• The Transactions of the Korean Institute of Electrical Engineers P
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• v.65 no.2
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• pp.77-83
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• 2016

The electric quality of train is represented by voltage and current harmonics at PT(Ratio 25,000/15/[V]) which is located between pantograph and primary winding of train transformer. In this paper, voltage and current harmonics were measured on the test EMU(electric multiple unit)train with maximum speed of 180km/h in existing railway lines(chungbuk, Taeback, Honam). As a results of test, it is found that the electric quality of train depends on the mostly operation conditions which is accelerating mode and braking mode on each sections. Voltage THD is above all 3[%] and current harmonics is monitored from lowest Harmonic to highest Harmonic in case of accelerating mode. But, highest current harmonics is not monitored in case of breaking mode. The results in this paper can help to stabilize the power device and power converter of the test EMU train.

• Proceedings of the KSR Conference
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• 2011.10a
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• pp.685-692
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• 2011

DC/DC switching power converters produce DC output voltages from different DC input sources. The converters can be used in regenerative braking of DC motors to return energy back in the supply, resulting in energy savings for the systems containing frequent stops. The current mode DC/DC converter is composed of a PWM (pulse width modulation) controller, a MOSFET, and inductor, etc. Pulse width modulation is applied to control and regulate the total output voltage. It is shown that the variation of threshold voltage at MOSFET and the offset voltage increase caused by radiation effects make the PWM pulse unstable. In the PWM operation, the missing pulses, the changes in pulse width, and a change in the period of the output waveform are studied by simulation program with integrated circuit emphasis (SPICE) and experiments.

• 제어로봇시스템학회:학술대회논문집
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• 1997.10a
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• pp.357-360
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• 1997

This paper presents a new anti-lock brake system(ABS) using electro-rheological(ER) valve actuators for the wheel slip control. The hydraulic dynamic model of the automotive brake system is formulated by incorporating electric field-dependent Bingham properties of ER fluid obtained experimentally. The brake system designed by this hydraulic model is able to control wheel slip by controlling the intensity of electric field which tunes the braking torque. The control fields of the ER valve to command desired wheel slip are determined by a sliding mode controller. A comparison between the proposed brake system and the conventional brake system is made by providing with computer simulations of vehicle motions under ABS performance requirement condition.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2007.05a
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• pp.1125-1130
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• 2007

This paper presents a maneuver analysis of a full-vehicle featuring electrorheological (ER) suspension and ER brake. In order to achieve this goal, an ER damper and an ER valve pressure modulator are devised to construct ER suspension and ER brake systems, respectively. After formulating the governing equations of the ER damper and ER valve pressure modulator, they are designed and manufactured for a middle-sized passenger vehicle, and their field-dependent characteristics are experimentally evaluated. The governing equation of motion for the full-vehicle is then established and integrated with the governing equations of the ER suspension and ER brake. Subsequently, a sky-hook controller for the ER suspension and a sliding mode controller for the ER brake are formulated and implemented. Control performances such as vertical displacement and braking distance of vehicle are evaluated under various driving conditions through computer simulations.

• 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.

• Aerospace Engineering and Technology
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• v.7 no.1
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• pp.8-14
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• 2008

Basic characteristics of wheel brake accumulator for aircraft is studied. Wheel brake accumulator maintains the braking pressure for parking mode, and also it supplies the hydraulic pressure to the wheel brake system for emergency mode. The design requirements of wheel brake accumulator are analyzed and the initial sizing is conducted. A wheel brake accumulator consists of a cylinder and a brake control module, and the basic configuration and detail components are presented. Again, structural static analysis of vessel is performed with NASTARN/PATRAN for preliminary design.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.31 no.12
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• pp.1131-1138
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• 2007

This paper studies experimentally on the building-up process for the amplitude of a commercial truck vibration induced by brake judder. A front axle drum equipped with a drum brake system is utilized for this experiment. A brake dynamo test, a real vehicle ride test and a real vehicle braking test are performed for the analysis of brake judder. The brake dynamo test measures judder by applying brake chamber pressures of 1, 2 and 3 bar at initial brake pad temperatures of $100^{\circ}C$ and $150^{\circ}C$. In order to assess the vertical acceleration at the front axle, the real vehicle ride test on a straight test road with velocities of 20, 40, 60 and 80 km/h is performed. The real vehicle braking test is carried out at the deceleration rate of 0.2g from a velocity of 90km/h for evaluating the vertical, lateral and longitudinal accelerations both at the front axle and at the cab floor under the driver's seat. The magnitudes and frequencies of the measured peak accelerations from the brake dynamo test, the real vehicle ride test and the real vehicle braking test are comparatively analyzed. This paper shows that the vibration produced by brake judder is built up due to the brake system's peak acceleration frequency being close to the vehicle ride mode's frequency.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.37 no.4
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• pp.330-336
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• 2004

To meet the increasing demand from various fishing fields for training of fishing equipment operators, a fishing winch simulator was designed to train maritime students in the correct and safe operation of hydraulic winches under various load conditions related to fishing operations. The aim of this study is to describe the basic dynamic characteristics of the newly developed hydraulic fishing winch simulator and particularly to analyze the mechanical responses produced on the winch operation controls. The winch simulator consists of two winch units, a computer control and data acquisition system, a control consol and other associated mechanisms. When one winch is in hauling mode, the other one will always be in loading mode. The revolution speed of the hauling winch was controlled by a proportional directional control valve, and the braking torque of the loading winch was controlled by a proportional pressure control valve. The simulation experiments indicated that the dynamic characteristics of the hauling winch followed the braking response characteristics of the loading winch. The tests also showed that the warp speed and tension linearly depend on the pressure differential across the motor of the loading winch controlled by operating the proportional pressure control valve during the hauling operation. The experience gained from various training courses showed that the fishing winch simulator was very realistic and it was valuable for training novice winch operators. The results of the winch simulation exercise were recorded and used to evaluate the training on the operation and handling of the winch system. From these test results, we concluded that the tension acting on the warp during hauling operations can successfully be simulated by controlling the pressure differential across the motor with step changes of the control input signal to the proportional pressure control valve of the loading winch.

• Journal of Auto-vehicle Safety Association
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• v.10 no.3
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• pp.38-44
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• 2018

Conventional brake system was used for passenger cars and SUV for a long time. However, the high performance brake system has strongly required because of increase of engine power and customer's favorites etc. In this paper, a new high performance brake system for Europe was proposed. For this system, the high performance caliper and disc were newly developed. The superiorities of the developed high performance brake system were verified via heat capacity, hydraulic stiffness, corrosion and harsh braking mode test. Also, the high performance caliper and disc for the light-weight were applied to AL-Alloy and can obtain the weight reduction effect of 2.9 kg per vehicle. Finally, a developed high performance brake system is expected to be used for realization of the high performance at the same platforms.

• Proceedings of the KIPE Conference
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• 2001.10a
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• pp.457-461
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• 2001

Advantages of switched reluctance motor(SRM) drives make it an attractive candidate for replacing adjustable speed ac and dc drives in both industrial and consumer applications. Furthermore, a simple, low cost and robust SRM drive can be efficiently operated in the hostile environment of an automobile. Generally, the speed control of SRM has a large step change or large torque reference, the output of its PI controller is often saturated. When this happens, the integral state is not consistent with the SRM input, while may give rise to the windup phenomenon. This paper proposes anti-windup control method for SRM speed control system by hysteresis current controlled asymmetry bridge converter. The experimental results show that the speed response has much improved performance, such as a small overshoot and fast settling time at the acceleration and particulary deceleration period with braking mode.