• 대한기계학회논문집
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• 제18권3호
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• pp.555-564
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• 1994

This study has been made to investigate the stress distribution around defects and inclusions that behave as stress concentrators. The stress distribution and interation effects around defects and inclusions was analyzed using Finite Element Method. The results are as follows;(1) Maximum stress point in case of $E_I/E_M>1$($E_I$:elasticity modulus forthe inclusion, $E_M$/:elasticity modulus for the base material)is the vertical point with respect to force direction and in case of $E_I/E_M<1$ it is the parallel point along the hole edge. (2) Interaction effects of ${\sigma}_y$ for the inclusion side is larger than the defect side when the interval between inclusion and defect is near. (3) stress interation effects is large if the difference of ${\sigma}_y$ is small and it is small if the difference of ${\sigma}_y$ is large for the case that the interval between inclusion and defect whose size and property are different is near.

• 한국농업기계학회:학술대회논문집
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• 한국농업기계학회 1996년도 International Conference on Agricultural Machinery Engineering Proceedings
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• pp.852-862
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• 1996

This study was carried out to develop tools to detect defects of apple using machine vision. For the purpose, 6 kinds of frame for color images, R, G, B, h, S, and I frame, and a frame for near infra-red images (NIR frame) were tested first to select one which is useful to segment defect areas from apple images. After then, several methods to classify kind of defect for the segmented defect areas were developed and tested. Five kinds of apple defect -bruise , decay ,fleck worm hole and scar were investigated . The results are as follows: NIR frame was selected as the best one among the 7 kinds of image frame, and R, G and I frames showed favourable result to segment areas of apple defect. Various features of the segmented defect areas were measured to classify the defect areas. Eight kids of feature of the areas-size, roundness, axes length ratio, mean and variance of pixel values, variance of real part of spectrum, mean and variance of power spectrum resulted from spacial ourier transform were observed for the segmented defect areas in the selected 4 frames. then procedures to classify defects using the features were developed for the 4 frames and tested with 75-113 defects on apples. The test resulted that NIR and I frames showed high accuracies to classify the kind of defect as 77% and 76% , respectively.

• 한국자동차공학회논문집
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• 제7권5호
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• pp.221-229
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• 1999

We examined the governing factors of fatigue limit in annealed and austempered ductile iron specimens machined micro hole(dia.<0.4mm) in rotary bending fatigue test. Also, the quantitative relationship between fatigue limit and maximum defect size in specimens was investigated. Artificial defect(micro-pit type, dia.<0.4mm) on specimen surface did not bring about an obvious reduction of fatigue limit in austempered ductile iton(ADI) as compared with annealed ductile iron. According to the investigation of ${\sqrt{area}}_c$ which is the critical defect size to crack initiation at artificial defect, ${\sqrt{area}}_c$ of ADI was larger than that of annealed ductile iron. This shows that the situation of crack initiation at artificial defect in ADI is more difficult in comparison with annealed ductile iron. Maximum defect size is one of the important parameters to predict fatigue limit. And, the quantitative relationship, between the fatigue limit ${\sigma}_{\omega}$ and the maximum defect size ${\sqrt{area}}_{max}$ can be expressed to ${\sigma}_{\omega}^n{\cdot}{\sqrt{area}}_{max}=C_2$ where, $C_2$ are constant. Moreover, it is possible to explain the difference in fatigue limit between, austempered and annealed ductile iron by introducing the parameter ${\delta}(=N_{sg}/N_{total})$in a plain spectimen.

• Journal of Mechanical Science and Technology
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• 제14권10호
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• pp.1021-1027
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• 2000

In this study, fatigue tests were performed to examine the effects of micro drill hole on fatigue limit of as cast and austempered ductile cast iron (ADI) using the rotary bending fatigue tester. As results, micro drill holes ($diameter{\leq}0.4mm$) did not influence the fatigue limit of ADI, compared to annealed ductile cast iron; the critical defect size of crack initiation, in ADI was larger than as cast. If the ${\sqrt{area}}$ of micro drill hole and graphite nodule in ADI are comparable, crack initiates at the graphite nodule. When the ruggedness developes through austempering treatment process, microstructure on crack initiation at micro drill hole is tougher than that of as cast ductile cast iron.

• 한국소음진동공학회논문집
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• 제13권6호
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• pp.423-429
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• 2003

On this study. we improved the efficiency applying algorithm that is repeatedly using table of orthogonal array in discrete design space and filling a defect of gradient method in continuous design space. we showed optimal ply angle that maximized 1st natural frequency of CFRP laminated composite plate without a hole and with a hole by each aspect ratio. In the case of CFRP laminated composite plate without a hole, we confirmed the reliance and efficiency of algorithm in comparison with the result of optimization achievement repeatedly using statistical table of orthogonal array of experimental design and the BFGS optimal design method.

• 상하수도학회지
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• 제31권1호
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• pp.21-28
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• 2017

This study was performed to propose the sewer defect scoring, and grading protocols for sewer condition assessment. For this, sewer defect scoring methods were comparatively analyzed and reviewed for four international condition assessment protocols, which are established based on WRc manual. As a result, we proposed a new protocol for sewer condition assessment, in which characteristics of sewer pipes are considered by segment. In reference to the PIM-3, the extent of ground subsidence was adopted to be of importance, and renewal scores increased in accordance with weighting of defects causing structural backfill materials. Also, defect grades of 'Hole' were extended to 5 levels of the grading, and 'Surface Damage' was excluded in defect assessment. The addition of 'Buckling' resulted in reduction of weights in 'Surface Damage' and 'Lining Defects'.

• 한국정밀공학회지
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• 제20권2호
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• pp.146-153
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• 2003

Ultrasonic inspection of defects has been focused on the existence of defect in structural material and need has much time and expenses in inspecting all the coordinates (x, y) on material surface. Neural networks can have an application to coordinates (x, y) of defects by multi-point inspection method. Ultrasonic inspection modeling is optimized by neural networks Neural networks has trained training example of absolute and relative coordinate of defects, and defect pattern. This method can predict coordinates (x, y) of defects within engineering estimated mean error $\psi$.

• Journal of Magnetics
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• 제18권2호
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• pp.81-85
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• 2013

We investigate the electronic and magnetic properties in Cu-doped InN with the N vacancy ($V_N$) from first principles calculations. There is the long-range ferromagnetic order between two Cu atoms, attributed to the hole-mediated double exchange through the strong p-d interaction between the Cu atom and neighboring N atom. The system of $V_N$ defect in Cu-doped InN has the lowest formation energy. Due to the hybridization between the Cu-3d and $V_N$ states, the spin-polarization on the Cu atoms in the InN lattice is reduced by $V_N$ defect. So, it shows a weak ferromagnetic behavior.

• 한국임상수의학회지
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• 제19권1호
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• pp.110-113
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• 2002

An atrial septal defect (ASD) is a congenital hole in the atrial septum that allows flow between the two atria. Small ASDs are usually well-tolerated defects and do not result in significant clinical abnormalities. In large ASDs or in the presence of other cardiac defects, clinically significancy is increased. Atrial septal defects in 2 Dogs with cardiac and respiratory signs were diagnosed at seoul animal medical center. In ascultation, systolic murmur and the splitting of second heart sound were heard at pulmonary or tricuspid valve region. In radiograph, right-sided cardiomegaly, pulmonary artery dilation, increased pulmonary vasculature makings, and pleural effusion or pulmonary edema signs were observed. In echocardiography, the region, location and size of septal defect was identified. Also, the direction and degree of shunt was measured. These dogs were treated with medicine for cardiac failure. One dog is well-tolerated, the other dog died.

• 마이크로전자및패키징학회지
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• 제13권4호
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• pp.45-50
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• 2006

3D package의 SiP에서 구리의 via filling은 매우 중요한 사항으로 package밀도가 높아짐에 따라 via의 크기가 줄어들며 전기도금법을 이용한 via filling이 연구되어왔다. Via filling시 via 내부에 결함이 발생하기 쉬운데 전해액 내에 억제제, 가속제등 첨가제를 첨가하고 펄스-역펄스(PRC)의 전류파형을 인가하여 결함이 없는 via의 filling이 가능하다. 본 연구에서는 건식 식각 방법 중 하나인 DRIE법을 이용하여 깊이 $100{\sim}190\;{\mu}m$, 직경이 각각 $50{\mu}m,\;20{\mu}m$인 2가지 형태의 via을 형성하였다. DRIE로 via가 형성된 Si wafer위에 IMP System으로 Cu의 Si으로 확산을 막기 위한 Ta층과 전해도금의 씨앗층인 Cu층을 형성하였다. Via시편은 직류, 펄스-역펄스의 전류 파형과 억제제, 가속제, 억제제의 첨가제를 모두 사용하여 filling을 시도하였고, 공정 후 via의 단면을 경면 가공하여 SEM으로 관찰하였다.