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Development of a diagnostic system using LPC/cepstrum analysis in machine vibration
Monica Chamay,오세도,김영진 대한기계학회 2013 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.27 No.9
Based on the linear predictive coding (LPC) and cepstrum analysis coefficients (LPC/Cepstrum), the implementation of LPC procedure to detect faults in engine assembly line diagnostics systems is proposed. In addition, with the purpose to gain more accurate results in the implementation of LPC procedure instead the use of Euclidean distance, Mahalanobis distance is applied. In order to prove the effectiveness of the procedure, we retrieved data sets obtained from diesel engines under normal and abnormal conditions with different RPMs. During experiments, it was possible to detect the system status and it also was proved that the Mahalanobis distance overcomes the limitations of Euclidean distance where the statistical distribution of the variables are taken into account. In this way, we achieved a clear and accurate diagnosis of the system even when the differences between system status were not possible to detect through conventional methods. It was proved that the consistent patterns of each system status can be established and also possible to determine the system status successfully. The differences and advantages of LPC/Cepstrum approach compared with common analysis are discussed in this paper.
Mónica Chamay,오세도,김영진 대한기계학회 2014 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.28 No.9
Diverse techniques have been developed for dimension reduction, especially to facilitate the implementation of artificial neural networks(ANNs). For ANNs, the training process can become very complex and demand a great deal of hardware resources, making priordimension reduction very important; accordingly, this research proposes a new algorithm to increase the degree of dimension reduction. A new procedure is applied to extract important meaningful non-parametric characteristics from the data. The data in this research wasobtained from accelerometers installed in a wind power machine and processed using a linear predictive coefficient/cepstrum coefficientsprocedure. The procedure consists of the extraction of linear predictive coefficients from the signal data, and subsequent extraction of sixfeatures from those coefficients, thereby reducing the amount of data to process and enabling processing of that information using neuralnetworks. The features employed were selected carefully based on the error obtained from a neural network implementation. As a resultof the implementation was shown to reduce the data to only six input variables for the ANN, thereby enabling the ANN to achieve a verylow rate of classification error and training time consuming.
Khaled Elfert,Salomon Chamay,Lamin Dos Santos,Mouhand Mohamed,Azizullah Beran,Fouad Jaber,Hazem Abosheaishaa,Suresh Nayudu,Sammy Ho 대한소화기내시경학회 2024 Clinical Endoscopy Vol.57 No.1
Background/Aims: The pancreatic pseudocyst (PP) is a type of fluid collection that typically develops as a delayed complication of acute pancreatitis. Drainage is indicated for symptomatic patients and/or associated complications, such as infection and bleeding. Drainage modalities include percutaneous, endoscopic, laparoscopic, and open drainage. This study aimed to assess trends in the utilization of different drainage modalities for treating PP from 2016 to 2020. The trends in mortality, mean length of hospital stay, and mean hospitalization costs were also assessed. Methods: The National Inpatient Sample database was used to obtain data. The variables were generated using International Classification of Diseases-10 diagnostic and procedural codes. Results: Endoscopic drainage was the most commonly used drainage modality in 2018–2020, with an increasing trend over time (385 procedures in 2018 to 515 in 2020; p=0.003). This is associated with a decrease in the use of other drainage modalities. A decrease in the hospitalization cost for PP requiring drainage was also noted (29,318 United States dollar [USD] in 2016 to 18,087 USD in 2020, p<0.001). Conclusions: Endoscopic drainage is becoming the most commonly used modality for the treatment of PP in hospitals located in the US. This new trend is associated with decreasing hospitalization costs.