| Title |
Adaptive Cone-Kernel Time-Frequency Distribution for Analyzing the Pipe-Thinning in the Secondary Systems of NPP |
| Authors |
김정택(Kim, Jung-Taek) ; 이상정(Lee, Sang-Jeong) ; 이철권(Lee, Cheol-Kwon) |
| Keywords |
파이프 감육상태 분석 ; 진동신호 해석 ; 시간-주파수 해석 ; 적응 콘-커널 분포함수 ; Shannon의 엔트로피 ; |
| Abstract |
The secondary system of nuclear power plants consists of sophisticated piping systems operating in very aggressive erosion and corrosion environments, which make a piping system vulnerable to the wear and degradation due to the several chemical components and high flow rate (~10 m/sec) of the coolant. To monitor the wear and degradation on a pipe, the vibration signals are measured from the pipe with an accelerometer For analyzing the vibration signal the time-frequency analysis (TFA) is used, which is known to be effective for the analysis of time-varying or transient signals. To reduce the inteferences (cross-terms) due to the bilinear structure of the time-frequency distribution, an adaptive cone-kernel distribution (ACKD) is proposed. The cone length of ACKD to determine the characteristics of distribution is optimally selected through an adaptive algorithm using the normalized Shannon's entropy And the ACKD's are compared with the results of other analyses based on the Fourier Transform (FT) and other TFA's. The ACKD shows a better signature for the wear/degradation within a pipe and provides the additional information in relation to the time that any analysis based on the conventional FT can not provide. |