• 한국환경과학회지
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• 제22권1호
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• pp.1-6
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• 2013

A fixed biofilm reactor system composed of anaerobic, anoxic(1), anoxic(2), aerobic(1) and aerobic(2) reactor was packed with synthetic activated ceramic (SAC) media and adopted to reduce the inhibition effect of low temperature on nitrification activities. The changes of nitrification activity at different wastewater temperature were investigated through the evaluation of temperature coefficient, volatile attached solid (VAS), specific nitrification rate and alkalinity consumption. Operating temperature was varied from 20 to $5^{\circ}C$. In this biofilm system, the specific nitrification rates of $15^{\circ}C$, $10^{\circ}C$ and $5^{\circ}C$ were 0.972, 0.859 and 0.613 when the specific nitrification rate of $20^{\circ}C$ was assumed to 1.00. Moreover the nitrification activity was also observed at $5^{\circ}C$ which is lower temperature than the critical temperature condition for the microorganism of activated sludge system. The specific amount of volatile attached solid (VAS) on media was maintained the range of 13.6-12.5 mg VAS/g media at $20{\sim}10^{\circ}C$. As the temperature was downed to $5^{\circ}C$, VAS was rapidly decreased to 10.9 mg VAS/g media and effluent suspended solids was increased from 3.2 mg/L to 12.0 mg/L due to the detachment of microorganism from SAC media. And alkalinity consumption was lower than theoretical value with 5.23 mg as $CaCO_3$/mg ${NH_4}^+$-N removal at $20^{\circ}C$. Temperature coefficient (${\Theta}$) of nitrification rate ($20^{\circ}C{\sim}5^{\circ}C$) was 1.033. Therefore, this fixed film nitrogen removal process showed superior stability for low temperature condition than conventional suspended growth process.

• Journal of Microbiology and Biotechnology
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• 제25권9호
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• pp.1547-1554
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• 2015

The potential of microalgae biofuel has not been realized because of the low productivity and high costs associated with the current cultivation systems. In this study, a new low-cost and transparent attachment material was tested for cultivation of a filamentous algal strain, Stigeoclonium sp., isolated from wastewater. Initially, the different materials tested for Stigeoclonium cultivation in untreated wastewater were nylon mesh, polyethylene mesh, polypropylene bundle (PB), polycarbonate plate, and viscose rayon. Among the materials tested, PB led to a firm attachment, high biomass (53.22 g/m², dry cell weight), and total lipid yield (5.8 g/m²) with no perceivable change in FAME profile. The Stigeoclonium-dominated biofilm consisted of bacteria and extracellular polysaccharide, which helped in biofilm formation and for effective wastewater treatment (viz., removal efficiency of total nitrogen and total phosphorus corresponded to ~38% and ~90%, respectively). PB also demonstrated high yields under multilayered cultivation in a single reactor treating wastewater. Hence, this system has several advantages over traditional suspended and attached systems, with possibility of increasing areal productivity three times using Stigeoclonium sp. Therefore, multilayered attached growth algal cultivation systems seem to be the future cultivation model for large-scale biodiesel production and wastewater treatment.

• 한국패류학회지
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• 제7권1호
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• pp.76-86
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• 1991

A scanning electron microscopic stuey on the glochidial encystment study on the golchidal encystment and excystment of Anodonta fukudai on Acheilognathus yamatsutae, a common natural hostfish, was conducted. The glochidium easily attached to the unscaled surfaces of the host fish such as the fins, lips, and the wall of the buccal cavity. For this study, the fins infected with the glochidia wer mainly observed in a series. The process of encystment was slowly progressed, for 21-25 hours for the early cyst and for 2-4 days for the thick walled cyst. The process of excystmint was visually detected on the 12th day since the attachmint was occurred. The first visible sign was a little tear of the cyst wall covering the hinge and marginal zones of the juvenile clam and once the little sign was appeared the progress of emerging and dettachmint of the juvenile clam from the host was finished relatively in short time. During the process of the encystmint, the cells participationg in covering the attached glochidirm were seened mainly supplied by migration from the surroundings. the shapes of the cells migrating and covering the glochidium were considerably changed and the surface structures of the cells lost their normal pattern of the surface ridges. The unstable forms of the cells were observed almost all throughout the period of the glochidial attachment. No cells of the host epithelium, which were still attached to the juvenile clam energing from the cyst, were observed. The most juvenile clams escaped from the cysts were a little bigger than the glochidia and they were still possessed of the golchidial hooks even though much degenerated. The first growth line was appeared on the shell valves of the juvenild clam when observed right after dettachment.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2007년도 춘계학술대회A
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• pp.409-414
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• 2007

Wettability of solid surfaces with liquids is governed by the chemical properties and the microstructure of the surfaces. We report on the preparation of liquid-repellent surfaces using surface-attached monolayers of perfluorinated polymer molecules on porous silica substrates. A covalent attachment of the polymer molecules to the substrate is achieved by generation of the polymer chains through starting a surface-initiated radical-chain polymerization of a fluorinated monomer. To this, self-assembled monolayers of azo initiators are attached to silica substrates, which are used to kick off the polymerization reaction in situ. The growth of the fluorinated polymer films and the characterization of the obtained surfaces by surface plasmon spectroscopy, XPS, and contact angle measurements is described. It is shown that perfluorinated polymer films can be grown with controlled thicknesses on flat and even on porous silica surfaces, essentially without changing the surface roughness. The combination of the low surface energy coating and the surface porosity allows generation of materials which are both water and oil repellent.

• ALGAE
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• 제25권1호
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• pp.37-44
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• 2010

A tide-simulating apparatus was developed for culturing marine macroalgae. The objective of this study was to introduce a novel tide-simulating apparatus that can simulate a diurnal or semi-diurnal tidal cycle in the laboratory. In this apparatus, the seaweeds are move up and down and the water level remains the same during the simulated tidal cycle. The apparatus consists of 18 cylindrical culture tanks (3 blocks $\times$ 6 culture tanks) with 12 cm diameter and 24.5 cm long containing up to 2.5 L of seawater. There is a horizontal plate which covered all 18 culture tanks, and it is raised and lowered by a programmable motor that can regulate exposure time. In one application, seaweeds are attached to braided twine hung on Plexiglas air-tubing. The air-tubing is attached to a lid that is set on a horizontal plate. This apparatus is made of colorless Plexiglas to maximize light transmittance. This apparatus is easily disassembled and transportable to any indoor laboratory, wet laboratory, greenhouse, etc. This apparatus also offers considerable flexibility in terms of design. The size of culture tank can be redesigned by either increasing the height of cylinder or/and using a different diameter of cylindrical Plexiglas, therefore, larger/taller thalli can be cultivated. Growth rates of three eulittoral Porphyra species from different tidal elevations have been compared using this device.

• 대한의용생체공학회:의공학회지
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• 제13권2호
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• pp.155-164
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• 1992

Attachment and growth of mouse flbroblast cells on block copolypeptides were studied in the pres once or absence of serum proteins. Cells are rapidly attached to she polymer surface within 30 min regardless of substrate in the presence of serum. The number of flbroblast cells attached on the poly mer surface coated by collagen was larger than thats on the bare surface. Attachment of cells Is as a whole suppressed to a low level by the addltion of sodium azide in the absence of serum. Thls suE gests that the active attachment of cells requires the biological metabolism taking place on polymer substrates. In the presence of serum protein, flbroblast cells are more rapidly grown on the bolck co polymer consisting of poly(T-benzyl L-glutamate) (PBLG) and polyoxypropylene(POP) than on other block copolymers. These results were in agreement wish the data obatlned by an Inverted ml croscope.

• Macromolecular Research
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• 제12권4호
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• pp.374-378
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• 2004

The biodegradable and biocompatible poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV), a copolymer of microbial polyester, was fabricated as nanofibrous mats by electrospinning. Image analysis of the electrospun nanofibers fabricated from a 2 wt% 2,2,2-trifluoroethanol solution revealed a unimodal distribution pattern of fiber diameters with an observed average diameter of ca. 185 nm. The fiber diameter of electrospun fabrics could be controlled by adjusting the electro spinning parameters, including the solvent composition, concentration, applied voltage, and tip-to-collector distance. Chondrocytes derived from rabbit ear were cultured on a PHBV cast film and an electrospun PHBV nano-fibrous mat. After incubation for 2 h, the percentages of attached chondrocytes on the surfaces of the flat PHBV film and the PHBV nanofibrous mat were 19.0 and 30.1 %, respectively. On the surface of the electrospun PHBV fabric, more chondrocytes were attached and appeared to have a much greater spreaded morphology than did that of the flat PHBV cast film in the early culture stage. The electro spun PHBV nanofabric provides an attractive structure for the attachment and growth of chondrocytes as cell culture surfaces for tissue engineering.

• 대한소아치과학회지
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• 제23권4호
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• pp.893-898
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• 1996

The occlusal disharmonies resulted from labially protruded or malpositioned teeth can damage the periodontium and induce the non-inflammatory gingival recession. For these cases, a conservative approach was performed by improving oral hygiene and correcting the axial and positional status of the gingivally recessed teeth and removing the prematurely contacted areas. In some cases, rapid remission of tooth mobility and gradual decrease of gingival recession was observed just after start of treatment. In cases of gingival recession in permanent lower incisors of the children with mixed dentition, the treatment of choice is non-surgical conservative approaches. In cases when the gingival inflammation can be controlled through reinforcing the oral hygiene, when attached gingiva have a potential to increase in width through growth (not more than 1 year after eruption or not yet arrived at adult level), and when the recession can be corrected by moving the teeth from labial cortical plate through orthodontic treatment, the conservative measures would be the first choice. On the contrary, when recession has exceeded beyond the level of CEJ, when the gingival inflammation existed with the cause of poor oral hygiene, when the attached gingiva have little potential to increase (for example, more than 8 years after eruption), and when the conservative measures yielded no benefit after 4-8 weeks of treatment, the surgical approaches should be sought.

• Membrane and Water Treatment
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• 제10권1호
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• pp.57-65
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• 2019

This study assessed the contribution of emergent vegetation (Phragmites australis, Typha latifolia, and Nelumbo nucifera) to the submerged surface area, the amount of biofilms attached to the submerged portions of the plants, and the treatment performance of a free water surface (FWS) constructed wetland. Results showed that a 1% increase ($31m^2$) in the vegetative area resulted in an increase of $220m^2$ of submerged surface area, and 0.48 kg Volatile Suspended Solids (VSS) of attached biofilm. As the vegetation coverage increased, effluent organic matter and total Kjeldahl nitrogen decreased. Conversely, a higher nitrate concentration was found in the effluent as a result of increased nitrification and incomplete denitrification, which was limited by the availability of a carbon source. In addition, a larger vegetation coverage resulted in a higher phosphorus in the effluent, most likely released from senescent biofilms and sediments, which resulted from the partial suppression of algal growth. Based on the results, it was recommended that constructed wetlands should be operated with a vegetation coverage of just under 50% to maximize pollutant removal.

• Journal of Ginseng Research
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• 제35권3호
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• pp.375-383
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• 2011

In the previous report, we have demonstrated that ginsenoside Rc, one of major ginsenosides, is a major component for the restoration for normal growth of worms in cholesterol-deprived medium. In the present study, we further investigated the roles of minor ginsenosides, such as ginsenoside $Rh_1$ and $Rh_2$, ginsenoside metabolites such as compound K (CK), protopanaxadiol (PPD), and protopanaxatriol (PPT) and ginsenoside epimers such as 20(R)- and 20(S)-ginsenoside $Rg_3$ in cholesterol-deprived medium. We found that ginsenoside $Rh_1$ almost restored normal growth of worms in cholesterol-deprived medium in F1 generation. However, supplement of ginsenoside $Rh_2$ caused a suppression of worm growths in cholesterol-deprived medium. In addition, CK and PPD also slightly restored normal growth of worms in cholesterol-deprived medium but PPT not. In experiments using ginsenoside epimers, supplement of 20(S)- but not 20(R)-ginsenoside $Rg_3$ in cholesterol-deprived medium also almost restored worm growth. These results indicate that the absence or presence of carbohydrate component at backbone of ginsenoside, the number of carbohydrate attached at carbon-3, and the position of hydroxyl group at carbon-20 of ginsenoside might plays important roles in restoration of worm growth in cholesterol-deprived medium.