• Proceedings of the KSR Conference
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• 2011.05a
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• pp.427-434
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• 2011

This paper is focused on application of recursive least squares method to estimate rail irregularities from the acceleration measurement on an axle-box or a bogie for the rail condition monitoring with in-service high-speed trains. Generally, the rail condition was monitored by a special railway inspection vehicle but the monitoring method needs an expensive measurement system. A monitoring method using accelerometers on an axle-box or a bogie was already proposed in the previous study, and the displacement was successfully estimated from the acceleration data by using Kalman and frequency selective band-pass filters. However, it was found that the displacement included not only the rail irregularities but also phase delay of the applied filters, and effect of suspension of the bogie and conicity of the wheel. To identify the rail irregularities from the estimated displacement, a compensation filter method is proposed. The compensation filters are derived by using recursive least squares method with the estimated displacement as input and the measured rail irregularity as output. The estimated rail irregularities are compared with the true rail irregularity data from the rail inspection system. From the comparison, the proposed method is a useful tool for the measurement of lateral and vertical rail irregularity.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.59 no.2
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• pp.355-358
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• 2010

As CMOS technology continues to scale down, signal processing is favorably done in the digital domain, which requires Analog-to-Digital (A/D) Converter to be integrated on-chip. This paper presents a design methodology of 12-bit 1-MS/s Rail-to-Rail fully differential SAR ADC using Deep N-well Switch based on binary search algorithm. Proposed A/D Converter has the following architecture and techniques. Firstly, chip size and power consumption is reduced due to split capacitor array architecture and charge recycling method. Secondly, fully differential architecture is used to reduce noise between the digital part and converters. Finally, to reduce the mismatch effect and noise error, the circuit is designed to be available for Rail-to-Rail input range using simple Deep N-well switch. The A/D Converter fabricated in a TSMC 0.18um 1P6M CMOS technology and has a Signal-to-Noise-and-Distortion-Ratio(SNDR) of 69 dB and Free-Dynamic-Range (SFDR) of 73 dB. The occupied active area is $0.6mm^2$.

• Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
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• 2006.11a
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• pp.294-297
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• 2006

The rail clamp is the device to prevent the crane slips along a rail from the wind blast as well as to locate a container crane in the set position during an operating mode. In this study we conduct the research for determining the proper position of supporter to prevent the overload applied to the rail clamp with respect to the wedge angle in the wedge type rail clamp. The friction force between the jaw pad and the rail to prevent that the crane slips along a rail, when the wind blows, is generated fly the rail-directional wind load. Accordingly the proper position of the supporter to prevent the overload is determined fly analyzing the forces applied to the rail clamp in the wedge working stage. In order to analyze the effect of the wedge angle on the position of supporter, 5-kinds of wedge angles, such as 2, 4, 6, 8, $10^{\circ}$, were adapted as the design parameter, and the wind speed of 40m/s was adapted as the design wind speed criteria.

• Proceedings of the KSR Conference
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• 2011.05a
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• pp.1142-1147
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• 2011

The rail cant produces a wider bearing area between the wheel and the rail by moving the wheel-rail contact area away from the gauge towards the centre of the railhead, thus improving the wear pattern of the railhead and wheel treads. It is essential to keep the rail cant within the allowable range to ensure optimum track geometry. Neglecting the rail cant geometrical parameters in a track quality evaluation can cause safety of railway vehicle and serviceability problems. In this paper, we examined the effect of the rail cant in general geometry state of the railway track using VI-Rail and analyzed running safety when the railway vehicle passing through curves depending on change of the rail cant and running speed.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2002.11b
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• pp.328-333
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• 2002

When vehicle travelling along the track which has irregularity such as vertical profile, dynamic forces arise at the Wheel/Rail contact patch by wheel/rail interaction. In particular short wavelength irregularities on dipped joint and small stiffness of connecting rail bring about intense wheel/rail dynamic effects at higher speed. In the paper, a new model for dipped joint rail is developed to study dynamic behavior of track. A cusp behavior on dipped joint was defined by its amplitude and decay factor, which was presented by FRA track classes. The result of case study are presented, which show wheel rail contact force in each track classes, train operation speed and bending flexible rigidity ratio of fishplates which are connecting the rail.

• Proceedings of the KSR Conference
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• 2007.11a
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• pp.1451-1455
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• 2007

MAGLEV(Magnetic Levitation) with Middle-low speed be classified as a kind of LRT(Light Rail Transit) in KOREA. Also this vehicle has adopted LIM propulsion method. The MAGLEV has adopted LIM type in operational or developing model in the world. The power rail of LIM is very similar with the 3th rail of LRT in the functional property but the structure and shape of power rail is different with that. WE have to search the optimal power rail system for Korean MAGLEV vehicle. In this paper, we suggest the conceptual design and direction of design for power rail of Korean MAGLEV developing.

• Journal of the Korean Society for Railway
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• v.7 no.1
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• pp.37-48
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• 2004

In this paper, I explain the situations and problems which are focused on the rail freight system. We have a many problems, which have been showed the long freight logistics time, and inadequate fare system. And rail freight system does not have a efficient marketing system, and unit load system. Therefore rail freight has been decreased modal share, which is estimated from 9.65% in 1995 to 6.25% in 2001(ton base). Recently, EU nations and America rail freight system reveals a good outcome, which keeps the balance in the black. The main factors which go into the black, is the enlargement the investment in rail freight and efficient management focusing on the unit load system, fare system, and personnel management. I suggest the several improvement ways, which will be helpful to advance the rail freight system. Fistly, I suggest the speed up the freight rail and efficient fare system. Secondly, I propose the unit load system and the regulation the truck focusing on curtailment of the social cost. Lastly, I make an overture of establishment the comprehensive logistics system.

• Journal of the Korean Institute of Telematics and Electronics C
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• v.35C no.12
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• pp.59-65
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• 1998

In this paper, a novel rail-to-rail input stage circuit with improved transconductance Is designed. Its excellent performances over whole common-mode input voltage Vcm range is demonstrated by circuit simulator HSPICE. The novel input stage circuit comprises additional 4 input transistors and 4 current sources/sinks. It maintains DC currents of signal amplifying transistors when one of the differential input stage circuits operates, but it reduces these currents to 1/4 when both differential input stage circuits operates, As a result, a operational amplifier with the novel circuit maintains nearly constant transconductance performance and unity-gain frequency in strong inversion region. The novel circuit allows an optimal frequency compensation and uniform operational amplifier performance over whole Vcm range.

• Proceedings of the IEEK Conference
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• 1998.06a
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• pp.859-862
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• 1998

An offset compensation scheme for rail-to-rail CMOS op-amps with complementary input stages is presented. Two auxiliary amplifiers are used to compensate for the offsets of NMOS and PMOS differnetial input stages, and ping-pong control is employed for continuous-time operation. Simulation and measurements resutls show that offsets are reduced about 20 times by this scheme.

• Proceedings of the KSR Conference
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• 2000.11a
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• pp.60-67
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• 2000

The success of road haulage, in dominating the surface movement of freight, is now threatened by increased traffic congestion, falling average motorway speeds and rising in logistic costs. As a result, Government as well as companies, which use or operate logistics service, is now looking to rail to provide an alternative. First, we surveyed the bottlenecks and desired betterments to rail transport, which were indicated by rail and road transport users. Through the analysis of customers' needs survey. this paper is focused in the basic framework fur the rail freight transport, which could be helped to promote the efficiency associated with moving freight by rail.