• Transactions of the Korean Society of Mechanical Engineers A
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• v.39 no.6
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• pp.617-624
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• 2015

This paper describes the development of a wearable robot to assist the elbow muscle for use by elderly workers in aging societies. Various previously developed wearable robots have drawbacks in terms of their price, portability, and slow recognition of the wearer's intention. In this paper, emphasis is placed on the following features to minimize these drawbacks. The first feature is that an actuator is attached only at the elbow joint that withstands the highest moment during arm motion to reduce the weight, volume, and price of the robot and increase its practicality. The second is that operation of the wearable robot is divided into two modes, a tracking mode and a muscle strengthening mode, and the robot can automatically switch between these modes by analyzing the wearer's intention through the brachial muscle strength measuring device developed in this study. The assistive performance of the developed wearable robot is experimentally verified by motion tracking experiments without an external load and muscle strengthening experiments with an external load. During the muscle strengthening experiments, the power of the muscle of the upper arm is measured by a commercial electromyography (EMG) sensor. Motion tracking performance at a speed of $120^{\circ}/s$ and muscle assistance of over 60 % were obtained using our robot.

• Journal of Mechanical Science and Technology
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• v.19 no.3
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• pp.778-791
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• 2005

A novel pneumatic artificial muscle actuator (PAM actuator), which has achieved increased popularity to provide the advantages such as high strength and high power/weight ratio, low cost, compactness, ease of maintenance, cleanliness, readily available and cheap power source, inherent safety and mobility assistance to humans performing tasks, has been regarded during the recent decades as an interesting alternative to hydraulic and electric actuators. However, some limitations still exist, such as the air compressibility and the lack of damping ability of the actuator bring the dynamic delay of the pressure response and cause the oscillatory motion. Then it is not easy to realize the performance of transient response of pneumatic artificial muscle manipulator (PAM manipulator) due to the changes in the external inertia load with high speed. In order to realize satisfactory control performance, a variable damper-Magneto­Rheological Brake (MRB), is equipped to the joint of the manipulator. Superb mixture of conventional PID controller and a phase plane switching control method brings us a novel controller. This proposed controller is appropriate for a kind of plants with nonlinearity, uncertainties and disturbances. The experiments were carried out in practical PAM manipulator and the effectiveness of the proposed control algorithm was demonstrated through experiments, which had proved that the stability of the manipulator can be improved greatly in a high gain control by using MRB with phase plane switching control method and without regard for the changes of external inertia loads.

• 제어로봇시스템학회:학술대회논문집
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• 2005.06a
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• pp.1983-1989
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• 2005

Industrial robots are powerful, extremely accurate multi-jointed systems, but they are heavy and highly rigid because of their mechanical structure and motorization. Therefore, sharing the robot working space with its environment is problematic. A novel pneumatic artificial muscle actuator (PAM actuator) has been regarded during the recent decades as an interesting alternative to hydraulic and electric actuators. Its main advantages are high strength and high power/weight ratio, low cost, compactness, ease of maintenance, cleanliness, readily available and cheap power source, inherent safety and mobility assistance to humans performing tasks. The PAM is undoubtedly the most promising artificial muscle for the actuation of new types of industrial robots such as Rubber Actuator and PAM manipulators. However, some limitations still exist, such as the air compressibility and the lack of damping ability of the actuator bring the dynamic delay of the pressure response and cause the oscillatory motion. In addition, the nonlinearities in the PAM manipulator still limit the controllability. Therefore, it is not easy to realize motion with high accuracy and high speed and with respect to various external inertia loads in order to realize a human-friendly therapy robot To overcome these problems a novel controller, which harmonizes a phase plane switching control method with conventional PID controller and the adaptabilities of neural network, is newly proposed. In order to realize satisfactory control performance a variable damper - Magneto-Rheological Brake (MRB) is equipped to the joint of the manipulator. Superb mixture of conventional PID controller and a phase plane switching control using neural network brings us a novel controller. This proposed controller is appropriate for a kind of plants with nonlinearity uncertainties and disturbances. The experiments were carried out in practical PAM manipulator and the effectiveness of the proposed control algorithm was demonstrated through experiments, which had proved that the stability of the manipulator can be improved greatly in a high gain control by using MRB with phase plane switching control using neural network and without regard for the changes of external inertia loads.

• Korean Journal of Applied Biomechanics
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• v.19 no.4
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• pp.697-705
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• 2009

The purpose of this study is to elucidate the possible cause of falling owing to mechanical energy in elderly women as compared to young women when performing the sit-to-walk movement. Two groups participated in this study: 10 elderly women and 10 young women. We used a ProReflex MCU camera (Qualisis, Sweden) and ground reaction force to evaluate the mechanical work. The muscle power (W) showed the same low negative work in both groups in the extension phase of the knee and hip joints while varying the angular velocity and net muscle moment of force. Elderly women, in particular, showed lower negative work. In mechanical work (J), the knee and hip joints of both groups showed the same amount of negative work in the extension phase. In the hip joint, elderly women showed lower negative work results in each phase. These result showed the possible reasons of falling for elderly women according to the weakness of the thigh muscle of the hip joint during the sit-to-walk movement.

• The Korean Journal of Rehabilitation Nursing
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• v.3 no.1
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• pp.108-117
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• 2000

Stroke is one of the leading causes of death in Korea. Because of their sequelae, strokes are categorized as a sudden-onset, constant course chronic illness which needs continuous efforts for rehabilitation. Unfortunately, there are few community based rehabilitation program for post-stroke patients who stay at home. The authors developed a community based selp-help management program for post-stroke patients to enhance their rehabilitation process. The program consists of five sessions and each session contains health education. ROM exercise, ADL training, and stress management like foot reflexology. A professor and two graduate students of nursing college coordinated the program. To test the effects of the program we conducted a 5 week program to the 10 conveniently selected post-stroke patients who were living in Kang-buk district of Seoul. The Questionnaires about ADLs, IADLs, depression and life satisfaction were asked to the all subjects before and after program. The hand grisp power and muscle strength of four limbs were measured at the end of each sessions. The analysis of data revealed that the program was effective to increase the ADLs, IADLs, and muscle strength and to decrease the depression levels of subjects. However, there was no significant difference between pre and post hand grisp power and life satisfaction. Because the program was effective to Improve the physical and psycholocial function of subjects, we suggest continual development and Implementation of community based self-help management programs.

• Journal of rehabilitation welfare engineering & assistive technology
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• v.7 no.2
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• pp.101-107
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• 2013

In this paper, we were to investigate effect of correction to muscle imbalance in lower limbs according to reduction of weight bearing methods of four point of horizontal shaft using two-belt treadmill. Participants were divided to two group according to each ten peoples who have difference of muscle function in left and right legs over 20%. Experiment progressed forty minutes a day three days a week, total four weeks and we estimated the maximal peak torque and average power for testing joint torque in hip, knee and ankle. The results showed that the correction effect of muscle imbalance to the maximal muscle strength was the most effective in hip joint. Also in knee joint, correction effect of muscular reaction was the most effective too. We thought that reduction of weight bearing methods could be positive effect to correct muscle imbalance in lower limbs.

• Physical Therapy Korea
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• v.23 no.2
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• pp.84-92
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• 2016

Background: Strengthening the supraspinatus is an important aspect of a rehabilitation program for subacromial impingement and tendinopathy. Many authors recommended empty-can (EC), full-can (FC), and prone full-can (PFC) exercises to strengthen the supraspinatus. However, no ultrasonography study has yet investigated supraspinatus muscle architecture (muscle thickness; MT, pennation angle; PA, fiber bundle length; FBL) in relation to supraspinatus strengthening exercises. Objects: The purpose of this study was to compare the architecture (MT, PA, and FBL) of the supraspinatus muscle during three different types of exercises (EC, FC, and PFC) using diagnostic ultrasound. Methods: Participants performed three different exercises: (A) EC; the arm was maintained at $60^{\circ}$ abduction with full internal rotation in the sitting position, (B) FC; the arm was maintained at $60^{\circ}$ abduction with full external rotation in the sitting position, and (C) PFC; the arm was maintained at $60^{\circ}$ abduction with full external rotation in the prone position. Ultrasonography was used to measure the MT, PA and FBL of the supraspinatus. One-way repeated analysis of variance with Bonferroni's post-hoc test was used to compare between the three exercises and the initial position of each exercise. Results: Compared with each initial position, the FC exercise showed the greatest mean difference in muscle architecture properties and the PFC exercise showed the least mean difference. Conclusion: The findings suggest that the FC exercise position may have an advantage in increasing the amount of contractile tissue or producing muscle power and the PFC exercise position may be useful in a rehabilitation program because it offers the advantage of maintaining the muscle architecture properties.

• Korean Journal of Applied Biomechanics
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• v.17 no.4
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• pp.181-190
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• 2007

The purpose of this study was to analyze the muscle fatigue for lower limbs during the level and downhill running. The subjects were 6 males of twenties who have no experience to get the injury in the lower limbs and required to run on the level and downhill which was -7% grade treadmill at 8.3km/h. EMG signal was gained by ME3000P8 Measurement Unit and computed the Median Frequency(MF) with the power spectrum analysis in the Megawin software. Rectus femoris(RF), Vastus lateralis(VL), Gluteus medius(GLU), Biceps Femoris(BF), gastrocnemius medial head(GM), gastrocnemius lateral head(GL), Tibialis anterior(TA) were selected. The result of this study were as follows: The MF of RF decreased in the downhill running than level running in length of time but, the MF of VL was opposite. The MF of BF decreased in the level and downhill running, but, the MF of BF decreased much in the level than downhill running. The MF of GLU decreased much in the downhill running but, almost no change in the level running. The MF of TA decreased in the level running than downhill running. The MF of GL decreased in the level running but, the MF of GM decreased in the downhill running in length of time. This study analyzed the muscle fatigue of the lower limbs with the median frequency on the basis of an assumption that the impact force for the flexion and extension of the joint and the body mass may be much in the eccentric contraction such as the downhill running than level running. RF and GM showed the muscle fatigue in the downhill running than level running. BF and GL showed the muscle fatigue in the level running than downhill running.

• Journal of Korean Medicine Rehabilitation
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• v.20 no.3
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• pp.37-60
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• 2010

Objectives : The purpose of this study was to investigate the relationship between masseter and cervical muscle activity and temporomandibular disorder in female office workers. Methods : Experimental group of 24 healthy subjects complained of temporomandibular joint related to computer use which lasted more than 3 months in the past year and was present in the past 7 days as well as on the day of test. Control group of 20 healthy subjects had no complaints of minimal discomfort on the day of test, and had no discomfort in the past 7 days. If they had reported discomfort in the past 12 months, it was of a short duration(<3 months) and resolved at least 3 months prior to participation. Outcomes were assessed by meridian-electromyography(MEMG), whole spin x-ray, mandibular function impairment questionnaire(MFIQ), neck disability index(NDI), visual analog scale(VAS), Beck depression inventory(BDI), stress reaction inventory(SRI) and Holmes & Rahe social readjustment rating scale(SRRS). Results : The contraction power of masseter muscle, upper trapezius, sternocleido-mastoid muscle and erector spinae by MEMG was significantly higher in the experimental group. The muscle fatigue of masseter muscle and sternodeido-mastoid muscle by MEMG was significantly higher in the experimental group. SRI was significantly higher in experimental group. There was no significant difference between two groups in the Jackson's angle, Cobb's method and cranio-cervical posture. Conclusions : The results suggest that temporomandibular disorder related mental stress but physical stress does not change cervical structure significantly.

• The Journal of Korean Academy of Orthopedic Manual Physical Therapy
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• v.13 no.2
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• pp.55-68
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• 2007

Object: to evaluate the effects of two different treatments-joint mobilization and therapeutic exercise on difference for length of lower limbs. Method: The subjects were participated twenty six who has difference for length of lower limbs more 10mm. All subjects randomly assigned to Joint mobilization group(n=13) and therapeutic exercise group. Joint mobilization group received joint mobilization for 2 minutes, Therapeutic exercise group received for 15 minutes per day and 3 times a week during 4 week period. Tape measure method was used to measure the difference for length of lower limbs. Biodex was used to measure the muscle power of lower limbs(Knee flexion, extension). Finger to floor test was used to measure the mobility of spinal column. All measurement of each subjects were measured at pre-experiment, after 2weeks and post-experiment. Result: The result of this study were summarized as follows : 1. Both treatment decreased difference for length of lower limbs while joint mobilization more decreased difference for length of lower limbs than therapeutic exercise. 2. Both treatment increased mobility of spinal column while joint mobilization more increased mobility of spinal column than therapeutic exercise. 3. Joint mobilization increased muscle power while therapeutic exercise decreased muscle power. Conclusion: in a group-wise comparison joint mobilization is more effective than therapeutic exercise.