• The Journal of the Korean dental association
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• v.53 no.5
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• pp.348-359
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• 2015

Objective: The aim of this study was to determine the effect of multi-layer of a collagen membrane alone or loaded rhBMP-2 on the buccal plate for ridge preservation after tooth extraction. Material and methods: Following bilateral extraction of the maxillary 1st and 3rd premolars in five dogs, rhBMP-2 loaded collagen membrane was applied to the buccal plates at the 1st premolar and collagen membrane only was applied to the buccal plates at the 3rd premolar unilaterally. The collagen membranes applied in the experimental groups were piled into four layers. The corresponding sites of the contralateral side healed naturally. After 3months of healing, the animals were sacrificed. Radiographic and histologic analyses were performed. Results: There was no significant difference in the healing of extraction socket at both 1st and 3rd premolars. In microcomputed tomography, the widths of the residual ridge of the experimental groups were similar with the controls. Histologically, the experimental groups did not exhibit different pattern compared to the controls regardless of the addition of rhBMP-2. Conclusion: Layering of the collagen membrane with or without rhBMP-2 on the buccal plate failed to show the effectiveness in dimensional preservation of the extraction socket.

• Journal of Periodontal and Implant Science
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• v.37 no.3
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• pp.543-551
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• 2007

When clinicians faced with an insufficient volume of supporting bone on ideally esthetic and bio-mechanical position for dental implantation, guided bone regeneration(GBR) was indicated. Although GBR has wide application at clinic, proper time of membrane removal remains qustionable in using non-resorbable membrane, such as non-expanded polytetrafluoroethylene(PTFE), The aim of this study was to compare the effect of maintenance period of PTFE membrane on bone regeneration in rabbit calvarial defects. Eight adult New Zealand white female rabbits were used in this study. Four defects were surgically made in their calvaria. Using a trephine bur, 4 'through and through' defects were created and classified into 3 groups, which were consisted of control group(no graft), experimental group 1(autogenous bone)and experimental group 2(deproteinized bovine bone; $OCS-B^{(R)}$). The defects were covered with PTFE membrane($Cytoplast^{(R)}$). Membranes were removed after 1, 2, 4 and 8 weeks post-GBR procedure in 2 rabbits repectively, All rabbits were sacrificed after 8 week post-GBR procedure. Specimens were harvested and observed histologically. The results were as follow; 1) The use of graft material and membrane was necessary in GBR procedure. 2) When PTFE membranes were removed early, the most favorable bone regeneration was revealed in experimental group T, followed by experimental group II and control group. 3) On GBR, it is recommended that membrane should maintain for 4 weeks with autogenous graft. As well, the use of xenograft need longer maintenance period than autogenous bone. Further evaluations will be needed, such as histomorphologic research, more species and different kinds of graft materials. And on the basis of these studies, clinical researches would be required.

• Journal of Periodontal and Implant Science
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• v.30 no.3
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• pp.569-584
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• 2000

In order to evaluate the effects of the early exposure of e-PTFE membrane on the periodontal regeneration, 21 cases of 21 patients diagnosed as the chronic adult periodontitis were evaluated. All were class II furcation involvement cases. The control group was composed of 7 cases treated only by the flap operation. 14 cases were treated by the e-PTFE membrane as the experimental group, the membranes of 7 cases were exposed more than 1mm during healing period, which were named as the experimental group I, and the others, experimental group II. Clinical parameters such as probing pocket depth, clinical attachment level, bone probing depth, and gingival recession were recorded before the treatment and 6 months after the treatment. The results were as follows. 1. Significant probing depth reductions were observed for all groups(p<0.05), but no group shows significantly greater reductions than another. 2. Significant clinical attachment gains were observed for the experimental group II(p<0.05), no significant gains were observed in the other groups. 3. Significant bone probing depth reductions were observed for the experimental group II(p<0.05), no significant reductions were observed in the other groups. 4. All but the experimental group II exhibited a significant increase in gingival recession(p<0.05). The result suggested that is case of the e-PTFE membrane is exposed, the result is similar to that of flap operation without membrane. Therefore selecting the proper treatment case, intricate surgical procedure and infection control are essential for minimizing the chance of membrane exposure and finally for the good treatment results.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.39 no.10
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• pp.966-978
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• 2011

Transpiration cooling is the most effective cooling technique for the high-performance liquid rockets and air-breathing engines operating in aggressive environments with higher pressures and temperatures. When applying transpiration cooling, combustor liners and turbine blades/vanes are cooled by the coolant(air or fuel) passing through their porous walls and also the exit coolant acting as an insulating film. Practical implementation of the cooling technique has been hampered by the limitations of available porous materials. But advances in metal-joining techniques have led to the development of multi-laminate porous structures such as Lamilloy$^{(R)}$ fabricated from several diffusion-bonded, etched metal thin sheets. And also with the availability of lightweight, ceramic matrix composites(CMC), transpiration cooling now seems to be a promising technique for high-performance engine cooling. This paper reviews recent research activities of transpiration cooling and its applications to gas turbines, liquid rockets, and the engines for hypersonic vehicles.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.22 no.7
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• pp.595-601
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• 2009

For the silicon oxide $(SiO_x)$ films prepared by using the facing target sputtering (FTS) apparatus that was manufactured to enhance the preciseness of the fabricated thin-film and sputtering yield rate by forming a higher-density plasma in the electrical discharge space for using it as a thin-film passivation system for flexible organic light emitting devices (FOLEDs). The deposition characteristics were investigated under various process conditions, such as array of the cathode magnets, oxygen concentration$(O_2/Ar+O_2)$ introduced during deposition, and variations of distance between two targets and working pressure. We report that the optimum conditions for our FTS apparatus for the deposition of the $SiO_x$ films are as follows: $d_{TS}\;and\;d_{TT}$ are 90mm and 120mm, respectively and the maximum deposition rate is obtained under a gas pressure of 2 mTorr with an oxygen concentration of 3.3%. Under this optimum conditions, it was found that the $SiO_x$ film was grown with a very high deposition rate of $250{\AA}$/min by rf-power of $4.4W/cm^2$, which was significantly enhanced as compared with a deposition rate (${\sim}55{\AA})$/min) of the conventional sputtering system. We also reported that the FTS system is a suitable method for the high speed and the low temperature deposition, the plasma free deposition, and the mass-production.

• Proceedings of the Korea Water Resources Association Conference
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• 2008.05a
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• pp.1939-1943
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• 2008

저수지 수질은 유역의 점오염원 배출부하와 강우시 발생하는 비점오염부하 발생에 의한 유역유출수의 저수지 유입과 저수지내 상황 및 기상등에 많은 영향을 받는다. 이와같이 저수지 수질은 저수지 내외의 다양한 요인에 따라 그 특성을 달리함으로 수질관리를 위해서는 기상, 수리 수문, 수질, 지형, 오염원, 처리시설 등 많은 자료를 필요로 하게 된다. 따라서 각종자료의 입력, 수정 및 분석을 하는 자료관리시스템, 수질모의를 수행하는 모델시스템 그리고 분석결과를 표나 그래프로 표현하는 체계를 하나의 시스템으로 통합 구축하여 필요한 분석을 실시함으로서 여러 가지 대안에 대한 평가를 시각적으로 쉽게 할수 있게 되어 관리자는 보다 정확하고 신속하게 의사결정을 할 수 있게 된다. 본 논문에서는 UML(Unified Model Language)기반 하에서 Visual $C^{++}$ 언어를 사용하여 Class diagram, 화면명세, Database명세 등을 생성하는 체계적인 시스템을 구축하였으며, 수질모의를 위해 유역모델로 HSPF 모형을 선정하였고 저수지 모델로는 CE-QUAL-W2를 적용하였다. 구축된 시스템의 활용을 위해 유역관리 시나리오 4개(하폐수처리장 운영에 따른 수질변화모의, 점오염원 제거시 수질모의, 비점오염원 제거시 수질모의, 개발지 관리에 의한 수질모의)와 저수지관리 시나리오 4개(저수지 운영조건 변화에 따른 수질모의, 조류 차단막 설치에 의한 수질모의, 조류제거선 운영에 따른 수질모의, 빈도강우시 탁수관리 모의)를 적용하여 수질변화를 모의하였으며, 다양한 새로운 시나리오를 원활한 적용할수 있도록 설계하였다. 이상의 적용결과로 평가해 볼 때 본 시스템은 저수지 수질관리에 활용할 수 있는 효율적인 시스템으로 평가되었다.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.27 no.4
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• pp.191-195
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• 2017

The microstructures of nonwoven fabric with and without nanofibers used as a filter for air purification type mask were investigated using scanning electron microscope. Moreover, we proposed a new mask design which is effective in the improvement of the fine dust blocking property. When comparing to nonwoven fabrics of which an average diameter was $25{\mu}m$, the nanofibers formed by the electrospinning process had a tight mesh structure arranged irregularly with a relatively large specific surface area, which could be associated with their much smaller diameter ranging from 25 to 120 nm. Such a prominent structural feature at nanofibers led to mechanical adsorption of fine particles, resulting in enhancement of filtering behavior maintaining high permeability. In addition to the excellent performance of the mask filter, wearing the mask properly is expected to maximize the blocking property of fine dust. To meet such a requirement, a new mask design that can be closely attached to the face in order to effectively block fine dust entering the gap between the face and the mask.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• v.36 no.4
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• pp.275-279
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• 2010

Introduction: Guided bone regeneration (GBR) is a common procedure for the treatment of bone defects and bone augmentation. The nonresorbable barriers are well-documented barriers for GBR because of their stability and malleability. However, few GBR studies have focused on the different types of non-resorbable barriers. Therefore, this study examined the clinical results of different non-resorbable barriers for GBR; expanded polytetrafluoroethylene (e-PTFE) (TR-Gore Tex, Flagstaff, AZ, USA), and high-density polytetrafluoroethylene (d-PTFE) (Cytoplast membrane, Oraltronics, Bremen, Germany). Materials and Methods: The analysis was performed on patients treated with GBR and implant placement from January 2007 to October 2007 in the department of the Seoul National University Bundang Hospital. The patients were divided into two groups based on the type of non-resorbable barrier used, and the amount of bone regeneration, marginal bone resorption after prosthetics, implant survival rate and surgical complication in both groups were evaluated. Results: The implants in both groups showed high survival rates, and the implant-supported prostheses functioned stably during the follow-up period. During the second surgery of the implant, all horizontal defects were filled with new bone, and there was no significant difference in the amount of vertical bone defect. Conclusion: In bone defect areas, GBR with non-resorbable barriers can produce favorable results with adequate postoperative management. There was no significant difference in bone regeneration between e-PTFE and d-PTFE.

• Journal of The Korean Society of Integrative Medicine
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• v.2 no.2
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• pp.41-47
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• 2014

Purpose : The aim was to compare the implant success rate according to membrane type through a clinical case of patients, who used bio-resorbable membrane and non-resorbable membrane. Methods : A survey was conducted targeting patients with the use of bio-resorbable membrane and non-resorbable membrane who visited H dental clinic in Busan for implant surgery and bone graft for 1 year from May 2010 to May 2011. A chart was made and surveyed for 100 people with non-resorbable membrane and for 75 people with bio-resorbable membrane. Results were compared. Results : 1. As for the measurement value of Periotest M${(R)}$, the value of -8~0 was measured with 92% in case of surgery by using non-resorbable membrane. The value of +1~+9 was measured with 8.0%. In case of surgery by using bio-resorbable membrane, Peiotest M(R) was measured with 78.7% as for the value of -8~0 and 16(21.3%) as for the value of +1~+9. In light of this, a case of using non-resorbable membrane was indicated to be higher(p=0.021) in success rate than a case of using bio-resorbable membrane. 2. As a result of periodontal conditions, namely, bleeding(p=0.914), swelling(p=0.500), inflammation(p=0.074), pain(p=0.571), and itch appearance(p=0.475) according to membrane type, all were insignificant. Conclusions : A case of using non-resorbable membrane is considered to be likely to be more effective than using bio-resorbable membrane during GBR(Guided Bone Regeneration) with the use of membrane in implant surgery.

• The Journal of the Korean dental association
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• v.55 no.10
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• pp.676-687
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• 2017

Objectives : The aim of this study was to evaluate the effects of a composite of bone substitute and collagen barrier membrane (bone patch) for local ridge augmentation at peri-implant dehiscence defects on the clinical efficacy and positional stability in dogs. Materials and methods : Implant placement and ridge augmentation procedure were performed at surgically created peri-implant dehiscence defects in canine mandible (n=6). Four treatment modalities were randomly applied: i) bone patch group, ii) Guided bone regeneration (GBR) without pin fixation group (bone graft and collagen membrane), iii) GBR with pin fixation group, and iv) negative control group. After 12 weeks, clinical, micro-CT and histological analyses were performed. Results : Histologic analysis showed that bone patch group had similar results to GBR group and GBR with fixation group in terms of new bone formation. Micro-CT analysis revealed similar results to histologic analysis in terms of total volume maintenance. Operating time was shorter in bone patch group compared to GBR group and GBR with fixation groups. Conclusions : GBR using bone patch could simplify the ridge augmentation procedure with reduced operating time and equivalent biological performance compared to the conventional procedure.