• Polymer(Korea)
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• v.26 no.2
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• pp.209-217
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• 2002

We studied the mechanism of orientation of polyimide molecules which were irradiated by polarized UU (PUV) using polarized Fourier transform infrared (FT-IR) spectroscopy and ultraviolet (UV) spectroscopy, According to the measured UV spectra, we found PI films mainly absorb UV light less than 350 nm wavelength, therefore, UV light less than 360 nm induces photochemical reaction of PI. PUV irradiation of PI films caused decrease of all peak intensities in the FT-IR spectra. except the newly formed broad peak at $3244 cm^{-1}$, due to degradation of the PI molecules. The remaining PI molecules after photo-degradation showed predominantly perpendicular molecular orientation to the irradiated PUV polarization direction, due to the preferential degradation of PI molecules parallel to irradiated PUV polarization direction. However the rubbing of PI films induced reorientation of the PI molecules parallel to the rubbing direction. We also investigated the alignment of the liquid crystal by rubbing or PUV irradiation. Liquid crystals align perpendicular to the PUV polarization direction and parallel to the rubbing direction.

• Polymer(Korea)
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• v.26 no.4
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• pp.431-438
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• 2002

We studied the orientation behavior and thermal stability of polyimide (PI) molecules under irradiation of polarized UV (PUV) using polarized fourier transform infrared (FTIR) spectroscopy. In the case of PUV-exposed PI films, the remaining PI molecules after photo-degradation showed molecular orientation perpendicular to the irradiated PUV polarization direction predominantly, due to the preferential degradation of PI molecules parallel to the irradiated PUV Polarization direction. On the other hand, the rubbing of PI films induced reorientation of the PI molecules parallel to the rubbing direction. We also investigated the thermal stability of the alignment layers furled by rubbing and PUV irradiation on the PI films using Polarized FTIR. The thermal stability of the PUV irradiated PI alignment layer is lower than that of the rubbed PI layer due to the fragmentation reaction of the PI by PUV.

• Journal of Korean Society of Water and Wastewater
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• v.26 no.2
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• pp.313-319
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• 2012

This study investigated the relative degradation of commonly known endocrine-disrupting compounds such as bisphenol A (BPA) and 17${\beta}$-estradiol (E2) using ultrasound (US) and pulsed ultraviolet (PUV) in water. The removal efficiency of BPA and E2 was determined as a function of generating power and $H_{2}O_{2}$ production. The ultrasound and PUV irradiation of the aqueous solution was performed in 3 L and 90 L stainless reactor at a constant temperature of $20^{\circ}C$ with an applied power of 200 W and 2000 W, respectively. The removal of BPA and E2 by US and PUV varied with catalysts. The experiments were conducted under the following conditions: total operating time, 30 min; initial concentration, 1 uM. In the case of E2 (10 min), % removal was 92.5/95.8/87.6/82.4, while % removal of BPA (10 min) was 62.3/82.3/91.1/67.0/64.3 in various conditions (PUV, $PUV+H_2O_2$, PUV+wire mesh, $PUV+TiO_2$ coated wire mesh), respectively.

• Journal of Korean Society of Environmental Engineers
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• v.39 no.10
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• pp.575-580
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• 2017

Chlorinated hydrocarbons (TCE and PCE), petroleum hydrocarbons (BTEX, PAHs, and TPH), and explosive compounds (TNT, RDX, and HMX) have been detected in underground water countrywide. The overall objective of this study is to evaluate sono-catalytic degradation coupled with the use of PUV in order to understand the fate and transport of a representative selection of non-biodegradable contaminants (i.e., TCE, PCE, BTEX, PAHs, TPH, TNT, RDX, and HMX) in groundwater. Both ultraviolet (UV) and ultrasound (US) systems are used in degrading of organic contaminants and they can thus be applicable simultaneously as an UV/US hybrid system in attempts further to increase the degradation efficiency. Results indicate that synergistic effect of UV/US hybrid system is closely correlated to the enhancement of sono-chemical reactivity with the UV-US interaction of increasing the formation rate of OH by providing additional $H_2O_2$ production through the pyrolysis of water molecules during UV/US hybrid irradiation.

• 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 Soil and Groundwater Environment
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• v.20 no.4
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• pp.1-7
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• 2015

The degradation of off-flavors which is 2-Methylisoborneol (2-MIB) and geosmin by means of ultrasound (US) and pulsed ultraviolet (PUV) irradiation and its combination with catalyst (wire mesh, wire mesh coated TiO₂, and TiO₂) and additive (H₂O₂) were investigated via water system. A combination treatment of TiO₂ and H₂O₂ heterogeneity with US (24 kHz) and PUV (6000 W) has shown improved results in destroying 2-MIB and geosmin, which may be attributed to chain reactions by the enhanced formation of hydroxyl radicals (·OH) through H₂O₂ dissociation and reactive oxide ions of TiO₂ addition. Rapid degradation of off-flavors occurred within 2 min under PUV process with H₂O₂ 100 mg/L (81.5% for 2- MIB; 79.3% for geosmin) and TiO₂ 100 mg/L (83.7% for 2-MIB; 79.8% for geosmin), while compared with H2O2 100 mg/L (58.4% for 2-MIB; 58.0% for geosmin) and TiO₂ 100 mg/L (59.2% for 2-MIB; 38.5% for geosmin) within 5 min under US process. Surprisingly, the emphasis was given on the comparison with the same injected energies between PUV and US on degradation efficiency. Based on the injected energy comparison, the US provided better degradation performance under equal input power of 200 kJ with H₂O₂ 100 mg/L, while compared with H₂O₂ 100 mg/L under PUV process. Our findings suggest that US can be more effective compared to PUV for the degradation of off-flavors in aspect of energy consumptions.

• Journal of Soil and Groundwater Environment
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• v.20 no.1
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• pp.36-40
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• 2015

This study examined the disinfection in combined sewer overflows (CSOs) by pulsed ultraviolet (PUV). The reflectors (stainless steel. mirror, aluminium foil, aluminium (1050), aluminium (6061), aluminium (5052), and aluminium mirror) of PUV irradiation was performed in a 90 L stainless reactor at a constant temperature of $20^{\circ}C$ and an applied power of 4000 W. The reflection efficiency of reflectors were showed 1.00 (aluminium mirror) ~ 1.48 (aluminium foil) does. The case of a rough surface analysis using SEM showed high reflectance, was the case of a smooth surface and a low reflectivity. Pseudo first-order rate constant calculated results, has a higher reflectivity values were more than twice as high compared to the low reflectivity. Affected Total coliforms disinfection time, depending on the type of reflector is considered.

• Journal of Microbiology and Biotechnology
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• v.1 no.4
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• pp.251-255
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• 1991

A 16 kilobase (kb) HindIII fragment of alkalophilic Bacillus sp. YC-335 containing a gene for xylanase synthesis was inserted at the HindIII site of pBR322 and cloned in Escherichia coli HB101. After subcloning of recombinant plasmid pYS52, the 1.5 kb fragment was found to code for xylanase activity, and the hybrid plasmid was named pYS55. The DNA insert of the plasmid was subjected to restriction enzyme mapping, which showed that pYS55 had single site for PuvII and SstI in the 1.5 kb insert fragment. Southern hybridization analysis revealed that the cloned gene was hybridized with chromosomal DNA from alkalophilic Bacillus sp. YC-335. About 64% of the enzyme activity was observed in the extracellular and periplasmic space of E. coli HB10l carrying pYS55.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.11 no.10
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• pp.878-884
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• 1998

We have investigated that the monodomain alignment of nematic liquid crystal (NLC) is obtained with polarized ultraviolet(PUV) light irradiation on polyimide (PI) surface. The LC alignment capability increases with increasing the UV light irradiation time. The polarized UV light irradiation on oblique angle of 60。 irradiated on PI surface rotated by 90。 at 10 min. after being normally irradiated on PI surface at 30 min., the generated pretilt angle of NLC is about 2.5。. The pretilt angle of NLC is attributed to the interaction between the LC molecules and the asymmetric triangular structure of polymer surface due to photo-depolymerization of polymer with the oblique UV light on PI surface. The voltage -transmittance and response time characteristics of photo-aligned twisted nematic (TN)-LCD with UV light irradiation time 60 min. were almost same in comparison with the rubbing-treated TN-LCD.

• Korean Journal of Microbiology
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• v.23 no.2
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• pp.138-146
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• 1985

A Bacillus licheniformis ATCC31667 gene coding for a glucose isomerase has been cloned and expressed in glucose isomerase negative mutant of Escherichia coli. A recombinant plasmid, constructed by ligation of a EcoRI fragment of B.licheniformis chromosomal DNA to vector plasmid pBR322, was expressed glucose isomerase positive in E.coli LE392-6 with growth on minimal medium containing xylose as a sole carbon source. This recombinant plasmid, designated pBGI6, had the insery of 4.1Kb of Bacillus gene in EcoRI site, and restriction map of the plasmid was established. The plasmid pBG16 was very stable after 10days of serial transfer to a fresh medium. The activity of glucose isomerase from the transformed cell containing pBGI6 was increased about 20 fold than its wild type of host.