• Korean Membrane Journal
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• v.6 no.1
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• pp.10-15
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• 2004

We developed a water-selective ceramic composite membrane for use as a dehydration membrane reactor for dimethylether (DME) synthesis from methanol. The membranes were modified on the porous stainless steel support by the sol-gel method accompanied by a suction process. The improved membrane modification process was effective in increasing the vapour permselectivity by removal of defects and pinholes. The optimized alumina/silica composite membrane exhibited a water permeance of 1.14${\times}$10$^{-7}$ mol/$m^2$.sec.Pa and a water/methanol selectivity of 8.4 at permeation temperature of 25$0^{\circ}C$. The catalytic reaction for DME synthesis from methanol using the membrane was performed at 23$0^{\circ}C$, and the reaction conversion was compared with that of the conventional fixed-bed reactor. The reaction conversion of the membrane reactor was much higher than that of the conventional fixed-bed reactor. The reaction conversion of the membrane reactor and the conventional fixed-bed reactor was 82.5 and 68.0%, respectively. This improvement of reaction efficiency can last if the water vapour produced in the reaction zone is removed continuously.

• Food Science and Preservation
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• v.11 no.2
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• pp.246-249
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• 2004

This study was conducted to evaluate the inhibition efficacy of high CO$_2$ atmosphere (35, 60, and 100% ${\times}$ 24, 48, and 72 h) on growth of Botrytis cinerea in vitro in order to offer sterilizing method of horticultural crops including peach fruits. Botrytis cinerea was isolated from a naturally infected peach fruits. Growth of the fungus at 25$^{\circ}C$ declined with increased CO$_2$ concentration and treatment duration. Especially, 100% CO$_2$ provided completely inhibition effect of growth of the fungus for 72 h. After removal of high CO$_2$ condition, however, the fungus showed normal growth speed. The growth of fungus at low temperature was completely inhibited temporarily by short-term 100% CO$_2$ treatment, but resumed right after transferring to normal atmosphere at 25$^{\circ}C$.

• 한국태양에너지학회:학술대회논문집
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• 2011.11a
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• pp.245-248
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• 2011

Many researches have been carried out to improve light absorption in the crystalline silicon solar cell fabrication. The rear reflection is applied to increase the path length of light, resulting in the light absorption enhancement and thus the efficiency improvement mainly due to increase in short circuit current. In this paper, we manufactured the silicon solar cell using the mono crystalline silicon wafers with $156{\times}156mm^2$, 0.5~3.0 ${\Omega}{\cdot}cm$ of resistivity and p-type. After saw damage removal, the dielectric film ($SiN_x$)on the back surface was deposited, followed by surface texturing in the KOH solution. It resulted in single-side texturing wafer. Then the dielectric film was removed in the HF solution. The silicon wafers were doped with phosphorus by $POCl_3$ with the sheet resistance 50 ${\Omega}/{\Box}$ and then the silicon nitride was deposited on the front surface by the PECVD with 80nm thickness. The electrodes were formed by screen-printing with Ag and Al paste for front and back surface, respectively. The reflectance and transmittance for the single-sided and double-sided textured wafers were compared. The double-sided textured wafer showed higher reflectance and lower transmittance at the long wavelength region, compared to single-sided. The completed crystalline silicon solar cells with different back surface texture showed the conversion efficiency of 17.4% for the single sided and 17.3% for the double sided. The efficiency improvement with single-sided textured solar cell resulted from reflectance increase on back surface and light absorption enhancement.

• Journal of Korean Society on Water Environment
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• v.31 no.2
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• pp.87-93
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• 2015

In this study, the inhibitory effect of toxic metals was investigated on the activated sludge of the municipal sewage treatment plant. The allowable concentration of toxic metals was also estimated for the stable operation of the biological treatment process. The single and mixture toxicity of $Cu^{2+}$, $Al^{3+}$ and $Zn^{2+}$ were evaluated for the activated sludge microorganisms. As a result, nitrifying microorganisms were more susceptible than heterotrophic microorganisms. $IC_{10}$ (Inhibition Concentration of 10%) of $Cu^{2+}$, $Al^{3+}$ and $Zn^{2+}$ for the nitrifying microorganisms was 3 mg/L, 7 mg/L and 25 mg/L, respectively. The mixture toxicity showed three times more sensitive than the single toxicity. The concentrations of $Cu^{2+}$, $Al^{3+}$ and $Zn^{2+}$ to minimize the inhibitory effect on organic matter removal and nitrification in batch experiments were found to be 1.3 mg/L, 2.5 mg/L and 6.3 mg/L.

• Journal of Korean Society of Water and Wastewater
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• v.27 no.3
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• pp.299-312
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• 2013

This study investigated the contaminant loading and characteristics of particle size distributions(PSDs) in the rainfall runoff from two different sources, the pavement road and the ancillary parking lot, and then evaluated four different types of filter media(i.e., EPP, EPS, Zeolite, and Perlite) to treat runoff water. The results showed that runoff from the pavement road contains 5.6 and 20 times higher SS and Pb concentrations, respectively, than that from the parking lot. The particles smaller than $100{\mu}m$ occupied 89.8 % of runoff from the pavement road and 81.4 % of that from the parking lot by volume. The effect of the hydraulic loading, at 950 m/day filtering linar velocity and 40 cm head loss, was largest for Zeolite, followed by Perlite, EPS, and EPP. The return period of tested media calculated by the regression equation for head loss indicated that EPP has the longest life time. The average SS removal rate was similar for all media at between 84.9 % and 89 %, while the effect of various filter column heights was different, showing minimal for EPP and maximum for EPS. All filter media tested demonstrated over 95 % of SS treatment efficiency for the particles bigger than $100{\mu}m$, while for the ones smaller than $100{\mu}m$ the efficiency was in order of EPP(82.4%) > Perlite(76.1 %) > EPS(66.2 %) > Zeolite(65.2 %). The results in conclusion implies that EPP is most effective filter media for the highly contaminated fine particles from road runoff.

• Journal of Powder Materials
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• v.25 no.4
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• pp.316-321
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• 2018

Composites of P25 $TiO_2$ and hexagonal $WO_3$ nanorods are synthesized through ball-milling in order to study photocatalytic properties. Various composites of $TiO_2/WO_3$ are prepared by controlling the weight percentages (wt%) of $WO_3$, in the range of 1-30 wt%, and milling time to investigate the effects of the composition ratio on the photocatalytic properties. Scanning electron microscopy, x-ray diffraction, and transmission electron microscopy are performed to characterize the structure, shape and size of the synthesized composites of $TiO_2/WO_3$. Methylene blue is used as a test dye to analyze the photocatalytic properties of the synthesized composite material. The photocatalytic activity shows that the decomposition efficiency of the dye due to the photocatalytic effect is the highest in the $TiO_2/WO_3$ (3 wt%) composite, and the catalytic efficiency decreases sharply when the amount of $WO_3$ is further increased. As the amount of $WO_3$ added increases, dye-removal by adsorption occurs during centrifugation, instead of the decomposition of dyes by photocatalysts. Finally, $TiO_2/WO_3$ (3 wt%) composites are synthesized with various milling times. Experimental results show that the milling time has the best catalytic efficiency at 30 min, after which it gradually decreases. There is no significant change after 1 hour.

• Journal of Pharmaceutical Investigation
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• v.25 no.4
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• pp.353-363
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• 1995

The purpose of this study was to investigate the intestinal and nasal absorption enhancement of cefotaxime (CTX) by ion-pairing with counterions and to design an effective oral and intranasal drug delivery system for antibiotics. Counterions for absorption promotion were cationic surfactants [cetylpyridinium chloride (CP), cetrimide (CT) and benzalkonium chloride (BA)]. In the presence of counterions, the apparent partition coefficient of cefotaxime was increased depending on the molar concentration of the counterions. Anion interference was observed for ion-pairing of cefotaxime with counterions because of the counterbalance between an anion and counterions. The present study employed the in situ simultaneous nasal and intestinal perfusion technique in rats. The apparent permeabilities $(P_{app})$ of cefotaxime were $1.43{\pm}0.04{\times}10^{-5}\;cm/sec(mean{\pm}S.E)$ in the nasal cavity and 0 in the jejunum, respectively, which indicated that the intrinsic absorptivity of cefotaxime was greater in the nasal cavity than in the jejunum. When ionupairing formers were used, the decreasing order of apparent cefotaxime permeability $(P_{app},\;10^{-5}\;cm/sec)$, corrected for surface area of absorption, was as followings: $BA\;(7.50{\pm}0.36)\;>\;CT\;(4.92{\pm}0.24)\;>\;CP\;(3.01{\pm}0.17)$ in the jejunum and $BA\;(22.31{\pm}1.36)\;>\;CP\;(18.24{\pm}0.81)\;>\;CT \;(16.22{\pm}1.87)$ in the nasal cavity. The increase in permeability of cefotaxime was about 13-fold in the rat nasal cavity and was marked in the rat jejunum for ion-pairing with counterions as compared to those without ion-pairing. The damages of jejunal and nasal mucosal membrane by counterions were observed within approximately 2hrs after removal of ion-pair of cefotaxime with counterions from the nasal cavity and jejunum. These results suggest that CP can be used as an ion-pairing former in the jejunum and CP and CT can be used as ion-pairing formers in the nasal cavity for cefotaxime, as well as for poorly absorbed drugs with a negative charge due to ionization.

• Journal of Korean Society of Environmental Engineers
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• v.34 no.6
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• pp.391-396
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• 2012

The destruction study of $NF_3$ gas emitted from the semiconductor industry is performed with electron-beam technology. Absorbed dose (kGy) and current ranged from 0 (0) to 400 kGy (20 mA). The concentration of $NF_3$ gas ranged from 500 to 2,000 ppm. In order to assess the effect of a residence time on DRE (Destruction and Removal Efficiency, %), experiments also conducted at different irridiation times of 5 sec, 10 sec, 15 sec and 20 sec respectively. As absorbed dose and current increased, DRE of $NF_3$ was also increased. However, DRE (%) of $NF_3$ decreased with increasing the concentration of $NF_3$ gas. The DRE of $NF_3$ was about 90% at an absorbed dose of 400 kGy.

• Tuberculosis and Respiratory Diseases
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• v.45 no.4
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• pp.882-887
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• 1998

In healthy adults, diagnosis of aspiration of foreign body into tracheobronchial tree is not difficult because various symptoms such as dyspnea, coughing, or cyanosis develop when foreign body is aspirated into tracheobronchial tree. But unless a clear history of an aspiration event can be obtained, diagnosis will be delayed. Early complications of tracheobronchial foreign body aspiration include asphyxia, cardiac arrest, dyspnea, laryngeal edema, and cyanosis. Late complications include pneumonia, lung abscess, bronchiectasis, hemoptysis, bronchial stenosis, and polyp. Treatment is removal of foreign body by operation or bronchoscopy. Currently, flexible bronchoscopy is preferred in adults than rigid bronchoscopy. A 36-year-old male visited to Dongkang hospital due to productive coughing and dyspnea. On auscultation, focal inspiratory wheezing was heard. On chest PA, mild emphysematous change was seen Flexible bronchoscopy was done. Bronchoscopically, mucoid impaction, surrounding inflammation, foreign body lodged in the right lower lobe bronchus, and interbronchial fistula(between right middle and lower lobe bronchus) were seen Foreign body($2.4\{times}1.3cm$ sized antacid package) was removed by flexible bronchoscopy. Later, history of aspiration of a piece of antacid package was found. We report a case of recurrent bronchitis with interbronchial fistula as a result of occult aspiration of foreign body with review of the literatures.

• Proceedings of the KSME Conference
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• 2004.04a
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• pp.1672-1677
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• 2004

Leading edge extension(LEX) in a highly swept shape applied to a delta wing features the modem air-fighters. The LEX vortices generated upon the upper surface of the wing at high angle of attack enhance the lift force of the delta wing by way of increased negative suction pressure over the surfaces. The present 3-D stereo PIV includes the Identification of 2-D cross-correlation equation, stereo matching of 2-D velocity vectors of two cameras, accurate calculation of 3-D velocity vectors by homogeneous coordinate system, removal of error vectors by a statistical method followed by a continuity equation criterion and so on. A delta wing model with or without LEX was immersed in a circulating water channel. Two high-resolution, high-speed digital cameras($1280pixel{\times}1024pixel$) were used to allow the time-resolved animation work. The present dynamic stereo PIV represents the complicated vortex behavior, especially, in terms of time-dependent characteristics of the vortices at given measuring sections. Quantities such as three velocity vector components, vorticity and other flow information can be easily visualized via the 3D time-resolved post-processing to make the easy understanding of the LEX effect or vortex emerging and collapse which are important phenomena occurring in the field of delta wing aerodynamics.