• International Journal of Railway
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• v.6 no.4
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• pp.148-154
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• 2013

This article has tried to review the maximum contact stresses in the contact area of the wheel and rail as a result of lateral movement of the wheel on rail by taking advantage from Hertz theory. Since wheel movement on rail is accompanied by lateral movement due to wheel profile conisity, so the contact point of wheel and rail is not constant and the contact stresses are therefore changeable in every single moment. Since the shape of rail profile and rail inclination, wheel diameter and the mechanical properties of the wheel and rail are effective on the stresses of contact area, these parameters have been studied by applying Hertz theory. This article aims to calculate the contact stresses in different parts on the wheel surface by using Hertz theory.

• Proceedings of the KSR Conference
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• 2001.10a
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• pp.467-474
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• 2001

The KNR(Korean National Railroad) is trying to set a new rail standard to back up the speed-up policy of the conventional railways. This work has passably significance since the rail standards used were introduced from Japan without the consideration on our situation. The contact analysis between wheel treads and rail heads, attended with complex calculation and the wear experiments taken long time should be accomplished for the exact investigation to establish a new rail standard. However, this paper just concentrates the structural investigation of the proposed rail standard and the dynamic analysis between trains and rail models with intent to shift the above procedure on the next step.

• Proceedings of the KSR Conference
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• 2004.10a
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• pp.750-755
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• 2004

This paper deals with the domestic status of rail gap and criteria of the maximum allowable rail gap for the broken rail. Parameteric studies about the maximum allowable rail gap were accomplished by the zimmermann model. The dynamic behavior of broken rail not to be explained by the existing theory was looked into. When a train is travelling along rail gap for the broken rail, dynamic behaviors of rail system and train are abruptly changed. And the opinion about a permission criteria of the rail gab was presented.

• The Journal of the Convergence on Culture Technology
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• v.4 no.3
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• pp.213-220
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• 2018

The objective of this study was to estimate the optimum spacing of rail joint for a personal rapid transit(PRT) track system, and to compare the results with the normal rail and rail joint by performing the finite element analysis(FEA) and field measurements using actual vehicles. Based on the FEA and field measurement results compared, the optimum spacing of the rail joints was calculated to be maximum of 1.20m based on the rail displacement. The vertical displacement of the normal rail was higher than that of the rail joint at a spacing of 1.0m, but it was considered that the vehicle riding performance and serviceability of track would be improved in terms of the stability of the train due to similar to rail defection between normal rail and rail joint. Also, because of the proposed rail joint spacing in this study was longer than the current rail joint spacing, the economic effect would be expected by decreasing the amount of sleepers.

• Journal of the Korean Society for Railway
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• v.18 no.4
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• pp.289-300
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• 2015

An important source of noise from railways is rolling noise caused by wheel and rail vibrations induced by acoustic roughness at the wheel-rail contact. In conventional approaches to predicting rail noise, the rail is regarded as placed in a free space so that the reflection from the ground is not included. However, in order to predict rail noise close to the rail, the effect of the ground should be contained in the analysis. In this study the rail noise reflected from the ground is investigated using the wavenumber domain finite element and boundary element methods. First, two rail models, one using rail attached to the rigid ground and one using rail located above rigid ground, are considered and examined to determine the rigid ground effect in terms of the radiation efficiency. From this analysis, it was found that the two models give considerably different results, so that the distance between the rail and the ground is an important factor. Second, an impedance condition was set for the ground and the effect of the ground impedance on the rail noise was evaluated for the two rail models.

• Proceedings of the KIEE Conference
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• 2007.10c
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• pp.238-240
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• 2007

This paper present adaptation method of rail potential test to verify DC railway system's performance and safety. For protection of person and utility caused by rail potential rise, international standard to limit rail potential rise is made and rail potential is tested at the time of plan and construction of DC railway system in foreign country. So, we need rail potential test at the opening time and prepare a continuous monitoring technique of rail potential and a limitation method of rail potential rise. For these, we describe cause of rail potential rise, international standard about rail potential, protection principle, an example of calculation and measurement, and adaptation method for performance test.

• Journal of the Korean Society for Railway
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• v.3 no.4
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• pp.185-193
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• 2000

In general, a third rail current collecting shoegear is widely used in the light rail transit system since it is more efficient and economical than an overhead pantograph. Therefore, its specification is prescribed in the Korean standard specifications for the light rail transit for its applications. This paper describes the development of the third rail current collecting shoegears which is suitable to Korean situation and satisfactory to the Korean standard specifications. Two types are developed for the steel wheel and the rubber tyred AGT system, and various experiments are executed. It is found that performance of the third rail current collecting shoegear developed is proved acceptable.

• Journal of IKEEE
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• v.22 no.4
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• pp.1218-1221
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• 2018

This paper presents a low-power 0.6-V 10-bit 200-kS/s double rail-to-rail successive approximation register (SAR) analog-to-digital converter (ADC). The proposed scheme allows input signal with 4 times power which is compared with conventional one by applying proposed rail-to-rail scheme, and that improves signal-to-noise ratio(SNR) of NTV SAR ADCs. The prototype was designed using 65-nm CMOS technology. At a 0.6-V supply and $2.4-V_{pp}$ (differential) and 200-kS/s, the ADC achieves an SNDR of 59.87 dB and consumes 364.5-nW. The ADC core occupies an active area of only $84{\times}100{\mu}m^2$.

• Journal of the Korean Society for Railway
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• v.19 no.4
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• pp.489-497
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• 2016

The rail fastening system, which provides a structural connection between the rail and the sleepers, is a main track component that plays an important role in retaining the rail gauge within acceptable tolerances, as well as in passing the train load to the roadbed through the sleepers. In this paper, a modal test was first performed to evaluate the dynamic characteristics (e.g., natural frequency) of the clips of the railway fastening system under the condition of rail corrugation in urban railway operation. The corrugation-induced passing frequency was then compared with the natural frequency of the clips to investigate any resonance effect during train passage. Furthermore, a field test under train passage was conducted to measure the accelerations on the rail and the rail fastening clips as well as the strains on the rail fastening clips in the rail corrugation condition. The field measurements indicated that the accelerations on the rail and the rail fastening clips have a close relationship with the rail corrugation, but they had a minimal effect on the strains of the rail fastening clips.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.49 no.2
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• pp.39-46
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• 2012

The newly designed sense amplifier in this paper has rail-to-rail input range achieving low power consumption. Reducing static power consumption generated due to DC path to ground is key element for low power consumption in this paper. The proposed sense amplifier performs power-saving operation using negative feedback circuit that controls the current flow with the newly added PMOS input terminal. As a simulation result, the proposed sense amplifier consumed about over 50 % efficiency of the average power consumed by the typical Rail-to-Rail sense amplifier.