• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 1997.10a
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• pp.210-215
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• 1997

Safety diagnosis on the driving system of electric train is performed using the vibration and noise signals of running railway train. Safety diagnosis is tried on the viewpoints of the appreciation of superannuation and the fault diagnosis of motor, reduction gear and boggie. The appreciation of superannuation is checked by the rms vibration levels of driving parts and the fault diagnosis is done by analyzing the frequencies of the vibration signals. The methods of measuring and analyzing the signals are decided on the basis of field 1-measured signals. The results shows that the vibration levels of each parts increase as the train goes older and each parts have their own frequency patterns of the vibration. As the results, the vibration and noise can be utilized successfully for the safety diagnosis of the driving part of electric train.

• Proceedings of the KIPE Conference
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• 2006.06a
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• pp.319-322
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• 2006

This paper deals with the HVDC system fault analysis and the sound noise analysis. In this paper, the reasons of the audible noise and vibration were analyzed, the fault waveform were analyzed using DTR (Digital Transient Recorder). Finally, using the fault current waveform and the vibration equation, the reason of crack of smoothing reactor support is estimated.

• Journal of KSNVE
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• v.7 no.5
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• pp.827-836
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• 1997

To suggest the standard of railroad noise and its measures and grasp its status 15 open sites of the Jungang. Taeback and Youngdong line in which the background noise level is very low and the railroad is at grade and 7 urban sites of the Kyungboo and Honam line were selected and the sound level which 373 trains passing through the former and 271 trains passing through the latter emitted was investigated. The community response of railroad noise was surveyed for apartment near wayside. Noise reduction of wall for apartment at the wayside was investigated. The prediction of electric train subway noise is derived for the environment impact assessment.

• 제어로봇시스템학회:학술대회논문집
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• 1997.10a
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• pp.1356-1359
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• 1997

There are various methods to detect the faulty electric facilities(esp, insulator) indirectly on power distribution lines at a certain distance apart. This paper describes the proto type equipment to detect a faulty insulator by receiving a electric discharge noises, which are generated with a periodicity of 120Hz.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2005.11a
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• pp.244-246
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• 2005

The Tonpiltz transducer is one of the essential elements in sonar application. The characteristics of transducer depend on the piezoelectric ceramics and mechanical elements such as head mass, tail mass, pre-stress rod and so on. One of the important characteristics is stable electric resistance for high power transmitting operation. This paper presents characteristics variation of the underwater acoustic transducer with material variation of electric decoupler.

• Journal of the Korean Society of Safety
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• v.26 no.5
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• pp.23-26
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• 2011

The aim of this paper is to evaluate noise characteristics of an electric power driven hammer. These investigation and analysis were made according to the ISO 1680/1 and MIL-STD 7410-1 and lead-wrapping experiment method that was used to identify the principal noise sources and analyze its noise. Hammer generates loud noise and it irritates and affects many people. Repeated exposures to loud noise can lead people to permanent hearing loss. Based on the contribution analysis, we confirm that the striker part is a major noise source and it has directional noise radiation pattern, which is left and right.

• Proceedings of the KIEE Conference
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• 2009.07a
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• pp.2021_2022
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• 2009

Partial discharges(PD) is a important factor to evaluate the insulation state in high voltage electric machinery. However, measuring PD under the circumstances of power plant is occasionally impossible due to the relatively high magnitude of noise which is emanated from the operating machinery. In some case, the instrument measuring PD can not even perform a calibration that initializes tools and enhance the accuracy. This paper presents that we devised a noise reduction method and demonstrated the usefulness in acquiring reliable PD signals. We attached a series of filter and transformer at the input of power source of the instruments which refrains high noise signals from incoming to the instruments. We experimented the efficiency of noise reduction applying the device into the Dangjin Power Plant and Factory. As a result of testing with the filter and transformer, we can easily calibrate the PD signal compared to the case without the device. Additionally, we can detect the small PD signal which was unperceived with a normal device.

• The Transactions of the Korean Institute of Electrical Engineers C
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• v.48 no.2
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• pp.117-126
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• 1999

The environmental impact of the KEPCO 765-kV transmission line was studied using a full scale test line in order to develop the design technology. Therefore this paper describes an environmental design summary of the audible noise, hum noise, wind noise, radio interference, TV interference and electric field measurement from the KEPRI 765-kV double circuit transmission test line with a bundle of $6-480mm^2$ conductors per phase. The analysis of the test results shows that 6-Rail and 6-Cardinal conductors bundle satisfy the audible noise criterion & TV interference under the stable rainy weather condition and the radio interference level under the fair weather. And the other items are also agreed with the design level criterion for KEPCO 765-kV transmission line.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.64 no.5
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• pp.812-816
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• 2015

Recently, various monitoring systems have been proposed to detect interaction performance between trains and infrastructure, as well as, various techniques to improve the accuracy and performance of such inspection equipment in high speeds. Especially, it is important to predict electric noise of high speed trains due to its effect on detection system accuracy. In this paper, we analyze various types of electrical noise in electric vehicles to improve the accuracy of the detection module of the inspection car. In detail, analysis of electric noise of high speed railway is performed as a function of speed based on field tests that were carried out by HEMU-430X (Highspeed Eletric Multiple Unit - 430 km/h eXperiment).

• Proceedings of the KSR Conference
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• 1999.05a
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• pp.185-191
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• 1999

This paper deals with a method to predict the noise level inside metro electric cars running a single-line tunnel at the speed of 80km per hour using ray tracing method, a kind of ray acoustics generally used for a high-frequency and air-born noise analysis. The interior of the car including a under-frame, seats, side doors, end doors, door-pockets, side panels, end panel, a roof panel and so on is modeled. And in order to describe the noise power coming inside, artificial noise sources are designated using sound transmission loss data of each section measured from simple tests and external noise level. The noise level inside the car is calculated and its properties are investigated. The results satisfy the criteria on noise level inside the car.