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미소결함의 형상인식을 위한 디지털 신호처리 적용에 관한 연구
김재열,홍석주,이규태,김병현,김훈조,김양중 韓國工作機械學會 2000 한국생산제조학회지 Vol.9 No.1
In this study, the classified researches the artificial and natural flaws in welding pails are performed using the pattern recognition technology. For this purpose the signal pattern recognition package including the user defined function was developed and the total procedure including the digital signal processing, feature extraction, feature selection and classifi-er selection is treated by bulk. Specially it is composed with and discussed using the statistical classifier such as the linear discriminant function the empirical Bayesian classifier. Also, the pattern recognition technology is applied to classifica-tion problem of natural flaw(i.e multiple classification problem - crack, lack of penetration, lack of fusion, porosity, and slag inclusion, the planar and volumetric flaw classification problem). According to this results, it is possible to acquire the recognition rate of 83% above even through it is different a little according to domain extracting the feature and the classifier.
신경회로망에 의한 용접 결함 종류의 정량적인 자동인식 시스템 개발에 관한 연구
김재열,김영석,김병현,유신,김훈조,정진홍 한국공작기계학회 1997 한국생산제조학회지 Vol.6 No.1
A neural network approach has been developed to determine the depth of a surface breaking crack in a steel plate from ultrasonic backscattering data. The network is trained by the use of feedforward three-layered network together with a back-scattering algorithm for error correction. The signal used for crack insonification is a mode converted 70˚ transverse wave. A numerical analysis of back scattered field is carried out based on elastic wave theory, by the use of the boundary element method. The numerical data are calibrated by comparison with experimental data. The numerical analysis provides synthetic data for the training of the network. The training data have been calculated for cracks with specified increments of the crack depth. The performance of the network has been tested on other synthetic data and experimental data which are different form the training data.
곽이구,한재호,김홍건,김재열,김훈조 한국공작기계학회 2006 한국공작기계학회 추계학술대회논문집 Vol.2006 No.-
This paper wishes to develop system that measure an external diameter of optical-ferrule and roundness that is optical connection parts that is necessary in optical communication net construction that increase rapidly present automatically and plan productivity elevation and personnel expense curtailment. There is LC, PC, MU, and so on various form in the case of optical-ferrule and Recently, ferrule that have special form is appearing. Hereupon, can bring cost reduction by productivity elevation, measurement quality elevation, number of persons attrition and parts loss amount decrease etc. by computerizing measurement work of examination process that depended on existing manual processing by developing exterior diameter of LC ferrule and roundness' measurement system. Also, use of LD and PD ferrule by country and universal FTTH business is increasing, and LC optical ferrule that is necessary to laser packaging of inside depends on income. Therefore, productivity improvement of LC ferrule can contribute in could do to maximize income substitution effect country industry development. But, manual processing dependence of examination process that it selects LC ferrule manufacturing process defective goods that productivity does not increase because is high productivity elevation decrease bring. Therefore, productivity elevation of LC ferrule wishes to solve productivity decrease by existent manual processing computerizing external diameter and roundness measurement examination process.
MSBS-SPR Integrated System Allowing Wider Controllable Range for Effective Wind Tunnel Test
Yeol-Hun Sung,Dong-Kyu Lee,Jong-Seob Han,Ho-Young Kim,Jae-Hung Han 한국항공우주학회 2017 International Journal of Aeronautical and Space Sc Vol.18 No.3
This paper introduces an experimental device which can measure accurate aerodynamic forces without support interference in wide experimental region for wind tunnel test of micro aerial vehicles (MAVs). A stereo pattern recognition (SPR) method was introduced to a magnetic suspension and balance system (MSBS), which can eliminate support interference by levitating the experimental model, to establish wider experimental region; thereby MSBS-SPR integrated system was developed. The SPR method is non-contact, highly accurate three-dimensional position measurement method providing wide measurement range. To evaluate the system performance, a series of performance evaluations including SPR system measurement accuracy and 6 degrees of freedom (DOFs) position/attitude control of the MAV model were conducted. This newly developed system could control the MAV model rapidly and accurately within almost 60mm for translational DOFs and 40deg for rotational DOFs inside of 300 × 300mm test section. In addition, a static wind tunnel test was conducted to verify the aerodynamic force measurement capability. It turned out that this system could accurately measure the aerodynamic forces in low Reynolds number, even for the weak forces which were hard to measure using typical balance system, without making any mechanical contact with the MAV model.