• Nuclear Engineering and Technology
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• 제34권3호
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• pp.202-210
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• 2002

The details of the electronic structure of the perfect crystal provides a critically important foundation for understanding the various defect states in uranium dioxide. In order to understand the local defect and impurity mechanism, the calculation of electronic structure of UO$_2$ in the one-electron approximation was carried out, using a semi-empirical tight-binding formalism(LCAO) with and without f-orbitals. The energy band, local and total density of states for both spin states are calculated from the spectral representation of Green’s function. The bonding mechanism in Perfect lattice of UO$_2$ is discussed based upon the calculations of band structure, local and total density of states.

• 한국해양공학회지
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• 제13권4호통권35호
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• pp.45-54
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• 1999

Non destructive test is applied to revise mechanical strength and assume material strength or defect of material, equipment and structure, instead of fracture test. Especially, ultrasonic test has the characteristics such as an excellent permeability high-sensitiveness to fine defect and an almost exact measurement for position, size and direction of inner defect which differ from other non destructive tests. In this study, the program is developed to evaluate optimal testing condition, to distinguish obstacle echo and defect position. This program on the basic of Ray-Tracing model shows generation and processing of ultrasonic pulse. The simulation is compared with testing in the 3 cases of an oblique angle transducer like $45^{\circ},\;60^{\circ}\;and\;70^{\circ}$. The test result for all conditions is well compared with simulation result when relative not is within $0.1{\sim}7.2%$. And the course of several echos is simply assumed through simulation.

• Journal of Chest Surgery
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• 제20권4호
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• pp.760-764
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• 1987

Fifty seven patients underwent repair of a partial atrioventricular septal defect from January 1980 to December 1986. The ostium primum atrial septal defect was closed with autologous or bovine pericardium. The cleft in the anterior mitral leaflet was present in 53 cases, absent in 4 cases. Of the 53 cases with a cleft in the anterior mitral leaflet, 48 received suture repair of the cleft, 3 received mitral valve replacement. There was no hospital death and all the patients were followed-up for a mean period of 26.4 months. Four required permanent pacemaker implantation due to complete heart block, and one of them died of sudden malfunction of pacemaker. Two received reoperation due to significant residual mitral insufficiency. Suture repair of the cleft in the anterior mitral leaflet resulted in significant decrease in degree of mitral regurgitation. During follow-up period 49 patients were in NYHA class I, 7 patients were in NYHA class II. This report suggests that excellent result can be achieved from repair of the partial atrioventricular septal defect by managing the left A-V valve as a bileaflet structure.

• Journal of Welding and Joining
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• 제14권2호
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• pp.90-95
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• 1996

In order to investigate characteristics of surface fatigue crack propagation from a pit shaped surface defect which frequently exists around welded joints, SS400 steel with thickness of 12mm, which has been generally used for structure members, was welded with submerged-arc butt type and machined for both surface. An initial surface defect of pit shape with the aspect ratio of 2 was made on the specimen. The initial defect was located at 5 different zones over the weldment : weld metal zone, boundary between weld metal and HAZ, HAZ, boundary between HAZ and base metal. Characteristics of surface fatigue crack propagation from the defect on each region under the same loading condition were investigated and compared.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2003년도 하계학술대회 논문집 Vol.4 No.1
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• pp.424-427
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• 2003

We have investigated the microstructural analysis of epitaxial lateral overgrowth (ELO), pendeoepitaxy (PE), and superlattice structures used as technology for the reduction of structural defects like dislocation in nitride semiconductors using transmission electron microscopy. We confirmed that the regrowth process such as ELO and PE is very effective technique on the reduction of threading dislocation (less than $10^6/cm^2$) in the specific area. However, to decrease the defect density in the whole nitride films and the suppress the generation of defect by regrowth, we should find the optimized conditions. Besides, the process using double PE and AlGaN/GaN superlattice structure showed no effect on the defect reduction up to now.

• EDISON SW 활용 경진대회 논문집
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• 제6회(2017년)
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• pp.404-411
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• 2017

이 논문에서는 2차원 화합물 반도체인 Indium Selenide monolayer의 효과적인 도펀트 원소를 탐색해보았다. 총 4가지 종류의 원소를 도핑시켜 계산을 했다. In 자리에 Mg과 Sn을 도핑시켜 각각 p-type과 n-type으로 만들고 Se 자리에 As과 Br을 도핑시켜 각각 p-type과 n-type으로 만들었다. 변화한 성질을 알아보기 위해 전자 구조를 분석하고 band structure와 DOS를 살펴보았다. P-type 같은 경우, Mg doped InSe는 shallow defect level이 생겨 좋은 반도체로 쓰일 수 있지만 As을 도핑한 InSe는 deep defect states가 생겼다. VBM에서 약 0.67 eV만큼 떨어져있는데 이 수치는 실험값과 비슷한 값이다. N-type 경우에는 Sn doped InSe는 deep defect states가 생겼고, CBM 아래로 약 0.08eV만큼 defect가 생긴 것이 실험값과 비슷하다. Br doped InSe는 Sn doped InSe보다 안정적인 n형 반도체가 될 수 있다.

• 대한전기학회논문지:전기물성ㆍ응용부문C
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• 제52권10호
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• pp.451-457
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• 2003

The silicon wafer is stable status at room temperature, but it is weak at high temperatures which is necessary for it to be fabricated into a power semiconductor device. During thermal diffusion processing, a high temperature produces a variety thermal stress to the wafer, resulting in device failure mode which can cause unwanted oxide charge or some defect. This disrupts the silicon crystal structure and permanently degrades the electrical and physical characteristics of the wafer. In this paper, the electrical characteristics of a single oxide layer due to high temperature diffusion process, wafer resistivity and thickness of polyback was researched. The oxide quality was examined through capacitance-voltage characteristics, defect density and BMD(Bulk Micro Defect) density. It will describe the capacitance-voltage characteristics of the single oxide layer by semiconductor process and device simulation.

• Nuclear Engineering and Technology
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• 제54권8호
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• pp.2783-2791
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• 2022

Molecular dynamics simulations were performed to predict the behavior of graphite atoms under neutron irradiation using large-scale atomic/molecular massively parallel simulator (LAMMPS) package with adaptive intermolecular reactive empirical bond order (AIREBOM) potential. Defect structures of graphite were compared with results from previous studies by means of density functional theory (DFT) calculations. The quantitative relation between primary knock-on atom (PKA) energy and irradiation damage on graphite was calculated. and the effect of PKA direction on the amount of defects is estimated by counting displaced atoms. Defects are classified into four groups: structural defects, energy defects, vacancies, and near-defect structures, where a structural defect is further subdivided into six types by decision tree method which is one of the supervised machine learning techniques.

• 한국전기화학회:학술대회논문집
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• 한국전기화학회 1998년도 제1회 총회 및 추계학술발표회
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• pp.59-59
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• 1998

• 대한두경부종양학회지
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• 제21권2호
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• pp.190-195
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• 2005

Background and Objectives: Fibula is the flap of choice for reconstruction of wide mandible defects after tumor ablation surgery. In mandible reconstruction, restoring the mandible frame to provide mandibular contour and dental arch while restoring masticatory function are important. Even though vascularized fibula can be osteotomized freely, proper design and flap insetting is not easy because of its three dimensional structure and difference in design according to the defect sites. We reviewed patients who underwent mandible reconstruction with fibular flaps according to the defect sites and suggest proper modification methods of fibular flap according to the various defects sites after tumor ablation surgery. Materials and Methods: Twelve consecutive mandible reconstruction with fibular free flaps were performed for defects after tumor ablation surgery. Patients were classified into 4 groups according to the type of mandibular defect(Group 1 : defect on central segment including symphysis, Group 2 : defect on lateral segment(with or without central segment) confined to body, Group 3 : defect on body and ascending ramus that does not include the condyle, Group 4 : defect including the condyle). Results: We suggest different modification methods of fibular free flap for each patient group. Group 1, 3 ; contour by using multiple closing wedge osteotomy. Group 2 ; single or double barrel reconstruction without wedge osteotomy. Group 4 ; contour using single or multiple wedge osteotomy and condylar reconstruction with costochondral graft. Conclusion: Fibular free flaps can be contoured to any desired shape after multiple osteotomies to restore various mandibular defects. It is a reliable and versatile method for reconstruction of mandibular defects after tumor ablation surgery.