• Journal of Drive and Control
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• v.13 no.3
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• pp.32-38
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• 2016

For this paper, the position-control performances of dual EHA(electro-hydrostatic actuator) systems were investigated according to two cases wherein the double-rod- and single-rod-type hydraulic cylinders were combined. Since the control performance is significantly dependent on the load conditions including external forces such as the inertia load, it is proposed here that the two sub-EHAs are driven by separate position and force controllers, instead of two identical position controllers. According to the simulation results, the best performance was achieved by the position-controlled single-rod-type EHA that was combined with a force-controlled double-rod-type EHA. As the force-controlled double-rod-type EHA compensated for the external loads on the position-controlled single-rod-type EHA, the position-control performance was not influenced by external forces including the inertia load. In addition, the position-controlled single-rod-type EHA contributed to the enhancement of the damping ratio by absorbing the pressure peaks through its internal accumulator. Due to the symmetrical piston areas, the double-rod-type EHA is more suitable for force control than the single-rod- type EHA.

• Journal of the Korean Solar Energy Society
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• v.21 no.4
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• pp.55-62
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• 2001

A parabolic dish concentrator used in a high temperature application of solar energy tracks the sun's movement by two axis sun tracking system. In such a system, sun tracking performance affects the system efficiency directly. Generally the higher the tracking accuracy is, the better the system performance is. A large number of parabolic dish type concentrators has been developed and implemented in the world. However none of them clearly provided a qualitative method of how the accuracy of the sun tracking system can be evaluated. The work presented here is the evaluation of sun tracking performance of parabolic dish concentrator, which follows the sun's movement by the sensor, using a computer vision system. We install a camera on the parabolic dish concentrator. While the concentrator follows the sun, sun's images are captured continuously. Then the performance of sun tracking system was evaluated by analyzing the variation of the position of the sun in the captured images.

• Journal of Korean Clinical Nursing Research
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• v.16 no.1
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• pp.5-15
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• 2010

Purpose: The purpose of this study was to examine the effect of position change on the level of comfort and occurrence of bleeding after transarterial chemoembolization. Methods: This study was the nonequivalent control group non-synchronized design. The experimental group was positioned in supine with 15-30 degree Semi-folwer's position for 2 hours and then changed supine position alternatively to 30 degree lateral positioning in turn per hour for 2 hours. For the control group, 6 hour supine positions without any position change were applied. Results: The level of discomfort of the control group was scored higher level than that of the experimental group. There was no significant differences in back pain and the degrees of voiding difficulty. There were no significant differences in the incidence of bleeding complication between the two groups. Conclusion: The position change in patients after transarterial chemoembolization could be applied without any severe side effects such as bleeding complication, but it was revealed to be effective in reducing the level of discomfort.

• Journal of Korean Academy of Nursing
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• v.33 no.4
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• pp.488-494
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• 2003

Purpose. To examine the effects of body position and time after feeding on gastric residuals in low birth weight infants(LBW). Methods. A repeated measures design was conducted. Twenty LBW infants being fed via indwelling nasogastric tubes were randomly assigned to one of 5 different position orderings. In each position, gastric residuals were measured at 30, 60, 90, 120, 150, and 180 minutes after feeding. Results. In comparisons of gastric residuals with position and time, the main effects of position and time were statistically significant (F=5.038, p=0.001; F=429.763, p < 0.001, respectively), but the interaction between position and time was found not to be significant. In pairwise comparisons, the gastric residuals were more reduced in the right anterior oblique and prone positions compared with the left lateral position (p < 0.05) and the differences across time periods were significant (p < 0.001). Conclusions. The body position after feeding has a significant affect on gastric residuals over time in LBW infants. The right anterior oblique or prone position is recommended rather than left lateral position after feeding. Knowledge of the proper position and the pattern of gastric emptying over time after feeding may lead to the development of evidence-based nursing care.

• Journal of the Korean earth science society
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• v.32 no.5
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• pp.514-520
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• 2011

As homework, a total of 32 seventh grade science-gifted students were asked to observe the moon at daily intervals for one month duration. They were also asked to take the photos and to record relevant variables in a given format. The purpose of the task was to investigate what students thought, as they observed the moon. The results show that students paid attention mainly to the position of the moon relative to other variables such as the date in the lunar calendar, the observer's position on the earth, and the position of the sun. Overall students' response implied that students did not observe the lunar phase in relation with relevant variables. Some reponses from students show common misconceptions such as the cause of the lunar phase to reflect the shadow of the earth. However, some responses reveal students' idea that has been rarely reported in the previous researches. For example, some students drew the moon to revolve in the opposite direction. Significant number of students drew the sun's position to be due west before the full moon and due east after the full moon. Few students recognized the relation between the time of observation and observer's position on the earth. The results of current research suggest that not only the education but also the research needs to be expanded to consider informal environment such as the actual field conditions.

• Korean Journal of Oriental Medicine
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• v.17 no.2
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• pp.85-100
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• 2011

Objectives : This study aimed to investigate the effect of four common types of Qigong position (standing, sitting, supine, and horse-riding position) on the autonomic nervous system. Method : Thirty healthy subjects participated in this study once a week for four weeks. Heart Rate Variability (HRV) was measured three times (before, during, and after the position) while the subject maintained one of four positions for ten minutes. Result : There were significant changes HRV in the standing position. In the sitting position, both the sympathetic and parasympathetic nerves were activated. On the other hand, in the spine position, heart rate (HR) was decreased. Activation of sympathetic and parasympathetic nerves was also observed in this position. Significant increases of indices related to awakening and concentration were observed accompanied by increase of HR and a sympathetic nerve was activated in the riding-horse position. Conclusions : In the present study, it was shown that each Qigong position caused various and significant changes in autonomic nervous system. It would be expected that these results can be applied to choose appropriate Qigong position according to objective of Qigong therapy although it is remained to further evaluate the effects of long-term maintenance of Qigong positions and repeated Qigong training.

• Journal of the Korean Society of Physical Medicine
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• v.4 no.4
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• pp.221-229
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• 2009

Purpose : The purpose of this study was to assess the effect of bridging stabilization exercises of trunk muscles activity on a Swiss ball according to change of position. Methods：30 healthy university students volunteered to participate in this study. Subjects were required to complete following three exercise positions. Exercise position 1; Supine bridge with Swiss ball, Exercise position 2; Side bridge with Swiss ball, Exercise position 3; Prone bridge with Swiss ball. Surface electromyography from selected trunk muscles was normalized to maximum voluntary isometric contraction. Results : A repeated measures of ANOVA with Duncan's correction was used to determine the influence of exercise type on muscle activity for rectus abdominis, external oblique, erector spinae. The erector spinae of exercise position 1 showed significantly higher muscle activity than exercise position 2, 3(p<.05). The external oblique of exercise position 2, 3 showed significantly higher muscle activity than exercise position 1(p<.05). The rectus abdominis of exercise position 3 showed significantly higher muscle activity than exercise position 1, 2(p<.05) Conclusion： These results indicate that muscle activity can be influenced by addition of a Swiss ball in bridging exercises. It is recommend to use a Swiss ball for trunk stabilization exercise.

• Proceedings of the KIEE Conference
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• 2006.10c
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• pp.330-332
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• 2006

In this paper, sun tracking system using Sun position sensor is proposed, the sun tracking system designed as which raises the efficiency of solar power generation. It design the structure being simple and it develops the system which is economical efficiency. It develops the hazard technique such as location tracking method of the sun which uses the sensor and to use the motor solar cell module movement. The Sun tracking system makes the drive in order to do with one axis and to use the sensor and to know in order to put out, the location of the sun and it makes. To make the solar location tracking sensor where the structure is simple it used two solar cells.

• Journal of the Institute of Electronics Engineers of Korea SC
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• v.39 no.6
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• pp.59-70
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• 2002

This paper proposes a position and speed sensorless vector control for Synchronous Reluctance Motor(SynRM) operating at optimum efficiency and high response, in which core loss is taken into account, and discusses the performance of system. The proposed control scheme is based on the flux estimation combined stator voltage and current. In this paper, current angle condition of efficiency optimization which minimizes the copper and iron losses is derived based on the equivalent circuit model of the SynRM. The research result of closed loop position and speed control with efficiency optimization control is given to verify the proposed scheme.

• Journal of Institute of Control, Robotics and Systems
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• v.14 no.10
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• pp.969-976
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• 2008

A position control problem is studied for UEV(Unmanned Expedition Vehicles), which is to follow pre-determined paths via fixed way-points. Hybrid control systems are used for position control of UEV depending on the operating condition. Speed control consists of three controllers: PID control, adaptive PI control, and neural network. Heading control consists of two controllers, PID and adaptive PID control. The controllers are selected based on the changes of road conditions. We suggest an adaptive PI control algorithm for speed control and an transition management algorithm among the controllers. The algorithm adapts the road conditions and variation of vehicle dynamical characteristics and selects a suitable controller.