• Korean Journal of Fisheries and Aquatic Sciences
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• v.40 no.3
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• pp.122-127
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• 2007

Photosensitized extracts of 28 seaweed species were tested in vitro to examine the variation in their algicidal activities against the toxic microalga Cochlodinium polykrikoides. When both seaweed extracts and microalgae were exposed to UV and visible light, methanol extracts of Porphyra yezoensis showed 5.7- and 4.4-fold increasesin light-dependent algicidal activity, respectively. When only seaweed extracts were exposed to both UV (365 nm) and visible light (white lamp) at the same time, methanol extracts of Enteromorpha linza and Carpopeltis affinis showed 3.3- and 3.4-fold increases in algicidal activity, respectively. When UV-photosensitized extracts were left in the dark, the algicidal activity of Ecklonia cava increased 13-fold after 5 h. When visible light-photosensitized extracts were left in the dark, the algicidal activity of Monostroma nitidum increased by 3.3-fold in 1 h.

• Proceedings of the KIEE Conference
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• 1996.07c
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• pp.1851-1853
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• 1996

In this paper the criteria for insulating oil condition of pole transformer were suggested by applying the UV-Visible spectrophotometric method. Ageing of insulating oil caused the change in absorbances of oil os well os the deterioration of electrical properties of oil. By comparing the electrical properties such as $tan{\delta}$ and breakdown voltage with the UV-Visible absorbances of oil, criteria for absorbance values determining oil condition were established. This UV-Visible spectrophotometric method might be applied in ageing analysis of oil and be expected to replace the current method.

• Journal of Astronomy and Space Sciences
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• v.14 no.1
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• pp.87-93
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• 1997

Radiometers in UV and visible wavelengths were onboard the Korean Sounding Rocket(KSR)-1 and 2 which were launched on June 4th and September 1st, 1993. These radiometers were designed to capture the solar radiation during the ascending period of the rocket flight. The purpose of the instrument was to measure the vertical profiles of stratospheric ozone densities. Since the instrument measured the solar radiation from the ground to its apogee, it is possible to investigate the altitude variation of the measured intensity and to estimate the effect of atmospheric scattering by comparing the UV and visible intensity. The visible channel was a reference because the 450-nm wavelength is in the atmospheric window region, where the solar radiation is transmitted through the atmosphere without being absorbed by other atmospheric gases. The use of 450-nm channel intensity as a reference should be limited to the altitude ranges above the certain altitudes, say 20 to 25km where the signals are not perturbed by atmospheric scattering effects.

• KEPCO Journal on Electric Power and Energy
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• v.7 no.2
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• pp.309-316
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• 2021

For the detection of the state of charge in VRFB-ESS, the analyses of UV-Visible spectrometry and the measurements of potential between the anolyte and catholyte were used in parallel. This paper includes the production of 4-valant ion from VOSO4 powder, 3- and 5-valant ions from electrochemical charge of 4-valant ion and 2-valant ion from 3-valant ion. It also includes the analyses of these valance ions and unknown electrolyte at any time using UV-Visible spectrometry. Through the analyses of the valance ions in samples, the SOCs of the samples at any charge-discharge times were verified.

• The Proceedings of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.10 no.5
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• pp.94-100
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• 1996

Criteria for insulating oil condition of pole transformer were suggested by applying the UV-Visible spectrophotometric method. Aging of insulating oil caused the change in absorbances of oil as well as the deterioration of electrical properties of oil. By comparing the electrical properties such as tan$\delta$ and dielectric breakdown voltage with the UV-Visible absorbances of oil, following criteria for absorbance values determining oil condition were established, fair condition is below 0.580, need attention is 0.580-0.900 and poor condition is above 0.900. This W-Visible spectrophotometric method may be applied in aging analysis of oil and expected to replace the current visual method. It is necessary to develop cheap, light and portable UV-Visible spectrophotometer in near future for field application.

• Korean Journal of Materials Research
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• v.26 no.2
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• pp.73-78
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• 2016

$TiO_2$ nanoparticles were synthesized by a sol-gel process using titanium tetra isopropoxide as a precursor at room temperature. Ag-doped $TiO_2$ nanoparticles were prepared by photoreduction of $AgNO_3$ on $TiO_2$ under UV light irradiation and calcinated at $400^{\circ}C$. Ag-doped $TiO_2$ nanoparticles were characterized for their structural and morphological properties by X-ray diffractometry (XRD), scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), and transmission electron microscopy (TEM). The photocatalytic properties of the $TiO_2$ and Ag-doped $TiO_2$ nanoparticles were evaluated according to the degree of photocatalytic degradation of gaseous benzene under UV and visible light irradiation. To estimate the rate of photolysis under UV (${\lambda}=365nm$) and visible (${\lambda}{\geq}410nm$) light, the residual concentration of benzene was monitored by gas chromatography (GC). Both undoped/doped nanoparticles showed about 80 % of photolysis of benzene under UV light. However, under visible light irradiation Ag-doped $TiO_2$ nanoparticles exhibited a photocatalytic reaction toward the photodegradation of benzene more efficient than that of bare $TiO_2$. The enhanced photocatalytic reaction of Ag-doped $TiO_2$ nanoparticles is attributed to the decrease in the activation energy and to the existence of Ag in the $TiO_2$ host lattice, which increases the absorption capacity in the visible region by acting as an electron trapper and promotes charge separation of the photoinduced electrons ($e^-$) and holes ($h^+$). The use of Ag-doped $TiO_2$ nanoparticles preserved the option of an environmentally benign photocatalytic reaction using visible light; These particles can be applicable to environmental cleaning applications.

• Particle and aerosol research
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• v.6 no.4
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• pp.165-172
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• 2010

Titania is widely used as an effective photocatalyst for the photodegradation of environmental pollutants in air. In this study, novel N-doped $ZrO_2/TiO_2$ photocatalysts were synthesized via sol-gel method and characterized by UV-Vis spectrophotometer, transmission electron microscope, and X-ray diffractometer. N-doped $ZrO_2/TiO_2$ photocatalysts were nano-sized with an average particle size of about 20 nm. The XRD pattern of N-doped $ZrO_2/TiO_2$ photocatalysts showed both anatase and rutile phases. The photocatalytic activity of N-doped $ZrO_2/TiO_2$ photocatalysts was evaluated by degradation of NO under UV and visible light irradiation at various parameters such as amount of photocatalyst, concentration of NO, and intensity of light. The photocatalytic activity of N-doped $ZrO_2/TiO_2$ photocatalysts was effective for the enhancement of the degradation of NO and higher than that of $TiO_2$ photocatlysts under UV and visible light irradiation.

• Bulletin of the Korean Chemical Society
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• v.32 no.1
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• pp.95-99
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• 2011

$CaTi_{1-x}Fe_xO_3(0{\leq}x{\leq}0.4)$ solid solution photocatalysts were synthesized by iron doping during the conventional solid state reaction at $1100^{\circ}C$ for 5 h and characterized by ultraviolet-visible (UV-vis) absorption spectroscopy, X-ray diffraction, morphological analysis. We found that $CaTi_{1-x}Fe_xO_3$ samples not only absorb UV but also the visible light photons. This is because the Fe substitution at Ti-site in $CaTi_{1-x}Fe_xO_3$ lattice induces the band transition from Fe3d to the Fe3d + Ti3d hybrid orbital. The photocatalytic activity of Fe doped $CaTiO_3$ samples for hydrogen production under UV light irradiation decreased with the increase in the Fe concentration. There exists an optimized concentration of iron in $CaTiO_3$, which yields a maximum photocatalytic activity under visible light ($\lambda\geq420nm$) photons.

• Korean Chemical Engineering Research
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• v.59 no.2
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• pp.165-173
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• 2021

Anti-glare (AG) coating films are applied to various display fields such as liquid crystal displays, LED lighting, and touch panels. In this study, micrometer-sized silica particles were added as fillers in the UV-curable coating solutions to provide anti-glare effect. During this process, the effects of the particle size, content, stirring time, and mixing ratio of silica particles of different sizes were investigated on the haze values and visible light transmittance of the coating films. As a result, as the size of the silica particles increased and the content of the silica particles increased, the haze values increased, but the visible light transmittance decreased. On the other hand, the stirring time did not significantly affect the haze value and transmittance of coating films. In addition, as the mixing ratio of large-sized silica particles increased, the haze value increased, but on the contrary, the visible light transmittance decreased.

• Elastomers and Composites
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• v.51 no.3
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• pp.226-232
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• 2016

We studied the photocatalytic functionality such as deodorant, antibacterial, fine dust collection efficiency of polyester-based non-woven fabric filter treated with self-actuated photocatalyst. According to UV/visible result, the UV-visible peak of visible-light responsive photocatalyst was found to be red shift at 420 nm sensitive in the visible light region. The deodorizing performance was shown to be reduced more than 80% even without dark conditions. Fine dust particles collection efficiency was shown to be excellent at the size of not only $2.5{\mu}m{\sim}10.0{\mu}m$ but also less than $2.5{\mu}m$. Also antimicrobial and antifungus was shown to be reduced more than 99.9%.