• Journal of Korean Tunnelling and Underground Space Association
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• v.25 no.3
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• pp.245-259
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• 2023

The purpose of this paper is to examine the most recent tunnel scanning systems to obtain insights for the development of non-contact mobile inspection system. Tunnel scanning systems are mostly being developed by adapting two main technologies, namely laser scanning and image scanning systems. Laser scanning system has the advantage of accurately recreating the geometric characteristics of tunnel linings from point cloud. On the other hand, image scanning system employs computer vision to effortlessly identify damage, such as fine cracks and leaks on the tunnel lining surface. The analysis suggests that image scanning system is more suitable for detecting damage on tunnel linings. A camera-based tunnel scanning system under development should include components such as lighting, data storage, power supply, and image-capturing controller synchronized with vehicle speed.

• The Journal of the Korea institute of electronic communication sciences
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• v.15 no.3
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• pp.513-520
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• 2020

Recently, the development of a vision inspection system using machine learning has become more active. This study seeks to develop a defect inspection model using machine learning. Defect detection problems for images correspond to classification problems, which are the method of supervised learning in machine learning. In this study, defect detection models are developed based on algorithms that automatically extract features and algorithms that do not extract features. One-dimensional CNN and two-dimensional CNN are used as algorithms for automatic extraction of features, and MLP and SVM are used as algorithms for non-extracting features. A defect detection model is developed based on four models and their accuracy and AUC compare based on AUC. Although image classification is common in the development of models using CNN, high accuracy and AUC is achieved when developing SVM models by converting pixels from images into RGB values in this study.

• IEMEK Journal of Embedded Systems and Applications
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• v.8 no.2
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• pp.111-119
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• 2013

This paper proposes one method on photometric stereo calibration using the constraint on light source directions in which the light sources have the unknown tilt and slant angles but the slant angles are the same. First, the constraint is analyzed based on the equation of linear ambiguity which leads to the conclusion that another constraint should be added to solve the calibration completely. Later, the combination of constraint on light source directions and the constraint that there exists at least six surface patches having known albedos is exploited to resolve the linear ambiguity up to an accurate and close-form solution. The effective performance of the proposed method is demonstrated through experiment results.

• Proceedings of the Korean Institute of Intelligent Systems Conference
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• 2003.09a
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• pp.644-647
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• 2003

This paper describes a neural network based machine vision system designed for inspecting yellow beans in real time. The system consists of a camera. lights, a belt conveyor, air ejectors, and a computer. Beans are conveyed in four lines on a belt and their images are taken by a monochrome line scan camera when they fall down from the belt. Beans are separated easily from their background on images by back-lighting. After analyzing the image, a decision is made by a multilayer artificial neural network (ANN) trained by the error back-propagation (EBP) algorithm. We use the global mean, variance and local change of gray levels of a bean for the input nodes of the network. In an our experiment, the system designed could process about 520kg/hour.

• Proceedings of the Korean Institute of Intelligent Systems Conference
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• 2005.11a
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• pp.463-466
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• 2005

본 논문은 퍼지로직을 이용하여 메탈스텐실의 홀의 정상-불량 판단을 수행한다. 메탈스텐실 은 PCB의 SMD의 패드 위에 납을 도포하기 위해 사용되는 것으로, 레이저를 이용하여 패드모양과 동일하게 홀을 생성한다. 가공 시 발생하는 불량은 레이저 출력의 약화로 홀이 정상적으로 가공되지 않는 것이다. 검사를 위해 비전시스템을 이용하여 메탈스텐실에 대한 카메라이미지를 획득하고, 기준이미지는 메탈스텐실을 제조하기 위해 사용되는 거버 파일을 이용하여 생성한다. 퍼지로직의 입력변수는 각 이미지에서의 검사대상 홀의 위치오차와 크기비율이고, 출력변수는 홀의 정상판단율이다. 홀의 위치와 크기는 두 이미지에 대해 영상처리를 수행하여 계산한다. 퍼지규칙은 작업자의 판단 규칙을 적용하여 작성한다. 4종류의 메탈스텐실에 대해 정상-불량 판단을 위해 고정된 임계치를 사용하였을 경우와 제안된 퍼지로직을 적용한 실험결과에 대해 설명한다.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.5 no.2
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• pp.57-62
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• 1996

Basically, the idea underlying most edge-detection technique is the computation of a local derivative operator used for edge detection in gray level image. This concept can be easily illustrated with the aid of object which shows an image of a simple lilght on a dark background, Using the gray level profile along a horizontal scan line of the image. the first and second derivatives of it were acquired. This study is to develop an automatic measuring system based on the digital image processing which can be applied to the real time measurement of the characteristics of the ultra-thin thickness. The experimental results indicate that the developed automatic inspection can be applied in real situation.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2013.10a
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• pp.860-861
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• 2013

최근 고도의 산업 발전이 진행되면서 생산현장의 IT 기술을 접목한 자동화시스템이 대두되고 있다. 특히 설계 도면과 생산된 부품의 정합여부를 검사하여 제품의 생산 품질을 관리하는 도면정합검사는 기존의 수작업을 대체하고, 신뢰성을 보장할 수 있는 자동화 시스템의 도입이 필수적이다. 이에 본 논문에서는 비전 시스템을 기반으로 생산된 부품의 이미지를 인식/추출하고, 이를 이미지화된 도면과 매칭하여 정합 검사하는 도면정합검사시스템을 설계하였다. 따라서 기존의 수작업을 대체하여 생산의 효율을 높이고, 보다 정확한 검사기록을 관리하여 생산의 신뢰성 향상에 크게 기여할 수 있을 것이다.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2013.10a
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• pp.854-855
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• 2013

최근 국내 전력공급 문제에 따라 다양한 에너지절감형 기술과 제품이 연구되고 있다. 특히 국내 기준 전체 전력 소비량의 약 20%를 차지하는 조명분야에서는 기존 조명을 대체할 친환경, 고효율 LED 조명에 대한 기술이 대두되고 있다. LED 조명은 원리의 특성상 광효율과 비례하여 LED 접합부 온도가 상승하며 이는 광효율과 수명을 저하시킨다. 이에 다양한 방열기술이 LED 조명기술의 핵심이라 할 수 있다. 본 논문에서는 LED 모듈 접합부의 발열을 열전소자를 활용하여 열전발전 함으로써 에너지를 절감하고, 열회수를 통한 방열효과를 제공 하는 LED 조명을 제안한다.

• Journal of Institute of Control, Robotics and Systems
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• v.16 no.5
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• pp.469-475
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• 2010

This paper presents a method of classifying discolored defects of metal pads using geometric texture for AFVI (Automated Final Vision Inspection) systems. In PCB manufacturing process, the metal pads on PCB can be oxidized and discolored partly due to various environmental factors. Nowadays the discolored defects are manually detected and rejected from the process. This paper proposes an efficient geometric texture feature, SUTF (Symmetry and Uniformity Texture Feature) based on the symmetric and uniform textural characteristics of the surface of circular metal pads for automating AFVI systems. In practical experiments with real samples acquired from a production line, 30 discolored images and 1232 roughness images are tested. The experimental results demonstrate that the proposed method using SUTFs provides better performance compared to Gabor feature with 0% FNR (False Negative Rate) and 1.46% FPR (False Positive Rate). The performance of the proposed method shows its applicability in the real manufacturing systems.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.17 no.1
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• pp.684-692
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• 2016

In the manufacturing process of the LQFP/TQFP (Low-profile Quad Flat Package/Thin Quad Flat Package), the requirement of a 3 dimensional inspection is increasing rapidly and a 3D inspection of the shape of a chip has become an important report of quality control. This study developed a 3 dimensional measurement system based on PMP (Phase Measuring Profilometry) for an inspection of the LQFP/TQFP chip and image processing algorithms. The defects of the LQFP/TQFP chip were classified according to the dimensions. The 2 dimensional optical system was designed by the dorm illumination to achieve constant light distribution, In the 3 dimensional optical system, PZT was used for moving 90 degree in phase. The problem of 2 ambiguity was solved from the measured moir? pattern using the ambiguity elimination algorithm that finds the point of ambiguity and refines the phase value. The proposed 3D measurement system was evaluated experimentally.