• 제어로봇시스템학회논문지
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• 제10권3호
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• pp.232-238
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• 2004

The brake system of a high-speed train has a crucial role for the safety of human mass transportation. However, it is hard to acquire design parameters of the brake system in the design step of the new high-speed train. In this paper, we build a HILS (Hardware In-the- Loop Simulation) system for the brake system of the Korea High-Speed Train (KHST) that is supposed to run up to 350 km/h, and analyze the characteristics of the brake system of the KHST (composed of 7 cars) via real-time simulations. In the HILS system that is built using a DSP board of dSPACE, the dynamics of the 7 car bodies and several bogies and characteristics of springs and dampers of connection devices between cars are considered separately. Simulation results show that the designed brake system of the KHST is valid and satisfies design specifications.

• The Journal of Korean Physical Therapy
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• 제21권3호
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• pp.81-86
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• 2009

Purpose: This study compared the characteristics of the brake response time during the driving task between elderly and younger drivers. Methods: The participants consisted of an elderly group (n=12) and a younger group (n=12). The brake response time (BRT), which consisted of the reaction time (RT) and movement time (MT), was assessed in an actual driving car. The BRT was measured at the initiation and termination of the brake response for the driving task Results: The elderly group showed a significantly longer delay in the initiation and termination of the brake response than the younger group. The BRT correlated significantly with both the RT and MT. However, the RT showed a more significant correlation. Conclusion: A delay in the initiation and termination of the brake response may have clinical implications. A further study will be needed to determine the different factors contributing to the driving performance of elderly drivers.

• 에너지공학
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• 제23권2호
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• pp.170-174
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• 2014

This paper presents the influences of ethanol addition to gasoline on bench test a spark ignition engine performances and emissions characteristics. The use of ethanol gasoline blended fuels decrease the brake power and brake torque, and increases the brake specific fuel consumption (BSFC). Ethanol gasoline blended fuels show lower brake torque and brake power and higher BSFC than gasoline. When ethanol containing oxygen is blended with gasoline, the combustion of the engine becomes better and therefore CO emission is reduced. HC emissions decrease to some extent as ethanol added to gasoline increase, as the percentage of ethanol in the blends increased, NOx emission was decreased under various engine speeds.

• Tribology and Lubricants
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• 제30권4호
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• pp.240-245
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• 2014

Low alloy heat resistant brake disk and sintered brake pad are applied to mechanical brake system for the speed-up of urban rapid transit. In this research, we analyzed how the frictional characteristics between brake disk and pad are influenced by the disk mass. At a high disk mass, the friction stability was the lower value as a result of the lack of tribofilm formation at the disk surface. Wear rates of friction materials showed the higher value at a low disk mass and wear rates of 10 mm and 15 mm showed the similar level. Average friction coefficient was the lower value at the 10 mm disk thickness and range of variation of average friction coefficient was also the smaller value at the 10 mm disk thickness. However, there were no significant changes in the friction coefficients under any of test conditions. Surface roughness of a disk showed the highest value at the 5 mm disk and surface roughnesses of 10 mm and 15 mm showed the similar level. As a result, friction characteristics of disk mass influenced the friction stability, as well as the wear rate of friction pad and disk, but not the friction coefficient.

• 자동차안전학회지
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• 제14권2호
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• pp.90-95
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• 2022

Composite material is widely used in the automotive industries because it has excellent mechanical properties and is possible to reduce weight due to the low density. However, there is a new obstacle to meet environment regulation like Cu less or Cu free regulation for the friction material. Although it is strongly demanded, there are few research results about that unfortunately. Unless this problem is not solved properly, it is impossible to apply composite brake system to vehicle. In this paper, a new eco-friendly friction material for composite brake system is represented to respond these regulations. To do this, friction characteristics between existing low steel friction material and new eco-friendly friction material are verified to secure performances for brake system such as effect characteristic, fade characteristic and wear characteristic. And composite brake gets the equivalent or better performance compared to a low steel friction material. Finally, this result contributes to the study of major principles for the development of eco-friendly friction material in the future.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2007년도 춘계학술대회A
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• pp.1422-1427
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• 2007

MR fluid is a suspension of micrometer-sized magnetizable particles in silicon oil and a functional fluid whose apparent viscosity can be controlled by the applied magnetic field strength. In this paper, a rotary brake using MR fluid called MR brake for tension control of precision machinery such as roll-to-roll printing machinery is presented. First, to obtain the higher performance than conventional powder brake, a MR brake with a modified rotor shape is newly designed and analyzed using FEM. Second, the prototype of MR brake is fabricated with the optimized structural parameters and an experimental apparatus is constructed. Then, basic characteristics of the MR brake are investigated with the different MR fluids. Finally, the validity of the developed MR brake is verified through the comparison with the conventional powder brake.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2003년도 추계학술대회 논문집(III)
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• pp.377-382
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• 2003

In tread braking of freight cars, braking force is produced by the friction between the wheel and the braking shoe. Friction coefficients such as the brake power, weight variation and brake shoe types should be sensitively treated as the design parameters. The conditions of the car, empty and weighted, should also be taken into consideration in brake force design and the control of brake force has some limitations in terms of the brake system design so that the brake materials selection should be considered as important measures to solve that difficulties. Friction characteristics of brake materials should remain within the range of maximum and minimum value and the friction performance should remain stable regardless of braking time and temperature. This study presented an experimental evaluation method to secure optimum braking performance by keeping safe braking effect and braking distance by the friction coefficient of the brake shoe of the freight cars.

• 한국생산제조학회지
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• 제19권1호
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• pp.65-70
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• 2010

The effect of austempering treatment on the dynamic properties of a brake drum was investigated to primarily evaluate the potential damping advantage of an AGI (austempered gray iron) drum over a PGI (pearlitic gray iron) drum. This investigation provides valuable information for brake noise reduction since the brake drum is most often the outstanding component that generates the noise of the brake assembly. Test results show that the AGI drum provided slightly larger damping values than the PGI drum for the first few major resonances observed. A finite element model of a drum was also developed to aid in studying its dynamic behavior. A good correlation was obtained between the analytical results and the actual measurement data.

• 한국정밀공학회지
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• 제21권11호
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• pp.171-178
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• 2004

This paper presents vibration characteristics of a wire cut discharge machine in which an electro-rheological brake actuator is used to control the wire tension. The ER brake actuator has several advantages including design simplicity, fast response time and real-time controllability. On the basis of the tension level required in the machine an appropriate size of the ER brake actuator is devised. The ER brake actuator is then incorporated with the machine and the field-dependent wire tension is experimentally evaluated. The straightness of the workpiece is also empirically investigated by changing the intensity of the electric field.

• 한국기계가공학회지
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• 제21권4호
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• pp.39-45
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• 2022

In this study, it was verified that carbon-ceramic brake discs can replace existing cast-iron brake discs of the same size. In addition, a method of pretreating carbon fiber to secure heat dissipation characteristics while using a small amount of carbon fiber was established. The thermal conductivity and bending strength characteristics were analyzed according to the carbon content, and brake braking tests were conducted. Through pretreatment, the maximum temperature was lowered by 16 ℃ compared to the case using only carbon fiber, and the cooling rate was improved by approximately 10% compared to metal brake discs. However, the total heat capacity increased as the mass increased owing to the reaction. Thus, the measured temperature was higher than that of the metal brake disc; therefore, additional research is required.