• Journal of the Korean Society of Physical Medicine
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• v.3 no.2
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• pp.63-74
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• 2008

Purpose : The purpose of this study was to compare trunk repositioning errors between subjects with and without low back pain in sitting and standing. Methods : Total 81 participants were recruited who consisted of 41 subjects with low back pain and 40 normal subjects. The subjects were instructed to replicate the predetermined target positions of the trunk toward upright and $30^{\circ}$ flexion in sitting and standing. During each of movement, digital inclinometer was used to measure the angular movement of $T_{12}$ spinal process. Repositioning error was calculated as the absolute difference between the predetermined target positions and replicated target positions. Results : In subjects with low back pain, upright repositioning error was $1.26^{\circ}{\pm}0.14^{\circ}$ in sitting and $1.55^{\circ}{\pm}0.24^{\circ}$ in standing, and $30^{\circ}$ flexion repositioning error was $3.23^{\circ}{\pm}0.33^{\circ}$ in sitting and $5.50^{\circ}{\pm}0.50^{\circ}$ in standing. In subjects without low back pain, upright repositioning error was $1.38^{\circ}{\pm}0.15^{\circ}$ in sitting and $1.67^{\circ}{\pm}0.18^{\circ}$ in standing, and flexion repositioning error was $2.61^{\circ}{\pm}0.28^{\circ}$ in sitting and $3.70^{\circ}{\pm}0.52^{\circ}$ in standing. It was demonstrated that flexion repositioning error increased significantly in standing position. In subjects with low back pain, $30^{\circ}$ flexion repositioning error was significantly higher in standing than in sitting. Conclusion : The repositioning error of subjects with low back pain increased during flexion and it implies that some aspects of proprioception are decreased in subjects with low back pain. Therefore, it will be emphasis that a clinical trial to increase the trunk flexion stability of subjects with low back pain in standing.

• Journal of the Korean Society of Marine Environment & Safety
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• v.29 no.2
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• pp.139-146
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• 2023

Maritime object detection systems, which detects small maritime obstacles such as fish farm buoys and visualizes distance and direction, is equipped with a 3-axis gimbal to compensate for errors caused by hull motion, but there is a limit to distance error corrections necessitated by the vertical movement of the camera and the maritime object due to wave motions. Therefore, in this study, the distance error of maritime object detection systems caused by the movement of the water surface according to the external environment is analyzed and corrected using average filter and moving average filter. Random numbers following a Gaussian standard normal distribution were added to or subtracted from the image coordinates to reproduce the rise or fall of the buoy under irregular waves. The distance calculated according to the change of image coordinates, the predicted distance through the average filter and the moving average filter, and the actual distance measured by laser distance meter were compared. In phases 1 and 2, the error rate increased to a maximum of 98.5% due to the changes of image coordinates due to irregular waves, but the error rate decreased to 16.3% with the moving average filter. This error correction capability was better than with the average filter, but there was a limit due to failure to respond to the distance change. Therefore, it is considered that use of the moving average filter to correct the distance error of the maritime object detection system will enhance responses to the real-time distance change and greatly improve the error rate.

• Journal of Advanced Navigation Technology
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• v.19 no.1
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• pp.74-79
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• 2015

In this paper, in order to improve the error is utilized to location tracking the smart sensor detects a walking information user, RSSI is to provide an indoor position tracking system that is capable of correcting an error in terms weak. The acceleration sensor is able to detect the activity in the user walking and detects the number of step and the moving distance using the same. The Direction sensor is utilized as a digital compass, to detect the moving direction of the user. As a result of detecting the walking information using the sensor, it can be showed that this proposed indoor positioning system has a high degree of accuracy for the number of steps and the movement direction. Therefore, this paper shows that the proposed technique can correct the error of the location information to be problem in the conventional indoor location system which uses the only Wi-Fi APs by estimating the user's movement direction and distance using the sensors in smartphone without an additional equipment and cost.

• Journal of the Ergonomics Society of Korea
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• v.7 no.2
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• pp.31-44
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• 1988

If an error occurs in the automatic mode when the advanced teleoperator system performs a task in hostile environment then the automatic mode changes into the manual mode. The operation by the control program and the operation by a human recover the error in the manual mode. The system resumes the automatic mode and continues the given task. It is necessary to improve the manual mode in order to make the best use of a man-robot system, as a part of the human interface technique. Therefore, the error recovery task is performed by combining the operation by the control program representing autonomy of a robot and the operation by a human representing versatility of a human operator effectively in the view point of human factors engineering. The geometric inverse kinematics is used for the calculation of the robot joint values in the operation by the control program. The singularity operation error and the parameter operation error often occur in this procedure. These two operation errors increase the movement time of the robot and the coordinate reading time, during the error recovery task. A singularity algorithm, parameter algorithm and fuzzy control are studied so as to remove the disadvantages of geometric inverse kinematics. And the geometric straight line motion is studied so as to improve the disadvantages of the operation by a human.

• PNF and Movement
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• v.17 no.3
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• pp.463-469
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• 2019

Purpose: This study investigated the effect of plantar-flexor muscle fatigue on the force sense and joint reposition sense of ankle joints in the healthy adults. Methods: Fifteen healthy subjects (male: 9, female: 6) participated in this study. A digital dynamometer was used to measure the force sense error while a wireless motion capture device was used to measure the joint reposition sense error. To induce plantar-flexor muscle fatigue for a dominant lower extremity, the subjects were asked to perform plantar flexion until exhaustion while barefoot. The differences in force sense error and joint reposition sense error for the ankle joint were measured immediately. The Wilcoxon test was used to compare these values before and after inducing plantar-flexor muscle fatigue. Results: The force sense error and joint reposition sense error of ankle joints after inducing plantar-flexor muscle fatigue increased significantly compared to the values before inducing muscle fatigue. Conclusion: This study suggests that plantar-flexor muscle fatigue could degrade the force sense and joint reposition sense in ankle joints. In addition, it could deteriorate ankle proprioception.

• Physical Therapy Korea
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• v.27 no.3
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• pp.178-184
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• 2020

Background: Stroke patients have reduced trunk control compared to normal people. The ability to control the trunk of a stroke patient is important for gait and balance. However, there is still a lack of research methods for the characteristics of stroke control in stroke patients. Objects: The aim of this research was to determine whether trunk position sense has any relation with balance and gait. Methods: This study assessed trunk performance by measuring position sense. Trunk position sense was assessed using the David back concept to determine trunk repositioning error in 20 stroke patients and 20 healthy subjects. Four trunk movements (flexion, extension, lateral flexion, rotation) were tested for repositioning error and the measurement was carried out 6 times per move; these parameters were used to compare the mean values obtained. Subjects with stroke were also evaluated with clinical measures of balance and gait. Results: There were significant differences in trunk repositioning error between the stroke group and the control group in flexion, lateral flexion to the affected side, lateral flexion to the unaffected side, rotation to the affected side, and rotation to the unaffected side. Mean flexion error: post-stroke: 7.95 ± 6.76 degrees, control: 3.32 ± 2.27; mean lateral flexion error to the affected side: 6.13 ± 3.79, to the unaffected side: 5.32 ± 3.15, control: 3.57 ± 1.92; mean rotation error to the affected side: 8.25 ± 3.09, to the unaffected side: 9.24 ± 3.94, control: 5.41 ± 1.82. There was an only significant negative correlation between the repositioning error of lateral flexion and the Berg balance scale score to the affected side (-0.483) and to the unaffected side (-0.497). A strong correlation between balance and gait was found. Conclusion: The results of this study indicate that stroke patients exhibit greater trunk repositioning error than age-matched controls on all planes of movement except for extension. And lateral flexion has correlation with balance and gait.

• Korean Journal of Applied Biomechanics
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• v.33 no.4
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• pp.147-154
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• 2023

Objective: This study aimed 1) to compare the Landing Error Scoring System (LESS) score and movement patterns during landing of the lesser dorsiflexion range of motion (LDFROM) group to that with the greater dorsiflexion range of motion group, and 2) to identify the correlation between the weight-bearing dorsiflexion range of motion (WBDF ROM), LESS score, and movement patterns during landing. Method: Fifty health adults participated in this study. WBDF ROM was measured using the weight bearing lunge test while movement patterns during landing was assessed using the LESS. The joint angles of the ankle, knee and hip joints during landing were analyzed using the 2D video analysis. After mean value of WBDF ROM was calculated, participants were divided into two groups (GDFROM and LDFROM) based on the mean value. The Mann-Whiteny 𝒰 test was used to identify differences in movement strategies during landing between two groups and the Pearson's correlation analysis was performed to determine relationships between WBDF ROM and movement strategies. Results: The LDFROM group showed the poorer LESS score and stiffer landing kinematics during landing compared to the GDFROM group (p<0.05). In addition, DFROM was significantly related to the LESS score and landing kinematics (p<0.05) except for total hip excursion (p=0.228). Conclusion: Our main findings showed that the LDFROM group had poorer landing quality and stiffer landing movements compared to the GDFROM group. In addition, increase of WBDF ROM significantly improved landing quality and soft-landing movements. To reduce shock during landing such as ground reaction forces, individuals need to better utilize WBDF ROM and lower extremity movements based on our findings. Therefore, intervention programs for safer landings should include exercises that increase WBDF ROM and utilize eccentric contraction.

• Korean Journal of Childcare and Education
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• v.15 no.6
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• pp.139-167
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• 2019

Objective: This study aims to investigate the effects of a learning cycle model-based early childhood education program using physical motion on young children's scientific inquiry ability, scientific attitude, object manipulation ability and spatial ability. Methods: The subjects of this study were 60 five-year-old children who were attending K-G City Childcare Center. The SPSS Window 21.0 program and content analysis method were used, and post-validation Tukey was conducted to examine the differences between the one-way ANOVA and the group. Results: Activities using body movement were practiced systematically based on the circle learning. Children could revise their pre-concept and concept of error by interacting with other children, teachers and the environment. Furthermore, children were attaining new knowledge while they were doing body movement activities, assessing and applying them to actual activities. Conclusion/Implications: This study is investigated a cyclic learning-based early childhood science education program using physical motion, which has significance in systematic and practical early childhood centered education for young children.

• Journal of The Korean Society of Integrative Medicine
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• v.6 no.1
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• pp.1-6
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• 2018

Purpose : The purpose of this study was to examine the effects of elastic taping on the power and velocity error of rectus femoris after muscle fatigue occurred. Method : The subjects of this study were 15 healthy students. The Primus RS was used to measure the power and velocity error of rectus femoris after muscle fatigue occurred. The power and velocity error were measured 3 times which are consist of pre-fatigue, after-fatigue and after 24 hours applied elastic tape on rectus femoris. A elastic tape was attached to rectus femoris between the antero inferior iliac spine (AIIS) and the tibia tuberosity. The collected data was analyzed using one-way repeated-measures ANOVA for comparison of the power and velocity error according to the measured time and Pearson test for correlation between the power and velocity error according to the measured time. Level of significance was set at 0.05. Result : No significant differences of the power and velocity error were found between $1^{st}$ and 2nd, 3rd measurements (p>.05). The power and velocity error, after 24 hours, of the applied elastic tape with muscle fatigue was significantly lower than muscle fatigue with no taping(p<.05). No significant correlations were found between the power and velocity error according to the measured time(p>.05). Conclusion : After applying the elastic tape on the rectus femoris, muscle fatigue occurred, which improved proprioception by decreasing movement error. It will be an important intervention to prevent musculoskeletal injuries and to enhance the motor control in exercise.

• Transactions of the Korean Society of Mechanical Engineers
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• v.17 no.12
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• pp.3115-3123
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• 1993

This paper presents a real-time correction method of the movemont errors of a translatory precision machine axis. This method is a null-balances technique in which two plane mirrors are used to generate an interferometric fringe pattern utilizing the optical principles of TwymanGreen interferometry. One mirror is fixed on a reference frame, while the other is placed on the machine axis being supported by three piezoelectric actuators. From the fringe pattern, one translatory and two rotational error components of the machine axis are simultaneously detected by using CCD camera vision and image processing techniques. These errors are then independently suppressed by activating the peizoelectric actuators by real-time feedback control while the machine axis is moving. Experimental results demonstrate that a machine axis can be controlled with movement errors less than 10 nm in vertical straightness, 0.1 arcsec in pitch, and 0.06 arcsec in roll for 50mm travel by adopting the real-time correction method.