• Transactions of the Korean Society of Automotive Engineers
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• v.12 no.2
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• pp.175-181
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• 2004

Analysis of brake characteristics has progressed rapidly in recent years, as computer techniques have developed. However, there are many problems in predicting braking characteristics, due to the numerous design variables of the brake system. Therefore, a synthetic braking performance analysis is required for all brake system parts such as master cylinder, booster, control valve and split system. In this paper, a program which can analyze braking performance such as force distribution, braking efficiency, pedal force and pedal travel, is presented. The preprocessor of the program helps users prepare input files through a dialog box. An additional postprocessor makes the graph presentation of solved results. Also, a simple example problem is applied to show the usefulness of the presented program.

• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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• 2002.10b
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• pp.387-388
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• 2002

A Brake device for the high-speed impacting object is designed using an axial crushing of thin-walled metal cylinder, Thickness of the cylinder is increased smoothly from the impacting end to the fixed end, resulting in the truncated cone shape. Truncated cone shape ensures that plastic hinges are formed sequentially from impacting end. This increases the reliability of brake device working. Computational and real experiments were performed to verify the effects of conical angle. Results indicate that undesirable sudden rise of crushing load can be prevented by applying appropriate conical angle.

• Transactions of Materials Processing
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• v.3 no.2
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• pp.178-188
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• 1994

A design methodology is applied for manufacturing a disk-brake piston component. The design criteria are the limit drawing ratio and the forging load within the available press limit. Also, the final product should not have any geometrical defect. The rigid-plastic FEM has been applied to simulate the conventional four stage manufacturing processes, which include deep drawing and forging process. Simulation of one stage process from a selected stock to the final product shape is performed for generating information on additional requirements for metal flow. Two stage forming processes with different punch corner and nose geometries are also simulated to identify the possible best solutions. Finally, the best manufacturing process is selected, which is using a hemispherical punch int he deep drawing process.

• 제어로봇시스템학회:학술대회논문집
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• 1991.10a
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• pp.962-967
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• 1991

A counter balance valve is used as one part of hydraulic motor brake system. The function of this valve is to protect over-run or free falling of inertia load. But occasionally the brake system with counter balance valve makes some undesirable problems such as pressure surges or vibrations. In this study, for the purpose of easy estimation about dynamic characteristics of hydraulic system including counter balance valve, precise formulation describing fluid dynamics and valve dynamics under various boundary conditions were made. Dynamic characteristics were analysed by numerical integration using Runge-Kutta method, because the equations in this circuit with counter balance valve contain various nonlinear terms. Propriety of this analysis method is verified by experiment. For the purpose of obtaining fundamental data for preventing instability, this study experimented the effects of the spool taper, spring constant, cylindrical choke. And we developed double acting brake system integrated counter balance valve.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.8 no.4
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• pp.34-40
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• 2009

The effect of frictional factors on thermal stress and deformation volume of motorcycle brake disk was studied by using a disk-on-pad type friction tester. It has an effect on the frictional factor such as applied load, sliding speed, sliding distance and number of ventilated disk hole. However, it is difficult to know the mutual relation of these factors. In this study, thermal stress and deformation volume by using design of experiment with 4 elements were investigated for thermal analysis with regression analysis. Thermal stress and thermal deformation are obtained by the application of temperature from mechanical test. From this study, the result showed that the motorcycle brake disk with ventilated hole 3 had the most excellent thermal stress and deformation volume. The regression equation had a trust rate of 95% for the prediction of thermal stress and deformation volume of motorcycle brake disk was composed.

• 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 Aerospace System Engineering
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• v.12 no.2
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• pp.7-14
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• 2018

In this study, a new check valve was studied to improve the load pressure of a brake system with a small piezoelectric-hydraulic pump. During the pressurization process, the steady-state pressure at the load is affected by the ratio of the cross-sectional area of the check valve the chamber pressure and load pressure. Since the flow path cover of the check valve is made wider than the cross-sectional area of the output flow to prevent backflow, a method of reducing the area ratio is proposed for a higher load pressure by mounting an additional mass to a thin plate spring type check valve. To identify the effect of mounting an additional mass to the existing check valve on the load pressure, a simple brake system with a small piezoelectric-hydraulic pump was modeled using a commercial code AMESim. The AMESim modeling was verified by comparing the simulation results with the experimental results of the pump the existing check valve. The additional mass was added to the verified AMESim modeling and higher load pressure was able to be obtained through simulation. The 35% performance improvement in load pressure identified by carrying out pressurization test of the brake system after adopting the new check valve the small piezoelectric-hydraulic pump.

• The Transactions of the Korean Institute of Power Electronics
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• v.21 no.5
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• pp.396-403
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• 2016

Usually, large-sized buses and trucks have a very high load. In addition, frequent braking during downhill or long-distance driving, causes the conventional method using the brake friction to have a problem in safety because of brake fade and brake burst phenomenon. Auxiliary brakes dividing the braking load is essential. Hence, environment-friendly auxiliary brakes, such as contactless brake rather than the engine auxiliary brake system are needed. A study aimed at improving the energy efficiency by recharging electric energy with changing mechanical to electrical energy that occurs when braking is actively in progress. In this paper, the voltage control method is utilized to recover the electric energy generated in the electromagnetic retarder instead of the eddy current. To regenerate the braking energy into the electrical energy, the resonant L-C circuit is configured in the retarder. The voltage generated in the retarder is simply modeled as a transformer. However, retarder voltage control in this paper is simulated by modeling the induction generator because this induction generator modeling is more practical than transformer modeling. The changes in the voltage of the resonance circuit, which depends on the switch pulse duration of the control device, were analyzed. A PI controller algorithm to control this voltage is proposed. The feasibility of modeling retarder and voltage controller are shown by using MATLAB Simulink in this paper.

• Journal of Ocean Engineering and Technology
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• v.23 no.4
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• pp.69-77
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• 2009

Structural analysis of a brake shoe for commercial vehicle was performed using finite element method. Since the strength of a brake shoe is affected by the magnitude and distribution shape of the contact pressure with the drum, the contact pressure between the shoe friction material and drum was calculated using a 2-Dimensional non-linear contact analysis in a state. And the brake was actuated by input air pressure and the drum of it was calculated both stationary and dynamic based on forced torque applied to the drum during the static state analysis. The results of the above analysis were then used as the load boundary conditions for a 3-Dimensional shoe model analysis to determine the maximum strain on the shoes. In the analysis model, the values of tensile test were used for the material properties of the brake shoes and drum, while the values of compression test were used for the friction material. We assumed it as linear variation, even though the properties of friction material were actually non-linear. The experiments were carried out under the same analysis conditions used for fatigue test and under the same brake system which equipped with a brake drum based on the actual axle state in a vehicle. The strains were measured at the same locations where the analysis was performed on the shoes. The obtained results of the experiment matched well with those from the analysis. Consequently, the model used in this study was able to determine the stress at the maximum air pressure at the braking system, thereby a modified shoe model in facilitating was satisfied with the required endurance strength in the vehicle.

• Transactions of Materials Processing
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• v.23 no.2
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• pp.88-94
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• 2014

The under-drive brake piston is an essential part in the automatic transmissions of automobiles. This component is manufactured by forging after blanking from S55C plate with a thickness of 6mm. It is difficult to design the plate forging process using a thick plate approach since there will be limited material flow as well as large press loads. Furthermore, the under-drive brake piston has a complex shape with a right angle step, which often results in die unfill and abrupt increase in press load. To overcome these obstacles, a separate die for filling material sufficiently to the corner of the right angle step is proposed. However, this approach induces an uncontrolled workpiece surface between the dies, resulting in flash. This excess flash degrades the tool life in the final machining after cold forging as well as increases the cycle time to obtain the net-shape of the part. In the current study, we propose an optimum process design using a conventional die shaped with the benefit of finite element analysis. This approach enhanced the process efficiency without sacrificing the dimensional accuracy in the forged part. As the result, the optimum plate forging process was done with a two stage die, which reduces weight of by 6% compared with previous process for the under-drive brake piston.