• Journal of the Korean Institute of Telematics and Electronics S
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• v.35S no.4
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• pp.76-84
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• 1998

The requirements of the accuracy, the high speed and the stability are very important factors in the defect-detection sytem for the texture. In this paper, we describe a novel scheme of the defect detection using a statistical behavior of defect patterns. Some prior knowledge as to the characteristics of flaws is that the defects are consistently distributed in the space and the noise are randomly generated. An empirical knowledge is adapted for the binarization and the determination process of defects in textured image. Since the process of the determination exclude the segmentations or delineation steps, we are able to meet the speed requirements. We show the validity of the scheme through the simulation of textured images.

• Computers and Concrete
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• v.7 no.1
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• pp.63-81
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• 2010

We present the shape determination method of 3-D reinforcement corrosion based on observed temperature on concrete surface. The non-destructive testing for reinforcement corrosion in concrete using a heat image on concrete surface have been proposed by Oshita. The position of the reinforcement of corrosion or the cavity can be found using that method. However, the size of those defects can not be precisely measured based on the heat image. We therefore proposed the numerical determination system of the shape for the reinforcement corrosion using the observed temperature on the concrete surface. The adjoint variable method is introduced to formulate the shape determination problem, and the finite element method is employed to simulate the heat transfer problem. Some numerical experiments and the examination for the number of the observation points are shown in this paper.

• Korean Journal of Construction Engineering and Management
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• v.23 no.5
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• pp.23-33
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• 2022

Cracks, which account for the largest proportion of defect lawsuits in apartment buildings, are not clear on the criteria for defect determination, so judgments about defects are mixed. Interlayer cracks, which account for most of the crack defect judgment amount, tend to be judged as defects regardless of the crack width or condition, and repair methods are mostly set uniformly. This starts from the problem that the standards of the Ministry of Land, Infrastructure and Transport and the Construction Appraisal Practice, which the courts use as standards, do not match. It is necessary to establish a defect determination standard that can be applied to all stakeholders through the amendment of laws and the revision of the Court Appraisal Practice. In addition, it is necessary to apply the crack repair method according to the width and condition of the interlayer crack. If the defect determination and the application of the repair method for cracks are rationalized, it could serve as an opportunity to change the current trend of defect disputes that rely only on litigation.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 1999.03b
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• pp.161-164
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• 1999

In order to investigate the effect of punching condition on the stretch flange formability of sheet for deep drawing hole expansion tests at various edge condition were done. Edge conditions were changed by altering tool clearances artifical defects grinding and deburring. For a determination of optimum edge condition of side panel of automobile punched section analysis and forming results were studied and the laboratory test results were used. In case of considered side panel tool clearance should be less than 15% and punched edge should be uniform without defects for safe forming

• Proceedings of the KSME Conference
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• 2008.11a
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• pp.305-310
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• 2008

This paper provides the methods to estimate the burst pressures of the pipes with defects, based on finite element analyses. FE codes are frequently adopted for the simulations of the burst tests of the pipes with defects. However, those do not give the burst pressure directly. Because the post-processing should be followed; determination of the fracture strains in accordance with triaxialities, monitoring the strains of pipes, etc. In the present work, these efforts are implemented in the user subroutine UHARD within the general-purpose FE code, ABAQUS. Four fracture criterions are introduced to estimate the burst pressure of pipes, and a simple fracture strain estimate is also developed. FE analyses for the pipe with gouge and corrosion are performed, and the results are compared with the experiment results.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2003.05a
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• pp.216-220
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• 2003

Most important for meaningful forging simulation is the determination of correct process parameters. In addition a check and a compensation of the data base after the comparison between experiments and the computation of the developed process is necessary. The existence of a systematic process parameter data bank for special kinds of forming process in combination with forging specific simulation lifts the value of the products. Finite volume method is applied to simulate the hot forging process to investigate the defects for the automobile product. Three typical forging processes have been investigated; Extrusion by hydrolic press, Upsetting by crank press and Inclined upsetting by hammer press. Simulated result has compared with the experiment and provided a direction to improve the process.

• Composites Research
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• v.17 no.1
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• pp.1-9
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• 2004

A new non-destructive evaluation method using tapping sound is proposed. This method, named Tapping Sound Analysis, is using the difference between tapping sound data of healthy structure and defective structure as the criteria of determination of internal defect of composite structure. For the characterization of tapping sound, a feature extraction method based on wavelet packet transform is proposed. And a feature index is defined for the decision of existence of internal defects. To prove the possibility of proposed method as a non-destructive evaluation method, experimental study is performed. The tapping sound data of healthy structure and defective structure are measured and compared based on the proposed decision method. The experimental results showed that the feature index is a good indicator for the determination of internal defects.

• International Journal of Fuzzy Logic and Intelligent Systems
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• v.2 no.1
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• pp.89-93
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• 2002

This paper introduces a vision-based on-line fabric inspection methodology of woven textile fabrics. Current procedure for determination of fabric defects in the textile industry is performed by human in the off-line stage. The advantage of the on-line inspection system is not only defect detection and identification, but also 벼ality improvement by a feedback control loop to adjust set-points. The proposed inspection system consists of hardware and software components. The hardware components consist of CCD array cameras, a frame grabber and appropriate illumination. The software routines capitalize upon vertical and horizontal scanning algorithms characteristic of a particular deflect. The signal to noise ratio (SNR) calculation based on the results of the wavelet transform is performed to measure any deflects. The defect declaration is carried out employing SNR and scanning methods. Test results from different types of defect and different style of fabric demonstrate the effectiveness of the proposed inspection system.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2015.05a
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• pp.245-246
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• 2015

Cases of lawsuit and conflict are increasing because of defects in apartments in use after the completion of construction. Further, with changes in the consciousness of residents and in the social environment, many residents are showing interest in defect-related lawsuits. However, the term of warranty liability defined in the current law is not practically appropriate, and the verification of the determination of the term of warranty liability is insufficient. Against this background, this research aims to evaluate the appropriateness of defect repair periods by examining the actual defect condition of the finishing work among the various defects related to apartments. Collected performance data are analyzed by statistical techniques by considering the defect occurrence rate per construction type and the construction year of the finishing work in apartment construction. The analysis results will be used as basic data for evaluating the appropriateness of the standards for the term finishing works warranty liability.

• Journal of Practical Engineering Education
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• v.15 no.2
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• pp.419-427
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• 2023

In this study, optimal adhesion conditions to alleviate defects caused by heat shrinkage with FDM type 3D printers with machine learning are researched. Machine learning is one of the "statistical methods of extracting the law from data" and can be classified as supervised learning, unsupervised learning and reinforcement learning. Among them, a function model for adhesion between the bed and the output is presented using supervised learning specialized for optimization, which can be expected to reduce output defects with FDM type 3D printers by deriving conditions for optimum adhesion between the bed and the output. Machine learning codes prepared using Python generate a function model that predicts the effect of operating variables on adhesion using data obtained through adhesion testing. The adhesion prediction data and verification data have been shown to be very consistent, and the potential of this method is explained by conclusions.