• Proceedings of the KIEE Conference
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• 2001.07b
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• pp.1245-1247
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• 2001

This paper discusses that the maintenance of the propulsion equipment in railway rolling stock. Condition monitoring of railway equipment is the need for integration of remote condition monitoring with maintenance management strategies. The paper outlines research leading to the design and development of a prototype control and monitoring system for propulsion equipment.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2009.04a
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• pp.49-59
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• 2009

Vibrations of the tower structures of 750kW and 6kW wind turbines(WT) are investigated by measurement and analysis. Acceleration responses of the WT towers under various operation condition are monitored in real time by the remote monitoring system using LabVIEW. Using the monitoring system, resonance condition of the tower structures is diagnosed with the wind speed data within the operating speed range. To predict the tower resonance frequency, 750 kW tower is modeled as an equivalent beam with a lumped mass and Rayleigh energy method is applied. For 6 kW WT, Rayleigh-Ritz analysis is carried out on the tower-cable coupled system. Calculated tower bending frequency is in good agreement with the measured value. Using the analysis model, parametric study is available in order to prevent the severe resonance.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2010.06a
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• pp.116-116
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• 2010

This paper introduces an comprehensive monitoring and management program for implementation of a real-time monitoring system that monitors condition of urban railway AC/DC transformers, disconnecting switches, circuit breakers, regulators, and GIS (Gas Insulated Switchgear). Especially, the system is applied to diagnose the overall condition of urban railway substations by sending acquired data through an OPC server to a database, effectively storing and monitoring conditions simultaneously. The above system is a management based system and is also applicable to small-scale systems.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2008.04a
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• pp.562-565
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• 2008

Measuring system for piezo inkjet droplet and ink jetting status was developed. In order to measure the jetting performance, two different approaches have been used. One is to use the self-sensing capability of the piezo actuator in the printhead. The other is to use the droplet image from a CCD camera. The software as well as hardware using two approaches was developed. The self-sensing signal as well as meniscus motion was shown to be useful in monitoring jetting conditions. Furthermore, ink properties such as viscosity and speed of sound, which is related to jetting performance, can be understood.

• Journal of Advanced Marine Engineering and Technology
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• v.28 no.2
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• pp.285-291
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• 2004

Early detection of an internal malfunction of machinery plays a very important part in all condition monitoring programs. Sensors to detect amplitude. velocity and acceleration are widely used in vibration detection and control. Piezoceramic materials are largely used in sensors and actuators for vibration monitoring and control due to their relatively large output from an induced strain and their arguable self powering characteristics. In this paper a cheap and yet reliable sensors/actuators were developed to detect vibration. The results show that low cost PZT can be designed for optimum detection of bearing vibration. This paper presents the experimental results of a number of piezoceramics characteristics in terms of resonant frequencies and variation of PZT constants with temperature.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.15 no.4
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• pp.134-140
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• 2016

Main Spindle System has effect on performance of machine tools and working quality as well as is required of high reliability. Especially, it takes great importance in producing automobiles which includes a large number of working processes. However, main spindle unit in Machine tools are often cases where damage occurs do not meet the design life due to driving in harsh environments. This is when excessive maintenance and repair of machine tools or for damage stability has resulted in huge economic losses. Therefore, this studying propose a method of accelerated life test for diagnosing and prognosis the state of life assessment main spindle system. Time status monitoring of diagnostic data - through the analysis of the frequency band signals were carried out inside the main spindle bearing condition monitoring and fault diagnosis.

• Proceedings of the KIEE Conference
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• 2002.07c
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• pp.1701-1703
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• 2002

This paper introduces a on-line monitoring system for insulation diagnosis of high-voltage motor stator windings. This system monitors the insulation condition of the stator winding with sensor, coupling capacitor. Partial discharge (PD) signals are able to be continuously measured and digitalized with a Peak-hold A/D converter to build the database of the high-voltage motor's insulation condition. This system can communicate with the central monitoring system via RS-485 This paper introduces an economic solution for data acquisition of partial discharges.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1994.10a
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• pp.125-130
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• 1994

Recently,manufacturing work been transformed to small acale production from with various items to act up to user's expectation from mass production with a little items required in the past. The FMS using NC type mother machinaries has been applied actively also in domestic manufacturing line to meet thus tendancy, but there are many machining troubles occured in work process not be settled yet. Nowdays high efficiency has been required no less than high precision in grinding work for the improvement of productivity. In this study, to represent more advanced FMS can be adapted to thus situation In-process type monitoring method using AE and Current sensors is suggested to investigatethe machining condition in grinding process. As results from this experimental study, is is recoqnized well that grinding conditions and dressing point of in time can be estimated effectively using monitoring method suggested. Furthermore, surface shape of grinding wheel on voluntary point of in time can be predicted indirectly through the observation and comparison of AE signal waveform obtained as performance of continuous dressing work.

• Journal of Power System Engineering
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• v.11 no.1
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• pp.39-44
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• 2007

The purpose of this study is to verify availability of the acoustic emission in-situ monitoring method to the internal leak and operating conditions of the major valves at nuclear power plants. In this study, acoustic emission tests are performed when the pressurized temperature water and steam flowed through glove valve(main steam dump valve) and check valve(main steam outlet pump check valve) on the normal size of 12 and 18". The valve internal leak monitoring system for practical field was designed. The acoustic emission method was applied to the valves at the site, and the background noise was measured for the abnormal plant condition. To improve the reliability, a judgment of leak on the system was used various factors which are AE parameters, trend analysis, frequency analysis, voltage analysis and amplitude analysis of acoustic signal emitted from the valve operating condition internal leak.

• Proceedings of the KSR Conference
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• 2009.05a
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• pp.291-295
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• 2009

We did the blooth module test as a pre-test of wireless sensor monitoring system, which for the improving of on-condition maintenance reliability, on the train. In this test, we examined the communication environment of wireless sensor monitoring system by the acceleration date and frequency date in the real train structure during the operation. Also based on this results, we did the experimental verification of the sensor power system which use piezoelectric energy conversion technology by the theoretical modeling for the applying on the train on-condition maintenance.