• Journal of Korean Society of Water and Wastewater
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• v.27 no.2
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• pp.215-222
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• 2013

The fluctuation of inlet flow to a water treatment plant makes a serious problem that it can change the outlet flowrate from each process abruptly. Since it takes very short time for the surface wave occurred from the fluctuation of inlet flow to reach the latter processes, it is impossible for operators to cope with that stably. In order to investigate the characteristics of hydraulic behavior for rectangular sedimentation basin in water treatment plant, CFD(Computational Fluid Dynamics) simulation were employed. From the results of both CFD simulations, it was confirmed that time taken for the follow-up processes by the fluctuation in intake well can be estimated by the propagation velocity of surface waves. Also, it takes very short time for the surface wave occurred from the fluctuation of inlet flow to reach the latter processes. In the case of inlet flowerate being increased sharply, local velocity within sedimentation basin appeared as wave pattern and increased due to convection current. Also, it could be observed that vortex made local velocity in the vicinity of bottom rise.

• Proceedings of the Korean Society of Agricultural Engineers Conference
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• 2001.10a
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• pp.470-474
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• 2001

A pilot study was performed at the experimental field of Konkuk University in Seoul, to examine the waste water treatment using constructed wetland and pond system. The effluent of the wetland system in winter often exceeded effluent water quality standards for sewage treatment plant, therefore, pond system could be applied to additional system. As a result, removal rate of $BOD_{5}$, SS was 84.4%, 81.5% and effluent concentration was 4.6mg/L and 5.0mg/L respectively, when surface water of pond system was discharged in March. So we concluded that pond system stored wetland effluent in winter and discharged surface water of pond system in March, so met water quality standard.

• Membrane and Water Treatment
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• v.4 no.2
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• pp.109-126
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• 2013

Surface modification by low-pressure ammonia ($NH_3$) plasma on commercial thin-film composite (TFC) membranes was investigated in this study. Surface hydrophilicity, total surface free energy, ion exchange capacity (IEC) and zeta (${\zeta}$)-potentials were determined for the TFC membranes. Qualitative and quantitative analyses of the membrane surface chemistry were conducted by attenuated total reflectance Fourier transform infrared (ATR FT-IR) spectroscopy. Results showed that the $NH_3$ plasma treatment increased the surface hydrophilicity, in particular at a plasma treatment time longer than 5 min at 50 W of plasma power. Total surface free energy was influenced by the basic polar components introduced by the $NH_3$ plasma, and isoelectric point (IEP) was shifted to higher pH region after the modification. A ten (10) min $NH_3$ plasma treatment at 90 W was found to be adequate for the TFC membrane modification, resulting in a membrane with better characteristics than the TFC membranes without the modification for water treatment. The thin-film chemistry (i.e., fully-aromatic and semi-aromatic nature in the interfacial polymerization) influenced the initial stage of plasma modification.

• Restorative Dentistry and Endodontics
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• v.13 no.1
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• pp.123-129
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• 1988

The purpose of this study was to evaluate the bond strength of glassionomer cement against cut dentin surface which was treated with various surface cleaning agents. 48 freshly extracted human 3rd molars were ground flat through the enamel into the dentin using 600 grit silicone carbide paper under a flow of water. The were divided into four groups by the following cleaning procedure on cut dentin surface; Group I : No surface treatment after grinding with 600 grit silicone carbide paper as control group Group II : Surface treatment with 50% citric acid for 30 seconds. Group III : Surface treatment with 37% phosphoric acid for 30 seconds. Group IV : Surface treatment with 10% poly acrylic acid for 30 seconds. The specimens in 4 groups were immersed in distilled water at $37^{\circ}C$ for 24 hours before testing after cleanising with water-spray and drying with air. Bond strength was measured with Instron Universal Testing Machine (Autograph S-100, Shimadzu, Kyoto, JAPAN). The results were as follows: 1. The bond strengths of group II, III & IV were not seemed to be shown more significant improvement than a group I. 2. The bond strengths in groups which were treated with 50% citric acid, 37% phosphoric acid and 10% polycrylic acid, were ranked 24.70kg/$cm^2$, 22.02kg/$cm^2$ and 31.13kg/$cm^2$, but its difference was not significant, statistically.

• Journal of Korean Society of Water and Wastewater
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• v.22 no.3
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• pp.323-328
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• 2008

During the full-scale water treatment operation at "G" Water Treatment Plant in Seoul, we investigated changes in pore volume distribution and specific surface area of GAC with time. The pore volume of the used GAC decreased to the level below 0.6 cc/g while that of the brand new GAC was ranged 0.7~0.9 cc/g. The specific surface area of GAC pores changed within the range between $1100{\sim}1200m^2/g$ and $700{\sim}800m^2/g$. Bacteria attached to the surface of GAC shows a gradual increase ($0.4{\time}10^6{\sim}8.5{\time}10^6CFU/g$) under scanninig electron microscope (SEM). TOC removal was enhanced due to growth of the attached bacteria on GAC. It was found that TOC removal was closely related with physical parameters (pore volume, specific surface area) linearly under the investigated conditions. The used GAC need to be exchanged into new one or re-generated to remove organic matters (TOC) effectively from the finished drinking water.

• Textile Coloration and Finishing
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• v.6 no.3
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• pp.27-36
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• 1994

In order to produce a water repellent surface on polyester fabric, samples were treated in the atmosphere of $CF_4$ glow discharge plasma. The samples used in the study were ployester fabric and poyester film. The purpose of film treatment is for the comparison of hydrophobicity with fabric sample at same treatment condition. Radio frequency(13.56MHz) generator was used as electric source and its in put power is 100 Watt. Water repellency was evaluated by contact angle measurement. Result obtained are as follows. 1) Fiber interstice of original fabric was ana lysed as 0.43$\mu$m, and this value was sufficiently ideal for making water repellent fabric. 2) The most favorable setting position of substrate was the center area between two electrodes. 3) Fabric contact angle was higher than film contact angle at same treatment condition, and its difference was more than 50${\circ}$. And it was incapalbe of fabric contact angle measurement when the film contact angle was less than 90${\circ}$. because the fabric is susceptible to absorption of water by the capillary effect. 4) Fabric contact angle can not revealed the precise defferences of surface hydrophobicity, however, the film contact angle showed the real hydrophobic nature. 5) It was not sufficient method to evaluate the hydrophobicity of fabric surface by merely measure of the water contact angle. 6) It showed high water repellent nature at 0.06 torr of $CF_4$ plasma gas pressure and duration of 45 seconds treatment, and it can not be anticipated more improved nature if the pressure and duration of treatment time were increased.

• Applied Chemistry for Engineering
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• v.27 no.1
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• pp.62-67
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• 2016

In this study, a pellet-type adsorbent was prepared by using the water-treatment sludge as a raw material, and its physical and chemical properties were analyzed through $N_2$-adsorption, XRD, XRF, and $NH_3$-TPD measurements. Adsorption performance for gaseous ammonia and formaldehyde was compared between the pellet-type adsorbents prepared from water-treatment sludge and the impregnated activated carbon. Although the surface area and pore volume of the pellet-type adsorbent produced from water-treatment sludge were much smaller than those of the impregnated activated carbon, the pellet-type adsorbent produced from water-treatment sludge could adsorb ammonia gas even more than that of using the impregnated activated carbon. The pellet-type adsorbent prepared from water-treatment sludge showed a superior adsorption capacity for ammonia which can be explained by chemical adsorption ascribed to the higher amount of acid sites on the pellet-type adsorbent prepared from water-treatment sludge. In the case of formaldehyde adsorption, the impregnated activated carbon was far superior to the adsorbent made from the water-treatment sludge, which can be attributed to the increased surface area of the impregnated activated carbon.

• Journal of the Korea institute for structural maintenance and inspection
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• v.18 no.1
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• pp.68-74
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• 2014

Recently, concrete facility as advanced water treatment facilities is extending in the water treatment facilities according to raise awareness of pure drinking water and delicious water. For this reason, it is increased to the necessity need to make the standard and the development of waterproofing and anti-corrosion materials for concrete structures applied water treatment tank. So, related research has become active recently. However, as the limit of research focused on durability improvement of top coating material, it is insufficient to study on the adhesion strength between the concrete surface and primer. Therefore, there is to confirm the adhesion of between concrete surface and the three primers used as anti-corrosion waterproofing materials, and to investigate the properties of adhesion strength according to the condition such as dry condition, wet condition, and water pressure condition of the concrete surface in this study.

• Textile Coloration and Finishing
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• v.18 no.1
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• pp.20-27
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• 2006

On the purpose of surface modifications of polypropylene meltblown(PPMB) nonwovens, PPMB nonwovens were treated in the plasma system by oxygen atmosphere with different treatment time and discharge power. Dimensional change and physical properties of the treated nonwovens were evaluated. Contact angles onto PPMB nonwovens about water and methyleneiodide were measured and surface energies were calculated by Owen's method. As the results, microcraters were observed on the surface of treated nonwovens. Tenacity and breaking strain of PPMB nonwovens decreased with increasing treatment time and discharge power. Surface energy of PPMB nonwovens increased by plasma treatment. Meanwhile, the friction static voltage and dyeability of PPMB nonwovens have enhanced to some extent by oxygen plasma treatment due to the improvement of surface hydrophilicity.

• Membrane and Water Treatment
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• v.9 no.4
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• pp.233-243
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• 2018

In this manuscript, $35m^3/d$ NF unit was designed and applied for surface water treatment of the River Nile water. Intake of Embaba drinking water treatment plant was selected to install that unit at since; it has the lowest water quality index value through the examined 6 sites in greater Cairo area. The optimized operating conditions were feed and permeate flow, 40 and $7m^3/d$, feed pressure 2.68 bar and flux rate $37.7l/m^2h$. The permeate water was drinkable according to Egyptian Ministerial decree 458/2007 for the tested parameters (physic-chemical, heavy metals, organic, algal, bacteriological and parasitological). Single and double sand filters were used as pretreatment for NF membranes but continuous clogging for sand filters moved us to use UF membrane as pretreatment for NF membrane.