• Journal of Korean Society of Transportation
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• v.29 no.3
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• pp.115-122
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• 2011

This paper investigates the accuracy of the vehicle pre-braking speed estimated based upon measured skidding distance. Driver ordinarily takes sudden braking when urgent situation is developed in the front or when the driver is involved in an unexpected situation, and the driver may be inflicted upon an accident depending on the required stopping distance. Among factors influencing the stopping distance of vehicle such as recognition response time of driver, performance of vehicle's braking device, and state of road surface etc, pre-braking speed is seemingly the most important influencing factor. Currently, in the investigating section of traffic accidents, the state of overspeed is determined by the pre-skidding speed calculated based on the length of skid mark. In order to identify the accurate cause of the accident, it is strongly recommended that estimation of pre-braking speed should be estimated taking into account speed reduction during transient time. In this study, we propose a method for estimating more accurate exact speed information of vehicle at the time of traffic accident. The outcomes from this study potentially help better understanding of the characteristics of vehicle for traffic safety in the future.

• Journal of Korean Society of Transportation
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• v.30 no.5
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• pp.83-90
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• 2012

Driver ordinarily takes sudden braking when urgent situation is developed or when the vehicle is involved in an unexpected accident. Therefore, the most common trace at a traffic accident scene is skid mark. Currently, in investigating traffic accident, overspeed is determined by the length of skid mark. However, in order to identify accurate cause of accident, estimation of pre-braking speed which takes into account speed reduction during transient time should be considered as a requirement. In a recent study, several ways to estimate pre-braking speed were suggested, but none considered to differentiate the decelerating transient brake section and skidding section. This study analyzed trends of decelerating transient brake section and skidding section by real braking test.

• Proceedings of the KSR Conference
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• 2011.10a
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• pp.1943-1952
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• 2011

Rail vehicle brakes partly or completely transform the kinetic energy of moving vehicles into other forms of energy, in order to reduce the speed, and if necessary to bring them to a halt. To fulfil these requirements, the effect of a certain brake force is necessary and especially it is considered that the brake force is a important device to rail vehicles as a mass transit. The brake distance is a criterion for measuring brake force. The brake force is measured via dozens of brake distance test before its service operation. The brake distance is influenced by cars and rail conditions; weight of cars, speed on the verge of braking, temperature of brake disk and condition of the upper side of rail, etc. Therefore we will study how the these factors impact with the brake distance via a real test results.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.21 no.10
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• pp.581-588
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• 2020

This study examined a brake pad wear compensation method for an Electro-Mechanical Brake (EMB) using the braking test device. A three-phase Interior Permanent Magnet Synchronous Motor (IPMSM) was applied to drive the actuator of an EMB. Current control, speed control, and position control were used to control the clamping force of the EMB. The wear compensation method was performed using a software algorithm that updates the motor model equation by comparing the motor output torque current with a reference current. In addition, a simple first-order motor model equation was applied to estimate the output clamping force. The operation time to the maximum clamping force increased within 0.1 seconds compared to the brake pad in its initial condition. The experiment verified that the reference operating time was within 0.5 seconds, and the maximum value of the clamping force was satisfied under the wear condition. The wear compensation method based on the software algorithm in this paper can be performed in the pre-departure test of rolling stock.

• The Transactions of the Korean Institute of Power Electronics
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• v.8 no.6
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• pp.496-503
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• 2003

SFC system has come to be used as drive large synchronous machine in many industry applications. Many papers have been presented on the control algorithm of SFC system, not the acceleration and start-up but the rated speed operation with line connection and the braking operation with regeneration which is used in the industry. This paper presents the whole section control algorithm for a large synchronous machine using SFC system. The results of experiment show that the proposed algorithm is proper and effective.

• Journal of Advanced Navigation Technology
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• v.14 no.1
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• pp.93-101
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• 2010

In this study, the performance characteristics of turbocharged engine is analyzed. The methods of engine performance improvements are suggested not only for full load characteristics of the engine but also for partial load characteristics of the engine, which is more frequently used in actual driving conditions. The compression ratio of the compressor is increased rapidly in a straight line pattern until 1260 engine rpm, and after that it is increased slowly to 2.5 ratio. Also the brake mean effective pressure increased until 1260 engine rpm and decreased rapidly after 1600 engine rpm. The higher the pressure ratio, the better the fuel consumption, air excess ratio and brake mean effective pressure. But those are higher in the rated revolution range than in the mid-low revolution range. The turbocharger is operated in a stable condition from 1260 rpm and its efficiency is low in the low speed range for the reason of its characteristics. The results of this study can be applied in the fundamental control methods of turbocharged engine for stable load and speed.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.18 no.6
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• pp.202-210
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• 2019

This paper evaluated the performance of passenger vehicles with an AEB(Autonomous Emergency Braking) for various pedestrian-vehicle collision situations. The experiment was conducted at a speed of 30-60km/h on a 2017 3,000cc vehicle using a range of collision scenarios. The results showed that the test vehicle stopped before crashing a pedestrian dummy under all scenarios at 30km/h. The test vehicle reduced the speed but crashed the pedestrian dummy in all scenarios at 40-60km/h. From the paired t-test, there was a speed difference from the AEB system at a significant level of 0.05. In addition, the percentage of speed reduction was quite different for each scenario tested. It was concluded that the current AEB system can prevent pedestrian collisions at speed of 30km/h, but cannot prevent collisions with pedestrians at speed of 40-60 km/h.

• Journal of Advanced Navigation Technology
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• v.24 no.4
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• pp.280-284
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• 2020

To improve maintenance, environmental issues, efficiency, and economics to supplement the current air braking problems, braking power related to the entire driving range of electric brakes was presented in all areas from stop to high speed. As a result, the efficiency of braking power and cutting-edge technology have expanded energy use, and through this paper, noise in all driving ranges can be reduced, and maintenance costs can be reduced. The traction motor must bring the variable speed of the traction motor and the terminal voltage of the traction motor to drive high-speed driving characteristics that control the maximum voltage of the inverter. Therefore, we studied driving and brake changes through simulation.

• Korean Journal of Applied Biomechanics
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• v.19 no.3
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• pp.539-547
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• 2009

The purpose of this study was to investigate the changes of kinetic and kinematic parameters in obstacle gaits after 12 weeks of an aquatic exercise program. Eight female elders walked in four different heights of obstacles(0, 2.5, 5.1, & 15.2cm) on their self-selected speed. The ROM of hip was significantly increased after the aquatic exercise program. Swing and Stance duration were decreased. The step length was significantly increased and the step width was decreased. After the exercise program the clearance between the right foot and the top of obstacle(except 15.2cm) increased and the crossing speed was increased. The braking force, propulsive force, braking impulse, and propulsive impulse were significantly changed after the aquatic exercise program. The 12 weeks of the aquatic exercise program resulted in lower body strength and balance gains in female elders. The improvements were associated with changes in kinetic and kinematic parameters leading to an obstacle-crossing speed and a safer lower-limb control. The aquatic exercise program is suggested as an effective intervention to promote gait ability and prevent fall-related to the injuries.

• The Journal of Society for e-Business Studies
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• v.21 no.3
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• pp.79-99
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• 2016

Supply network of automobile part is addressed with the e-invoices generated at real time. Automobile is composed of 8 modules. Firms which produce these modules are defined as the first outsourcing firm. Brake is the part of power control module and so, brake manufacturing firm is called the second outsourcing firm. In this paper, the third supply networks of brake manufacturing firms is analyzed with e-invoices and social network method. At the node-level, the third outsourcing firms are classified into 3 categories, interator, allocator and hub with respect to their role at the ego-network of each brake manufacturing firm. At the network level, A2, one of 3 brake manufacturing firms have more outsourcing firms and bigger centrality than the other brake manufacturing firms. Intre-firms trade patterns are, also, analyzed by using the degree of trade dedication with respect to the modes of business. It is shown that trade pattern of retail, commodity brokerage firm, rubber and plastic manufacturing firm are hierarchical trade because their degree of trade dedication is almost near to 1.