• Journal of the Korean Ceramic Society
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• v.41 no.7
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• pp.518-527
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• 2004

In this study, SiC whiskers were grown in porous alumina substrate in order to enhance the filtering efficiency, performance, and durability by controlling pore morphology. This experiment was performed by Chemical Vapor Infiltration (CVI) in order to obtain the whiskers on the inside of pores as well as on the surface of porous the A1$_2$O$_3$ substrate. The deposition behavior was changed remarkably with the deposition position, temperature, and input gas ratio. First, the mean diameter of whisker was decreased as the position of observation moved into the inside of substrate due to the reactant gas depletion effect'. Second, the deposition temperature caused the changes of the deposition type such as debris, whiskers and films and the change in morphology affect the various properties. When SiC films were deposited. the gas permeability and the specific surface area decreased. However, the whisker showed the opposite result. The whiskers increase not only the specific surface area and minimizing pressure drop but also mechanical strength. Therefore it is expected that the porous alumina body which deposited the SiC whisker is the promising material for the filter trapping the particles.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2016.11a
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• pp.115.1-115.1
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• 2016

Electrochemical anodization has been interested due to its useful way for the nano-scale architecture of metal oxides obtained from a metal substrate. By using this method, it is easy to control the morphology of the oxide materials by controlling electrochemical conditions. Among oxide materials obtained from the transition metals such as Ti, V, W, etc., in this paper, the morphological study of anodized $TiO_2$ was employed at various voltage conditions in fluoric based electrolyte, and the effects of applied voltage (sweep rate and retention time) on the tube morphologies were investigated. Furthermore, by using anodization of tungsten substrate (W), we fabricated the porous structure of $WO_3$ and provided merits of tailored structure for the hybridization of inorganic and organic materials as electrochromic (EC) applications. The hybrid porous $WO_3$ shows multi-chromic properties during the EC reactions at specific voltage conditions. From these results, the anodization process with tailoring nano-structure is one of the promising methods for EC applications.

• Journal of Environmental Science International
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• v.5 no.1
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• pp.61-69
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• 1996

The combined wastewater of municipal landfill leachate and municipal sewage was treated using several sets of bench-scale aerated circulating system including porous media. Investigated items in this experiment were the dominant protozoa and metazoa in this system, the variation of microfauna relationship between operating condition and dominant genera. Also considered the factors determining dominant genera and their role. The outcome of this research is as follows; 1. Aspidisca, Vorticella, Truhellophyllum, Lecane, Philodina, Cyclops were mainly appeared prior to combinding leachate, while Trachelocerca, Bodo, Glaucoma were the dominant genera after combinding leachate. 2. As to metazoa, Nematode and Philodina were not influenced by 5oA leachate mixing ratio, meanwhile Crustacea has high sensitivity for increased leachate mixing ratio and it was not appeared in 5% leachate mixing ratio. 3. The appropriate treatability could'nt be expected at the above 10% leachate mixing ratio. Especially, in the condition of 20% leachate mixing ratio, all of the microfauna were affected damage seriously on their existence. Meanwhile hydraulic retention time, substrate loading rate and slut자e production rate didn't give notable influence on increasing the number of microfauna. 4. As to protozoa, saprozoic and holozoic species were appeared commonly and polysaprobic species were dominent. 5. Filamentous organsms were nearly not affected by leachate mixing. It seems that they could live without any trouble at the 10% leachate mixing ratio, if the substrate is sufficient. 6. Diversity of microfauna had a reducing trernd as the sewage was mixed with leachate.

• The Korean Journal of Ceramics
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• v.5 no.2
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• pp.131-136
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• 1999

Yttria stabilized zirconia(YSZ) films were deposited on porous NiO substrates and quartz plates by the thermal CVD using $ZrCl_4, YCl_3$ as precursors, and $O_2$ as a reactive gas at atmospheric pressure. The evaporation temperature of $ZrCl_4$ was varied from $250^{\circ}C$ to $550^{\circ}C$ while the temperatures of $YCl_3$ and the substrate were varied from $1000^{\circ}C$ to $1030^{\circ}C$. As the evaporation temperature of $ZrCl_4$ increased, the deposition rate of $ZrO_2$ decreased, contrary to our expectation. As a result of the decreased deposition rate of $ZrO_2$, the yttria content increase. The high evaporation temperature of $ZrCl_4$ makes the well-faceted crystal while the low evaporation temperature leads to the cauliflower-shaped structure. The dependence of the evaporation temperature on the growth rate and the morphological evolution was interpreted by the charged cluster model.

• Korean Journal of Chemical Engineering
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• v.36 no.6
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• pp.975-980
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• 2019

Infrared (IR) spectroscopy is a powerful technique for observing organic molecules, as it combines sensitive vibrational excitations with a non-destructive probe. However, gaseous volatile compounds in the air are challenging to detect, as they are not easy to immobilize in a sensing device and give enough signal by themselves. In this study, we fabricated a thin nanocrystalline metal-organic framework (nMOF) film on a surface plasmon resonance (SPR) substrate to enhance the IR vibration signal of the gaseous volatile compounds captured within the nMOF pores. Specifically, we synthesized nanocrystalline HKUST-1 (nHKUST-1) particles of ca. 80 nm diameter and used a colloidal dispersion of these particles to fabricate nHKUST-1 films by a spin-coating process. After finding that benzene was readily adsorbed onto nHKUST-1, an nHKUST-1 film deposited on a plasmonic Au substrate was successfully applied to the IR detection of gaseous benzene in air using surface-enhanced IR spectroscopy.

• The Journal of Advanced Prosthodontics
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• v.6 no.4
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• pp.285-294
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• 2014

PURPOSE. The purpose of this study was to evaluate the properties of a porous zirconia scaffold coated with bioactive materials and compare the in vitro cellular behavior of MC3T3-E1 preosteoblastic cells to titanium and zirconia disks and porous zirconia scaffolds. MATERIALS AND METHODS. Titanium and zirconia disks were prepared. A porous zirconia scaffold was fabricated with an open cell polyurethane disk foam template. The porous zirconia scaffolds were coated with ${\beta}$-TCP, HA and a compound of ${\beta}$-TCP and HA (BCP). The characteristics of the specimens were evaluated using scanning electron microscopy (SEM), energy dispersive x-ray spectrometer (EDX), and x-ray diffractometry (XRD). The dissolution tests were analyzed by an inductively coupled plasma spectrometer (ICP). The osteogenic effect of MC3T3-E1 cells was assessed via cell counting and reverse transcriptase-polymerase chain reaction (RT-PCR). RESULTS. The EDX profiles showed the substrate of zirconia, which was surrounded by the Ca-P layer. In the dissolution test, dissolved $Ca^{2+}$ ions were observed in the following decreasing order; ${\beta}$-TCP > BCP > HA (P<.05). In the cellular experiments, the cell proliferation on titanium disks appeared significantly lower in comparison to the other groups after 5 days (P<.05). The zirconia scaffolds had greater values than the zirconia disks (P<.05). The mRNA level of osteocalcin was highest on the non-coated zirconia scaffolds after 7 days. CONCLUSION. Zirconia had greater osteoblast cell activity than titanium. The interconnecting pores of the zirconia scaffolds showed enhanced proliferation and cell differentiation. The activity of osteoblast was more affected by microstructure than by coating materials.

• Journal of Powder Materials
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• v.25 no.1
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• pp.7-11
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• 2018

In this study, we synthesize tungsten oxide thin films by electrodeposition and characterize their electrochromic properties. Depending on the deposition modes, compact and porous tungsten oxide films are fabricated on a transparent indium tin oxide (ITO) substrate. The morphology and crystal structure of the electrodeposited tungsten oxide thin films are investigated by scanning electron microscopy (SEM) and X-ray diffraction (XRD). X-ray photoelectron spectroscopy is employed to verify the chemical composition and the oxidation state of the films. Compared to the compact tungsten oxides, the porous films show superior electrochemical activities with higher reversibility during electrochemical reactions. Furthermore, they exhibit very high color contrast (97.0%) and switching speed (3.1 and 3.2 s). The outstanding electrochromic performances of the porous tungsten oxide thin films are mainly attributed to the porous structure, which facilitates ion intercalation/deintercalation during electrochemical reactions.

• Journal of Convergence for Information Technology
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• v.9 no.5
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• pp.158-164
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• 2019

Recently many studies to reduce the noise of dental hand piece which generate inevitably mechanical sound to offend to the ear of a patient have been spotlighted. Generally, methods of adding a sound absorbing material inside the exhaust valve, air pump of machine or automobile are widely reported as optimal way to reduce the mechanical noise. In this paper we studied a new UV laser aided manufacturing of micro-porous structure of EPP substrate and applied dental hand piece to improve the efficiency of sound absorption. A lot of micro-sized pores were fabricated with UV laser processing on the surface of sliced EPP substrate. From fundamental experiments, more high-performance of micro-porous EPP substrate has finally demonstrated for sound-absorbing structure of the micro muffler inside dental hand piece, which actually has the excellent potential to apply a lot of potable machine.

• Journal of Hydrogen and New Energy
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• v.24 no.3
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• pp.230-236
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• 2013

In this study, successive coating and co-sintering techniques have been used to fabricate LSM/GDC based cathode supported direct carbon fuel cells. The porous LSM/GDC cathode substrate, dense, thin and crack free GDC and ScSZ layers as bi-layer electrolyte, and a porous Ni/ScSZ anode layer was obtained by co-firing at $1400^{\circ}C$. The porous structure of LSM/GDC cathode substrate, after sintering at $1400^{\circ}C$, was obtained due to the presence of GDC phase, which inhibits sintering of LSM because of its higher sintering temperature. The electrochemical characterization of assembled cell was carried out with air as an oxidant and carbon particles in molten carbonate as fuel. The measured open circuit voltages (OCVs) were obtained to be more than 0.99 V, independent of testing temperature. The peak power densities were 116, 195 and $225mWcm^{-2}$ at 750, 800 and $850^{\circ}C$, respectively.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.40 no.5
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• pp.285-289
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• 2003

This paper proposes a 10 ${\mu}{\textrm}{m}$ thick oxide air-bridge structure which can be used as a substrate for RF circuits. The structure was fabricated by anodic reaction, complex oxidation and rnicrornachining technology using TMAH etching. High quality films were obtained by combining low temperature thermal oxidation (50$0^{\circ}C$, 1 hr at $H_2O$/O$_2$) and rapid thermal oxidation (RTO) process (105$0^{\circ}C$, 2 min). This structure is mechanically stable because of thick oxide layer up to 10 ${\mu}{\textrm}{m}$ and is expected to solve the problem of high dielectric loss of silicon substrate in RF region. The properties of the transmission line formed on the oxidized porous silicon (OPS) air-bridge were investigated and compared with those of the transmission line formed on the OPS layers. The insertion loss of coplanar waveguide (CPW) on OPS air-bridge was (about 1 dB) lower than that of CPW on OPS layers. Also, the return loss of CPW on OPS air-bridge was less than about - 20 dB at measured frequency region for 2.2 mm. Therefore, this technology is very promising for extending the use of CMOS circuitry to higher RF frequencies.