• Journal of Korean Society of Water and Wastewater
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• v.22 no.1
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• pp.87-92
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• 2008

Purposes of this study were to evaluate operational performance of submerged membrane bioreactor (MBR) combined with periodic chemical backwash. Five lab-scale submerged MBRs were performed in accordance with NaOH dose, backwash solution volume. While filtration resistance of MBR system without backwash (Control) was increased persistently from startup, those of four MBR systems (RUN 1-4) with chemical backwash were maintained at $(1.4{\pm}0.16){\times}10^{12}$, $(8.6{\pm}0.90){\times}10^{11}$, $(1.9{\pm}0.10){\times}10^{12}$, $(1.4{\pm}0.10){\times}10^{12}l/m$, respectively. Under chemical backwash condition of 0.0230 M, 375 mL, permeability of membrane was highest at flux of $30L/m^2/hr$. According to results from experiment that changing condition of dose and volume, it was estimated that effect of chemical dose acts more greatly than backwash solution volume. Because COD removal rates of all MBR systems with chemical backwash were more than 96%, it was proved that NaOH added to backwash solution did not affect microorganism.

• Textile Coloration and Finishing
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• v.3 no.1
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• pp.1-7
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• 1991

The influences, that various mercerization conditions had on the dying property of cotton fiber, were studied. Crystallization degrees accompained by lattice transformation of slack-mercerized cotton by IR spectroscopic analysis and morphology of the slack-merceized cotton by SEM were observed in this research. The above results were as follows; 1. Equilibrium dye adsorption rates of slack-mercerized cotton with C. I. Reactive Blue 19 were gained in the case of 8M NaOH, $10^{\circ}C$, 20 min., about 2 times as large as the rates of untreated cotton and gained about 2.5 times in the case of 8M $NH_3$, $10^{\circ}C$, , 20 min. 2. Equilibrium dye adsorption rates of slack-mercerized cotton with C. I. Reactive Blue 2 were gained in the case of 2M NaOH, $10^{\circ}C$, 20 min., about 1.7 times as large as the rates of untreated cotton and gained about 2.4 times in the case of 8M $NH_3$, $10^{\circ}C$, 20 min. 3. It was confirmed by SEM that untreated cotton fibrils are formed in the shape of screw and treated cotton is rearranged in the direction of fiber axis.

• Journal of the Korean Ceramic Society
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• v.17 no.3
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• pp.121-128
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• 1980

In order to obtain the fundamental data for the preparation of ferroxplana $Zn_2Y(Ba_2Zn_2Fe_{12}O_{22})$, which is useful for GHz-band communication, the optimum coprecipitation condition of $Zn(NO_3)_2-6FeCl_3$ in $NH_4OH$ solution and the formation process of the hexagonal ferrite were investigated. By the hot-petroleum-drying and calcining the coprecipitated hydroxide mixture $Zn(OH)_2 +Ba(OH)_2+ 6Fe(OH)_3$, the fine and uniform powder was obtained , whose phase composition and microstructure were studied by X.R.D. and electron microscope. In results, it was found that $Zn_2Y$, BaM and $Zn_2W$ were the representative phases in calcined specimens whose activation energies of crystal growth were about 3, 8, 2.5, $5.4{\times}10^4$ J/mole , respectively. The sintered specimens would be appreciated as useful magnetic cores for the high frequency communication.

• Journal of Korean Society on Water Environment
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• v.35 no.6
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• pp.550-556
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• 2019

This study was carried out to improve the photocatalytic reaction of TiO₂ photocatalyst. During the photocatalytic reaction, OH radicals are generated and they have an excellent oxidation capability for wastewater treatment. To evaluate the OH radicals generated according to crystallographic structure of TiO₂ nanotubes photocatalyst, a probe compound, 4-Chlorobenzoic acid was monitored to evaluate OH radical. Ultraviolet light was applied for photocatalytic reaction of TiO₂. The 4-Chlorobenzoic acid solution was prepared at laboratory. TiO₂ nanotube was grown on titanium plate by using anodization method. The annealing temperature for TiO₂ nanotube was varied from 400 to 900 ℃ and the crystal forms of the TiO₂ nanotube was analyzed. Depending on annealing temperature, TiO₂ nanotubes have shown different crystal forms; 100% anatase (0 % rutile), 18.4 % rutile (81.6 % anatase), 36.6 % rutile (63.4 % anatase) and 98.6% rutile (1.4% anatase). As the annealing temperature increases, the rutile ratio increases. OH radical generation from 18.4 % rutile TiO₂ nanotube plate was about 3.8 times higher than before annealing and 1.4 times higher than only 100 % anatase-TiO₂ nanotube. The efficiency of the 18.4% rutile TiO₂ nanotube was the best in comparison to TiO₂ nanotube with 18.4 %, 36.6 % and 98.6 % rutile. As a result, photocatalytic ability of 18.4 % rutile-TiO₂ nanotube plate was higher than 100 % anatase-TiO₂ nanotube plate.

• Journal of fish pathology
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• v.28 no.2
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• pp.113-116
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• 2015

A $0.45-{\mu}m$ membrane filter is generally used to remove bacterial contamination during virus extraction from fish samples. However, the number of fish viruses is drastically reduced after filtration with a $0.45{\mu}m$ filter. In this study, we investigated the effect of filters on virus infectivity titer and the change in virus titer and bacterial number following different centrifugation conditions to determine a suitable procedure for virus extraction from fish samples. $10^{4.05}$ and $10^{5.05}TCID_{50}/ml$ of infectious hematopoietic necrosis virus (IHNV) and $10^{4.05}$ and $10^{4.55}TCID_{50}/ml$ of Oncorhynchus masou virus (OMV) were not detectable after filtration with two types of $0.45-{\mu}m$ filters, except the IHNV titer was reduced by about 10 fold after filter use (company A). No significant difference was found in the virus titer following centrifugation at $880{\times}g$ (30 min) or $3,500{\times}g$ (30 min), whereas IHNV and OMV titers were reduced by about 10 and 10-1000 fold by centrifugation at $14,000{\times}g$ (30 min) and $14,000{\times}g$ (10 and 30 min), respectively. A total of 97.7-99.9% Escherichia coli were eliminated by centrifugation at $880 {\times}g$ (30 min) and $3,500{\times}g$ (30 min). These results show that fish viruses were affected by filtering, even though the effect differed by virus species and filter type. Therefore, centrifugation at $3,500{\times}g$ (30 min) and use of medium with antibiotics may be useful for virus extraction along with a reduction in bacteria.

• Fashion & Textile Research Journal
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• v.15 no.2
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• pp.302-308
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• 2013

This study is a preliminary investigation of the influence of surface characteristics of substrates on detergency of particulate soil. The surface of PET film was modified with NaOH and NaOH+ethylene diamine on different times. The surface morphology of the film was scanned by AFM and surface energies were calculated from measured contact angles between several solutions and film based on the geometric mean and a Lewis acid base method. The surface morphology of PET film treated with NaOH and NaOH+ethylene diamine became more etched, and the surface area, surface roughness and the coefficient of friction of film increased with treatment of NaOH and NaOH+ethylene diamine. The contact angle of film treated with NaOH and NaOH+ethylene diamine decreased in water and surfactant solution; in addition, the surface energy increased was largely attributed to the increased portion on the polar surface energy of film. However, the effect of the diamine addition to the NaOH treatment solution on surface characteristics of PET film was insignificant.

• Proceedings of the Korean Vacuum Society Conference
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• 2006.08a
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• pp.86-86
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• 2006

• Journal of the Korean Ceramic Society
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• v.38 no.4
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• pp.319-324
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• 2001

본 연구에서는 NaOH로 첨착시킨 활성탄의 표면특성변화와 H$_2$S 흡착능을 고찰하였다. 첨착시약으로 사용된 NaOH 용액의 농도는 1~8N이며, 활성탄의 입자크기는 8$\times$30mesh가 적용되었다. 실험결과는 첨착율이 0.87~5.8% 범위 내에서 증가할수록 BET 표면적은 1050$m^2$/g에서 783$m^2$/g로 감소하며, 표면산도는 0.541meq/g-AC에서 0meq/g-AC으로 감소하고, pH는 9.56에서 10.86으로 증가하는 것으로 밝혀졌다. 또한 NaOH로 첨착시킨 활성탄의 H$_2$S 평형흡착능을 보임으로써 비첨착활성탄에 비해 2~3배 높은 수준을 나타냄을 알 수 있었다.

• Korean Journal of Organic Agriculture
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• v.12 no.4
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• pp.399-409
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• 2004

This study was conducted to investigate the effect of different concentrations of microbial products on growth of chinese cabbage and microorganisms in soil. Two different levels of microbial products, such as 50 times and 100 times diluted solutions of chitosan, wood vinegar and EM activity liquid, were treated for foliar application. the results were summarized as follows : Among foliar applications of microbial products, 100 times diluted solution of chitosan was effective on growth of chinese cabbage comparing to other levels of dilutions and untreated control plot. The number of microorganism in the soil tended to increase under the treatment of microbial products compared to control plot. Especially, the numbers of the bacteria and actinomycetes were estimated $73.67{\times}10^3$ CFU/g and $34.00{\times}10^3$ CFU/g, respectively, under the treatment of 100 times diluted solution of chitosan.

• Proceedings of the Korean Information Science Society Conference
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• 2012.06c
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• pp.344-346
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• 2012

스마트폰에서의 3D 게임/애플리케이션에 대한 사용자의 요구는 나날이 증가하고 있다. 3D 게임/애플리케이션은 내부적으로 $4{\times}4$ 행렬을 가지고 여러 가지 좌표 변환을 수행하기 때문에, 보다 빠른 3D 그래픽스 처리를 위해서는 $4{\times}4$ 행렬 연산의 최적화가 필수적이다. $4{\times}4$ 행렬 연산중에 역행렬 연산에 대해 살펴보고, ARM 프로세서에서 지원하는 Neon 연산자를 이용해서 $4{\times}4$ 행렬의 역행렬 연산을 개선할 수 있다.