• International Journal of Automotive Technology
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• v.6 no.5
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• pp.475-481
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• 2005

This paper deals with the algorithm of estimating the longitudinal speed of a braking vehicle using measurements from an accelerometer and a standard wheel speed sensor. We evolve speed estimation algorithms of increasing complexity and accuracy on the basis of experimental tests. A final speed estimation algorithm based on a Kalman filtering is developed to reduce measurement noise of the wheel speed sensor, error of the tire radius, and accelerometer bias. This developed algorithm can give peak errors of less than 3 percent even when the accelerometer signal is significantly biased.

• Proceedings of the KSME Conference
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• 2003.04a
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• pp.1270-1276
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• 2003

This paper describes an analytical method for wheel wear prediction. The outputs from vehicle dynamic software are used to calculation the wheel wear. Two calculation examples are shown for a high-speed line and a conventional line. Through the comparison of two cases, we can see the wheel wear characteristics on the conventional line and the high-speed line. The conventional line has many curved tracks that cause severe wheel flange wear. The influences of curve radius on wheel wear are also described considering the operational performance of the high speed trainset. A method of calculation using contact patch work model is presented for determination of the evolution by wear railway wheels.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.2 no.4
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• pp.40-45
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• 2003

In this paper, to choose the optimum CBN wheel for Internal Grinding at LM Guide, among 7 types of CBN-wheels, the 2 types of CBN-wheels, which were the macrofracture CBN wheel and the microfracture CBN wheel, have been used, and the SCM420H have been used as the workpiece. The working conditions in the grinding experiments were depth-of-cut, table speed, and spindle speed for 4 types of the CBN grinding wheels, 2 types of the lubrications. By the experiments, the loading effect of the microfracture types of the CBN-wheel needed a short dressing interval and resulted in grinding wheel wear and bad surface roughness. However, a macrofracture type of CBN-wheel with the concentration of 100, CB120Q100V showed the best surface roughness quality at a low table speed for internal grinding at LM-guide.

• Journal of the Semiconductor & Display Technology
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• v.10 no.3
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• pp.35-42
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• 2011

This paper describes the characteristics of high speed grinding and the influence of wheel surface speed V and a grindability of the grinding materials. The various fine ceramics pieces was ground by metal and vitrified bonded diamond wheel. The surface roughness of fine ceramics(Zirconia($ZrO_2$), Silicon Carbide(SiC), Silicon Nitride($Si_3N_4$), Alumina($Al_2O_3$)) decreases from $0.05{\mu}m(R_{max})$ to $0.025{\mu}m(R_{max})$ when the wheel speed at grinding point increases the wheel speed. Relation between the temperature at grinding point and surface roughness was linear. Abrasive jet machining(AJM), a specialized from of shot blasting, is considered one of the most helpful micro machining methods for hard and brittle materials such as glasses and ceramics by constant pressure grinding.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.21 no.4
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• pp.84-90
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• 2022

In this study, the acceleration performance improvement was analyzed for a 2-speed transmission applied EV. An EV simulator was developed to analyze the EV acceleration performance. The EV simulator includes a load transfer model between the front and rear. Thus, the EV simulator can analyze the acceleration performance difference between the front-and rear-wheel drive EVs. From the simulation results, it is deduced that the acceleration performance can be improved by 7.96% for the front-wheel drive EV and 16.10% for the rear-wheel drive EV. The 2-speed transmission can improve the acceleration performance without decreasing its maximum velocity. Moreover, the 2-speed transmission can improve the acceleration performance of the rear wheel drive more than that of the front-wheel drive EV.

• Journal of Astronomy and Space Sciences
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• v.25 no.4
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• pp.481-490
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• 2008

Reaction wheel is one of the actuators for spacecraft attitude control, which generates torque by changing an inertial rotor speed inside of the wheel. In order to generate required torque accurately and estimate an accurate angular momentum, wheel speed should be measured as close to the actual speed as possible. In this study, two conventional speed detection methods for high speed motor with digital tacho pulse (Elapsed-time method and Pulse-count method) and their resolutions are analyzed. For satellite attitude maneuvering and control, reaction wheel shall be operated in bi directional and low speed operation is sometimes needed for emergency case. Thus the bias error at low speed with constant acceleration (or deceleration) is also analysed. As a result, the speed detection error of elapsed-time method is largely influenced upon the high-speed clock frequency at high speed and largely effected on the number of tacho pulses used in elapsed time calculation at low speed, respectively.

• Journal of the Korean Society for Railway
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• v.5 no.3
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• pp.167-173
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• 2002

The influence of thermal stress at tread breaking in Korean High Speed Train wheel was investigated using the coupled thermal-mechanical analysis technique. The mechanical load or wheel-rail contract load and braking load were considered during FEM analysis. During the stop braking, the effect of mechanical stress on the combined stress is relatively larger than that of thermal stress in the rim of wheel. However, the effect of thermal stress is relatively larger than that of mechanical stress in the plate of wheel. When 300% of the block force was applied, the maximum von Mises stress of 61.0 MPa was found at the outside plate around 400 mm far away from the wheel center.

• Journal of the Korean Society for Railway
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• v.10 no.5
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• pp.473-479
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• 2007

Lateral vibration at the tail of KTX train was found during the acceptance test. In order to settle the problem of lateral vibration, the wheel conicity was changed 1/40 to 1/20. However, we should evaluate the running safety of vehicle with 1/20 wheel conicity because modification of wheel conicity may cause the running performance to be worse and critical speed to reduce. In this paper, we calculate critical speed of KTX bogie as wheel conicity increase and analyze the running safety for KTX that has 20 car trainset formation using VAMPIRE. and compare with the test results of KHST to validate analysis results on high speed line. A analysis results show that critical speed of 0.3 wheel conicity is over 375km/h and curving performance of 1/20wheel conicity is better than 1/40. Also, we examinate the running performance of KTX to check out possibility to increase speed of KTX on conventional line. A analysis results show that it is possible to increase up to 10% the speed of KTX on tangent line but KTX on a curved line should be operated with the speed of conventional train.

• Journal of the Korean Society for Precision Engineering
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• v.27 no.8
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• pp.13-19
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• 2010

A design method of railway wheel profile with objective function of equivalent conicity considering wheel dimension constraint, two points contact problem between wheel and rail was proposed. New design method shows good results. New wheel profile generated from optimization process shows better dynamic performance compared with initial profile as the purpose of wheel profile design. And to verify the design method with testing the stability of new wheel profile, we conducted a critical speed test for new wheel profile using scale model applied scaling method of railway vehicle dynamics. The result of critical speed test show good agreement with that of numerical analysis. From the above results, it is seen that the design method with objective function of equivalent conicity is feasible and it could be applied to design new wheel profile efficiently.

• Proceedings of the Korean Society for Agricultural Machinery Conference
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• 1996.06c
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• pp.469-477
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• 1996

In order to maintain a constant ratio between the ground wheel and fed shaft of planters, a feedback control unit was designed to drive the feed shaft in proportional to the ground speed. The fifth wheel was used as a ground speed sensor for the control unit. Using this control unit a feed shaft driving system was developed and tested both in the laboratory and field to evaluate it performance . The test results showed that the system drove the feed shaft in proportional to the ground speed in the normal planting speed range of 0.5 -0.8m/s with an error of less than 5%.