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기어 정렬불량에 의한 전류, 진동 및 음향방출 신호의 비교 분석
구동식(DongSik Gu),이정환(JeongHwan Lee),김병수(ByeongSu Kim),양보석(BoSuk Yang),최병근(ByeongKeun Choi) 대한기계학회 2008 대한기계학회 춘추학술대회 Vol.2008 No.11
To detect the failures in machine, the signals of current, vibration and acoustic emission are widely used in industry. And unexpected failures of gears are not only extremely damaging but also lead to economic losses. In this paper, to detect the misalignment occurred at between two gears in gearboxes, the signals of current, vibration and AE were measured at gearbox and motor power line. FFT(Fast Fourier Transform) was used for current and vibration signal analysis to find gear failure frequency. Especially, the envelop analysis and wavelet transform were applied for AE signal. Therefore, compared with the results of three kinds of signal, the possibility of earily detection by AE is identified or checked.
AE 신호를 위한 새로운 DWT 기저함수 제안 및 적용
구동식(DongSik Gu),김재구(JaeGu Kim),최병근(Byeong Keun Choi) 한국소음진동공학회 2011 한국소음진동공학회 학술대회논문집 Vol.2011 No.4
Acoustic Emission(AE) is widely used for early detection of faults for rotating machinery in these days because of its high sensitivity. AE signal has to need for transferring to low frequency range for the spectrum analysis included the fault mechanism. In transferring process, we lose a lot of fault information caused by unusable signal processing method. Discrete Wavelet Transform(DWT) is a method of signal processing for AE signatures, but the pattern of its mother function is not optimized with AE signals. So, we can lose the fault information when we want to use the DWT for AE signal. Therefore, in this paper, we will propose a novel pattern for DWT mother function, which is optimized with AE signals. And it will be applied to compare the results of DWT by daubechie and novel pattern.
회전기계 상태감시에서 균열진전에 의해 발생되는 AE신호의 파형 평가
김재구(Jae-Gu Kim),구동식(DongSik Gu),박원조(WonJo Park),최병근(Byeong-Keun Choi) 대한기계학회 2009 대한기계학회 춘추학술대회 Vol.2009 No.11
The Acoustic Emission (AE) technique is a well-known non-destructive evaluation technique. Condition monitoring using AE has to pass that reduces the noise level. Recently, in condition monitoring field, it has been used to detect faults in machines. Especially, the signal of crack in shaft is included in high level noise. So, the noise level has to be reduced to find the AE signal caused by the crack. Therefore, in this paper, the AE signal was saved by AE transducer during fatigue test. The noise level was reduced by a signal processing coded in Matlab and then the signal was evaluated and extracted by signal waveform type follow crack growth step. And the features, such as RMS, duration, Event, AE energy and so on, were calculated also.
김재구(JaeGu Kim),구동식(DongSik Gu),최병근(ByeongKeun Choi) 한국소음진동공학회 2011 한국소음진동공학회 학술대회논문집 Vol.2011 No.4
The acoustic emission (AE) technique is a well-known non-destructive test technique, both in research and for industrial applications. It is mainly used to monitor the onset of cracking processes in materials and components. Predicting and preventing the crack phenomenon has attracted the attention of many researchers and has continued to provide a large incentive for the use of condition monitoring techniques to detect the earliest stages of cracks. In this research, goal is in grasping features of AE signal caused by crack growth. The envelope analysis with discrete wavelet transform (DWT) is used to find the characteristic of AE signal. To estimate feature of divided into three by crack length, the time waveform and the power spectrum were generated by the raw signals and the transferred signal processed by envelope analysis with DWT.
Diagnosis of Cryogenic Pump-Motor Systems Using Vibration and Current Signature Analysis
ByeongKeun Choi,HakEun Kim,DongSik Gu,HyoJung Kim,HanEul Jeong 대한기계학회 2006 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.20 No.7
In general, to send out natural gas via a pipeline network across the nation in LNG terminal, high-pressure cryogenic pump supply highly compressed LNG to high-pressure vaporization facilities. The Number of cryogenic pumps determined the send-out amount in LNG receiving terminal. So it is main equipment at LNG production process and should be maintained on best conditions. In this paper, to find out the cause of high vibration at cryogenic pumps-motor system in LNG terminal, vibration spectrum analysis and motor current signature analysis have been performed together. Through the analysis, motor rotor bar problems are estimated by the vibration analysis and confirmed by the current analysis. So, it is demonstrated through the case study in this paper, how performing vibration analysis and current signature analysis together can reliable diagnosis rotor bar problems in pump-motor system.
정한얼(HanEol Joeng),김효중(HyoJung Kim),구동식(DongSik Gu),김학은(Hak Eun Kim),최병근(ByeongKeun Chio) 대한기계학회 2006 대한기계학회 춘추학술대회 Vol.2006 No.6
Recently, demands for the reduction of noise generated by transformers have been increasing. Accordingly the noise of transformer occasion displeasing to residents therefore the transformer needs to decrease of noise. One method of reduction such a noise is to build a free-standing enclosure of concrete and steel plates around the transformer. however, this method has some disadvantages, for example, a lage area is needed for equipment installation. In the paper, the vibration and noise effect which is transferred from reinforce channel to insulation panel generated by transformer have been identified for the several kinds of insulation panel and damping sheet experimentally.