• Membrane and Water Treatment
• /
• v.3 no.3
• /
• pp.151-168
• /
• 2012

Gas sparging is one of the techniques used to control the concentration polarization during ultrafiltration. In this work, the effects of gas sparging in stratified flow regime were investigated during gel layer controlling cross flow ultrafiltration in a rectangular channel. Synthetic solution of pectin was used as the gel forming solute. The liquid and gas flow rates were selected such that a stratified flow regime was prevalent in the channel. A mass transfer model was developed for this system to quantify the effects of gas flow rates on mass transfer coefficient (Sherwood number). The results were compared with the case of no gas sparging. Gas sparging led to an increase of mass transfer coefficient by about 23% in this case. The limitation of the developed model was also evaluated and it was observed that beyond a gas flow rate of 20 l/h, the model was unable to explain the experimental observation, i.e., the decrease in permeate flux with flow rate.

• Journal of Sensor Science and Technology
• /
• v.19 no.3
• /
• pp.202-208
• /
• 2010

This study examined the dependency of crystalline orientation and electric properties of sol-gel PZT film on hydrolysis, a $PbTiO_3$ seed layer and a concentration of sol-gel solution. The PZT thin films were prepared by using 2-Methoxyethanol-based sol-gel method and spin-coating on Pt/Ti/$SiO_2$/Si substrates. The 1-${\mu}m$-thick PZT films were coated and then fired in a furnace by direct insert method. The highly (111) oriented PZT film of pure perovskite structure could be obtained. We could control the degree of orientation by various parameters such as hydrolysis, a $PbTiO_3$ seed layer and a concentration of sol-gel solution. The highest measured remanent polarization, dielectric constant and piezoelectric coefficient are $24.16\;{\mu}C/cm^2$, 2808, and 159 pC/N, respectively.

• Proceedings of the Materials Research Society of Korea Conference
• /
• 2007.11a
• /
• pp.156.2-156.2
• /
• 2007

• Proceedings of the Korean Ceranic Society Conference
• /
• 2000.10a
• /
• pp.197.2-197
• /
• 2000

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2001.07a
• /
• pp.1039-1042
• /
• 2001

A method for designing antireflection (AR) and antistatic (AS) films by the use of conducting polymer as an electrically conductive transparent layer is proposed. The conducting AR film is composed of four-layer with alternating high and low refractive index layer: silicon dioxide (n=1.44) and titanium dioxide (n=2.02) prepared at low temperature by sol-gel method are used as the low and high refractive index layer, respectively. The 3,4-polyethylenedioxythiophene (PEDOT) which has the sheet resistance of 10$^4$$\Omega$/$\square$ is used as a conductive layer. Optical constant of ARAS film was measured by the spectroscopic ellipsometer and from the measured optical constants the spectral properties such as reflectance and transmittance were simulated in the visible region. The reflectance of ARAS films on glass substrate was below 0.8 %R and the transmittance was higher than 95 % in the visible wavelength (400-700 nm). The measured AR spectral properties was very similar to its simulated results.

• Journal of the Korean Society of Food Science and Nutrition
• /
• v.22 no.4
• /
• pp.476-483
• /
• 1993

The moisture sorption characteristics of commercially produced seasoned dried layer (Porphyra yezoensis) was investigated by measuring sorption isotherms. The laver and two kinds of desiccant (silica gel and zeolite based desiccant) were used at temperatures of 30, 40 and 5$0^{\circ}C$ respectively using the method of saturated salt solution. Time to reach the equilibrium moisture content at each temperature and relative humidity varied from 4~6hr for the laver to 20~25hr for the silica gel and 43~46hr for the zeolite. The isotherms of the layer and the desiccants showed the characteristic sigmoidal curve. Monomolecular layer moisture content calculated using the BET equation at each temperature (30, 40, 5$0^{\circ}C$) were 5.26, 4.46 and 3.49% (d.b.) for the laver, 17.32, 15.24 and 12.89% (d.b.) for the silica gel, 16.89, 14.92 and 14.44% (d.b.) for the zeolite, respectively, Both desiccants showed higher values of the monomolecular layer moisture content than the laver. In all cases, the monomolerular layer moisture contents were decreased linearly as the temperature was increased in the experimental ranges. Water vapor transmission rate of the packaged material was also influenced by the temperature, which could be explained by the Arrhenius equation.

• Journal of Periodontal and Implant Science
• /
• v.40 no.6
• /
• pp.257-264
• /
• 2010

Purpose: Connective tissue reattachment to periodontally damaged root surfaces is one of the most important goals of periodontal therapy. The aim of this study was to develop a root conditioning agent that can demineralize and detoxify the infected root surface. Methods: Dentin slices obtained from human teeth were treated with a novel root planing agent for 2 minutes and then washed with phosphate-buffered saline. Smear layer removal and type I collagen exposure were observed by scanning electron microscopy (SEM) and type I collagen immunostaining, respectively. Cell attachment and lipopolysaccharides (LPS) removal demonstrated the efficiency of the root conditioning agent. Results: SEM revealed that the smear layer was entirely removed and the dentinal tubules were opened by the experimental gel. Type I collagen was exposed on the surfaces of the dentin slices treated by the experimental gel, which were compared with dentin treated with other root planing agents. Dentin slices treated with the experimental gel showed the highest number of attached fibroblasts and flattened cell morphology. The agar diffusion assay demonstrated that the experimental gel also has effective antimicrobial activity. Escherichia coli LPS were effectively removed from well plates by the experimental gel. Conclusions: These results demonstrated that this experimental gel is a useful tool for root conditioning of infected root surfaces and can also be applied for detoxification of ailing implant surface threads.

• Proceedings of the KIEE Conference
• /
• 2011.07a
• /
• pp.1485-1486
• /
• 2011

A layer of $TiO_2$ thin film less than ~500nm in thickness, as a blocking layer, was coated by sol-gel method directly onto the anode electrode to be isolated from the electrolyte in dye-sensitized solar cells (DSCs). This is to prevent the electrons from back-transferring from the electrode to the electrolyte (I-/I3-). The effects of heat treatment conditions of the gel and as-coated film on the thickness and consolidation to substrate were studied. The flexible DSCs were fabricated with working electrode of Ti thin foil coated with blocking $TiO_2$ layer, dye-attached mesoporous $TiO_2$ film, gel electrolyte and counter electrode of Pt-deposited indium doped tin oxide/polyethylene naphthalate (ITO/PEN). The photo-current conversion efficiency of the cell was 5.3% ($V_{oc}=0.678V$, $J_{sc}=12.181mA/cm^2$, ff=0.634) under AM1.5, 100 mW/$cm^2$ illumination.

• Journal of Pharmaceutical Investigation
• /
• v.29 no.2
• /
• pp.127-136
• /
• 1999

In order to eliminate demerits of conventional dosage forms, dipotassium glycyrrhizate was formulated as a slim mucoadhesive film type dosage form. The mucoadhesive drug layer gel containing dipotassium glycyrrhizate was prepared using $Noveon^{\circledR}$ AA-1, hydroxypropylcellulose-M, ethylcellulose N 100 and citric acid, and the protective layer gel by using ethylcellulose N 100, $Eudragit^{\circledR}$ RS and castor oil. The viscosity of drug layer gel of mucoadhesive film was enhanced as the increased amount of $Noveon^{\circledR}$ AA-1 or hydroxypropyl cellulose-M. The drug content was unifonnly $1160{\pm}14.6\;{\mu}g$, and was varied within 3.5%. The optimum film dosage form showed a good fluidity and malleability of drug layer, with 179 g of thickness, pH 5.7, 411 min of in vitro adhesion time and 172 g in gravity adhesive strength. The release time of drug from the mucoadhesive film was significantly shorter but was delayed when polymers such as ethylcellulose was added. From these results, the new mucoadhesive film may be effective for the treatment of aphthous stomatitis.

• The Korean Journal of Ceramics
• /
• v.5 no.4
• /
• pp.353-356
• /
• 1999

Highly proten-conductive elastic composites have been successfully prepared from $H_3PO_4$-doped silica gel and styrene-ethylene-butylene-styrene block elastic copolymer. In addition solid state electric double-layer capacitors have been fabricated using the composite as an electrolyte and activated carbon powders(ACP) hybridized with the composite as a polrizable electrode. The cyclic voltammogram of the electric double-layer capacitor fabricated demonstrated that electric charge was stored in the elecric double-layer at the interface between the polarizable electrode and the electrolyte. The value of capacitance of the capacitor was 10 F/(gram of total ACP), which was comparable to that of the capacitors using conventional liquid electrolytes.