• The Journal of Society for e-Business Studies
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• v.23 no.2
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• pp.111-121
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• 2018

Many problems in rotating machinery such as aircraft engines, wind turbines and motors are caused by bearing defects. The abnormalities of the bearing can be detected by analyzing signal data such as vibration or noise, proper pre-processing through a few signal processing techniques is required to analyze their frequencies. In this paper, we introduce the condition monitoring method for diagnosing the failure of the rotating machines by analyzing the vibration signal of the bearing. From the collected signal data, the normal states are trained, and then normal or abnormal state data are classified based on the trained normal state. For preprocessing, a Hamming window is applied to eliminate leakage generated in this process, and the cepstrum analysis is performed to obtain the original signal of the signal data, called the formant. From the vibration data of the IMS bearing dataset, we have extracted 6 statistic indicators using the cepstral coefficients and showed that the application of the Mahalanobis distance classifier can monitor the bearing status and detect the failure in advance.

• Asia-pacific Journal of Multimedia Services Convergent with Art, Humanities, and Sociology
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• v.8 no.7
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• pp.475-484
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• 2018

The propulsion control device of an electric railway vehicle is a key main component corresponding to an engine of an automobile, and a device for controlling this is a device called a GDU (Gate Drive Unit). Also, when the frequency of failure of the propulsion control system was analyzed, the nonconformity ratio of GDU was the highest. GDU was not able to access core technologies due to the introduction of foreign products, and there were general problems with overall maintenance activities due to discontinuation of GDU of the manufacturer. The GDU has reached the end of its life with 23 to 14 years of long-term use.In order to solve these problems, this study was designed to identify the proper life span by analyzing compatible GDU's acquisition and failure, and to improve the existing system of maintenance focusing on health inspection. Maintenance of the components with a short life span compared to the entire service life is essential. Most foreign parts introduced at the beginning of the construction are not replaced due to technical problems or long-term operation. However, due to the characteristics of railway vehicles with a long life span of more than 25 years, it is necessary to maintain them for a long period of time. The study should be more concrete and empirical. The replacement type GDU of capacitors was able to easily measure the life of the capacitance by removing the capacitor modules, measure the life span of each unit test, and accurately perform preventive maintenance of the capacitor.

• Korean Journal of Psychosomatic Medicine
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• v.24 no.1
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• pp.43-53
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• 2016

Objectives : Somatic symptoms after the exposure of psychological trauma frequently developed. However, the somatic symptoms are not covered under the diagnostic criteria of posttraumatic stress disorder(PTSD) in detail, although they are often associated with social and occupational functioning and patient-doctor relationships. The aim of this article is to highlight the potential mechanisms, the common manifestations, and the treatment of the somatic symptoms. Methods : This article studied the somatic symptoms searched using academic search engines like PubMed, Scopus, Google Scholar, KoreaMed and KISS from the earliest available date of indexing to March 31, 2016. Results : The mechanism of somatic symptoms after the exposure was described as psychological and physiological aspects. Psychological mechanism consisted of psychodynamic theory, cognitive behavioral theory, and others. Physiological mechanism involved changes in neuroendocrine and immune system, autonomic nervous system and central nervous system. Somatization associated with psychological trauma manifested various health conditions on head and neck, chest, abdominal, musculoskeletal, and dermatological and immune system. Few studies described the standardization of treatment for the somatic symptoms. Conclusions : Clinicians and disaster behavioral health providers should think of the accompanying somatic symptoms during intervention of psychological trauma and PTSD. Further studies are needed on the somatic symptoms seen in psychological trauma and PTSD.