• Proceedings of the KSR Conference
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• 2010.06a
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• pp.310-314
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• 2010

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 in Korea use normal distribution as probability distribution of track irregularity. But some countries use non-normal distribution according to their own track recording system. In this report, reviewed probability distribution of Kyung-Bu high-speed line and tested normality.

• Proceedings of the KSR Conference
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• 2007.11a
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• pp.1590-1593
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• 2007

Establishing the remote monitoring system of the moving test train is the important issue for the railway systems that provide comfort travel to the passengers. But it is not easy to transmit train's test data to remote site because the train runs tunnels. This paper represent the development results of Hanvit 350 remote monitoring system using wireless data communication system which is installed in the test train. This system can provide both correct positions of unstable track and train's running status such as speed, kilopost and acceleration.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2000.06a
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• pp.894-899
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• 2000

Optimization of 26 design variables selected from suspension characteristics for Korean High Speed Train (KHST) is performed according to the minimization of 58 responses which represent running safety and ride comfort for KHST and analyzed by using the each response surface model from stochastic design experiments. Sensitivity of design variables is also analyzed through the response surface model which ineffective design prameters to the performance index are screened by using stepwise regression method. The response surface models are used for optimizing design variables through simplex algorism. Values of performance index simulated by optimized design parameters are totally lower than those by initial design parameters. It shows that this method is effective for optimizing multi-design variables to multi-object function.

• International journal of advanced smart convergence
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• v.1 no.1
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• pp.48-51
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• 2012

The conventional method for filtering force plate data, low-pass filtering, does not always give accurate results when applied to force data from a custom-made, instrumented treadmill. Therefore, this study compares low-pass filtered data to the same data passed through a wavelet filter. We collected data with the treadmill running. However these include motor noise with ground reaction force at two force plates. We found that he proposed wavelet method eliminated motor noise to result in more accurate force plate data than the conventional low-pass filter, particularly at high speed motor operation. In this study we suggested the convolution wavelet (CNW) which was compared to that of a low-pass filter. The CNW showed better performance as compared to band-pass filtering particularly for low signal-to-noise ratios, and a lower computational load.

• Proceedings of the KIEE Conference
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• 1995.11a
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• pp.519-522
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• 1995

ATS Systems are activated against the over-running and the crashes between trains. Up to now, ATS Systems have been constituted analog systems adopting the changed frequency method or amplitude modulation, which is impossible to give any essential informations. In this paper, it is dealt with digital ATS Systems which are replaced the former ATS Systems in the advanced nation of railways. Especially, this paper shows the possibility of any developments for the digital ATS Systems by the experiment of digital ATS Systems by Frequency Shift Keying method.

• Journal of Advanced Marine Engineering and Technology
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• v.18 no.2
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• pp.75-82
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• 1994

The existence of peroodic impulse noises in distribution line carrier (DLC) communication system is known to be the most serious obstacle for improving DLC communication quality in reliability and capacity. From the spectral points, impulse noises can be divided into baseband type and modulation type the noise width of whichs are much different each other. With each nose type, this study presents the basic characteristics in relation to what they originate from and how their spectrum properties are revealed. The baseband type impulse noise is normally caused from thyristor circuit running with low switching speed and the modulation type noise from the circuit of switching power supply. The base wave of modulation noise is shown to be the pulsuatic charging current to primary condenser in switching power circuit. The study result indicates also that placing the DLC carrier frequency away the band predominated by modulated noise especially from RCC type switching power circuit is very important in DLC design.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 1999.10a
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• pp.440-445
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• 1999

One of the important technical issues is how to decrease thermal expansion of ballscrew in proportion to the increase of machining speed. When measuring force of stretch of ballscrew, since not only actual expansion and the value of bending have to be considered, it's impossible to definite the exact value of expansion. In addition, support bearings of ballscrew gain considerable force in axial direction. It also generates thermal expansion on the ballscrew, and deteriorates the bearings. In conclusion, it's impossible to give the pretension enough to absorb the all elongation due to thermal expansion generated during machine running. If gave, bed, column and saddle are all bent to change machine accuracy, and the pretension of support bearing of ballscrew in machine tool.

• Transactions of the Korean Society of Machine Tool Engineers
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• v.11 no.3
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• pp.51-56
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• 2002

In order to achieve high precision machine tools, Performance enhancement of feed drive systems is required. One of the important technical issues is how to decrease thermal expansion of ball screw in proportion to the increase of machining speed. When measuring force of stretch of ball screw, since not only actual expansion and the value of bending have to be considered, it is impossible to define the exact value of expansion. In addition, support bearings of ball screw gain considerable force in axial direction. It also generates thermal expansion on the ball screw, and deteriorates the performances of the hearings. In conclusion, it is impossible to give the pretension enough to absorb all the elongation due to thermal expansion generated during machine is running. If given bed column and saddle are all bent to chance machine accuracy, and the support bearings of ball screw is damaged.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.32 no.12
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• pp.1096-1101
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• 2008

When we design a controller for the active magnetic bearings that support a large rotor, it is important to have an accurate model of the rotor. For the case of the flywheel that is used to store energy, an accurate rotor model is especially important because the dynamics change with respect to the running speed due to gyroscopic effects. In this paper, we present a procedure of obtaining an accurate rotor model of a large flywheel energy storage system using finite-element method. The model can predict the first and the second bending mode which match well with the experimental results obtained from a prototype flywheel energy storage system.

• Journal of the Korea Computer Industry Society
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• v.2 no.9
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• pp.1239-1244
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• 2001

The Virtual Interface Architecture (VIA) is usually suggested as a new standard high-performance communication of the cluster systems. However the VIA specification aims for platform independence, the current Intel VI Provider Library (VIPL) design favors systems with Intel architecture processors running the Windows operating system (OS). This paper aims for clarifying the guesstion problem of VIA and VIPL in the newtrul time of CPU Architecture and OS further more, It suggests the solution aiming the communication in the other CPU or OS