• Journal of the Korea institute for structural maintenance and inspection
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• v.24 no.3
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• pp.1-8
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• 2020

Recent the number, size and accident on Youth Training Facility have increased annually. Also, the discussion and interest relation to safety and maintenance of youth culture and education. This study asserts the necessity and importance of present condition and characteristic based on Youth Training Facility in domestic. Therefore, Results of this study, it is appeared that very vulnerable to improve safety and maintenance in them. Accordingly, The purpose of this study is to investigate the current status for the whole youth facilities. second it estimate on main damage and defect of them for the period four years.

• Journal of Institute of Convergence Technology
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• v.6 no.1
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• pp.23-26
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• 2016

DC motor shafts have several defects such as double cut, deep scratch on surface, and defects in diameter and length. The deep scratches are due to collision among the other shafts. So the scratches are long and thin but their orientations are random. If the smallest enclosing box, i.e. oriented bounding box for a detective point group is found, then the size of the corresponding defect can be modeled as its diagonal length. This paper proposes an suface inspection algorithm for the DC motor shaft using the oriented bounding box. To evaluate the proposed algorithm, a test bed is made with a line scan CCD camera (4096 pixels/line) and two rollers mechanism to rotate the shaft. The experimental result on a pre-processed image with contrast streching algorithm, shows that the proposed algorithm sucessfully finds 150 surface defects and its computation time (0.291 msec) is enough fast for the requirement (4 seconds).

• Journal of Sensor Science and Technology
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• v.33 no.3
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• pp.179-184
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• 2024

In the car industry, welding is a fundamental linking technique used for joining components, such as steel, molds, and automobile parts. However, accurate inspection is required to test the reliability of the welding components. In this study, we investigate the detection of weld beads using 2D image processing in an automatic recognition system. The sample image is obtained using a 2D vision camera embedded in a lighting system, from where a portion of the bead is successfully extracted after image processing. In this process, the soot removal algorithm plays an important role in accurate weld bead detection, and adopts adaptive local gamma correction and gray color coordinates. Using this automatic recognition system, geometric parameters of the weld bead, such as its length, width, angle, and defect size can also be defined. Finally, on comparing the obtained data with the industrial standards, we can determine whether the weld bead is at an acceptable level or not.

• Journal of the Korean Society of Industry Convergence
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• v.26 no.5
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• pp.725-731
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• 2023

In this study, the harmless crack size was evaluated using carburized, quenched-tempered SCM822H steel. The possibility of detecting cracks that reduce the fatigue limit by non-destructive inspection was evaluated. The conclusions obtained are as follows. The retained austenite of surface was reduced by SP. About 35% and 65% of the retained austenite on the surface were transformed into strain-induced martensite, increasing the hardness by 79HV and 122HV over the as-received material. The maximum compressive residual stresses introduced on the surfaces were -695 MPa and -688 MPa, respectively. The fatigue limit increased by 1.48 times and 1.67 times, respectively, compared to the as-received material. The harmless crack size of SP specimen was determined differently depending on the shot ball size.

• Journal of the Korean Society for Nondestructive Testing
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• v.23 no.6
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• pp.594-604
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• 2003

A State-of-art methodologies on implementing conventional piezoelectric and flexible PVDF elements for generating ultrasonic guided waves in a tubing are presented. Comb transducers with PVDF can be efficiently applied to selectively excite a guided wave mode by wrapping around any size pipe while a conventional immersion type piezo-elements can be also possibly used with a modification of transducer fabrication. Technical comparisons between the use of angle beam probe and comb one will be also discussed in detail. The presented technique can be easily applied to NDE for a long range inspection of tubular structures.

• The Transactions of the Korea Information Processing Society
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• v.7 no.6
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• pp.1973-1979
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• 2000

Driving the need for machine vision system is growing consumer demand for quality and defect-free products. Especially it is the most important in tarpaulin's manufacturing process achieves automatically by machine vision instead of by man vision. In this paper pinholes detection is performed by using morphology algorithms. Top hat transform is one of morphology applications. This transform take high performance of defect detection in the case that unexpected changes occur in some non-uniform background. For pinholes defect, automatic visual inspection system has been developed, which was composed by a line-scan camera, illumination, a frame grabber, a motor driver and control units. This system has excellent capacity to defect pinholes to the 0.1 mm by 0.5 mm in size and to work in moving objects by maximum 20 m/min in speed.

• Magazine of the Korean Society of Agricultural Engineers
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• v.44 no.3
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• pp.101-110
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• 2002

Most of the agricultural structures are in shortage of feasible facility management because these structures are small in size and spacially distributed in rural area. Inspection tools based on visual inspections are generally used for agricultural structures in most of the countries, including Korea. It is necessary to survey data of the irrigation structures to maintain records, and to develop the interface program by constructing database of inspection data. This study was conducted to develop a system for safe appraisal and repair works on agricultural irrigation structures. Repair and rehabilitation method can be chosen from an optimum viewpoint if the information between the method and life-cycle management cost of agricultural structures is constructed in the database. In this study, the system assisting onsite field investigation and determining the typical rehabilitation method of typical agricultural structural problems such as fractures and cracks of members was developed.

• Journal of Welding and Joining
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• v.20 no.2
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• pp.65-70
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• 2002

This study was to evaluate GMA welding characteristics of the A15083-O aluminum alloy according to the shield gas mixing ratio and heat input change. The GMA welding of the base metal was carried out with flour different shield gas mixing ratios(Ar100%+He0%, Ar67%+He33%, Ar50%+He50%, and Ar33%+He67%). Regarding the if1uence on the bead shape of the shield gas mixing ratio and heat input, the bead width was greatest in Ar100%+He0% mixture. But the penetration depth and area were greatest in Ar33%+He67% mixture considering that the lower Ax gas ratio, the higher bead depth and area. Also, dilution was also best in the shield gas mixing ratio. The size and number of deflects were least in Ar33%+He67% mixture. Higher He gas ratio resulted in less deflects detected by the radiographic inspection.

• 제어로봇시스템학회:학술대회논문집
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• 1996.10b
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• pp.1024-1027
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• 1996

The cyclic production lines have the first machines starved and the last machine blocked due to the lack or the excess of empty pallets in the feedback buffer. A workpiece in the cyclic production lines is transported on a pallet, and the total sum of pallets in the system does not changed during the system operation time. Therefore, the production rate of the cyclic production lines are dependent on the total number of pallets in the system. In this paper, we suggest the performance analysis method for the cyclic production lines with inspection machines and the optimal total number of pallets in the system that maximizes the production rate of the system. Finally, we validate the suggested methods by simulations.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1996.04a
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• pp.271-275
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• 1996

In this paper, an automatic spot inspection system has been developed for camera target lens using the computer aided vision system. The developed system comprises: light source, magnifying optics, vision camera, XY robot, and a PC. An efficient algotithm for the spot detection has been implemented, thus up tof ew micrometer size spots can be effectively identified in real time. The developed system has been fully interfaced with XY robot systenm, PLCs, thus the practical spot inspection system has been implemented. The system has been applied to a practical camera manufacturing process, and showed its efficiency.