• Journal of rehabilitation welfare engineering & assistive technology
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• v.8 no.4
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• pp.283-289
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• 2014

This paper presents a design and optimization of the fully-active transfemoral prosthesis leg system. As it has one degree of freedom in knee joint, this prosthesis leg can imitate the human's gait. The weight of system, which makes the users more comfortable due to less tiredness, and the knee joint torque to rise stability of the system are major factors of prosthesis leg system. Thus the mechanism of prosthesis changes from 3-linkage type to geared type. The sensorized foot is also designed to effectively determine human's gait by measuring deformation of the foot during gait. Topology optimization is carried out for the sensorized foot to remove its unnecessary weight. The safety of optimized foot is verified by carrying out finite element analysis.

• Journal of the Korean Society for Precision Engineering
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• v.33 no.3
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• pp.173-181
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• 2016

This paper reports on the development of a roller-cam clutch mechanism. This mechanism can transfer bidirectional torque with high backdrivability, as well as increase actuation energy efficiency, in electrical exoskeleton robots. The developed mechanism was installed at the robot knee joint and unclutched during the swing phase which uses less metabolic energy, thereby functioning as a passive joint. The roller-cam clutch aimed to increase actuation energy efficiency while also producing high backdrivability by generating zero impedance for users during the swing phase. To develop the mechanism, mathematical modeling of the roller-cam clutch was conducted, with the design having more than three safety factors following optimization. Titanium (Ti-6AL-4V) material was used. Finally, modeling verification was done using ANSYS software.

• Journal of Biomedical Engineering Research
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• v.31 no.3
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• pp.217-226
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• 2010

The lower limb orthosis with a pneumatic rubber actuator, which is intended for the assistance and the enhancement of muscular activities of lower limbs was developed in this study. Compared to other knee extension assistive devices being developed by other researchers, our device is designed especially for the elderly people and intended only for slight assistance so that the subjects can keep their muscular strength. For the effectiveness of system, muscular activities of major muscles in lower limbs during sit-to-stand (STS) and squat motion were measured and analyzed. Subjects were performed the STS and squat motion with and without lower limb orthosis. We made comparison muscular activities between with and without lower limb orthosis. Lower limb orthosis was controlled using muscular stiffness force feedback that is controlled by muscular activities of the measured muscle from force sensor. For analysis of muscular activities, electromyography of the subjects was measured during STS and squat motion, and these were measured using MP 150(BIOPAC Systems, Inc.). Muscles of interest were rectus femoris(RF), vastus lateralis(VL), vastus medialis(VM) and vastus intermedius(VI) muscles in lower limbs of the right side. A biodex dynamometer was used to measure the maximal concentric isokinetic strength of the knee extensors of wearing and not wearing orthosis on right side. The test were performed using the concentric isokinetic mode of test with the velocity set at 60°/s for muscles around the knee joints. The experimental result showed that muscular activities in lower limbs wearing orthosis using muscular stiffness force of a vastus medialis muscle was reduced and knee extension torque of an knee joint wearing lower limb orthosis was increased. With this, we confirmed the effectiveness of the developed lower limb orthosis.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.17 no.8
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• pp.46-54
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• 2016

This study was conducted to investigate the effects of participation in the accelerated rehabilitation with an anti-gravity treadmill program for 16 weeks on isokinetic myofunction and functional score of knee joint, ROM, and VAS score in meniscus repair patients. A total of 10 male adult patients who underwent meniscus repair by the same doctor were investigated in this study. Both extension and flexion peak torque at $60^{\circ}/sec$ and $180^{\circ}/sec$ significantly increased (p<0.001, p<0.01), while under muscle deficit, extension and flexion peak torque at $60^{\circ}/sec$ and extension peak torque at $180^{\circ}/sec$ significantly decreased (p<0.01, p<0.05). ROM in extension significantly decreased (p<0.05), whereas ROM in flexion significantly increased (p<0.01) in response to the program. VAS score significantly decreased (p<0.001) and lysholm scores significantly increased after completion of the program (p<0.001). These results suggest that 16 weeks of the anti-gravity treadmill accelerated rehabilitation program improves isokinetic muscle strength and functional score of knee joint, ROM, and VAS score in meniscus repair patients. Therefore, the anti-gravity treadmill accelerated rehabilitation program, which is a more scientific and effective method than conventional rehabilitation, leads to faster recovery of paly ground and normal daily activities.

• Journal of Life Science
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• v.12 no.6
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• pp.780-785
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• 2002

The purpose of this study is to investigate isokinetic strength changes of knee joint in accordance with short-term weight loss of wrestlers. For this purpose, 14 male wrestlers of a K technical high school in B city participated in our research. The wrestlers were divided into two groups; one group of the wrestlers didn't lose any weight, and the other lost over 5% of their weights. The isokinetic strength was also observed before and after weight loss. The isokinetic strenght test were processed at test speed of the$60^{\circ}C$/sec, $90^{\circ}C$/sec, and $250^{\circ}C$/sec with the CYBEX NORM system(Cybex 770＋TMS, USA). Peak torque, peak torque %BW, total work, total work %BW, and endurance ratio were measured. Results showed that the isokinetic strength after the short-term weight loss of wrestlers decreased meaningfully Although endurance ratio didn't show any meaningful difference in our research, but more accurate research may find out the relationship between short-term weight loss and the endurance ratio of isokinetic strength.

• Journal of the Korea Convergence Society
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• v.11 no.5
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• pp.175-182
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• 2020

The calculation of the optimal trajectory of the stepped top-down robot was made using a genetic algorithm and a computational torque controller. First, the total energy efficiency was minimized using the Red-Cold Generic Algorithm (RCGA) consisting of reproductive, cross, and mutation. The reproducibility condition related to the position assembly of the start and end of the stride and the joints, angles, and angular velocities are linear constraints. Next, the unequal constraint accompanies the condition for preventing the collision of the swing leg at the corner with the outer surface of the stairs, the condition of the knee joint for preventing kinematic peculiarity, and the condition of no moment in safety in the traveling direction. Finally, the angular trajectory of each joint is defined by fourth-order polynomial whose coefficient is to approximate chromosomes. This is to approximate walking. In this study, the energy efficiency of the optimal trajectory was analyzed by computer simulation through a biped robot with seven degrees of freedom composed of seven links.

• Journal of Biomedical Engineering Research
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• v.16 no.2
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• pp.217-222
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• 1995

We propose some applications of image processing techniques to extract quantitative measurements by using a camera system developed in Korea university and Catholic Medical School. From now on the system will be called as KCMOTION. The purpose of this study is to provide basic kinematic and kinetic data for the analysis of human movements and to find the clinical usefulness and reliability of the proposed motion analysis system. Two tests, sit-to-stand (STS) movements and pendulum test, are conducted by the system. The aims of the tests are to identify variability and reliability of KCMOTION to give some quantitative comparisons to the other systems. The result of STS movement are compared to the LOCUS IIID motion analyzer by the ratio of maximum flexion movement per body weight to the actual maximum flexion extension torque per body weight. That result in 29 % and 33 % for hip and knee joint, respectively in KCMOTION and 27 % and 30 % in LOCUS IIID System. The results of the pendulum movements are compared to that of using Cybex and Electrogoniometer with relaxation index, amplitude ratio, swing number and swing time. The results of relaxation index and amplitude ratio of the KCMOTION are between those of the Cybex and Electrogoniometer. We also observed that the KCMOTION detect more natural movement, from the results of swing number and time.

• Journal of the Korean Society for Precision Engineering
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• v.26 no.7
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• pp.142-149
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• 2009

The aim of this study was to identify both the mechanical and reflex properties associated with spasticity in hemiplegic patients. Ten hemiplegic patients were included in this study. Multiple pendulum tests were executed for each subject, and knee joint angle and EMG of Rectus Femoris muscle were measured. The neuromusculoskeletal system model was developed from generally accepted mechanism and identified through minimization of the error in the model-predicted pendulum trajectories. The identification was successful in terms of small error in simulated kinematics and high sensitivity and precision of simulated torque against EMG activity. The reflex threshold showed significant difference between different clinical scores (p<0.01) and significant negative correlation (r=-0.93) with the EMG duration. It is expected that the suggested method may help in understanding mechanisms underlying spasticity.

• Proceedings of the KSME Conference
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• 2008.11a
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• pp.1461-1466
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• 2008

In the case of Posterior Cruciate Ligament (PCL), the most frequent mechanism is the dashboard injury, which is directly pressurized to the anterior of the proximal tibia in the state of the knee hyperflexion. The PCL associated ligament damage happens when the posterior injury, the varus, the valgus, the hyperextension and the severe vagus torque are out of the critical value of PCL. After the successful operation cases of Anterior Cruciate Ligament (ACL) reconstruction using the allograft were informed from 1986, a number of results kept over the maximum 10 years were reported. Unfortunately, PCL reconstruction are crowded the surgery techniques such as the graft, the tibia fixing method, the fixation device, the location of the femoral tunnel, the number of the graft bundles and PCL reconstruction to access to the stability of the normal joint is being developed. Therefore, this study is the basic research of these above facts. The current transtibial tunnel surgery using the cadaveric Achilles tendon grafts is chosen for the various PCL reconstruction. The initial extension of the Achilles tendon by the fixing device and its location under the cyclic loading, were observed.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.14 no.1
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• pp.229-238
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• 2013

The aim of this study is to evaluate university canadian paddlers' iso-kinetic muscle function and provide training advices. Eight university paddlers with a 8.5 years career participated in this study. Inbody 720, biodex system III, biodex stabilizer system and THP 2 are used to investigate body component, muscle function(peak torque, average power and work fatigue), agility and dynamic balance. Iso-kinetic muscle function around shoulder, thorax and knee are measured. And then bilateral and unilateral muscle imbalance are calculated at each joint. Results of this study are as follows; University canadian paddlers' BMI average is 24.90 $kg/m^2$ and percent body fat is 12.23%. Reaction time average was 324 msec and balance score at each leg are below 2.0. A3, A4, A5, A6, A8 are needed to train shoulder muscle strength and power. A1, A2, A7, A8 are needed to strengthen shoulder muscle endurance. A2, A5, A8 are needed to train thorax muscle strength and power. A1, A8 are needed to strengthen thorax muscle endurance. Most of paddlers' reciprocal muscle balance ratio on thorax and knee are out of normal range. A2, A3, A4, A8 are needed to train abdominal strength and A3, A5, A6, A7, A8 are needed to train hamstring strength.