• Proceedings of the KOSOMBE Conference
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• v.1998 no.11
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• pp.86-87
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• 1998

To understand the developmental process of the gait pattern from infancy to the adult, a gait analysis for a 14 months female infant has been performed for ten weeks. The gait parameters has been measured every other week since the week when she was able to walk without aid. The infant gait data at the tenth week of the test shows a similar pattern to the adult gait in many aspects including initial knee flexion, initial ankle dorsiflexion, the push-off pattern, etc. There is not a significant change in the hip flexion angle from week to week from the two weeks after the test started. To check the individuality in the collected data, more infant subjects are being tested presently.

• Proceedings of the KOSOMBE Conference
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• v.1997 no.11
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• pp.501-506
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• 1997

This is to investigate the physical properties of the commercially available Soft, Thomas, Minerva, and Philadelphia cervical braces which are widely used in orthopedics, neurosurgery, and rehabilitation medicine clinics as assisting devices or physical stabilization of cervical vertebrates, to use as a basic data or designing new type brace. Tensile strengths were observed by universal mechanical measuring device and Thomas brace required the highest stress to break by tensile stress. Durabilities against continuous frictional forces were also determined, and Minerva brace demonstrated the longest frictional time until being perforated. and Thomas/minerva braces are superior to the other braces in the effect of the material property on the skin tissue, as the animal test. According to these results, polyethylene is recommendable as a frame and preparation of pores in the material is favorable to provide ventilation to skin.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2006.05a
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• pp.645-646
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• 2006

Pressure-induced decubitus is a serious disease among the elderly people. Interface pressure occluding vascular perfusion is known to be a cause of decubitus. Therefore, it is essential to quantify the relationship between vascular perfusion and interface pressure among the elderly people. Nine elderly normal people ($57.8{\pm}5.6\;years,\;63.3{\pm}7.0kg,\;1.68{\pm}0.05m$) were participated. Pressure was applied on the ischial tuberosity in the sitting posture from 0mmHg to 135mmHg as capillary vascular perfusion was recorded. The average interface pressure to occlude vascular perfusion under the ischial tuberosity is 120mmHg. Vascular perfusion values at the capillary occlusion is often lower than 60% of the vascular perfusion at 15mmHg. Higher sampling number is required to have more accurate results.

• Proceedings of the KSME Conference
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• 2000.11a
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• pp.504-509
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• 2000

In this study, a transfemoral prosthesis system of which stance phase and swing phase are controlled during walking has been developed for the recovery of the biomechanical function of the amputated leg. It consists of a 5 bar link mechanism, a hydraulic-rubber knee damper for stance phase control and a pneumatic cylinder controlled via a microprocessor for stance phase control. The mechanical characteristics and behaviour of the knee damper which absorbs the impact energy generated at the heel contact was investigated. The characteristics of the pneumatic cylinder essential for the speed adaptation of the prosthesis during swing phase was also studied for its mechanical characteristics. The prosthesis was subject to the clinical test ant the gait characteristics obtained were very close to those of normal. The stance and swing controlled prosthesis that were developed in this study showed good stability during the stance phase and showed good controllability during the swing phase.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2002.10a
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• pp.1078-1080
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• 2002

The pressure variation of interstitial fluid is one of the most important factors in bone physiology. In order to understand the role of interstitial fluid and the biomechanical interactions between fluid and solid constituents within bone, poroelastic theory was applied. The purpose of this study is to describe the behavior of calf vertebral trabecular bone composed of the porous solid trabeculae and the viscous bone marrow by using a commercial finite element analysis program based on the poroelasticity. In this study, the model was numerically tested for 5 different strain rates, i. e., 0.001, 0.01, 0.1, 1.0, and 10 per second. The material properties of the calf vertebral trabecular bone were utilized from the previous experimental study. Two asymptotic poroelastic response, the drained and undrained deformation, were predicted. From the predicted results for the simulated five strain rate, it was found that the pore pressure generation has a linearly increasing behavior when the strain rate is the highest at 10 per second, other wise it showed a nonlinear the strain rate Increased. Based on the results of the present study, it was suggested that the calf vertebral trabecular bone could be modeled as a porous material and its strain rate dependent material behavior could be predicted.

• Journal of Biomedical Engineering Research
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• v.18 no.4
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• pp.439-446
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• 1997

We undertook this study to determine the plantar pressure distribution characteristics of hallux valgus, major increasing foot disease. Twenty three valgus Patients were evaluated with clinical examinations, radiologic studies and dynamic plantar pressure distribution measurements. The present study also suggested a masking method for detailed analyses on plantar pressure distribution measurements. With higher grade of hallux valgus, pressure, contact area, and impulse on metartasus are significantly increased Pressure concentration is very important in foot diseases and an approximate plantar pressure distribution should be considered on any shoe design.

• Journal of Biomedical Engineering Research
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• v.18 no.1
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• pp.71-78
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• 1997

Kinematic and kinetic studies were performed to investigate the walking characteristics on a treadmill with various slopes at the same speed of 1.25m/sec. Six different slopes of the treadmill were selected . -4%(-$2.3^{\circ}$), 0%($0^{\circ}$), 5%($2.9^{\circ}$), 10%($5.7^{\circ}$), 15%($8.6^{\circ}$), and 20%($11.3^{\circ}$). With increased slopes of the treadmill, both hip and knee flexion angles significantly increased at initial contact, and the maximum hip flexion during swing phase and the maximum knee flexion during stance phase also significantly increased Ankle dorsiflexion angle at initial contact and the maximum dorsiflexion increased with increased slopes. However, the maximum plantarflexion in early swing was slightly reduced with increased slopes. Hip extension in late stance and the maximum knee flexion in early swing was not changed sigilificantly with increased slopes. As for the vertical ground reaction force, compared to the yond level walking, both the first and the second peak forces increased, but the mid-support force decreased.

• Journal of rehabilitation welfare engineering & assistive technology
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• v.4 no.1
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• pp.23-28
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• 2010

Case of patients with weakness in cardiopulmonary system, other ambulatory function is normal, but oxygen supply function is problem. So they need reduce energy consumption for gait by assistance system. In this study, we designed and developed walking assistant device which helps flexion and extension of hip joint for cardiopulmonary patients. There are two motors, each at the left and right side of pelvis, providing torque to the hip joint. The target angle of the flexion and extension in the hip joint is set according to the normal gait. As a result, reduction of energy consumption was 14.8% by gait assistive device.

• Journal of Institute of Control, Robotics and Systems
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• v.12 no.9
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• pp.935-944
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• 2006

EMG pattern recognition is essential for the control of a multifunction myoelectric hand. The main goal of this study is to develop an efficient feature projection method for EMC pattern recognition. To this end, we propose a linear supervised feature projection that utilizes linear discriminant analysis (LDA). We first perform wavelet packet transform (WPT) to extract the feature vector from four channel EMC signals. For dimensionality reduction and clustering of the WPT features, the LDA incorporates class information into the learning procedure, and finds a linear matrix to maximize the class separability for the projected features. Finally, the multilayer perceptron classifies the LDA-reduced features into nine hand motions. To evaluate the performance of LDA for the WPT features, we compare LDA with three other feature projection methods. From a visualization and quantitative comparison, we show that LDA has better performance for the class separability, and the LDA-projected features improve the classification accuracy with a short processing time. We implemented a real-time pattern recognition system for a multifunction myoelectric hand. In experiment, we show that the proposed method achieves 97.2% recognition accuracy, and that all processes, including the generation of control commands for myoelectric hand, are completed within 97 msec. These results confirm that our method is applicable to real-time EMG pattern recognition far myoelectric hand control.

• Journal of Institute of Control, Robotics and Systems
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• v.15 no.2
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• pp.163-168
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• 2009

In this study, we would be developed the fuzzy controlled PGO that controlled the flexion and the extension of each PGO's hip joint using the bio-signal and FSR sensor. The PGO driving system is to couple the right and left sides of the orthosis by specially designed hip joints and pelvic section. This driving system consists of the orthosis, sensor, control system. An air supply system of muscle is composed of an air compressor, 2-way solenoid valve (MAC, USA), accumulator, pressure sensor. Role of this system provide air muscle with the compressed air at hip joint constantly. According to output signal of EMG sensor and foot sensor, air muscles and assists the flexion of hip joint during PGO gait. As a results, the maximum hip flexion angles of RGO's gait and PGO's gait were about $16^{\circ}\;and\;57^{\circ}$ respectively. The maximum angle of flexion/extention in hip joint of the patients during RGO's gait are smaller than normal gait, because of the step length of them shoes a little bit. But maximum angle of flexion/extention in hip joint of the patients during PGO's gait are larger than normal gait.