• KSBB Journal
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• v.17 no.1
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• pp.54-58
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• 2002

Curdlan gel containing various hydrophobic materials was prepared. The homogenized suspension of curdlan and hydrophobic materials was healed at $100^{\circ}C$. The curdlan gel can contain hydrophobic material up to 27%(v/v). When gel was compressed, only water in the gel was removed. When immersed in water, the dried gel absorbed water and became the original wet gel. The syneresis of gel decreased with the concentration of hydrophobic material added. DHA content of dried gel was about 90%. $\beta$-cyclodextrin inclusion complexes containing DHA were prepared with addition of water and ethanol. X-ray diffractograms of complexes showed a specific peak at 7-$8^{\circ}C$ and FT-IR spectrum of complex showed a specific C=O peak at $1745\textrm{cm}^{-1}$. Inclusion complex containing DHA was microcapsulated with curdlan and pullulan.

• Journal of the Korean Wood Science and Technology
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• v.45 no.2
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• pp.139-146
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• 2017

This study was conducted to develop a new drying technology in order to quickly and massively dry bamboo tubes without crack and check. The bamboo tubes with the diameter of 45 mm - 68 mm had been impregnated in the solution of PEG-1000, and then were dried under room temperature and high temperature, respectively. The cracks occurred on all control specimens while no cracks were found on PEG treated specimens during drying at room temperature due to effect of PEG restraining the circumferential shrinkage of bamboo tube. But the drying period of this method was too long (200 days) compared to 10 hours of kiln drying. During fast high temperature drying, cracks occurred on all control specimens, but no cracks were found on PEG treated specimens, which could be accounted for more solidified PEG due to higher drying temperature and faster drying rate, and the tension set formed on the surface of bamboo tube in the early stage of drying owning to high drying temperature and low relative humidity. Thus, it is advised that PEG treated bamboo tube should be fast dried at high temperature in order to not only prevent crack or check in short drying period but also increase the dimensional stability of the products made of bamboo tubes.

• Korean Journal of Metals and Materials
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• v.48 no.5
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• pp.401-409
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• 2010

This study was performed to develop an antibacterial film that can be dried at room temperature. A nanosized TiO$_2$ particle-dispersed solution was prepared by the hydrothermal treatment of peroxo-titanic acid at 160${^{\circ}C}$ for 4h. The binder was synthesized through the hydrolysis and condensation reactions of TEOS (10cc) and GPTS (3.5cc) in the mixture of H$_2$O (30cc) and EtOH (30cc). The synthesized binder was mixed with 0.1 M of TiO$_2$ solution in a volume ratio of binder/TiO$_2$ solution=0.25~0.5. The glass substrate was coated after using the dip coating method, which was then followed by drying for over 2h at room temperature. Although the TiO$_2$ particles did not chemically-bond to the binder, the coating layer strongly adhered to the substrate and displayed good antibacterial properties.

• Journal of Forest and Environmental Science
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• v.26 no.2
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• pp.131-136
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• 2010

In an effort to evaluate the qualities of the unused woods designed for art materials, Yellow pine, Pitch pine, Suwon poplar, Platanus and Cherry grown in Korea has been investigated in the study. Physical and mechanical properties such as density, hardness, roughness, and abrasion of the woods were examined. Among the five species, Cherry wood showed the highest density in green, air-dried and oven-dried conditions. Hardness of Cherry wood was higher than those of Suwon poplar and Platanus. In softwoods, Pitch pine showed greater hardness than Yellow pine. Yellow pine and Platanus had the highest values of wood surface roughness. Abrasion value of cross, radial and tangential sections was the highest in Yellow pine and Suwon poplar. It has been concluded from the experiment that physical and mechanical properties such as density, hardness, roughness, and abrasion of the woods can be used as an indicator of the suitability for woodcraft material.

• Journal of the Korean institute of surface engineering
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• v.50 no.3
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• pp.198-205
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• 2017

Thermal dissipation was investigated for poly methyl methacrylate (PMMA) composite films containing graphite and multi wall carbon nanotube(CNT) powders as filler materials. After mixing PMMA with fillers, solvent, and dispersant, the pastes were prepared by passing through a three roll mill for three times. The prepared pastes were coated $15{\sim}40{\mu}m$ thick on a side of 0.4 mm thick aluminium alloy plate and dried for 30 min at $150^{\circ}C$ in an oven. The content of fillers in dried films was varied as 1, 2, and 5 weight % maintaining the ratio of graphite and CNT as 1:1. Raman spectra from three different samples exhibited D, G and 2D peaks, as commonly observed in graphite and multi wall CNT. Among those peaks, D peak was prominent, which manifested the presence of defects in carbon materials. Thermal emissivity values of three samples were measured as 0.916, 0.934, and 0.930 with increasing filler content, which were the highest ever reported for the similar composite films. The thermal conductivities of three films were measured as 0.461, 0.523, and $0.852W/m{\cdot}K$, respectively. After placing bare Al plate and film coated samples over an opening of a polystyrene box maintained for 1 h at $92^{\circ}C$, the temperatures inside and outside of the box were measured. Outside temperatures were lower by $5.4^{\circ}C$ in the case of film coated plates than the bare one, and inside temperatures of the former were lower by $3.6^{\circ}C$ than the latter. It can be interpreted that the PMMA composite film coated Al plates dissipate heat quicker than the bare Al plate.

• Korean Journal of Materials Research
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• v.25 no.2
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• pp.107-112
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• 2015

The oxide films formed on etched aluminum foils play an important role as dielectric layers in aluminum electrolytic capacitors. $Y_2O_3$-doped $ZrO_2$ (YZ) films were coated on the etched aluminum foils by sol-gel dip coating, and the electrical properties of YZ-coated Al foils were characterized. YZ films annealed at $450^{\circ}C$ were crystallized into a cubic phase, and as the $Y_2O_3$ doping content increased, the unit cell of $ZrO_2$ expanded and the grain size decreased. The etch pits of Al foils were filled by YZ sol when it dried at atmospheric pressure after repeating for several times, but this step could essentially be avoided when being dried in a vacuum. YZ-coated foils indicated that the specific capacitance and dissipation factor were $2-2.5{\mu}F/cm^2$ and 2-4 at 1 kHz, respectively, and the leakage current and withstanding voltage of films approximately 200 nm thick were $5{\times}10^{-4}A$ at 21 V and 22 V, respectively. After being anodized at 500 V, the foils exhibited a specific capacitance and dissipation factor of $0.6-0.7{\mu}F/cm^2$ and 0.1-0.2, respectively, at 1 kHz, while the leakage current and withstanding voltage were $2{\times}10^{-4}-3{\times}10^{-5}A$ at 400 V and 420-450 V, respectively. This suggests that YZ film is a promising dielectric that can be used in high voltage Al electrolytic capacitors.

• Journal of the Korean Ceramic Society
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• v.38 no.5
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• pp.401-404
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• 2001

Barium ferrite powders were synthesized by the coprecipitation method using iron-pickling waste acid (IPWA) and BaCl$_2$$.$2H$_2$O as raw materials. Fe$\^$2+/ ions in the IPWA, which contains both Fe$\^$2+/ and Fe$\^$3+/ ions, were oxidized into Fe$\^$3+/ ions using H$_2$O$_2$. Proper amount of BaCl$_2$$.$2H$_2$O was dissolved into the oxidized IPWA. Using NaOH, Ba$\^$2+/ and Fe$\^$3+/ ions were coprecipitated as Ba(OH)$_2$and Fe(OH)$_3$. The coprecipitated Ba(OH)$_2$and Fe(OH)$_3$were washed and dried. Barium ferrite powders were obtained by calcining the dried Ba(OH)$_2$and Fe(OH)$_3$mixture from 400$\^{C}$ to 1000$\^{C}$ with a 100$\^{C}$ interval. Barium ferrite powders were characterized by X-ray diffraction, SEM, and VSM. It was found that barium ferrite powders could be synthesized at around 630$\^{C}$. The synthesized barium ferrite powders showed hexagonal plate shapes with a fairly uniform size. The barium ferrite powder calcined at 900$\^{C}$ showed good magnetic properties, saturation magnetization of 67emu/g and maximum coercivity of 5000 Oe.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.31 no.6
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• pp.264-269
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• 2021

In this study, amorphous aluminum silicate powder was prepared using co-precipitation method, and the influence of spray-dried aluminum silicate granular powder was analyzed and optimized by controlling the amount of aluminum silicate powder and dispersant added to the slurry. As a result, granular powder was optimally produced under the conditions of powder content of aluminum silicate slurry of 27.5 wt% or less, dispersant addition amount of 0.8 wt% or more, pH 6~9. An average particle size of granular powder showed approximately 14 ㎛ at the powder contents of 20 and 22.5 wt% of the slurry, and approximately 19 ㎛ at the powder contents of 25 and 27.5 wt% of the slurry.

• 한국초전도학회:학술대회논문집
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• v.9
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• pp.329-333
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• 1999

The BSCCO 2223 Ag-sheathed tapes were prepared with spray dried precursor powders, which are of different starting condition. The J$_c$ in the short tapes varied from 24 kA/ cm$^2$ to 47 kA/ cm$^2$ at 77K and 0T. The largely improvement of J$_c$ in certain tape, which characterized with the large textured BSCCO 2223 grains, homogeneity of reactant and fewer tracks of second phases in final superconducting matrixes, could be due to optimization in the precursor powder.

• Proceedings of the Korean Society For Composite Materials Conference
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• 2005.11a
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• pp.71-74
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• 2005

In this paper, the effects of the MWCNTs on the PTC characteristics of the conventional CB/polymer nanocomposites were investigated. For the uniform dispersion of the MWCNTs in the polymer matrix., nitricacid-treated MWCNTs were dispersed with the dissolved HOPE in the solvent. After evaporating solvent, the dried master batches in the oven were melt blended mixed with CB and HDPE to obtain the PTC materials. The initial resistivity of PTC materials decreased and the PTC intensity increased with the MWCNTs. During three repeated heating and cooling cycles, the PTC materials containing MWCNTs showed a great reproducibility due to the conductive network structures of CB particles and MWCNTs.