• Korean Journal of Environmental Agriculture
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• v.21 no.2
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• pp.144-148
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• 2002

This study was carried out to investigate sewage treatment efficiencies using water hyacinth (Eichhornia crassipes) and watercress (Oenanthe Javanica). In the hyacinth system about 30% of COD introduced was removed during 2 days of hydraulic retention time, and about 30$\sim$50% of COD was removed in the watercress system during 1.2$\sim$2 days of hydraulic retention time. Therefore, COD loading of $76\sim170$ kg $COD/ha{\cdot}day$ was removed during 2$\sim$3 days of hydraulic retention time at the 0.18 $m^2$ area in the water hyacinth-watercress continuous system. Also 40$\sim$50% of N and P in the sewage were removed in the tested water hyacinth-watercress system Although COD, N and P concentrations in the final effluent were still higher than the limits of waste discharge, applicability of this waste water treatment system should be further investigated as an alternative method far small scale sewage treatments.

• Journal of Environmental Science International
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• v.19 no.3
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• pp.371-377
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• 2010

The purpose of this study is to investigate treatment efficiency in dyeing wastewater treatment by the high rate aeration system(HRA) and a combination of the HRA with magnetized wastewater treatment system(MWS). At the hydraulic retention time of 16hr, 24hr, 30hr, BOD removal efficiencies of HRA system were 93%, 96% and 98%, combination of the HRA with MWS system were 94%, 96.8% and 98.2%, respectively. In ease of COD, at the hydraulic retention time of 16hr, 24hr, 30hr, COD removal efficiencies of HRA system were 66%, 77.1% and 83.1%, combination of the HRA with MWS system were 70.2%, 80.1% and 86.6%, respectively. The comparison of the HRA and combination of the HRA with MWS, effluent BOD of the former was 22.7mg/${\ell}$ and the latter was 19.4mg/${\ell}$, theretore biological treatment efficiency identified to increase by the MWS.

• Restorative Dentistry and Endodontics
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• v.31 no.4
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• pp.300-311
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• 2006

The purpose of this study is to evaluate prospectively the effect of different bonding systems and retention grooves on the clinical performance of resin restorations in non-carious cervical lesions (NCCLs). Thirty-nine healthy adults who had at least 2 NCCLs in their premolar areas were included in this study. One hundred and fifty teeth were equally assigned to six groups: (A) Scotchbond Multi-Purpose (SBMP, 3M ESPE, St. Paul, MN, USA, 4th generation bonding system) without retention grooves; (B) SBMP with retention grooves; (C) BC Plus (Vericom Co., Anyang, Gyeonggido, Korea, 5th generation bonding system) without retention grooves; (D) BC Plus with retention grooves; (E) Adper Prompt (3M ESPE, Seefeld, Germany, 6th generation bonding system) without retention grooves; (F) Adper Prompt with retention grooves. All cavities were filled with a hybrid composite resin. Denfil (Vericom Co., Anyang, Gyeonggido, Korea) by one operator. Restorations were evaluated at baseline and at 6-month recall, according to the modified USPHS (United States Public Health Service) criteria. Additionally, clinical photographs were taken and epoxy resin replicas were made for SEM evaluation. At 6-month recall, there were some differences in the number of alpha ratings among the experimental groups. But, despite the differences in the number of alpha ratings, there was no significant difference among the 3 adhesive systems (p < 0.05). There was also no significant difference between the groups with or without mechanical retention (p < 0.05). Follow-ups for longer periods than 6 months are needed to verify the clinical performance of different bonding systems and retention grooves.

• The Korean Journal of Urological Oncology
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• 제15권3호
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• pp.178-186
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• 2017

Purpose: Poloxamer 407 (P407) thermo-sensitive hydrogel formulations were developed to enhance the retention time in the urinary bladder after intravesical instillation. Materials and Methods: P407 hydrogels (P407Gels) containing 0.2 w/w% fluorescein isothiocyanate dextran (FD, MW 4 kDa) as a fluorescent probe were prepared by the cold method with different concentrations of the polymer (20, 25, and 30 w/w%). The gel-forming capacities were characterized in terms of gelation temperature (G-Temp), gelation time (G-Time), and gel duration (G-Dur). Homogenous dispersion of the probe throughout the hydrogel was observed by using fluorescence microscopy. The in vitro bladder simulation model was established to evaluate the retention and drug release properties. P407Gels in the solution state were administered to nude mice via urinary instillation, and the in vivo retention behavior of P407Gels was visualized by using an in vivo imaging system (IVIS). Results: P407Gels showed a thermo-reversible phase transition at $4^{\circ}C$ (refrigerated; sol) and $37^{\circ}C$ (body temperature; gel). The G-Temp, G-Time, and G-Dur of FD-free P407Gels were approximately $10^{\circ}C-20^{\circ}C$, 12-30 seconds, and 12-35 hours, respectively, and were not altered by the addition of FD. Fluorescence imaging showed that FD was spread homogenously in the gelled P407 solution. In a bladder simulation model, even after repeated periodic filling-emptying cycles, the hydrogel formulation displayed excellent retention with continuous release of the probe over 8 hours. The FD release from P407Gels and the erosion of the gel, both of which followed zero-order kinetics, had a linear relationship ($r^2=0.988$). IVIS demonstrated that the intravesical retention time of P407Gels was over 4 hours, which was longer than that of the FD solution (<1 hour), even though periodic urination occurred in the mice. Conclusions: FD release from P407Gels was erosion-controlled. P407Gels represent a promising system to enhance intravesical retention with extended drug delivery.

• Textile Coloration and Finishing
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• v.21 no.2
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• pp.7-13
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• 2009

The effects of 0.1g/dl nonionic surfactant solutions on liquid wetting and retention properties of wool fabric are reported. The 10 different nonionic surfactants (Span 20, Tween 20, 40, 60, 80, 21, 61, 81, 65, 85), wool cloth (EMPA 217), and wool soiled cloth (EMPA 107) are used in the study. Both EMPA 217 and 107 have water contact angle($\Theta$)>$90^{\circ}$, which indicates that water spreading over a fabric surface and penetration into the fabric rarely occur. However, EMPA 217 and 107 are easily wetted with perchloroethylene(PCE) having very low values of $\Theta$'s and high values of liquid retention. Water wetting properties are greatly improved by adding nonionic surfactants into the system. Generally, hydrophilic surfactants which have low number of carbon atoms or unsaturated hydrophobic structures are effective in improving water wetting of wool fabrics. The water retention of EMPA 217 and 107 in surfactant solutions have positive relations with $cos{\Theta}$, adhesion tension, and work of adhesion. 40.3% pore volume of EMPA 217 and 26.1% pore volume of EMPA 217 can be filled with water even when we assume $cos{\Theta}=1$ (${\Theta}=0^{\circ}$).

• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.32 no.3
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• pp.18-24
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• 2000

To evaluate the efficiency of various cationic starches in improving retention drainage and strength properties of newsprints which are being made using extensive amount of domestic recycled wastepapers in a highly closed papermaking system diverse cationic starches have been prepared and tested. In the case of cationic starches with low charge density as the degree of substitution increas-es fines retention increased. Results also showed that the retention efficiency decreased sub-stantially for cationic starches with low DS when the conductivity of white water inceased. Tensile strength increased with the addition of cationic starches and then decreased. On the other hand internal bonding strength increased linearly with the addition of cationic starch. Oxidizing treatment of cationic starch was detrimental for retention and freeness improve-ment. Also crosslinking treatment of wet processed cationic starches made cationic starches less effective in retention and drainage.

• Journal of the Korean Society of Clothing and Textiles
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• v.27 no.9_10
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• pp.1153-1159
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• 2003

The effects of changing aqueous solution properties by nonionic surfactants on wetting behavior and water retention properies of hydrophobic PET (polyethylene terephthalate) fabric were reported. The aqueous solution properties were diversified by mixing and diluting two nonionic surfactants, i.e., sorbitan monolaurate (Span 20) and polyoxyethylene(20) sorbitan monolaurate (Tween 20). The surface wetting properties ($cos{\theta}$) of PET fabric were greatly improved by adding $10^{-1}g/dl$ Tween 20 and further improved by mixing Span 20 to the system. The water retention properties (W) of PET fabric were also greatly increased by addition of $10^{-1}g/dl$ Tween 20. In diluted surfactant systems, the $cos{\theta}'s$ were increased with decreasing surface tension of aqueous liquids. The ratios of aqueous liquid retained in the pore structure to liquid retention capacity (W/H) were also increased with decreasing surface tension, however, W/H values were dramatically increased right after critical micelle concentration (cmc). The existence of micelles was important for the retention of aqueous liquids in the fabric. The critical surface tension of PET fabric used was found to be 28.7dyne/cm.

• Journal of Environmental Health Sciences
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• v.27 no.3
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• pp.11-20
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• 2001

An anaerobic sludge-aerobic fixed-bed biofilm(packed with ceramic support carrier of 1 inch size) reactor system was built up to treat textile wastewater. The efficiency of reactor system was examined by determining the effects of textile wastewater ratio(from 25% to 100% at HRT 24 h). The influent range of SCOD concentration and color were 1,036~1,357 mg/L, and 1,487~1,853 degree, respectively. When textile wastewater ratio was 100% and hydraulic retention time was 24 hours, SCOD removal efficiency by the anaerobic stage were 39.2% 100% and hydraulic retention time was 24 hours, SCOD removal efficiency by the anaerobic stage were 39.2% and the removal efficiency of the whole system were 75.8%. Color removal efficiency by the anaerobic stage were 45.4%(soluble color), and the removal efficiency of the whole system were 70.2%. In the A/A reactor system, the aerobic stage played an important role in removing both color and COD as well as anaerobic stage.

• Proceedings of the Korea Technical Association of the Pulp and Paper Industry Conference
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• 2009.04a
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• pp.23-28
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• 2009

The purpose of this study was to improve not only wet-end performances but also paper characteristics by the modification of various factors like molecular design and ionic characteristics of polyacrylamides First of all physical characteristics were observed after modify molecular design of the cationic polyacrylamides to linear, branched and cross-linked. In addition it was found analysis method to confirm branch degree of cationic polyacrylamides to combine ionic titration characteristics and spectroscopic behavior, After application of these structure modified polyacrylamides to the multiple retention systems with inorganic microparticles, it was found adjusting of branch degree of polyacrylamides was very important to optimize wet-end improvement. Second, After polymerization of amphoteric polyacrylamide to have both of cationic and anionic functional group in the polymer, we observed not only physical characteristics but also wet-end improvement to apply recycled pulp and found that the improvement of solution stability to prevent hydrolysis and increase of ash retention dramatically to compare traditional cationic polyacrylamide retention aid, Finally, After polymerization of anionic polyacrylamide, we observed not only wet-end improvement but also paper characteristics to apply preflocculation of PCC and it was found the improvements of flocculation efficiency, retention, ash retention, optical properties of the paper and bursting strength to compare traditional preflocculant of cationic polyacrylamide.

• Proceedings of the Korean Geotechical Society Conference
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• 2005.03a
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• pp.1461-1467
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• 2005

In this study, a new earth retention system has been developed and introduced. This system is a self-supported earth retaining wall without struts. The new earth retention system consists of connected double H-pile and wale. This system provides a larger spacing of support, economical benefit, construction easiness, good performance and safety. This paper explains basic principles and mechanism of self-supported earth retaining wall. In order to investigate applicability and safety of this system, numerical analysis was performed. The finite differential method program, FLAC3D is used. The predicted performances of this system were presented and discussed.