light transition. The opening of hypocotyl hooks during de-etiolation in the light was stimulated by the inhibition of the action of endogenous ethylene in the presence of 1-MCP. These results suggest that the negative regulation of light on the expression of ACC synthase and ACC oxidase genes eventually results in the inhibition of ethylene production with an acceleration of the opening of apical hooks.

• Journal of Ginseng Research
• /
• v.32 no.4
• /
• pp.347-356
• /
• 2008

Forest-grown American ginseng (Panax quinquefolius L.) is exposed to daily and seasonal light variations. Our goal was to determine the effect of understory light changes on the maximum quantum yield of photosystem II, expressed as $F_v/F_m$, and photosynthetic pigment composition of two-year-old plants. Understory light photon flux density and sunfleck durations were characterized using hemispherical canopy photography. Our results showed that understory light significantly affected the $F_v/F_m$ of American ginseng, especially during the initial development of the plants when light levels were the highest, averaging 28 mol $m^{-2}d^{-1}$. Associated with low $F_v/F_m$ during its initial development, American ginseng had the lowest levels of epoxidation state of the xanthophyll cycle of the season, suggesting an active dissipation of excess light energy absorbed by the chlorophyll pigments. As photon flux density decreased after the deployment of the forest canopy to less than 10 mol $m^{-2}d^{-1}$, chlorophyll a/b decreased suggesting a greater investment in light harvesting pigments to reaction centers in order to absorb the fleeting light energy.

• Journal of Korean Society of Water and Wastewater
• /
• v.31 no.5
• /
• pp.441-445
• /
• 2017

This study aimed to investigate growth rate and nutrient consumption of Chlorella vulgaris according to different light irradiation interval. Applied light irradiation intervals were 12 hr, 4 hr, 1 hr, and 1 min. The light source was flexible LED(Blue:Red=1:1), light intensity was 200 PPFD and Light/Dark cycle was 1:1. As a result, growth rate and nutrient removal efficiencies showed no significant differences depending on the light irradiation interval. Considering the reproduction characteristics of applied microalgae cultures of this study, this is thought to be one of the possible reasons of above results. Because Chlorella vulgaris performs an asexual reproduction and it is known that there is no significant relationship between light irradiation interval and growth rate, including nutrient consumption in case of asexual reproduction.