• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2001.11b
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• pp.108-111
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• 2001

ZnO thin films on (001) sapphire substrates have been deposited by pulsed laser deposition(PLD) technique for light emitting device applications. We have controlled the emission intensity of UV and visible light, depending on film thickness and various post-annealing time. UV emission became strong as the thickness of ZnO thin films increased. The intensity of visible light was strong as post-annealing temperature increased. The optical properties of the ZnO thin films were characterized by PL(photoluminescence) and the structural properties of the ZnO were characterized by XRD for the application of ZnO light emission device.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2001.11a
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• pp.108-111
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• 2001

ZnO thin films on (001) sapphire substrates knave been deposited by pulsed laser deposition(PLD) technique for light emitting device applications. We have controlled the emission intensity of UV and visible light, depending on film thickness and various post-annealing time. UV emission became strong as the thickness of ZnO thin films increased. The intensity of visible light was strong as post-annealing temperature increased. The optical properties of the ZnO thin films were characterized by PL(photoluminescence) and the structural properties of the ZnO were characterized by XRD for the application of ZnO light emission device.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.9 no.3
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• pp.56-61
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• 2010

Recently, UV pulse laser is widely used in micro machining of the research, development and industry field of IT, NT and BT products because the laser short wavelength provides not only micro drilling, micro cutting and micro grooving which has a very fine line width, but also high absorption coefficient which allows a lot of type of materials to be machined more easily. To analyze the dynamic deformation during a very short processing time, which is nearly about several tens nanoseconds, the commercial Finite Element Analysis (FEA) code, LS-DYNA 3D, was employed for the computitional simulation of the UV laser micro machining behavior for thin copper material in this paper. A finite element model considering high strain rate effect is especially suggested to investigate the micro phenomena which are only dominated by mechanically pressure impact in disregard of thermally heat transfer. From these computational results, some of dynamic deformation behaviors such as dent deformation shapes, strains and stresses distributions were observed and compared with previous experimental works. These will help us to understand micro interaction between UV laser beam and material.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.44 no.5
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• pp.15-20
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• 2007

We fabricated ZnO thin films on quartz substrate using pulsed laser deposition method and investigated structural and optical properties of ZnO thin films with various substrate temperatures. Regardless of the substrate temperature variation, all ZnO thin films had grown to (002) and the thin film deposited at 400 $^{\circ}C$ exhibited an excellent crystallinity having 0.24$^{\circ}$ of Full-Width-Half-Maximum (FWHM). In the result of photoluminescence property, UV and deep-level emission peaks were observed in all ZnO films and the emission peaks were changed with various substrate temperatures. An highest UV emission was exhibited on the specimen deposited at 400 $^{\circ}C$ and the FWHM of UV peak was 14 nm. The optical transmittance was about 85 % in visible region regardless of the substrate temperature. The comparison result of the bandgap energies obtained from optical transmittance and UV emission centers, the two values were about the same. From these results, it is found that UV emission center has close relationship with near band edge emission of ZnO thin film.

• Bulletin of the Korean Chemical Society
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• v.33 no.12
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• pp.3937-3938
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• 2012

• Journal of the Korea Institute of Information and Communication Engineering
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• v.12 no.1
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• pp.158-163
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• 2008

Ozone monitor based on UV techniques has been widely used due to their signal stability. The high concentration ozone monitor for real time ozone monitoring from ozone generator was composed of a low pressure mercury lamp as UV source and a photo multiplier tube as UV detector. The structure could be very useful for low price high concentration ozone monitor and showed good linearity to ozone in the concentration range between 0.05 and 2wt%. For accurate ambient ozone monitoring, the system composed of a high power pulsed xenon lamp as UV source, an optical spectrometer with a high sensitivity linear CCD array as UV detector. The optical signal form the CCD array was converted to digital signal, and the digital signal was displayed on screen using PC interface. The developed system showed good linearity and sensitivity in relatively low measuring range between 10ppm and 10,000ppm, and showed some feasibility of hish resolution ozone monitor using CCD array as a photodetecor.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.24 no.7
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• pp.537-542
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• 2011

Recently, n-InZnO/p-CuO oxide diode has attracted great attention due to possible application for selector device of 3-dimensional cross-point resistive memory structures. To investigate the detailed properties of InZnO (IZO), we have deposited IZO films on the fused quartz substrate using PLD (pulsed laser deposition) method at oxygen pressure of 1~100 mTorr and substrate temperature of RT$\sim600^{\circ}C$. The influence of oxygen pressure and substrate temperature on structural, optical and electrical of IZO films is analyzed using XRD (x-ray diffraction), SEM (scanning electron microscopy), UV-Vis spectrophotometry, spectroscopic ellipsometry (SE) and hall measurements. The XRD results shows that the deposited thin films are polycrystalline over $300^{\circ}C$ of substrate temperature independent of oxygen pressure. The resistivity of films was increased as oxygen pressure and substrate temperature decrease. The thickness and optical constants of the deposited films measured with UV-Vis spectrophotometer were also compared with those of broken SEM and SE results.

• 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.

• Proceedings of the IEEK Conference
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• 2002.06e
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• pp.201-204
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• 2002

A high accuracy ozone monitor using UV absorption method was developed for ambient ozone monitoring. The system was mainly composed of a high power pulsed xenon lamp as UV source, an optical spectrometer with a high sensitivity linear CCD array as UV detector and signal processing unit. The optical signal from the CCD array that provides unusually high response and excellent optical resolution for ozone concentration was converted to digital signal and the digital signal was displayed on screen using PC interface. The optical signal was propagated using optic fiber to reduce optical loss to increase the accuracy of the measuring system. This paper has been studied a interworking signalling protocol between two hybrid networks by analyzing Satellite B-ISDN architecture, DSS2 Layer 3 Signalling protocol, B-ISUP protocol, S-BISUP protocol stack and so on. Also in the paper, messages and primitives have been defined for B-ISDN's Connection Type, Ownership and each protocol in order to connect point-to-multipoint. The ozone sensing properties of the CCD ozone monitor was compared with those of the photo multiplier ozone monitor.

• Proceedings of the Korean Vacuum Society Conference
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• 2015.08a
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• pp.88.1-88.1
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• 2015

In recent printed electronics technology, Photo-Sintering, a technique for sintering materials using a light source, has attracted attention as an alternative to time-consuming high-temperature thermal processes. The key principle of this technique is the selective heating of a strongly absorbent thin film, while preventing the heating of the transparent substrate by the light source. Many recent studies have used a flash lamp as the light source, and investigated the material-dependent effect of the width or intensity of the pulsed light. However, the flash lamp for sintering is not suitable for industry yet, because of needing too high power to sinter for a large scale. In energy-saving and large-scale sintering, LED technologies would be very useful in the near future. In this work, we investigated a sintering process for silver nanoparticles using UV-LED array. Silver nanoparticles in ink were inkjet-printed on a $1{\times}1cm$ area of a PET film and photo-sintered by 365 nm UV-LED module. A sheet resistance value as low as $72.6m{\Omega}/sq$ (2.3 - 4.5 times that of bulk silver) was obtained from the UV-LED sintering at 300 mW/cm2 for 50 min.