• The Journal of the Acoustical Society of Korea
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• v.16 no.1
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• pp.54-59
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• 1997

The vehicle vibrations result from the exciting forces which are caused by air resistance, engine firing, tire mass unbalance and tire uniformity. Especially, the shake and shimmy phenomena in the steering system are closely related to the vehicle vibration, the tire unbalance, and the tire uniformity. This study presents the shimmy phenomena due to the tire mass unbalance and the tire uniformity in order to investigate their effects.

• Journal of Auto-vehicle Safety Association
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• v.12 no.1
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• pp.6-14
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• 2020

Personal mobility, which was used exclusively for leisure activities, has recently been used as a means of transportation, and it is expected to increase its role as the next generation transportation. Sales of personal mobility are increasing rapidly, but the problem is that traffic accidents are also increasing. In this study, human body injury caused by various collisions between electric wheel users and road users that occur on bicycle or pedestrian roads mainly used by personal mobility is analyzed through collision analysis and collision risk analysis. In the case of the collision accident for electric wheel, it is analyzed that the road users are more likely to be injured on the pedestrian road than the bicycle road. In addition, the head hit each other or fall and hit the floor caused severe head injury.

• Tribology and Lubricants
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• v.16 no.3
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• pp.173-181
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• 2000

Friction, wear and corrosion characteristics of various MoS$_2$ bonded film lubricants were investigated to apply them to automotive wheel joints. MoS$_2$ bonded film lubricants were formulated by combinations of several additives and binders, and they were coated onto the pre-treated surfaces of specimens. Friction and wear characteristics were evaluated with Falex pin & vee-block test and LFW-1 block-on-ring test. For the corrosion resistant characteristics of the films, salt solution spray corrosion tests were performed. Results showed that MoS$_2$ bonded films containing both inorganic and organic corrosion-resistant additives yielded a synergy effect on anti-corrosion resistance. Also, binders having the better water-proof and thermal stability showed the lower friction and higher corrosion resistance.

• Journal of Auto-vehicle Safety Association
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• v.14 no.4
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• pp.16-20
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• 2022

Accurate state estimation is important for autonomous driving. However, the estimation error increases in situations that a lot of longitudinal slip occurs. Therefore, this paper presents a vehicle state estimation method using an Extended Kalman Filter. The filter estimates the states of the host vehicle robust to wheel slip. It utilizes the measurements of the four-wheel rotational speeds, longitudinal acceleration, yaw-rate, and steering wheel angle. Nonlinear measurement model is represented by Ackermann Model. The main advantage of this approach is the accurate estimation of yaw rate due to the measurement of the steering wheel angle. The proposed algorithm is verified in scenarios of autonomous emergency braking (AEB), lane change (LC), lane keeping (LK) using an automated vehicle. The results show that the proposed algorithm guarantees accurate estimation in such scenarios.

• Journal of the Korean Institute of Gas
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• v.19 no.3
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• pp.49-53
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• 2015

The purpose of this paper is to study and analyze the failure examples for fire by friction on clutch, manual transmission and tire system in a car. In the first example, the driver took the pedal with foot to act the clutch. But the clutch disk did not return from flywheel by leakage of clutch hydraulic line. The heat was produced between clutch disk and flywheel by surface contacting. As a result, it was produced the fire by oil sludge sticked with transmission. In the second example, the transmission system was operated to transfer power of engine by contacting with gear and gear. But, as if the oil of transmission was caused the oil insufficiency because of leaking by crack of transmission case, it found the fact that was produced the fire by deposit material on transmission case. In the third example, when the car's driver continuously pushed an accelerator pedal for escaping from dry pit, the tire took the heat by the friction force between tire and surface of road. As a result, it became the direct cause for the fire. Therefore the driver must manage not to produce the fire with friction parts by heating during running.

• Korean Journal of Materials Research
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• v.9 no.12
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• pp.1252-1262
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• 1999

The effect of microstructures on the strength-flangeability of Nb bearing hot-rolled high strength steel was investigated in order to improve the strength-flangeability of conventional TS 580MPa grades HSLA steel for the automotive wheel disc. The low temperature coiling method using 3-step controlled cooling pattern after hot rolling was effective to produce the Nb-bearing high strength steel with the polygonal ferrite and bainite duplex microstructures. It was suggested that the suppressed precipitation of grain boundary cementites and the decreased hardness difference between ferrite matrix and bainite cause the excellent stretch-flangeability of ferrite-bainite duplex microstructure steel. Therefore, the formation and propagation of microcracks were suppressed relative to the conventional HSLA steel with ferrite and pearlite microstructure. In addition, the elongation was improved as compared with that of hot-rolled steel sheets using conventional early cooling pattern because the volume fraction of polygonal ferrite was increased.

• Transactions of the Korean Society of Automotive Engineers
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• v.18 no.3
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• pp.1-7
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• 2010

Recently, the vehicle driving device has been designed for driver's convenience. Especially, the automobile industry develops the vehicle using the joystick instead of steering wheel from the concept car. The biggest strength of using the joystick is that the driver feels less workload and fatigue than when the driver uses steering wheel. However, this kind of study still needs more research and experiments for more accurate result. Therefore, this research evaluated workload according to the driving device by the survey and the measurement of physiological signal. The reason not only using the survey also using the measurement of physiological signal is to support the result of the survey which is not enough to bring the accurate result. There were tow different kinds of methods to carry out this research; SWAT (Subjective Workload Assessment Technique) for the survey and the biopac equipment for the measurement of physiological signal. Furthermore, previously established driving simulator, GPS (Global Positioning System), and Seoul-Cheonan virtual expressway DB were used for the experiment. As the result of the experiment with 13 subjects, it was certain that using joystick device brings less workload and fatigue to the drivers than using steering wheel following both methods-the survey and the measurement of physiological signal. Also, it confirmed the significant result from the SPSS (Statistical Package for the Social Sciences) statistics analysis program.

• Transactions of the Korean Society of Automotive Engineers
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• v.15 no.4
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• pp.10-16
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• 2007

A rubber seal for wheel bearing which has been mainly applied to car wheel supporting device is required to have both high sealing performance and drag torque. Because of severe operational conditions like infiltration of mud or splashed water, the importance of rubber seal which is aimed for leakage prevention of grease and effective blocking of foreign substances has been increasing continuously. The sealing performance of this seal depends on several factors such as materials of seal, friction conditions of contact regions and geometry of seals and so on. We have focused on the effects of geometric characteristics such as the angle of main lip, interference between lip edge and inner metallic ring. In this study, the optimization of geometric variables was performed using the finite element analysis. For the sake of finite element analysis, uniaxial tensile tests were conducted and several constants for Mooney-Rivlin's equation were obtained. According to the results of this study, mock-up bearing was made. To verify this study, drag torque and mud spray test were preformed.

• Journal of the Korean Institute of Gas
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• v.21 no.2
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• pp.26-31
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• 2017

The purpose of this paper is to study for turbocharger system in a vehicle of diesel engine. The first example, it certified the fact that a car engine is not to accelerate by clogged the exhaust tube as the turbine was damaged because of turbine wheel broken. The a vehicle with turbocharger must to stop engine operation after maintaining the appropriate idle revolution as it can be the sticking phenomenon if the operator immediately stop the engine being high revolution. The second example, it knew the phenomenon of acceleration faulty that the rod of VGT actuator that operating the turbocharger adhered with the bracket of VGT. The third example, it confirmed the power insufficiency phenomenon when driving by of alternator resistor and fan intercooler fan relay connector mistaken assembly. Therefore, the operator have to scrutinize manage no the failure of turbocharger system.

• Transactions of the Korean Society of Automotive Engineers
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• v.24 no.5
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• pp.581-587
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• 2016

Braking is a basic and an important safety feature for all vehicles, and the final braking performance of a vehicle is determined by the vehicle's ABS performance and tire performance. However, the combination of excellent ABS and tires will not always ensure good braking performance. This is due to the fact that tire performance has non-linearity and uncertainty in predicting the repeated increase and decrease of wheel slip when activating the ABS, thus increasing the uncertainty of tire performance prediction. Furthermore, existing studies predicted braking performance after using an ABS that used a wheel slip control as a controller, which was different from an actual vehicle's ABS that controlled angular acceleration, therefore causing a decrease in the prediction accuracy of the braking performance. This paper reverse-designed the ABS that controlled angular acceleration based on the information on brake pressure, etc., which were obtained from vehicle tests, and established a braking performance prediction analysis model by combining a multi-body dynamics(MBD) vehicle model and a magic formula(MF) tire model. The established analysis model was verified after comparing it with the results of the braking tests of an actual vehicle. Using this analysis model, this study analyzed the braking effect by vehicle factor, and finally designed a tire that had optimized braking performance. As a result of this study, it was possible to design the MF tire model whose braking performance improved by 9.2 %.