• Membrane and Water Treatment
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• v.10 no.2
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• pp.179-189
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• 2019

This study aimed to investigate the effect of temperature and solid retention time (SRT) on membrane fouling in a membrane bioreactors (MBRs). For this purpose, a lab-scale submerged MBR system was used. This system operated at two SRTs of 15 and 5 days, three various temperatures (20, 25 and $30^{\circ}C$) and hydraulic retention time (HRT) of 8 h. The results indicated that decreased the cake layer resistance and increased particles size of foulant due to increasing temperature and SRT. Fourier transform infrared (FTIR) analysis show that the cake layer formed on the membrane surface, contained high levels of proteins and especially polysaccharides in extracellular polymeric substances (EPS) but absorbance intensity of EPS functional groups decreased with temperature and SRT. EEM analysis showed that the peak on the range of Ex/Em=220-240/350-400 in SRT of 15 and temperature of $30^{\circ}C$ indicates the presence of fulvic acid in the cake. In addition, as the temperature rise from 20 to $30^{\circ}C$, concentration of soluble microbial products (SMP) increased and COD removal reached 89%. Furthermore, the rate of membrane fouling was found to increase with decreasing temperature and SRT.

• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.31 no.5
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• pp.24-30
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• 1999

Crosslinked corn starches were prepared to increase their molecular weights and their performance as a component of Compozil system was evaluated and compared with that of potato starches. It was shown that greater improvements in retention and strength properties could be achieved when crosslinded cationic corn starches rather than conventional cationic potato starches were used especially at high conductivity because of their molecular rigidity.

• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.32 no.1
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• pp.26-32
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• 2000

The impact of major surface chemical properties of silica sols on the retention and drainage performance of the silica based micrparticle system, Compozil was investigated using four different silica sols. And the effect of silica properties on the interactions with cationic starch and cationic plyacrylamide has also been identified. The surface charge density and the stability over pH of silica sols were increased by introducing aluminosilicate anions at surface. It was found that the charge density of silica sols determined the addition level necessary to attain the maximum retention and drainage. When silica sols were combined with cationic starch, the change density of the product was the critical properties and the degree of microagregation was of minor importance. In the cationic polyacrylamide system the degree of colloid structure appeared to be a more critcial property than the charge density of silica sols.

• Journal of the Ergonomics Society of Korea
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• v.9 no.1
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• pp.15-20
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• 1990

In order to design man-machine system, communication system and other tasks that require information, we need to understand the characteristics of hyman short-term memory (STM). Thus, the purpose of this thesis is to investigate the influences of information stress and retention time on human performances and their relation- ships for STM of visual invormation. Eight subjects performed the computer monitering with STM task. The results showed that performance on serial recall from STM get wores and response time (and completion time) on information transmission by recall from STM increase as information stress and retention time increase. Also, there existed inverse proportional relationship between recall performance and response time (and completion time).

• Bulletin of the Korean Chemical Society
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• v.21 no.1
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• pp.105-109
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• 2000

High-performance liquid chromatography is suitable for getting thermodynamic information about solute-solvent interactions. We used a squalane impregnated $C_{18}$ phase as a presumably bulk-like stationary phase to secure a simple partition mechanism for solute retention in reversed phase liquid chromatographic system. We measured retention data of some selected solutes (benzene, toluene, ethylbenzene, propylbenzene, butylbenzene, phenol, benzylalcohol, phenethylalcohol, benzylacetone, acetophenone, benzonitrile, benzylcyanide) at 25, 30, 35, 40, 45, and 50 $^{\circ}C$ in 30/70, 40/60, 50/50, 60/40 and 70/30 (v/v%) acetonitrile/water eluents. The van't Hoff plots were nicely linear, thus we calculated dependable thermodynamic values such as enthalpies and entropies of solute transfer from the mobile phase to the stationary phase based on more than four retention measurements on different days (or weeks). We found that the cavity formation effect was the major factor in solute distribution between the mobile and stationary phases in the system studied here. Our data were com-pared with some relevant literature data.

• Membrane and Water Treatment
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• v.9 no.5
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• pp.343-351
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• 2018

As membrane fouling is based on various factors, it is a complex phenomenon that is hard to estimate. This study investigated membrane fouling in a thermophilic jet loop membrane bioreactor (JLMBR). With this purpose, four different empirical membrane fouling models with different sludge retention times were applied on the flow data obtained in the system. As a result of the model implementation, it was found for all sludge retention times that, standard blocking is effective in the first 1.5 hours of filtration, while cake filtration was dominant in the remaining duration. Additionally, it was observed that as the sludge retention time increases, membrane fouling rate decreases.

• International Journal of Human Ecology
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• v.8 no.2
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• pp.99-106
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• 2007

In this study, the mechanical properties related to the fabric appearance of well being functional bamboo knitted fabric before and after loess dyeing were evaluated. The mechanical properties of fabrics were measured by KES-F system, that is, shape retention, draping, wrinkle recovery, compression property, and surface properties, and total hand value of three types of knitted fabric, 100% bamboo, 100% cotton, and bamboo / cotton blend (60 / 40) were evaluated before and after loess dyeing. As a result, it was found that appearance density, shape retention, and drape coefficient of cotton knitted fabric were greater than those of bamboo knitted fabric. After loess dyeing, shape retention and drape coefficient, wrinkle recovery of bamboo knitted fabric improved and WC/C and MMD/SMD decreased. According to THV, the hand of bamboo/cotton blend knit is the best among three samples by compensation the weak properties of the two fiber. Therefore, loess dyeing seemed to be a good method for improving shape retention and hand value of 100% bamboo and bamboo blended fabric.

• The Journal of Korean Academy of Prosthodontics
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• v.41 no.6
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• pp.747-761
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• 2003

Statement of problem. The proper materials of attachments for implant retained overdenture are unknown, such as the correlation between retention and abrasion, as well as the types of materials that are suitable for patrix and for matrix individually. Purpose of this study. The aim of this study was to select a proper clinical attachment system for a successful treatment as well as patient satisfaction. Methods. Retention and abrasion of 14 commercial attachments were measured during 15,000 removes. Results. A retentive part (matrix) which requires elasticity has to be made of gold while the patrix part which does not require elasticity has to be made of titanium. This gold matrix / titanium patrix combination showed the most retentive force and the least retention loss.

• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.42 no.5
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• pp.24-30
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• 2010

Papermaking technology has drastically improved over the last 20 years to face new challenges. Because environmental regulations have become increasingly strict, papermaking systems have had to accommodate elevated recycled pulp content and an increased use of recycled process water. Process water in papermaking systems has become more dirtier and reduced polymer efficiency. Amphoteric PAM demonstrated a higher degree of stability in a high conductivity environment compared to cationic PAM. This was illustrated by the improved retention performance, particularly the ash retention. This amphoteric polymer can be used for board or newsprint production using recycled pulp, especially for the systems where polymer dissolving water is high in conductivity and degradation of cationic functional groups of cationic PAM can occur.

• The Journal of the Korea Contents Association
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• v.13 no.12
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• pp.974-985
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• 2013

This research aimed to propose policy alternatives on acquisition and retention of SME's R&D personnel through the analysis of the status and problems of SME's R&D personnel. As research methods, literature review, survey analysis, domestic and foreign R&D personnel support system and practices benchmarking, human capital corporate panel (HCCP) and integrated survey DB material analysis, and case investigation by interview were used. The occupational status and problems of SME R&D personnel concerned on the corporate size, HRM practices on satisfaction and HRD problems, talent personnel management and training system status, the core talent management system and R&D personnel management system, and its complaints were organized. As conclusion, we have proposed alternatives on acquisition and retention of R&D personnel focused on the talent management. Suggestions were such as supports on R&D personnel management system and its dissemination, systematic career development programs, and excellency promotion on SME's and R&D talent personnel.