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최종현(Jonghyun Choi),박종민(Jonmin Park),김근수(Keunsu Kim),김수지(S.J Kim),정화용(Hwayong Jung),윤병동(Byeng D. Youn) 대한기계학회 2018 대한기계학회 춘추학술대회 Vol.2018 No.12
Envelope analysis is most conventionally used for detection of rolling element bearing faults by bandpass filtering the raw signal and then extracting its envelope and then analyzing fault frequency energy by Fourier transform. However, traditional Envelope analysis based algorithm such as high frequency resonance technique and spectral kurtosis has limitation in extracting faulty signal and constructing optimal bandpass-filter. This paper employs empirical mode decomposition(EMD) to decompose signal and sort fault implemented signal and particle swarm optimization(PSO)to optimize bandpass filter. The performance of “EMD+PSO Envelope analysis” was checked under varying fault location and load condition by CWRU data, and varying operating speed and fault size by SNU data. It was shown that suggested algorithm successfully diagnose four commonly occur bearing fault location and also naturally formed distributed fault under different speed and loading condition. It was also shown that suggested algorithm presents much higher performance compare to three previously introduced Envelope analysis algorithm.
Jun Gao(고준),J.H. Choi(최종현),Y.S. Kueon(권영섭),Y.S. Baek(백윤수) 대한기계학회 2009 대한기계학회 춘추학술대회 Vol.2009 No.11
Hydraulic actuators are normally used in the systems requiring a large amount of motive force. However, when the system requires high frequency and fast response, it is hard to control the actuator which is shown to have low mechanical performance. Therefore direct-driven electromagnetic linear actuator system is demanded. This paper deals with a linear motor system which is replaced to achieve direct linear motion. The modeling has been done with Finite Element(FE) Analysis and two prototypes have been designed and fabricated. They are designed with moving-coil and moving-magnet type. Halbach array is used on the second type to reduce detent force. In this study, FE analytical results are validated by experiments. The results show that thrust force is about 6,000N and detent force is reduced to approximately 35N. The linear motor system presented in the work can be used for other devices, just like machine-tool sliding tables, continuous casters and so on.