• 한국안전학회지
• /
• 제22권2호
• /
• pp.8-14
• /
• 2007

In this study, tensile and fatigue crack propagation tests machined from actual wheels were performed. FEM analysis also was performed on the crack that was assumed to be 15 mm in depth under the wheel tread surface. The stress intensity factors K I and K II at the crack tip under the stress($P_{max}=911.5MPa$) due to a rolling contact were analyzed for crack growth characteristics. As a result, the perpendicular crack was found to be more dangerous compared to the parallel one. It is found that in the wheel fatigue crack, parallel to the wheel tread surface, the crack with its length 2a = 2.4mm starts to propagate due to the fact that the effective stress intensity factor access to the threshold stress intensity factor($K_{th}=16.04MPa{\sqrt{m}}$) of the wheel.

• 한국정밀공학회:학술대회논문집
• /
• 한국정밀공학회 2006년도 춘계학술대회 논문집
• /
• pp.311-312
• /
• 2006

In this paper, steering systems for mobile robot with permanent magnet wheels are discussed. The mobile robot with permanent magnet wheels can have three different types of steering and driving configurations; two-wheels, three-wheels, four-wheels. By a Two-WD(Wheel Driving) system, driving and steering characteristics are controlled by ratio of each wheel speeds. Three-WD system is steered by a front wheel and driven by rear wheels. Four-WD system has better stability than two wheel system. Usually the permanent magnet wheel has nearly none slip. Thus turning radius of the mobile robot with three-WD and four-WD System will be increased and the steering and driving system will be complicated. To solve this problem, two magnet wheels with two dummy wheels are used in this study. fuming radius of the developed mobile robot is small and the structure of the robot is simple. It is possible to move forward, backward, to turn left and right, and to rotate freely with two-WD. This study proved that two-WD system is very suitable fur the mobile robot with permanent magnet wheels.

• International journal of advanced smart convergence
• /
• 제11권2호
• /
• pp.219-225
• /
• 2022

Recently, the popularization of personal mobility(PM) has made it possible to see many electric scooters. The energy source of personal transportation used by the general public and the disabled can be seen as environmentally friendly as electricity. Personal transportation means are divided into small electric vehicles because they use electric energy, and they are being treated as new models by automobile manufacturers in each country and spurring development. On the other hand, personal transportation means may cause various types of traffic accidents as they travel between roads and a human walk. In order to prevent such accidents, it is judged that the enactment of laws on the establishment of specifications for electric scooters, which are personal transportation means, and the method of restricting road operation should be given priority. The electric scooter is basically different from the conventional vehicle. The steering shaft of the steering system applied to the electric scooter one to two is possible. 1 to 2 the front-wheel under the steering column is used. It is classified according to the number of wheel installed at the electric scooter is the vehicle body into 2 wheel - electric scooter, and 3 wheel - electric scooter and 4 wheel - electric scooter. In this study, we propose a steering shaft design model that can be applied to an electric scooter, one of personal transportation means. A design model for 1-shaft steering and 2-shafts steering that can be applied to electric scooters is proposed. In addition, we have produced the prototypes for the commercialization of the proposed models, and reviewed the pros and cons of the manufactured prototypes and models.

• 한국재료학회:학술대회논문집
• /
• 한국재료학회 1995년도 추계 학술발표 강연 및 논문개요집
• /
• pp.113-114
• /
• 1995

• 한국자동차공학회논문집
• /
• 제20권1호
• /
• pp.46-52
• /
• 2012

A PAEM(Pneumatic Active Engine Mount) system has been developed to improve NVH performance of a SUV in idle state. Control objective to attenuate the vibration of a vehicle should be determined prior to the design of control algorithm. This study presents the correlation analysis of output variables of PAEM system by means of TPA(Transfer Path Analysis) using experimental data obtained by vehicle test. The analysis results show that the vibration of vertical direction is more serious than those of longitudinal and lateral direction of the vehicle, and that the correlation between the vibration of front seat rail and that of steer wheel is highest. In conclusion, the vibrations of front seat rail and steer wheel in vertical direction should be considered as the control objectives of the PAEM.

• 한국자동차공학회논문집
• /
• 제19권2호
• /
• pp.72-77
• /
• 2011

In this paper, we propose effective diagnosis algorithm for hub bearing fault in driving vehicle using acceleration signal and wheel speed signal measured in hub bearing unit or knuckle. This algorithm consists of differential, envelope and power spectrum method. We developed diagnosis system for realizing proposed algorithm. This system consists of input device including acceleration sensor and wheel speed sensor, calculation device using Digital Signal Processor (DSP) and display device using Personal Digital Assistant (PDA). Using this diagnosis system, a driver can see hub bearing fault(flaking) from the vibration in driving vehicle. With early repairing, he can keep good ride feeling and prevent accident of vehicle resulting from hub bearing fault.

• 한국자동차공학회논문집
• /
• 제22권4호
• /
• pp.89-97
• /
• 2014

As the digital control technologies in automotive industry have advanced, electronic control units(ECUs) play a key-role to improve system performance. Transmission control unit(TCU) is a shifting controller for automatic transmission of which major functions are to determine the shift and manage the shifting process considering the various sensor signal on transmission and driver's commands. As with any ECU in vehicle, TCU performs complex algorithms such as shift control, diagnostic and failsafe functions. However, firmware design analysis is hardly possible by the reverse engineering due to code protection. Transmission simulator is a hardware-in-the-loop simulator which enables TCU to work in normal mode by simulating the electrical signal of TCU interface. In this research, diagnosis and failsafe algorithm implemented on commercialized TCU is analyzed by using the transmission simulator that is developed for wheel loader construction vehicle. This paper gives various experimental results on the proportional solenoid current trajectories for different operating modes, error detection criterion and limphome mode gears for all the possible cases of clutch malfunction. The derived results for conventional TCU can be applied to the development of inherent TCU algorithms and the transmission simulator can also be utilized for the test of TCU to be developed.

• International Journal of Precision Engineering and Manufacturing
• /
• 제4권4호
• /
• pp.32-38
• /
• 2003

An analytical model of the interference phenomena in the centerless grinding process is developed to investigate their effects on the roundness profile of a centerless ground workpiece. In this work, the regulating wheel and work-rest blade interferences are modeled as a single point contact. The grinding wheel interference is modeled as multiple points contact because material removal is determined by the duration of contact. The computer simulation results show good agreement with the experimental data. From this work, the existence and effects of the interference phenomena in the centerless grinding process are found.

• 대한기계학회논문집A
• /
• 제40권6호
• /
• pp.595-602
• /
• 2016

자동차용 휠 베어링은 회전운동을 전달하고 차량의 무게를 지지해주는 중요한 부품이다. 최근 $CO_2$ 배출가스 저감과 연비 규제에 따라서 자동차 경량화 및 소형화 요구는 점점 증가하고 있고, 이에 부응하여 베어링의 수명 평가기술은 더욱 그 필요성이 증가하고 있다. 휠 베어링의 내구수명은 고려해야 할 인자들이 매우 다양하며 이들이 서로 복잡하게 연관되어 있으므로 수명을 예측하는 것이 쉽지 않다. 본 논문에서는 자동차용 휠 베어링의 수명에 영향을 끼치는 많은 인자들 중에서 작동하중과 회전속도를 변화시키면서 수명을 시험하였고, 이를 ISO 국제표준에서 제안하는 이론수명인 기본정격수명과 보정정격수명 결과와 비교하였다. 이들 수명을 비교한 결과, 기본정격수명과 보정정격수명 모두 시험수명과 차이가 존재하며, 기본정격수명 보다 보정정격수명이 시험수명을 상대적으로 잘 예측함을 알 수 있었다.

• 한국자동차공학회논문집
• /
• 제24권5호
• /
• pp.581-587
• /
• 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 %.