• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2000년도 영호남학술대회 논문집
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• pp.17-20
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• 2000

This paper describes on the fabrication and characteristics of hot-film type micro-flowsensors integrated with Pt-RTD's and micro-heaters on the Si substrate, in which MgO thin-films were used as medium layer in order to improve adhesion of Pt thin-films to $SiO_2$ layer, The MgO layer improved adhesion of Pt thin-films to $SiO_2$ layer without any chemical reactions to Pt thin-films under high annealing temperatures. In investigating output characteristics of the fabricated micro-flowsensors, the output voltages increased as gas flow rate and its conductivity increased due to increase of heat-loss from sensor to external. Output voltage was 82 mV at $N_2$ flow rate of 2000 seem/min, heating power of 1.2W.

• KIEE International Transactions on Electrophysics and Applications
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• 제4C권4호
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• pp.142-144
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• 2004

To use Poly-dimethylsiloxane (PDMS) for the electrokinetic flow channel, the PDMS surface must be modified to be hydrophilic. With $O_2$ plasma treatment, it is difficult to maintain hydrophilicity for more than one day. In this paper, we present the chemical modification of the PDMS surface using 2-Hydroxyethyl methacrylate (HEMA) to prolong hydrophilicity lifetime. The oxide radicals generated temporarily on the PDMS surface by $O_2$ plasma are grafted with HEMA. Once the PDMS samples have been grafted, they demonstrate improved hydrophilicity retainment and electroosmotic flow characteristics compared to the untreated PDMS and the oxidized PDMS following the $O_2$ plasma process. This phenomenon was verified by the contact angles, Fourier transform infrared (FTIR) spectra and electro osmotic flow rates observed for more than 300 hours.

• 한국세라믹학회지
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• 제52권2호
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• pp.137-139
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• 2015

In this study, we examined the influence of molten $KNO_3$ flow on mechanical properties and their deviation when a chemical toughening process was applied to soda lime silicate glass ($Na_2O-CaO-SiO_2$). $KNO_3$ melt flow was controlled using three methods: (1) glass tray rotation, (2) impeller stirring, and (3) natural convection. DOL and hardness were found to be enhanced by tray rotation because this rotation was able to maintain the concentration around the glass surface, in contrast to other methods. However, there did not appear to be a statistically significant difference in the 3-point bending strength for the three flow conditions due to the ground edge condition.

• 한국전기전자재료학회논문지
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• 제21권4호
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• pp.362-367
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• 2008

We have Manufactured the low-k dielectric interlayer fabricated by plasma enhanced chemical vapor deposition (PECVD), The thin film of SiOCH is studied correlation between components and Dielectric constant. The precursor was evaporated and introduced with the flow rates from 16 sccm to 25 sccm by 1sccm step in the constant flow rate of 60 sccm $O_2$ in process chamber. The chemical characteristics of SiOCH were analyzed by measuring FT/IR absorption lines and obtained each dielectric constant measuring C-V. Then compare respectively. ILD of BTMSM/$O_2$ could have low dielectric constant about $k\sim2$, and react sensitively. Also dielectric constant could be decreased by the effects of decreasing $CH_3$ and growing Si-O-Si(C) after annealing process.

• 한국분말재료학회지
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• 제11권1호
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• pp.50-54
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• 2004

Nanoparticles of iron oxides have been prepared by the levitational gas condensation (LGC) method, and their structural and magnetic properties were studied by XRD, TEM and Mossbauer spectroscopy. Fe clusters were evaporated from a surface of the levitated liquid Fe droplet and then condensed into nanoparticles of iron oxide with particle size of 14 to 30 nm in a chamber filled with mixtures of Ar and $O_2$ gases. It was found that the phase transition from both $\gamma$-$Fe_2O_3$ and $\alpha$-Fe to $Fe_3O_4$, which was evaluated from the results of Mossbauer spectra, strongly depended on the $O_2$ flow rate. As a result, $\gamma$-$Fe_2O_3$ was synthesized under the $O_2$ flow rate of 0.1$\leq$$Vo_2$(Vmin)$\leq$0.15, whereas $Fe_3O_4$ was synthesized under the $O_2$, flow rate of 0.15$\leq$$Vo_2$(Vmin)$\leq$0.2.

• 반도체디스플레이기술학회지
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• 제11권4호
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• pp.25-30
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• 2012

In this study, we have investigated the effect of the substrate temperature and oxygen flow rate on the characteristics of IZO thin films for the organic light emitting diodes (OLED) devices. For this purpose, IZO thin films were deposited by RF magnetron sputtering at room temperature and $300^{\circ}C$ with various $O_2$ flow rate. In order to investigate the influences of the oxygen, the flow rate of oxygen in argon mixing gas has been changed from 0.1sccm to 0.5sccm. IZO thin films deposited at room temperature show amorphous structure, whereas IZO thin films deposited at $300^{\circ}C$ show crystalline structure having an (222) preferential orientation regardless of $O_2$ flow rate. The electrical resistivity of IZO film increased with increasing flow rate of $O_2$ under $Ar+O_2$. The change of electrical resistivity with increasing flow rate of $O_2$ was mainly interpreted in terms of the charge carrier concentration rather than the charge carrier mobility. The electrical resistivity of the amorphous-IZO films deposited at R.T. was lower than that of the crystalline-IZO thin films deposited at $300^{\circ}C$. The change of electrical resistivity with increasing substrate temperature was mainly interpreted in terms of the charge carrier mobility rather than the charge carrier concentration. All the films showed the average transmittance over 83% in the visible range.

• 한국대기환경학회지
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• 제8권1호
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• pp.84-91
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• 1992

Hydrodesulfurization of thiophene was studied over $Ni-W/TiO_2-ZrO_2$ catalysts in a fixed bed flow reactor. The ranges of experimental conditions were at the temperatures between 200$^\circ$C and 360$^\circ$C, the pressures between 20 X $10^5$ Pa. The catalysts were reduced with the flow of 10 L/hr of $H_2$ at the temperature of 350$^\circ$C. It was found that $TiO_2-ZrO_2$ supported catalysts had similar activity to $\gamma-Al_2O_3$ supported. The largest surface areas and the highest acidity occured as the binary oxides were mixed with equal molar ratios. The HDS increased with increasing temperatures, pressures and contact times.

• 대한기계학회논문집B
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• 제31권1호
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• pp.16-20
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• 2007

In this paper, convective heat transfer and flow characteristics of $Al_2O_3$ nanoparticles suspended in water flowing through uniformly heated tubes are experimentally investigated under laminar flow regime. The heat transfer coefficient and the pressure drop of nanoparticles suspended in water are experimentally presented according to the pumping power. In addition, the heat transfer coefficient and the pressure drop of $Al_2O_3$ nanoparticles suspended in water are compared with those of pure water under the fixed pumping power. It is shown that the heat transfer coefficient of $Al_2O_3$ nanofluids with 0.1% volume fraction is enhanced by about 12% although the increment of the pressure drop of those is 4% compared with those of pure water.

• KSBB Journal
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• 제13권5호
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• pp.477-482
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• 1998

A biosensor with PZT piezoelectric ceramic crystal was developed for the detection of formaldehyde gas. Poled PZT piezoelectric ceramic disk was made from ZrO2, TiO2 and Nb2O5, together with the addition of PbO and polyvinyl alcohol, through various processes of mixing, calcination drying, crushing, forming, sintering, polishing, ion coating and poling. Oscillator circuit of sensor was made of operational amplifier(AD811AN). Formaldehyde dehydrogenase was immobilized onto a piezoelectic ceramic crystal, together with the cofactors, reduced glutathione and nicotinamide adenine dinucleotide. The effect of flow rate on the sensitivity was determined by varing the flow rate of carrier gas from 24.7mL/min to 111.7mL/min through detector cell. The results indicated that as the flow rate was increased, the recovery rate was increased. And a significant increase in the sensitivity was observed in enhanced flow rate of carrier gas. Frequency difference(ΔF) of immobilized PZT piezoelectic disk increased proportionally to the concentration gas and reproduced to repeated exposures of formaldehyde gas(28ppm, Δ68Hz).

• 대한전기학회:학술대회논문집
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• 대한전기학회 1999년도 하계학술대회 논문집 G
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• pp.3319-3321
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• 1999

Pt-RTD and Micro Heater was fabricated by using MgO as medium layer in order to improve adhesion of Pt thin-films to $SiO_2$ layer, MgO layer improved adhesion of Pt thin-films to $SiO_2$ layer without any chemical reactions to Pt thin-films under high annealing temperatures, In the analysis of properties of Pt-RTD, TCR value had 3927 $ppm/^{\circ}C$ and liner in the temperature range of $25-400^{\circ}C$. The temperature of Pt micro-heater had up to $400^{\circ}C$ with 1.5watts of the heating power. In investigating output characteristics of flow sensors output voltages increased as gas flow rate and its conductivity increased due to increase of heat-loss from sensor to external. Output voltage was 82 mV at $N_2$ flow rate of 2000sccm, heating power of 1.2W.