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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),이준서(J.S.Lee),차경옥(K.O.Cha) 한국자동차공학회 1999 한국자동차공학회 춘 추계 학술대회 논문집 Vol.1999 No.11_1
Setting the channel-switching phase of automobile control mufflers in low-speed region is effective measures to improve low-speed torque. A muffler sensing exhaust-gas pressure has been developed to solve this problem. This muffler reduces exhaust noise in a pair of tailpipes by generating interference through a reverse-phasing process. This reduces exhaust noise makes it possible to set the muffler's channel-switching phase in the low-speed region.<br/>
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/>
이준철(J.C Lee),이정원(J.W Lee),조정현(J.H Cho),김승호(S.H Kim) 한국정보과학회 2005 한국정보과학회 학술발표논문집 Vol.32 No.2
본 논문에서는 감시 시스템 내에서 검출된 객체에 대해 정확한 특징벡터를 추출하기 위한 그림자 제거(shadow casting)방법을 제안한다. 그림자에 의해 부정확한 특징벡터를 가지게 되는 객체는 동일한 객체임에도 불구하고 서로 다른 객체로 인식하는 잘못된 결과를 가져온다. 이러한 문제점을 해결하기 위해 추출된 객체의 경계선(edge)의 수직 히스토그램과 그림자의 방향성을 사용하여 그림자를 제거한다.
이준서(J.S.Lee),이해철(H.C.Lee),이민호(M.H.Lee),박명규(M.K.Park),차경옥(K.O.Cha) 한국자동차공학회 1998 한국자동차공학회 춘 추계 학술대회 논문집 Vol.1998 No.11_1
The pulsating pressure waves are composed of fundamental frequency and higher order harmonics in exhaust pipe of engines. The nonlinearity in exhaust pipe is caused by their interactions. The error which is between prediction and measurement is induced by the nonlinearity. We can not explain this phenomenon using linear acoustic theory which is existing theory. So power spectrum which was used in linear theory is not useful. Bispectrum and bicoherence functions which are a higher order spectrum are applicable to explain this phenomenon. This paper proposes a nonlinear effect of pulsating pressure waves. The phenomenon proposed here is identified by using of cross-higher order spectrum and quadratic Volterra model.<br/>