• Journal of the Korean Institute of Intelligent Systems
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• v.10 no.2
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• pp.75-82
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• 2000

This paper presents a method of detecting surface flaw of cold-rolled steel plate using image processing technique and a neural network classifier. The amount of steel plate surface image data is reduced by the wavelet transform. Features are extracted from the co-occurence matrix of the partial image corresponding to the low-frequency region, and a MLP neural network classifies into predetermined surface flaw categories. Simulations show the neural network classifier outperforms conventional vector quantization method.

• Wind and Structures
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• v.21 no.6
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• pp.709-726
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• 2015

In this study, a novel vision-based bolt-loosening monitoring technique is proposed for bolted joints connecting tubular steel segments of the wind turbine tower (WTT) structure. Firstly, a bolt-loosening detection algorithm based on image processing techniques is developed. The algorithm consists of five steps: image acquisition, segmentation of each nut, line detection of each nut, nut angle estimation, and bolt-loosening detection. Secondly, experimental tests are conducted on a lab-scale bolted joint model under various bolt-loosening scenarios. The bolted joint model, which is consisted of a ring flange and 32 sets of bolt and nut, is used for simulating the real bolted joint connecting steel tower segments in the WTT. Finally, the feasibility of the proposed vision-based technique is evaluated by bolt-loosening monitoring in the lab-scale bolted joint model.

• Journal of Welding and Joining
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• v.19 no.4
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• pp.379-383
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• 2001

Resistance spot welding has been widely used in the sheet metal joining processes because of low cost, high productivity and convenience. Recently, automobile and aerospace industries are trying to replace partly steel sheets with aluminum alloy sheets. But in the case of dissimilar materials, to apply resistance spot welding has been known to be very difficult owing to the effect of melting temperature. On this study, an effort was made to apply spot welding of dissimilar sheet metals, 2024 aluminum alloy and zinc coated steel sheet, evaluate the spot weld quality with tensile-shear strength test and nondestructive evaluation technique, C-scan image methodology. In this study results, as the current below 11 kA, melting of materials is not achieved well. Also as the current exceeds to 13.5 kA, the more spatters happen at welded zone and tensile-shear strength lowered. So, the feasibility of C-scan image technique proposed in the study is found to be suitable evaluation method for resistance spot weldability.

• The Journal of the Korea institute of electronic communication sciences
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• v.7 no.5
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• pp.1033-1039
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• 2012

In this paper, a simple and robust algorithm is proposed for detecting each steel plate from a image which contains several steel plates. Steel plate is characterized by line edge, so line detection is a fundamental task for analyzing and understanding of steel plate images. To detect the line edge, the proposed algorithm uses the small eigenvalue analysis. The proposed approach scans an input edge image from the top left corner to the bottom right corner with a moving mask. A covariance matrix of a set of edge pixels over a connected region within the mask is determined and then the statistical and geometrical properties of the small eigenvalue of the matrix are explored for the purpose of straight line detection. Using the detected line edges, each plate is determined based on the directional information and the distance information of the line edges. The results of the experiments emphasize that the proposed algorithm detects each steel plate from a image effectively.

• Journal of the Korean institute of surface engineering
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• v.54 no.2
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• pp.84-89
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• 2021

The visual inspection method is widely used for corrosion damage analysis of steel plate due to the cost-efficient, fast and reasonably accurate results. However, visual inspection of corrosion deteriorated degree has a problem that the reliability of results differs depending on the inspector's individual knowledge and experience. In this study, we evaluated the degree of corrosion from a given image by using image segmentation method based on the grabcut and HSV(Hue, Saturation, Value) color image processing techniques for the development of an automatic inspection tool. The code written in Python based OpenCV-python libraries was used to categorize the images.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.15 no.7
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• pp.1479-1486
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• 2011

In this paper, a simple and robust algorithm is proposed for detecting straight line segments in a steel plate image. Line detection from a steel plate image is a fundamental task for analyzing and understanding of the image. The proposed algorithm is based on small eigenvalue analysis. The proposed approach scans an input edge image from the top left comer to the bottom right comer with a moving mask. A covariance matrix of a set of edge pixels over a connected region within the mask is determined and then the statistical and geometrical properties of the small eigenvalue of the matrix are explored for the purpose of straight line detection. Before calculating the eigenvalue, each line segment is separated from the edge image where several line segments are overlapped to increase the accuracy of the line detection. Additionally, unnecessary line segments are eliminated by the number of pixels and the directional information of the detected line edges. The respects of the experiments emphasize that the proposed algorithm outperforms the existing algorithm which uses small eigenvalue analysis.

• Journal of the Semiconductor & Display Technology
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• v.12 no.1
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• pp.15-21
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• 2013

In this paper, sensor system and inspection algorithm in order to inspect steel balance weight for automobile is described. Steel balance weight is composed of clip and weight, which is joined by press process. The defective one has a gap between clip and weight. To detect whether there is a gap, sensor system is simply configured with laser line projector and USB camera, which make it possible to measure the height difference of clip and weight area. Laser line pattern which is made on the surface of a balance weight is captured by USB camera. In case that USB camera is used in machine vision, barrel distortion caused by wide angle lens makes the captured image distorted. Image warping function is applied to correct the distortion. Simple image processing algorithm is applied to extract the laser line information and whether it is good or not is judged through the extracted information.

• The Journal of Korean Institute of Information Technology
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• v.17 no.8
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• pp.75-83
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• 2019

In this paper, we propose a method that can detect and trace the end point of real - time reinforcement steel to various environmental conditions of industrial field by using Median flow and Depth information. We proposed a method to derive two steel end points by using Median filter, Binarization, Morphology, and Blob algorithm on image depth information. The coordinates of the final position were determined by comparing the coordinates of the reinforcement steel endpoints detected in the Depth image and the position tracking coordinates of the reinforcement steel using Median Flow. As a result, when the existing Median Flow method was used, the success rate of the final position determination of reinforcement steel of 75% was increased to 95% when the Depth of reinforcement steel was used.

• Structural Engineering and Mechanics
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• v.77 no.5
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• pp.637-650
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• 2021

The paper presents an investigation of the widely varying mechanical performance and behaviour of steel and Glass Fibre Reinforced Polymer (GFRP) reinforced concrete beams using non-destructive techniques of Acoustic Emission (AE) and Digital Image Correlation (DIC) under four-point bending. Laboratory experiments are performed on both differently reinforced concrete beams with 0.33%, 0.52% and 1.11% of tension reinforcement against balanced section. The results show that the ultimate load-carrying capacity increases with an increase in tensile reinforcement in both cases. In addition to that, AE waveform parameters of amplitude and number of AE hits successfully correlates and picks up the divergent mechanism of cracking initiation and progression of failure in steel reinforced and GFRP reinforced concrete beams. AE activity is about 20-30% more in GFRP-RC beams as compared to steel-RC beams. It was primarily due to the lower modulus of elasticity of GFRP bars leading to much larger ductility and deflections as compared to steel-RC beams. Furthermore, AE XY event plots and longitudinal strain profiles using DIC gives an online and real-time visual display of progressive AE activity and strains respectively to efficaciously depict the crack evolution and their advancement in steel-RC and GFRP-RC beams which show a close matching with the micro-and macro-cracks visually observed in the actual beams at various stages of loading.

• Journal of the Korean Institute of Intelligent Systems
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• v.19 no.2
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• pp.153-159
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• 2009

The steel balls are core elements between inner part and outer part in a bearing system. The degree of goodness of the steel balls has been visually processed by human beings. In this paper we propose a new method that uses image processing algorithm and fuzzy logic theory. We use fuzzy inference engine and fuzzy Choquet integral algorithm in the proposed system. We first distinguish the defects of the steel balls by an image processing algorithm. And then the degree of the defects is classified by a fuzzy logic system. We perform some simulations to show the effectiveness and feasibility of the proposed system.