• 제목/요약/키워드: Illumination Threshold

검색결과 79건 처리시간 0.022초

Machine Vision을 이용한 자동차용 Oil-Seal의 불량 검사 기계 개발 (Development of an Inspection Machine for Automotive Oil-Seals Using Machine Vision)

  • 노병국;김도형;박용국
    • 한국자동차공학회논문집
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    • 제12권3호
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    • pp.184-191
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    • 2004
  • In this study, an inspection system for automotive parts using machine vision has been developed and presented. The system is comprised of six analog CCD cameras, frame grabber, and mechanism that loads the automotive parts to the system for the inspection. An Image processing algorithm for detecting eight different types of defects of oil-seals are developed, and the effectiveness of the algorithm is experimentally verified. Inspection process is completed in 1 second with acceptable accuracy. It is envisaged that this inspection system will have a wide application in the automotive part manufacturing industry in the future.

수중 로봇을 위한 다중 템플릿 및 가중치 상관 계수 기반의 물체 인식 및 추종 (Multiple Templates and Weighted Correlation Coefficient-based Object Detection and Tracking for Underwater Robots)

  • 김동훈;이동화;명현;최현택
    • 로봇학회논문지
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    • 제7권2호
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    • pp.142-149
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    • 2012
  • The camera has limitations of poor visibility in underwater environment due to the limited light source and medium noise of the environment. However, its usefulness in close range has been proved in many studies, especially for navigation. Thus, in this paper, vision-based object detection and tracking techniques using artificial objects for underwater robots have been studied. We employed template matching and mean shift algorithms for the object detection and tracking methods. Also, we propose the weighted correlation coefficient of adaptive threshold -based and color-region-aided approaches to enhance the object detection performance in various illumination conditions. The color information is incorporated into the template matched area and the features of the template are used to robustly calculate correlation coefficients. And the objects are recognized using multi-template matching approach. Finally, the water basin experiments have been conducted to demonstrate the performance of the proposed techniques using an underwater robot platform yShark made by KORDI.

MTFA에 의한 칼라 CRT의 화질 평가 (Evaluation of color CRT monitor by MTFA)

  • 김태희
    • 한국광학회지
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    • 제9권3호
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    • pp.205-211
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    • 1998
  • 칼라 CRT(cathode ray tube)의 화질을 평가하기 위하여 일차원 CCD(charge coupled-device)를 사용한 MTF(modulation transfer function)측정장치를 구성하였다. CCD의 분광감도와 화소의 크기와 간격을 고려하여 MTF 측정값을 보정하였다. Spot 크기, 비디오 대역폭, 새도우 마스크, 디스플레이 휘도, 그리고 주변 조명이 디스플레이의 미치는 영향에 대하여 연구하였다. 칼라 CRT 모니터에서 화면의 균일성과 주변 조명에 따른 화질 평가하였으며, 그 결과를 MTFA(modulation transfer function area)를 사용하여 나타내었다.

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비젼 시스템을 이용한 LCD용 편광 필름의 결함 검사에 관한 연구 (A study on the defect inspection on the LCD polarizer film using the Vision system)

  • 박종성;정규원;강찬구
    • 한국공작기계학회:학술대회논문집
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    • 한국공작기계학회 2002년도 추계학술대회 논문집
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    • pp.164-169
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    • 2002
  • Recently, LCD(Liquid Crystal Display) is the display product widely used on various fields of industry. This is generally composed of many parts. Among many parts, polarizer film control the intensity of the transmitted light according to the degree of rotation of the polarizer axis. Therefore, this film must be free from defects. But it contains many defects such as the defects caused by dust or different thing, adhesive badness, scratch. Presently, the inspection of these defects is depending on the sight of operator. In this paper, we propose the vision system composed of telecentric lens and optical mirror. This system use the coaxial illumination and the light is specularly reflected on the optical mirror. And we develop the image processing algorithm using the threshold and morphological technique.

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Using Kalman Filtering and Segmentation Techniques to Capture and Detect Cracks in Pavement

  • Hsu, C.J.;Chen, C.F.
    • 대한원격탐사학회:학술대회논문집
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    • 대한원격탐사학회 2003년도 Proceedings of ACRS 2003 ISRS
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    • pp.930-932
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    • 2003
  • For this study we used a CCD video camera to capture the pavement image information via the computer. During investigation processing, the CCD video camera captured 10${\sim}$30 images per second. If the vehicle velocity is too fast, the collected images will be duplicated and if the velocity is too slow there will be a gapped between images. Therefore, in order to control the efficiency of the image grabber we should add accessory tools such as the Differential Global Positioning System (DGPS) and odometer. Furthermore, Kalman Filtering can also solve these problems. After the CCD video camera captured the pavement images, we used the Least-Squares method to eliminate images of gradation which have non-uniform surfaces due to the illumination at night. The Fuzzy Entropy method calculates images of threshold segments and creates binary images. Finally, the Object Labeling algorithm finds objects that are cracks or noises from the binary image based on volume pixels of the object. We used these algorithms and tested them, also providing some discussion and suggestions.

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입술영역 분할을 위한 CIELuv 칼라 특징 분석 (Analysis of CIELuv Color feature for the Segmentation of the Lip Region)

  • 김정엽
    • 한국멀티미디어학회논문지
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    • 제22권1호
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    • pp.27-34
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    • 2019
  • In this paper, a new type of lip feature is proposed as distance metric in CIELUV color system. The performance of the proposed feature was tested on face image database, Helen dataset from University of Illinois. The test processes consists of three steps. The first step is feature extraction and second step is principal component analysis for the optimal projection of a feature vector. The final step is Otsu's threshold for a two-class problem. The performance of the proposed feature was better than conventional features. Performance metrics for the evaluation are OverLap and Segmentation Error. Best performance for the proposed feature was OverLap of 65% and 59 % of segmentation error. Conventional methods shows 80~95% for OverLap and 5~15% of segmentation error usually. In conventional cases, the face database is well calibrated and adjusted with the same background and illumination for the scene. The Helen dataset used in this paper is not calibrated or adjusted at all. These images are gathered from internet and therefore, there are no calibration and adjustment.

Correlation between spin density and Vth instability of IGZO thin-film transistors

  • Park, Jee Ho;Lee, Sohyung;Lee, Hee Sung;Kim, Sung Ki;Park, Kwon-Shik;Yoon, Soo-Young
    • Current Applied Physics
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    • 제18권11호
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    • pp.1447-1450
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    • 2018
  • The electron spin resonance (ESR) detects point defect of the In-Ga-Zn oxide (IGZO) like singly ionized oxygen vacancies and excess oxygen, and get spin density as a parameter of defect state. So, we demonstrated the spin density measurement of the IGZO film with various deposition conditions and it has linear relationship. Moreover, we matched the spin density with the total BTS and the threshold voltage ($V_{th}$) distribution of the IGZO thin film transistors. The total BTS ${\Delta}V_{th}$ and the $V_{th}$ distribution were degraded due to the spin density increases. The spin density is the useful indicator to predict $V_{th}$ instability of IGZO TFTs.

선삭에서 컴퓨터비젼을 이용한 플랭크 마모 측정에 관한 연구 (A study on the measurement of flank wear by computer vision in turning)

  • 김영일;유봉환
    • 한국정밀공학회지
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    • 제10권3호
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    • pp.168-174
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    • 1993
  • A new digital image processing method for measuring of the flank wear of cutting tool is presented. The method is based on computer vision technology in which the tool is illuminated by two halogen lamps and the wear zone is visualized using a CCD camera. The image is converted into digital pixel and processed to detect the wearland width. As a conclusion, it has been proved that the average wearland area and mzximum peak values of the flank wear width can monitored effectively to a measuring resolution of 0.01mm.

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Photofield-Effect in Amorphous In-Ga-Zn-O (a-IGZO) Thin-Film Transistors

  • Fung, Tze-Ching;Chuang, Chiao-Shun;Nomura, Kenji;Shieh, Han-Ping David;Hosono, Hideo;Kanicki, Jerzy
    • Journal of Information Display
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    • 제9권4호
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    • pp.21-29
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    • 2008
  • We studied both the wavelength and intensity dependent photo-responses (photofield-effect) in amorphous In-Ga-Zn-O (a-IGZO) thin-film transistors (TFTs). During the a-IGZO TFT illumination with the wavelength range from $460\sim660$ nm (visible range), the off-state drain current $(I_{DS_off})$ only slightly increased while a large increase was observed for the wavelength below 400 nm. The observed results are consistent with the optical gap of $\sim$3.05eV extracted from the absorption measurement. The a-IGZO TFT properties under monochromatic illumination ($\lambda$=420nm) with different intensity was also investigated and $I_{DS_off}$ was found to increase with the light intensity. Throughout the study, the field-effect mobility $(\mu_{eff})$ is almost unchanged. But due to photo-generated charge trapping, a negative threshold voltage $(V_{th})$ shift is observed. The mathematical analysis of the photofield-effect suggests that a highly efficient UV photocurrent conversion process in TFT off-region takes place. Finally, a-IGZO mid-gap density-of-states (DOS) was extracted and is more than an order of magnitude lower than reported value for hydrogenated amorphous silicon (a-Si:H), which can explain a good switching properties observed for a-IGZO TFTs.

SiO2 완충층 두께에 따른 비정질 InGaZnO Pseudo-MOS Field Effect Transistor의 신뢰성 평가 (Effect of SiO2 Buffer Layer Thickness on the Device Reliability of the Amorphous InGaZnO Pseudo-MOS Field Effect Transistor)

  • 이세원;황영현;조원주
    • 한국전기전자재료학회논문지
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    • 제25권1호
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    • pp.24-28
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    • 2012
  • In this study, we fabricated an amorphous InGaZnO pseudo-MOS transistor (a-IGZO ${\Psi}$-MOSFET) with a stacked $Si_3N_4/SiO_2$ (NO) gate dielectric and evaluated reliability of the devices with various thicknesses of a $SiO_2$ buffer layer. The roles of a $SiO_2$ buffer layer are improving the interface states and preventing degradation caused by the injection of photo-created holes because of a small valance band offset of amorphous IGZO and $Si_3N_4$. Meanwhile, excellent electrical properties were obtained for a device with 10-nm-thick $SiO_2$ buffer layer of a NO stacked dielectric. The threshold voltage shift of a device, however, was drastically increased because of its thin $SiO_2$ buffer layer which highlighted bias and light-induced hole trapping into the $Si_3N_4$ layer. As a results, the pseudo-MOS transistor with a 20-nm-thick $SiO_2$ buffer layer exhibited improved electrical characteristics and device reliability; field effective mobility(${\mu}_{FE}$) of 12.3 $cm^2/V{\cdot}s$, subthreshold slope (SS) of 148 mV/dec, trap density ($N_t$) of $4.52{\times}1011\;cm^{-2}$, negative bias illumination stress (NBIS) ${\Delta}V_{th}$ of 1.23 V, and negative bias temperature illumination stress (NBTIS) ${\Delta}V_{th}$ of 2.06 V.