• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2003.05a
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• pp.549-554
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• 2003

Recently, the ride comfort problem becomes increasingly important because of today's needs for train speedup. The concept of ride comfort is equivocal. Generally, it is defined as the body vibration. The prototype of Korean high speed train (KHST), composed of two power cars, two motorized cars and three trailer cars, has been designed, fabricated and tested by the domestic researchers. In this paper, the ride comfort has been reviewed by the experimental method. The on-line test of KHST has been carried out up to 260km/h in the KTX line and proved that KHST has no problems from the viewpoint of the comfort ride at this speed. And the ride index lot KHST has been predicted at 300km/h and 350km/h by fitting curve.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.22 no.6
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• pp.535-541
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• 2012

The three-down one-up method which is commonly used in the field of psychophysics is employed in this study that is to reveal how much magnitude of vibration makes discomfort in passenger vehicle on idle condition. Thirteen taxi drivers were invited for subject of the experiment where they evaluated the controlled vibrations on rigid seat in terms of idle vibration on passenger vehicle at frequency range from 15 Hz to 40 Hz. As the result, vibration of 100~105 dB is marginal range to make discomfort on passenger seat. Frequency dependency of the discomfort was found at the frequency range, which is the higher frequency the lower discomfort with the same magnitude of vibration. The frequency dependency found here was compared with ISO 2631-1 that is more sensitive at the frequency range.

• Journal of the Korean Society for Railway
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• v.14 no.6
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• pp.495-500
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• 2011

In evaluating the ride comfort of railway vehicles, relationship between passenger's feeling and vibration characteristics is very important because human feeling is dependent on frequency spectrum of vibration. Therefore, the weighing curves in frequency domain are used to evaluate the ride comfort of railway vehicles. These curves have been defined in the Laplace transfer functions. It is necessary to convert the Laplace weighing function to the z weighing function in order to obtain the rms value in the time domain. In the present paper, we have applied Tustin's approximation to transform the Laplace weighing function to the z weighing and validated this method by reviewing the various cases.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.13 no.7
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• pp.539-547
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• 2003

The prototype of Korean high speed train(KHST), composed of two power cars, two motorized cais and three trailer cars, has been designed, fabricated and tested. In this paper. the body vibration has been reviewed from the viewpoint of the vehicle's safety, the ride comfort and the vibration limits for components and sub-assemblies mounted on the car-body using by analytical method and experimental method. The on-line test of KHST has been tarried out up to 260 ㎞/h in the KTX line and the results of the on-line test show that KHST has no problems in the vehicle's safety. the comfort ride and the vibration limits at this speed. And the characteristics of body vibrations has been Predicted at 300 ㎞/h and 350 ㎞/h by fitting curve about the measured acceleration signals.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2004.05a
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• pp.206-211
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• 2004

Recently, the ride comfort problem becomes increasingly important because of today's needs for train speedup. The concept of ride comfort is equivocal. Generally, it is defined as the body vibration. The commercial high-speed train must be run the compound line in Korea which is composed of high-speed line and conventional line. In this paper, the ride comfort has been reviewed by the various experimental methods when the high-speed train is operated on both lines. The results show that the high-speed train has no problems from the viewpoint of the comfort ride during the operation on both lines.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2003.11a
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• pp.1043-1047
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• 2003

Most of the measurement and the evaluation of hand-transmitted vibration have been performed by using a small size single axis accelerometer between the handle and the hand palm or a three axis accelerometer attached on an adapter outside the hand(indirect measurement). It is most desirable for the correct evaluation of hand-transmitted vibration form the power tool handle to measure the acceleration between the handle surface and the hand palm in the three axis(direct measurement) as recommended in ISO 5349-1. In the study three axes acceleration measurement device was developed of which the thickness was less than 7mm so that it can be placed between the handle and the palm without any inconvenience during the measurement. To verify the performance of the developed device, measured acceleration by the two methods, direct and indirect, were compared in the study.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2014.10a
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• pp.131-133
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• 2014

Vibration exposure of the KTX and ITX-saemaeulho on the Gyung-Bu line was evaluated and compared in terms of human health based on ISO 2631. RMS value of KTX was calculated as much lower than ITX-saemaeulho in all travel sections. When VDV result of the two trains drived return travel from Seoul to Busan in single day is compared on the health guidance caution zone of ISO 2631, vibration exposure of KTX is safer than ITX-saemaeulho which is marginally under the caution line.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.25 no.4
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• pp.266-274
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• 2015

Vibration exposure of domestic high speed trains(KTX and ITX-saemaeulho) to passenger traveling on the Gyung-Bu line was measured to evaluate health effect which is based on ISO 2631-1. The vibration exposure was compared with the frequency weighted root mean square(r.m.s.) and vibration dose value(VDV) of the two trains’ vibration. It is concluded that vibration exposure of the two train during round trip of Busan-Seoul in single day is evaluated to be safe for the passenger’s health according to the health guidance caution defined on ISO 2631-1. Futhermore KTX’s vibration exposure is found to be significantly lower than ITX-saemaeulho thanks to lower vibration magnitude as well as shorter trip time.

• Journal of Sensor Science and Technology
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• v.13 no.5
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• pp.369-377
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• 2004

Recently, the "ride comfort" problem becomes increasingly important because of today's needs for train speedup. The concept of term "ride comfort" is equivocal. Generally it is defined as the vehicle vibration. There are many studies on evaluation method of ride comfort for railway. But each of them recommends the different assessment method and the different guidance. In general, the evaluation methods defined in the standards, such as ISO 2631 and UIC 513R, and Ride Index suggested by Sperling, have been used in the railroad. But, only one or two methods of these can be evaluated by using the commercial ride comfort measuring system. Therefore, it is necessary to develop the new ride comfort measuring system for railway with multi-function. In this paper, the generalization of "ride comfort" and the design and verification of new ride comfort measuring system for railway with multi-function have been described and the application examples has been introduced.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.14 no.10
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• pp.999-1006
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• 2004

Recently, the ride comfort problem becomes increasingly important because of today's needs for train speedup. The railway has the track irregularities which cause vibrations, such as rail joints, turnout, level crossing, transition corves and super-elevation ramps, and variations in the track level(z-axis) and the gauge(y-axis). In Korea, the service run of the high speed train has been made since the 1st of April, 2004. The commercial high-speed trains must be run on the compound lines which are composed of high-speed line and conventional line. The high speed lines in both Kyoungbu line and Honam line have 57.5％ and 33.8％, respectively In this Paper, the ride comfort has been reviewed by the various experimental methods when the high-speed trains are operated on both Kyoungbu line and Honam line. The results show that the high-speed train has no problems from the viewpoint of the comfort ride during the operation on the high speed line and conventional line.