• Polymer(Korea)
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• v.31 no.5
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• pp.393-398
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• 2007

We studied the mechanism of liquid crystal alignment on polyvinylfluorocinnamate (PVCN-F) films which were irradiated by UV using polarized fourier transform infrared (FT-IR) spectroscopy and ultraviolet/visible (UV/Vis) spectroscopy. UV irradiation of PVCN-F films caused decrease of vinylene -C=C- stretching peak area at $1638cm^{-1}$ and shift of conjugated C:0 stretching vibration at $1712cm^{-1}\;to\;1734cm^{-1}$ which is caused by nonconjugated C=O stretching nitration. To study the orientation direction of 5CB liquid crystal (LC) molecules in the liquid crystal cell with PUV irradiation, rubbing treatment or without any treatment on the PVCN-F alignment layer, we used polarized FT-IR dichroism technique. We successfully measured 5CB LC alignment directions, which are perpendicular to the irradiated PUV polarization direction and parallel to the rubbing direction in the liquid crystal cell without using dichroic dyes.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.16 no.1
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• pp.25-31
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• 2006

Many amethysts of different origins such as South America, Aftrica, and Asia were compared. According to ICP-AES analysis, the colorizing elements were Fe, Cr, Cu, and Co. Amethysts from South America showed higher concentrations of the elements. UV- VIS analysis showed that both natural and synthetic amethysts were characterized by the higher absorption at 350 nm and 550 nm wavelength. The natural amethysts had lower permeability than that of the synthetic amethysts. According to FT-IR analysis, the synthetic amethysts were distinguished from the natural amethysts in that they had a typical absorption band of $3543cm^{-1}$. The amethyst from South America showed strong absorption bands of $3584cm^{-1}\;and\;3435cm^{-1}$, and African amethyst had absorption bands of $3299cm^{-1}\;and\;3196cm^{-1}$. $3381cm^{-1}$ absorption band was shown strongly for Asian origins.

• Fashion & Textile Research Journal
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• v.23 no.3
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• pp.406-414
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• 2021

This study aimed to evaluate the inhalation resistance(IR) and fiber structure of disposable masks when exposed to repeated heating and ultraviolet(UV) sterilization. The experiments consisted of a lab-scale and a field test. For the lab-scale test, KF94 and N95 masks were selected and a trial was composed of three repetitions of an 80-min sterilization. For the field test, a subject participated over four days, of which a KF94 was worn without sterilization, and the same trial was conducted during the next four days with daily sterilization. The results showed that the IR of the KF94 mask(9.5 Pa) gradually increased according to the sterilization up to the second repetition(15.6 Pa) but decreased at the third treatment(9.7 Pa). However, the N95 mask did not showany tendency of IR during the repetitions. Microscope photos showed several warped or blackened fibers in the stiffener layer after the repeated sterilization. After wearing a KF94 mask for four consecutive days, its IR decreased until the three days but increased the fourth day, whereas another KF94 mask with sterilization showed an increase in IR for the four days. In the microscope-photos after the consecutive four days, outside fibers and stiffener layers were warped or became less dense. In summary, the IR of the KF94 mask slightly increased through the three~four rounds of heating and UV sterilizations, but the fiber structures were not significantly deformed by the repeated sterilization. To reduce discarded mask waste, the repeated sterilization of masks can be recommended.

• Analytical Science and Technology
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• v.13 no.3
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• pp.282-290
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• 2000

In this study, polymer additives were extracted and separated by Soxhlet extraction method and the dissolution-precipitation method from a polycarbonate (optical grade) which completely absorbed UV light below 390 nm. Analytical techniques such as UV-Vis spectroscopy, FT-IR, and HPLC were applied to analyze additives in polycarbonate. Separated materials from the polycarbonate may be a complex mixture containing additives such as UV stabilizer, antioxidants (primary and secondary), monomers, and oligomers. Several compounds such as bisphenol A, Irganox 1010, and Cyasorb UV-5411 were identified by chromatograms and UV spectra obtained from RP HPLC analysis using Bondapak $C_{18}$ column, methanol mobile phase, and a photodiode array (PDA) detector. Also, the content of UV-5411 in the polycarbonate was about 0.12 wt% by a quantitative analysis through UV spectroscopy.

• 프린팅코리아
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• v.7 no.8
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• pp.134-137
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• 2008

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.24 no.12
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• pp.47-56
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• 2010

For a human being's smooth activity, the clean air and comfortable lighting environment are needed. The suitable lighting environment is obtained generally by making it available for being formed the bright situation easy for seeing object and the visually comfortable atmosphere. In this way, even the lighting environment was changed along with economic development. Even a light source was diversified. Thus, several kinds of new light sources such as LED, OLED, PLS, and CNT came to appear. Halogen lamp, which has low efficiency due to high color rendering among lamps of being used now, is being much used yet. However, owing to radiation of UV and IR, there are many limitations to the subject in general exhibition lighting, museum, and art museum. Accordingly, a research was performed on filter that is blocked UV and IR at the same time, by using halogen lamp that is excellent in color rendering and in life.

• Bulletin of the Korean Chemical Society
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• v.35 no.2
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• pp.531-538
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• 2014

The quantum mechanical properties of a series of oligo-para-phenylenes (2-11) were characterized using DFT B3LYP/6-311G(d,p) calculations. The global minimum among the various torsional conformers of an oligo-p-phenylene is calculated to be a twist conformation. A less stable planar conformation, in which all the dihedral angles in oligo-p-phenylene are restricted to be planar, has also been calculated. The total electronic energies, normal vibrational modes, Gibbs free energies, and HOMOs and LUMOs of the two different conformations (twisted and planar) of the oligo-p-phenylenes were analyzed. The energy differences between the HOMOs and LUMOs of the substrates are in accord with the maximum absorption peaks of the experimental UV spectra of 2-6. The calculated normal vibrational modes of 2-6 were comparable with their experimental IR spectra.

• Journal of Korean Society of Environmental Engineers
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• v.27 no.10
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• pp.1129-1135
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• 2005

In this study. the applicability of a rotating reactor for the oxidative removal of aqueous humic substances extracted from the Han River in Seoul, Korea was investigated. As air blowing for proper mixing of $TiO_2$ photocatalyst could inhibit UV-irradiation between a UV lamp and photocatalyst by air bubbles, a rotating reactor with some baffles was used for better UV-irradiation effect in this study. Han River humic substances are different from the other commercial humic substances(e.g., from Aldrich and International Humic Substance Society). Their characteristics were investigated with structural and spectroscopic analyses using FT-IR(Fourier transform-infrared), and $^{13}C$-NMR (nuclear magnetic resonance). The humic substances were extracted by XAD-7HP and treated with $TiO_2$-coated hollow beads under UV-A and UV-C irradiation in order to solve problems of separation and recovery of photocatalyst after reaction. At approximately 5 mg/L of initial TOC concentration, pH 3 and $2.0\;g-TiO_2/L$ dose, photocatalytic oxidation of Han River humic substances showed the optimum removal efficiency. Also, UV-C and UV-A lamps showed similar TOC removal efficiency. However, under UV-C irradiation, Han River humic substances were degraded to smaller compounds and increased the proportion of low molecular weight fractions compared to UV-A.

• Journal of the Korean Ceramic Society
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• v.40 no.2
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• pp.184-190
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• 2003

$Sr_{0.9}Bi_{2.1}Ta_2O_9$thin films were deposited on $IrO_2$ electrode by spin coating method using photosensitive sol-gel solution. To ensure the UV-exposure effect on SBT thin films, UV irradiated films and non-UV irradiated films were analyzed by XRD, SEM. As a result, UV-irradiation on SBT thin films promoted grain growth of SBT compared with no UV irradiation. In case of the UV irradiated films annealed at$740{\circ}C$for 1 h in an oxygen ambient, the 2Pr value and Pr/Ps at${pm}5$V were$11.48{mu}C/cm^2$and 0.53, respectively. 2Pr values of the UV irradiated SBT thin films at$660-740{circ}C were approximately 12% higher than those of non-UV irradiated thin films.

• Journal of the Institute of Electronics Engineers of Korea SP
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• v.38 no.1
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• pp.79-88
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• 2001

The target such as aircraft operates flares to protect itself from the missile. In general, Infra-red(IR) flares that are hot bodies radiating energy considerably greater than it does, so cause the missile to guide the flare instead of the target. For a precise target tracking in spite of a presence of flares, therefore, the seeker should discriminate the target signal from various clutters including the flare and the background. In this paper, we simulated 2-color rosette scan seeker using IR and UV(UltraViolet) bands. In each wave band, we analyzed the radiant distributions of the target, the flare, and background. These results showed that a simultaneous process in two bands can detect precisely the target.