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[진동·소음부문] 회전요소 베어링 상황감시를 위한 음향-진동 신호의 고차 통계해석
이해철(H.C.Lee),이준서(J.S.Lee),차경옥(K.O.Cha) 한국자동차공학회 1999 한국자동차공학회 춘 추계 학술대회 논문집 Vol.- No.-
This paper present a study on the application of sound pressure and vibration signals to detect the presence of defects in a rolling element bearing using a statistical analysis method. The well established statistical parameters such as the crest factor and the distribution of moments including kurtosis and skewless are utilized in this study. In addition. other statistical parameters derived from the beta distribution function are also used. A comparison study on the performance of the different types of parameter used is also performed. The statistical analysis is used because of its simplicity and quick computation. Under ideal conditions. the statistical method can be used to identify the different types of defect present in the bearing. In addition. the results also reveal that there is no significant advantages in using the beta function parameters when compared to using kurtosis and the crest factor for detecting and identifying defects in rolling element bearings from both sound and vibration signals.
이해철(H.C.Lee),이민호(M.H.Lee),이준서(J.S.Lee),한경(K.Han),양진승(J.S.Yang),차경옥(K.O.Cha) 한국자동차공학회 1998 한국자동차공학회 춘 추계 학술대회 논문집 Vol.1998 No.5_1
In automobile exhaust system, internal pulsating pressure and shell vibration greatly affect the exhaust noise and the surface radiated noise. This noise is emitted from the tailpipe outlet and the muffler outer wall due to the pulsation of the exhaust gas pressure. This paper describes an analytical study of these characteristics as influenced by exhaust system structure. An exhaust system simulator was used for generating the pressure pulsation. The relationship between pulsating pressure and exhaust noise was analyzed. The relationship between shell vibration and surface radiated noise was also identified by finding FRF.<br/>
EMI 센싱 기법을 이용한 잔골재 혼합비에 따른 모르타르의 응결특성
이준철 ( Lee Jun-cheol ) 한국건축시공학회 2022 한국건축시공학회 학술발표대회 논문집 Vol.22 No.1
The electro-mechanical impedance(EMI) behavior of piezoelectric sensor embedded in cement mortar was investigated to assess the setting times. EMI signal was continuously measured for 12 hours by the PZT sensor embedded in cement mortar with different ratio of sand. As a result, the setting times by the penetration resistance test were accelerated as the sand ratio increased. However, the setting times by EMI sensing technique were delayed as the sand ratio increased.
이준철 ( Lee¸ Jun-cheol ) 한국건축시공학회 2021 한국건축시공학회 학술발표대회 논문집 Vol.21 No.2
In this study, the setting times of concrete was evaluated using the electro-mechanical (EMI) behavior of piezoelectric sensor embedded in the concrete. Penetration resistance test was also performed to compare with EMI sensing technique. As a result, the setting times of concrete can be measured more effectively than penetration resistance test through the EMI sensing technique using the piezoelectric sensor.