• 한국공작기계학회논문집
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• 제16권6호
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• pp.110-116
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• 2007

This paper presents a new technique to implement the real-time recognition for shapes and model number of parts based on an active vision approach. The main focus of this paper is to apply a technique of 3D object recognition for non-contacting inspection of the shape and the external form state of precision parts based on the pattern recognition. In the field of computer vision, there have been many kinds of object recognition approaches. And most of these approaches focus on a method of recognition using a given input image (passive vision). It is, however, hard to recognize an object from model objects that have similar aspects each other. Recently, it has been perceived that an active vision is one of hopeful approaches to realize a robust object recognition system. The performance is illustrated by experiment for several parts and models.

• 한국정밀공학회지
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• 제20권11호
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• pp.134-141
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• 2003

An industrial product is designed and fabricated, followed by the inspection process in order to check whether it is dimensionally tolerable or not. The machining process produces a part such as a mold or die, in which the three-dimensional coordinate might be measured by a CMM (Coordinate Measuring Machine) for assessment of its dimension. It is not ignorable, however, that a CMM measurement requires a lot of operating time and cost, which has led to many studies on the OMM system. The OMM system can be categorized into contact and non-contact types, and each of which has its own strengths and weaknesses. Non-contacting types generally utilize structured lights, sounds or magnetic fields. Though they show rather poor performance in positional accuracy, the measuring speed is faster than the contacting probes. This paper presents the development of an OMM system based on a non-contacting laser displacement sensing apparatus and CAD model. The system is composed of software modules of center-aligning and measuring, which has been operated and verified on a NC machining center on a shop floor.

• 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.

• 제어로봇시스템학회논문지
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• 제14권6호
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• pp.519-522
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• 2008

As industry of a semiconductor and LCD industry have been rapidly growing, precision technologies of machining such as etching and 3D measurement are required. Stylus has been important measuring method in traditional manufacturing process. However, its disadvantages are low measuring speed and damage possibility at contacting point. To overcome mentioned disadvantage, non-contacting measurement method is needed such as PMP(Phase Measuring Profilometry), WSI(white scanning interferometer) and Confocal Profilometry. Among above 3 well-known methods, WSI started to be applied to FPD(flat panel display) manufacturing process. Even though it overcomes 21t ambiguity of PMP method and can measure objects which has specular surface, the measuring speed and vibration coming from manufacturing machine are one of main issue to apply full automatic total inspection. In this study, We develop high speed WSI system and algorithm to reduce unknown noise. The developing WSI and algorithm are implemented to measure 3D surface of wafer. Experimental results revealed that the proposed system and algorithm are able to measure 3D surface profile of wafer with a good precision and high speed.

• 한국산업융합학회 논문집
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• 제17권2호
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• pp.77-83
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• 2014

This paper describes a new technology to develop the character recognition technology based on pattern recognition for non-contacting inspection optical lens slant or precision parts, and including external form state of lens or electronic parts for the performance verification, this development can achieve badness finding. And, establish to existing reflex data because inputting surface badness degree of scratch's standard specification condition directly, and error designed to distinguish from product more than schedule error to badness product by normalcy product within schedule extent after calculate the error comparing actuality measurement reflex data and standard reflex data mutually. Developed system to smallest 1 pixel unit though measuring is possible 1 pixel as $37{\mu}m{\times}37{\mu}m$ ($0.1369{\times}10-4mm^2$) the accuracy to $1.5{\times}10-4mm$ minutely measuring is possible performance verification and trust ability through an experiment prove.

• 비파괴검사학회지
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• 제26권2호
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• pp.84-89
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• 2006

레이저 초음파 검사 장치는 레이저빔을 이용하여 초음파 신호를 발생시키고 측정하는 비접촉식 결함 검사 장치이다. 이 장치는 펄스 레이저빔을 이용하여 광대역 주파수 범위를 갖는 초음파 신호를 발생시키고 작은 점으로 집속된 측정용 레이저빔을 이용하여 초음파 신호를 측정하므로 우수한 측정 분해능을 제공한다. 본 논문에서는 레이저 초음파의 표면파를 이용하여 표면 결함의 깊이를 측정하는 기법에 대한 연구를 수행하였다. 표면 결함은 깊이가 깊어질수록 차단 주파수 값이 작아지는 저주파 통과 필터 역할을 한다. 그리고 결함을 통과한 초음파 신호의 중심 주파수 값은 결함의 깊이에 따라 반비례적으로 작아진다. 본 논문에서는 표면 결함의 정규화 된 전달함수를 구한 다음 주파수 감쇠 성분을 이용하여 표면 결함의 깊이 정보를 추출하였고 표면 결함을 통과한 레이저 초음파 신호의 중심 주파수 값을 이용하여 결함의 릴이 정보를 추출하였다. 제안된 표면 결함 깊이 측정 방법은 초음파의 진폭 변화에 의한 결함 깊이 측정법보다 더욱 정밀한 정보를 제공하였다.

• 한국산업융합학회 논문집
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• 제16권4호
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• pp.113-117
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• 2013

This paper describes a new technology to develop the character recognition technology based on pattern recognition for non-contacting inspection optical lens slant or precision parts, and including external form state of lens or electronic parts for the performance verification, this development can achieve badness finding. And, establish to existing reflex data because inputting surface badness degree of scratch's standard specification condition directly, and error designed to distinguish from product more than schedule error to badness product by normalcy product within schedule extent after calculate the error comparing actuality measurement reflex data and standard reflex data mutually. Developed system to smallest 1 pixel unit though measuring is possible 1 pixel as $37{\mu}m{\times}37{\mu}m$ ($0.1369{\times}10-4mm^2$) the accuracy to $1.5{\times}10-4mm$ minutely measuring is possible performance verification and trust ability through an experiment prove.

• 한국정밀공학회지
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• 제29권1호
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• pp.48-55
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• 2012

Pressure vessels in vehicle industries, power plants, and chemical industries are often affected by flaw and defect generated inside the pressure vessels due to production processes or being used. It is very important to detect such internal defects of pressure vessel because they sometimes bring out serious problems. In this paper, an optical defect detection method using digital shearography is used. This method has advantages that the inspection can be performed at a real time measurement and is less sensitive to environmental noise. Shearography is a laser-based technique for full-field, non-contacting measurement of surface deformation (displacement or strain). The ultimate goal of this paper is to detect flaws in pressure vessels and to measure the lengths of the flaws by using unwrapping, phase images which are only obtained by Phase map. Through this method, we could decrease post-processing (next processing). Real length of a pixel can be calculated by comparing minimum and maximum unwrapping images with shearing angle. Through measuring several specimen defects which have different lengths and depths of defect, it can be possible to interpret quantitatively by calculating gray level.

• 비파괴검사학회지
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• 제22권1호
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• pp.53-58
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• 2002

계자코일에 흐르는 교류전류로 전자기장을 유도하고, 결함에 의하여 누설되는 자속을 간극을 갖는 헤드로 측정하여 결함을 검출하는 새로운 비파괴탐상장치를 구성하였다. 이 탑상장치는 비접촉으로 강자성체의 구조물 요소에 존재하는 표면결항을 검출하고, 그 크기를 평가하는데 적용할 수 있다. 본 논문은 강자성체에 도입한 2차원 표면결함에 적용하여 결함의 평가를 실시하였다. 또한 측정주파수와 lift-off가 이들 평가에 미치는 영향을 검토하였다. 결함은 전압 분포에서 최대치로 검출할 수 있고, 이 최대전압의 변화는 결함의 깊이가 증가함에 따라 증가한다. 결함의 최대전압은 주파수와 lift-off 의 영향을 받지만, 작은 깊이의 결함은 깊이와 전압이$(V_0/V_{ave})$의 관계로부터 선형적으로 예측할 수 있다.

• 비파괴검사학회지
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• 제25권2호
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• pp.95-102
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• 2005

원자력 발전소의 많은 배관부는 고온, 고압환경에서 적용되고 있어 환경적 및 기계적 요인에 의하여 부식결함이 빈번히 발생하고 있다. 이와 같은 부식 결함은 초음파 기법 등에 의하여 평가되어야 하고, 본 연구에서는 주사형 레이저 유도 초음파(SLS) 기법을 도입하여 배관부 부식결함의 영상화 기법을 적용하였다. 본 기법은 표면이 거칠거나 배관재와 같은 곡면의 표면에서 적용할 수 있는 장점이 있다. 한편 기존의 주사형 초음파 기법은 초음파 센서와 검사대상체 사이의 초음파 전달 매개체를 확보하기 위하여 시험편이 수침되거나 워터젯을 이용하였으나 주사형 레이저 초음파 기법은 광학적 기법을 이용하여 초음파를 발생시키므로 비접촉 방법에 의한 주사 이미지 획득이 가능하다. 따라서 본 주사형 레이저 초음파 기법은 복잡한 구조물의 검사, 비접촉 원격 및 고화질의 결함 이미지 탐상이 가능하다. 본 연구에서는 배관 결함의 검출능 향상을 위하여 결함 영상 획득에 있어서 다양한 조건의 레이저 유도 초음파 발생 기법을 적용하였고, 배관에 존재하는 응력부식 균열의 결함 영상을 얻게 되었다.