• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• 제49권3호
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• pp.163-168
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• 2023

An oroantral fistula (OAF) or oroantral communication (OAC) is an opening between the oral cavity and the maxillary sinus. If left untreated, these openings may cause chronic maxillary sinusitis. Although small defects (diameter <5 mm) may close spontaneously, larger communications require surgical intervention. Various studies have been conducted on OAC closure using a platelet-rich fibrin (PRF) membrane; most of these prior studies have involved simple direct application of PRF clots. This study introduces a new "double-barrier technique" using PRF for closure of an OAF involving sinus mucosal lifting and closure. The PRF material is inserted into the prepared maxillary sinus space, and the buccal advancement flap covers the oral side. This technique was successfully used to treat two patients with chronic OAF in the posterior maxillary region after implant removal or tooth extraction. The use of a PRF membrane in a double-barrier technique may have advantages in soft-tissue healing and could enable easy closure of chronic OAF with minimal trauma.

• Maxillofacial Plastic and Reconstructive Surgery
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• 제31권1호
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• pp.86-91
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• 2009

The success of implants essentially depends on a sufficient volume of healthy bone at the recipient site during implant placement. In patients who have the severe alveolar bone resorption or pneumatized maxillary sinus, it should be performed that bone regeneration procedure before implant placement. Development of barrier membrane makes it possible that predictable result of alveolar bone reconstruction. Many kind of materials used for barrier membrane technique are introduced, non-absorbable or absorbable membranes. But, when operation site was ruptured with membrane exposure, bacterias can be grow up at the bone graft site. Then morphology and migration of fibroblast will be changed. It works as a negative factor on healing process of bone graft site. In oral and maxillofacial department of Chonbuk national university dental hospital, we use variable suture technique like as subgingival suture, vertical mattress suture, simple interrupted suture, if need, tenting suture after GBR or block bone graft. Within these suture technique, wound healing was excellent without complication, so now we take a report of suture technique in reconstruction of alveolar bone surgery.

• 전자공학회논문지
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• 제53권7호
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• pp.11-16
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• 2016

탄화규소(Silicon Carbide)는 와이드 밴드 갭 물질로써 실리콘(Si)에 비해 고전력, 고주파, 고온 소자용 반도체 물질로서 각광받고 있다. 탄화규소를 이용하여 만든 반도체 소자 중 특히 쇼트키 배리어 다이오드는 현재 가장 많이 사용되는 전력반도체 소자로써 스위칭 속도가 매우 빠르고 낮은 온저항 특성을 가지는 소자이다. 하지만 컨텍 엣지에서의 전계집중으로 인해 항복전압이 낮아지는 단점이 있다. 이를 해결하기 위해 다양한 엣지 터미네이션 기술이 제안되고 있는데, 본 논문에서는 최적의 항복전압을 갖기 위한 이중 필드 플레이트(Double Field Plate) 소자 구조를 제안하였다. 측정결과 제작한 소자는 온저항을 유지한 채 38% 향상된 항복전압을 나타내었다. 제안한 소자 특성 검증을 위해 소자를 설계 및 제작한 후 전기적 특성을 측정하였으며, 이중 필드 플레이트 구조는 길이와 두께가 서로 다른 필드 플레이트를 겹쳐 올림으로써 구현하였다.

• 한국표면공학회지
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• 제48권6호
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• pp.260-268
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• 2015

The thermal barrier coating (TBC) for inner wall of liquid-fuel rocket combustor consists of NiCrAlY as bonding layer and $ZrO_2$ as a top layer. In most case, the plasma spray coating is used for TBC process and this process has inherent possibility of cracking due to large difference in thermal expansion coefficients among bonding layer, top layer and metal substrate. In this paper, we suggest crack-free TBC process by using a precise electrodeposition technique. Electrodeposited Ni-P/Cr double layer has similar thermal expansion coefficient to the Cu alloy substrate resulting in superior thermal barrier performance and high temperature oxidation resistance. We studied the effects of phosphorous concentrations (2.12 wt%, 6.97 wt%, and 10.53 wt%) on the annealing behavior ($750^{\circ}C$) of Ni-P samples and Cr double layered electrodeposits. Annealing temperature was simulated by combustion test condition. Also, we conducted SEM/EDS and XRD analysis for Ni-P/Cr samples. The results showed that the band layers between Ni-P and Cr are Ni and Cr, and has no formed with heat treatment. These band layers were solid solution of Cr and Ni which is formed by interdiffusion of both alloy elements. In addition, the P was not found in it. The thickness of band layer was increased with increasing annealing time. We expected that the band layer can improve the adhesion between Cr and Ni-P.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 1995년도 춘계학술대회 논문집
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• pp.47-49
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• 1995

We report the spectroscopic properties of column-III nitrifies of GaN, GaInN, and AlGaN. The column-III nitride semiconductors are promising materials to realize the current-injection-type blue-and ultraviolet (UV)-light-emitting devices with high performance. To acheive the lasing with low threshold, the devices are must constructed to double heterostructure by succesive epitaxial growth technique, and we must confine the carriers in the potential barrier and optical confinement in wave guide between barrier and active layers has different refractive index. The refractive index of column-III nitride semiconductors, however, are rarely reported. The measured refractive index was 2.9, and the observed characteristic peak near the enrgy gap was analysed using a dielectric function and may due to excitonic contribution.

• Progress in Superconductivity
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• 제10권2호
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• pp.99-102
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• 2009

We report our development of the fabrication process of sub-micron scale $Al-AlO_x-Al$ tunnel junction by using electron-beam lithography and double-angle shadow evaporation technique. We used double-layer resist to construct a suspended bridge structure, and double-angle electron-beam evaporation to form a sub-micron scale overlapped junction. We adopted an e-beam insensitive resist as a bottom sacrificing layer. Tunnel barrier was formed by oxidation of the bottom aluminum layer between the bottom and top electrode deposition, which was done in a separate load-lock chamber. The junction resistance is designed and controlled to be 50 $\Omega$ to match the impedance of the transmission line. The junctions will be used in the broadband shot noise thermometry experiment, which will serve as a link between the electrical unit and the thermodynamic unit.

• 한국광학회지
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• 제11권3호
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• pp.193-197
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• 2000

음향파 장벽 구조와 음향광학효과를 이용한 편광모드 변환형 파장가변 광 필터를 LiNbo3와 Ti 이중 확산 공정 기술을 이용하여 제작하였다. 1552.6nm 파장의 TE, TM 입사 편광모드에 대해서 173.07MHz, 173.05MHz의 Rf 주파수에서 81% 이상의 변환효율과 ∼200kHz(∼1.83nm)의 통과대역폭을 얻어Tdmaum 구동파워는 10.97mW로서 음향파 장벽이 없는 광 필터 파워의 10%에 불과 하였다. 파장 변화율과 부 모드 레벨리 각각 8.2nm/MHz와 -4dB로 측정하였다.

• 전자공학회논문지CI
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• 제43권3호
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• pp.20-29
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• 2006

자바 언어는 그 객체지향성, 안전성, 유연성으로 인하여 현재 가장 널리 쓰이는 프로그래밍 언어의 하나가 되었으며, 자바 가상머신이 제공해주는 가비지 컬렉터로 인하여 프로그래머는 메모리 관리에 관한 많은 고민이 줄어들었다. 임베디드 환경에서 역시 자바는 강세를 나타내고 있으며 임베디드 환경의 특성을 반영한 가상 머신과 가비지 컬렉션 기법이 요구되고 있다. 본 논문에서는 힙이라고 불리는 메모리 영역을 크게 젊은 세대와 늙은 세대의 두 부분으로 나누어서 관리하며 각 세대는 그 특성과 요구사항에 적합하도록 각기 다른 기법을 적용한 가비지 컬렉터를 제안한다. 더불어 효과적인 가비지의 식별을 위한 쓰기 장벽과 2중 필터링 기법을 제안하고 있으며, 일반적인 방법으로 회수가 불가능한 순환적 구조의 가비지를 검출하여 회수하기 위한 이중 검사 기법을 제안한다. 제안하는 기법은 임베디드 환경의 요구사항인 객체의 빠른 할당, 동작의 실시간성, 모든 가비지의 회수, 단편화 제거, 높은 지역성 등을 모두 만족한다.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2010년도 제39회 하계학술대회 초록집
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• pp.234-234
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• 2010

The PR transitions in asymmetric dot-in-double-quantum-well (DdWELL) photodetector is identified by bias-dependent spectral behaviors. Discrete n-i-n infrared photodetectors were fabricated on a 30-period asymmetric InAs-QD/[InGaAs/GaAs]/AlGaAs DdWELL wafer that was prepared by MBE technique. A 2.0-monolayer (ML) InAs QD ensemble was embedded in upper combined well of InGaAs/GaAs and each stack is separated by a 50-nm AlGaAs barrier. Each pixel has circular aperture of 300 um in diameter, and the mesa cell ($410{\times}410\;{\mu}m^2$) was defined by shallow etching. PR measurements were performed in the spectral range of $3{\sim}13\;{\mu}m$ (~ 100-400 meV) by using a Fourier-transform infrared (FTIR) spectrometer and a low-noise preamplifier. The asymmetric photodetector exhibits unique transition behaviors that near-/far-infrared (NIR/FIR) photoresponse (PR) bands are blue/red shifted by the electric field, contrasted to mid-infrared (MIR) with no dependence. In addition, the MIR-FIR dual-band spectra change into single-band feature by the polarity. A four-level energy band model is proposed for the transition scheme, and the field dependence of FIR bands numerically calculated by a simplified DdWELL structure is in good agreement with that of the PR spectra. The wavelength shift by the field strength and the spectral change by the polarity are discussed on the basis of four-level transition.

• Journal of Periodontal and Implant Science
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• 제44권3호
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• pp.147-155
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• 2014

Purpose: In the anterior maxilla, hard and soft tissue augmentations are sometimes required to meet esthetic and functional demands. In such cases, primary soft tissue closure after bone grafting procedures is indispensable for a successful outcome. This report describes a simple method for soft tissue coverage of a guided bone regeneration (GBR) site using the double-rotated palatal subepithelial connective tissue graft (RPSCTG) technique for a maxillary anterior defect. Methods: We present a 60-year-old man with a defect in the anterior maxilla requiring hard and soft tissue augmentations. The bone graft materials were filled above the alveolar defect and a titanium-reinforced nonresorbable membrane was placed to cover the graft materials. We used the RPSCTG technique to achieve primary soft tissue closure over the graft materials and the barrier membrane. Additional soft tissue augmentation using a contralateral RPSCTG and membrane removal were simultaneously performed 7 weeks after the stage 1 surgery to establish more abundant soft tissue architecture. Results: Flap necrosis occurred after the stage 1 surgery. Signs of infection or suppuration were not observed in the donor or recipient sites after the stage 2 surgery. These procedures enhanced the alveolar ridge volume, increased the amount of keratinized tissue, and improved the esthetic profile for restorative treatment. Conclusions: The use of RPSCTG could assist the soft tissue closure of the GBR sites because it provides sufficient soft tissue thickness, an ample vascular supply, protection of anatomical structures, and patient comfort. The treatment outcome was acceptable, despite membrane exposure, and the RPSCTG allowed for vitalization and harmonization with the recipient tissue.