• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• 제36권4호
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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.

• Maxillofacial Plastic and Reconstructive Surgery
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• 제21권1호
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• pp.60-64
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• 1999

Recently, for the reconstruction of bony defect and cosmetic improvement, many graft materials and implants have been widely used in the various surgical situations. The alloplastic materials have many advantages such as simplicity of operation, no additional need of surgery, and easy manipulation. The $Medpor^{TM}$(porous high-density polyethylene, Porex Co., USA) was initially studied in 1972 for surgical implant and introduced as an implant material for oral and maxillofacial region by Sauer and King in 1988. This material permits full ingrowth of bone into the implants, substantially increasing the implant's incorporation into the recipient site. It can be shaved during the surgery, which results in an improvement and prefabricated various size and shapes to fit into the surgical defect. The $Medpor^{TM}$ was used in 32 patients from 1995 to 1997 at the maxillofacial region. It was used for paranasal augmentation in 24 cases, for malar augmentation in 2 cases, for infraorbital augmentation in 2 cases, for mandibular angle augmentation in 2 cases, for mandibular body augmentation in 2 cases, for chin vertical augmentation in 1 case. It was mainly fixed with miniplate or screw. There were few complications except one infection and one exposure of the implant.

• 센서학회지
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• 제5권3호
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• pp.25-31
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• 1996

제철소에서 생산되고, 활용되는 빌렛은 두 종류로 나누어, 밀도가 높은 강편 빌렛과 밀도가 낯은 연주 빌렛이 있다. 강편 빌렛은 밀도가 높고 표면이 매끄러워, 비교적 탐상이 용이하였으나, 연주 빌렛은 밀도간 낮고, 표면이 거칠어 탐상이 어려웠다. 연주 빌렛의 탐상도 가능케하기 위하여 초음파 탐촉자의 재질 및 치수등을 개선하고자 하였다. 주요 실험 결과로는, 초음파의 발신용 부분과, 수신용 부분이 서로 나뉘어 있는 분할형 탐촉자를 채택하였으며, 탐촉자의 치수는 탐상체의 치수와 밀접히 관계됨을 알았다. 예로써, 폭/두께가 각각 160mm인 연주 빌렛의 경우, 압전소자의 길이가 21mm, 폭이 8.5mm, 두께가 0.95mm, 인 것 두장이 나란히 내장된 탐촉자가 가장 적당하였다. 소자의 두께에 의존하는 이 때의 중심 주파수는 2.25MHz 였으며, 두 장의 압전소자간 각도에 의존하는 촛점 거리는 70mm 이었다.

• 한국자기학회지
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• 제8권6호
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• pp.346-349
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• 1998

Poly-Si 활성층이 도핑되지 않은 도는 BF2 이온주입으로 도핑된 poly-Si/SiO2 박막에 존재하는 결함을 효과적으로 감소시키기 위하여 저온 rf 수소플라즈마 처리를 수행하였고, 결합의 변화를 전자상자성공명을 이용하여 조사하엿다. 활성층이 도핑되지 않은 시편과 도핑된 시편에서 모두 관측되었던 Pb center와 E' center가 30분의 수소화처리 결과, Pb center의 경우에 각각 80%(도핑되지 않은 시편)와 76% (되핑된 시편)의 큰 결함 감소효과를 얻었으며 E center는 제거되어 관측되지 않았다. 90분의 처리공정에서는 두 시편에서 모두 감소되었던 Pbcenter의 밀도가 다시 증가하였으며, 제거되었던 E' center가 재생되엇다. 특히 도핑된 시편에서의 Pbcenter의 밀도증가가 더욱 민감하게 나타났다.

• 한국전기전자재료학회논문지
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• 제34권4호
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• pp.246-250
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• 2021

TFTs technologies with as high mobility as possible is essential for high-performance large displays. TFTs using nanocrystalline silicon thin films can achieve higher mobility. In this work, the change of the crystalline volume fraction at different hydrogen dilution ratios was investigated by depositing nc-Si:H thin films using PECVD. It was observed that increasing hydrogen dilution ratio increased not only the crystalline volume fraction but also the crystallite size. The thin films with a high crystalline volume fraction (55%) and a low defect density (10¹⁷ cm^-3·eV^-1) were used as top gate TFTs channel layer, leading to a high mobility (55 cm²/V·s). We suggest that TFTs of high mobility to meet the need of display industries can be benefited by the formation of thin film with high crystalline volume fraction as well as low defect density as a channel layer.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2016년도 제50회 동계 정기학술대회 초록집
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• pp.143.1-143.1
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• 2016

Ge is a promising candidate to replace Si in MOSFET because of its superior carrier mobility, particular that of the hole. However Ge oxide is thermodynamically unstable. At elevated temperature, GeO is formed at the interface of Ge and GeO2, and its formation increases the interface defect density, degrading its device performance. In search for a method to surmount the problem, we investigated Ge oxidation through an inert capped oxide layer. For this work, we prepared low doped n-type Ge(100) wafer by removing native oxide and depositing a capping layer, and show that GeO2 interface can be successfully grown through the capping layer by thermal oxidation in a furnace. The thickness and quality of thus grown GeO2 interface was examined by ellipsometry, XPS, and AFM, along with I-V and C-V measurements performed at 100K to 300K. We will present the result of our investigation, and provide the discussion on the oxide growth rate, interface state density and electrical characteristics in comparison with other studies using the direct oxidation method.

• 한국재료학회:학술대회논문집
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• 한국재료학회 2003년도 추계학술발표강연 및 논문개요집
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• pp.26-26
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• 2003

Lithium storage electrodes for rechargeable batteries require mixed electronic-ionic conduction at the particle scale in order to deliver desired energy density and power density characteristics at the device level. Recently, lithium transition metal phosphates of olivine and Nasicon structure type have become of great interest as storage cathodes for rechargeable lithium batteries due to their high energy density, low raw materials cost, environmental friendliness, and safety. However, the transport properties of this family of compounds, and especially the electronic conductivity, have not generally been adequate for practical applications. Recent work in the model olivine LiFePO$_4$, showed that control of cation stoichiometry and aliovalent doping results in electronic conductivity exceeding 10$^{-2}$ S/cm, in contrast to ~10$^{-9}$ S/cm for high purity undoped LiFePO$_4$. The increase in conductivity combined with particle size refinement upon doping allows current rates of >6 A/g to be utilized while retaining a majority of the ion storage capacity. These properties are of much practical interest for high power applications such as hybrid electric vehicles. The defect mechanism controlling electronic conductivity, and understanding of the microscopic mechanism of lithiation and delithiation obtained from combined electrochemical and microanalytical techniques, will be discussed

• 대한전기학회논문지:전기물성ㆍ응용부문C
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• 제54권4호
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• pp.154-160
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• 2005

We have investigated thermal properties showed by changing the content of carbon black which is the component parts of semiconductive shield in underground power transmission cable. Specimens were made of sheet with the nine of those for measurement. Density of specimens was measured by density meter, and then stress-strain of specimens was measured by TENSOMETER 2000. A speed of measurement was 200[mm/min], ranges of stress and strain were 400(Kgf/$cm^2$) and 600[$\%$]. In addition, tests of stress-strain were progressed by aging specimens at air oven. Finally surface profile was shown in order to looking for protrusion of specimens by using smoothness tester. Density was highly measured according to increasing the content of carbon black from this experimental result, and stress was decreased, while strain was increased according to increasing the content of carbon black. And stress-strain were decreased some after aging because of oxidation reaction of chemical defect. Lastly surface of specimens smoothed generally.

• Progress in Superconductivity
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• 제13권3호
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• pp.169-177
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• 2012

Distribution of the local properties in GdBCO and YBCO coated conductors was investigated using Low-temperature Scanning Laser and Hall Probe Microscopy (LTSLHPM). We prepared GdBCO and YBCO coated conductors to study the spatial distribution of the current density in a single bridge. Inhomogeneity of the ${T_c}^{max}$ in the bridge was analyzed from experimental results of Scanning Laser Microscopy (SLM) near the superconducting transition. The local transport and screening current in the bridge were also investigated using Scanning Hall Probe Microscopy (SHPM). A series of line scans of SLM of the GdBCO and YBCO sample showed that lines with more inhomogeneous distributions of ${\delta}V$ had more inhomogeneous distributions of ${T_c}^{max}$. The defect of the superconducting layer of the GdBCO sample caused by damage to the substrate affected the current flow. And we could analyze the redistribution of the current density using SLM and SHPM.

• 열처리공학회지
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• 제31권1호
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• pp.12-17
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• 2018

We investigated the corrosion behavior of commercially pure cold working processed (CP)-Ti with coarse-grained (CG) microstructure heat-treated at $400^{\circ}C$ and $600^{\circ}C$, respectively. It is observed that corrosion resistance of as-received CP-Ti heat-treated at $400^{\circ}C$, at which recrystallization proceeds, is largely improved. Interestingly, the mechanical property of CP-Ti sample at $400^{\circ}C$ was scarcely deteriorated. It is attributed to the decrease of the defects such as strain variance and dislocation density. On the other hand, the annealing treatment at $600^{\circ}C$ of CP-Ti plate causes to grain growth with the noticeable reduction of mechanical property. Hence, it is considered that defect density such as strain and dislocation density is important microstructural parameter for the improvement of corrosion resistance. The introduction of proper annealing treatment can help to improve corrosion resistance without scarifying mechanical property of CP-Ti.