• Journal of Welding and Joining
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• v.12 no.2
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• pp.97-107
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• 1994

Both in-process quality control and high reliability of the weld is one of the major concerns in applying friction welding to the economical and qualified mass-production. No reliable nondestructive monitoring method is available at present to determine the real-time evaluation of automatic production quality control for friction welding of special hydraulic valve spool of 16mm in diameter. This paper, so that, presents the experimental examinations and statistical quantitative analysis of the correlation between the initial cumulative counts of acoustic emission(AE) occurring during plastic deformation periods of the welding and the tensile strength and other properties of the welded joints of $\phi16$ valve spool as well as the various welding variables, as a new approach which attempts finally to develop real-time quality monitoring system for friction welding.

• Proceedings of the Korea Information Processing Society Conference
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• 2012.11a
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• pp.20-23
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• 2012

최근 해양자원의 중요성이 대두됨에 따라, 해양환경을 모니터링 하기 위해 Underwater Acoustic Sensor Networks(UW-ASN)가 활발히 연구되고 있다. UW-ASN 는 해양환경에 대한 데이터를 Sensing, gathering 하고 이를 Monitoring Center로 delivering 하는 Mission 을 수행한다. 이 논문에서는 해양에서 수집한 데이터를 수질 자동 측정망(TMS: Tele Monitoring System)에 전송하기 위해, 음파통신을 통해 수신된 해양 데이터를 수질 자동 측정망의 규격에 맞는 데이터로 변환시키고 CDMA 통신을 통해 가상의 TMS에 전송하는 Gateway 구현을 제안한다.

• Smart Structures and Systems
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• v.8 no.3
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• pp.321-341
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• 2011

Acoustic emission (AE) monitoring was conducted for mortar specimens under three types of static loading patterns (cubic-splitting, direct-shear and pull-out). Each of the applied loading patterns was expected to produce a particular fracture process. Subsequently, the AEs generated by various fracture or damage processes carried specific information on temporal micro-crack behaviors of concrete for post analysis, which was represented in the form of detected AE signal characteristics. Among various available characteristics of acquired AE signals, frequency content was of great interest. In this study, cement-based piezoelectric sensor (as AE transducer) and home-programmed DEcLIN monitoring system were utilized for AE monitoring on mortar. The cement-based piezoelectric sensor demonstrated enhanced sensitivity and broad frequency domain response range after being embedded into mortar specimens. This broad band characteristic of cement-based piezoelectric sensor in frequency domain response benefited the analysis of frequency content of AE. Various evaluation methods were introduced and employed to clarify the variation characteristics of AE frequency content in each test. It was found that the variation behaviors of AE frequency content exhibited a close relationship with the applied loading processes during the tests.

• Animal cells and systems
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• v.16 no.3
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• pp.260-267
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• 2012

Calling behavior is often used to infer breeding patterns in anurans. We studied the seasonal and diel calling activities of anuran species in a wetland in central Korea to determine the calling season and to evaluate the effects of abiotic factors on male calling. Acoustic monitoring was used in which frog calls were recorded for a full day, once a week, throughout an entire year. Using acoustic monitoring, we identified three frog species in the study site. Males of Rana dybowskii called in late winter and early spring; we thus classified this species as a winter/spring caller. The results of binary logistic regression showed that temperature, relative humidity, and 1-day lag rainfall were significant factors for male calling in R. dybowskii. Temperature and relative humidity were important factors for the calling activity of R. nigromaculata, whereas 24-h rainfall and 1-day lag rainfall were not significant. Thus, we determined R. nigromaculata to be a summer caller independent of weather. In Hyla japonica, relative humidity, 24-h rainfall, and 1- day lag rainfall were significant for male calling, suggesting that this species is a summer caller dependent on local rain.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2008.06a
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• pp.437-438
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• 2008

• Journal of Korean Neurosurgical Society
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• v.60 no.2
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• pp.165-173
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• 2017

Objective : To explore and analyze the influencing factors of facial nerve function retainment after microsurgery resection of acoustic neurinoma. Methods : Retrospective analysis of our hospital 105 acoustic neuroma cases from October, 2006 to January 2012, in the group all patients were treated with suboccipital sigmoid sinus approach to acoustic neuroma microsurgery resection. We adopted researching individual patient data, outpatient review and telephone followed up and the House-Brackmann grading system to evaluate and analyze the facial nerve function. Results : Among 105 patients in this study group, complete surgical resection rate was 80.9% (85/105), subtotal resection rate was 14.3% (15/105), and partial resection rate 4.8% (5/105). The rate of facial nerve retainment on neuroanatomy was 95.3% (100/105) and the mortality rate was 2.1% (2/105). Facial nerve function when the patient is discharged from the hospital, also known as immediate facial nerve function which was graded in House-Brackmann : excellent facial nerve function (House-Brackmann I-II level) cases accounted for 75.2% (79/105), facial nerve function III-IV level cases accounted for 22.9% (24/105), and V-VI cases accounted for 1.9% (2/105). Patients were followed up for more than one year, with excellent facial nerve function retention rate (H-B I-II level) was 74.4% (58/78). Conclusion : Acoustic neuroma patients after surgery, the long-term (${\geq}1year$) facial nerve function excellent retaining rate was closely related with surgical proficiency, post-operative immediate facial nerve function, diameter of tumor and whether to use electrophysiological monitoring techniques; while there was no significant correlation with the patient's age, surgical approach, whether to stripping the internal auditory canal, whether there was cystic degeneration, tumor recurrence, whether to merge with obstructive hydrocephalus and the length of the duration of symptoms.

• Journal of the Korean Society of Safety
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• v.16 no.2
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• pp.22-26
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• 2001

The machining process on be considered as a planned interaction of the workpiece, the tool and the machine tool. In an unmanned situation, the results of this interaction are to be continuously monitored so that any changes in the machining environment on be sensed to corrective actions. In order to design the process monitoring system for unmanned manufacturing, the identification of chip formation is proposed. The system proposes the method of using acoustic emission(AE) signal analysis to identify the chip formation during cutting.

• Proceedings of the KSME Conference
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• 2004.11a
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• pp.1733-1739
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• 2004

The objective this study is to estimate the feasibility of acoustic emission method for the internal leak from the valves in nuclear power plants. From the experimental results, it was suggested that the acoustic emission method for monitoring of leak was feasible. When the background levels are higher than the acoustic signals from leak, we can detect the leak analyzing the spectrum of the remainders which take the background noise from the acoustic signals.

• Proceedings of the KSME Conference
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• 2004.04a
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• pp.284-289
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• 2004

The objective this study is to estimate the feasibility of acoustic emission method for the internal leak from the valves in nuclear power plants. From the experimental results, it was suggested that the acoustic emission method for monitoring of leak was feasible. When the background levels are higher than the acoustic signals from leak, we can detect the leak analyzing the spectrum of the remainders which take the background noise from the acoustic signals.

• Journal of the Korean Society for Nondestructive Testing
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• v.11 no.2
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• pp.15-21
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• 1991

A wireless acoustic emission (AE) system has been developed for continuous monitoring of rotating structures such as turbine rotors. The cable between preamplifier and signal processing unit of a conventional AE system was replaced by the frequency modulated telemetry. The detected signals were modulated and transmitted as an RF signals by the transmitting module, then received and demodulated by the receiving module. The distance between the transmitting and the receiving antennas could be separated up to 10cm within a reasonable signal-to-noise ratio. The simulated AE signals generated by pencil lead breaks from rotating structures were successfully detected using the developed wireless AE monitoring system.