• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.12 no.10
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• pp.758-765
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• 2002

KITECH and ODS performed a study of internal and external noise prediction of the Korean high speed prototype test train(HSR 350X). The object of this study was 3 kinds of cars, trailer car(TT2), motorized car(TMI ) and power car(TPI) and the predicted noise was for the two different driving speeds in free field and tunnel conditions. Data of carbody design and noise sources were delivered from manufactures. Some of noise sources which were not available in the project team, were chosen by experiences of ODS. Internal noise level of each car was predicted for two cases i.e, at 300 km/h and 350 km/h. In addition sound transmission path and dominant noise sources were also investigated for each section of the car, which is circular shell typed part of whole carbody. In case of TT2, the dominating sound transmission path is the (floor in terms of structure-borne noise and air-borne noise. The main noise sources are structure-borne noise from the yaw-damper and air-borne noise from the wheel/rail contact, whereas the dominating sound transmission path of TMI are floor and sidewall below the window in terms of structure-borne noise. The main noise sources of TMI are structure-borne noise from motor/gear unit and the yaw-damper in the free field, and air-borne noise from the wheel/rail contact and structure-borne noise from motor/gear unit in the tunnel. Through the external noise prediction for the KHST test train formation, the noise form the wheel/rail contact is estimated as one of the major sources. In addition, the noise specification of sub-component was proposed for managing each sub-surpplier to reach the KHST noise requirement. The specification provide the sound power of machinery part and transmission loss of component of carbody structure. The predicted noise level in each case exceeded the required limit. Through this study, the noise characteristics of the test train were investigated by simulation, and then the actual test will be performed in near future. Both measured and calculated data will be compared and further work for noise reduction will be continued.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2002.05a
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• pp.917-923
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• 2002

KITECH and ODS performed a study of internal and external noise prediction of the KHST test train. The object of this study was 3 kind of cars; trailer car(TT2), motorized car(TM1) and power car(TP1) and the predicted noise was calculated for the two different driving speeds in free field and tunnel conditions. Data of carbody design and noise sources were delivered from each manufactures. Some of noise sources which were not available in project team, were chosen by experiences of ODS. Internal noise level of each car were predicted for two cases i.e, at 300 km/h and 350 km/h. In addition sound transmission path and dominant noise sources were also investigated of each section of car, which is circular shell typed part of whole carbody. In case of TT2, the dominating sound transmission path is floor in terms or structure-borne noise and air-borne noise. The main noise sources are structure-borne noise from the yaw-damper and air-borne noise from the wheel/rail contact, whereas the dominating sound transmission path of TM1 are floor and sidewall below the window in terms of structure-borne noise. The main noise sources of TM1 are structure-borne noise from motor/gear unit and the yaw-damper in the free field, and air-borne noise from the wheel/rail contact and structure-borne noise from motor/gear unit in the tunnel. Through the external noise prediction for the KHST test train formation, the noise form the wheel/rail contact is estimated as one of the major sources. In addition, the noise specification of sub-component was proposed for managing each sub-surpplier to reach the KHST noise requirement. The specification provide the sound power of machinery part and transmission loss of component of carbody structure. The predicted noise level in each case exceeded the required limit. Through this study, the noise characteristics of the test train were investigated by simulation, and then the actual test will be performed in near future. Both measured and calculated data will be compared and further work for noise reduction will be continued.

• Proceedings of the KSR Conference
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• 2004.10a
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• pp.381-386
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• 2004

In order to develop a high speed train, various conditions have been considered. Internal noise level of cabins is an important one. In this study, The specification of the interior noise level for KHST(Korean High Speed Train) has been adopted the same level of KTX-spec. In this paper, the interior noise levels of KHST are measured and analysed through the speed and other conditions. According to the speed, the level of internal noise(driver's room(PC2), motorized trailer(TM1) and trailer car(TT2)) is compared. The results of measuring data show that the interior noise levels of KHST are good. And noise levels of this paper are useful in the decision of noise specification.

• Proceedings of the KSR Conference
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• 2004.06a
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• pp.652-657
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• 2004

Korean High Speed Train (KHST) designed to operate at 350km/h has been tested on KyungBu high speed line since it was developed in 2002. The specification of the interior noise level for high speed train in Korea has been adopted through the contract between KHRC and Korea TGV consortium, not a national specification. But it can not be adopted to KHST designed at 350km/h because this has involved up to 300Km/h. Therefor, in this paper, the interior noise level at 350km/h are predicted in passenger car using the results at 300Km/h and these results show that the KHST's interior noise levels are good up to 300Km/h but need to be reduced at 350Km/h in the view point of limit value at 300Km/h of the contract between KHRC and Korea TGV consortium. Also it proposed to make a national specification for the interior noise level to evaluate it in detail at 350Km/h.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2007.11a
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• pp.918-922
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• 2007

Aero-pulsation noise, generally caused by geometric asymmetry of a rotating device, is considerable source of annoyance in passenger cars using the turbocharged diesel engine. Main source of this noise is the compressor wheel in the turbocharger system, and can be reduced by after-treatment such as silencers, but which may increase the manufacturing cost. More effective solution is to improve the geometric symmetry over all, or to control the quality of components by sorting out inferior ones. The latter is more effective and reasonable than the former in view of manufacturing. So, an appropriate discrimination method should be needed to evaluate aero-pulsation noise level at the production line. In this paper, we introduce the accurate method which can measure the noise level of aeropulsation and also present its evaluation criteria. Besides verifying the reliability of a measurement system - a rig test system -, we analyze the correlation between the results from rig tests and those from vehicle tests. The gage R&R method is carried out to check the repeatability of measurements over 25 samples. From the result, we propose the standard specification which can discriminate inferior products from superior ones on the basis of aero-pulsation noise level.

• Proceedings of the KSR Conference
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• 2002.05a
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• pp.584-589
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• 2002

Recently, in various industrial field standardization and performance improvement are actively on going. Noise barrier is generally used to reduce railway noise. But the effectiveness of its use is low because of low level of technology development. In this basic study, test item and its specification are suggested for standardization of railway noise barrier.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 1997.04a
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• pp.362-369
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• 1997

In the case of a precision equipment, it requires a vibration free environment to provide its proper function. Especially, lithography and inspection devices, which have sub-nanometer class high accuracy and resolution, have come to necessity for producing more improved giga class semiconductor wafers. This high technology equipments require very strict environmental vibration standard in proportion to the accuracy of the manufacturing, inspecting devices. The vibration criteria of high sensitive equipment should be expressed in the form of 'exactness' and 'accuracy', because this is made basic data in the use of building structure design. This paper made a study on the specification of high sensitive equipment and proposed a contents of the specification.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2000.11a
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• pp.165-169
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• 2000

High level vibrationional environments induced while launching of spacecraft can damage sensitive equipment or payloads, unless the equipment is properly designed. This is a critical issue for KOMPSAT-2 which will carry a high resolution electro-optic camera and a sophisticated attitude and orbit control system. Thus careful consideration on the launch environment is required in the design stage of spacecraft. This requires generation of vibration specification for each component. This paper describes the generation process of vibrational specification for KOMPAT-2, which is designed and tested by Korean engineers.

• Journal of the Korea Society of Computer and Information
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• v.5 no.2
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• pp.115-120
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• 2000

This papers describes two low-noise amplifiers that use the Hewlett-Packard ATF-10236 low noise GaAs FET device, The actual measured performance of the amplifiers compares favorably to that predicted by the computer simulation(ADS) the noise figure of the 1575MHz amplifier was measured at 1.78dB which is lower that 2dB as specified. Measurement gam measured 33.0075dB which is within 35dB$\pm$0.5㏈ of the GPS specification. Network Analyzer(HP8510) is used to measure all the s-parameters and Noise Figure meter(HP8970B) is used to measure noise figure. As the result of experiment, gain, input VSWR, output VSWR is within the GPS specification sufficiently.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.12 no.2
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• pp.299-308
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• 2008

This paper proposes a new design specification-based band fault modelling technique that can test design specification in a time domain. The band fault model is defined and the conditions of band fault model are gained as normal operation regions are defined. And the conditions of band fault model are used in a 5.25GHz low noise amplifier, then 9 band fault models that can detect hard and parametric faults of active and passive devices are obtained.