Sukmin Lee

Control of IPMC-based Artificial Muscle for Myoelectric Hand Prosthesis

This paper proposes an ionic polymer metal composite (IPMC) based artificial muscle to be applicable to the myoelectric hand prosthesis. The IPMC consists of a thin polymer membrane with metal electrodes plated chemically on both faces, and it is widely applying to the artificial muscle because it is driven by relatively low input voltage. The control commands for the IPMC-based artificial muscle is given by electromyographic (EMG) signals obtained from human forearm. By an intended contraction of the human flexor carpi ulnaris and extensor carpi ulnaris muscles, we investigated the actuation behavior of the IPMC-based artificial muscle. To obtain higher actuation force of the IPMC, the single layered as thick as 800 [mum] or multi-layered IPMC of which each layer can be as thick as 178 [mum] are prepared. As a result, the bending force was up to the maximum 12[gf| from 1[gf] by actuating the single layered IPMC with 178 [mum], but the bending displacement was reduced to 6[mm] from 30[mm]. The experimental results using an implemented IPMC control system show a possibility and a usability of the bio-mimetic artificial muscle

Effects of Progressive Body Weight Support Treadmill Forward and Backward Walking Training on Stroke Patients’ Affected Side Lower Extremity’s Walking Ability

[Purpose] The purpose of the present study was to examine the effects of progressive body weight supported treadmill forward and backward walking training (PBWSTFBWT), progressive body weight supported treadmill forward walking training (PBWSTFWT), progressive body weight supported treadmill backward walking training (PBWSTBWT), on stroke patients’ affected side lower extremity’s walking ability. [Subjects and Methods] A total of 36 chronic stroke patients were divided into three groups with 12 subjects in each group. Each of the groups performed one of the progressive body weight supported treadmill training methods for 30 minute, six times per week for three weeks, and then received general physical therapy without any other intervention until the follow-up tests. For the assessment of the affected side lower extremity’s walking ability, step length of the affected side, stance phase of the affected side, swing phase of the affected side, single support of the affected side, and step time of the affected side were measured using optogait and the symmetry index. [Results] In the within group comparisons, all the three groups showed significant differences between before and after the intervention and in the comparison of the three groups, the PBWSTFBWT group showed more significant differences in all of the assessed items than the other two groups. [Conclusion] In the present study progressive body weight supported treadmill training was performed in an environment in which the subjects were actually walked, and PBWSTFBWT was more effective at efficiently training stroke patients’ affected side lower extremity’s walking ability.

Effects of mirror therapy combined with motor tasks on upper extremity function and activities daily living of stroke patients

[Purpose] The objective of this study was to investigate the effects of mirror therapy combined with exercise tasks on the function of the upper limbs and activities of daily living. [Subjects and Methods] Twenty-five stroke patients who were receiving physical therapy at K Hospital in Gyeonggi-do, South Korea, were classified into a mirror therapy group (n=12) and a conventional therapy group (n=13). The therapies were applied for 30 minutes per day, five times per week, for a total of four weeks. Upper limb function was measured with the Action Research Arm test, the Fugl-Meyer Assessment, and the Box and Block test, and activities of daily living were measured with the Functional Independence Measure. A paired test was performed to compare the intragroup differences between before training and after four weeks of therapy, and an independent t-test was performed to compare the differences between the two groups before and after four weeks of therapy. [Results] In the intragroup comparison, both groups showed significant differences between measurements taken before and after four weeks of therapy. In the intergroup comparison, the mirror therapy group showed significant improvements compared with the conventional therapy group, both in upper limb function and activities of daily living. [Conclusion] The findings of this study demonstrated that mirror therapy is more effective than conventional therapy for the training of stroke patients to improve their upper limb function and activities of daily living.

Correlations among trunk impairment, functional performance, and muscle activity during forward reaching tasks in patients with chronic stroke.

[Purpose] This study aimed to investigate the relationships among trunk impairment, functional performance, and muscle activity during forward reaching tasks in patients with chronic stroke. [Subjects and Methods] Twenty-three chronic stroke patients participated in this study. Trunk impairment and functional performance were evaluated using the Trunk Impairment Scale, Berg Balance Scale, Timed Up and Go Test, and 10-Meter Walk Test. All subjects were asked to perform 3 different forward reaching tasks (affected side reaching, forward reaching, and less-affected side reaching), and measurements were taken during these 3 tasks by using surface electromyography. Correlation analyses were performed to assess the relationships among trunk impairment, functional performance, and muscle activity during the forward reaching tasks. [Results] Spearman’s correlation analysis revealed a strong, significant correlation between the Trunk Impairment Scale and functional performance, that was associated with balance and gait ability. During the 3 different forward reaching tasks, muscle activities of the less-affected lower extremity were significantly correlated with functional performance. [Conclusion] This study revealed the correlations among trunk impairment, functional performance, and muscle activity during forward reaching tasks in patients with chronic stroke and emphasized the importance of trunk rehabilitation.

Effects of stationary cycling exercise on the balance and gait abilities of chronic stroke patients

[Purpose] The objective of this study was to investigate the effects of stationary cycling exercise on the balance and gait abilities of chronic stroke patients. [Subjects] Thirty-two chronic stroke patients were randomly assigned to an experimental group (n=16) or a control group (n=16). [Methods] All of the subjects received the standard rehabilitation program for 30 minutes, while the experimental group additionally participated in a daily session of stationary cycling exercise for 30 minutes, 5 times per week for 6 weeks. To assess balance function, the Berg Balance Scale and timed up-and-go test were used. The 10-m walking test was conducted to assess gait function. [Results] Both groups showed significant improvements in balance and gait abilities. The improvements in the Berg Balance Scale and timed up-and-go test scores (balance), and 10-m walking test score (gait) in the stationary cycling exercise group were significantly greater than those in the control group. [Conclusion] This study demonstrated that stationary cycling exercise training is an effective intervention for increasing the balance and gait abilities of chronic stroke patients. Therefore, we suggest that stationary cycling training is suitable for stroke rehabilitation and may be used in clinical practice.

Actuation of the Artificial Muscle Based on Ionic Polymer Metal Composite by Electromyography (EMG) Signals

This article proposes an ionic polymer metal composite (IPMC) actuating system with a biomimetic function. Electromyography (EMG) signals generated by an intended contraction of muscles in the human forearm are used as controlling signals for actuating the IPMC. By controlling this with EMG signals generated from the human flexor carpi ulnaris and extensor carpi ulnaris muscles, we investigated the actuation behavior of the IPMC based on Nafion. To obtain higher actuation force of the IPMC, the single layered IPMC, as thick as 800 mm, or multi-layered IPMC of which each layer is as thick as 178 mm are prepared. The experimental results using an implemented IPMC control system show a possibility and a usability of the biomimetic artificial muscle.

Research of Elderly Gait-assistant-robot Control System

In this study, the control method of assistive robot was developed for the elderly. The control method of gait-assistant-robot was proposed considering the change of COP (Center of Pelves), BOS (Base of Support) and comparative analysis of the moving velocity for the elderly. We analyzed the movement of COP of the body and its velocity of the elderly equipped with manual walker and gait-assistant-robot. As a result, change in COP was greater from left to right than from anterior to posterior; also, the average velocity of the movement of COP and manual walker for manual walker gait was 0.7(m/s). Therefore, it is necessary to concern more on the left-right balance and synchronization of the velocity of COP.

The effects of ankle joint muscle strengthening and proprioceptive exercise programs accompanied by functional electrical stimulation on stroke patients' balance

[Purpose] The purpose of the present study was to examine the effects of ankle joint muscle strengthening and proprioceptive exercises accompanied by functional electrical stimulation on stroke patients’ balance ability. [Methods] For six weeks beginning in April 2015, 22 stroke patients receiving physical therapy at K Hospital located in Gyeonggi-do were divided into a functional electrical stimulation (FES), ankle proprioceptive exercise and ankle joint muscle strengthening exercise group (FPS group) of 11 patients and an FES and stretching exercise group (FS group) of 11 patients. The stimulation and exercises were conducted for 30 min per day, five days per week for six weeks. Balance ability was measured using a BioRescue and the Berg balance scale, functional reach test, and the timed up-and-go test were also used as clinical evaluation indices. Repeated measures ANOVA was conducted to examine differences between before the exercises and at three and six weeks after beginning the exercises within each group, and the amounts of change between the two groups were compared. [Results] In the comparison within each group, both groups showed significant differences between before and after the experiment in all the tests and comparison between the groups showed that greater improvement was seen in all values in the FPS group. [Conclusion] In the present study, implementing FES and stretching exercises plus ankle joint muscle strengthening and proprioceptive exercises was more effective at improving stroke patients balance ability than implementing only FES and stretching exercises.

Therapeutic effects of reaching with forward bending of trunk on postural stability, dynamic balance, and gait in individuals with chronic hemiparetic stroke

[Purpose] The objective of this study was to perform forward bending of the trunk and reaching training in chronic stroke patients and to investigate subsequent changes in trunk control, dynamic balance, and gait. [Subject] Twenty-three chronic stroke patients were randomly divided into two groups, with 10 patients in the forward bending of the trunk and reaching group and 13 patients in the control group. [Methods] Both groups underwent 30 minutes of rehabilitation therapy, five days a week, for four weeks. The forward bending of the trunk and reaching group additionally performed forward bending of the trunk and reaching training five times a week for four weeks, which involved four sets of pressing buttons 35 times, for a total of 140 button presses per session. The subjects were tested before and after training using the Trunk Impairment Scale, Berg Balance Scale, Timed Up and Go Test, Six-Minute Walking Test, and 10-Meter Walking Test. Trunk control, dynamic balance, and walking ability were compared between the two groups. [Result] The results of the study showed that the results of the Trunk Impairment Scale, Berg Balance Scale, Timed Up and Go Test, Six-Minute Walking Test improved significantly in the FBR group, while there were no significant differences in the control group. [Conclusion] This study results suggest that forward bending of the trunk and reaching training can be an effective exercise method for chronic stroke patients.

Study on the Characteristics of the Absorbency Silicone by Super Absorbent Polymers

ABSTRACT ：Silicone resin has no water-absorbing function because it is a strong hydrophobic polymer. However, additionof super absorbent polymer gives much better absorbency than that of conventional silicone resin. In this study, we developednovel silicone materials with water-absorbing function by choosing three types of amorphous acrylic super absorbent polymerswith different particle sizes, determining the mixing ratio of the three polymers and applying the mixtures into two-componenttype silicone material for medical purpose. The change in the mechanical properties such as tensile strength, tear strength, compressive strength and hardness was investigated by varying the particle size and content ratio of the added super absorbentpolymers while preparing the silicone resins. The absorbency of the silicone resins was measured over time. Additionally, the particle shape of the super absorbent polymers as well as the distribution within the silicone resin was observed using an optical microscope.