Mu-Seong Mun’s research while affiliated with Incheon Medical Center and other places

The aims of this study were to evaluate the joint coordination between hip and knee joints in the transfemoral amputees, and its symmetry between sound and prosthetic limbs. Seven transfemoral amputees (46.4?10.7-year-old, 174.8?3.5cm, 78.3?9.7kg) and 7 able bodies (24.0?4.5-year-old, 174.5?5.9cm, 66.9?9.4Kg) participated in this study. They walked at a self-selected walking speed across a 10m level ground. Simultaneously angle and angular velocity in the hip and knee joint were measured by motion analysis system. Then continuos relative phase(CRP), standard deviations of CRP (CRP_SD) and symmetry index(SI) were calculated. In able bodies, there were no differences of the parameters between left and right limb(all p>0.05). However, significant differences between sound and prosthetic limb in most of the parameters, except for CRP for stance phase were shown (all p

Recently, due to increasing aging population, there has been increased interest and demand for electric powered wheelchairs. However, generally, they are considerably large or heavy to be transported by a vehicle. In order to improve this problem, a power add-on drive wheelchair(PADW) has been developed by combining the advantages of a manual wheelchair and a powered wheelchair. In particular, a study of in-wheel motor has been an important issue to develop a light weight powered wheelchair since the volume and the weight of the wheelchair can be minimized by containing many mechanical elements such as motor, brake, reducers and etc. inside of a wheel hub. In this study, the design specification of a driving motor for a PADW is determined via modeling, and a light-weight wheelchair is developed by adopting an in-wheel motor that is detachable from the wheelchair and allows conversion between the manual and the powered modes freely. Further, through the various experiments, the performance of the developed PADW was evaluated.

Determining of the exercise intensity is very important in terms of induction of low fatigue during exercise. Little information is available on the contraction level of the trunk muscles during whole body tilts with and without axial rotation. This study was to investigate the difference muscle activation level according to axial rotation. Twenty subjects were participated. The muscle activities of the five trunk muscles were bilaterally measured at eight axial rotation angles with 12 tilt angles along 15^{\circ} intervals. The results showed that tilt with 45^{\circ} axial rotation was more balanced in the same tilt angle and was maintained approximately level of 40% MVC at over 60^{\circ} tilt angle with respect to co-contraction of abdominal and back muscle. Lumbar stabilization exercise using whole body tilts would be more effective with axial rotation than without axial rotation in terms of muscle co-contraction.

The anti-gravity gait training system is a rehabilitation training device for patients with neurological impairments and elderly people having problems with walking. We are developing a unloading body weight device for the gait training system. Unloading device is a necessary part because the user of this system have a muscular skeletal weaknesses. We want to control the unloading forces to be steady because the physiological gait pattern can be obtained in this condition only. We have developed the simulation model of gait training system, a human dummy models, various traditional unloading devices and the controlled unloading device. Simulation model will be used for designing a novel controller and mechanism of unloading system.

An essential consideration to differentiate prosthetic hand from robot hand is its convenience and usefulness rather than high resolution or multi-function of the robot hand. Therefore, this study proposes a myoelectric hand with a 2 DOF auto wrist module which has 6 essential functions of the human hand such as open, grasp, pronation, supination, extension, flexion, which improves the convenience of the daily life. It consists of the 3 main parts, the myoelectric sensor for input signal without additional attachment to operate the prosthetic hand, hand mechanism with high-torqued auto-transmission mechanism and self-locking module which guarantee the safety under the abrupt emergency and minimum power consumption, and dual threshold based controller to make easy for adopting the multi-DOF myoelectric hand. We prove the validity of the proposed system with experimental results.

The recent power add-on drive wheelchairs (PADWs) provide greater physical activity and easier transportability and may be an excellent alternative for the typical manual and powered wheelchairs. The driving system consists of a motor and a motor driver is the most important component of the PADW In this paper, design, implementation, and testing of a driving system for a PADW are presented. To design the output power and torque for the driving system, the equation of motion has been investigated. The motor and driver were fabricated with precise machining and assembled to implement our prototype driving system. The dynamometer test has been carried out using the prototype in order to examine the torque of the system. The experimental results demonstrates that the designed driving system can provide enough output power and efficiency for utilization in a PADW.

Although prosthetic training was received, most of amputees mainly depend on visual feedback to use prostheses, not on cutaneous and proprioceptive sensibility. Our objective of this study was to determine if there are changes in the somatosensory sensibility of amputees compared to non-amputees using multi-channel vibration stimulation system. One transradial amputees and ten non-amputees were involved. To investigate changes of residual somatosensory sensibility at stump, we set up custom-made vibration stimulation system including eight actuators (4 medial and 4 lateral) and GUI-based acquisition system. The results showed that there was similar pattern of subjective response at most of channels among group as stimulation increases. However, amputees' subjective response at channel 8 for 238Hz vibration was more sensitive than that of healthy persons. With respect to channels, response at channel 4 (medial) corresponding region to flexor carpi ulnaris for transradial amputees was most sensitive than other channels. In addition, sensitivity of four medial channels was on average about 0.5 scale than that of four lateral channels. Somatosensory sensibility was amputee, women, and men in sensibility order.

In this study, the control method of assistive robot was developed for the elderly. The control method ofgait-assistant-robot was proposed considering the change of COP (Center of Pelves), BOS (Base of Support) and comparativeanalysis of the moving velocity for the elderly. We analyzed the movement of COP of the body and its velocity of the elderlyequipped with manual walker and gait-assistant-robot. As a result, change in COP was greater from left to right than fromanterior to posterior; also, the average velocity of the movement of COP and manual walker for manual walker gait was0.7(m/s). Therefore, it is necessary to concern more on the left-right balance and synchronization of the velocity of COP.

This study examined the differences in spatio-temporal parameters, joint angle, ground reaction force (GRF), and joint power according to the changes of gait speed for trans-tibial amputees to investigate the features of the energy-storing foot for sports. The subjects walked at normal speed and at fast speed, wearing a single-axis type foot (Korec) and an energy-storing foot for sports (Renegade) respectively. The results showed that Renegade yielded faster gait speed as well as more symmetric gait pattern, compared to Korec. However, as gait speed was increased, there was no significant difference in kinematics, ground reaction force, and joint power between two artificial foots. This was similar to the results from previous studies regarding the energy-storing foot, where the walking velocity and gait symmetry have been improved. Nevertheless, the result of this study differed from the previous ones which reported that joint angle, joint power, and GRF increased as the gait speed increased except spatio-temporal parameters.

This paper suggest a prototype of a 3 degree of freedom myoelectric hand system for the upper limb amputee. It is consists of the 3 main part, the myoelectric sensor, the myoelectric hand, and training system: the first is a surface electrode myoelectric sensor to extract the raw electromyogram signal from the residual muscle of the upper limb amputee. To implement 6 essential function of the hand, three sensors are attached to the residual muscle. The next is a 3 degree of freedom myoelectric hand itself which alternates the role of the hand of the upper limb amputee. The final is training system which help the upper limb amputee to be well adapted with repetitive rehabilitation. We prove the validity of the system with experiment.