• 제목/요약/키워드: Defect structures

검색결과 410건 처리시간 0.025초

Structural Evolution and Electrical Properties of Highly Active Plasma Process on 4H-SiC

  • Kim, Dae-Kyoung;Cho, Mann-Ho
    • Applied Science and Convergence Technology
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    • 제26권5호
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    • pp.133-138
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    • 2017
  • We investigated the interface defect engineering and reaction mechanism of reduced transition layer and nitride layer in the active plasma process on 4H-SiC by the plasma reaction with the rapid processing time at the room temperature. Through the combination of experiment and theoretical studies, we clearly observed that advanced active plasma process on 4H-SiC of oxidation and nitridation have improved electrical properties by the stable bond structure and decrease of the interfacial defects. In the plasma oxidation system, we showed that plasma oxide on SiC has enhanced electrical characteristics than the thermally oxidation and suppressed generation of the interface trap density. The decrease of the defect states in transition layer and stress induced leakage current (SILC) clearly showed that plasma process enhances quality of $SiO_2$ by the reduction of transition layer due to the controlled interstitial C atoms. And in another processes, the Plasma Nitridation (PN) system, we investigated the modification in bond structure in the nitride SiC surface by the rapid PN process. We observed that converted N reacted through spontaneous incorporation the SiC sub-surface, resulting in N atoms converted to C-site by the low bond energy. In particular, electrical properties exhibited that the generated trap states was suppressed with the nitrided layer. The results of active plasma oxidation and nitridation system suggest plasma processes on SiC of rapid and low temperature process, compare with the traditional gas annealing process with high temperature and long process time.

회음 천공지 기저 도서형 피판을 이용한 회음부 재건 (Perineal Reconstruction with the Perineal Perforator Based Island Flap)

  • 이혜민;김정태;황원중
    • Archives of Plastic Surgery
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    • 제32권1호
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    • pp.105-109
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    • 2005
  • Perineal area is composed of compact structures of urogenital organs and anus requiring a more sophisticated selection of flap and reconstruction. For achieving better outcome then conventional flap surgery, we use the perineal perforator based island flap for its reconstruction. After locating the perforator by Doppler, the flaps were designed according to the defect or expected vaginal orifice. The flaps were elevated bilaterally as island pattern. Finally defect or neovagina was reconstructed with inconspicious linear scar hidden in the inguinal crease. Five cases were performed with the perineal perforator based island flap. There were 3 cases of vulvar cancer, 1 case of transsexualism, and 1 case of ambiguous genitalia because of congenital adrenal hyperplasia. Operative results were satisfactory with good contouring and less prominent donor scar, when they were compared with other flap reconstructions such as latissimus dorsi perforator flap, groin flap, gracilis myocutaneous flap etc. The perineal perforator based island flap is highly recommended with the advantages of easy flap elevation, good rotation arc, and appropriate flap thickness for contouring. Compared with other conventional flaps, it can be selected as a good option for moderate defect of perineal area.

X선 조사에 의해 (Ba, Sr) FBr : Eu 형광 물질에 생성되는 결함 특성 (Defect Analysis of Phospher (Ba, Sr) FBr : Eu by X-Ray Irradiation)

  • 신중기;이종용;배석환;김재홍;권준현
    • 한국재료학회지
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    • 제18권8호
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    • pp.427-431
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    • 2008
  • The mechanical property of a phosphore layer was investigated by measuring the resolution (LP/mm) and by positron annihilation spectroscopy and SEM. Image plate samples containing the phosphore layer were irradiated by X-rays in a hospital numerous times over a course of several years. The LP/mm values of a (Ba,Sr)FBr : Eu image plate irradiated by X-rays varied between 2.2 and 2.0 over a period of four years. Coincidence Doppler Broadening (CDB) positron annihilation spectroscopy was used to analyze defect structures. The S parameters of the samples from hospital use varied from 0.6219 to 0.6232. There was a positive relationship between the time of exposure to the X-rays and the S parameters. Most of the defects were found to have been generated by X-rays.

Structure and optical properties of vapor grown In2O3: Ga nano-/microcrystals

  • Sanchez, Diego Leon;Ramon, Jesus Alberto Ramos;Zaldivar, Manuel Herrera;Pal, Umapada;Rosas, Efrain Rubio
    • Advances in nano research
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    • 제3권2호
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    • pp.81-96
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    • 2015
  • Octahedral shaped single crystalline undoped and Ga-doped indium oxide nano-and microcrystals were fabricated using vapor-solid growth process. Effects of Ga doping on the crystallinity, defect structure, and optical properties of the nano-/microstructures have been studied using scanning electron microscopy, microRaman spectroscopy, transmission electron microscopy and cathodoluminescence spectroscopy. It has been observed that incorporation of Ga does not affect the morphology of $In_2O_3$ structures due to its smaller ionic radius, and similar oxidation state as that of In. However, incorporation of Ga in high concentration (~3.31 atom %) causes lattice compression, reduces optical band gap and defect induced CL emissions of $In_2O_3$ nano-/microcrystals. The single crystalline Ga-doped, $In_2O_3$ nano-/microcrystals with low defect contents are promising for optoelectronic applications.

DBPAS를 이용한 CaWO4 결정의 결함특성 (The Defect Characterization of CaWO4 Crystals by Doppler Broadening Positron Annihilation Spectroscopy)

  • 김창규;안창모;송기영;이종용
    • 한국재료학회지
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    • 제12권5호
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    • pp.359-362
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    • 2002
  • DBPAS has been used to characterize atomic level defect structures in materials. In this investigation the numerical analysis of the Doppler spectra was restricted to the determination of the shape parameter, S, defined as the ratio between the total amount of counts in a central portion of the spectrum and the total amount of counts. As samples were exposed by X-ray increasing from 3, 6, and 9 Gy with 6 MV, and 10 MV each and also by E-beam increasing the energies with 6 MeV, 9 MeV, 12 MeV, and 20 MeV. The S-parameter values were increased as increasing the exposed time and the energies. The S-parameters of the large and small size grains in $CaWO_4$ were measured. The S-parameter of the small size grains in $CaWO_4$ was resulted in larger values.

The effects of temperature and vacancy defect on the severity of the SLGS becoming anisotropic

  • Tahouneh, Vahid;Naei, Mohammad Hasan;Mashhadi, Mahmoud Mosavi
    • Steel and Composite Structures
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    • 제29권5호
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    • pp.647-657
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    • 2018
  • Geometric imperfections may be created during the production process or setting borders of single-layer graphene sheets (SLGSs). Vacancy defects are an instance of geometric imperfection, so investigating the effect of these vacancies on the mechanical properties of single-layer graphene is extremely important. Since very few studies have been conducted on the structure of imperfect graphene (with the vacancy defect) as an anisotropic structure, further study of this defective structure seems imperative. Due to the vacancy defects and for the proper assessment of mechanical properties, the graphene structure should be considered anisotropic in certain states. The present study investigates the effects of site and size of vacancy defects on the mechanical properties of graphene as an anisotropic structure using the lekhnitskii interaction coefficients and Molecular Dynamic approach. The effect of temperature on the severity of the SLGS becoming anisotropic is also investigated in this study. The results reveal that the amount of temperature has a big effect on the severity of the structure getting anisotropic even for a graphene without any defects. The effect of aspect ratio, temperature and also size and site of vacancy defects on the material properties of the graphene are studied in this research work. According to the present study, using material properties of flawless graphene for imperfect structure can lead to inaccurate results.

Inhomogeneous bonding state modeling for vibration analysis of explosive clad pipe

  • Cao, Jianbin;Zhang, Zhousuo;Guo, Yanfei;Gong, Teng
    • Steel and Composite Structures
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    • 제31권3호
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    • pp.233-242
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    • 2019
  • Early detection of damage bonding state such as insufficient bonding strength and interface partial contact defect for the explosive clad pipe is crucial in order to avoid sudden failure and even catastrophic accidents. A generalized and efficient model of the explosive clad pipe can reveal the relationship between bonding state and vibration characteristics, and provide foundations and priory knowledge for bonding state detection by signal processing technique. In this paper, the slender explosive clad pipe is regarded as two parallel elastic beams continuously joined by an elastic layer, and the elastic layer is capable to describe the non-uniform bonding state. By taking the characteristic beam modal functions as the admissible functions, the Rayleigh-Ritz method is employed to derive the dynamic model which enables one to consider inhomogeneous system and any boundary conditions. Then, the proposed model is validated by both numerical results and experiment. Parametric studies are carried out to investigate the effects of bonding strength and the length of partial contact defect on the natural frequency and forced response of the explosive clad pipe. A potential method for identifying the bonding quality of the explosive clad pipe is also discussed in this paper.

A propeller superficial transverse cervical artery perforator flap for defect coverage of the submental area: a case report

  • Choi, Jong Yun;Seo, Jeong Hwa;Cha, Won Jin;Seo, Bommie Florence;Jung, Sung-No
    • 대한두개안면성형외과학회지
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    • 제22권6호
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    • pp.341-344
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    • 2021
  • Reconstruction of submental defects is a challenge that needs to be approached carefully, since many important anatomical structures are located in this small space. Both aesthetic and functional outcomes should be considered during reconstruction. In this report, we describe a case where a superficial branch of the transverse cervical artery (STCA) perforator propeller flap was applied for coverage of the submental area. An 85-year-old woman presented with a 3-cm ovoid mass on her submental area. We covered the large submental defect with a STCA rotational flap in a 180° propeller pattern. The flap survived well without any complications at 1 year of followup. A STCA propeller flap is a useful surgical option in reconstruction for defect coverage of the submental area.

Maxillo-mandibular Defect Reconstruction with Bilateral Free Fibula Flaps with Dental Implant Placement and Immediate Loading: A Case Report of the Three-team Approach

  • Nazarian, David;Dikarev, Aleksei;Mokhirev, Mikhail;Zakharov, Georgy;Fedosov, Alexander;Potapov, Maksim;Chernenkiy, Mikhail;Vasilev, Yuriy;Kyalov, Grigoriy;Chausheva, Saniyat;Khachatryan, Arbak;Tevosyan, Artur;Arakelyan, Gevorg
    • Archives of Plastic Surgery
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    • 제49권5호
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    • pp.652-655
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    • 2022
  • Patients with advanced malignant tumors, including both jaws, is a challenging task for a head and neck surgeon. Current treatment landscape demonstrates good functional, anatomical, and aesthetic results in patients who could previously receive only palliative care. The extensive tissue defects resulting from oncological resections in the head and neck region require immediate reconstruction due to the exposure of vital structures and their contact with the external environment. A patient was operated using a three-team multidisciplinary approach involving simultaneous work of three specialized teams of maxillofacial and reconstructive microsurgeons, as well as an implantologist and a prosthodontist. This approach allowed simultaneous tumor resection with subsequent reconstruction of the intraoperative defect involving bilateral harvesting of two revascularized free fibular osteomusculocutaneous flaps with dental implantation and simultaneous rehabilitation of dentition with crowns.

전이학습 기반 콘크리트의 다양한 결함 분류에 관한 연구 (A study on the classification of various defects in concrete based on transfer learning)

  • 윤영근;오태근
    • 문화기술의 융합
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    • 제9권2호
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    • pp.569-574
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    • 2023
  • 콘크리트 구조물의 적절한 유지관리를 위해서 다양한 결함에 대해 사전에 파악하고 유지관리하는 것이 필요하다. 현재 방법으로는 규모가 큰 사회기반시설물의 점검 시 효율성, 안전성, 신뢰성에 문제가 있어 새로운 점검 방식의 도입이 필요하다. 최근에는 영상에 대한 딥러닝 기술이 발달함에 따라 콘크리트 결함 분류 연구가 활발히 진행되고 있다. 하지만, 균열 외에 오염과 박락 등에 대한 연구는 제한적이다. 본 연구에서는 사전에 학습된 딥러닝 모델에 대한 전이학습을 통한 다양한 콘크리트 결함 유형 분류 모델을 개발하고, 정확도를 저하시키는 요인을 도출 및 향후 발전 방향을 제시하였다. 이는 향후 콘크리트 유지관리 분야에서 활용도가 높을 것으로 예상된다.