• Journal of Power Electronics
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• v.16 no.4
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• pp.1324-1335
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• 2016

This article explores the speed regulation problem of permanent magnet synchronous motor (PMSM) systems subjected to unknown time-varying disturbances. A continuous sliding mode control (CSMC) technique is introduced for the speed loop to enhance the robustness of PMSM systems and eliminate the chattering phenomenon caused by high-frequency switch function in the conventional control law. However, the high control gain of the CSMC law in the presence of strong disturbances leads to large steady-state speed fluctuations for PMSM systems. In many application fields, PMSM systems are affected by time-varying disturbances instead of constant disturbances. For example, electric bicycles are usually affected by changing environmental disturbances, including wind speeds, road conditions, etc. These disturbances may be in the form of constant, ramp, and parabolic disturbances. Hence, a generalized proportional integral (GPI) observer is employed to estimate these types of disturbances. Then, the disturbance estimation method and the aforementioned CSMC method are combined to establish a composite sliding mode control method called the CSMC+GPI method for the speed loop of PMSM systems. Contrary to the conventional sliding mode control technique, the proposed method completely eliminates the chattering phenomenon caused by the switching function in the conventional control law. Moreover, a small control gain for the CSMC+GPI method is chosen by feed-forwarding estimated values to the speed controller. Hence, the steady-state speed fluctuations are small. The effectiveness of the proposed control scheme is verified by simulation and experimental result.

• Safety and Health at Work
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• v.6 no.2
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• pp.104-113
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• 2015

Background: Given the long hours on the road involving multiple and interacting work stressors (i.e., delivery pressures, irregular shifts, ergonomic hazards), commercial drivers face a plethora of health and safety risks. Researchers goal was to determine whether and to what extent long-haul trucker work schedules influence sleep duration and quality. Methods: Survey and biometric data collected from male long-haul truck drivers at a major truckstop in central North Carolina over a six month period. Results: Daily hours worked (mean = 11 hours, 55 minutes) and frequency of working over government-mandated daily HOS regulations (23.8% "frequently or always") were statistically significant predictors of sleep duration. Miles driven per week (mean = 2,812.61), irregular daily hours worked (63.8%), and frequency of working over the daily hour limit (23.8% "frequently or always") were statistically significant predictors of sleep quality. Conclusion: Implications of findings suggest a comprehensive review of the regulations and operational conditions for commercial motor vehicle drivers be undertaken.

• Journal of international Conference on Electrical Machines and Systems
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• v.1 no.4
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• pp.412-418
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• 2012

Eddy current brakes are electromechanical devices used as variable mechanical loads for testing electrical machines. Accurate modeling of eddy current loss is an important t factor for optimum design of eddy brake systems. In this second part, we propose novel formulations of eddy current loss in novel claw-pole eddy brake system. The proposed model for eddy current loss in novel claw-pole eddy brake system depends on the size of the claw poles. Also, in this paper, the flux density is measured by using the magnetic circuit of the novel claw pole. The model results are compared with experimental results and they are found to be in good agreement.

• Journal of Power Electronics
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• v.18 no.5
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• pp.1380-1397
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• 2018

The synchronous reluctance motor (SynRM) servo-drive system has highly nonlinear uncertainties owing to a convex construction effect. It is difficult for the linear control method to achieve good performance for the SynRM drive system. The nonlinear backstepping control system using upper bound with switching function is proposed to inhibit uncertainty action for controlling the SynRM drive system. However, this method uses a large upper bound with a switching function, which results in a large chattering. In order to reduce this chattering, a nonlinear backstepping control system using an adaptive law is proposed to estimate the lumped uncertainty. Since this method uses an adaptive law, it cannot achiever satisfactory performance. Therefore, a nonlinear backstepping control system using a reformed recurrent Hermite polynomial neural network with an adaptive law and an error estimated law is proposed to estimate the lumped uncertainty and to compensate the estimated error in order to enhance the robustness of the SynRM drive system. Further, the reformed recurrent Hermite polynomial neural network with two learning rates is derived according to an increment type Lyapunov function to speed-up the parameter convergence. Finally, some experimental results and a comparative analysis are presented to verify that the proposed control system has better control performance for controlling SynRM drive systems.

• Journal of Power Electronics
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• v.18 no.5
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• pp.1409-1423
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• 2018

Compared with classical linear controllers, a nonlinear controller can result in better control performance for the nonlinear uncertainties of continuously variable transmission (CVT) systems that are driven by a synchronous reluctance motor (SynRM). Improved control performance can be seen in the nonlinear uncertainties behavior of CVT systems by using the proposed mingled revised recurrent Hermite polynomial neural network (MRRHPNN) control with mend ant colony optimization (ACO). The MRRHPNN control with mend ACO can carry out the overlooker control system, reformed recurrent Hermite polynomial neural network (RRHPNN) control with an adaptive law, and reimbursed control with an appraised law. Additionally, in accordance with the Lyapunov stability theorem, the adaptive law in the RRHPNN and the appraised law of the reimbursed control are established. Furthermore, to help improve convergence and to obtain better learning performance, the mend ACO is utilized for adjusting the two varied learning rates of the two parameters in the RRHPNN. Finally, comparative examples are illustrated by experimental results to confirm that the proposed control system can achieve better control performance.

• The Journal of Korean Physical Therapy
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• v.23 no.2
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• pp.31-36
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• 2011

Purpose: We investigated the effects of physical practice, mental practice, and cross education using serial reaction time (SRT) in the non-dominant left arm of right-handed individuals. Methods: Subjects were divided into three groups; physical practice (n=8), mental practice (n=8) and controls (n=8). They did, respectively, physical training or mental training, or had no intervention for three weeks. Super lab 4.0 displayed four symbols on the monitor and subjects were asked to push the matching button. Reaction time was assessed pre- and post-intervention. Results: Reaction time was significantly lower after physical practice (p<0.05), but mental practice did not significantly lower reaction time? in the left hand. Also, reaction time was not significantly lower after physical practice or mental practice in the right hand. Conclusion: Physical practice can improve motor learning, but mental practice is not sufficient. Also, neither physical practice nor mental practice is sufficient for cross education from the nondominant to the dominant arm.

• Journal of Fisheries and Marine Sciences Education
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• v.7 no.1
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• pp.111-126
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• 1995

In general, the electromagnetic transient phenomenon always exists in induction motor(IM) with the torque change. The control performance of IM is very worse than that of D.C motor owing to this transient phenomenon. So many studies about the elimination methods of the transient phenomenon have been making progress. Interesting methods of them are the Field acceleration method(FAM) and the method of impulse addition on the input voltage at the time point of torque change. In this paper, first, the circuit equation of IM is derived from the phase segregation method. The torque equation consisted of the stator and rotor currents is derived from the solving of the circuit equation. As we well known, the transient terms exist in this the torque equation. The method of impulse addition on the input voltage at the instance of torque change is confirmed theoretically for the elimination of the transient phenomenon. With the base on it, the author proposed a real time algorithm to eliminate the transient terms. The control system is consisted of the PI controller with the feedforward of torque change. The author could confirm that the quick stepwise responses of torque and speed can be obtained from response simulations.

• Journal of Fisheries and Marine Sciences Education
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• v.29 no.3
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• pp.778-784
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• 2017

This paper proposes a sensorless speed control of a permanent magnet synchronous motor (PMSM) based on an adaptive sliding mode observer (SMO) for electric propulsion system of small ships. An adaptive observer gain is proposed based on the Lyapunov's stability criterion to reduce the chattering problem at any speed operation instead of the constant gain observer. Furthermore, a cascade low-pass filter with variable cut-off frequency is suggested to strengthen the filtering capability of the observer. The experimental results from a 1.5 kW PMSM drive are provided to verify the effectiveness of the proposed adaptive SMO. The result shows that the proposed method gives good speed control performances even when the PMSM operates at 0.5% from its rated speed value.

• Transactions of the KSME C: Technology and Education
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• v.2 no.2
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• pp.81-87
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• 2014

Automotive field specialist developed National Competency Standards for Automotive Maintenance to apply for the education and evaluation of automotive maintenance. National Competency Standards scope and system for Automotive Maintenance has been developed and provided Performance Criterion, knowledge, skill, attitude, and evaluation methods for each item. Also it has provided vocational basic knowledge level and qualification frame for automotive maintenance.

• Journal of the Korean Home Economics Association
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• v.44 no.2 s.216
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• pp.103-112
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• 2006

This study followed the standardization study pool of K-BSID-II to examine the stability of K-BSID-II. One hundred and ninety five infants aged from 1-42 months tested twice with intervals of 5-16 month between tests. All participants had been full-term babies without any medical complications. There were no significant differences between the groups which were divided in terms of demographic variables such as mothers' education, infants' birth order and gender. The stability of K-BSID-II was significant and that of the mental scale was lower than that of the psycho-motor scale: There were high stabilities between raw scores in two sessions(r=.91 for the mental scale and r=.89 for the psycho-motor scale) but there were significant but low correlations between mental index scores(r=.18, p<.05) and psycho-motor index scores(r=.17, p<.05). The stability was increased with initial test age and mothers' education. It was recommended for testers and researchers to use both raw scores and index scores for better interpretations in future research.