• Journal of Korean Society for Atmospheric Environment
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• v.16 no.4
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• pp.373-380
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• 2000

A new type of photocatalyst plasma air purification filter for decomposition of some VOCs has been developed. The photocatalyst plasma air purification filter employs the pulsed discharge plasma as an energy source of TiO2. photocatalyst instead of UV light. In closed room(2m3) test removal efficiency of some VOCs was 80∼100% in 15∼24 hours. In the initial step of phptocatalyst plasma reaction. Acetone and Nitromethane etc were detected. But they were completely oxidized to CO2 and H2O.

• 한국정보디스플레이학회:학술대회논문집
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• 2009.10a
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• pp.254-257
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• 2009

The crystallization and activated annealing effect of Si films using an excimer laser and a new CW blue laser are described comparing with furnace annealing (SPC) for the application of advanced TFTs and future applications. Currently, pulsed ELA is used extensively as a LTPS process on glass substrates as the efficiency is high in UV region for thin Si film of 40- 60 nm thickness. ELA enables extremely low resistivity for both n- and p-typed Si films. On the other hand, CW BLDA enables the smooth Si surface having arbitral grains from micro-grains to anisotropic huge grain structure only controlling its power density.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2000.04a
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• pp.125-128
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• 2000

ZnO thin films on silicon substrates have been deposited by pulsed laser deposition technique(PLD). A Nd:YAG laser was used with the wavelength of 355 nm. In order to investigate the effect of oxygen post-annealing treatment on the property of ZnO thin films, deposited film has been annealed at the substrate temperature of $440^{\circ}C$. After post-annealing treatment in the oxygen ambient, the stoichiometry of ZnO film has been characterized be improved which results in higher UV emission intensity of photoluminescence.

• Proceedings of the Korean Vacuum Society Conference
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• 2013.08a
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• pp.176.2-176.2
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• 2013

Property of optical diagnostics for pulse-discharged plasma in liquid and its biological applications to proteins are investigated by making use of high voltage Marx generator. The Marx generator has been consisted of 5 stages, where each charging capacitor is 0.5 ${\mu}F$, to generate a high voltage pulse with rising time of $1{\mu}s$. We have applied an input voltage of 6 kV to the each capacitor of 0.5 ${\mu}F$. High voltage pulsed plasma has been generated inside a polycarbonate tube by a single-shot operation, where the breakdown voltage is measured to be 7 kV, current of 1.2 kA, and pulse width of ~ 1 ${\mu}s$ between the two electrodes of anode-cathode whose material is made of tungsten pin, which are immersed into the liquids. We have investigated the emitted hydrogen lines for optical diagnostics of high voltage pulsed plasma. The emission line of 656.3 nm from $H-{\alpha}$ and 486.1 nm from $H-{\beta}$ have been measured by a monochromator. If we assumed that the focused plasma regions satisfy the local thermodynamic equilibrium conditions, the electron temperature and density of the high voltage pulsed plasma in liquid could be obtained by the Stark broadening of optical emission spectroscopy. For the investigation of the influence of pulsed plasma on biological proteins, we have exposed it onto the proteins such as hemoglobin and myoglobin. The structural changes in these proteins and their analysis have also been obtained by circular dichroism (CD) and ultraviolet (UV) visible spectroscopy.

• Journal of the Korean Society for Precision Engineering
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• v.27 no.10
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• pp.23-28
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• 2010

Resistance trimming and cutting processes of printed circuit board by making use of high power UV laser with nano-second pulse width have been proposed and investigated experimentally. Also laser-based application system with high flexibility and complex has been designed and adopted power controller, auto beam size control, auto-focusing and control program developed for ourselves. The function of each module shows that they can be reliable for industrial equipments. Resistance trimming method used a plunge and double cut process with $20{\mu}m$ spot size beam. Results show that double cut process is more effective to control resistance trimming in precision than plunge cut process.

• Journal of the Korean Society for Precision Engineering
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• v.27 no.2
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• pp.20-24
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• 2010

High speed cutting processes of rigid flexible printed circuit board by making use of high power UV laser with nano-second pulse width have been proposed and investigated experimentally. Also robust laser cutting system has been designed and developed in order to obtain a good cutting quality of rigid and flexible PCB with multi-layers (2-6 layers). Power controller module developed for ourselves is adapted to control the laser output power in the range less than 1%. The systems show the good performance of cutting speed, cutting width and cutting accuracy, respectively. Especially we have confirmed that the short circuit problem due to the carbonized contamination occurred in cross section of multi-layers by thermal effect of high power laser has been improved largely by using multi-pass cutting process with low power and high speed.

• 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.

• Proceedings of the Korean Vacuum Society Conference
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• 2010.08a
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• pp.207-207
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• 2010

Both ZnO and GaN have excellent physical properties in optoelectronic devices such as blue light emitting diode (LED), blue laser diode (LD), and ultra-violet (UV) detector. The ZnO/GaN heterostructure, which has a potential to achieve the cost efficient LED technology, has been fabricated by using radio frequency (RF) sputtering, pyrolysis, metal organic chemical vapor deposition (MOCVD), direct current (DC) arc plasmatron, and pulsed laser deposition (PLD) methods. Among them, the PLD system has a benefit to control the composition ratio of the grown film from the mixture target. A 500-nm-thick ZnO film was grown by PLD technique on c-plane GaN/sapphire substrates. The post annealing process was executed at some varied temperature between from $300^{\circ}C$ to $900^{\circ}C$. The morphology and crystal structural properties obtained by using atomic force microscope (AFM) and x-ray diffraction (XRD) showed that the crystal quality of ZnO thin films can be improved as increasing the annealing temperature. We will discuss the post-treatment effect on film quality (uniformity and reliability) of ZnO/GaN heterostructures.

• Journal of the Korean Ceramic Society
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• v.44 no.6 s.301
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• pp.303-307
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• 2007

Transparent In-doped zinc oxide (IZO) thin films are deposited with variation of pulsed DC power at Ar atmosphere on coming 7059 glass substrate by pulsed DC magnetron sputtering. A c-axis oriented IZO thin films were grown in perpendicular to the substrate. The optical transmittance spectra showed high transmittance of over 80% in the UV-visible region and exhibited the absorption edge of about 350 nm. Also, the IZO films exhibited the resistivity of ${\sim}10^{-3}{\Omega}\;cm$ and the mobility of ${\sim}6cm/V\;s$. Organic Light-emitting diodes (OLEDs) with IZO/N,N'-diphenyl-N, N'-bis(3-methylphenl)-1, 1'-biphenyl-4,4'-diamine (TPD)/tris (8-hydroxyquinoline) aluminum ($Alq_3$)/LiF/Al configuration were fabricated. LiF layer inserted is used as an interfacial layer to increase the electron injection. Under a current density of $100\;mA/cm^2$, the OLEDs show an excellent efficiency (9.4 V turn-on voltage) and a good brightness ($12000\;cd/m^2$) of the emission light from the devices. These results indicate that IZO films hold promise for anode electrodes in the OLEDs application.

• Proceedings of the KIEE Conference
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• 2006.10a
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• pp.46-47
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• 2006

Ga-doped ZnO nanowires have been synthesized by pulsed laser deposition (PLD) in furnace on gold coated (0001) sapphire substrates. The effect of repetition rate on structural and optical properties of Ga-doped ZnO nanowires are investigated. By controlling repetition rate, the diameter of nanowires is varied between about 60 and 100 nm, and the length of nanowires is varied between about 2 and 4 um. The X-ray diffraction (XRD) reveals the structural defects induced by the Ga doping. The room temperature photoluminescence (PL) spectra of Ga-doped ZnO nanowires show strong UV emission between 382.394 and 385.279 nm with negligible visible emission.