• Korean Journal of Applied Biomechanics
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• v.29 no.2
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• pp.105-112
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• 2019

Objective: The main purpose of this study was to investigate the effects of wearing an ankle weight belt while performing gait in water by focusing on the effect of using ankle weights have on the gait kinematics and the muscle activities for developing optimum training strategies. Method: A total of 10 healthy male university students were recruited for the study. Each participant was instructed to perform 3 gait conditions; normal walking over ground, walking in water chest height, and walking in water chest height while using ankle weights. All walking conditions were set at control speed of $4km/h{\pm}0.05km/h$. The depth of the swimming pool was at 1.3 m, approximately chest height. The motion capture data was recorded using 6 digital cameras and the EMG was recorded using waterproof Mini Wave. From the motion capture data, the following variables were calculated for analysis; double and single support phase (s), swing phase (s), step length (%height), step rate (m/s), ankle, knee, and hip joint angles ($^{\circ}$). From the electromyography the %RVC of the lower limb muscles medial gastrocnemius, rectus femoris, erector spinae, semitendinosus, tibialis anterior, vastus lateralis oblique was calculated. Results: The results show significant differences between the gait time, and step length between the right and left leg. Additionally, the joint angular velocities and gait velocity were significantly affected by the water resistance. As expected, the use of the ankle weights increased all of the lower leg maximum muscle activities except for the lower back muscle. Conclusion: In conclusion, the ankle weights can be shown to stimulate more muscle activity during walking in chest height water and therefore, may be useful for rehabilitation purposes.

• 제어로봇시스템학회:학술대회논문집
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• 2003.10a
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• pp.645-650
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• 2003

Legged robots can avoid an obstacle by crawling-over or striding, according to the obstacle’s nature and the current state of the robot. Thus, it can be observed that the mobility efficiency to reach a destination is improved by such action. Moreover, if robots have many legs like 4-legged or 6-legged types, then the robot movement range is affected by the order of swing leg. In this paper, the avoidance action of a quadruped robot is generated by a neural network (NN) whose inputs are information on the position of the destination, the obstacle configuration and the robot's self-state. To realize a free gait in static walking, the order of swing leg is determined using an another NN whose inputs are the amount of movements and the robot’s self-state. The design parameter of the latter NN is adjusted by using genetic algorithm (GA).

• Proceedings of the IEEK Conference
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• 2003.07c
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• pp.2887-2890
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• 2003

This paper describes the possibility of analyzing gait pattern from the variation of the lower leg electrical impedance. This impedance is measured by the four-electrode method. Two current electrodes are applied to the thigh, knee, and foot, and two potential electrodes are applied to the lateral, medial, and posterior position of lower leg. The correlation coefficients of the joint angle and the impedance change from human leg movement was obtained using electrogoniometer and 4ch impedance measurement system developed in this study. We found the optimal electrode position for ankle, knee and hipjoint movements based on high correlation coefficient, least interference, and maximum magnitude of impedance change. The correlation coefficients of the ankle, knee, and the hip movements -0.87, 0.957 and 0.80. respectively. From such features of the lower leg impedance, it has been made clear that different movement patterns exhibit different impedance patterns and impedance level. This system showed possibility that lower leg movement could be easily measured by impedance measurement system with a few skin-electrodes.

• 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.

• Journal of the Korean Society of Physical Medicine
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• v.15 no.4
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• pp.37-45
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• 2020

PURPOSE: The purpose of this study was to identify the effects of neck stabilization exercise combined with trunk stabilization exercise on balance and gait function in patients with chronic stroke. METHODS: Twenty-two chronic stroke patients were included in this study. The experimental group subjects (n = 11) performed neck stabilization (15 min) and trunk stabilization (15 min) exercises, while the control group subjects (n = 11) performed trunk stabilization exercise only for 30 min. Before and after the intervention, the subjects underwent static balance and gait testing. RESULTS: The 95% confidence ellipse area, center of pressure (COP) path length, and COP average velocity were significantly lower in both groups after the intervention compared to before intervention (p < .05). The average stance force on the affected side increased significantly in both groups after the intervention (p < .05). The changes in the static balance variables were larger in the experimental group than in the control group. The cadence, gait velocity, and single leg support increased significantly in both groups after intervention (p < .05). The changes in the gait variables were larger in the experimental group than in the control group. CONCLUSION: Trunk stabilization is a beneficial intervention, but the combination of neck stabilization with trunk stabilization is a more effective method to increase the gait and static balance in chronic stroke patients.

• Journal of the Korean Society of Physical Medicine
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• v.12 no.2
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• pp.53-57
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• 2017

PURPOSE: The purpose of study was to clear up the environmental risk factor that can be easily occurred unstability of hip during gait and one leg standing at various ramp angle. METHODS: Twenties healthy males of 69 subjects is participated in this study. Participants was measured activation on gluteus medius muscle during both conditions (walk across the ramp and one leg stand in the transverse direction) of seven different angle. The measured data were analyzed using one-way ANOVA to investigate the effect of muscle activation on the each condition. The statistical analyses were performed using SPSS ver. 18.0 and p-value less than .05 were considered significant for all cases. A post-hoc test was performed by Bonferoni method. RESULTS: The study showed that more muscle activities on gluteus medius is increased by increasing the ramp angle. Post-hoc analysis demonstrated that the peak and mean of muscle activity increased significantly with a ramp angle of $15^{\circ}$ and $25^{\circ}$ during gait and one-leg stand. CONCLUSION: According to the study results, impaired balance can be easily occurred when cross walk and one-leg stand on a ramp from higher than $15^{\circ}$, and highest risk was angle of $25^{\circ}$ or more. As a people with gluteus medius muscle weakness walks a ramp, the ramp angle has a cross relationship with the impaired balance. If people with gluteus medius weakness walk on the more than $10^{\circ}$ of ramp angle, they will need a lot of attention for prevent impaired balance.

• Journal of The Korean Society of Integrative Medicine
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• v.9 no.4
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• pp.85-89
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• 2021

Background : Klippel-Trenaunay-Weber syndrome (KTS) is a rare congenital medical condition characterized by complex vascular malformation. KTS consists of a classic triad of capillary malformation (hemangioma), venous malformations and bone or soft tissue hypertrophy causing limb asymmetry. The aim of this report is to describe management for gait disturbance and foot pain in a Patient with KTS using custom-made total contact insole. Case presentation : A 32-year-old man with KTS presented with a 3-year history of gait disturbance on hard surface due to right first toe pain and Achilles tendon tightness. The patient had soft tissue hypertrophy, varicose veins and port-wine stains over the right lower limb associated with KTS. True leg length discrepancy was 2 cm. We prescribed custom-made total contact insole to protect his deformed foot and correct leg length discrepancy. The insole of right side included wedge shaped heel lift and the insole of left side included full length lift to add extra support on unaffected side. Also, we provided compression stocking and physiotherapy including manual lymphatic drainage for lymphedema and stretching exercise for tightness in right lower extremity. At 3 years follow-up, postural alignment including pelvic obliquity was improved using a custom-made total contact insole. The degree of scoliosis and foot pain were also reduced. Conclusion : An individualized and multidisciplinary approach is essential regarding the complexity of comorbidities in patients with KTS. For patients with KTS, orthotic management should be considered to prevent and correct deformities related to KTS. Active orthotic management, compression stocking and physiotherapy can enhance the quality of life and function in patients.

• 제어로봇시스템학회:학술대회논문집
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• 2003.10a
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• pp.203-208
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• 2003

In this paper, gait generation algorithm based on Linear Inverted Pendulum Mode is extended considering that the terrain is uncertain and flexible. Deformation of the soft terrain by the weight of the biped robot is taken into account to design the desired motion of the swing leg. Landing time disagreement caused by dynamics of the robot is also considered and a method to adjust gait is proposed. Results of numerical simulation show the effectiveness of the proposed method.

• Journal of the Korean Society for Precision Engineering
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• v.21 no.7
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• pp.115-123
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• 2004

This paper deals with the gait optimization of via points on biped robot. ZMP(Zero Moment point) is the most important index in a biped robot's dynamic walking stability. To stable walking of a biped robot, leg's trajectory and a desired ZMP trajectory is required, balancing motion is solved by FDM(Finite Difference Method). In this paper, optimal index is defined to dynamically stable walking of a biped robot, and genetic algorithm is applied to optimize gait trajectory and balancing motion of a biped robot. By genetic algorithm, the index of walking parameter is efficiently optimized, and dynamic walking stability is verified by ZMP verification equation. Genetic algorithm is only applied to balancing motion, and is totally applied to whole trajectory. All of the suggested motions of biped robot are investigated by simulations and verified through the real implementation.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.58 no.11
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• pp.2266-2268
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• 2009

In this paper, a simple method of angle velocity estimation is presented for a passive dynamic biped robot. The estimation problem is not an easy task because its dynamic model is a hybrid system involved with an impact condition. Instead of designing a complex observer for hybrid systems we simply utilize the impact condition to reset the initial condition of the high-pass filter when the non-support leg hits the slope. The approach has been verified by simulation results.