• Korean Journal of Childcare and Education
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• v.11 no.5
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• pp.135-151
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• 2015

The purpose of this study was to investigate the relationship between preschoolers' motor proficiency and their executive function. Participants were 72 children who participated in individual tests. Motor proficiency was measured by a shortened form of the Bruininks-Oseretsky Test of Motor Proficiency Second Edition(BOT-2). Executive functions were assessed by utilizing the revised version of the four tasks: 'Day-Night Task', 'Dimensional Change Card Sort Task', 'Lift Flag Task' and 'Digit Span Task'. The major findings were as follows. First, the 5-year-olds motor proficiency was found to be better than the 4-year-olds. Second, the 5-year-olds executive function was found to be better than the 4-yeat-olds. Last, the 4-year-olds' and 5-year-olds' motor proficiency was related to their executive function. Concretely, fine manual control of motor proficiency was executive function and there was a high correlation. And behavior response inhibition and working memory of executive function was motor proficiency and there was a high correlation. Data analysis showed that preschoolers' motor proficiency and their executive function were different by their age level and that preschoolers' motor proficiency was correlated with their executive function.

• Journal of Institute of Control, Robotics and Systems
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• v.20 no.7
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• pp.706-712
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• 2014

The inverters used to drive Brushless DC motors (BLDC) include switching devices such as FETs and the faults in FETs cause severe performance degradation in systems where a BLDC acts as actuator. This paper presents a fault detection and isolation method for the FETs of an inverter for BLDC motor control systems, which is based on the EKF (Extended Kalman filter). Firstly, an equivalent circuit model for a BLDC motor plus its inverter system was derived. Secondly, a state-space equation was established, where the on-resistance of the FETs is expressed as a state variable and the EKF equation estimates the on-resistance. If the estimated resistance differs greatly from the known value, it can be asserted that there is a fault on that FET. Thirdly, the local convergence of the established EKF was proved. Finally, through the experiments, the performance of the proposed method was verified. The results show that the on-resistance is estimated close to the value specified in the FET data sheet in normal operation, whereas the estimated resistance is a much larger value than the normal one in case an FET fault occurs. Therefore, it is confirmed that the proposed fault detection and isolation method works appropriately in real systems.

• Journal of the Korean Academy of Child and Adolescent Psychiatry
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• v.1 no.1
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• pp.161-171
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• 1990

The study was to examine the effectiveness of the educational program for the parents of autistic children in promoting the development and amelioration of psychopathology. Behavioral pathology and developmental function of autistic children of two parent groups, parents who participated in educational program and parents who did not participate in that program, were compared before and after partent education program. For these purpose, the data were collected from 30 subjects(15 for participant group and 15 for non-participant group) who were diagnosed as Autism according to DSM-III at Child-Psychiatry of Seoul National University Hospital during May 16, 1987 through April 30, 1988. Pre and post tests by Schopler's Psycho-Educational Profile scale were performed for all of the subjects and the data were analyzed by Wilcoxon Rank Sum test, Wilcoxon Sign Rank test and $X^2-test.$ The results obtained were as follows ; 1) The autistic children of participant group were significantly higher than those of non-participant group after education on Imitation, Gross motor and Eye-hand Integration scale of developmental function area (p<0.05) 2) After education, the autistic children of participant group were significantly improved in Affect and Language scale of behavioral pathology area (p<0.05). 3) After education, the autistic children of participant group were significantly improved in developmental function, such as perception, Fine motor, Gross motor, Eye-hand Integration, Cognitive Performance, Cognitive Language (p<0.05). 4) The autistic children of non-participant group were significantly improved in Relating behavior and developmental functions such as Perception, Fine motor and Eye-hand Integration at post test in comparison to pre test (p<0.05). From these results, it might be concluded that the autistic children of participant group were improved much more, and obtained higher score in developmental function area than those of non-participant group. It is suggested that this kind of education program helped and supported the parents to do some more appropriate approach for the development of their children.

• Journal of Electrical Engineering and Technology
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• v.12 no.2
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• pp.665-673
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• 2017

This paper proposes a field weakening control method for operating an induction motor with a variable DC input voltage condition. In the variable DC voltage condition such as a battery, the field weakening method are required for the maximum output power. The conventional field weakening control methods can be used for operating the induction motor over the rated speed in a constant DC-link voltage condition. However, the conventional methods for operating the motor with the variable DC voltage is not suitable for the maximum output power. To overcome this problem, this paper proposes the optimized field weakening control method to extend the operating range of the induction motor with a rated power in a limited thermal and a wide DC input voltage conditions. The optimized d-axis and q-axis current equations are derived according to the field weakening region I and II to extend the operating region. The experimental results are presented to verify the effectiveness of the proposed method.

• Journal of Power Electronics
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• v.10 no.6
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• pp.647-659
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• 2010

This paper presents a part of North Africa/Europe collaboration results in education to develop project-oriented courses in power electronics and motor drive field. The course aims to teach Permanent Magnet motor drives close to a real world project of significant size and depth so as to be motivational, namely mobile robot project. Particular skills, student will acquire, are those relative to the detailed design and implementation of PM motor controllers in DSP based rapid prototyping environment. Simulation work is completed using graphical modeling tools in Simulink/Plecs, while real-time implementation is achieved by means of eZdspF2812 board and Simulink/TI C2000 Embedded Target tools. This flexible development environment fit the robot traction system very well and provides exactly the functionality necessary for an efficient PM motor drives teaching as demonstrated by a set of simulation and experiments.

• Journal of international Conference on Electrical Machines and Systems
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• v.3 no.4
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• pp.374-378
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• 2014

PID control method usually has problems of overshoot and oscillation in high order control system, therefore, it is important to improve the control method so as to reduce the overshoot and oscillation. Based on MATLAB simulation, a permanent magnet (PM) DC servomotor control system is studied in this paper. The motor is modeled according to the universal motor theory, and with the help of the fourth order Ronge-Kutta method, its speed control is simulated and compared between two different dual closed-loops PWM control methods. This case study helps undergraduate students to better understand theories related to electrical engineering, such as electrical machinery, power electronics and control theory, as well as digital solution of state equations.

• Transactions of the Korean Society of Automotive Engineers
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• v.22 no.6
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• pp.75-82
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• 2014

The purpose of this study is to identify the effects of sensation seeking and driving confidence level on reckless driving behavior in motor sports club's members. Data was collected from 265participants of the Trackday, driving school. Subjects answered the questionnaire using convenient sampling method. Data which is obtained through self-administration was analyzed by using the frequency analysis and multiple regression. Results are as follows. First sensation seeking has influenced on reckless driving behavior such as, drunken driving and errors. Second, driving confidence level has influenced on reckless driving behavior such as, drunken driving, overspeed driving and errors.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2006.10a
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• pp.259-260
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• 2006

• Journal of the Korean Applied Science and Technology
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• v.36 no.4
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• pp.1041-1049
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• 2019

This study gathered previous studies on the effects of image training in school physical education conducted in korea in order to investigate the average effect size as well as the factors that influence the effect sizes. This study connoted findings of individual studies related to image training in school physical education from 1995 to 2018. The results of this study were as follows: Firstly, the overall mean effect size of the image training in school physical education was large size(Cohen, 1988). Secondly, motor skills showed the large effect size than psychological variable. Thirdly, major factors that influence the effect of image training in school physical education appeared to be the type of motor learning, age, gender, training period, training frequency, training ime. Based on these findings, implications for future research and application of image training in school physical education were suggested.

• 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.