• Korean Journal of Microbiology
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• v.27 no.3
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• pp.291-296
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• 1989

Campylobacter jejuni was studied for its disinfection by heat-and cold-treatment and UV-irradiation. When C. jejuni was treated by heat, no viable cell was found after 10 min treatment at $55^{\circ}C$, whereas small fraction of cell population was survived after 60 min treatment at $45^{\circ}C$ and $50^{\circ}C$. When they were treated by cold temperature for 30 days, no cell was survived at -$23^{\circ}C$ but about 4 log of the cells were survived at both temperature of $4^{\circ}C$ and -$40^{\circ}C$. When the organisms were UV-irradiated, thier survival rates were proportionally varied to the distance of irradiation. The scanning electron microscopic studies of C. jejuni cells treated by the disinfecting agents revealed that shapes of thecells were deformed from spiral rod into spherical form. The heat-treated cells showed rough and damaged surface on the scanning electron micrographs. In the heat-treated cells, some proteins of high molecular weight appeared to become accumulated in the electrophoretic analysis. The DNAs extracted from the cells treated with the physical agents showed some differences in agarose gel electrophoresis, comparing those of normal cells.

• 한국정보디스플레이학회:학술대회논문집
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• 2009.10a
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• pp.246-249
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• 2009

A compact, flexible family of UV laser material processing systems has been developed to drive advancements in both large area processing and annealing of semiconductor surfaces. UV photons can either be applied via demagnifying a mask pattern image or by scanning a homogenized excimer beam across the substrate area. 193nm, 248nm and 308nm wavelength applications are supported.

• Journal of Adhesion and Interface
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• v.9 no.2
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• pp.1-7
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• 2008

Using biodegradable polycaprolactone, the microcapsules were prepared by solvent evaporation method. Retinol was selected as a core material, which was used as an important ingredient material in cosmetic fields. Poly(vinyl alcohol) was used as a stabilizer. The shape and property of the microcapsules were characterized by scanning electron microscope and differential scanning calorimeter, and the release rate of the microcapsule was measured by UV spectrophotometer. The microcapsules were prepared, changing the concentration of wall material, the stirring rate, and the concentration of stabilizer. Under the optimum condition, the microcapsules were formed, which showd 5~6 um in diameter and got the homogeneous sphere shape.

• Bulletin of the Korean Chemical Society
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• v.32 no.5
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• pp.1657-1661
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• 2011

In this study, CdSe-$TiO_2$ photocatalyst were synthesized by a facile solvothermal method and characterized by X-ray diffraction (XRD), Scanning electron microscopy (SEM) with energy dispersive X-ray (EDX) analysis and UV-vis diffuse reflectance spectrophotometer. The photocatalytic activity was investigated by degrading methylene blue (MB) in aqueous solution under irradiation of UV light as well as visible light. The absorbance of degraded MB solution was determined by UV-vis spectrophotometer. The results revealed that the CdSe-$TiO_2$ photocatalyst exhibited much higher photocatalytic activity than $TiO_2$ both under irradiation of UV light as well as visible light.

• Journal of the Korean Society for Precision Engineering
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• v.23 no.12 s.189
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• pp.117-121
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• 2006

Generally, micro-stereolithography technology uses laser and complex optical system as light source and light delivery system, respectively. In this research, a novel micro-stereolithography technology that uses UV lamp that is more economical than UV laser as light source and optical fiber that is simpler than previous light delivery system has been developed. Furthermore, precise control system that is composed of 3-axis linear stage and shutter has been used to fabricate truly three dimensional micro-structure. For confirming the feasibility of developed micro-stereolithography apparatus, the solidification experiments were conducted. The solidification widths and depths datum of photopolymer as varying scanning speed of the UV light have been obtained. Using developed apparatus, some micro structures were fabricated successfully.

• Macromolecular Research
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• v.11 no.6
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• pp.495-500
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• 2003

UV-induced graft polymerization of glycidyl methacrylate (GMA) to a polypropylene (PP) membrane was carried out in the vapor phase with benzophenone (BP) as a photoinitiator. Attenuated total reflection Fourier transform infrared spectroscopy, atomic force microscopy (AFM), and scanning electron microscopy (SEM) were utilized to characterize the copolymer. The degree of grafting increased with increasing reaction time, increased UV irradiation source intensity, and increased immersion concentration of the BP solution. The optimum synthetic condition for the PP-g-GMA membrane was obtained with a reaction time of 2 hrs, a UV irradiation source intensity of 450 W, and an immersion concentration of the BP solution of 0.5 mol/L. The pure water flux decreased upon increasing the degree of grafting and increasing the amount of diethylamino functional group introduced. The analysis of AFM and SEM images shows that the graft chains and diethylamino groups of PP-g-GMA grew on the PP membrane surface, resulting in a change in surface morphology.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.28 no.9
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• pp.1270-1275
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• 2004

Standard positive photoresist techniques were adapted to generate nano-scale patterns of gold substrate using self-assembled monolayers (SAMs) and femtosecond laser. SAMs formed by the adsorption of alkanethiols onto gold substrate are employed as very thin photoresists, Alkanethiolates formed by the adsorption of alkanethiols are oxidized on exposure to UV light in the presence of air to alkylsulfonates. Specifically, it is known that deep UV light of wavelength less than 200nm is necessary for oxidation to occur. In this study, ultrafast laser of wavelength 800nm and pulse width 200fs is applied for photolithography. Results show that ultrafast laser of visible range wavelength can replace deep UV laser source for photo patterning using thin organic films. Femtosecond laser coupled near-field scanning optical microscopy facilitates not only the patterning of surface chemical structure, but also the creation of three-dimensional nano-scale structures by combination with suitable etching methods.

• Korean Journal of Optics and Photonics
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• v.15 no.3
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• pp.214-221
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• 2004

We theoretically and experimentally investigate the effect of apodization on the transmission characteristics of linearly chirped fiber Bragg gratings(CFBGs). Based on the UV beam scanning method along a phase mask, we fabricated several apodized CFBGs with different apodization profiles such as Gaussian, Raised-cosine, Blackman, and Hyperbolic tangent. During the UV beam scanning, the phase mask is dithered by a PZT(Piezoelectric transducer) which is precisely controlled by a computer program so that the apodization profiles can be flexibly applied to the grating. We measured the reflection spectra and group delay characteristics of CFBGs with the different apodization profiles, and compared them according to their properties such as reflectivity, sidelobes, and group delay ripple (GDR). The peak-to-peak of GDR could be suppressed to less than 20 ps.

• Journal of Biomedical Engineering Research
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• v.17 no.4
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• pp.479-490
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• 1996

To utilize collagen as an implantable biomateriall the mcct widely used bovine skin origin Type I collagen was investigated Pepsin treated, Type I atelocollagen was extracted and crosslinked by the ultraviolet(W) ray with wavelength of 254nm or by various concentrations of glutaraldehyde to produce collagen membranes. The crosslink rates of the specimens were observed by a polarized light microscope, a scanning electron microscope, and a Fourier transform infrared (FT-lR) spectrometer. The followings are concluded 1. The collagen membranes produced by both 2.5% glutaraldehyde solution and 254nm UV ray irra- diation demonstrated similar morphologies on polarized light microscopic and scanning electron microscopic views. 2. The chemical structures of the crosslinked membranes by glutaraldehyde over 2.5% in concentrations revealed similar intensities to that of the UV ray irradiated one in FT-lR investigation. 3. To obtain optimal croulink in bovine stalin origin Type I atelocollagen, 2.5% glutaraldehyde solution or UV ray irradiation with 254nm wavelength is acceptable.

• Applied Chemistry for Engineering
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• v.20 no.5
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• pp.511-516
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• 2009

Photodegradation characteristics of polyolefin composites were studied. Thermogravimetric analysis results suggest that the polyolefin blends used in this study have different amounts of talc. The mechanical behaviors of polyolefin blends, which experienced UV-irradiation in accordance with SAE J1960, are investigated using tensile and Izod impact tests. These results show that as the UV-exposure time increases, a significant drop in the elongation at break and impact strength at a low temperature are observed. This may be explained by the decreases in elastic energy derived from the scission of polymer molecular chains and the low density of entanglement after UV- photodegradation. Scanning electron microscopy observations indicate that no crack and surface damage are observed, while the additional talc particles are exposed, on the UV-exposed surfaces. The exposure of talc particles may be responsible for the discoloration of UV-exposed polyolefin blend surface. Observation using Fourier transform infrared spectroscopy (FT-IR) confirms the presence of photodegradation on the surface of UV-exposed polyolefin blend.