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반도체 패키지의 마크문자 회전량 측정을 위한 고속 라돈 변환에 관한 연구
신균섭 ( Gyunseob Shin ),주효남 ( Hyonam Joo ),김상민 ( Sangmin Kim ),이정섭 ( Jung-seob Lee ) 한국정보처리학회 2010 한국정보처리학회 학술대회논문집 Vol.17 No.1
반도체 패키지 제조공정 중에는 제품에 일련번호를 인쇄하는 마킹공정이 있다. 마킹 공정에서 새겨진 문자는 해당 관리기준에 따라 관리되고 있는데 최근 반도체 패키지의 소형화에 따라 인쇄된 마크문자의 틀어짐 정도가 관리기준에 미달되는 문제가 발생되고 있다. 본 논문에서는 마크문자의 검사 항목 중 tilted mark(angle mark) 검사를 위한 회전량 측정방법으로 golden section searching 방법을 적용한 고속 라돈 변환(radon transform)방법을 제안한다. 실험에서는 제안한 방법이 일반적인 라돈 변환에 비해 최대 약 21 배의 회전량 측정속도가 향상되는 것을 확인하였다.
Low Contrast 특성을 갖는 LCD 편광필름 결함의 크기 자동 검출
박덕천(Duckchun Park),주효남(Hyonam Joo),류근호(Keun-Ho Rew) 제어로봇시스템학회 2008 제어·로봇·시스템학회 논문지 Vol.14 No.5
In this paper, segmenting and classifying low contrast defects on flat panel display is one of the key problems for automatic inspection system in practice. Problems become more complicated when the quality of acquired image is degraded by the illumination irregularity. Many algorithms are developed and implemented successfully for the defects segmentation. However, vision algorithms are inherently prone to be dependent on parameters to be set manually. In this paper, one morphological segmentation algorithm is chosen and a technique using frequency domain analysis of input images is developed for automatically selection the morphological parameter. An extensive statistical performance analysis is performed to compare the developed algorithms.
Fast Detection of Mura Defects Based on Modified Watershed Algorithm
Ye Jian Zhang(장엽검),Hyonam Joo(주효남),Joon Seek Kim(김준식) 제어로봇시스템학회 2017 제어·로봇·시스템학회 논문지 Vol.23 No.6
Many kinds of defects show up during the process of manufacturing display panels. However, mura defects are the most difficult to detect using the conventional image processing algorithms. Many factors cause mura defects to appear in display panels. When images are taken using cameras, mura defects normally show up as relatively dark or bright regions with no definite shape, no clear contours, and very low contrast against their surrounding background. When an imaged mura defect is relatively dark compared to its background, it can be considered a water catchment basin when the whole image is visualized in three dimensions (i.e., is topographically interpreted), and such catchment basins can be detected by watershed algorithms. In this paper, for the accurate segmentation of the mura region, the flooding step of the original watershed algorithm is carefully redesigned to detect the mura defect that exists both inside and at the boundary of an image. The depth of the catchment basins is recorded iteratively and then is used to segment the mura defects. The just noticeable difference (JND) technique is used to quantify the level of the mura defects. It is shown, by extensive experiments, that the proposed algorithm performs well, detecting very low-contrast mura defects, and quickly detects defects located anywhere in the image.
QFN 패키지의 Resin Bleed와 Melting 검출 알고리즘
왕명걸(Mingjie Wang),박덕천(Duckchun Park),주효남(Hyonam Joo),김준식(Joon-Seek Kim) 제어로봇시스템학회 2009 제어·로봇·시스템학회 논문지 Vol.15 No.9
There are many different types of surface defects on semiconductor Integrated Chips (IC’s) caused by various factors during manufacturing process, such as Scratch, Flash, Resin bleed, and Melting. These defects must be detected and classified by an inspection system for productivity improvement and effective process control. Among defects, in particular, Resin bleed and Melting are the most difficult ones to classify accurately. The brightness value and the shape of Resin bleed and Melting defects are so similar that normally it is difficult to classify the Resin bleed and Melting. In this paper, we propose a segmenting method and a set of features for detecting and classifying the Resin bleed and Melting defects.
반도체 부품 마크 미세 결함 검사를 위한 패턴 영역 분할 및 인식 방법
장유정(Yuting Zhang),이정섭(Jung-Seob Lee),주효남(Hyonam Joo),김준식(Joon-seek Kim) 제어로봇시스템학회 2010 제어·로봇·시스템학회 논문지 Vol.16 No.9
To inspect the defects of printed markings on the surface of IC package, the OCV (Optical Character Verification) method based on NCC (Normalized Correlation Coefficient) pattern matching is widely used. In order to detect the micro pattern defects appearing on the small portion of the markings, a Partitioned NCC pattern matching method was proposed to overcome the limitation of the NCC pattern matching. In this method, the reference pattern is first partitioned into several blocks and the NCC values are computed and are combined in these small partitioned blocks, rather than just using the NCC value for the whole reference pattern. In this paper, we proposed a method to decide the proper number of partition blocks and a method to inspect and combine the NCC values of each partitioned block to identify the defective markings.
확장된 피사계 심도 알고리즘에서 엣지 정보 분석에 의한 3차원 깊이 정보 추출 방법
강선우(Sunwoo Kang),김준식(Joon Seek Kim),주효남(Hyonam Joo) 제어로봇시스템학회 2016 제어·로봇·시스템학회 논문지 Vol.22 No.2
Recently, popularity of 3D technology has been growing significantly and it has many application parts in the various fields of industry. In order to overcome the limitations of 2D machine vision technologies based on 2D image, we need the 3D measurement technologies. There are many 3D measurement methods as such scanning probe microscope, phase shifting interferometry, confocal scanning microscope, white-light scanning interferometry, and so on. In this paper, we have used the extended depth of focus (EDF) algorithm among 3D measurement methods. The EDF algorithm is the method which extracts the 3D information from 2D images acquired by short range depth camera. In this paper, we propose the EDF algorithm using the edge informations of images and the average values of all pixel on z-axis to improve the performance of conventional method. To verify the performance of the proposed method, we use the various synthetic images made by point spread function(PSF) algorithm. We can correctly make a comparison between the performance of proposed method and conventional one because the depth information of these synthetic images was known. Through the experimental results, the PSNR of the proposed algorithm was improved about 1 ~ 30 dB than conventional method.
반동체 웨이퍼 고속 검사를 위한 GPU 기반 병열처리 알고리즘
박영대(Youngdae Park),김준식(Joon Seek Kim),주효남(Hyonam Joo) 제어로봇시스템학회 2013 제어·로봇·시스템학회 논문지 Vol.19 No.12
In a the present day, many vision inspection techniques are used in productive industrial areas. In particular, in the semiconductor industry the vision inspection system for wafers is a very important system. Also, inspection techniques for semiconductor wafer production are required to ensure high precision and fast inspection. In order to achieve these objectives, parallel processing of the inspection algorithm is essentially needed. In this paper, we propose the GPU (Graphical Processing Unit)-based parallel processing algorithm for the fast inspection of semiconductor wafers. The proposed algorithm is implemented on GPU boards made by NVIDIA Company. The defect detection performance of the proposed algorithm implemented on the GPU is the same as if by a single CPU, but the execution time of the proposed method is about 210 times faster than the one with a single CPU.
FPD용 컬러 필터의 수지 얼룩 결함 형상화에 관한 연구
권오민(Oh-Min Kwon),이정섭(Jung-Seob Lee),박덕천(Duckchun Park),주효남(Hyonam Joo),김준식(Joon-Seek Kim) 제어로봇시스템학회 2009 제어·로봇·시스템학회 논문지 Vol.15 No.8
Detecting defects on FPD (Flat Panel Display) color filter before the full panel is made is important to reduce the manufacturing cost. Among many types of defects, the low contrast blemish such as Suzi Mura is difficult to detect using standard CCD cameras. Even skilled inspectors in the inspection line can hardly identify such defects using bare eyes. To overcome this difficulty, point spectrometer has been used to analyze the spectrum to differentiate such defects [rom normal color fillers. However, scanning ever increasing-size color filters by a point spectrometer takes too long time to be used in real production line. We propose a system using a spectral camera which can be viewed as a line scan camera composed of an array of point spectrometers. Three types of lighting system that exhibit different illumination spectrums are devised together with a calibration method of the proposed spectral camera system. To visualize the defect areas, various processing algorithms to identify and to enhance the small differences in spectrum between defective and normal areas are developed. Experiments shows 85% successful visualization of real samples using the proposed system.
3차원 정보 추출을 위한 다평면 피사계 심도 확장 알고리즘 연구
최인호(In ho Choi),김준식(Joon Seek Kim),주효남(Hyonam Joo) 제어로봇시스템학회 2017 제어·로봇·시스템학회 논문지 Vol.23 No.5
The extended depth of focus (EDF) algorithm has been investigated by many researchers. Many algorithms exist to solve EDF problems, such as the Point-based algorithm and Area-based algorithm. However the existing algorithms suffer inaccurate measurement of object depths inherent to the filters they use. To solve this problem and to improve measurement accuracy, we propose an algorithm that utilizes more than one filter applied to the whole 3-dimensional input image data set. First, a set of filters that have the property of finding the focused pixel plane are collected. Then, three separate filters, one applied to each direction of the 3-dimensional input image data set, are selected from the filter set. Through extensive simulated experiments, we found that some filters being applied to a certain direction of the 3-dimensional data set results in improved measurement accuracy compared to that of conventional algorithms.