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Development of Guided Wave Simulator and Application to Sizing Methodologies of Pipe Wall Thinning
Fumio Kojima,Jun-ichi Tsubota 제어로봇시스템학회 2009 제어로봇시스템학회 국제학술대회 논문집 Vol.2009 No.8
This paper is concerned with structural health monitoring techniques for pipe wall thinning using ultrasonic guided wave methods. First, our inspection model can be represented by linear elastic systems on a cylindrical shell. Secondly, numerical scheme of in spection is developed by Fourier-Galerkin approximations. Thirdly, we propose a com-putational method for identifying position, range, and sizing off low accelerated corrosion(FAC). Finally, the effectiveness and validity are demonstrated through computational experiments.
Defiect Shape Recovering by Parameter Estimation Arising in Eddy Current Testing
Fumio Kojima 한국비파괴검사학회 2003 한국비파괴검사학회지 Vol.23 No.6
This paper is concerned with a computational method for recovering a crack shape of steam generator tubes of nuclear plants. Problemson the shape identification are discussed arising in the characterization of a structural defect in a conductor using data of eddy current inspection. A surface defect on the generator tube can be detected as a probe impedance trajectory by scanning a pancake type coil. First, a mathematical model of the inspection process is derived from the Maxwell's equation. Second, the input and output relation is given by the approximate model by virtue of the hybrid use of the finite element and boundary element method. In that model, the crack shape is characterized by the unknown coefficients of the B-spline function which approximates the crack shape geometry. Finally, a parameter estimation technique is proposed for recovering the crack shape using data from the probe coil. The computational experiments were successfully tested with the laboratory data.
Defect Shape Recovering by Parameter Estimation Arising in Eddy Current Testing
Kojima, Fumio The Korean Society for Nondestructive Testing 2003 한국비파괴검사학회지 Vol.23 No.6
This paper is concerned with a computational method for recovering a crack shape of steam generator tubes of nuclear plants. Problems on the shape identification are discussed arising in the characterization of a structural defect in a conductor using data of eddy current inspection. A surface defect on the generator tube ran be detected as a probe impedance trajectory by scanning a pancake type coil. First, a mathematical model of the inspection process is derived from the Maxwell's equation. Second, the input and output relation is given by the approximate model by virtue of the hybrid use of the finite element and boundary element method. In that model, the crack shape is characterized by the unknown coefficients of the B-spline function which approximates the crack shape geometry. Finally, a parameter estimation technique is proposed for recovering the crack shape using data from the probe coil. The computational experiments were successfully tested with the laboratory data.
AKINORI FURUSAWA,Fumio Kojima,ATSUSHI MORIKAWA 한국원자력학회 2015 Nuclear Engineering and Technology Vol.47 No.2
The aim of this work is to demonstrate a method for exciting and receiving torsional andlongitudinal mode guided waves with an electromagnetic acoustic transducer (EMAT) ringarray. First of all, a three-dimensional guided wave simulator is developed in order tonumerically analyze the propagation of the guided wave. The finite difference time domainmethod is used for the simulator. Second, two guided wave testing systems using an EMATring array are provided: one is for torsional mode (T-mode) guided wave and the other is forlongitudinal mode (L-mode). The EMATs used in the both systems are the same in design. A method to generate and receive the T- and L-mode guided waves with the same EMATis proposed. Finally, experimental and numerical results are compared and discussed. The results of experiments and simulation agree well, showing the potential of theEMAT ring array as a mode controllable guided wave transmitter and receiver
AUTOMATIC GENERATION OF SEQUENCE CONTROL PROGRAMS
Tetuji Gohi,Fumio Kojima,Hideo Obana,Hisayosi Sugimori,Hirosi Tsukimoto 대한전자공학회 1992 대한전자공학회 학술대회 Vol.1992 No.10
This paper describes the automatic generation of sequence control programs for DCS (Distributed Control System), PLC(Programable Logic Controller) and so on. Since there is no same manufacturing process, it is difficult to standardize sequence programs.<br/> We propose the automatic sequence control program generator which is CAD software using knowledge engineering technique.