• Proceedings of the KSR Conference
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• 1999.11a
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• pp.542-549
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• 1999

The purpose of this study is to investigate stability of a high speed train and to propose optimal design using sensitivity analysis of suspension design parameters. A form of equations of motion in tangent track and curve track is obtained based on each creep force. Tangent track and curve track equations include lateral, rolling and yawing motions of wheel sets, bogies, and carbodies. Three track cases have been chosen to stability assesment of a high speed train analysis. Sensitivity equations are set up by directly differentiating the equations of motion. This study def'.led Stability performance index of a high speed train in tangent track and curve track. The relative magnitude of the effect of suspension parameters on the critical speed is computed, and by adjusting these parameters, the increase of the critical speed is achieved.

• Proceedings of the KSR Conference
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• 2008.11b
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• pp.1090-1095
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• 2008

Track geometry changes by traffic loads. The bigger the changes are, the worse the riding comfort and running stability of train. This is so-called track irregularity and is the most important quality parameters of ballasted track. To objectively assess track irregularity, track geometry should be able to be measured. Practically, railway companies use moving chord method, which determine versine values via a chord. The versine is the vertical distance to curve measured in the middle of the chord. This type of method measures only versine of track irregularity curve by transfer function from the characteristics of measuring device. In this report, review the characteristics of two types of measuring tools by comparing the measurements. The one is GRP-1000 system, optical surveying system with Total station and lazar prism trolley. This calculates track geometry by surveying absolute coordinates of two points each on both rail heads. The other is EM-120, measures versine with 10m of symmetrical chord length.

• Journal of the Korean Magnetics Society
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• v.7 no.2
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• pp.97-102
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• 1997

Off-track capability is used to determine the track pitch of hard disk drive system, and the off-track capability as a function of track pitch is called 747 curve. In this paper, 747 curves were simulated with computer. Side reading and recording parameters were obtained by magnetic field analysis using 3-D finite element method. Head read signal and noise voltages for calculation of signal to noise ratio (SNR) were obtained using reciprocity theorem. According to the 747 curves thus obtained, the off-track capability was increased as erase band width increased and as effective signal to noise ration $(SNR_{eff}}$ decreased. A simulated 747 curve and a measured 747 curve (using spin stand) of a planar silicon head with track width of 4.1 um were very similar, which indicated that the simulation was carried out properly.

• Proceedings of the KSR Conference
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• 2011.05a
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• pp.442-445
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• 2011

Concrete track on the new railway lines of the existing roads are built on high ground, or less than 400m radius of the sharp curve sectors will occur. sharp curve sectors the rail and wheel friction, stick-slip due to the band of 1,000Hz or squeal noise occurs from the increase in civil complaints about noise is a real situation. In this study, discussed in previous studies, noise measurements for each radius of concrete track and frequency analysis, followed by the radius of the curve in order to investigate vibration characteristics of urban railway sector sharp curve radius less than 400m and 400m ~ 1,000 m further to the point selected track components(rails, sleepers, ballast) according to the vibration measurements and analysis of the frequency characteristics and the results were derived.

• Proceedings of the KSR Conference
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• 2007.11a
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• pp.301-305
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• 2007

The performance of the railway bogie is classified into the stability and the steering performance. Testing for the bogie stability is conducted on the roller rig. But testing for the bogie steering performance on test facility is very difficult, so the testing for the vehicle curving performance is conducted on the real curve track. And it is desirable to test on the full scale test rig, but it caused many problems relating to test costs, test time. To overcome these problems, the small scale test rig is actively used in the field of bogie stability. Thus, in this paper, we have studied the scale track to test the bogie steering performance. For this, we designed the 1/5 scale test track equivalent to radius 200 curve and confirmed the validity of the testing for the bogie steering performance on the scale curve track through the testing using 1/5 scale bogie.

• Proceedings of the KSR Conference
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• 2011.10a
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• pp.69-74
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• 2011

In the curving detection method by using an accelerometer, the ride comfort in the first car is worse than one in the others due to spend the time to calculate the tilting command and drive the tilting mechanism after entering in the curve. In order to enhance the ride comfort in the first car, the preditive curve detection method which predicts the distance from a train to the starting point of curve by using the GPS, Tachometer, Ground balise and position DB for track. In this study, we predicted and evaluated the ride comfort for predictive curve detection method in transient curves according to the shape and dimension of transient curve and the various driving speed. Also, we predicted the improvement of the ride comfort for predictive curve detection method by comparing with the result of the ride comfort for predictive curve detection method and for curve detection method using an accelerometer in the short transient curve.

• Journal of the Korean Society for Railway
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• v.10 no.5
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• pp.613-618
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• 2007

The performance of the railway bogie is classified into the stability and the steering performance. Testing for the bogie stability is conducted on the roller rig, but testing for the bogie steering performance on test facility is very difficult, so the testing for the vehicle curving performance is conducted on the real curve track. Testing the railway bogie on the full scale test rig is desirable, but it caused many problems relating to test costs and test time. As a possible alternative to overcome these problems, a small scaled test rig is actively used in the field of bogie stability. Thus, in this paper, we have studied a scaled track to test the bogie steering performance. For this purpose, we designed the 1/5 scaled test track equivalent to radius 200 curve and confirmed the validity of the testing for the bogie steering performance on the sealed curve track through the testing using 1/5 scaled bogie.

• Proceedings of the KSR Conference
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• 2005.11a
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• pp.823-829
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• 2005

The extent of slack is correlative with the wheelbase of vehicle as well as the distance between the inner faces of flanges. Since the movable clearance of wheel flange is getting reduced in curved track, the vehicle is more difficult to negotiate the track. By this reason, a certain extent of slack is normally designed for curved track to allow the movable clearance corresponding to that of straight track. In case of some foreign railways,. the fixed extent of slack has been classified by the ranges of curve radius. In case of KNR, the slack is calculated by a formula for each case of curve radius and it therefore seems quite precise method. However, since there is a wide range of slack adjustment $(S'=0\~15mm)$ in calculation formula itself, too excessive or too little slack can be calculated. This study is to approach the technical review on slack calculation and to offer the reasonable slack design through the full-scale experiment at sharp curved track without slack.

• Proceedings of the KSR Conference
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• 2008.06a
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• pp.1647-1652
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• 2008

Track geometry consists of tangent and curved lines, which caused undesirable changes in initial track geometry by traffic loads. The bigger the changes are, the worse the riding comfort and running stability of train. This is so-called track irregularity and is the most important quality parameters of ballasted track. To be able to objectively assess track irregularity, track geometry should be able to be measured. Practically, railway companies use moving chord method, this method determine versine values via a chord. The versine is the vertical distance to curve measured in the middle of the chord. This type of method measures only versine of track irregularity curve by transfer function from specific property of measuring tool. In this report, review the characteristics of two types of measuring tools by comparing the measurements. The one is GRP-1000 system, optical surveying system with Total station and lazar prism trolly. This calculates track geometry by surveying absolute coordinates of two points each on both rail heads. The other is Trackmaster, measures versine with 2m of chord length.

• Proceedings of the KSR Conference
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• 2009.05a
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• pp.529-538
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• 2009

A trial run of locally-developed tilting train has been in process on Chungbuk line since the test vehicle was first produced. For the system stabilization, interface verification among the systems including track, structure, catenary and signaling system, not to mention the rolling stock, is very crucial. Therefore, in this study, the dynamic rail force of the tilting (Hanvit 200), high-speed (KTX) and general (Mugunghwa) vehicle caused by driving in transition curve track was measured. And, it compared the tilting response with the other by using the measured wheel load data in transition curve track, and then evaluated probability the range of wheel load fluctuation for the variable dynamic vertical and lateral wheel load. As a result, a range of wheel load by occured a change of cant from the high-speed and general vehicle which had fixed bogie structure was distributed throughout small deviation (${\Delta}8{\sim}13kN$). Otherwise, in case of the tilting train which was consisted of the pendulum bogie structure was distributed wide range about large deviation (${\Delta}25{\sim}28kN$) by changed of cant.