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웨이브렛 변환을 이용한 선형시스템 분석: 초음파 신호 해석의 응용
주영복,Joo, Young Bok 한국반도체디스플레이기술학회 2020 반도체디스플레이기술학회지 Vol.19 No.4
The Linear system analysis for physical system is very powerful tool for system diagnostic utilizing relationship between the input signal and output signal. This method utilized generally to investigate physical properties of system and the nondestructive test by ultrasonic signals. This method can be explained by linear system theory. In this paper the Continuous Wavelets Transform is utilized to search the relation between the linear system and continuous wavelets transform.
Automatic Inspection System for TFT-LCD Cell Defects Using Magnitude Spectrum
Young-Bok Joo(주영복),Hye-Seung Park(박혜승),Kyung-Moo Huh(허경무) 제어로봇시스템학회 2018 제어·로봇·시스템학회 논문지 Vol.24 No.9
Automatic vision inspection (AVI) systems automatically detect defect features and measure their sizes via camera-vision sensors. In this paper, a commercial automatic vision inspection system is developed by using a filter design based on magnitude spectrum analysis for defects on a TFT-LCD panel. All the inspection process’s modules, including image acquisition, the camera interface, and algorithms, are implemented and packed in a PCI-board that is equipped with FPGA and DSP processors. The system automatically inspects any abnormality on each cell, such as the level of brightness, possible cracks, and so on. However, cell patterns normally make inspection difficult. We propose an efficient and powerful algorithm to eliminate cell patterns by using magnitude spectrum analysis, which is followed by the main inspection.
LCD 구동 모듈 PCB의 자동 기능 검사를 위한 Emulated Vision Tester
주영복(Young-Bok Joo),한찬호(Chan-Ho Han),박길흠(Kil-Houm Park),허경무(Kyung-Moo Huh) 대한전자공학회 2009 電子工學會論文誌-SC (System and control) Vol.46 No.2
본 논문에서는 LCD 구동 모듈 PCB의 기능 검사를 위한 자동 검사 시스템인 EVT (Emulated Vision Tester)를 제안하고 구현하였다. 기존의 대표적인 자동검사 방법으로는 전기적 검사나 영상기반 검사방식이 있으나 전기적 검사만으로는 Timing이 주요한 변수가 되는 LCD 장비에서는 검출할 수 없는 구동불량이 존재하며 영상기반 검사는 영상획득에 일관성이 결여되거나 Gray Scale의 구분이 불명확하여 검출결과의 재현성이 떨어진다. EVT 시스템은 Pattern Generator에서 인가된 입력 패턴 신호와 구동 모듈을 통한 후 출력되는 디지털 신호를 직접 비교하여 패턴을 검사하고 아날로그 신호 (전압, 저항, 파형)의 이상 여부도 신속 정확하게 검사할 수 있는 하드웨어적인 자동 검사 방법이다. 제안된 EVT 검사기는 높은 검출 신뢰도와 빠른 처리 속도 그리고 간결한 시스템 구성으로 원가 절감 및 전공정 검사 자동화의 실현을 가능케 하는 등 많은 장점을 가진다. In this paper, an automatic functional inspection system EVT (Emulated Vision Tester) for LCD drive module PCB has been proposed and implemented. Typical automatic inspection system such as probing methods and vision-based systems are widely known and used, however, there exist undetectable defects due to critical timing factors which they may miss to catch from LCD equipments. Especially typical vision-based systems have inconsistency on acquisition of images so that distinction between gray scales can be difficult which results in low level of performance and reliability on the inspection results. The proposed EVT system is pure hardware solution. It directly compares pattern signals from a pattern generator to output signals from LCD drive module. It also inspects variety of analog signals such as voltage, resistance, wave forms and so forth. The EVT system not only shows high performance in terms of reliability and processing speed but reduces costs on inspection and maintenance. Also, full automation of entire production line can be realized when EVT is applied in in-line inspection processes.
주영복(Young-Bok Joo),허경무(Kyung-Moo Huh),박길흠(Kil-Houm Park) 대한전기학회 2009 정보 및 제어 심포지엄 논문집 Vol.2009 No.5
Automatic Vision Inspection (AVI) systems automatically detect defect features and measure their sizes via camera vision. It is important to predict the performance of an A VI to meet customer's specification in advance. In this paper, we propose a statistical method for prediction of false alarm rate regarding inconsistency of defect size measuremet process. We only need are a simple experimental trial for repeated defect size measurement test. The statistical features from the experiement are utilized in the prediction process. Therefore, the proposed method is swift and easy to implement and use. The experiment shows a close prediction compared to manual inspection results.
영상기반 자동결함 검사시스템에서 재현성 향상을 위한 결함 모델링 및 측정 기법
주영복(Young-Bok Joo),허경무(Kyung-Moo Huh) 제어로봇시스템학회 2013 제어·로봇·시스템학회 논문지 Vol.19 No.11
AVI (Automatic Vision Inspection) systems automatically detect defect features and measure their sizes via camera vision. AVI systems usually report different measurements on the same defect with some variations on position or rotation mainly because different images are provided. This is caused by possible variations from the image acquisition process including optical factors, nonuniform illumination, random noises, and so on. For this reason, conventional area based defect measuring methods have problems of robustness and consistency. In this paper, we propose a new defect size measuring method to overcome this problem, utilizing volume information that is completely ignored in the area based defect measuring method. The results show that our proposed method dramatically improves the robustness and consistency of defect size measurement.
왜곡에 강건한 강화학습 기반 차량번호판 자동인식 시스템
주영복(Young-Bok Joo),방준영(Joon-Young Bang),오승은(Seung-Eun Oh),허경무(Kyung-Moo Huh) 제어로봇시스템학회 2018 제어·로봇·시스템학회 논문지 Vol.24 No.4
The license plate recognition system has been an important part of modern traffic management extensively used such as illegal parking management signal violation speeding detection. However, it is operated under limited environments because of distortion of angles, shapes, and various kinds of license plates depending on the circumstances and conditions of various vehicles. In this paper, an intelligent, reliable and robust system is proposed to recognize vehicle license plates ensuring that the cognitive ability of the recognition can keep evolving itself by independent learning. The proposed system uses reinforcement learning methods which are known to be closet learning method for human learning and cognition. Experimental results show a level of robustness against the deterioration of distortion and various conditions such as angles, lightings and shapes.