• Journal of the Korean Ceramic Society
• /
• v.37 no.6
• /
• pp.537-544
• /
• 2000

Thin-film humidity sensor which TiO2, ZrO2, or CeO2 was added to MgCr2O4-based materials, respectively, were fabricated on the alumina substrate by using a resistant-heating evaporator. Thin films were approximately 2${\mu}{\textrm}{m}$ in grain size and shwoed porous microstructures. The resistance of the sensor decreased with increasing the relative humidity and the MgCr2O4-TiO2 sensor had the best humidity-sensing characteristics (linearity in relative humidity versus resistance).

• Journal of the Korean Ceramic Society
• /
• v.31 no.5
• /
• pp.477-484
• /
• 1994

The yttria stabilized zirconia(YSZ) thin films for solid oxide fuel cell (SOFC) were fabricated by an electrochemical vapor deposition(EVD) technique using YCl3+ZrCl4+H2O gas system. The YSZ films were deposited under reduced pressure at the temperature of 1000~120$0^{\circ}C$ on the porous alumina substrates. The deposition rate, chemical composition and growth morphology were investigated by SEM, XRD, EDS. The growth rates of the films obeyed a parabolic rate law, representing that the growing process is controlled by an electrochemical transport through the YSZ film. The Y2O3 content of the films was about 10 mol%, equal to the composition of metal chloride reactant gases, approximately. The YSZ films were highly dense, the growing features showed columnar structure and surface morphologies were changed with the EVD conditions.

• The Transactions of The Korean Institute of Electrical Engineers
• /
• v.58 no.12
• /
• pp.2474-2479
• /
• 2009

This paper presents an atmospheric microplasma-jet device for bio~medical application. The microplasma-jet device consists of four components; a thin Ni anode, porous alumina insulator, a stainless steel cathode and an aluminum case. The anode has 8 holes, and hole diameter and depth are $200 {\mu}m$ and $60 {\mu}m$, respectively. The discharge test was performed in atmospheric pressure using nitrogen gas and AC voltage at the optimum gas flow rate of 4 Vmin. The plasma-jet is ejected stably for the input voltage ranging from 5.5 to $9.5 kV_{p-p}$. The plasma becomes dense as the input voltage increases, which was verified by the hydrophilicity change of PMMA surface treated by the plasma. The temperature increasement of the aluminum film exposed to plasma-jet illustrates that the micro plasma-jet device is feasible for bio-medical application.

• Proceedings of the KIEE Conference
• /
• 1999.11d
• /
• pp.1011-1014
• /
• 1999

An on-board monitoring system for an automobile emission gas has a test chamber remote from the automobile's engine exhaust gas stream: apparatus for supplying the chamber with sampled exhaust gases. A single hydrocarbon sensor exposed to the exhaust gas in the chamber to render a signal responsive to the hydrocarbon. The conductive ions in emission gas was checked by the HC sensor in test chamber. A preferred application includes hydrocarbons in an automotive exhaust gas stream by exposing a transition porous alumina($Al_{2}O_{3}$) ceramic based sensor to the same exhaust gas stream. By combining the electrical signal, a measure of hydrocarbons can be provided.

• Journal of the Korean Ceramic Society
• /
• v.43 no.4 s.287
• /
• pp.220-223
• /
• 2006

BLT nanotubes were synthesized by using simple and convenient method template-wetting process. Porous alumina membranes were prepared by 2 step anodic oxidation as the template. To improve wetting properties and make low surface energy, BLT solution was mixed with polymer. Polymer was removed completely during annealing. After completely etching the template in 30 wt% KOH solution, we demonstrate that BLT nanotubes with a diameter of 200 nm can be fabricated. Grain growth process of BLT nanotubes during baking, and furnace annealing was examined by FE-SEM and XRD.

• Bulletin of the Korean Chemical Society
• /
• v.29 no.4
• /
• pp.758-760
• /
• 2008

Nanoporous AAO (Anodic Aluminum Oxide) membranes have many advantages as a template for variety of magnetic materials. Materials can be embedded into the pores by electrodeposition, sputtering or magnetic-field-assisted infiltration of magnetic nanoparticles. This work focuses on the fabrication of the magnetic structures in the AAO templates by electrodeposition. Our method allows the controlled growth of Co nanostructures within the porous alumina membrane in the form of dots, rods and long wires. The shape of Co nanostructures has been investigated by field emission scanning electron microscope (FESEM). The magnetic hysteresis loops of Co nanostructures were measured using SQUID at 5 K and 300 K. The magnetic properties of the Co nanostructures are proportional to their aspect ratios and can be controlled by changing the aspect ratios.

• The Korean Journal of Ceramics
• /
• v.1 no.4
• /
• pp.219-223
• /
• 1995

Ceramic membranes of the supported $TiO_2-CeO_2$ were prepared by dip-coating method on an $\alpha-Al_2O_3$ porous substrate. The mean pore diameter of an alumina support was 0.125 um. The mean particle diameter of $TiO_2-CeO_2$ top layer varied with firing temperature and ranged from 20 to 85 nm. The thermal stability of the composite membranes was studied from their surface microstructure after calcination at $600-900^{\circ}C$. The supported $TiO_2-CeO_2$ composite membranes exhibited much higher heat resistance than the $TiO_2$ membrane.

• Proceedings of the KSME Conference
• /
• 2004.04a
• /
• pp.144-149
• /
• 2004

Porous anodic alumina has been used widely for corrosion protection of aluminum surfaces or as dielectric material in micro-electronics applications. It exhibits a homogeneous morphology of parallel pores which can easily be controlled between 10 and 400nm. It has been applied as a template for fabrication of the nanometerscale composite. In this study, mechanical properties of the AAO structures are measured by the nano indentation method. Nano indentation technique is one of the most effective method to measure the mechanical properties of nano-structures. Basically, hardness and elastic modulus can be obtained by the nano-indentation. Using the nano-indentation method, we investigated the mechanical properties of the AAO structure with different size of nano-holes. In results, we find the hole effect that changes the mechanical properties as size of nano hole.

• Proceedings of the Membrane Society of Korea Conference
• /
• 2003.07a
• /
• pp.21-24
• /
• 2003

Methane steam reforming (MSR) was studied in a membrane reactor (MR) with a Pd-based and a porous alumina membranes. MRs showed methane conversion higher than that foresaw by the thermodynamic equilibrium for a traditional reactor (TR). Silica membranes prepared at KRICT were characterized with permeation tests on single gases ($N_2$, $H_2$ and $CH_4$). These silica membranes can be also used for high temperature applications such as $H_2$ separation $CO_2$ hydrogenation for methanol production is another reaction where $H_2O$ selective removal can be performed with these silica membranes.

• Journal of Surface Science and Engineering
• /
• v.50 no.6
• /
• pp.427-431
• /
• 2017

Anodic aluminum oxide (AAO) film has recently attracted much attention as a key material for the fabrication of various nanostructures. A control of anodizing voltage (U) was employed to render different anodic aluminum oxide (AAO) nanostructures with pore diameter ($D_p$) and interpore distance ($D_{int}$) in oxalic acid. In this work, we study the effect of stepwise modulation of anodizing voltages on the shape and dimension of porous structures along the vertical direction and demonstrate the fabrication of hierarchical layers of systematically controlled three-dimensional (3D) pore profile.