• 한국음향학회:학술대회논문집
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• 한국음향학회 1993년도 학술논문발표회 논문집 제12권 1호
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• pp.169-173
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• 1993

In this paper, the features extraction of reflected signals from various type of defects existing in the solid has been studied by Wiener filtering technique. In this experiment, three types of the defect have been considered; a flat cut, a angular cut and a circular hole. All of the defects have the same size, 20mm in diameter and have been located at 45mm in depth from the aluminum surface. In the result of the experiment, it has been found that the wiener filtering technique used for features extraction from the reflected signal corresponding to each defect have been very effective for defect classification.

• 한국항해항만학회지
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• 제28권1호
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• pp.43-49
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• 2004

결함검사는 생산공정에 있어서 상품의 디자인과 함께 매우 중요한 부분으로서, 상품의 경쟁력을 높이는데 필수 불가결한 것이다. 만약, 실시간 결함검출이 상품에 대한 어떤 손상도 없이 할 수 있다면, 품질 및 공정의 효율적 관리와 고비용 인력의 절감을 통하여 생산원가를 줄일 수 있다. 본 논문에서는 철판과 같은 표면에 결함이 있는 경우 필요한 정보만을 추출할 수 있는 3가지 공간필터법에 대하여 제안하였고, 공간필터의 특성을 통하여 결함검출 시스템을 구성하였다. 그리고, 최적의 표면결함 계측용 공간필터법을 개발하기 위하여 결함의 크기와 형태, 광도의 크기 및 외부 광간섭 그리고 슬리트의 개수와 같은 파라메타의 변화에 따른 측정 성능을 비교 및 분석하였다.

• 설비공학논문집
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• 제27권3호
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• pp.174-178
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• 2015

This paper describes a signal processing technique for identifying signals from defects by using an electromagnetic-ultrasonic guided waves method based on a magnetostrictive sensor that generates a torsional mode (T(0, 1)). Because this technique is based on the digital filtering, the filtered signals provide information on the relationship between the cutoff frequency of band-pass filter and the characteristic of defect signals in heat exchange tubes. To verify the performance of the technique, artificial defects with various thickness reduction ration and shape were machined in titanium tubes, and digital filtering results are reported. The results show that digital filtering provides information to the identify shape of defects and the contact condition between the tube and support ring. Therefore, the proposed technique has good potential as a tool for evaluating the integrity of heat exchange tubes.

• 한국항해학회지
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• 제22권4호
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• pp.59-67
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• 1998

A quick and automatic detection with no harm to the goods is very important task for improving quality control, process control and labour reduction. In real fields of industry, defect detection is mostly accomplished by skillful workers. A narrow band eliminating spatial filter having characteristics of removing the specified spatial frequency is developed by the author, and it is proved that the filter has an excellent ability for on-line and real time detection of surface defect. By the way,. this spatial filter shows a ripple phenominum in filtering characteristics. So, it is necessary to remove the ripple component for the improvement of filter gain, moreover efficiency of defect detection. The spatial filtering method has a remarkable feature which means that it is able to set up weighting function for its own sake, and which can to obtain the best signal relating to the purpose of the measurement. Hence, having an eye on such feature, theoretical analysis is carried out at first for optimal design of narrow band eliminating spatial filter, and secondly, on the basis of above results spatial filter is manufactured, and finally advanced effectiveness of spatial filter is evaluated experimentally.

• 한국컴퓨터정보학회논문지
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• 제17권6호
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• pp.101-109
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• 2012

고 품질의 소프트웨어를 개발하기 위해서는 소프트웨어 내에 잠재된 결점을 제거하기 위한 품질관리계획이 요구된다. 이를 위해 결점 제거 프로필을 적절히 기술해야만 한다. 기존의 유조와 도관 모델은 결점이 제거되고 도피하는 결점을 계산하는데 복잡한 과정을 수행한다. 또한 어느 단계에서 삽입된 결점이 제거되고 도피하였으며, 단계별 결점 발견율이 얼마인지를 상세히 알고 있어야만 한다. 이러한 복잡한 과정을 단순화하기위해 본 논문은 결점필터링 개념에 기반하여 모델을 제시하였다. 제시된 모델은 임의의 단계에서 제거와 도피한 결점이 어느 단계에서 삽입된 결점에 관련되어 있는지 고려할 필요가 없어 결점을 보다 간략히 기술할 수 있는 장점이 있다. 또한, 결점 제거 품질척도와 생산성 척도의 함수에 기반하여 결점제거에 요구되는 노력 추정 모델을 제시하였다.

• 제어로봇시스템학회논문지
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• 제14권5호
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• pp.432-437
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• 2008

This paper proposes a defect cell extraction algorithm for TFT-LCD auto-repair system. Auto defect search algorithm and automatic defect cell extraction method are very important for TFT-LCD auto repair system. In the previous literature[1], we proposed an automatic visual inspection algorithm of TFT-LCD. Based on the inspected information(defect size and defect axis, if defect exists) by the automatic search algorithm, defect cells should be extracted from the input image for the auto repair system. For automatic extraction of defect cells, we used a novel block matching algorithm and a simple filtering process in order to find a given reference point in the LCD cell. The proposed defect cell extraction algorithm can be used in all kinds of TFT-LCD devices by changing a stored template which includes a given reference point. Various experimental results show the effectiveness of the proposed method.

• International Journal of Precision Engineering and Manufacturing
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• 제1권1호
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• pp.56-61
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• 2000

We present a fast inspection method of machine vision for in-line quality assurance of liquid crystal displays(LCD) and plasma display panels(PDP). The method incorporates an optical spatial filter in the Fourier plane of the imaging optics to block the normal periodic pattern, extracting only defects real time without relying on intensive software image process. Special emphasis is on designing a collimated white light source to provide high degree of spatial coherence for effective real time Fourier transform. At the same time, a low level of temporal coherence is attained to improve defect detection capabilities by avoiding undesirable coherent noises. Experimental results show that the proposed inspection method offers a detection accuracy of 15% tolerance, which is sufficient for industrial applications.

• 반도체디스플레이기술학회지
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• 제9권3호
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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.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2011년도 제42회 하계학술대회
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• pp.1790-1791
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• 2011

In this paper, the diagnosis system for detecting and localizing the neutral wire defect in an energized XLPE power cable is proposed. The neutral wire defect is detectd and localized by the time-frequency domain reflectometry. To extract the reflected signal from the neutral wire defect, the adaptive RLS filtering is introduced. To verify the proposed method, the experiments for detecting and localizing neutral wire defect in active XLPE power cable is conducted.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2003년도 ICCAS
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• pp.789-792
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• 2003

Pipe inspection has a great importance to ensure safety for the nuclear power plant. In this paper, we designed visual inspection module for the tube internal, which diameter is 15${\sim}$20mm. And we made inspection module which consisted of CCD camera and light. And the relation between image and real world coordinate is established. Image processing is performed to calculate mapping parameter and analyze the size of defect. For the calculation of mapping parameter, experiment is performed using grid type test pattern. Acquired image is processed to extract image coordinate. Edge detection, thresholding, median filtering and morphology filtering is applied to extract grid pattern. Extracted image coordinate is used to calculate image to real world mapping. Lens distortion was considered and corrected to get exact data. Coordinate transformation data is provided for the users to recognize easily. Experiment was performed using grid type test pattern, we extracted lens distortion parameter and real coordinate of defect point. Radial distortion of lens was corrected but tangential distortion was not considered. As continuum to this study, the tangential distortion of lens is considered and improvement of analy zing technique for the tube internal be explored continuously.