• 한국정보통신학회:학술대회논문집
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• 한국해양정보통신학회 2001년도 추계종합학술대회
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• pp.363-366
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• 2001

현재 육안에 의한 피혁의 등급 판정 과정은 장시간 시 피로에 의한 일관성 결여로 인해 판정 결과에 대한 신뢰성을 주지 못한다. 따라서 피혁의 품질을 결정하기 위한 객관적인 지표와 이를 기준으로 등급 판정 과정의 자동화가 필요하다. 본 논문에서 적용된 피혁 자동 선별 시스템은 피혁에 대한 정보를 취득하는 과정과 이들 정보로부터 등급을 판정하는 과정으로 구성된다. 피혁의 품질은 조밀도와 결함의 종류 및 분포도와 같은 피혁 정보에 의해 결정된다. 본 논문에서는 디지털 카메라에 의해 획득된 흑백 영상으로부터 피혁의 조밀도 및 결함에 대한 정보를 추출하는 알고리즘을 제안한다. 조밀도에 대한 정보는 원 영상을 주파수 영역으로 변환한 후 나타나는 퓨리에 스펙트럼 분포의 특징 값들에 의해서 추출된다. 그리고 결함에 대한 정보는 전처리 과정을 거친 영상으로부터 경계선 검출 후 검색 윈도우를 사용하여 윈도우에 해당하는 픽셀들의 통계적 수치에 의해서 검출된다. 피혁 전체에 대한 정보들은 피혁의 등급을 판정하는 지표로 사용되며 실제 머신 비젼 시스템에 적용된다.

• 한국진공학회:학술대회논문집
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• 한국진공학회 1997년도 제12회 학술발표회 논문개요집
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• pp.47-48
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• 1997

• 한국결정성장학회지
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• 제9권2호
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• pp.157-161
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• 1999

초크랄스키 실리콘 기판의 뒷면에 형성된 기계적 손상이 미치는 효과에 대하여 고찰하였다. 기계적 손상의 정도는 레이저 여기/극초단파 반사 광전도 감쇠법에 의한 소수반송자 재결합 수명, 습식산화/선택적 식각 방법, 표면 부위 미소 결함 및 X-선 단면 측정 분석으로 평가하였다. 그 결과, 웨이퍼 뒷면에 가해지는 기계적 손상의 세기가 강할수 록 소수반송자 재결합 수명은 짧아지고, 표면 부위 미소 결함 밀도는 비례적으로 증가하였으며, 산화 유기 적충 결함 밀 도와도 상호 일치하였다. 그래서, 표면 부위 미소 결함 기술은 산화 유기 적층 결함을 측정하는데 있어서 통상적인 부식 방법과는 별도로 사용될 수 있다.

• 한국생산제조학회지
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• 제19권1호
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• pp.57-64
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• 2010

Metal Injection Molding (MIM) is attractive because it produces consistent, complex-geometry components for high-volume, high-strength, and high-performance applications. Also MIM using in optical communication field, display field, and semi-conductor field is a cost-effective alternative to metal machining or investment casting parts. It offers tremendous single-step parts consolidation potential and design flexibility. The objective of this paper is to study the suitability of design, flow analysis, debinding and sinterin processes, and capability analysis. The suitable injection conditions were 0.5~1.5 second filling time, 11.0~12.5 MPa injection pressure derived from flow analysis. The gravity of the product is measured after debinding an sintering. The maximum and minimum gravity levels are 7.5939 and 7.5097. the average and standard deviation are 7.5579 and 0.0122; when converted into density, the figure stands at 98.154%. According to an analysis of overall capacity, PPM total, which refers to defect per million opportunities(DPMO), stands at 166,066.3 Z.Bench-the sum of defect rates exceeding the actual lowest and highest limits-is 0.97, which translates into the good quality rate of around 88.4% and the sigma level of 2.47.

• 한국결정성장학회지
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• 제12권6호
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• pp.299-303
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• 2002

The relationship of crystallinity between defects distribution with (100) ZnTe/GaAs using HWE growth was investigated by four crystal rocking curve (FCRC) and transmission electron microscopy (TEM). The thickness dependence of crystal quality in ZnTe epilayer was evaluated. The FWHM value shows a strong dependence on ZnTe epilayer thickness. For the films thinner than 6 ${\mu}{\textrm}{m}$, the FWHM value decreases very steeply as the thickness increases. For the films thicker than 6 ${\mu}{\textrm}{m}$, it becomes an almost constant value. At the thickness of 12 $\mu\textrm{m}$ with the smallest value of 66 arcsec. which is the best value so far reported on ZnTe epilayers was obtained. Investigation into the nature and behavior of dislocations with film thickness in (100) ZnTe/(100)GaAs heterostructures grown by Hot Wall Epitaxy (HWE). This film defects range from interface to 0.7 ${\mu}{\textrm}{m}$ thickness was high density, due to the large lattice mismatch and thermal expansion coefficients. The thickness of 0.7~1.8 ${\mu}{\textrm}{m}$ was exists low defect density. In the thicker range than 1.8 ${\mu}{\textrm}{m}$ thickness was measured hardly defects.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2011년도 춘계학술대회 초록집
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• pp.103.1-103.1
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• 2011

실리콘 이종접합 태양전지에서 계면 결함 밀도는 효율을 결정하는데 가장 중요한 요인으로 작용한다. 계면 결함은 캐리어의 재결합 위치로 작용하여, 계면 결함 밀도가 증가하면 재결합 속도가 증가하게 된다. 흡수층으로 사용되는 실리콘 웨이퍼 (결정질 실리콘)를 가능한 깨끗하게 세정함으로써, 또한 emitter로 쓰이는 비정질 실리콘을 낮은 데미지로 증착하여 계면 결함 밀도를 감소 시킬 수 있다. 이러한 계면 결함 밀도의 감소가 어떠한 변화로 인해 태양전지 특성에 영향을 주는지 시물레이션을 통해 알아보았다. n-type 웨이퍼에 p-type 비정질 실리콘을 emitter로 하여 TCO/p/i/n-type wafer/i/n/TCO/metal의 구조를 적용했고, wafer 전면과 i로 쓰인 무첨가된 비정질 실리콘 간의 계면 결함 밀도를 변수로 적용했다. 그 결과, 계면 결함 밀도가 감소함에 따라 재결합이 감소하여 태양전지 특성이 증가하는 측면도 있지만, 흡수층의 장벽 (barrier height)이 높아져 재결합을 더욱 감소시킴으로 인해 태양전지 특성이 증가함을 알 수 있었다.

• 한국표면공학회지
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• 제36권2호
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• pp.135-140
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• 2003

The difference in lattice parameter and thermal expansion coefficient between GaN and Si which results in many defects into the grown GaN is larger than that between GaN and sapphire. In order to obtain high quality GaN films on Si substrate, it is essential to understand growth characteristics of GaN. In this study, GaN layers were grown on Si(111) substrates by MOCVD at three different GaN growth temperatures ($900^{\circ}C$, $1,000^{\circ}C$ and $1,100^{\circ}C$), using AlN and LT-GaN buffer layers. Using TEM, we carried out the comparative investigation of growth characteristics of GaN by characterizing lattice coherency, crystallinity, orientation relationship and defects formed (transition region, stacking fault, dislocation, etc). The localized region with high defect density was formed due to the lattice mismatch between AlN buffer layer and GaN. As the growth temperature of GaN increases, the defect density and surface roughness of GaN are decreased. In the case of GaN grown at $1,100^{\circ}$, growth thickness is decreased, and columns with out-plane misorientation are formed.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2002년도 하계학술대회 논문집
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• pp.310-313
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• 2002

Structures obtained with a direct boning of two FZ silicon wafers joined in such a way that a smooth surface of one wafer was attached to the grooved surface of the other were studied. A square net of grooves was made with a conventional photo lithography process. After high temperature annealing the appearance of voids and the rearrangement of structural defects were observed with X-ray diffraction topography techniques. It was shown that the formation of void free grooved boundaries was feasible. In the cases when particulate contamination was prevented, the voids appeared in the grooved structures could be eliminated with annealing. Since it was found that the flattening was accompanied with plastic deformation, this deformation was suggested to be intensively involved in the process of void removal. A model was proposed explaining the interaction between the structural defects resulted in "a dissolution" of cavities. The described processes may occur in grooved as well as in smooth structures, but there are the former that allow to manage air traps and undesirable excess of dislocation density. Grooves can be paths for air leave. According to the established mechanisms, if not outdone, the dislocations form local defect arrangements at the grooves permitting the substantial reduction in defect density over the remainder of the interfacial area.

• 한국표면공학회지
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• 제51권1호
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• pp.1-10
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• 2018

Anodic oxidation treatment of metals is one of typical surface finishing methods which has been used for improving surface appearance, bioactivity, adhesion with paints and the resistances to corrosion and/or abrasion. This article provides fundamental principle, type and characteristics of the anodic oxidation treatment methods, including anodizing method and plasma electrolytic oxidation (PEO) method. The anodic oxidation can form thick oxide films on the metal surface by electrochemical reactions under the application of electric current and voltage between the working electrode and auxiliary electrode. The anodic oxide films are classified into two types of barrier type and porous type. The porous anodic oxide films include a porous anodizing film containing regular pores, nanotubes and PEO films containing irregular pores with different sizes and shapes. Thickness and defect density of the anodic oxide films are important factors which affect the corrosion resistance of metals. The anodic oxide film thickness is limited by how fast ions can migrate through the anodic oxide film. Defect density in the anodic oxide film is dependent upon alloying elements and second-phase particles in the alloys. In this article, the principle and mechanisms of formation and growth of anodic oxide films on metals are described.

• 한국임상수의학회지
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• 제25권1호
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• pp.58-63
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• 2008

Peritoneopericardial diaphragmatic hernia(PPDH) is uncommon and congenital disease in dogs and cats. In PPDH, the peritoneal organs such as liver, small intestine, stomach and omentum are displaced into the congenital defect between pericardial sac and diaphragm and cause the abnormal round and enlarged cardiac silhouette. Abnormal cardiac silhouette contacts with the cranial diaphragmatic border consistently and soft tissue- and/or gas- density structures are summated over the cardiac density in radiography. The contrast medium flows from peritoneal cavity into the pericardial sac and demonstrates the herniated abdominal organs and the abnormal defect in positive peritoneography. In this study, 4 dogs was diagnosed as PPDH using radiography, peritoneography and thoracic ultrasonography and showed various clinical signs according to the kind, amount and clinical state of herniated abdominal organs.