• Journal of the Semiconductor & Display Technology
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• v.10 no.2
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• pp.7-12
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• 2011

In this paper, a laser scattering mechanism are designed to detect micro defects such as dent, scratch, pinhole, etc. Its influential parameters are experimentally selected and scattering patterns of micro defects have been analyzed for silicon wafer in solar cell. As a result of experiments, scattered lights are rather increased in wafer surface with micro defects, in comparison to no micro ones. Scattering parameters are optimally selected for obtaining robust and high quality laser scattering images of micro defects. It is shown that scattered light components are linearly increased according to the increase of micro defect sizes, and the depth of micro-defects give a large influence on optical deflection.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2007.11a
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• pp.203-204
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• 2007

This paper investigated the influence on partial discharge distribution of various defects at the model power cable joints interface using K-means clustering. As the result of analyzing discharge number distribution of ${\Phi}-n$ cluster, clusters shifted to $0^{\circ}\;and\;180^{\circ}$ with increasing applying voltage. It was confirmed that discharge quantity and euclidean distance between centroids were increased with applying voltage from the analyzing centroid distribution of ${\Phi}-q$ cluster. The degree of dispersion was increased with calculating standard deviation of ${\Phi}-q$ cluster centroid. The tendency both number of discharge and mean value of ${\Phi}-q$ cluster centroid were some different with defect types.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.25 no.6
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• pp.849-852
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• 2021

This paper presents a vision based tire mold inspection system where mold defects are inspected and the sizes of specific parts of the mold are measured. There are a lot of challenging issues as letters and pictures of intaglio are engraved on a bright surface of the tire mold. To solve the issues, we carefully selected a line-scan camera and a line light. In addition, we used PLC to control the mechanical parts. The developed system provides inspection of misspelled and deformed letters as well as a variety of the functions such as size measurement of engraved regions and inspection report file creation.

• Journal of Ocean Engineering and Technology
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• v.27 no.3
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• pp.61-66
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• 2013

This paper presents the results of finite element simulations of elastic wave propagation in an underwater steel plate and the verification of a proposed method utilizing elastic wave-based damage detection. For the simulation and verification, we carried out the following procedures. First, three-dimensional finite element models were constructed using a general purpose finite element program. Second, two types of damages (mechanical defects and deteriorations) were applied to the underwater steel plate and three parameters (defect location, defect width, and depth) were considered to adjust the severity of the applied damages. Third, elastic waves were generated using the oblique incident method with a Gaussian tone burst, and the response signals were obtained at the receiving point for each defect or deterioration case. In addition, the received time domain signals were analyzed, particularly by measuring the magnitudes of the maximum amplitudes. Finally, the presence and severity of each type of damage were identified by the decreasing ratios of the maximum amplitudes. The results showed that the received signals for the models had the same global pattern with minor changes in the amplitudes and phases, and the decreasing ratio generally increased as the damage area increased. In addition, we found that the defect depth was more critical than the width in the decrease of the amplitude. This mainly occurred because the layout of the depth interfered with the elastic wave propagation in a more severe manner than the layout of the width. An inverse analysis showed that the proposed method is applicable for detecting mechanical defects and quantifying their severity.

• Journal of the Korean Society of Environmental Restoration Technology
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• v.23 no.3
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• pp.91-104
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• 2020

This study was conducted to analyze the characteristics of defects according to the type of block and spatial type by quantitatively examining defects occurring in block pavement in apartment complex. According to the research results, depending on the type of block, defects have occurred 1,394.3ea/100㎡ in interlocking paver blocks, 464.8ea/100㎡ in clay brick paver blocks, and 235.1ea/100㎡ in shot blasted paver blocks. By space type, the defects were occurred 1,576.0ea/100㎡ on the access road paved by interlocking paver blocks and the defects were found 1,139.6ea/100㎡ in interlocking paver blocks, 235.1ea/100㎡ in shot blasted paver blocks, and 797.1ea/100㎡ in clay brick paver blocks, on the sidewalk. Also the defects are occurred 455.6ea/100㎡ on the resting space and 403.2ea/100㎡ on the gym space paved by clay brick paver blocks. Through the size analysis of the defects in the block paver, in the case 'peeling', the largest volume of 2,539.0㎣ on the sidewalk paved with shot blasted paver blocks, and 'Subsidence' occurred at the widest area of 2,096.0㎠ on the sidewalk where interlocking paver block was constructed. The difference in defect occurrence according to the type of block is considered to be influenced by the block production process, and the space type is considered to be caused the difference in the occurrence of defects according to the cause of construction and the usage pattern of residents. This study conducted a survey on defects in block and analyzed the defect characteristic according to paver material and space type. Base on this, it is judged that it can be used as an efficient basic data for material replacement, improvement, paver planning and construction in the future.

• Archives of Plastic Surgery
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• v.33 no.6
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• pp.748-752
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• 2006

Purpose:Circular skin lesions between 10 and 35 mm in diameter generate problems often. Direct closure of the lesion risks excessive wound tension or wound dehiscence. Skin grafts heal slowly and often remain unsightly. Traditional skin flaps have a limited role. We treated this circular medium-sized skin lesion(10 - 35 mm sized) by reducing opposed multilobed(ROM) flap. Methods: ROM flap involves a series of semicircular lobes extending both cephalic and caudal from the defect. Direction of the semicircular multilobed flap is set parallel to relaxed skin tension line(RSTL) to minimize scar formation. First semicircle is drawn 60% in diameter of the defect. Second semicircles are drawn at the cephalic and caudal aspects of the original semicircles. These semicircles are 60% in diameter of the first semicircle. Additional semicircles are repeatedly drawn until the tension of skin flaps becomes free. ROM flap has a length-to-base ratio of 0.5 resulting in lower theoretical risk of end flap necrosis than a random pattern flap with a large ratio. The technique involves lobes most distant from the primary defect being transposed in turn closer to the defect. Results: The ROM flap reduces skin tension concerns, lowers the risk of flap necrosis and allows for quicker and more aesthetic healing. Results were generally good and major complications, such as dehiscence, infection, or delayed healing, did not occur. Conclusion: ROM flap repair allows the plastic surgeon an additional option when faced with a circular medium-sized skin lesion.

• Korean Journal of Construction Engineering and Management
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• v.16 no.2
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• pp.21-28
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• 2015

Construction defects are major components that result in cost overruns and schedule delays in construction projects. There have been extensive research efforts to investigate the cause of defects. However, little effort has been devoted to analyze correlation among various reasons of construction defects while a defect is not usually an outcome of a single cause, but rather occurs when several interrelated causes combine. Based on this recognition, this paper analyzes 831 nonconformity reports collected from 30 construction projects in Korea from 2011 to 2014. The correlation analysis revealed that a significant portion of construction defects occurred in the procurement and construction phase and as the pattern of function defect and installation defect. Triggered by human error, defective material and faulty method, these defects are treated by conccession, repair, rework that can significantly lower the cost and schedule performance. This paper is significant in terms of providing a theoretical basis for analyzing correlation among various reasons of construction defects and quantitative measures for establishing effective defect prevention strategies.

• The Transactions of the Korean Institute of Electrical Engineers
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• v.40 no.8
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• pp.731-740
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• 1991

This paper presents a knowledge based system to solve reactive power/voltage control problem in a power system. The methods to reduce inference time are proposed in inferring the solution of problem in the knowledge base which consists of heuristic rules and inowledge of experts. A set of indices drawn from the heuristic knowledge on the power system is utilized to make up for the defect of existing knowledge based systems which determine both the location and the amount of reactive power compensation devices. The concept of set of indices developed in this paper makes it possible to infer the amount of reactive power source only since the bus order list representing priority for the location of reactive power compensator to be switched on can be determined in advance. From the fact that there exists a relationship between the system voltage pattern and the reactive power pattern in operation, the pattern recognition technique is introduced to reduce the inference time in solving the severe voltage problem. To demonstrate the usefulness of the proposed knowledge based system, the IEEE 30 bus system is chosen as a sample system. The results of case study are also presented.

• The Journal of the Korea institute of electronic communication sciences
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• v.11 no.5
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• pp.465-472
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• 2016

This study materialized an FPGA-based system to extract PCB patterns. The Printed Circuit Boards that are produced these days are becoming more detailed and complex. Therefore, the importance of a vision system to extract defects of detailed patterns is increasing. This study produced an FPGA-based system that has high speed handling for vision automation of the PCB production process. A vision library that is used to extract defect patterns was also materialized in IPs to optimize the system. The IPs materialized are Camera Link IP, pattern matching IP, VGA IP, edge extraction IP, and memory IP.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.57 no.12
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• pp.2313-2321
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• 2008

In order to develop reliable on-site partial discharge(PD) pattern recognition algorithm, the fuzzy neural network based on fuzzy set(FNN) and the polynomial network pattern classifier based on fuzzy Inference(PNC) were investigated and designed. Using PD data measured from laboratory defect models, these algorithms were learned and tested. Considering on-site situation where it is not easy to obtain voltage phases in PRPDA(Phase Resolved Partial Discharge Analysis), the measured PD data were artificially changed with shifted voltage phases for the test of the proposed algorithms. As input vectors of the algorithms, PRPD data themselves were adopted instead of using statistical parameters such as skewness and kurtotis, to improve uncertainty of statistical parameters, even though the number of input vectors were considerably increased. Also, results of the proposed neuro-fuzzy algorithms were compared with that of conventional BP-NN(Back Propagation Neural Networks) algorithm using the same data. The FNN and PNC algorithms proposed in this study were appeared to have better performance than BP-NN algorithm.