• Smart Structures and Systems
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• v.29 no.1
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• pp.141-151
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• 2022

In recent years, the industry and research communities have focused on developing autonomous crack inspection approaches, which mainly include image acquisition and crack detection. In these approaches, mobile devices such as cameras, drones or smartphones are utilized as sensing platforms to acquire structural images, and the deep learning (DL)-based methods are being developed as important crack detection approaches. However, the process of image acquisition and collection is time-consuming, which delays the inspection. Also, the present mobile devices such as smartphones can be not only a sensing platform but also a computing platform that can be embedded with deep neural networks (DNNs) to conduct on-site crack detection. Due to the limited computing resources of mobile devices, the size of the DNNs should be reduced to improve the computational efficiency. In this study, an architecture called pruned crack recognition network (PCR-Net) was developed for the detection of structural cracks. A dataset containing 11000 images was established based on the raw images from bridge inspections. A pruning method was introduced to reduce the size of the base architecture for the optimization of the model size. Comparative studies were conducted with image processing techniques (IPTs) and other DNNs for the evaluation of the performance of the proposed PCR-Net. Furthermore, a modularly designed framework that integrated the PCR-Net was developed to realize a DL-based crack detection application for smartphones. Finally, on-site crack detection experiments were carried out to validate the performance of the developed system of smartphone-based detection of structural cracks.

• 제어로봇시스템학회:학술대회논문집
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• 1997.10a
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• pp.237-240
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• 1997

The design of underwater inspection robot system is presented. This robot system is designed for wall inspection in the nuclear plant facility. This paper describes the major components of the robot and its structures. This robot system is consisted of three parts : mechanical electrical and sensing pail. The main problem of designing mechanical part is to select the mechanism of driving. In this system the propeller driving mechanism is selected which can be move the robot continuously. For reducing the size of robot, we designed the CPU and motor controller board. The sensor system is consisted of two parts. One is environment monitoring part and the other is robot localization system.

• Journal of Korean Society for Quality Management
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• v.23 no.1
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• pp.1-14
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• 1995

ISO 3951 (1989) Sampling Procedures and Charts for Inspection by Variables for Percent Nonconforming is an acceptable quality level (AQL) type sampling scheme. Sample size code letters and inspection levels in this International Standard correspond to those given in the ISO 2859 (1989), a standard for sampling plans by attributes. Two acceptance sampling procedures can be used ; tabular and graphical methods. The graphs could be used in less critical applications while the tabular method would be available for those familiar with MIL-STD-414 tables and to confirm the results of the graphs when needed. The sampling procedures of the ISO 3951 are matched to the ISO 2859 to enable us to move between them. Composite OC and ASN curves are given for AQL 2.5% and code letter F.

• Journal of Korean Society for Quality Management
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• v.24 no.3
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• pp.77-93
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• 1996

This paper is concerned with the International Standard ISO 2859-1 (1989), Sampling Plans Indexed by Acceptable Quality Level (AQL) for Lot-by-Lot Inspection, his standard is AQL type sampling scheme, and incorporates switching rules to move among normal, tightened, and reduced inspections. Sample size code letters and inspection levels of ISO 2859-1 are the same as those of other attributes standards MIL-STD-105D, ANSI Z1.4, and KS A 3109. But ISO 2859-1 has more simple switching rules than KS A 3109 has. The sampling procedures of the ISO 2859-1 are matched to the variables international standard ISO 3951 to enable us to move between them. Composite OC and ASN curves are given for AQL 2.5% and code letter F.

• International Journal of Reliability and Applications
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• v.5 no.1
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• pp.37-46
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• 2004

Coil spring of automobile suspension system is very important to safety and dynamics of passenger car and requires a highly advanced quality control during manufacturing processes. Surface cracks on the coil spring rod produced by mechanical machining and heat treatment may cause a severe accident and large cost to the manufacturer. In order to detect surface cracks of the rod, guided wave technique is applied for a fast total volumetric inspection. Pochhammer equation is studied to investigate the dispersion characteristics of the guided wave in the spring rod and optimal wave modes sensitive to the surface crack are selected experimentally to design the experimental arrangement for the generation of guided wave. Rod samples with different size of artificial axial EDM notch on the surface ranging from 50${\mu}{\textrm}{m}$ to 1 mm are examined by guided wave and inspection results discussed.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 2005.05a
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• pp.424-428
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• 2005

This paper shows a non-contact optical method to inspect micron scale parts which will be manufactured in micro-factory system. This inspection system should have some characteristics like a small size, flexibility, and high measuring speed. In the viewpoint of measuring capabilities, it also has resolution under micron scale with measuring range over millimeter scale. Two methods will be presented in this paper, one is Moire and the other is white-light scanning interferometry. Also some experimental results will be presented to show the possibilities of the proposed inspection system.

• Proceedings of the KIEE Conference
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• 2001.07d
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• pp.2449-2451
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• 2001

The purpose of this paper is to develop image inspection system endows an automatic operating and measuring that the moment values are invariant with respect to variable object size and rotation. In this paper, using these moment feature vector with Hu's 7 invariant moment is also given. The characteristics of section which is applied in the mechanics used moment descriptor of invariant moment detection algorithm for image inspection system. Corresponding rates between 94% and 96% have archived for all object tested.

• Journal of the Semiconductor & Display Technology
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• v.9 no.3
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• pp.59-63
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• 2010

This paper proposes computer visual inspection algorithms for various LCD defects which are found in a manufacturing process. Modular vision processing steps are required in order to detect different types of LCD defects. Those key modules include RGB filtering for pixel defects, gray-scale morphological processing and Hough transform for line defects, and adaptive threshold for spot defects. The proposed algorithms can give users detailed information on the type of defects in the LCD panel, the size of defect, and its location. The machine vision inspection system is implemented using C language in an embedded Linux system for a high-speed real-time image processing. Experiment results show that the proposed algorithms are quite successful.

• Journal of the Korean Society for Precision Engineering
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• v.12 no.10
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• pp.121-129
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• 1995

The objective of this research is to develop an effective inspection planning strategy for sculptured surfaces by using 3-dimensional Coordinate Measuring Machine (CMM). First, the CAD/CAM database is generated by using the Bezier surface patch mathod and variable cutter step size approach for design and machining of the workpiece model. Then, optimum measuring point locations are determained based on the mean curvature analysis to obtain more effective inspection results for the given sample numbers. An optimal probe sequence generation method is proposed by implementing the Traveling Salesperson (TSP) algorithm and new guide point selection methods are suggested based on the concepts of the variable distance between the first and second guide points. Finally, simulation study and experimental work show the effectiveness of the proposed strategy.

• Journal of the Korea institute for structural maintenance and inspection
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• v.25 no.1
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• pp.41-50
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• 2021

In this study, the flow path width (Gap Size), which is the flow path of fluid, was selected differently among various factors that determine the Ccontrol Force of MR damper, and the change of Control Force was confirmed accordingly. For this purpose, two MR dampers with a Gap Size of 1.0mm and 1.5mm were fabricated, respectively, and dynamic load experiments were conducted according to changes in applied current and vibration conditions The experimental results showed that the minimum Control Force was 3.2 times higher than 1.5mm in the case of 1.0mm Gap Size, and the maximum Control Force was 2.3 times higher than 1.5mm in the case of 1.0mm Gap Size. In addition, the increased width of the Control Force according to applied current was 34N for Gap Size 1.0mm, and 12.7N for Gap Size 1.5mm. As the gap Size increased, the overall Control Force and the increase in the Control Force by the applied current decreased. Next, the dynamic range, which is a performance evaluation index of the semi-active Control device, was 2.3 on average under 1.0mm condition and 2.8 on average under 1.5mm condition, confirming the possibility of utilization as a semi-active Control device.