• Journal of the Korea Academia-Industrial cooperation Society
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• v.13 no.5
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• pp.1969-1975
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• 2012

The air brake system used in heavy vehicle is very important from the point of safety due to its weight. In general, air brake system generates relatively long response time and large loss of pressure. It is known that the response time can be decreased by optimal design of brake system, i.e., by increasing the system pressure, minimizing the air line, and material of components. In this study, We developed experimental rigs for the measurement of braking response of heavy duty trucks and compared with the simulated results obtained from the net work fluid flow system analysis code (FLOWMASTER). The effect of several parameters such as, system pressure, diameter of pipe, chamber temperature on the brake response performance have been examined.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 2002.04a
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• pp.134-139
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• 2002

Motorcycle industry, for its competitive position, depends on part design technology. This part design has a bulky amount of data and asks the accumulation of advanced technical skill and experience, and fragmentary technical application is not enough to get to the kernel of a problem. Therefore, the improvement of proper productivity - the starting point of engineering design - and useful Design Methodology for products manufacturing are needed. Thus this paper is aimed to create a program that outputs dynamic characteristics of a vehicle when the data from fully understanding on motorcycle's brake system and induced formula for brake design are inputted.

• Transactions of the Korean Society of Machine Tool Engineers
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• v.12 no.1
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• pp.101-110
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• 2003

Motorcycle industry, for its competitive position, depends on part design technology. This part design has a bulky amount of data and asks the accumulation of advanced technical skill and experience, and fragmentary technical application is not enough to get to the kernel of a problem. Therefore, the improvement of proper productivity - the starting point of engineering design - and useful Design Methodology for products manufacturing are needed. Thus this paper is aimed to create a program that outputs dynamic characteristics of a vehicle when the data from fully understanding on motorcycle's brake system and induced formula for brake design are inputted. This paper is intended to show a creative design method by the thermal analysis data through FEM study and using shape design parameters derived from our programs.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.22 no.3
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• pp.654-662
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• 1998

Shift quality of an automatic transmission in a vehicle is mainly affected by transient pressures in the hydraulic system during shifting. In this study, dynamic modelings of the hydraulic system and the power train of an automatic transmission are made systematically by a bond-graph method. The dynamic characteristics of the line pressures and clutch/brake pressures during shiftings are investigated by simulations and verified by experiments. The effects of clutch/brake pressures on the shift torque are also investigated through driving simulation.

• Transactions of the Korean Society of Automotive Engineers
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• v.4 no.4
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• pp.156-163
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• 1996

The brakes are the most important safety-critical accident avoidance components of a motor vehicle. They must perform safely under a variety of operating conditions and must have enough strength not to fail during the life of a vehicle. Recently, anti-lock brake systems are used on more and more passenger cars. The ABS brakes modulate brake line pressure to prevent brakes from locking during braking. In this study, finite element analysis, material test for FCD45, measurement of stress and cumulative fatigue damage analysis were performed to evaluate fatigue damage of the caliper housing under ABS mode.

• Tribology and Lubricants
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• v.30 no.3
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• pp.183-188
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• 2014

In this paper, we present our analysis of tribological failure examples for an anti-lock brake system(ABS) in a car. The study range of this paper is to improve the quality of ABS system by analyzing with sensor, computer, actuator and oil lines. In the first example, the brake leak from hydraulic supply line in a caliper on the rear left side of the ABS hydraulic modulator. This produces the sponge phenomenon, where the car does not brake even when the driver operates the brake pedal. The hydraulic unit operating ABS is actuator that play role regulating drive condition according with the oil pressure supplied with wheel of a car. In the second example, the service man does not completely tighten the fixed bolt after repairing the car. This causes the ABS warning lamp to light up as the ABS wheel speed sensor cannot detect whether the ABS has been activated. In the third example, the ABS electronic control unit is separated from the soldered part of the inner circuit board. Consequently, the ABS fails in control because the ABS motor pump receives no-signal for the hydraulic unit. The wheel speed sensor has to large durability because of giving signal of acting condition to computer by detected the acceleration and deceleration of wheel of a car. In the fourth example, the ABS warning lamp lights up of when cracks propagate in the circuit board soldering part. The circuit of this computer is very important part for input and output the operating signal of system. Such failures can aggravate the durability of the ABS. Thus, the ABS needs to be optimized to eliminate malfunction phenomenon.

• 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.

• Proceedings of the KIEE Conference
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• 2005.07d
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• pp.3081-3083
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• 2005

한국형 고속전철차량의 자동제어 구현을 위해서 우선 다양한 종류의 장치들로부터 상태정보(Line Voltage-열차가선전압, Bogie Hunting, Preset Speed, PWM, Train Velocity, Brake Pressure, Reservoir Pressure)를 취득해야하며, Main Process Unit(MPU)에서의 고속 Data 처리를 위해서 취득한 Analog Data를 신속하게 Digital Data로 변환해야 한다. 또한 열차내의 특수한 조건(Noise, Vibration)에서도 안정적인 데이터의 취득을 만족시켜야한다. 이와 같은 상황을 고려한 독자적이 통합형 데이터 취득 장치 -Integrated Data Acquisition Board(IDAB)-의 설계방안을 제시하였다.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.11 no.4
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• pp.1178-1185
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• 2010

Recently, high speed of container freight cars is causing fatigue damage of wheel. Sudden failure accidents cause a lot of physical and human damages. Therefore, damage analysis for wheel prevents failure accident of container freight car. Wheel receives mechanical and thermal loads at the same time while rolling stocks are run. The mechanical loads applied to wheel are classified by the horizontal load from contact of wheel and rail in curve line section and by the vertical force from rolling stocks weight. Also, braking and deceleration of rolling stocks cause repeated thermal load by wheel tread braking. Specially, braking of rolling stocks is frictional braking method that brake shoe is contacted in wheel tread by high breaking pressure. Frictional heat energy occurs on the contact surface between wheel tread and brake shoe. This braking converts kinetic energy of rolling stocks into heat energy by friction. This raises temperature rapidly and generates thermal loads in wheel and brake shoe. There mechanical and thermal loads generate crack and residual stress in wheel. Wetenkamp estimated temperature distribution of brake shoe experimentally. Donzella proposed fatigue life using thermal stress and residual stress. However, the load applied to wheel in aforementioned most researches considered thermal load and mechanical vertical load. Exact horizontal load is not considered as the load applied to wheel. Therefore, above-mentioned loading methods could not be applied to estimate actual stress applied to wheel. Therefore, this study proposed safety estimation on wheel of freight car using heat-structural coupled analysis on the basis of loading condition and stress intensity factor.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.12
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• pp.887-895
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• 2018

This paper presents a braking model that can be used to design the safety distance of a train control system and a train braking system to increase the volume of traffic. For the braking model, a train set (electric multiple unit composed 6 cars) was tested. The factors that can affect the braking characteristics include the friction coefficient, braking pressure, and regenerative braking. The braking pressure was classified into service and emergency braking and reflected the characteristics of the vehicle. The external force acting on the running railway car was tested in accordance with KS R 9217, and the running resistance of the train is presented in the form of a polynomial. The dynamic behavior of the train running on a straight flat line was simulated using UM 8.3. The results were validated with experimental data, and the results were reasonable. With the validated model, a stopping distance was determined according to the initial braking speed and compared with the deceleration braking model. In addition, a safety distance for the train control system could be changed according to the frictional coefficient limits. These results are expected to be useful for analyzing the dynamic behavior of trains, and for analyzing various railway environments and improving the braking performance.