• Journal of Periodontal and Implant Science
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• v.35 no.3
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• pp.687-702
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• 2005

The purpose of this study is to examine the effect of non-resorbable membrane such as e-PTFE which was used with DFDB in bone regeneration on dehiscence defect in peri-implant area. Amomg the patients, who have recieved an implant surgery at the department of Periodontics in Dan Kook University Dental Hospital, 12 patients showed implant exposure due to the dehiscence defect and 15 implants of these 22 patients were the target of the treatment. Periodontists randomly applied $Gore-Tex^{(R)}$ to the patients and treated them with antibiotics for five days both preoperatively and postoperatively. Reentry period was 26 weeks on average in maxilla and 14 weeks on average in mandible. The results were as follows : 1. Dehiscence bone defect frequently appeared in premolar in mandible and anterior teeth in maxilla respectively. 2. Among 15 cases, 1 membrane exposure was observed and in this case, regenerated area was decreased. 3. In non-resorbable membrane, bone surface area $9.25{\pm}4.84$ preoperatively and significantly increased to $11.48{\pm}7.52$ postoperatively(0.05). 4. The increase of bone surface area in non-resorbable membrane was $2.23{\pm}3.38$. 5. As a result of histopathological finding, DFDB surrounded by new bone formation and lamellate bone, resorption of DFDB and bone mineralization was found. Also, fibrosis of connective tissue beneath the membrane was found. This study shows that the surgical method using DFDB and non-resorbable membrane on dehiscence defect in peri-implant area is effective in bone regeneration.

• Journal of Periodontal and Implant Science
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• v.33 no.2
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• pp.193-213
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• 2003

The purpose of this study is to evaluate the phenomenon of attachment and spreading of the cultured rat　calvarial cell inoculated on their surface of different kinds of biodegradable membrane which had been used on tissue regeneration on periodontal defects by using scanning electron microscope. In this experiment 30 Sprague-Dawley male rats (mean BW 150gm) were used to harvest abundant number of cell in the short period. The rats were sacrificed by decapitatioan to obtain the calvaria for bone cell culture. Calvarial cells were cultured with Dulbecco's Modified Essential Medium contained with 10% Fetal Bovine Serum under the conventional conditions. Biodegradable barrier membrane were collected with collagen type, and were divided into 3 different kind of surface such as scattered, polarized and fine-net type as their surface texture. Microcover plate which usually used for cell culture was used as control for smooth surface. All the membrane were seeded with cultured calvarial cell on their surface. The number of cell inoculated on the membrane were $1{\times}10^6$ Cells/ml. After the culture as designed time, all the membrane were washed with 0.1 M Phosphate Buffered saline and fuxed with 2.5% Glutaraldehyde. And all specimen were treated with $OsO_4$, and Tannic acid before drying the cell for coating the cell with gold. Scanning Electron Microscope was used to observation. The following results were obtained. I. During the whole period of experiment, the phenomenon of cell attachment and spreading were revealed similar pattern to compare with smooth surface culture plate and ordinary culture dish. 2. The shape of cell attachment and spreading on the surface of barrier membrane were observed no remarked difference pattern between smooth surface culture plate and ordinary culture dish. 3. The cytoplasmic process of cultured calvaria cell extent to the deep portion of barrier membrane like as their own proper shape. 4. There were no remarkable relationships between the degree of cultured cell spreading and surface structure of barrier membrane. 5. Slight starified layer of cultured calvaria cell were observed on the scattered type of resorbable membrane, Conclusively, this study thus suggest that cultured bone cell inoculated onto the biodegradable barrier membrane may have an important role of carrier for many cell which could be used as new tissue regeneration, and those tissue engeering technique may become an new method in the approach to the repair of bone defects.

• Applied Microscopy
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• v.37 no.4
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• pp.219-230
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• 2007

The morphological effects of intranasal zinc sulfate(5% solution) irrigation on the mouse olfactory epithelium and the regeneration process of olfactory receptor cells following nasal irrigation were studied with scanning and transmission electron microscope. The results were as follows: 1. The septal epithelium except some basal cells was wholly detached from the basement membrane, during the first 6 to 24 hours after 5% zinc sulfate irrigation. 2. 3 days after $ZnSO_4$ treatment, two layered septal epithelium was formed from basal cells. And microvilli were observed in the apical epithelium of newly formed olfactory epithelial cells. 3. 5 days after treatment, a lot of centrosomes and basal bodies were observed in the olfactory receptor cells, and cilia were lined up between microvilli on the apical membrane of olfactory receptor cells. And immature olfactory knob was first observed in the newly formed olfactory receptor cells. Mature olfactory knob was observed 1 week after treatment. 4. There are very many mature olfactory knobs in the olfactory receptor cells 2 weeks after intranasal zinc sulfate irrigation. These results support that treatment with 5% zinc sulfate is a good experimental model for the regeneration of mammalian nervous tissues because this method could thoroughly detach the septal epithelium. During the regeneration of olfactory receptor cells, the surface membrane of the olfactory receptor cells widen the surface with the microvilli. Then cilia, which arranged in a line, substituted for the microvilli. The part of the surface membrane with cilia protruded and finally formed the olfactory vesicle.

• Journal of Advanced Marine Engineering and Technology
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• v.36 no.8
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• pp.1151-1157
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• 2012

Ocean Thermal Energy Conversion(OTEC) technology is one of the new and renewable energy that utilizes the natural temperature gradient that exists in the tropical ocean between warm surface water and the deep cold water, to generate electricity. The selection of working fluid and the OTEC cycle greatly influence the effect on the system operation, and it's energy efficiency and impacts on the environment. Working fluids of the OTEC are ammonia, R22, R407C, and R410A. In this paper, we compared boiling pressure to optimize OTEC system at $25^{\circ}C$. Also, this paper showed net-power and efficiency according to working fluids for closed cycle and regeneration cycle.

• International Journal of Industrial Entomology and Biomaterials
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• v.21 no.2
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• pp.175-179
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• 2010

Silk fibroin membrane was prepared and examined to know the feasibility of SF membrane as guided bone regeneration. The morphology of silk membrane was flat and smooth surface. The conformation of silk fibroin was $\beta$-sheet structure. When the silk membrane was applied on the rat calvarial defect model, it showed significantly higher new bone formation than uncovered control in histomorphometric analysis. The silk membrane was covered by thin fibrotic tissue and there was not observed any inflammatory cells infiltration. In conclusion, silk fibroin membrane could be useful materials for guided bone regeneration.

• The Journal of the Korean dental association
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• v.55 no.7
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• pp.450-456
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• 2017

The purpose of this case report is to present a case of free gingival graft for treatment of mandibular incisor labial gingival recession relapsed after laterally positioned flap surgery. A 22 year-old female patient with discomfort and labial gingival recession on left mandibular central incisor was treated. The patient had been treated root coverage on same site by laterally positioned flap surgery, but treated site had relapsed in one month. Exposed root surface was covered by free gingiva from left palatal area. Although gingival color did not completely match with adjacent gingiva, more than 5mm keratinized gingiva was attained. The patient showed no further recurring pain and recession on gingiva after 5 months from the surgery. In conclusion, the root coverage with gain of keratinized gingiva could be achieved through free gingival graft from palate on relapsed gingival recession.

• Korean Journal of Medicinal Crop Science
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• v.15 no.2
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• pp.73-81
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• 2007

An efficient regeneration system was developed using leaf, petiole, and internode explants. Highly embryogenic callus was obtained following cultivation on MS basal nutrient supplemented with 2 $mg/{\ell}$ 2,4-D. Globular, heart, torpedo and cotyledon shaped somatic embryo were produced from the surface of embryogenic callus. Direct shoot regeneration without intermediate callus formation has been achieved on MS medium supplemented NAA and BAP. The percentage of response varies with different concentration of auxin and cytokinin treated individually or in combination. The best shoot regeneration response (54.28%) and number of shoot per explant (12.67) were achieved on the medium supplemented with 0.1 $mg/{\ell}$ NAA and 1 $mg/{\ell}$ BAP. The regenerated shoot transformed into young plant when cultured into elongation and root induction medium. More than 90% of in vitro propagated plants could survive when transferred to the greenhouse for acclimation. This optimized regeneration system can be used for rapid shoot proliferation and genetic transformation.

• Korean Journal of Environment and Ecology
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• v.37 no.1
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• pp.13-34
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• 2023

Many ecologists try to understand plant communities and societies' changing processes by interacting with environmental factors. Plant communities formed in the sidings of streams, which are more dynamic than forest vegetation, are closely related to the disturbance regime of streams. U. pumila, which forms communities at the edges of streams, is distributed over the central and northern regions of the Korean Peninsula. In this study, we intended to explain the regeneration of U. pumila communities in the upstream region of the Namhangang River. Heights from the stream surface to the mid-high points of communities increased when the age class of U. pumila communities increased. On the other hand, the height of U. pumila tended to increase and decrease as the age class increased. The richness (S), evenness (J'), diversity (H'), and maximum diversity (H'max) also showed a tendency to increase and then decrease as the age class increased. On the other hand, the number of stems per individual and density (D) decreased as the age class increased. Seedlings of U. pumila failed to regenerate in the communities at the intermediate or higher stage of the age class. Regeneration of seedlings occurred in the spaces formed by the flooding, which occurred periodically in streams. After regeneration, U. pumila communities grew like a single organism. On the other hand, the plant species consisting of U. pumila communities exhibited a process in which the S and H' increased and then decreased as they developed. In other words, we determined that the changes in the species compositions were associated with changes in each species' environment and community. A space where seeds can regenerate seedlings should be provided for the regeneration of U. pumila communities. In the mid/upstream region of the Namhangang River, where the present study focused, newly formed communities were rare because the space required to regenerate U. pumila ceased to exist. Accordingly, we suggest securing an appropriate space for the regeneration of seedlings to maintain the U. pumila communities in the upstream region of the Namhangang River.

• Journal of Periodontal and Implant Science
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• v.41 no.5
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• pp.253-258
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• 2011

Purpose: Immediate implantation presents challenges regarding site healing, osseointegration, and obtaining complete soft-tissue coverage of the extraction socket, especially in the posterior area. This last issue is addressed herein using the double-membrane (collagen membrane+high-density polytetrafluoroethylene [dPTFE] membrane) technique in two clinical cases of posterior immediate implant placement. Methods: An implant was placed immediately after atraumatically extracting the maxillary posterior tooth. The gap between the coronal portion of the fixture and the adjacent bony walls was filled with allograft material. In addition, a collagen membrane (lower) and dPTFE membrane (upper) were placed in a layer-by-layer manner to enable the closure of the extraction socket without a primary flap closure, thus facilitating the preservation of keratinized mucosa. The upper dPTFE membrane was left exposed for 4 weeks, after which the membrane was gently removed using forceps without flap elevation. Results: There was considerable plaque deposition on the outer surface of the dPTFE membrane but not on the inner surface. Moreover, scanning electron microscopy of the removed membrane revealed only a small amount of bacteria on the inner surface of the membrane. The peri-implant tissue was favorable both clinically and radiographically after a conventional dental-implant healing period. Conclusions: Secondary closure of the extraction socket and immediate guided bone regeneration using the double-membrane technique may produce a good clinical outcome after immediate placement of a dental implant in the posterior area.

• Journal of Periodontal and Implant Science
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• v.31 no.1
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• pp.193-209
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• 2001

The prognosis of transplanted teeth is strongly related with periodontal healing. Several experimental studies showed that the application of enamel matrix derivatives on periodontitis-affected root surfaces resulted in periodontal regeneration. The purpose of this study was to determine the effect of enamel matrix derivatives on periodontitis-affected root surfaces prior to transplantation in dogs. Class III Furcation defects were surgically created on the left second, the third and the fourth premolar in the mandibles of nine mongrel dogs and experimental periodontitis was induced by placing small cotton pellets into defects for 3 weeks. Periodontitis-affected roots were treated by scaling and planing and the coronal portions were removed. Each root was extracted and implanted into recipient bed prepared in the contralateral premolar area. The transplanted roots were grouped according to the treatment modalities; Group I- roots treated with saline only, Group II- roots conditioned by neutral EDTA, and Group III- roots conditioned by neutral EDTA and enamel matrix derivatives ($EMDOGAIN^{(R)}$, BIORA Co., Sweden). The animals were sacrificed at 1 week, 3 weeks, and 10 weeks after transplantation and decalcified specimens were prepared for histologic examination. In Group I, healing was most frequently characterized by root resorption and ankylosis. In Group II, with root resorption and ankylosis in a few specimens, connective tissue attachment was partly seen on denuded root surface, but no cementum formation was seen. In Group III, there was regeneration by new cementum and periodontal ligament on denuded root surface, although slight root resorption and ankylosis were found in a few specimens. This result suggests that enamel matrix derivatives treatment on periodontitis-aggected root surface could reduce the frequency of root resorption and ankylosis and contribute to periodontal regeneration, and might be useful for autologous transplantation.