• Journal of Korean Academy of Nursing
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• v.38 no.1
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• pp.11-18
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• 2008

Purpose: This study was to determine whether the Sun-style 24 forms of Tai Chi exercise improve pain, stiffness, disability, knee joint motion, mobility, balance or falling. Method: Forty-six community-dwelling elderly subjects (mean age, $75.46{\pm}6.28$) voluntarily participated in an intervention group of either 24 forms of Sun-style T ai Chi for 60 min, 2 times per week for 12 weeks or a control group. A non-equivalent pretest-posttest design was used. Independent t-test and ANCOVA were used to examine group differences by using SPSS12.0. Result: The experimental group had significantly less pain (F=7.60, p=.008) and stiffness (t=-3.19, p=.003) than the control group. Also there were significant improvements in knee joint motion on the right knee (t=2.44, p=.019), left knee (t=2.30, p=.026), rising time (F=8.03, p=.07), balance on the left single leg test (t=2.20, p=.033), and fear of falling (t=-2.33, p=.024) in the Tai Chi exercise group. No significant group differences were found in disability and falls efficacy. Conclusion: The Sun-style 24 forms Tai Chi exercise is effective in decreasing pain, stiffness, fear of falling and it improves balance, rising time, and knee joint motion. We suggest a continuing long term intervention to decrease disability and increase efficacy concerning falls.

• Korean Journal of Applied Biomechanics
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• v.33 no.3
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• pp.85-93
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• 2023

Objective: This study examined differences in joint kinematics and movement variability of lower extremity between adolescent athletes with and without lateral ankle sprain (LAS) history during drop vertical jump. Method: Fourteen adolescent athletes with LAS history and 14 controls participated in this study. The independent variable was group while dependent variables were 3D joint kinematics and movement variability of hip, knee, and ankle joint. Ensemble curve analyses were conducted to identify differences in movement strategies between two groups. Results: The LAS group showed that greater eversion during jump phase compared with the control group. Additionally, less movement variability was found in the LAS group during the pre-landing and jump phases in ankle and hip joints compared with the control group. Conclusion: The LAS group may adapt the environmental constraints by reducing the movement variability in ankle and hip joints. However, training programs focusing on recovery of ankle function should be emphasized after LAS because excessive pronation for prevention of LAS during the jump phase may result in reduced performance.

• Journal of Mechanical Science and Technology
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• v.15 no.3
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• pp.320-326
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• 2001

A Robust controller is designed for cascaded nonlinear uncertain systems that can be decomposed into two subsystems; that is, a series connection of two nonlinear subsystems, such as a robot manipulator with actuators. For such systems, a recursive design is used to include the second subsystem in the robust control. The recursive design procedure contains two steps. First, a fictitious robust controller for the first subsystem is designed as if the subsystem had an independent control. As the fictitious control, a nonlinear H(sub)$\infty$ control using energy dissipation is designed in the sense of L$_2$-gain attenuation from the disturbance caused by system uncertainties to performance vector. Second, the actual robust control is designed recursively by Lyapunovs second method. The designed robust control is applied to a robotic system with actuators, is which the physical control inputs are not the joint torques, but electrical signals to the actuators.

• Journal of the Korean Society for Precision Engineering
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• v.7 no.4
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• pp.85-102
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• 1990

Up to now, most robot control systems are very naive. They consist of a number of independent position-servo loops to control each joint angle separately. Those control systems have constant predefined gains and do not cover the complex dynamic interactions between manipulator joints. As a result, the manipulator is severely limited in range of application, speed of operation and variation of payload. This study proposed a new method to design a robot manipulator controller capable of tracking the reference trajectories of joint angles in a reasonable accuracy to cope with actual situations of varying payload, uncertain parameters. The adaptive model following control method has been used to improve existing robot manipulator controllers. The proposed controller is operated by adjusting its gains based on the response of the manipulator in such a way that the manipulator closely matches the reference model trajectories defined by the designer. The stability of adaptive controller is based on the Second Method of Lyapunov. The coupling among joints and the nonlinearity in the dynamic equation are explicitly considered. The designed manipulator controller shows good tracking performance under various load varia- tion and parameter uncertainties.

• 제어로봇시스템학회:학술대회논문집
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• 2003.10a
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• pp.2719-2724
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• 2003

In this paper, we deal with the kinematic and dynamic modeling of hybrid robotic systems that are constructed by combination of parallel and serial modules or series of parallel modules. Previously, open-tree structure has been employed for dynamic modeling of hybrid robotic systems. Though this method is generally used, however, it requires expensive computation as the size of the system increases. Therefore, we propose an efficient dynamic modeling methodology for hybrid robotic systems. Initially, the dynamic model for the proximal module is obtained with respect to the independent joint coordinates. Then, in order to represent the operational dynamics of the proximal module, we model virtual joints attached at the top platform of the proximal module. The dynamic motion of the next module exerts dynamic forces to the virtual joints, which in fact is equivalent to the reaction forces exerted on the platform of the lower module by the dynamics of the upper module. Then, the dynamic forces at the virtual joints are distributed to the independent joints of the proximal module. For multiple modules, this scheme can be constructed as a recursive dynamic formulation, which results in reduction of the complexness of the open-tree structure method for modeling of hybrid robotic systems. Simulation for inverse dynamics is performed to validate the proposed modeling algorithm.

• 제어로봇시스템학회:학술대회논문집
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• 1996.10b
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• pp.470-473
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• 1996

This paper presents an iterative learning control scheme for industrial manipulators. Based upon the frequency-domain analysis, the input update law of the learning controller is given together with a sufficient condition for the convergence of the iterative process in the frequency domain. The proposed learning control scheme is structurally simple and computationally efficient since it is independent joint control depending only on locally measured variables and it does not involve the computation of complicated nonlinear manipulator dynamics. Moreover, it is capable of canceling the unmodeled dynamics of the manipulator without even the parametric model. Several important aspects of the learning scheme inherent in the frequency-domain design are discussed and the control performance is demonstrated through computer simulations.

• Physical Therapy Korea
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• v.18 no.3
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• pp.26-37
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• 2011

Although there have been various studies related to the body's movement from a sitting to a standing position (sit-to-stand task), there is limited information on the kinematic changes on the frontal and transverse planes. The purpose of this study was to ascertain how pelvic tilt affects kinematic changes in the frontal and transverse planes in the hip and knee joints during a sit-to-stand task. For this study, 33 healthy participants (13 female) were recruited. Each participant rose from a sitting to a standing posture at his or her preferred speed for each of three different pelvic tilt trials (anterior, posterior, and neutral), and the measured angles were analyzed using a 3-D motion analysis system. A one-way repeated measure analysis of variance was performed with Bonferroni's post hoc test. In addition, an independent t-test was carried out to determine the sex differences in hip and knee joint kinematic changes during the sit-to-stand tasks. The results were as follows: 1) The hip and knee joint angle in the frontal and transverse planes showed a significant difference between the different pelvic tilt postures during sitting in the pre-buttock lift-off phase (pre-LO) (p<.05). Compared to the posterior pelvic tilt posture, the anterior pelvic tilt posture involved significantly greater hip joint adduction and internal rotation, knee joint adduction, and reduced internal rotation of the knee joint. 2) Sex differences were found with significant differences for males in the initial and maximal angles in the frontal plane of the hip and knee joint (p<.05). Females had a significantly smaller initial abduction angle of the hip joint and a significantly greater maximal angle of the hip adduction joint. These results suggest that selecting a sit-to-stand exercise for pelvic tilt posture should be considered to control abnormal movement in the lower extremities.

• Journal of the Korean Society of Physical Medicine
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• v.7 no.3
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• pp.293-302
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• 2012

Background & Purpose : The purpose of this study is to evaluate the impairment of SVMC(selective voluntary motor control) of the lower extremity by assessing each joints of lower limb and to analyze the motional relationship between each joints of lower limb using SCALE(Selective Control Assessment of the Lower Extremity) during the swing phase of gait cycle in children with spastic diplegia. Method : 11 children with spastic diplegia CP who could walk independently and 10 normal developing children were participated. SCALE(Selective Control Assessment of the Lower Extremity) assessments were conducted for 11 children with CP. Gait analysis were accomplished in all participants. Qualisys motion analysis was used as a statistical tool to assess the motional relationship between hip joint, knee joint and ankle joint in each limb. We used descriptive statistics, cross-tabulation, independent t-test, linear regression to analysis motional relationship between each joints of lower limb using by SPSS ver.17.0. Result : Firstly, there were significant differences in SCALE scores between the cerebal palsy group and the control group in knee joint(p<0.05), but no significant difference in hip and ankle joints during the swing phase of gait cycle. Secondly, the difference of SCALE scores showed no statistical motional difference in knee and ankle joints during the swing phase, and showed significant motional difference in hip joints during the swing phase(p<0.05). Thirdly, there was a liner relationship between the motion of hip and ankle joints during the swing phase. Conclusion : The nature of SVMC(selective voluntary motor control) in each joints of the lower limb may reflect the ability of gait, thus SCALE may be used for assessing and for treating the cerebal palsy patients who are able to walk independently. Also we knew that the impairment of SVMC(selective voluntary motor control) increases from the proximal to the distal joints.

• Journal of the Korean Society of Physical Medicine
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• v.14 no.2
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• pp.41-51
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• 2019

PURPOSE: This study was conducted to investigate the effects of combined Joint Mobilization and Functional Electrical Stimulation on Muscle Activation and Mobility of ankle joints in stroke patients and their Modified Functional Reach Test (MFRT) results. METHODS: A total of 26 patients with stroke were randomly selected for enrollment in this study. (1) Functional Electrical Stimulation (FES) (2) combined Joint Mobilization and FES. An EMG system was used to measure tibialis anterior and gastrocnemius activities. Range Of Motion (ROM) of Ankle Joint and MFRT for Dynamic Balance. Pre and post intervention results were compared by paired-t-tests and differences in changes after intervention between groups were identified by the independent t-test. RESULTS: The muscle activation, ROM, and MFRT differed significantly in the experimental group (p<.05). The ROM was significantly different for the active dorsiflexion pre and post intervention in the group that received FES alone (p<.05). CONCLUSION: The results of this study suggest use of a systematic program of proactive posture control to prevent dysfunction when planning interventions for ankle joints can help stroke patients walk efficiently.

• Journal of muscle and joint health
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• v.17 no.1
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• pp.25-34
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• 2010

Purpose: The aim of the present study was to examine the effects of a 4-week aromatherapy on pain and inflammation in patients suffering from rheumatoid arthritis. Methods: A quasi-experimental study using a nonequivalent control group, pretest-posttest non-synchronized design was used. To analyze the data, descriptive statistics, Chi-square test, independent samples t-test, and Fisher's exact test were used. Results: After a 4-week aromatherapy, tender joint count (M=5.67 to 4.17), swollen joint count (M=4.13 to 2.54), and patient's assessment of pain (M=43.33 to 31.08) decreased significantly for the aromatherapy participants compared to the control group. But there was no significant difference between the groups in erythrocyte sedimentation rate. Conclusion: These findings suggest that aromatherapy could decrease joint pain, tenderness, and swelling in patients with rheumatoid arthritis, but some modifications in aromatherapy intervention and research method will be required to examine the effects of aromatherapy on inflammatory level in this population.