• Proceedings of the Korean Society of Precision Engineering Conference
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• 2006.05a
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• pp.203-204
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• 2006

Studies on some biodegradable polymers and other materials such as hydrogels have shown the promising potential for a variety of surgical applications. Postoperative adhesion caused by the natural consequence of surgical wound healing results in problems of the repeated surgery. Recently, scientists have developed absorbable anti-adhesion barriers that can protect a tissue from adhesion in case they are in use; however, they are dissolved when no longer needed. Although these approaches have been attempted to fulfill the criteria for adhesion prevention, none can perfectly prevent adhesions in all situations. Overall of this work, a new method to fabricate an anti-adhesion membrane using biodegradable polymer and hydrogel has been developed. The ideal barrier for preventing postoperative adhesion would have the following properties; it should be (i) resorbable (ii) non-reactive (iii) easy to apply (iv) capable of being fixed in position. In order to fulfill these properties, we adopted solid freeform fabrication method combined with surface modification which includes the hydrogel coating, therefore, inner or outer structure can be controlled and the property of anti adhesion can be improved.

• Membrane Journal
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• v.34 no.1
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• pp.20-29
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• 2024

Membranes are increasingly used in a variety of applications including desalination, gas separation, disposable filters, and healthcare products. Recently, sustainable and green membrane fabrication technology is recognized as one of the decisive initiatives to reach the target of pollution control. Especially, the fabrication of bio-based membranes using such as poly lactic acid (PLA), polybutylene adipate terephthalate (PBAT), and polybutylene succinate (PBS) has attracted considerable attention. The phase inversion method is one of the versatile approaches for preparing PLA membranes. This article reviews the recent advances in PLA membrane preparation via the phase inversion method. Furthermore, it provides a perspective on the potential outlook for future advances. Overall, this review has demonstrated has been conducted in the area of bio-based PLA membranes.

• Journal of Periodontal and Implant Science
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• v.27 no.1
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• pp.129-150
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• 1997

The purpose of this study was to evaluate the effects of tetracycline(TC}, flurbiprofen, and PDGF-BB loaded biodegradable membranes on the cell-attachment, the activity of loaded PDGF-BB, in vivo release kinetics, and guided bone regenerative potentials. To evaluate the cell attachment to membranes, the number of gingival fibroblasts attached to each membrane(10% TC, 10% flurbiprofen, $200ng/cm^2$ PDGF-BB loaded membranes, drug-unloaded membrane) was counted by coulter counter and the morphologic pattern of attached cells was examined under SEM. To determine whether the activity of loaded PDGF-BB is sustained, the cellular growth and survival rate of gingival fibroblasts was used for both standard PDGF-BB and loaded PDGF-BB. For evaluation of in vivo release kinetics, drug-loaded membranes were implanted on the dorsal skin of the rats. On 1, 3, 7, 10, 14, 21, and 28 days after implantation, the amount of remaining drugs were measured by HPLC assay for TC and flurbiprofen, and by ${\gamma}-scintillation$ counter for $PDGF-BB^{1125}$. For evaluation of guided regenerative potential, the amount of new bone in the calvarial defect(5mm in diameter) of the rat was measured by histomorphometry 1 and 2 weeks after implantation of membranes. The number of cells attached to the PDGF-BB loaded membrane was largest as compared with the other mernbranes.(p< 0.05) The activity of loaded PDGF-BB was not significantly different from the activity of standard PDGF-BB.(p<0.05) After initial burst release of drug during the first 24 hours, drugs were gradually released for 4 weeks. Especially the release rate of PDGF-BB was nearly constant during 4 weeks. PDGF-BB loaded membranes(200, $400ng/cm^2$) were effective in guided bone regeneration as compared with drug-unloaded membrane. These results implicate that drug-loaded biodegradable membranes might be a useful for guided bone regeneration.

• Journal of radiological science and technology
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• v.37 no.1
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• pp.15-20
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• 2014

This study was to evaluate clinical feasibility of biodegradable polymeric membrane for interventional procedure in preliminary study. Bio-degradable polymetric membrane was produced into a solution by mixing hyaluronic acid powder with NaOH solution in a heating mantle. Three different concentrations of contrast media (10, 20, and 30 vol%) were added to the produced soluble powder, and vertical agitation was performed for 12 hours at a speed of 100 to 200 rpm at a room temperature. It was freeze dried for 24 hours at a temperature $80^{\circ}C$. Pressure on the freeze dried sample was exerted by a hydraulic press in order to form the freeze dried sample into a membrane. The membrane produced with varying contrast medium concentration was visually examined by a scanning electron microscope and radiographically inspected. Under the visual examination, the higher the concentration of contrast medium, the rougher the surface. Radiographic transparency was similar under all conditions of fluoroscopic radiography, simple radiography, and serial radiography. In conclusion, this preliminary study verified that bio-degradable membrane produced with hyaluronic acid was a material with clinical usability.

• Journal of Periodontal and Implant Science
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• v.25 no.2
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• pp.301-320
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• 1995

The purpose of this study was to evaluate a new biodegradable membrane - atelocollagen as a guided tissue regeneration barrier on the dehiscence defects adjacent to the dental implants. 3 beagle dogs were selected for this study and all the mandibular premolars($P_1,P_2,P_3&P_4$) were extracted. Twelve weeks after the extraction, the edentulous ridges were formed to be placed the titanium plasma-sprayed IMZ implants. Four implant osteotomies were performed on each side of the mandible. The osteotomies were placed facially in the edentulous ridges to approximate an actual dehiscence defect as closely as possible, The standardized dehiscence defects were created 3 mm in width and 4 mm in height by osteotomy. A total 24 implants were placed. e-PTFE, ateloco11agen and $Collatape^{(R)}$ were placed to cover the defects and the one defect served as a control, not covered any membrane. By random selection, three dogs were sacrificed at 2 weeks, 4weeks and 8 weeks after fixation with 3% glutaraldehyde. A week before sacrificing, 8-week dog was infused intravenously with oxy-tetracycline 30mg/kg. The left mandibular blocks were used for full decalcified histologic preparation and the right mandibular blocks were selected for undeca1cified preparation, At 2 weeks, the regenerated bone of e-PTFE and atelocollagen groups appeared to be more dense than other groups and the percentage of bone defect fill was highest for e-PTFE and follwed by ateloco1lagen group. However, the $Collatape^{(R)}$ and control groups showed a little new bone formation. $Collatape^{(R)}$ was almost degraded within 2 weeks. At 4 weeks, the regenerated new bone were much greater and denser than at 2 weeks for e-PTFE and ateloco11agen group. Although a part of atelocollagen bagan to be degraded at the margin and surrounded by foreign body giant cells related to foreign body reaction, it was generally intact and the regenerated new bone was shown much more than at 2 weeks. The amount of new bone in $Collatape^{(R)}$ and control groups at 4 weeks were similar to that of 2 weeks group. At 8 weeks, the regenerated bone was matured and observed along the implant fixture. Direct new bone formation and calcium deposits beneath the e-PTFE were observed. No further bone growth was seen in the $Collatape^{(R)}$ and control groups. In reflected fluoromicrcocopic observation, the osteogenic activity was pronounced between e-PTFE membrane and the old bone. High osteogenic activity was also observed in atelocol1agen group. This study suggested that the ateloco11agen as well as e-PTFE could be used for guided tissue regeneration on dehiscence defects adjacent to the dental implants. But the $Collatape^{(R)}$ was completely resorbed within 2 weeks and was not a suitable membrane for guided bone regeneration.

• Membrane Journal
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• v.22 no.6
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• pp.489-501
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• 2012

The nitrogen removal characteristics of the MBR system consisted of two intermittent reactors, a membrane reactor and a deaeration reactor under constant flow and wastewater composition at different operational temperature and SRTs (Sludge Retention Times) were studied by computer simulation. The nitrogen removal efficiencies were dropped from 59% to 31%, when operational temperature was increased to $25^{\circ}C$ from $13^{\circ}C$ with same SRT of 25 days. Lower RBO (Readily Biodegradable Organic) concentrations at intermittent reactors at $25^{\circ}C$ compared with those at $13^{\circ}C$ of operational temperature were believed to be the main cause. The nitrogen removal efficiencies and RBO concentrations at each intermittent reactors were recovered when SRT was reduced to 12.6 days at $25^{\circ}C$. The effect of both SRT and operational temperature on RBO concentrations at intermittent reactors is need to be studied further.

• Journal of Environmental Health Sciences
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• v.32 no.6
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• pp.539-542
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• 2006

The objective of this paper is to compare the applicability of assimilable organic carbon (AOC) or biodegradable dissolved organic carbon (BDOC) for quantifying biodegradable organic material (BOM) and bio-stability in distribution systems for a variety of finished waters. The study the data is derived from was part of an AWWARF and Tampa Bay Water tailored collaboration project to determine the effect of blending different waters on distribution system water quality. Seven different finished waters were produced from surface, ground, or brackish water on site and fed 18 independent pilot distribution systems (PDSs), either as single finished water or as a blend of several finished waters. AOC and BDOC have often been used as indicators of bacterial regrowth potential in distribution systems. In this study, AOC was the more useful assay of the two for the BOM concentrations observed in the PDSs. BDOC did not distinguish BOM while AOC did at the low BOM levels from many of the advanced treatments (e.g. RO, $O^3/BAC$). AOC in contrast allowed much more meaningful calculations of the consumption or production of AOC as the blends passed through the PDSs even for very low BOM blends. In addition, meaningful trends corresponding to changes in heterophic plate count (HPC) were observed for AOC but not for BDOC. Moreover, AOC stability was associated with waters produced from advanced membrane treatment.

• Journal of Periodontal and Implant Science
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• v.27 no.3
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• pp.633-645
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• 1997

The recent trend of research and development on guided tissue regeneration focuses on the biodegradable membranes, which eliminate the need for subsequent surgical removal. They have demonstrated significant and equivalent clinical improvements to the ePTFE membranes. This study evaluate guided tissue regeneration wound healing in surgically induced intrabony periodontal defects following surgical treatment with a synthetic biodegradable membranes, made from a copolymer of glycolide and lactide, in 8 beagle dogs. After full thickeness flap reflection, exposed buccal bone of maxillary and mandibular canine and premolar was removed surgically mesiodistally and occlusoapically at $6mm{\times}6mm$ in size for preparation of periodontal defects. In experimental sites a customized barrier was formed and fitted to cover the defect. Flap was replaced slightly coronal to CEJ and sutured. Plaque control program was initiated and maintained until completion of the study. In 4, 8, 16 and 24 weeks after surgery, the animals were sacrificed and then undecalcified specimens were prepared for histologic evaluation. Histologic examination indicated significant periodontal regeneration characterized by new connective tissue attachment, cementum formation and bone formation. These membranes showed good biocompatibility throughout experiodontal period. The barriers had been completely resorbed with no apparent adverse effect on periodontal wound healing at 24 weeks. These results implicated that present synthetic biodegradable membrane facilitated guided tissue regeneration in periodontal defect.

• Membrane Journal
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• v.10 no.4
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• pp.213-219
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• 2000

In order to resolve the problem of aged land[jlJ leachate treatment, limitation in removal of non-biodegradable materials and denitrification caused by carbon source shortage, we applied combined process consisted of 5MBR and RO to leachate treatment. We perfonned 5MBR pilot plant tests on Yongin City for a period of about lOOdays, demonstrated the performance of the SlVlUR process (($NH_3$-N removal efficiency; 90%). But there was also limitation to removal of non-biodegradable materials and denitrification. In full-scale plant we observed the IXrformance of combined process (SMI3R + R/O) in order to confirm the expected treatment efficiencies. Their results were approximately 98%, 94% of treatment efficiency in case of $COD_{Cr}$(<3 mg/L) and TN(<50 mg/L)respectively and the results of treatment were stable.

• Journal of Periodontal and Implant Science
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• v.37 no.4
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• pp.839-848
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• 2007

Purpose: Various kinds of biodegradable membranes are currently used in dental clinics. And the frequency and the necessity of their usage are increasing due to their numerous advantages. Therefore it is important to understand the difference of various membranes and histological reaction against implanted membranes. Materials and Methods: Biodegradable membranes of $Biogide^{(R)}$, $Resolute^{(R)}$, and $Tutodent^{(R)}$ were cut into small pieces by $1.0{\times}0.5cm$. The membranes were implanted 1.5cm apart from each other under the epithelium on the skull of 18 Sprague Dawley rats. The animals were sacrificed at 3, 7, and 14 days after surgical procedure. The specimens were examined by histological analysis. Results: 1. Early period after implantation of the membranes showed connective tissues surrounding membranes and there were a few inflammatory cells present. 2. In $Biogide^{(R)}$ and $Tutodent^{(R)}$ specimens, inflammatory cells and surrounding tissues were shown to infiltrate from outside with slight density difference inside. In $Resolute^{(R)}$ specimens, membranes were fragmented. Inflammatory cells and connective tissues were also observed inside. 3. In $Resolute^{(R)}$ specimen, giant cells were present which implicates that foreign body reaction has occurred. 4. $Biogide^{(R)}$ had lower integrity than other membranes and is not enough to be used alone in defect area. However, $Resolute^{(R)}$ had superior firmness than others. $Tutodent^{(R)}$ had middle level of integrity. Conclusion: This experimental model enabled to observe early inflammatory reactions and morphological changes of materials and can be used to develop and evaluate the efficacy of biodegradable membranes. Duplication of standardized human oral environment will be required in future experiments.