• Applied Science and Convergence Technology
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• v.25 no.6
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• pp.145-148
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• 2016

This paper, Al-doped ZnO(AZO) thin films for application as transparent conducting oxide films were deposited on the Corning glass substrate by using RF magnetron sputtering system. The effects of various Argon gas flow rates on optical and electrical characteristics of AZO films were investigate sputtering method. The Carrier Concentration is enhanced as Ar gas rate increases, and also the oxygen vacancy concentration. The figure of merit obtained in this study means that AZO films which deposited Ar gas rate of 75 sccm have the highest Carrier concentration and Hall mobility, which have the highest photoelectrical performance that it could be used as transparent electrodes.

• Journal of the Korean Vacuum Society
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• v.17 no.2
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• pp.130-137
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• 2008

$La_{0.7}Sr_{0.3}MnO_3$ films were deposited on $SiO_2$/Si and Si substrates annealed at $350^{\circ}C$ by rf magnetron sputtering. The oxygen gas flow rates were varied as 0, 40, and 80 sccm. Without post annealing process, $La_{0.7}Sr_{0.3}MnO_3$ thin films on $SiO_2$/Si and Si substrates were polycrystalline with (100), (110), and (200) growth planes. The grain size of $La_{0.7}Sr_{0.3}MnO_3$ thin films was increased with increasing oxygen gas flow rate. The sheet resistance of $La_{0.7}Sr_{0.3}MnO_3$ thin films was decreased with oxygen flow rate due to the increased grain size which induced a reduction of grain boundary. TCR (temperature coefficient of resistance) values of $La_{0.7}Sr_{0.3}MnO_3$ thin films were obtained from -2.0% to -2.2%.

• Journal of the Korean Vacuum Society
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• v.10 no.2
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• pp.182-188
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• 2001

Thin films of $SiO_xC_y$ deposited by means of PECVD(plasma enhanced chemical vapor deposition) using HMDSO(hexamethyldisiloxane)/$O_2$ were characterized. The effects of deposition conditions such as RF power, oxygen flow rate and hydrogen flow rate on the chemical bond structure, atomic composition, surface roughness and wear characteristics of the films were investigated by means of FTIR, XPS, AFM and Hazemeter. The deposition rate of $SiO_xC_y$ was greater than 100 nm/min, which is relatively high rate. The XPS results showed that the carbon content in a deposited film was lower than that of previous studies where different organosilicone materials were used. The optimum wear resistance was attained when RF power was 200 Watt and oxygen flow rate was 100 sccm. This study implies that the $HMDSO/O_2$ system is effective in forming a film with a lower carbon content and good abrasion resistance.

• Korean Journal of Materials Research
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• v.17 no.2
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• pp.61-67
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• 2007

The magnetron reactive sputtering was adopted to deposit CuO buffer layers on the polyimide surfaces for increasing the adhesion strength between Cu thin films and polyimide, varying $O_2$ gas flow rate from 1 to 5 sccm. The CuO oxide was formed through all the $O_2$ gas flow rates of 1 to 5 sccm, showing the highest value at the 3 sccm $O_2$ gas flow rate. The XPS analysis revealed that the $Cu_2O$ oxide was also formed with a significant ratio during the reactive sputtering. The adhesion strength is mainly dependent on the amount of CuO in the buffer layers, which can react with C-O-C or C-N bonds on the polyimide surfaces. The adhesion strength of the multi-layered Cu/buffer layer/polyimide specimen decreased linearly as the heating temperature increased to $300^{\circ}C$, even though there showd no significant change in the chemical state at the polyimide interface. This result is attributed to the decrease in surface roughness of deposited copper oxide on the polyimide, when it is heated.

• The KSFM Journal of Fluid Machinery
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• v.1 no.1 s.1
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• pp.41-48
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• 1998

This study was carried out to investigate the effect of design parameters on the volume flow-rate and the noise level and to finally find the optimal design variables. Eighteen cross-flow fans were designed by the method of orthogonal array, and the flow-rate and the noise level were measured. These data were analyzed by the neural network system. The effects of eight design variables(scroll exit angle, scroll arc length et al.) on the fan performance and the noise level were valuated and discussed. This experiment shows that the design solutions suggested by neural network system may increase its volume flow-rate and reduce noise simultaneously.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1989.06a
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• pp.66-69
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• 1989

After reviewing previous work done on two piezoelectric thin films(PZT, ZnO), ZnO thin piezofim of 1-3UM is fabricated by sputtering on the different substrates(i. e., P+Si/N-Si, SiO2/P+Si/ N-Si, Al/SiO2/ P+Si/ N+Si). The result shows that ZnO piezofilm on the Al has the best c-axis orientation. One of applications for the ZnO piezofilm as an microvalve to control liquid flow is introduced, and which can be controlled electrically and remotely.

• Journal of computational fluids engineering
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• v.5 no.1
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• pp.33-42
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• 2000

The LiBr-H₂O absorption process on a horizontal tube has been analyzed numerically. The flow field, which was calculated in the authors' previous study by solving the fully elliptic Navier-Stokes equations with accurate free-surface-tracking method, is used to solve the temperature and concentration distributions in the absorption film. With the assumption that the absorbent is linear, calculations have been made for various inlet temperature and flow-rate conditions. For low inlet temperature, the absorption rate is large in the upstream region but the mean temperature also increases and as a result the absorption decreases as the film flows to downstream while high-inlet-temperature case does the opposite. The difference in the absorption rate due to the inlet temperature change becomes smaller in the downstream than that in the upstream. For large flow rate, the heat transfer to the wall becomes poor due to the thick film and so does the absorption rate. The analyses have also been carried out for multiple tube arrangement and the results show that the absorption rate converges after a few tube rows.

• Proceedings of the KIEE Conference
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• 1997.11a
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• pp.609-611
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• 1997

Pt thin films flow sensors were fabricated by using aluminum oxide films as medium layer and their characteristics were investigated after annealing at $600^{\circ}C$ for 60min. Aluminum oxide improved adhesion of Pt thin films to $SiO_2$ layer without any chemical reactions to Pt thin films under high annealing temperatures. Output voltages increased as gas flow rate and gas conductivity increased because heat loss of heater, which was integrated with a sensing resistor in the flow sensor, increased. Output voltage of flow sensor fabricated on membrane structure was 101mV at $O_2$ flow rate of 2000sccm, heating power of 0.8W while flow sensor fabricated on Si substrate without membrane had output voltage of 78mV under the same conditions.

• Journal of Environmental Health Sciences
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• v.23 no.4
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• pp.127-132
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• 1997

The characteristics of the ozone treatments of phenol were studied in a laboratory scale wastewater treatment system. The ozone treatment of wastewater was carried out in a batch-type reactor. The initial pH of wastewater(7-10), volumetric flow rate(1-2l/min) and ozone concentration(20~30 mg/l) of aerating gas were considereal as experimental variables in the ozone treatment. Phenol was decomposed easily by the ozone in a batch treatment, where the rate determining step was the COD removal that is decomposition of intermediates formed by the ozonation of phenol. Phenol decomposition and COD removal could be expressed by the first order reaction for the phenol concentration and COD, respectively. Rate constants of phenol decomposition and COD removal increased with the initial pH, volumetric flow rate and ozone concentration of aeration gas. Under the present experimental condition, their relationships could be given by for the phenol decomposition $k'=4.46\times 10^{-9}[pH]_o ^{3.94}[O_3]^{1.42}Q_{O3}^{1.57}$ for the COD removal $k=2.46\times 10^{-10}[pH]_o ^{5.19}[O_3]^{1.15}Q_{O3}^{1.19}$

• Journal of the Korean Electrochemical Society
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• v.9 no.2
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• pp.77-83
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• 2006

Anodic overpotential has been investigated with gas composition changes in a $100cm^2$ class molten carbonate fuel cell. The overpotential was measured with steady state polarization, reactant gas addition (RA), inert gas step addition (ISA), and electrochemical impedance spectroscopy (EIS) methods at different anodic inlet gas compositions, i.e., $H_2:CO_2:H_2O=0.69:0.17:0.14\;atm\;and\;H_2:CO_2:H_2O=0.33:0.33:0.33\;atm$, at a fixed $H_2$ flow rate. The results demonstrate that the anodic overpotential decreases with increasing $CO_2\;and\;H_2O$ flow rates, indicating the anode reaction is a gas-phase mass-transfer control process of the reactant species, $H_2,\;CO_2,\;and\;H_2O$. It was also found that the mass-transfer resistance due to the $H_2$ species slightly increases at higher $CO_2\;and\;H_2O$ flow rates. EIS showed reduction of the lower frequency semi-circle with increasing $H_2O\;and\;CO_2$ flow rate without affecting the high frequency semi-circle.