• Journal of Korean Society for Atmospheric Environment
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• v.32 no.1
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• pp.1-8
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• 2016

Optical particle sizer (OPS), optical particle counter (OPC), and aethalomter were deployed to measure the particle number concentrations from 0.3 to $10.0{\mu}m$ and black carbon (BC) concentrations. Comparisons of particle number concentrations measured by OPS and OPC were conducted to evaluate the performance of the each optical instrument at the Gwangju sampling site ($35.23^{\circ}N$, $126.84^{\circ}E$) for 14 days from Dec. 27 in 2014. Although a good correlation ($r^2=0.99$) between the OPS and OPC was observed for both the particle number and volume concentrations, different relationships by BC concentrations can be associated with the intensities by different light scattering angles. In addition, based on diurnal patterns of size distributions in 24 hr running correlation coefficient determination, BC concentrations were highly related to the particles less than $0.3{\mu}m$ observed in the morning traffic hour.

• Journal of fish pathology
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• v.30 no.1
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• pp.51-61
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• 2017

The effect of electromagnetic field on aquatic organisms has received little attention. In the current study, the effect of 50Hz electromagnetic field on muscle histopathology of Caspian Sea Cyprinus carpio, a species of economic importance, was investigated. A total of 120 healthy fish were used in this study. They were classified randomly in one of two groups as follows: Control or unexposed EMF group and experimental group with 5 different magnetic field intensities (0.1, 1, 3, 5 and 7mT) at 2 different exposure times including 30 and 60 minutes. Fish in the experimental group were exposed only once. Two weeks after exposure, dorsal muscles sectioned transversely, stained and were examined using a light microscope. Histopathologic assessments showed significant difference between control and EMF exposed groups at both 30 min. (p<0.01) and 60 min. (p<0.001) exposure times. We report for the first time that electromagnetic field in interaction with muscular tissue of Cyprinus carpio exhibits a dual effect which depends on the field intensity, and exposure time. At short exposure time (30 min.), EMF stimulates muscle growth process. At longer exposure time (60 min.), EMF can damage muscle tissue and result in muscle necrosis. More research is required to elucidate precise mechanisms involved in muscle hypertrophy and pathologic changes.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.9 no.3
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• pp.315-319
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• 1999

Properties of both photoluminescence and long-phosphorescent for Eu, Dy-codoped $SrAl_2O_4$ powder phosphor synthesized by solid reaction method were investigated by PL instrument. Two intense peaks in the emission spectrum measured at 10 K are observed near 450 nm (2.755 eV) and 520 nm (2.384 eV) wavelength, but at 300 K the main peak of 520 nm wavelength is presented. After the removal of light excitation (360 nm), the excellent after-glow characteristic of the phosphorescence were obtained as a result of low decay tiem, although the after-glow intensities of phosphor vary exponentially with the times.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.63 no.1
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• pp.76-79
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• 2014

We report Zinc oxide (ZnO) nanorods synthesis and electrochemical luminescence (ECL) cell fabrication. The ECL cell was fabricated using the electrode of ZnO nanorods and Ru(II) complex ($Ru(bpy)_3{^{2+}}$) as a luminescence materials. The fabricated ECL cell is composed of F-doped $SnO_2$ (FTO) glass/ Ru(II)/ZnO nanorods/FTO glass. The highest intensity of the emitting light was obtained at the wavelength of ~620 nm which corresponds to dark-orange color. At a bias voltage of 3V, the measured ECL efficiencies were 5 $cd/m^2$ for cell without ZnO nanorod, 145 $cd/m^2$ for ZnO nanorods-$5{\mu}m$, 208 $cd/m^2$ for ZnO nanorods-$8{\mu}m$ and 275 $cd/m^2$ for ZnO nanorods-$10{\mu}m$, respectively. At a bias voltage of 3.5V, the use of ZnO nanorods increases ECL intensities by about 3 times compared to the typical ECL cell without the use of ZnO nanorods.

• Journal of Electrical Engineering and Technology
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• v.9 no.5
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• pp.1780-1787
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• 2014

Arterial oxygen saturation ($SpO_2$) monitoring for newborns requires special attention in neonatal intensive care units (NICUs). Newborns have very low photo-plethysmogram (PPG) amplitudes and their body movements are difficult to contain. Hardware design and its associated signal processing algorithms should be robust enough so that faulty measurements can be avoided. In this study, improved designs were implemented to deal with low perfusion, motion artifact, and the influence of ambient light. Dynamic range was increased by using different LED intensities and a feedback system. To minimize the effects of motion artifact and to discard other unqualified data, four additional algorithms were used, which were based on dual-trace detection, continuity of DC level, morphology of PPG, and simultaneity check of $SpO_2$. Our $SpO_2$ system was tested with newborns with normal respiration in the NICU. Our system provided fast, real-time responses and 100% artifact detection was accomplished under 84% of $SpO_2$.

• Textile Coloration and Finishing
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• v.30 no.4
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• pp.237-244
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• 2018

Three super hydrophobic red fluorescence dyes were selected to dye high molecular weight polyethylene fiber. Their absorbance and emission spectra were obtained and Stokes' shift was measured. Fluorescence emission strength of the dyes on the fiber was investigated and therefore Fluoro Red 3 was determined as the best one among those three dyes in this experiment. Dyeing properties and fluorescence intensities were investigated using the Fluoro Red 3 on high molecular weight polyethylene fiber at various dyeing conditions. The optimum concentration of a dispersing agent was appeared at 10wt% in aqueous solution. The best dyeing was obtained at $125^{\circ}C$ for 1 hour. The color fastnesses to the washing and rubbing were as high as ratings 4~5, however, the fastness to light was exhibited ratings 2~3.

• Elastomers and Composites
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• v.57 no.1
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• pp.1-8
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• 2022

In this study, the photo-deposition method was used to introduce Ag onto the surface of TiO₂ to synthesize an Ag-TiO₂ composite. The effects of the varying amounts of AgNO₃ precursor and annealing time periods on the Ag content in the composites, as well as their antibacterial characteristics under visible light conditions were studied. SEM analysis revealed the spherical morphology of the Ag-TiO₂ composite. Compared with TiO₂, the Ag particles were too small to be observed. An XPS analysis of the Ag-TiO₂ surface confirmed the Ag content and showed the peak intensities for elements such as Ag, Ti, O, C, and Si. The highest Ag content was observed when 33.3 wt.% of AgNO₃ and an annealing time of 6 h were employed; this was the optimum annealing time for Ti-Ag-O bonding, in that the lowest number of O bonds and the highest number of Ag bonds were confirmed by XPS analysis. Superior antibacterial properties against Bacillus and Escherichia coli, in addition to the widest inhibition zones were exhibited by the Ag-TiO₂ composite with an increased Ag content in a disk diffusion test, the bacterial reduction rate against Staphylococcus aureus and Escherichia coli being 99.9%.

• Journal of Bio-Environment Control
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• v.27 no.2
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• pp.132-139
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• 2018

The photosynthetic rate is an indicator of the growth state and growth rate of crops and is an important factor in constructing efficient production systems. The objective of this study was to develop a canopy photosynthetic rate model of romaine lettuce using the three variables of $CO_2$ concentration, light intensity, and growth stage. The canopy photosynthetic rates of the lettuce were measured at five different $CO_2$ concentrations ($600-2,200{\mu}mol{\cdot}mol^{-1}$), five light intensities ($60-340{\mu}mol{\cdot}m^{-2}{\cdot}s^{-1}$), and four growth stages (5-20 days after transplanting) in three closed acrylic chambers ($1.0{\times}0.8{\times}0.5m$). A simple multiplication model expressed by multiplying three single-variable models and the modified rectangular hyperbola model including photochemical efficiency, carboxylation conductance, and dark respiration, which vary with growth stage, were also considered. In validation, the $R^2$ value was 0.923 in the simple multiplication model, while it was 0.941 in the modified rectangular hyperbola model. The modified rectangular hyperbola model appeared to be more appropriate than the simple multiplication model in expressing canopy photosynthetic rates. The model developed in this study will contribute to the determination of an optimal $CO_2$ concentration and light intensity with the growth stage of lettuce in plant factories.

• Journal of Aquaculture
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• v.18 no.4
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• pp.299-304
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• 2005

Laboratory culture of the native kelp Kjelimaniella crassifolia and the introduced species Laminaria japonica in east coast of Korea were compared at each stage of their life cycles. In the zoospore stage, L. japonica grows optimally at a water temperature of $15{\~}20^{\circ}C$ achieving $95\%$ spore release in 24 hours, whereas K. crassifolia requires 48 hours to achieve $90\%$ spore release in these conditions. Good growth of gametophytes occurred at $10^{\circ}C$ and $15^{\circ}C$ in both species. L. japonica grows optimally under high light intensity ($80{\~}120{\mu}mol{\cdot}m^{-2}s^{-1}$) while K. crassifolia grows best under low light intensity ($40{\~}60{\mu}mol{\cdot}m^{-2}s^{-1}$). Growth of juvenile sporophytes of L. japonica was good in various water temperatures ($10{\~}20^{\circ}C$) and light levels ($40{\~}120{\mu}mol{\cdot}m^{-2}s^{-1}$) while K. crassifolia grew to optimal blade length only under specific conditions ($10{\~}40{\mu}mol{\cdot}m^{-2}s^{-1}$). While the optimal culture conditions for K. crassifolia were more constrained than those of L. japonica which tolerated a wide range of water temperatures and light intensities, the laboratory culture conditions for both of these species reflect the natural environment in which these species are found.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.52 no.1
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• pp.1-11
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• 2007

Light is an environmental component inevitably regulating photosynthesis and photo-morphogenesis, which are involved in the plant growth and development. Studies were conducted at the International Rice Research Institute, Philippines in 2004 and 2005, with aims to investigate 1) morphological responses of rice plants to low radiation, 2) morphological alteration of shade-grown plants when exposed to high light intensity, and 3) photosynthetic responses of shade-grown rice plants. Reduction in solar radiation by 40% induced increases in the area on a single leaf basis, biomass partitioning to leaves, and chlorophyll meter readings but brought about retardation of tiller development and decrease in above-ground biomass production of rice varieties. When the shade-grown plants from two weeks of transplanting to panicle initiation were exposed to full solar radiation after panicle initiation, they demonstrated less increase in chlorophyll meter readings and more decrease in leaf nitrogen concentrations from panicle initiation to flowering than control plants that were grown under the ambient solar radiation for whole growth period after transplanting. Shade-grown rice plants exhibited lower carbon assimilation rates but higher internal $CO_2$ concentrations on a single leaf basis than control plants, when measurements for shade-grown rice plants were made under the shading treatments. But when the measurements for shade-grown plants were made under the full solar radiation, light-saturated carbon assimilation rates were similar to control plants. Response of photosynthetic rates to varying light intensities was not considerably different between shading treatments and control. Yield reduction was observed in the shading treatments from panicle initiation to flowering and from flowering to physiological maturity, mainly by less spikelets per panicle and poor grain filling, respectively.