• Journal of Auto-vehicle Safety Association
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• v.8 no.1
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• pp.26-30
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• 2016

The steel road wheel on ventilation holes was cracked in the vehicle durability test. But the component durability test by uni-axial, CFT(Cornering Fatigue Test) and RFT(Radial Fatigue Test) had been satisfied. That is, the uni-axial component test could not forecast the crack of vehicle. Therefore this study developed the bi-axial test mode to reflect a vehicle condition(to reflect both vertical and lateral force simultaneously) based on real load data which was measured in Europe and China and developed CAE simulation too. It reproduced the cracks same as vehicle's and verified by bi-axial test machine in the LBF(Fraunhofer Institute for Structural Durability and System Reliability) durability research center in Germany. Finally this the durability CAE simulation by using HMC(Hyundai Motor Company)'s the bi-axial test mode predicts feasibly the steel wheel's durability performance before vehicle durability test.

• Transactions of the Korean Society of Automotive Engineers
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• v.7 no.9
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• pp.195-202
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• 1999

The kinematic and complicance characteristics of torsion beam axle is structurally related to the location and section profile of torsion beam and the span from body mounting point to wheel center. This paper presents the effect of section properties in torsion beam on the structural characteristics and roll behavior of suspension. The structural characteristics is on the maximum stress on the welding area of torsion beam and the roll behavior is on roll steer and roll-camber of suspension which are important for controllability and stability in cornering. Four factors are used for the section design of torsion beam, which are thickness , midline length, are inner radius, and sector half angle . Through the structural and quasi-static analysis made for six torsion beam axle models, it can be noticed that roll steer and the structural durability of suspension are closely related to warping constant and shear center in section properties of torsion beam.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.22 no.1
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• pp.112-118
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• 2013

Formula race car is generally recognized as a vehicle which is optimally designed for on-road race track with the regulations of race host bodies. Especially, the uprights of suspension system decisively have effects on the performance of cornering and stability of race car's driving performance, which are very important factors in the design of race car. This paper is a study of optimal upright design of F1800 grade formula race car which are normally used in professional race circuit in Korea. To design optimally the front upright of F1800 formula race car, Taguchi's orthogonal array, which is known for more useful method than full factorial design experimental method in cost and time, is used with CAE method such as FEM analysis. And the result of this paper shows that Taguchi's orthogonal array employed for this optimal design is very useful for designing the front upright of race car by minimizing its weight as well as keeping its safety factor as enough as designer wants in the view of quality, cost and delivery at the early design step.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2005.06a
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• pp.1371-1375
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• 2005

The paper has analyzed the influence of tire design variable on the tire Force and Moment (F&M) characteristics, especially by the belt angle, the Plysteer Residual Aligning Torque (PRAT) which is considered as one of the causing factors for the vehicle pull. To validate the tire FE model, the tire stiffness and the PRAT which can be derived from the simulation data have been compared with the experimental data of test machine. In addition to PRAT characteristic, the tire stiffness and cornering characteristics due to the belt angle have been investigated. The effects of drum's curvature on the PRAT have been also investigated using the tire FE model and the usefulness of the current drum type F&M test machine can be confirmed.

• Journal of the Korean Society of Industry Convergence
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• v.23 no.2_2
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• pp.163-171
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• 2020

The condition of tire tread is a key parameter closely related to the driving safety of a vehicle, which affects the contact force of the tire for braking, accelerating and cornering. The major factor influencing the contact force is tread wear, and the more tire tread wears out, the higher risk of losing control of a vehicle exits. The tire tread condition is generally checked by visual inspection that can be easily forgotten. In this paper, we propose the intelligent tire (iTire) system that consists of an acceleration sensor, a wireless signal transmission unit and a tread classifier. In addition, we also presents classification algorithm that transforms the acceleration signal into the frequency domain and extracts the features of several frequency bands as inputs to an artificial neural network. The artificial neural network for classifying tire wear was designed with an Multiple Layer Perceptron (MLP) model. Experiments showed that tread wear classification accuracy was over 80%.

• The Journal of Korea Robotics Society
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• v.15 no.2
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• pp.139-146
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• 2020

In this paper, the slope of the footplate is adjusted to compensate for the centrifugal force with a series elastic actuator (SEA) attached to the Segway's body to improve the cornering characteristics during turning. To ensure Segway's driving safety in the curvature motion, it is necessary to compensate for the centripetal force by tilting the footplate to generate inward force from gravity. When the footplate is tilted under the control of SEA, the vertical load on both wheels has been changed accordingly. The frictional force of the wheel has been changed by the change of the vertical force, which requires adjustment of driving torque to keep the curvature trajectory. That is, the driving torque has been controlled to keep the curvature trajectory considering the frictional force caused by the turning motion. Four SEAs are attached to the footplate to control the slope of the footplate and the real curvature motion has been demonstrated to verify the effects of SEAs in the high- speed curvature motion.

• Journal of the Korean Society for Railway
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• v.15 no.1
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• pp.1-8
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• 2012

Wheelset dynamic analysis is a key element to determine the degree of accuracy of railway vehicle dynamics. In this study, a three-dimensional wheelset dynamic analysis is presented in such a way that the precise wheel-rail contact analysis in three-dimension is implemented into the dynamic equations of a wheelset. A numerical procedure that can be used for the analysis of a wheelset dynamics when the wheel-rail two point contact occurs in a cornering maneuver is developed. Numerical solutions of the constraint equations and the dynamics equations of a wheelset are achieved by using Runge-Kutta method. The proposed wheelset dynamic analysis is validated by comparison against results obtained from VI-RAIL analysis.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.19 no.8
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• pp.8-14
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• 2020

In the air current pulverizing type grinding method, the blade wings fitted inside a casing are rotated at a high speed to generate a cornering air current, which facilitates the collision of materials with one another, leading to the pulverizing phenomenon. In contrast to mechanical grinding, grit pulverizing leads to fine grinding and less acid waste and degeneration of the material. Moreover, this approach prevents the loss of nutritional value, while allowing the milling grain to have an excellent texture. However, the existing air current pulverizing type machines consist of prefabricated blades, which cannot be rotated at a speed higher than 5,000 rpm. Consequently, the grinding process becomes time consuming with a low productivity. To overcome these problems, in this study, the shape and structure of the air current pulverizing type wings were optimized to allow rapid grinding at more than 8,000 rpm. Moreover, the optimal design for the ripening parts for the air current pulverizing type device was determined by performing a computational fluid dynamics analysis based on airflow analyses to produce machinery that can grinding materials to the order of micrometers.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.24 no.5
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• pp.568-575
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• 2015

A hand-made vehicle with a formula (VF-1) was designed and manufactured with the aim of realizing a lightweight and high-performance vehicle. The driver's body weight and stiffness of the frame were considered. The vehicle was equipped with a one-cylinder Exiv 250 engine with intake manifold potting for realizing weight reduction, high performance, and low cost. The suspension system for the formula was designed through the analyses and tests of vehicle motion and equipment. In a steering system, anti-Ackerman geometry was introduced to increase the transverse force during cornering. A full electric paddle shift system was adopted to decrease the braking distance. For protection against the distortion and warping of the frame, tungsten inert gas (TIG) welding technology was used.

• Wind and Structures
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• v.19 no.2
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• pp.113-144
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• 2014

Separation bubble and conical vortices on a large-span flat roof were observed in this study through the use of flow visualization. The results indicated that separation bubble occurred when the flow was normal to the leading edge of the flat roof. Conical vortices that occur under the cornering flow were observed near the leading edge, and their appearance was influenced by the wind angle. When the wind changed from along the diagonal to deviating from the diagonal of the roof, the conical vortex close to the approaching flow changed from circular to be more oblong shaped. Based on the measured velocities in the conical vortices by flow visualization, a proposed two-dimensional vortex model was improved and validated by simplifying the velocity profile between the vortex and the potential flow region. Through measured velocities and parameters of vortices, the intensities of conical vortices and separation bubble on a large-span flat roof under different wind directions were provided. The quasi-steady theory was corrected by including the effect of vortices. With this improved two-dimensional vortex model and the corrected quasi-steady theory, the mean and peak suction beneath the cores of the conical vortices and separation bubble can be predicted, and these were verified by measured pressures on a larger-scale model of the flat roof.