• Journal of Electrical Engineering and Technology
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• v.13 no.5
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• pp.2125-2133
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• 2018

To achieve high performance speed regulation, a robust adaptive speed controller is proposed for the permanent magnet synchronous motor (PMSM) subject to parameter uncertainties and input saturations in this paper. A nonlinear adaptive control is introduced to compensate the PMSM speed tracking errors due to uncertainties, disturbances and control input saturation constraints. By combining the adaptive control and the nonlinear robust control based on the interconnection and damping assignment (IDA) strategy, a new robust adaptive control is designed for speed regulation of PMSM. Stability and robustness of the closed-loop control system involved with the constrained control inputs rather than unconstrained control inputs are validated. Simulations for PMSM control in the presence of uncertainties and saturations nonlinearities show that the proposed approach is effective to regulate speed, and the average tracking error using the proposed approach is at least 32% smaller than the compared methods.

• Korean Journal of Applied Biomechanics
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• v.12 no.1
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• pp.221-231
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• 2002

The purpose of this study was to clarify the differences in service patterns of a forward and backward soft tennis players using 3D motion analyzer. Subjects were 4 forward players of $24.0\pm5.23$yrs and 4 backward players of $23.5\pm1.73$yrs. The results were as following: 1. There was no difference among each positions on swinging-time. The longest racket swinging-time was in the phase of takeback, the second one was in follow-through. The shortest one was in the phase of forward-swing so called force production phase, which had an influence on ball's velocity. 2. The racket speed on impact was 16.3m/s in forward subject and 19.53m/s in backward subject, when each velocity of balls was 44.6m/s, 52.9m/s. Although there was no significant difference along by positions, backward subject showed faster result. 3. The maximum speed of each performance was reached before the impact, and the speed at impact along by positions did not show any significant difference. The summation of velocity was measured in good order as following; hip, shoulder, elbow, wrist, top of racket. 4. In the angular velocity of all examine except one, the angular velocity of forearm was bigger than the one of racket top although there was no statistically significant difference between forward and backward subject. 5. The service grip of the forward players was shorter than that of backward players.

• Proceedings of the KSR Conference
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• 2005.05a
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• pp.211-219
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• 2005

The railway industry of each country has variant technical standards and regulations unlike other industries. For this reason, it is necessary to investigate the domestic technical standards and regulations and to prepare the countermeasure of the variance for advancing the korean high-speed railroad system into foreign market. This study was designed to investigate the railway design/manufacturing, examination/inspection and safety of domestic and foreign countries subject to a world market for advancing the korean high-speed railroad system into a foreign market. Because the reliance of a railroad system is a prerequisite for the safety of railroads, it is very important to obtain the reliance data, which is based on the RMS analysis of foreign countries subject to a world market.

• Advances in concrete construction
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• v.7 no.1
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• pp.23-30
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• 2019

Five key items were used to create an economical and physically small impact test device for concrete panels subject to high speed collision: an air-compressive system, carbon steel pipe, solenoid valve, carrier and carrier-blocking, and velocity measurement device. The impact test device developed can launch a 20 mm steel spherical projectile at over 200 m/s with measured impact and/or residual velocity. Purpose for development was to conduct preliminary materials tests, prior to large-scale collision experiments. In this paper, the design process of the small impact test device was discussed in detail.

• Korean Journal of Applied Biomechanics
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• v.17 no.4
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• pp.1-8
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• 2007

The purpose of this study was to investigate the difference in the stride-to-stride variability between two treadmill conditions; traditional treadmill and special treadmill whose speed can be adjusted automatically by subject's walking speed. Eight male subjects (25.1 years, 172.7 cm, 66.6 kg) were participated in treadmill walking experiment. First, preferred walking speed (PWS) of each subject was determined. Second, each subject performed walking experiment with fixed PWS condition and with free PWS condition for 10 minutes. 3D motion capture system (Motion analysis Corp., USA) with 6 cameras was used to collect motion data with sampling frequency of 120Hz. Temporal and spatial variables for stride-to-stride variability were calculated. Coefficient of variance (CV) which quantifies the amount of variability and Detrended Fluctuation Analysis (DFA) which explains the structure (self-similarity) of the variability were used for analysis. Results showed that the amount of variability during free PWS condition was greater than that of fixed PWS condition. DFA results showed that there was a statistical difference between two treadmill conditions for the variables of step length, stance time, and double support time. From these results, it is possible that traditional treadmill study might give incorrect conclusion about gait variability study. Further study is necessary to clarify these matters by considering the number of subjects, experimental time, and gait variables for the study of stride-to-stride variability.

• Proceedings of the KIEE Conference
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• 2003.04a
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• pp.331-334
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• 2003

In this paper, on the subject of a speed control wind turbine, the type of wind speed reference decision between conventional MPPT tracking speed control and MPPT with LPF(Low Pass Filter) speed control algorithm are introduced and its performances are compared using a model based on MATLAB Simulink, and to get more realistic output data, the stored wind data as its wind speed input from 30kW wind power system in Buan, Haechang is used.

• Journal of the Ergonomics Society of Korea
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• v.21 no.3
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• pp.25-34
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• 2002

The road sign in dynamic traffic system is an important element which affects on human cognitive performance on driving. Web-based vision system simulator was developed to examine the cognition time of the road sign in dynamic environment. This experiment the cognition time of the road sign in dynamic environment. This experiment was designed in with-subject design with two factors: vehicle speed and the amount of information of the traffic sign. It measured the cognition time of the road sign through two evaluation methods: the subjective test with vision system simulator and computational cognitive model. In these two evaluations of human cognitive performance under the dynamic traffic environment, it demonstrated that subject's cognition time was affected by both the amount of information of traffic sign and driving speed.

• Proceedings of the Korea Society for Simulation Conference
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• 2002.05a
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• pp.163-168
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• 2002

The road sign in dynamic traffic system is an important element which affects on human cognitive performance on driving. Web-based vision system simulator was developed to examine the cognition time of the road sign in dynamic environment. This experiment was designed in within-subject design with two factors; vehicle speed and the amount of information of the traffic sign. It measured the cognition time of the road sign through two evaluation methods; the subjective test with vision system simulator and computational cognitive model. In these two evaluations of human cognitive performance under the dynamic traffic environment, it demonstrated that subject's cognition time was affected by both the amount of information of traffic sign and driving speed.

• Bulletin of the Society of Naval Architects of Korea
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• v.21 no.4
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• pp.21-28
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• 1984

As a way of overcoming or improving the great depression in he world shipping and shipbuilding industries, a great effort has been made on the development of fuel-economic hull forms. Recently, the author(s) had presented part of the results of his study on this subject(full slow speed ships) in PRADS 83, and are presently carrying out the research program on the same subject for fine fast speed ships. This paper is the introduction and summary of the basic concept and mathematical treatment applied in this research.

• Journal of Institute of Control, Robotics and Systems
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• v.17 no.5
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• pp.505-511
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• 2011

In this paper, we have developed an automatic velocity control system of a small-sized commercial treadmill (belt length of 1.2 m and width of 0.5 m) which is widely used at home and health centers. The control objective is to automatically adjust the treadmill velocity so that the subject's position is maintained within the track when the subject walks at a variable velocity. The subject's position with respect to a reference point is measured by a low-cost sonar sensor located on the back of the subject. Based on an encoder sensor measurement at the treadmill motor, a state feedback control algorithm with Kalman filter was implemented to determine the velocity of the treadmill. In order to reduce the unnatural inertia force felt by the subject, a predefined acceleration limit was applied, which generated smooth velocity trajectories. The experimental results demonstrate the effectiveness of the proposed method in providing successful velocity changes in response to variable velocity walking without causing significant inertia force to the subject. In the pilot study with three subjects, users could change their walking velocity easily and naturally with small deviations during slow, medium, and fast walking. The proposed automatic velocity control algorithm can potentially be applied to any locomotion interface in an economical way without having to use sophisticated and expensive sensors and larger treadmills.