• Journal of the Korean Society for Precision Engineering
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• v.19 no.4
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• pp.44-51
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• 2002

• Journal of Biomedical Engineering Research
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• v.31 no.4
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• pp.269-274
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• 2010

The purpose of this study was to develop the FSR sensor suit that controls walking assist device for paraplegic patients. The FSR sensor suit was to detect user's intent and patterns for walking by measuring pressure on the palm and the sole of user's foot. It consisted of four modules: sensing pressure from palm, changing modes and detecting pressure on the palm/at the wrist, sensing pressure from the soles of user's foot, and host module that transmit FSR data obtained from sensing modules to PC. Sensing modules were connected to sensing pads which detect analog signals obtained from the palm or the sole of foot. These collect signals from the target regions, convert analog signals into digital signals, and transmit the final signals to host module via zigbee modules. Finally, host modules transmit the signals to host PC via zigbee modules. The study findings showed that forces measured at the palm when using a stick reflected user's intent to walk and forces at the sole of the user's foot revealed signals detecting walking state.

• The Journal of Korea Robotics Society
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• v.12 no.2
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• pp.144-151
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• 2017

An important characteristic of people with partially impaired walking ability, such as incomplete paraplegics, is that they are able to generate voluntary motion of lower-limbs. Therefore, wearable robots for the incomplete paraplegic patients require a different assistance method compared to those of complete paraplegics. First, the wearable robot should be controlled to not resist wearer's motion. Second, it should be able to generate assistive torque accurately when needed. In this paper, a wearable robot, called EROWA, for the incomplete paraplegic patients is introduced. EROWA utilizes compact rotary series elastic actuators (cRSEAs) and a control method called the zero impedance control to reduce the mechanical resistance. An assistive torque trajectory is proposed to assist gait in this paper. The proposed method is verified by simulation and experimental studies.

• Journal of Biomedical Engineering Research
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• v.24 no.6 s.81
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• pp.523-531
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• 2003

We developed a PC-based 8-channel electrical stimulation system for transcutaneous functional electrical stimulation (FES), and applied it to FES exercise and paraplegic walking. The PC program consists of four parts: a database, a stimulation pattern generator, a stimulus parameter converter, and an exercise program. The stimulation pattern can be arbitrarily generated and edited by using the mouse on the PC screen, and the resulting stimulus parameters arc extracted from the recruitment curves, and transmitted to the 8-channel stimulator through the serial port. The stimulator has nine microprocessors: one master and eight slaves, Each channel is controlled by the slave microprocessor, and is operated independently. Clinical application of the system to a paraplegic patient showed significant increase in the knee extensor torque, the fatigue resistance, and the leg circumference, The patient can now walk about 50 meters for more than 2 minutes.

• Journal of Biomedical Engineering Research
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• v.26 no.2
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• pp.111-116
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• 2005

This study was designed to apply the stimulation system developed in our laboratory to investigate how the stimulation conditions affect the muscle contractile characteristics in the isometric condition as well as during the FES standing/walking. Four paraplegic and ten healthy subjects participated in this study, and their knee extensors were voluntary contracted or electrically stimulated to measure the muscle force and the fatigue index for different waveforms of the pulse train. We also investigated different combinations of the electrode positions during standing/walking. It was confirmed that continuous and high-frequency stimulation causes faster fatigue than intermittent and low-frequency stimulation. Fatigue resistance was higher around the optimal muscle length than at a stretched position in healthy subjects, whereas the opposite was observed in paralyzed subjects. The paired t-test results with the level of significance at 0.01 indicated that the sinusoidal waveform generated the largest torque among the four typical waveforms. Although statistically not very significant, the sinusoidal waveform also generated, in general, the highest fatigue resistance at an intensity level below the supramaximal stimulation. One of the paraplegic subject who participated in the standing/walking program can now stand up for 1 minute and 50 seconds with the knee extensors, and walk for about 5 minutes at the speed of 12m/sec.

• Journal of Biomedical Engineering Research
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• v.15 no.2
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• pp.167-174
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• 1994

In this paper, a DSP and microcomputer-based EMG controlled functional electrical stimulation (FES) system, for restoring walking of paraplegics at the patients' own command, is presented. The above-lesion EMG is a time-varying nonstationary signal and its autoregressive (AR) parameters are identified by the nonstationary identification algorithm using a DSP chip. The identified AR parameters are used for the cloassification of the function and the control of the movement. The below-lesion response-EMG signal is used as a measure of muscle fatigue. This FES system is designed to measure muscle fatigue and control the stimulation intensity according to the amplitude of the response-EMG signal. While the automatic electrical intensity control is obtained by identifying the movement, the proposed FES system is suitable for the automatic control of paraplegic walking.

• Journal of the Korean Society for Precision Engineering
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• v.25 no.8
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• pp.104-110
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• 2008

The aim of this study ultimately is verifying that PGO gait is more efficient than RGO fur paraplegics because the air muscle assists hip flexion power in heel off movement. The gait characteristics of the paraplegic wearing the PGO or RGO are compared with that of a normal person. PGO with air muscles was used to analyze the walking of patients with lower-limb paralysis, and the results showed that the hip joint flexion and pelvic tilt angle decreased in PGO. In comparison to RGO gait, which is propelled by the movements of the back, PGO uses air muscles, which decreases the movement in the upper limb from a stance phase rate of 79$\pm$4%(RGO) to 68$\pm$8%. The energy consumption rate was 8.65$\pm$3.3 (ml/min/Kg) for RGO, while it decreased to 7.21t2.5(ml/min/Kg) for PGO. The results from this study show that PGO decreases energy consumption while providing support for patients with lower-limb paralysis, and it is helpful in walking for extended times.

• Journal of Biomedical Engineering Research
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• v.19 no.1
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• pp.69-80
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• 1998

This research was designed to investigate how the exercise program affects paraplegic standing and walking employing functional electrical stimulation(FES). Emphasis was also given to fatigue of major lower extremity muscles induced by different types of electrical stimulation. We applied continuous and intermittent rectangular pulse trains to quadriceps of 10 normal subjects and 4 complete paraplegic patients. The frequencies were 20Hz and 80Hz, and the knee angle was fixed at 90$^{\circ}$and 150$^{\circ}$to investigate how muscle fatigue is related to muscle length. The knee extensor torque was measured and monitored. We have been training quadriceps and gastrocnemius of a male paraplegic patient by means of electrical stimulation for the past two year. FES standing was initiated when the knee extensors became strong enough to support the body weight, and then the patient started FES walking utilizing parallel bars and a walker. We used an 8-channel constant-voltage stimulator and surface electrodes. The experimental results indicated that paralyzed muscles fatigued rapidly around the optimal length contrary to normal muscles and confirmed that low frequency and intermittent stimulation delayed fatigue. Our exercise program increased muscle force by approximately 10 folds and decreased the fatigue index to half of the initial value. In addition, the exercise enabled the patient to voluntarily lift each leg up to 10cm, which was of great help to the swing phase of FES walking. Both muscle force and resistance to fatigue were significantly enhanced right after the exercise was applied every day instead of 6 days a week. Up to date, the patient can walk for more than two and half minutes at 10m/min while controlling the on/off time of the stimulator by pushing the toggle switch attached to the walker handle.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2004.10a
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• pp.814-817
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• 2004

It is a challenging task to make the paraplegic to walk with out the assist of the caregiver. So, we have developed various type of gait orthosis for paraplegic during the five years lately. The purpose of this study ultimately is energy consumption test of serveral type gait orthosis for developing the high efficiency gait orthosis. From the experimental results, the oxygen consumption rate were 6.9$\pm$3.3ml/kg in RGO gait, 5.3$\pm$1.3ml/kg in PGO, and 6.2$\pm$3ml/kg in HGO gait. The maximum hip flexion angle were 16$^{\circ}$ in RGO , 15$^{\circ}$ in PGO, and 47.5$^{\circ}$. in HGO. As a result It was found that. Hybrid Gait Orthosis need high energy consumption more than PGO for walking, but it is small weight and strengthened muscle.

• Journal of the Korean Society of Physical Medicine
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• v.14 no.4
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• pp.63-70
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• 2019

PURPOSE: This study examined the effects of bilateral ankle dorsiflexors-strengthening exercise on the paralytic tibialis anterior activity, balance ability, and gait function of patients with chronic stroke. METHODS: Nineteen patients with chronic stroke were assigned randomly to the experimental and control groups. All participants received general physical therapy for 60-minutes per session, five times a week, for 6 weeks. In addition, the experimental group (n = 9) performed bilateral ankle dorsiflexion muscle-strengthening training three times a week, 30 minutes per session, for six weeks. The control group (n=10) performed the paraplegic ankle dorsiflexion muscle- strengthening training in the same manner. Before and after the intervention, the paralytic tibialis anterior muscle activity, timed up and go test (TUG), and 10m walking test (10 MWT) were performed. RESULTS: Both groups showed significant improvement in the post-intervention muscle activity of the paralytic tibialis anterior, TUG, and 10MWT compared to that before the intervention (p<.05), but the differences between the two groups were not significant (p >.05). CONCLUSION: Bilateral ankle dorsiflexors strengthening exercise is an effective cross-training method to improve the muscle activity of the paraplegic tibialis anterior, balance ability, and walking function in chronic stroke patients.