• 대한전기학회:학술대회논문집
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• 대한전기학회 1999년도 하계학술대회 논문집 B
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• pp.668-670
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• 1999

We have developed a automatic surface inspection system for cold Rolled strips in steel making process for several years. We have experienced the various kinds of surface inspection systems, including linear CCD camera type and the laser type inspection system which was installed in cold rolled strips production lines. But, we did not satisfied with these inspection systems owing to insufficient detection and classification rate, real time processing performance and limited line speed of real production lines. In order to increase detection and computing power, we have used the Dark Field illumination with Infra_Red LED, Bright Field illumination with Xenon Lamp, Parallel Computing Processor with Area typed CCD camera and full software based image processing technique for the ease up_grading and maintenance. In this paper, we introduced the automatic inspection system and real time image processing technique using the Object Detection, Defect Detection, Classification algorithms. As a result of experiment, under the situation of the high speed processed line(max 1000 meter per minute) defect detection is above 90% for all occurred defects in real line, defect name classification rate is about 80% for most frequently occurred 8 defect, and defect grade classification rate is 84% for name classified defect.

• 한국정보통신학회논문지
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• 제14권1호
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• pp.225-232
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• 2010

용접부 내에 존재하는 결함의 형태, 위치, 크기 등의 정보를 정량적으로 파악하기 위하여 초음파 탐상 검사가 많이 활용되는데, 최근 들어 용접부의 결함 탐상을 위해, 검사과정을 기계적 스캐너로 자동화한 자동 초음파 탐상 시스템이 많은 산업 분야에서 활용되고 있고, 특히 배관 용접부의 건전성 평가를 위한 비파괴안전진단에서 그 활용 폭이 커지고 있다. 본 논문에서는 배관 용접부의 자동 초음파 검사를 위한 알고리즘 구현과 결함 영상을 보정하여 주는 결함영상 처리 시스템을 설계 및 구현하였다. 적용된 기법으로는 초음파 A-Scan 압축 알고리즘, Synthetic Aperture Focusing 알고리즘, 결함영상증폭 알고리즘과 이와 관련된 소프트웨어 설계 및 구현에 대하여 논한다.

• International journal of advanced smart convergence
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• 제8권3호
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• pp.39-45
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• 2019

This paper presents an optical technique for the three-dimensional (3D) shape inspection of micro solder balls used in ball-grid array (BGA) packaging. The proposed technique uses an optical source composed of spatially arranged light-emitting diodes (LEDs) and the results are derived based on the specular reflection characteristics of the micro solder balls for BGA A vision system comprising a camera and LEDs is designed to capture the reflected images of multiple solder balls arranged arbitrarily on a tray and the locations of the LED point-light-source reflections in each ball are determined via image processing, for shape inspection. The proposed methodology aims to determine the presence of defects in 3D BGA shape using the statistical information of the relative positions of multiple BGA balls, which are included in the image. The presence of the BGA balls with large deviations in relative position imply the inconsistencies in their shape. Experiments were conducted to verify that the proposed method could be applied to inspection without sophisticated mechanism and productivity problem.

• 전기학회논문지
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• 제66권10호
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• pp.1508-1515
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• 2017

This paper proposes the defect detection method for automatic inspection machines in printed circuit boards (PCBs) manufacturing system. The defects of PCB such as open, short, pin hole and scratch can be detected by comparing the standard image and the target image. The standard image is obtained from CAD file such as ODB++ format, and the target image is obtained by arranging, filtering and binarization of captured PCB image. Since the PCB size is too large and image resolution is too high, the image processing requires a lot of memory and computational time. The wavelet transform is applied to compress the standard and target images, which results in reducing the memory and computational time. To increase the inspection accuracy, we utilize the he HH-domain as well as LL-domain of the transformed images. Experimental results are finally presented to show the performance improvement of the proposed method.

• 디지털산업정보학회논문지
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• 제7권4호
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• pp.81-88
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• 2011

Mini Double Gears Frame is critical part of PDP and also produces couple hundred thousand every month. In the process of mass production, product inspection is very important process. Double Gear, one of the part of machine, was inspected by human eyes which caused mistakes and slow progress. To achieve the speed and accuracy the system was compensated by vision system which is inspecting automatically. The focus value is measured based on the fact that high contrast images have much high frequency edge information. High frequency term of the image is extracted using the high-pass filter and the sum of the high frequency term is used as the focus value. We used a Gaussian smoothing filter to reduce the noise and then measures the focus value using the modified Laplacian filter called a Sum modified Laplacian Focus values for the various lens positions are calculated and the position with the maximum focus value is decided as the focused position. The focus values calculated in various lens position showed the Gaussian distribution. We proposed a method to estimate the best focus position using the Gaussian curve fitting. Focus values of the uniform interval lens positions are calculated and the values are used to estimate the Gaussian distribution parameters to find the best focus position.

• 한국정보과학회논문지:컴퓨팅의 실제 및 레터
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• 제10권6호
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• pp.499-506
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• 2004

제안된 동판 표면 검사 시스템은 PC-기반으로 다중 스레드 기법과 다중 CPU를 이용해 동판 표면의 결함을 실시간으로 검사하는 시스템이다. 초고속 라인 스캔 카메라로 영상 취득 보드에 영상을 실시간으로 취득하여 처리할 때, 더블 버퍼링 방법으로 입출력과 처리가 동시에 수행되어 처리 속도를 높인다. 다중 스레드 기법에서는 시스템 자원 활용과 다중 스레드로 CPU의 사용을 최대화하여 실시간 처리하며, 다중 스레드 구조로도 실시간 처리가 어려운 경우에는 다중 CPU를 사용하여 이를 해결한다. 또한 동판 표면 영상에서 결함 검출하여 분류할 때, 실시간 처리를 만족시키기 위해서 결함영상의 공분산 행렬의 고유치 비율, 명암차 등의 연산으로 분류할 수 있는 방법을 제시한다. 결함의 검출은 조명 불균형에 대한 보상 처리가 적용된 다음 임계치에 의해 검출된다. 검출된 결함은 제안된 분류 방법으로 특징을 분석한 뒤 결함의 형태를 분류한다. 특징은 결함 너비와 고유치 비율, 명암차 등이 사용되었다. 제시된 방법을 검증하기 위해서 총 141개의 결함을 분류하는 실험이 진행되었고, 결과로는 89.4% 성공률을 보였다.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2004년도 ICCAS
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• pp.126-131
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• 2004

The popularity of flat-panel display(FPD), including plasma display panel(PDP) and liquid-crystal display(LCD), has given rise to the need to streamline their production. In these days, PDP is one of the most popular display devices because of its expansion of manufacturing process and simplicity. Bus electrodes, sustain electrodes, barrier ribs and RGB phosphors are patterned on PDP panel to display an image. Since a minute damage on the pattern can cause a serious defect to display, it is important to inspect the pattern precisely. In this paper, an automatic inspection system of repeated pattern in PDP panel has been introduced to find the defect, such as open, short, dirt, island, and so on. And the inspection system has been operated in the mass production line of PDP.

• International Journal of Fuzzy Logic and Intelligent Systems
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• 제6권2호
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• pp.95-99
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• 2006

A tape feeder of a SMD(Surface Mount Device) mounter is a device that sequentially feeds electronic components on a tape reel to the pick-up system of the mounter. As components are getting much smaller, feeding accuracy of a feeder becomes one of the most important factors for successful component pick-up. Therefore, it is critical to keep the feeding accuracy to a specified level in the assembly and production of tape feeders. This paper describes a tape feeder inspection system that was developed to automatically measure and to inspect feeding accuracy using machine vision. It consists of a feeder base, an image acquisition system, and a personal computer. The image acquisition system is composed of CCD cameras with lens, LED illumination systems, and a frame grabber inside the PC. This system loads up to six feeders at a time and inspects them automatically and sequentially. The inspection software was implemented using Visual C++ on Windows with easily usable GUI. Using this system, we can automatically measure and inspect the quality of ail feeders in production process by analyzing the measurement results statistically.

• 제어로봇시스템학회논문지
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• 제21권8호
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• pp.794-800
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• 2015

This paper describes the design for a defective product inspection device for the curved glass used in smart-phone. Cameras are used as inspection devices to find cracks in LCDs (Liquid Crystal Displays), PDPs (Plasma Display Panels), etc. The devices used to inspect the curved glass used in smart-phone consist of a camera, two back-light apparatus, an inspection apparatus main body, and an image processing program. Camera image calibration was performed to smooth an image taken with the camera, and as a result, the average error was less than 0.12 pixels. And the image of a smart-phone's curved glass taken with the camera was processed using the produced program. As a result, the program could correctly extract the cracks on the curved glass. Thus, it is thought that the designed inspection device can successful detect cracks in curved tempered glass.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2007년도 춘계학술대회A
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• pp.1553-1558
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• 2007

This paper presents a vision based autonomous inspection system for welding quality control of car sinking seat. In order to overcome the precision error that arises from a visible inspection by operator in the manufacturing process of a car sinking seat, this paper proposes the MVWQC (machine vision based welding quality control) system. This system consists of the CMOS camera and NI machine vision system. The image processing software for the system has been developed using the NI vision builder system. The geometry of welding bead, which is the welding quality criteria, is measured by using the captured image with median filter applied on it. Experiments have been performed to verify the proposed MVWQC of car sinking seat.