• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 1995년도 추계학술대회 논문집
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• pp.747-750
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• 1995

As railway trains run faster high performance braking system are necessary because more energy needs to be dissipated due to increased kinetic energy. In this work a portable computer based prediction system for emergency braking distance has been developed. The algorithm for the system is based on braking theory and empirical results of actual braking test. The computer is connected to the sensors to measure the velocity and the braking pressure in real train. It is expected that this system will be utilized to predict emergency braking distance during actual operation of the train

• 대한기계학회:학술대회논문집
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• 대한기계학회 2004년도 춘계학술대회
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• pp.519-524
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• 2004

This study is concerned with the braking distance estimation using frictional energy rate. First, steady state rolling analysis is performed, and using this result, the braking distance is estimated. Dynamic rolling analysis during entire braking time period is impratical, so that this study divides the vehicle velocity by 10km/h to reduce the analysis time. The multiplication of the slip rate and the shear stress provides the frictional energy rate. Using frictional energy rate, total braking distance is estimated, In addition, ABS(Anti-lock Brake System) is considered, and two type of slip ratios are compared, One is 15% slip ratio for the ABS condition, and the other is 100% slip ratio which leads lo the almost same braking distance as the elementary kinematic theory. A slip ratio is controlled by angular velocity in ABAQUS/Explicit, A 15% slip ratio gives the real vehicle's braking distance when the frictional energy occurred al disk pad is included. Disk pad's frictional energy rate is calculated by the theoretical approach.

• 대한전기학회논문지:전기기기및에너지변환시스템부문B
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• 제52권8호
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• pp.390-396
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• 2003

This paper is focused on an optimal block sectioning technique which are widely used in conventional railway system. We studied braking distance with pure train braking performance to generalize train braking. We tried to apply the braking distance to wayside signaling system to decide optimal block sectioning to reduce headway. The braking distances are obtained for 2 aspects, 3 aspects, 4 aspects and n aspects such that step speed control, are longer than the pure braking distance. We found an optimal solution with the generalized n aspects, and a minimum block distance for ATO mode.

• 대한교통학회지
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• 제29권3호
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• pp.115-122
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• 2011

이 논문은 자동차의 급제동시 발생되는 스키드마크(skid mark, 활주거리)를 통해 제동직전 속도(Pre-braking Speed)를 정확히 산정하기 위한 방법론을 제시하고자 한다. 운전자는 전방에 위급한 상황이 전개되거나 불의의 사고에 처하게 되었을 경우 통상 급제동조치를 취하게 되며, 정지거리에 따라 사고를 당할 수도 있다. 자동차의 정지거리에 있어서 영향을 끼치는 요인은 운전자의 인지반응시간, 자동차 제동장치의 성능, 노면의 상태 등을 꼽을 수 있으나, 가장 중요한 요인은 제동직전 속도(Pre-Braking Speed)라고 할 수 있다. 현재 교통사고의 조사분야에서는 skid mark의 길이에 근거한 활주직전 속도(Preskidding Speed)를 산정하여 과속 여부를 판단하고 있으나, 정확한 사고원인 규명을 위해서는 불완전제동시간 동안 감속된 속도를 고려한 제동직전 속도의 산정이 필요할 것으로 판단된다. 따라서, 본 연구에서는 교통사고시 자동차의 정확한 속도정보를 산정하기 위한 방법을 제안하고자 하며, 또한 이 연구가 향후 교통안전차원에서 자동차의 특성을 이해하는데 있어서 일조할 수 있기를 기대한다.

• Wind and Structures
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• 제19권1호
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• pp.1-14
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• 2014

Rail-mounted cranes can be easily damaged by a sudden gust of wind while working at a running speed, due to the large mass and high barycenter positions. In current designs, working rail-mounted cranes mainly depend on wheel braking torques to resist large wind load. Regular brakes, however, cannot satisfactorily stop the crane, which induces safety issues of cranes and hence leads to frequent crane accidents, especially in sudden gusts of wind. Therefore, it is necessary and important to study the braking performance of working rail mounted cranes under wind load. In this study, a simplified mechanical model was built to simulate the working rail mounted gantry crane, and dynamic analysis of the model was carried out to deduce braking performance equations that reflect the qualitative relations among braking time, braking distance, wind load, and braking torque. It was shown that, under constant braking torque, there existed inflection points on the curves of braking time and distance versus windforce. Both the braking time and the distance increased sharply when wind load exceeded the inflection point value, referred to as the threshold windforce. The braking performance of a 300 ton shipbuilding gantry crane was modeled and analyzed using multibody dynamics software ADAMS. The simulation results were fitted by quadratic curves to show the changes of braking time and distance versus windforce under various mount of braking torques. The threshold windforce could be obtained theoretically by taking derivative of fitted curves. Based on the fitted functional relationship between threshold windforce and braking torque, theoretical basis are provided to ensure a safe and rational design for crane wind-resistant braking systems.

• 대한전기학회논문지:전기기기및에너지변환시스템부문B
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• 제52권8호
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• pp.397-404
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• 2003

In part I, we studied only step speed control for train, the second part extended to beacon signaling system and moving block system. With the calculated braking distance in part I, part II showed how to reduce headway using the beacon signaling system and moving block system, revealed that the beacon system has a braking distance advantage for sighting allowance with compared to step speed control, proposed beacon installation interval and revealed the braking distance with moving block system being nearly approached to train pure braking distance. We compared three different train control system to decide the best signaling system for a given condition and obtained the result that three systems have a same headway near 10～13 steps speed control.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2005년도 학술대회 논문집 정보 및 제어부문
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• pp.222-224
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• 2005

In the development of Antiskid Brake System(ABS) for a fixed-wing aircraft, the braking efficiency is the most essential parameters to evaluate the ABS, especially in slippery road conditions. The braking distance and landing distance of the aircraft depends on it. Since the ABS has been designed and implemented as a subsystem of the aircrafts, the braking performance was evaluated under dynamometer test, where the dynamometer emulates the aircraft mass. Under simulated wet road conditions, the dynamometer starts to be braked. This paper suggests practical braking efficiency calculation methods and the results and finally compares each method.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2000년도 추계학술대회논문집A
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• pp.87-92
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• 2000

In this paper, we investigated the braking performance of a composite brake shoe for power car. Laboratory bench test and field tests were carried out to characterize the braking performance by the parameters such as friction coefficient, wear rate, braking temperature and stopping distance. Density distribution was found to have a significant influence on the wear rate. The composite brake shoe with even density distribution showed better braking performance. The braking performance of a composite brake shoe was also compared with that of a cast iron brake shoe which is currently being used. The result indicated the performance of the composite brake shoe is better than the cast iron brake shoe.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2011년도 춘계학술대회 논문집
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• pp.554-559
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• 2011

Braking performance of a trainset that consists of a locomotive and several coaches and/or wagons is influenced by that of the locomotive as well as each coach or wagon. For trains to safely travel on a railway, trains must be provided with sufficient distance where to stop. Thus, replacing coaches or wagons needs calculating, measuring the braking performance such as a stopping distance or a deceleration. The task is further complicated if there are many kinds of trains with different braking performance characteristics. The accurate calculation is subject to acquire accurate information on the existing cars. Moreover, the initiation of braking by a driver or the geometry of the track affects as complicated factors. In this paper, based on the braking performance test conducted for US-SCRRA coaches, introduced several factors assumed to influence the result and the compensating methodology.

• 한국철도학회논문집
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• 제10권2호
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• pp.153-160
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• 2007

To start or stop the train safely within the limited traveling distance, it is necessary to guarantee the proper traction or braking force. Presently, most trains are run by the electrical power and have adopted a combined electrical and mechanical(friction) braking system. In order to design a good traction or a brake system, it is essential for designers to predict the traction or brake performance. In this paper, the traction/coasting/braking performances analysis program has been developed and verified by comparing the simulation results with on-line test results of the Korean high speed train(HSR-350); Both results match very well. Consequently, the designers can predict the traction/coasting/braking performances of trains by using the proposed program under various operating conditions.