• Journal of Information Processing Systems
• /
• v.15 no.4
• /
• pp.957-966
• /
• 2019

This paper studies a novel approach to natural gait cycles based gait recognition via kernel Fisher discriminant analysis (KFDA), which can effectively calculate the features from gait sequences and accelerate the recognition process. The proposed approach firstly extracts the gait silhouettes through moving object detection and segmentation from each gait videos. Secondly, gait energy images (GEIs) are calculated for each gait videos, and used as gait features. Thirdly, KFDA method is used to refine the extracted gait features, and low-dimensional feature vectors for each gait videos can be got. The last is the nearest neighbor classifier is applied to classify. The proposed method is evaluated on the CASIA and USF gait databases, and the results show that our proposed algorithm can get better recognition effect than other existing algorithms.

• Korean Journal of Applied Biomechanics
• /
• v.26 no.3
• /
• pp.249-255
• /
• 2016

Objective: This purpose of this study was to analyze the relationship between dimensionless leg stiffness and kinetic variables during gait performance, and its modulation with body weight. Method: The study sample consisted of 10 young women divided into 2 groups (Control, n=5 and Obese, n=5). Four camcorders (HDR-HC7/HDV 1080i, Sony Corp, Japan) and one force plate (AMTI., USA) were used to analyze the vertical ground reaction force (GRF) variables, center of pressure (COP), low limb joint angle, position of pelvis center and leg lengths during the stance phase of the gait cycle. Results: Our results revealed that the center of mass (COM) displacement velocity along the y-axis was significantly higher in the obese group than that in control subjects. Displacement in the position of the center of the pelvis center (Z-axis) was also significantly higher in the obese group than that in control subjects. In addition, the peak vertical force (PVF) and dimensionless leg stiffness were also significantly higher in the obese group. However, when normalized to the body weight, the PVF did not show a significant between-group difference. When normalized to the leg length, the PVF and stiffness were both lower in the obese group than in control subjects. Conclusion: In the context of performance, we concluded that increased dimensionless leg stiffness during the gait cycle is associated with increased velocity of COM, PVF, and the change in leg lengths (%).

• Korean Journal of Applied Biomechanics
• /
• v.22 no.3
• /
• pp.365-371
• /
• 2012

We aimed to analyze the muscle activity of adolescent patients with idiopathic scoliosis during gait and develop the wearing of musculo-skeletal functional garment by applying the principle of sports taping based on the result of the analysis. We selected 20 male students between the ages of 13 and 18 and divided them into 2 groups: one group consisted of 10 patients with idiopathic scoliosis <20 degrees of Cobb's Angle: the other group had 10 normal students. Using, we measured and analyzed the muscle activity of 8 different regions: left and right latissimus dorsi, left and right thoracolumbar fascia, left and right gluteus medius, and left and right biceps femoris during gait. Our results can be summarized as follows: Firstly, in patients with idiopathic scoliosis, the gait showed a significantly low activity of the right latissimus dorsi muscle when the left foot was supported on the ground(p<.05). Secondly, in the overall gait cycle, the patients showed a higher activity of the right thoracolumbar fascia and right gluteus medius than that seen in the normal students: however, this difference was not statistically significant. Thirdly, by applying sports taping on the bisis of the results, this study developed the wearing of musculo-skeletal functional garment that could maximize the stimuli of the right latissimus dorsi and alleviate muscle contraction of the right thoracolumbar fascia and right gluteus medius, while expanding the spinal line upward and downward, by focusing on the difference between left and right muscular strength of the muscle activity of the bright latissimus dorsi. Overall, we expect that by wearing of musculo-skeletal functional garment, the muscular functions in adolescents with idiopathic scoliosis.

• Journal of the Korea Safety Management & Science
• /
• v.11 no.2
• /
• pp.103-110
• /
• 2009

The purpose of this study is to suggest a proper tread of stairs using kinematic factors and moments of the lower-limb joints in the stair decent with the 3 different treads with boimechanical method in ergonomics. 9 subjects (body masses; $59.41{\pm}7.49$, $64.03{\pm}6.65$, $67.26:{\pm}7.58$, heights; $160.50{\pm}6.35$ ages; $31.22{\pm}2.99$; parity; $1.67{\pm}0.71$) participated in three experiments that were divided by physiological symptoms (the early (0-15 weeks), middle (16-27 weeks) and last (18-39 weeks). and they walked at self-selected pace on 4 staircases 3 trials. As extending the pregnancy period, cadence was shorter but cycle time were longer more and more. As extending treads of stair decent during pregnancy, speed, stride lengths and cycle time were increased. As extending the treads of stair decent, hip and ankle moments increased but knee moments decreased in sagittal plane. There were increasing or decreasing of moments by means of treads. These changes may account for relation between the treads of stair and moments in pregnant women. The main changes of pregnant women were joint moments and kinematic factors during pregnancy period because pregnancy makes them physical changes. It is possible that joints have connection with compensation each other to maximize stability and to control gait motion. In conclusion, we suggest that the tread of stair is longer than 26cm tread. and exercise programs to improve muscle activity were necessary where joint moments were small.

• Korean Journal of Applied Biomechanics
• /
• v.20 no.4
• /
• pp.387-393
• /
• 2010

The purpose of this study was to compare pregnant women's gait parameters and mechanical energies caused by changes in hormone levels and anatomical features such as body mass, body-mass distribution, joint laxity, and musculo-tendinous strength from pregnancy to postpartum. Ten subjects (height: $161{\pm}6.5cm$, mass: $62.7{\pm}10.4\;kg$, $66.4{\pm}9.3\;kg$, $68.4{\pm}7.7\;kg$, $57.2{\pm}7.7\;kg$) participated in the four times experiments (the first, middle, last term and after birth) and walked ten trials at a self-selected pace without shoes. The gait motions were captured with Qualisys system and gait parameters were calculated with Visual-3D. Pregnant women's gait velocities were decreased during the pregnancy periods, but increased after birth. Stride width and cycle time were increased during pregnancy, but decreased after birth. Thigh energy (77.4%) was greater than shank energy (19.06%) or feet (3.54%) about total energy of the lower limbs. Their feet (Left R2=0.881, Right R2=0.852) and shank (Left R2=0.318, Right R2=0.226) energies were significantly increased (positive correlation), but double limb stance time (DLST, R2=0.679) and body total energy (R2=0.138) were decreased (negative correlation) for their velocities. These differences suggest that thigh segment may be a dominant segment among lower limbs, and have something to do with gait velocities. Further studies should investigate joint power and joint work to find energy dissipation or absorption from pregnancy period to postpartum.

• Proceedings of the KOSOMBE Conference
• /
• v.1997 no.05
• /
• pp.253-256
• /
• 1997

KESF-1 foot conceptually provides storage of potential energy and is converted to kinetic energy throughout the weight - bearing phase of the gait cycle. This stored energy is progressively released as the foot continues through the toe-off phase to rebound and propel the body forward. A weight deflects the keel through a predetermined range, then the keel "springs back" as weight is removed. Foot designs criteria were selected to guide development beyond the proof-of concept composite material keels; 1) store and return energy (1-3/4 " metatarsal deflection at 435 pounds vertical load), 2) natural feel and stability; 3) useful life of 3-years: 4) lightweight; 5) reduced production costs. The purpose of this study is developed the comfortable stable foot that fitted with Korean lifestyle and road condition. The results produced the realistic cosmetic foot cover with polyurethane form and the keel composed with composite materials of both glass fiber and carbon fiber.

• Journal of Biomedical Engineering Research
• /
• v.28 no.1
• /
• pp.108-116
• /
• 2007

Recently, it has been reported that the posterior stabilized implant, which is clinically used for the total knee replacement (TKR), may have failure risk such as wear or fracture by the contact pressure and stress on the tibial post. The purpose of this study is to investigate the influence of the mal alignment of the posterior stabilized implant on the tibial post by estimating the distributions of contact pressure and von-Mises stress on a tibial post and to analyze the failure risk of the tibial post. Finite element models of a knee joint and an implant were developed from 1mm slices of CT images and 3D CAD software, respectively. The contact pressure and the von-Mises stress applying on the implant were analyzed by the finite element analysis in the neutral alignment as well as the 8 malalignment cases (3 and 5 degrees of valgus and varus angulations, and 2 and 4 degrees of anterior and posterior tilts). Loading condition at the 40% of one whole gait cycle such as 2000N of compressive load, 25N of anterior-posterior load, and 6.5Nm of torque was applied to the TKR models. Both the maximum contact pressure and the maximum von-Mises stress were concentrated on the anterior-medial region of the tibial post regardless of the malalignment, and their magnitudes increased as the degree of the malalignment increased. From present result, it is shown that the malalignment of the implant can influence on the failure risk of the tibial post.