• The Journal of Korean Physical Therapy
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• v.32 no.6
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• pp.325-328
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• 2020

Purpose: This study examined the effects of the directions of neck rotation position on the muscle activity and strength of the elbow flexor and extensor muscle. Methods: Forty-one healthy adults participated in this study. The subjects were asked to their elbow 90° flexion in three different neck rotations (neutral, ipsilateral, and contralateral) in the sitting position. The muscle activities of the biceps and triceps brachii muscle were measured using surface electromyography. And the muscle strength of the elbow flexor was measured using dynamometer. One way repeated measures ANOVA was used to compare the muscle activity and strength of the elbow flexor and extensor depending on the different neck turning directions. Results: There were significant differences between contralateral neck rotation and ipsilateral neck rotation, contralateral neck rotation and neutral position. But, there was no significant difference in the triceps brachii muscle activity in comparison with the neck rotation. There were significant differences between contralateral neck rotation and ipsilateral neck rotation, contralateral neck rotation and neutral position. Conclusion: To summarize this study, the elbow flexor and extensor muscle activity and strength was highest in the contralateral neck rotation position. In other words, it was possible to confirm the effect of Asymmetrical Tonic Neck Reflex in healthy adults whose primitive reflexes were inhibition, and head and neck positions should be considered during clinical evaluation and treatment.

• Journal of Korean Foot and Ankle Society
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• v.14 no.1
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• pp.21-24
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• 2010

Purpose: The incomplete reduction of the sesamoid has lately been issued as cause for recurrence. In this study, we analysed factors that may influence reduction of sesamoid. Materials and Methods: The study consists of 50 cases operated by single surgeon. Eighteen cases were done by proximal chevron osteotomy, and 32 cases were done by scarf osteotomy. Hallux valgus (HV) angle and intermetatarsal (IM) angle were measured before and three months after the surgery. Sesamoid position (SP) was classified according to Hardy and Clapham grade system. Results: After the proximal chevron osteotomy, the correction of the mean HV angle was $19.5^{\circ}$, and IM angle was $6.2^{\circ}$. SP was changed from 5.6 to 3.4 grade. After the Scarf osteotomy, the correction of the mean HV angle was 25 degree, and IM angle was $9^{\circ}$. SP was changed from 5.5 to 2.8 grade. There was difference of sesamoid's correction between two different method of surgery (p=0.127). However, better correction of sesamoid was witnessed with bigger correction angle regardless of method of surgery (p=0.002, 0.001). Conclusion: We believe surgical method do not effect sesamoid's correction but more correction angle can result in better correction of sesamoid position.

• The Journal of Korean Physical Therapy
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• v.31 no.6
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• pp.333-338
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• 2019

Purpose: Although previous studies on the screw-home movement (SHM) for autopsy specimen and walking of living persons conducted, the possibility of acquiring SHM based on inertial measurement units received little attention. This study aimed to investigate the possibility of measuring SHM for the non-weighted bearing using a micro-electro-mechanical system-based wearable motion capture system (MEMSS). Methods: MEMSS and camera-based motion analysis systems were used to obtain kinematic data of the knee joint. The knee joint moved from the flexion position to a fully extended position and then back to the start point. The coefficient of multiple correlation and the difference in the range of motion were used to assess the waveform similarity in the movement measured by two measurement systems. Results: The waveform similarity in the sagittal plane was excellent and the in the transverse plane was good. Significant differences were found in the sagittal plane between the two systems (p<0.05). However, there was no significant difference in the transverse plane between the two systems (p>0.05). Conclusion: The SHM during the passive motion without muscle contraction in the non-weighted bearing appeared in the entire range. We thought that the MEMSS could be easily applied to the acquisition of biomechanical data on the knee related to physical therapy.

• Journal of the Korean Society for Precision Engineering
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• v.33 no.10
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• pp.857-864
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• 2016

In this study, we proposed a novel concept of electric sun visor comprising a dark, see-through sun shade material that ensures unimpaired driver's vision with continuous control of the shade position. The shade extending from the windshield base along its surface may be subjected to severe vibration during driving unless the design parameters are carefully selected. A prototype was tested to collect acceleration data during driving. Based on the test data, an ADAMS dynamics model was validated. The mechanism of sun visor was optimized to minimize vibration based on the dynamics model, experimental design, and response surface method.

• Journal of the Korean Solar Energy Society
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• v.22 no.4
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• pp.10-17
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• 2002

This study aims to develop the analysis tool that assesses the sunlight at any given point of a window or solar collector array shaded by surrounding obstacles. The development of this software, named SunChart, focused to the user-friendliness and the reliability. This SunChart can calculate the solar radiation as well as shading on the certain face. The calculation results by SunChart show by both numerically and graphically and are in a good agreement with ones obtained from "Sunrise Sunset" developed at Korea Astronomy Observatory and from TRNSYS.

• Journal of Power Electronics
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• v.13 no.6
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• pp.1051-1057
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• 2013

This paper proposes an implementable sun tracking algorithm for portable systems powered by alternative energy sources. The proposed system uses a 2-axis tilt sensor and a 3-axis magnetic sensor to measure the orientation and posture of the system, according to a horizon coordinates system, and compensate for tilt effects. Then, through an astronomical calculation, using the present time and position information obtained from GPS sensors, the azimuth and altitude of the sun in that location is calculated and converted to portable sun tracking system coordinates and used to control the A- and C-axes of the system.

• Journal of the Korean Society of Industry Convergence
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• v.13 no.2
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• pp.69-75
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• 2010

This paper describes the design and implementation of hybrid sun tracking solar power generation system designed by combining astronomical data with optical tracking mechanism. The advantages of proposed power generation system are small amounts of calculation for tracking operations and enhancement of 40% of power generation at best. This system is able to track toward optimal position for maximum sun-lights under scattered lights due to clouds. The performance of implemented power generation system is confirmed by field experiments.

• Proceedings of the KIEE Conference
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• 1998.11b
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• pp.429-431
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• 1998

In this paper, the sun-seeker control system that is driven by DC motor is modeled on linear 2nd order time invariant system under some assumptions. For the analysis of output characteristics, theory is developed using digital control methods. Computer simulation and numerical analysis has been performed.

• Journal of Power Electronics
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• v.6 no.4
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• pp.347-355
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• 2006

A new control method for precision robust position control of a permanent magnet synchronous motor (PMSM) is presented. In direct drive motor systems, a load torque disturbance directly affects the motor shaft. The application of the load torque observer is published in using a fixed gain to solve this problem. However, the motor flux linkage cannot be determined precisely for a load torque observer. Therefore, an asymptotically stable adaptive observer base on a deadbeat observer is considered to overcome the problems of unknown parameters, torque disturbance and a small chattering effect. To find the critical parameters the system stability analysis is carried out using the Liapunov stability theorem.

• Proceedings of the KSR Conference
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• 2011.10a
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• pp.1092-1099
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• 2011

This paper is concerned with the ATO speed profile generation method in the moving block system. The ATO speed profile is calculated using the acceleration limit and the jerk limit to improve ride comfort. In addition, the speed limit and stop distance provided from ATP profile should be considered to ensure safety. In the moving block system, the speed limit and the stop position are frequently changed in real-time. Therefore, the ATO speed profile should be regenerated immediately according to change of the speed limit and the stop position, within the acceleration limit and the jerk limit. In this paper, the ATO speed profile generation method is proposed, which considers not only frequent changes of the speed limit and the stop position but also acceleration limit and jerk limit. Futhermore the simulation result is presented to verify usefulness of this method.