• Membrane Journal
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• v.22 no.2
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• pp.95-103
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• 2012

To treat nitrate and non-biodegradable organics effectively in sewage, industrial wastewater and livestock wastewater, the activated sludge process integrated by a membrane separation and a porous electrode- electrolysis was proposed and its efficiency was investigated. The proposed system was consisted of 3 processes; activated sludge, membrane filtration and electrolysis. In the study, the membrane filtration played a role in reducing the load of the electrolysis to operate the proposed process stably. The electrolysis consisted of a porous electrode to increase the efficiency due to the extension of the specific surface area. Additionally, redox reaction in the electrolysis was induced by decomposing influent water as current was applied. As a result, hydrogen free radicals and oxygen radicals as intermediates were produced and they acted as oxidants to play a role in decomposing non-degradable organics. It was environmentally-friendly process because intermediates produced by porous electrode were used to treat waste matters without supplying external reagent. Experimental data showed that the proposed process was more excellent than activated sludge process. SS removal efficiencies of the proposed process, membrane filtration and activated sludge process were about 100%, about 100% and about 90%, respectively. COD removal efficiencies of the proposed system, membrane filtration and activated sludge process were about 92%, about 84% and about 78%, respectively. T-N removal efficiencies of the proposed system, membrane filtration and activated sludge process were about 88%, about 67%, and about 58%, respectively. The SS data showed that SS was efficiently removed in the single of the membrane filtration. The COD/T-N data showed that COD/T-N of membrane hybrid process was treated by removing a little soluble organics and SS, and that COD/T-N of electrolysis hybrid process was treated by oxidize organics with high removal rate.

• Proceedings of the Materials Research Society of Korea Conference
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• 2009.11a
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• pp.41.2-41.2
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• 2009

Electrospinning of Polyvinylalcohol (PVA), Gelatin (GE), and PVA/GE blend solutions in acetic acid were investigated to fabricate biodegradable for tissue engineering. The morphology of the electrospun nanofibers was investigated with a field emission scanning electron microscope. The fibers have average diameters in the range 50-150 nm. The miscibility of PVA/GE blend fibers was examined by differential scanning calorimetry.The PVA and GE were immiscible in the as-spun nanofibrous structure. X-ray diffraction (XRD) determined the crystallinity of the membrane and tensile strength for evaluation physical properties. An in vitro study of PVA/GE blend nanofibers was conducted. To assay the cytocompatibility and cell behavior on the PVA/GE blend nanofibrous scaffolds, cell attachment and spreading of fibroblasts seeded on the scaffolds were studied. Our results indicate that thePVA/GE blend nanofibrous matrix, particularly the one that contained 20% PVA and 80% GE could be a good candidate for tissue engineering scaffolds, because it has an excellent cell attachment and spreading for fibroblast cell.

• Korean Journal of Environmental Agriculture
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• v.25 no.3
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• pp.268-275
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• 2006

ALA (5-aminolevulinic acid) has been proposed as a tetrapyrrole-dependent photodynamic herbicide by the action of the protoporphyrinogen IX oxidase (Protox IX). A study was conducted to determine photodynamic herbicidal effect of ALA on seedling growth of rice (Oryza sativa L.) and barnyard grass (Echinochloa crus-galli Beauv. var. oryzicola Ohwi) under dry and wet conditions. ALA effect on early plant growth of rice and barnyardgrass was greatly concentration dependant, suggesting that it promotes plant growth at very low concentration and inhibits at high concentration. No significant difference in herbicidal activity of biologically and synthetically produced ALAs on plant lengths of test plants was observed ALA exhibited significant photodynamic activity regardless of PSDIP and its duration. Significant shoot growth inhibition by ALA soaking treatment exhibited apparently, indicating that ALA absorbed through root system was translocated into shoot part of plants. ALA reduced plant heights of rice and barnyardgrass seedlings by 6% and 27%, respectively, showing more tolerant to ALA in rice under wet condition. Leaf thickness was reduced markedly by ALA with increasing of ALA concentration, due to mainly membrane destruction and severe loss of turgidity in mesophyll cells, although the epidermal was little affected. It was observed that photodynamic herbicidal activity of ALA applied by pre-and post-emergence application exhibited differently on plant species, and that the activity of ALA against susceptible plants was highly correlated with growing condition.

• Membrane and Water Treatment
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• v.10 no.3
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• pp.213-221
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• 2019

Anaerobic digestion (AD) has been widely used to valorize food waste (FW) because of its ability to convert organic carbon into $CH_4$ and $CO_2$. Korean FW has a high content of fruits and vegetables, and efficient hydrolysis of less biodegradable fibers is critical for its complete stabilization by AD. This study examined the digestates from different anaerobic digesters, namely Rs, Rr, and Rm, as the inocula for the AD of vegetable waste (VW) and cellulose (CL): Rs inoculated with anaerobic sludge from an AD plant, Rr inoculated with rumen fluid, and Rm inoculated with anaerobic sludge and augmented with rumen fluid. A total of six conditions ($3\;inocula{\times}2\;substrates$) were tested in serial subcultures. Biogas yield was higher in the runs inoculated with Rm than in the other runs for both VW (up to 1.10 L/g VS added) and CL (up to 1.05 L/g VS added), and so was biogas production rate. The inocula had different microbial community structures, and both substrate type and inoculum source had a significant effect on the formation and development of microbial community structures in the subcultures. The overall results suggest that the bioaugmentation with rumen microbial consortium has good potential to enhance the anaerobic biodegradability of VW, and thereby can help more efficiently digest high fiber-content Korean FW.

• Journal of Korean Society of Environmental Engineers
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• v.22 no.5
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• pp.959-970
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• 2000

A laboratory-scale experiment was conducted to investigate the effect of soluble microbial products(SMP) on permeate flux in the submerged membrane separation activated sludge process. Continuous and batch filtration test were operated to understand mechanism of relationship between membrane fouling and SMP. Synthetic wastewater(phenol) was used as a carbon source. Hydraulic retention time(HRT) and mixed-liquor volatile suspended solids(MLVSS) of the reactor were kept at 12 hours and 9.000mg VSS/L, respectively. Batch filtration tests ($J_{60}/J_o$) using the mixed liquor from reactor showed that the increase of accumulated SMP concentration in the reactor caused to the decreasing permeate flux and the increasing of the adhesion matters which form cake and gel layer. The resistance value of cake layer was measured $2.9{\times}10^{10}{\sim}4.0{\times}10^{10}(1/m)$, this value showed more significant effect on flux drop than that of among other resistance layers. Batch phenol-degradation experiment was conducted to observe SMP type expected $SMP_{nd}$ and $SMP_{e}$ (SMP resulted from endogenous cell decomposition), these are non-biodegradable high molecular weight organic matter and playa significant role in permeate flux drop. Also, SMP concentration was accumulated as increased of HRT against flux drop.

• Journal of Periodontal and Implant Science
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• v.26 no.3
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• pp.771-778
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• 1996

The assessment of alveolar bone changes on dental radiographs to indicate progression of periodontal diseases or healing response to therapy is routine procedure. However, the diagnostic accuracy in detecting small alveolar bone changes is very limited. Recently, guided bone regeneration therapy is popular, but the quantification of new bone is somewhat difficult with conventional evaluation method. To quantificate the amount of new bone, various evaluating methods have been introduced including histomorphometry, radiomorphometry, biochemical analysis, X-ray probe microanalysis, scanning electron microscope backscatter method. In this study, guided bone regeneration using resorbable membrane with & without PDGF-BB is quatificated through histomorphmetry to evaluate the efficacy of histomorphometric analysis. 4 beagle dogs and 8 Sprague-Dawley rats were selected as experimental animals. In beagle dog experiment, $4{\times}4mm$ Class II defects were created in maxillary both second premolars, and biodegradable membrane containing PDGF-BB(experimental group) were covered over one defect, and same membrane without PDGF-BB(control group) were covered over the other defect. At 2 weeks, 5 weeks after surgery, each beagle dogs were sacrificed, and the tissues were treated by undecalcified fixation. In Sprague-Dawley rat experiment, 5mm round defect were created in temporal bone, the same membranes were covered on the defects. At 1 week, 2 weeks after surgery, each rats were sacrificed, and undecalcified fixation were taken. After grinding tissue specimen, we analyse them histomorphometrically using image analysis system. In beagle dog 2 weeks specimens, new bone formation area were $0.03123mm^2$ in experimental group,and $0.03012mm^2$ in control group. At 5 weeks specimens, $0.15324mm^2$ in experimental group, and $0.09123mm^2$ in control group. In Sprague-Dawley rat specimens, new bone fomation area were $0.20448mm^2$ in 1 week experimental group, $0.03604mm^2$ in 1 week control group. At 2 weeks specimens, $0.46349mm^2$ in experimental group, $0.17741mm^2$ in control group. The results indicated that histomorphometric analysis of new bone formation using image analysis system is very effective quantification method to evaluate the efficacy of treatment modalities.

• KSBB Journal
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• v.21 no.4
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• pp.255-259
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• 2006

The biodegradable hyaluronic acid(HA) membranes cross-linked with lactide using the crosslinking agent, 1-ethyl-3(3-dimethyl aminopropyl) carbodiimide(EDC) were prepared as a potential biocompatible material for tissue engineering. HA membranes having different mechanical properties were synthesised by varying degree of the mole ratio of lactide to HA, EDC concentration, and crosslinking temperature. HA membranes were degradable in water solution and the degradation became slower with the increasing mole ratio of lactide to HA. HA membranes were sterilized using ethylene oxide gas and extracted with cell culture medium for 24 h at $37^{\circ}C$ and 200 rpm. Cytotoxicity of the extract was tested using NIH/3T3 mouse embryo fibroblast as a model cell. Growth inhibition was not observed in the extracts of HA membranes with the mole ratios of lactide to HA, 5 or 10, and 10% EDC concentration, however 11% of growth inhibition was observed in the extract with the mole ratio of 13. Growth inhibition was not observed in the extracts of HA membranes prepared with 5% EDC or 10% EDC and the mole ratio of lactide to HA, 10, however 12% of growth inhibition was observed in the extract with 20% EDC. Cytotoxicity was not observed in the extracts of HA membranes prepared at varying crosslinking temperatures, $15^{\circ}C,\;25^{\circ}C,\;and\;28^{\circ}C$ with the mole ratio of lactide to HA, 10 and 10% EDC.

• The Journal of the Korean dental association
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• v.54 no.5
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• pp.365-373
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• 2016

Purpose: Cemental tear is a specific type of root surface fracture characterized by a complete separation of a cemental fragment along the cementodentinal junction or a partial split within the cementum along an incremental line. It is suggested to be a factor for periodontal or periapical tissue destruction. The aim of this study is to present a diagnosis and treatment of cemental tear associated with periapical lesion with root canal treatment and regenerative periodontal surgery. Treatments: A 60-year-old male who had a history of sports trauma on the mandibular right central incisor about 10 years ago presented with apical cemental tear. Clinical examination showed a slightly dark yellowish discoloration and sinus tract that was located on the apical labial mucosa. The mobility and percussion were also assessed on the diseased tooth and recorded as $Miller^{\circ}{\phi}s$ Class II and tenderness to percussion. The probing depth was within the normal limit (<3 mm). Radiographic examination revealed a radiolucent lesion at the apical area and extended to distal aspect of the tooth along the fragment of cemental tear. After root canal treatment, periapical surgery was performed. The bony defect was exposed and then the detached root fragment was removed. Apical root resection and retrograde filling with Mineral Trioxide Aggregate (MTA) were accomplished and the bony defect was filled with deproteinized bovine bone mineral (DBBM) and covered with biodegradable collagen membrane. Results: After 9-month follow-up, healing of the mandibular right central incisor was uneventful and no swelling, purulence or pain was revealed in the associated area. Probing pocket depth was favorably stable, and the tooth mobility was decreased to the Miller's Class I. Conclusions: Apical cemental tear associated periapical lesion could be successfully treated with removal of the detached cementum in combination with apical surgery and GTR procedure.

• Journal of Environmental Health Sciences
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• v.40 no.2
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• pp.137-146
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• 2014

Objectives: Feasibility of electrochemical oxidation of the aqueous non-biodegradable wastewater such as cationic dye Rhodamine B (RhB) has been investigated in an electrochemical reactor with solid polymer electrolyte (SPE). Methods: Nafion 117 cationic exchange membrane as SPE has been used. Anode/Nafion/cathode sandwiches were constructed by sandwiching Nafion between two dimensionally stable anodes (JP202 electrode). Experiments were conducted to examine the effects of applied current (0.5~2.0 A), supporting electrolyte type (0.2 N NaCl, $Na_2SO_4$, and 1.0 g/L NaCl), initial RhB concentration (2.5~30.0 mg/L) on RhB and COD degradation and $UV_{254}$ absorbance. Results: Experimental results showed that an increase of applied current in electrolysis reaction with solid polymer electrolyte has resulted in the increase of RhB and $UV_{254}$ degradation. Performance for RhB degradation by electrolyte type was best with NaCl 0.2 N followed by SPE, and $Na_2SO_4$. However, the decrease of $UV_{254}$ absorbance of RhB was different from RhB degradation: SPE > NaCl 0.2 N > $Na_2SO_4$. RhB and $UV_{254}$ absorbance decreased linearly with time regardless of the initial concentration. The initial RhB and COD degradation in electrolysis reaction using SPE showed a pseudo-first order kinetics and rate constants were 0.0617 ($R^2=0.9843$) and 0.0216 ($R^2=0.9776$), respectively. Conclusions: Degradation of RhB in the electrochemical reactor with SPE can be achieved applying electrochemical oxidation. Supporting electrolyte has no positive effect on the final $UV_{254}$ absorbance and COD degradation. Mineralization of COD may take a relatively longer time than that of the RhB degradation.

• Journal of Korean Society on Water Environment
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• v.36 no.1
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• pp.55-68
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• 2020

Because of the intensified environmental problems such as climate change and resource depletion, sewage treatment technology focused on energy management has recently attracted attention. The conversion of primary sludge from the primary sedimentation tank and excessive sludge from the secondary sedimentation tank into biogas is the key to energy-positive sewage treatment. In particular, the primary sedimentation tanks recover enriched biodegradable organic matter and anaerobic digestion process produces methane from the organic wastes for energy production. Such technologies for minimizing oxygen demand are leading the innovation regarding sewage treatment plants. However, sewage treatment facilities in Korea lack core technology and operational know-how. Actually, the energy potential of sewage is higher than sewage treatment energy consumption in the sewage treatment, but current processes are not adequately efficient in energy recovery. To improve this, it is possible to apply chemically enhanced primary treatment (CEPT), high-rate activated sludge (HRAS), and anaerobic membrane bioreactor (AnMBR) to the primary sedimentation tank. To maximize the methane production of sewage treatment plants, organic wastes such as food waste and livestock manure can be digested. Additionally, mechanical pretreatment, thermal hydrolysis, and chemical pretreatment would enhance the methane conversion of organic waste. Power generation systems based on internal combustion engines are susceptible to heat source losses, requiring breakthrough energy conversion systems such as fuel cells. To realize the energy positive sewage treatment plant, primary organic matter recovery from sewage, biogas pretreatment, and co-digestion should be optimized in the energy management system based on the knowledge-based operation.