• Tribology and Lubricants
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• 제26권6호
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• pp.341-345
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• 2010

The NAUT(Non contact Air coupled Ultrasonic Testing) is one of the ultrasonic wave inspection methods. It compensates High power ultrasound Pulser Receiver, pre-amp, air probe of high sensitivity in air to generate loss energy by NAUT methods. Generally, in case of ultrasound inspection, it applies contact methods by using couplant. However it can inspect of UT without couplant by this NAUT. The ultrasound transmission reception is composed in stable condition in NAUT. It can inspect high low material or the specimen of rough part, the narrow spot, too. The spot welding is applying the inosculation of automobile component, car body, all boards. The CFRP is necessity of NDE because of the solidity changes material according to lamella tearing. Therefore it checked on realization whether and commercialization in the spot welding and CFRP inspection that the NAUT would be applied them.

• 한국레이저가공학회지
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• 제2권3호
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• pp.19-31
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• 1999

This paper introduces the monitoring scheme of laser welding quality using neural network. The developed monitoring scheme detects light signal emitting from plasma formed above the weld pool with optic sensor and DSP-based signal processor, and analyzes to give a guidance about the weld quality. It can automatically detect defects of laser weld and further give an information about what kind of defects it is, specially partial penetration and porosity among the interior defects. Those could be detected only by naked eyes or X-ray after welding, which needs more processes and costs in mass production. The monitoring scheme extracts four feature vectors from signal processing results of optical measuring data. In order to classify pattern for extracted feature vectors and to decide defects, it uses single-layer neural network with perceptron learning. The monitoring result using only the first feature vector shows confidence rate in recognition of 90%($\pm$5) and decides whether normal status or defects status in real time.

• 한국공작기계학회논문집
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• 제15권2호
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• pp.87-92
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• 2006

This paper supplements shortcoming of radioactivity check by detecting defect of SWP weld zone using ultrasonic wave. Manufacture 2 stage robot detection systems that can follow weld bead of SWP by method to detect weld defects of SWP that shape of weld bead is complex for this as quantitative. Also, through signal processing ultrasonic wave defect signal system of GUI environment that can grasp easily existence availability of defect because do videotex compose. Ultrasonic wave signal of weld defects develops artificial intelligence style sightseeing system to enhance pattern recognition of weld defects and the classification rate using neural net. Classification of weld defects that do fan Planar defect and that do volume defect of by classify.

• 한국정보통신학회:학술대회논문집
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• 한국해양정보통신학회 2008년도 추계종합학술대회 B
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• pp.520-523
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• 2008

최근까지 전자정보산업의 발달로 자동 초음파검사 하드웨어는 갈수록 경량화 되어 가고 있고, 소프트웨어는 다양한 최신 이미지 처리 기법이 적용되어 정확한 결함 위치 및 크기 측정이 가능하도록 연구되어지고 있다. 본 논문에서는 원전 배관 자동 검사에 최적화된 시스템을 구성하기 위해 배관자동 초음파 검사 시스템을 제안하고, 시스템 설계를 위해 소프트웨어의 데이터 흐름과 일반적인 구성에 대해서 기술한다.

• Journal of Welding and Joining
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• 제17권6호
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• pp.100-107
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• 1999

In this paper, we deal with the speckle noise reduction and parameter estimation of ultrasonic NDT(non-destructive test) signals obtained during weld inspection of piping. The overall approach consists of three major steps, namely, speckle noise analysis, proposition of wavelet domain AR(autoregressive) model and flaw detection by proposed model parameter. The data are first processed whereby signals obtained using vertical and angle beam transducer. Correlation properties of speckle noise are then analyzed using multiresolution analysis in wavelet domain. The parameter estimation curve obtained using the proposed model is classified a flaw in weld region where is contaminated by severe speckle noise and also clear flaw signal is obtained through CA-CFAR threshold estimator that is a nonlinear post-processing method for removing the noise from reconstructed ultrasonic signal.

• 비파괴검사학회지
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• 제2권1호
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• pp.10-16
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• 1982

This study was carried out to measure the flaw height of welds in consideration of the effective probe angle in ultrasonic oblique detection. Specimens with inserted artificial flaws were made and flaw heights were estimated from detecting these specimens. Two different methods were applied to estimate flaw heights. From the result of the experiment, flaw height could be measured within the accuracy of 15% percent error and the difference between the probe distance method and beam path method is about 5% relatively small. It is considered that the results obtained this experimental study could be helpful informal ions for measuring flaw height.

• 해양환경안전학회지
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• 제3권2호
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• pp.13-21
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• 1997

This paper describes the effectiveness of laser pulse shaping in eliminating weld defects such as porosity, cracks and undercuts in pulsed Nd:YAG Laser welding. A large porosity was formed in a keyhole mode of deep penetration weld metal of any stainless steel. Solidification cracks were present in Type 303 with about 0.3%s. The conditions for the formation of porosity were determined in further detail in Type 316. With the objectives of obtaining a fundamental knowledge of formation and prevention of weld defects, the fusion and solidification behavior of a molten puddle was observed during laser spot welding of Type 310S. through high speed video photographing technique. It was deduced that cellular dendrite tips grew rapidly from the bottom to the surface, and consequently residual liquid remained at the grain boundaries in wide regions and enhanced the solidification cracking susceptibility. Several laser pulse shapes were investigated and optimum pulse shapes were proposed for the reduction and prevention of porosity and solidification cracking.

• 한국구조물진단유지관리공학회 논문집
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• 제2권1호
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• pp.98-107
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• 1998

There are many weld defects such as surface crack, lack of fusion, and imcomplete penetration in the butt joint of the existing steel bridges. The crack-like defects may significantly reduce the fatigue life of the structure. This paper presents the procedure and the results of the fatigue assessment of the butt joints with weld defect in the existing steel girder bridge. The butt joints with imcomple penetration were instrumented with strain gages to determine the stress histogram under normal traffic. Based on the measured stress histogram the crack propagation analyses were performed for the fatigue assesment. By using the suggested procedure and methodology, one can decide the time of periodic inspection and the necessity of repair of the butt joints with serious weld defects in the existing steel bridge.

• 한국안전학회지
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• 제11권4호
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• pp.29-33
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• 1996

In this study, specimens were prepared which have some defects on the buttweld joint of mild steel. In order to detect the defects of specimens, the following tests were put to : AUT and RT. When the results of the three tests were compared, the conclusion could be brought to as follows. 1) AUT outstrips RT in the abillity to detect plane defects like slags or cracks, but RT excels AUT in the ability to detect spheroidal defects like blowholes. 2) RT detects neither taper cracks nor very closed cracks, whereas AUT detects both of them. 3) AUT can detect at once plane defects like cracks and spheroidal defects like blowholes.

• Journal of Welding and Joining
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• 제7권3호
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• pp.36-43
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• 1989

The furnace brazing in a Ar of copper to martensitic stainless steel(13.5Cr) using Cu-(5~8%)P-(0~8%)Sn powders was investigated. Shear strength, wettability, reacted layer, defect ratio at the stainless steel interface was evaluated. As Sn was added to the Cu-P powders, defect ratio and P content at the stainless steel interface decreased. And also as Sn was added, defect form at the stainless steel interface changed from the continuous layer to the discrete type, and shear strength of the brazed joint increased.