• Journal of the Korean Society of Physical Medicine
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• v.8 no.4
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• pp.549-558
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• 2013

PURPOSE: This study is designed as a retrospective study, and identified the clinical usability of Sit to Stand (STS) test for predicting of fall incidence in stroke patients who experienced a fall within 1 year. METHODS: Between July 2011 and November 2012, 69 inpatients with stroke in K rehabilitation hospital were participated under voluntarily signing the informed consent form. STS test and 10m walk test (10MWT) were used to assess the muscle strength of lower-extremity and walking velocity, respectively. Also, we tested dynamic balance and motor function of lower-extremity in affected-side using with the Berg balance scale (BBS) and the Fugl-Meyer assessment of lower extremity (FM-L/E). METHODS: There were significant differences between subjects with fall-experienced group and without subjects without fall-experienced group in STS test, 10MWT, BBS scores and FM-L/E. STS test significantly showed a negative correlation between 10MWT (r=-.657), BBS (r=-.512), and FM-L/E (r=-.563). And, 10MWT have a influence on the performance of STS test (the capacity of explanation = 20%). The cut-off value of STS performance predicting falls experience is ${\geq}14.36$ seconds (sensitivity=76%; specificity=79%, area under curve=.785). According to logistic regression analysis of falls experience, subjects ${\geq}14.36$ s showed that 4.164 times (odd ratio) increased in falls than subjects < 14.36 s in STS test. CONCLUSION: This study demonstrated that STS test may be a useful tool predicting and measuring falls in patients with stroke. Further study will be needed to elucidate the kinematic analysis of STS test and the relationship between physical activity level and falls in stroke patients.

• PNF and Movement
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• v.17 no.2
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• pp.215-222
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• 2019

Purpose: The objective of this study was to investigate whether augmented low-dye taping treatment, which consists of low-dye, reverse-six, and calcaneal-sling taping, is effective in alleviating the collapse of the medial longitudinal arch, which is used for physical balancing during one leg standing. Methods: The subjects comprised 27 students in their 20s whose navicular bone height was lowered by 10 mm or more when evaluated using the navicular drop test. Those with interference factors like deformities, fractures, or traumas were excluded. Frequency-division multiplexing was used to measure one leg standing, and the method to avoir the average each time after 3 times of measurement was applied. Results: Significant differences in the center of pressure (COP) path length, COP average velocity, and forefoot force were observed during left leg standing (p<0.05), but for right leg standing, only changes in forefoot force were noted. Conclusion: Based on the changes to the non-dominant leg in terms of COP path length, COP average velocity, and forefoot force, the immediate effect of augmented low-dye taping, which combines three types of anti-pronation taping, on one leg standing balance in people with flat feet was confirmed.

• Physical Therapy Rehabilitation Science
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• v.7 no.3
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• pp.139-145
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• 2018

Objective: Older persons with diabetes mellitus (DM) are particularly more likely to have fallen in the previous year than those without DM. The purpose of this study was to investigate the relationship between the risk of falls and type 2 DM in older adults who are 65 years of age or above. Design: A systematic review. Methods: PubMed and other two databases were searched up to August 2, 2018. Observational and cohort studies evaluating fall risk in people who are 65 years of age or above with DM were included. This review extracted the following information from each study selected: first author's surname, year of publication, country, average follow-up period, sex, age at enrollment, study population, measurement variables, relative risk, 95% confidence intervals and controlled variables. Results: This review involved nine cohort studies with 3,765 older adults with DM and 12,989 older adults without DM. Six studies compared with or without DM and two studies compared fallers with non-fallers with DM. Risk factors for falls included impaired cognitive function, diabetes-related complications (peripheral nerve dysfunction, visual impairment), and physical function (balance, gait velocity, muscle strength, and severity of physical activities). Conclusions: People who are 65 years of age or above with DM have increased risk of falling caused by impaired cognitive function, peripheral nerve dysfunction, visual impairment, and physical function in community-dwellers. For adults who are 65 years of age or older with DM, research fields and clinical settings should consider therapeutic approaches to improve these risk factors for falls.

• Journal of the Korean Society for Precision Engineering
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• v.17 no.12
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• pp.169-175
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• 2000

Stable and comfortable walking supports, which can reduce the body weight load partially, are needed for the recovering patients from neurologic disease and orthopedic procedures. In this paper, the development of a manipulator of rehabilitation robot for the patients with walking disabilities are studied. A force controller using pneumatic actuators is designed and implemented to the human friendly rehabilitation robot considering the safety of patients, reliability of the system, effectiveness of the unloading control and economic maintenance of the system. The mechanism of the unloading manipulator is devised to improve the sensibility for the movement of the patients such as direction and velocity. For the unloading force control, fuzzy control algorithm is adopted to reduce the partial body weight and suppress the unwanted fluctuation of the body weight load to the weak legs due to the unnatural working of the patients with walking disabilities. The effectiveness of the force control is experimentally demonstrated.

• Journal of Institute of Control, Robotics and Systems
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• v.11 no.1
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• pp.58-66
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• 2005

Usual human gait can be modeled as continual impact phenomenon that happens due to the topological change of the kinematic structure of the two feet. The human being adapts his own control algorithm to minimize the ill effect due to the collision with the environment. In order to operate a Humanoid robot like the human being, it is necessary to understand the physics of the impact and to derive an analytical model of the impact. In this paper, specially, we focus on impact analysis of the kicking motion in playing soccer. At the instant of impact, the external impulse exerted on the ball by the foot is an important property. Initially, we introduce the complete external impulse model of the lower-extremity of the human body and analyze the external impulses for several kicking postures of the lower-extremity. Secondly, a trajectory-planning algorithm of a ball, in which the initial velocity and the launch angle of the ball are calculated for a desired trajectory of the ball, will be introduced. The aerodynamic effect such as drag force and lift force is also considered. We carry out numerical simulation and experimentation to verify the effectiveness of the proposed analytical methodology.

• Journal of the Korean Society for Precision Engineering
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• v.23 no.4 s.181
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• pp.75-82
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• 2006

In this paper, we propose an optimal trajectory for biped robots to move up-and-down stairs using a genetic algorithm and a computed-torque control for biped robots to be dynamically stable. First, a Real-Coded Genetic Algorithm (RCGA) which of operators are composed of reproduction, crossover and mutation is used to minimize the total energy. Constraints are divided into equalities and inequalities: Equality constraints consist of a position condition at the start and end of a step period and repeatability conditions related to each joint angle and angular velocity. Inequality constraints include collision avoidance conditions of a swing leg at the face and edge of a stair, knee joint conditions with respect to the avoidance of the kinematic singularity, and the zero moment point condition with respect to the stability into the going direction. In order to approximate a gait, each joint angle trajectory is defined as a 4-th order polynomial of which coefficients are chromosomes. The effectiveness of the proposed optimal trajectory is shown in computer simulations with a 6-dof biped robot that consists of seven links in the sagittal plane. The trajectory is more efficient than that generated by the modified GCIPM. And various trajectories generated by the proposed GA method are analyzed in a viewpoint of the consumption energy: walking on even ground, ascending stairs, and descending stairs.

• Journal of Mechanical Science and Technology
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• v.20 no.5
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• pp.612-620
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• 2006

This paper proposes an optimal trajectory generation method for biped robots for walking up-and-down stairs using a Real-Coded Genetic Algorithm (RCGA). The RCGA is most effective in minimizing the total consumption energy of a multi-dof biped robot. Each joint angle trajectory is defined as a 4-th order polynomial of which the coefficients are chromosomes or design variables to approximate the walking gait. Constraints are divided into equalities and inequalities. First, equality constraints consist of initial conditions and repeatability conditions with respect to each joint angle and angular velocity at the start and end of a stride period. Next, inequality constraints include collision prevention conditions of a swing leg, singular prevention conditions, and stability conditions. The effectiveness of the proposed optimal trajectory is shown in computer simulations with a 6-dof biped robot model that consists of seven links in the sagittal plane. The optimal trajectory is more efficient than that generated by the Modified Gravity-Compensated Inverted Pendulum Mode (MGCIPM). And various trajectories generated by the proposed GA method are analyzed from the viewpoint of the consumption energy: walking on even ground, ascending stairs, and descending stairs.

• Journal of Biomedical Engineering Research
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• v.30 no.3
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• pp.226-232
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• 2009

In this study, treadmill walking and overground walking were compared at the same condition based on kinematics and energy expenditures(EE). In addition, we compared the actual energy expenditure and calculated EE by treadmill. The kinematics of treadmill and overground walking were very similar. The values at each joint were significantly different(P<0.05), but magnitude of the difference was generally less than 4$^{\circ}$. In the EE using cardiopulmonary exercise, EE of treadmill walking was significantly greater when measured on the overground. It seemed to be the increased stress during the gait by the continuous movement of the belt. As the velocity increased, there was significant difference between actual EE and calculated EE by treadmill due to EE curve increasing exponentially. Therefore the further study would be required to find the correlation of the two methods and calibrate the values from them.

• Journal of Institute of Control, Robotics and Systems
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• v.17 no.10
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• pp.1029-1036
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• 2011

An energy-efficient reference walking trajectory generation algorithm is suggested utilizing allowable ZMP (Zero-Moment-Point) region, which maxmizes the energy efficiency for cyclic gaits, based on three-dimensional LIPM (Linear Inverted Pendulum Model) for biped robots. As observed in natural human walking, variable ZMP manipulation is suggested, in which ZMP moves within the allowable region to reduce the joint stress (i.e., rapid acceleration and deceleration of body), and hence to reduce the consumed energy. In addition, opimization of footstep planning is conducted to decide the optimal step-length and body height for a given forward mean velocity to minimize a suitable energy performance - amount of energy required to carry a unit weight a unit distance. In this planning, in order to ensure physically realizable walking trajectory, we also considered geometrical constraints, ZMP stability condition, friction constraint, and yawing moment constraint. Simulations are performed with a 12-DOF 3D biped robot model to verify the effectiveness of the proposed method.

• The Journal of Korea Robotics Society
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• v.14 no.4
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• pp.270-277
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• 2019

Inspired by small insects, which perform rapid and stable locomotion based on body softness and tripod gait, various milli-scale six-legged crawling robots were developed to move rapidly in harsh environment. In particular, cockroach's leg compliance was resembled to enhance the locomotion performance of the crawling robots. In this paper, we investigated the effects of changing leg compliance for the locomotion performance of the small light weight legged crawling robot under various payload condition. First, we developed robust milli-scale six-leg crawling robot which actuated by one motor and fabricated in SCM method with light and soft material. Using this robot platform, we measured the running velocity of the robot depending on the leg stiffness and payload. In result, there was optimal range of the leg stiffness enhancing the locomotion ability at each payload condition in the experiment. It suggests that the performance of the crawling robot can be improved by adjusting stiffness of the legs in given payload condition.