• Structural Engineering and Mechanics
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• 제75권4호
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• pp.435-444
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• 2020

Ultrasonic guided wave testing is a very promising non-destructive testing method for rails, which is of great significance for ensuring the safe operation of railways. On the basis of the semi-analytical finite element (SAFE) method, a analytical model of 59R2 grooved rail was proposed, which is commonly used in the ballastless track of modern tram. The dispersion curves of ultrasonic guided waves in free rail and supported rail were obtained. Sensitivity analysis was then undertaken to evaluate the effect of rail elastic modulus on the phase velocity and group velocity dispersion curves of ultrasonic guided waves. The optimal guided wave mode, optimal excitation point and excitation direction suitable for detecting rail integrity were identified by analyzing the frequency, number of modes, and mode shapes. A sinusoidal signal modulated by a Hanning window with a center frequency of 25 kHz was used as the excitation source, and the propagation characteristics of high-frequency ultrasonic guided waves in the rail were obtained. The results show that the rail pad has a relatively little influence on the dispersion curves of ultrasonic guided waves in the high frequency band, and has a relatively large influence on the dispersion curves of ultrasonic guided waves in the low frequency band below 4 kHz. The rail elastic modulus has significant influence on the phase velocity in the high frequency band, while the group velocity is greatly affected by the rail elastic modulus in the low frequency band.

• 비파괴검사학회지
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• 제26권6호
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• pp.411-416
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• 2006

The critical subject of transverse crack detection in a rail head is treated in this paper. Conventional bulk wave ultrasonic techniques oftenfail because of shelling and other surface imperfections that shield the defects that lie below the shelling. A guided wave inspection technique is introduced here that can send ultrasonic energy along the rail under the shelling with a capability of finding the deleterious transverse crack defects. Dispersion curves are generated via a semi analytical finite element technique along with a hybrid guided wave finite element technique to explore the most suitable modes and frequencies for finding these defects. Sensor design and experimental feasibility experiments are also reported.

• International Journal of Safety
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• 제8권2호
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• pp.1-4
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• 2009

Various falling prevention systems with vertical guided rail have been supplied in order to prevent falling accidents and acquire the long life and cost down for the maintenance. Almost the imported system is composed of a guided rail and the comfort components. It has the mechanism that cannot be dismounted from the guided rail at the accident site. Thus, the aim of this study is to develop a falling prevent system that has a direct dismounting function, which can release easily from the falling accident point. This system has a high durability and robust. And the cost efficiency of the system and safety for workers also are improved remarkably. From the results, we showed the proposed new falling system is sufficiently safety and satisfies the KOSHA regulation through the numerical stress analysis. Also it is expected as the useful and effective safety device for workers.

• 전기학회논문지
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• 제66권5호
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• pp.792-799
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• 2017

The real time unmanned monitoring system of an equipment's internal parts and condition requires the monitoring device to be able to stop at a set location on the rail. However, due to the slip between the driving surface and the roller, an error occurs between the actual position and the command position. In this paper, a method to compensate the position error due to the roller slip is proposed. A proximity sensor located at both ends of the rail detects the starting point and the maximum position pulse, linearly compensating the error between the angular position of the motor and the mechanically fixed starting and maximum position pulse of the rail in forward and reverse direction. Moreover, unlike the existing servo position controller, the motor adopts the position detection method of Hall sensor in BLDC (Brushless DC) and applies an algorithm for low-speed driving so that a stable position control is possible. The proposed rail guided unmanned monitoring system with driving slip compensator was tested to verify the effectiveness.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2004년도 춘계학술대회 논문집
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• pp.1266-1273
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• 2004

Urban railway signaling system is for train operation with safety in the urban crowded area, that has been increasing the demand of use of advanced train control systems with safe. European Commission is supporting the UGTMS(Urban Guided Transport Management System) project for the research and development. The main objective of UGTMS is to provide the European urban guided transport sector (comprising metro, tram and light rail systems) with a common Management System. A key topic is the extent to which the specifications for the successful ERTMS(European Rail Transport Management System) can be adapted to UGTMS needs. Beyond this, it is necessary to define the relevant functional and system requirements for all types of urban guided transport management systems in order to improve interoperability and intermodality. Also to be explored are the prospects for open system standards. In this article, we look into the trend of the standardization through the UGTMS project in Europe and consider any benefit to the project of the standardization for the urban railway signaling system in Korea.

• 대한기계학회논문집A
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• 제35권10호
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• pp.1257-1264
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• 2011

짧은 시간에 장거리를 전파하는 유도 초음파의 특성을 이용하면 빠르게 넓은 영역의 검사가 가능하다. 그러나 레일의 경우와 같이 단면이 단순하지 않고 임의의 형상을 갖는 구조물의 경우 초음파 전달시 발생하는 분산 특성이나 다수의 모드의 발생으로 초음파 신호의 분석에 어려움을 겪는다. 따라서 실용적인 유도 초음파 검사 시스템을 개발하기 위해서는 먼저 레일내를 전파하여 전달되는 초음파의 거동특성을 이해하여야 한다. 특히 레일내를 전파하는 초음파의 분산특성은 필수적으로 확인되어야 할 특성이다. 본논문에서는 SAFE법을 활용하여 KS60 레일내를 전파하는 초음파의 분산곡선을 구하는 방법을 소개하고 유도초음파를 활용한 레일 검사의 가능성에 대하여 살펴보았다.

• 비파괴검사학회지
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• 제24권2호
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• pp.125-135
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• 2004

This paper describes the calculation technique for guided wave propagation with a semi-analytical finite element method (SAFEM) and shows some results of numerical calculation and guided wave simulation for plates, pipes and railway rails. The SAFEM calculation gives dispersion curves and wave structures for bar-like structures. Dispersion curve software for a pipe is introduced, and also dispersion corves for a rail are given and experimentally verified. The mode conversions in a plate with a defect and in a pipe with an elbow or a defect are shown as examples of our guided wave simulations.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2009년도 제40회 하계학술대회
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• pp.1195_1196
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• 2009

Light rail transit is classified to rubber-tired LRT, lear induction motor LRT, steel wheel LRT, monorail and tramway. LRT except for tramway are usually operated without driver and tramway are driven depending on driver's sight like usual car. LRT, which is one type of urban guided transit, shall be operated according to domestic "Operational Regulation for Urban Guided Transit" but existing regulation does not contain the safety related codes for driverless operation. In this paper, we investigate "IEC 62267 : Railway Application-Safety Requirements for Automated Urban Guided Transit" and compensate for existing operational regulation by referring to international standard and operational rule of commercial line.

• 전기학회논문지
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• 제66권4호
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• pp.701-708
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• 2017

This paper proposes an optimum design method using Teaching-Learning-based optimization for the fuzzy PID controller of Magnetic levitation rail-guided vehicle. Since an attraction-type levitation system is intrinsically unstable, it is difficult to completely satisfy the desired performance through the conventional control methods. In the paper, a fuzzy PID controller with fixed parameters is applied and then the optimum parameters of fuzzy PID controller are selected by Teaching-Learning optimization. For the fitness function of Teaching-Learning optimization, the performance index of PID controller is used. To verify the performances of the proposed method, we use a Maglev model and compare the proposed method with the performance of PID controller. The simulation results show that the proposed method is more effective than conventional PID controller.

• 전력전자학회논문지
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• 제22권3호
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• pp.223-230
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• 2017

A low-cost BLDC motor with hall sensor is used to drive the position control of a facility security monitoring system in this paper. Low measurable frequency of the hall sensor signal in low-speed regions results in difficulty in obtaining accurate speed detection and position control. To improve system control performance, we propose a variable gain of position controller and stop mode control scheme according to the motor speed and error position with pre-set deceleration time. The proposed stop mode control scheme is activated around the stop position to forcibly move the BLDC motor to the stop position in low speed. In the proposed stop mode, the motor current is controlled by the actual speed with the reference rotating angle. The control performance of the proposed position control is verified through experiments at the actual rail guided facility security monitoring system.