• 융합신호처리학회논문지
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• 제5권2호
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• pp.165-171
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• 2004

반도체 IC의 소형화와 고 밀도화에 따르는 소자의 외관적 불량을 육안으로 식별하는 것이 거의 불가능하며, 불량요소도 다양하여 고 정밀 비젼시스템의 도입이 필수적인 제조공정으로 자리매김 되고 있다. 특히 리드의 뜸 상태검사는 망상처리 알고리즘의 구현이 어려운 점이 있다. 따라서 본 논문에서는 칩의 면적이 1cm${\times}$0.5cm인 SOP형 IC의 불량을 검출하는 외관검사 시스템을 구현하고, 그 성능을 평가하고자 한다. 여러 가지 항목을 최적으로 검사하기 위하여 기하적 길이, 간격, 각도, 명도 및 위치보정 등을 이론적으로 전개하였고, 시스템 구성을 위해 인터페이스 회로를 설계하여 Handler와 결합하였다. 그 결과 초당 2개의 IC를 검사하고, 화소 당 20$\mu$m의 분해능을 가지는 계측 정밀도를 확인하였다.

• 한국해양공학회:학술대회논문집
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• 한국해양공학회 2006년 창립20주년기념 정기학술대회 및 국제워크샵
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• pp.41-45
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• 2006

The fabrication process of fiber placement system of carbon fiber reinforced plastic (CFRP) requires real time process control and reliable inspection to ensure quality by preventing defects such as delamination and void. Therefore, novel non-contact inspection technique is required during the non-destructive evaluation in a fiber placement system. For the inspection of delamination in CFRP, various methods to receive laser-generated ultrasound were applied by using piezoelectric transducer, air-coupled transducer, wavelet transform and scanning laser ultrasonic technique. Laser-generated ultrasound was received with a conventional piezoelectric sensor in contacting manner. Then signal characteristics due to defects were analyzed to find a factor for detecting defects. Air-coupled transducer was used for reception of laser-generated guided wave using linear slit array in order to generate high frequency guided wave. And line scan technique was used to confirm the capability of on-line application. The high frequency component of laser-generated guided wave received with piezoelectric sensor disappeared after propagating through delamination region. Nevertheless, it was failed to receive high frequency guided wave in using air-coupled transducer. The first peak of the frequency spectrum under 100kHz in the delamination region is higher than in the sound region. By using this feature, the line scanned frequency data were acquired in fully non-contact generation and reception of ultrasound. This method was proved as useful technique for detecting delamination in CFRP.

• 전자공학회논문지B
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• 제32B권11호
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• pp.1445-1454
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• 1995

In this study, we have developed a prototype of the automatic defects detection system for capsule inspection using the computer vision techniques. The subjects for inspection are empty hard capsules of various sizes which are made of gelatine. To inspect both sides of a capsule, 2-stage recognition is performed. Features we have used are various lengths of a capsule, area, linearity, symmetricity, head curvature and so on. Decision making is performed based on average value which is computed from 20 good capsules in training and permission bounds in factories. Most of time-consuming process for feature extraction is computed by hardware to meet the inspection speed of more than 20 capsules/sec. The main logic for control and arithmetic computation is implemented using EPLD for the sake of easy change of design and reduction in time for developement. As a result of experiment, defects on size or contour of binary images are detected over 95%. Because of dead zone in imaging system, detection ratio of defects on surface, such as bad joint, chip, speck, etc, is lower than the former case. In this case, detection ratio is 50-85%. Defects such as collet pinch and mashed cap/body seldom appear in binary image, and detection ratio is very low. So we have to process the gray-level image directly in partial region.

• 한국정보처리학회논문지
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• 제7권3호
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• pp.992-999
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• 2000

Textile dimension inspection is one of the basic issues in the textile dyeing and finishing industry. And also, it a plays an important role in the quality control of total fabric products. In this paper, we implement a real-time textile dimension inspection system which detects various real defects, defects positions of textile and the density of textiles. The proposed method consists of textile density measurement algorithms with zone-occurrence features from subband image which detect various types of real defects. The performance of the proposed method is tested with a number of real textile samples with 10 types of defects and three basic structures of textile. By the dimension inspection of textile at continuous stages in the fabrication process, it is possible to measure the density of textile up to 150m/min and to detect the defect of textile at real time within $\pm$1% error percentages. And also it can be monitored the condition of textile throughout at all the significant working process and can be improved textile quality.

• 제어로봇시스템학회논문지
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• 제14권5호
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• pp.444-452
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• 2008

This paper presents an overall image processing approach of defect inspection of patterned TFT-LCD panels for the real manufacturing process. A prototype of AOI(Automatic Optical Inspection) system which is composed of air floating stage and multi line scan cameras is developed. Adjacent pattern comparison algorithm is enhanced and used for pattern elimination to extract defects in the patterned image of TFT-LCD panels. New region merging algorithm which is based on border expansion is proposed to identify defects from the pattern eliminated defect image. Experimental results show that a developed AOI system has acceptable performance and the proposed algorithm reduces environmental effects and processing time effectively for applying to the real manufacturing process.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2010년도 춘계학술대회 논문집
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• pp.571-582
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• 2010

전동차 중정비 시 대치차 기어의 비파괴검사 방법으로는 일반적으로 침투비파괴검사를 적용하고 있다. 침투비파괴검사는 결함의 미세한 개구부 속으로 침투액을 투입하여 표면에 잔류하는 여분의 침투액을 제거하고 현상제를 도포하여 결함지시 모양을 관찰하여 탐상하는 방법이다. 그러나 이 방법은 기어를 조립상태에서 침투비파괴검사를 실시하므로 많은 문제점이 있다. 치면의 각도가 급경사를 이루므로 충분한 침투가 어렵고 과잉제거의 문제가 있다. 그에 비해 자분비파괴검사는 표면 하 결함은 물론 미세한 결함 검출에 용이하다. 시험결과 치면에 응력이 집중되어 내부결함 및 미세결함이 존재하는 경우 침투비파괴검사로 발견되지 않는 경우가 있으나 자분비파괴 검사로 미세한 결함까지 발견 할 수 있었다. 따라서 전동차 대치차 기어의 합리적인 비파괴검사법은 자분을 사용한 비파괴검사가 적합하다고 판단한다.

• International Journal of Fuzzy Logic and Intelligent Systems
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• 제2권1호
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• pp.89-93
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• 2002

This paper introduces a vision-based on-line fabric inspection methodology of woven textile fabrics. Current procedure for determination of fabric defects in the textile industry is performed by human in the off-line stage. The advantage of the on-line inspection system is not only defect detection and identification, but also 벼ality improvement by a feedback control loop to adjust set-points. The proposed inspection system consists of hardware and software components. The hardware components consist of CCD array cameras, a frame grabber and appropriate illumination. The software routines capitalize upon vertical and horizontal scanning algorithms characteristic of a particular deflect. The signal to noise ratio (SNR) calculation based on the results of the wavelet transform is performed to measure any deflects. The defect declaration is carried out employing SNR and scanning methods. Test results from different types of defect and different style of fabric demonstrate the effectiveness of the proposed inspection system.

• 한국자동차공학회논문집
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• 제16권5호
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• pp.8-14
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• 2008

For nondestructive inspection of electron beam (EB) welding part in automotive power transmission assembly, a pulse-echo ultrasonic testing apparatus in water immersion has been applied using the ultrasonic waves with a frequency of 10MHz. However various problems have appeared during the ultrasonic inspection, which led to some significant mistakes in automatic quality evaluation of the welding parts. Experimental study showed that the state of water couplant medium containing some amount of contaminants, rusts and anti-corrosion agents had considerable influences on the reduction of ultrasonic amplitudes during wave propagation. The amplitude reduction depending on the coupling medium state could bring about some mis-diagnoses for defects in the welding parts. The results proposed that for a reliable inspection of defects in welds the state of water medium should be kept in about 15 volume fractions (vol.%) of anti-corrosion agents and in minimized contaminants.

• 한국산학기술학회논문지
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• 제15권6호
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• pp.3416-3422
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• 2014

쇼크 업쇼바의 로드는 피스톤부 중심에 위치하여 왕복운동을 담당하는 부분으로 표면의 불량(찍힘)이 있을 경우 감쇠력에 대한 차이로 제품 성능을 제대로 발휘하는데 문제 발생의 요인이 되고 있다. 로드표면은 열처리 상태로 표면 광택으로 인하여 쉽게 불량이 표시되지 않으며, 작업자가 육안으로 로드의 이물질 및 찍힘, 기포 검사를 진행함으로써 눈의 피로도가 높아지고, 작업자 육안에 의존하기 때문에 제품의 검사 품질이 일정하지 않다. 본 연구에서는 제품의 원통 형상을 고려하여 라인스캔카메라를 이용한 머신비전 영상처리 기법으로 0.3mm이상의 표면의 불량을 검출하고, 검사단계에서 발생할 수 있는 표면 불량을 최소화하기 위한 전 공정 자동이송 및 양불 제품의 혼입을 방지하는 자동검사 시스템 개발에 대한 연구를 수행하였다. 표면검사 시스템 개발로 작업자의 육안 검사에 의존하고 있던 쇼크업쇼버 로드의 표면에 대한 정밀 검사시스템 구축으로 품질검사 기준을 확보하고 표준화된 검사로 신뢰도가 향상되었다.

• 대한기계학회논문집A
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• 제31권6호
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• pp.651-658
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• 2007

A new tree-structured neural network classifier is proposed for the automatic real-time inspection of cold-rolled steel strip surface defects. The defects are classified into 3 groups such as area type, disk type, area & line type in the first stage of the tree-structured neural network. The defects are classified in more detail into 11 major defect types which are considered as serious defects in the second stage of neural network. The tree-structured neural network classifier consists of 4 different neural networks and optimum features are selected for each neural network classifier by using SFFS algorithm and correlation test. The developed classifier demonstrates very plausible result which is compatible with commercial products having high world-wide market shares.