• Proceedings of the KIEE Conference
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• 2006.10c
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• pp.542-544
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• 2006

This paper aims to provide a way to improve dynamic stability of biped robots against undesirable disturbances and in a slope. By using an angular velocity sensor and an acceleration sensor on its waist, we can make a medium-sized biped robot walk stably in a slope against impulsive disturbances. In addition, it is possible for the robot to walk stably in an unknown slope. The measured signals from the sensor are used for compensating the reference angles of ankle, knee, and pelvis joints. Some experiments show that the stability of the robot is much enhanced by using cheat sensors and a simple algorithm. This work helps bided robots walk more stably in real environments.

• Proceedings of the KIEE Conference
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• 2006.04a
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• pp.309-311
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• 2006

This paper aims to provide a way to improve dynamic stability of biped robots against undesirable disturbances. By using an angular velocity sensor on its shoulder, we can make a medium-sized biped robot walk stably against an impulsive disturbance. The measured signal from the sensor in used for compensating the reference angles of ankle, knee, and pelvis joints. An experiment shows that the stability of the robot is much enhanced by using a cheap sensor and simple algorithm. This kind of research helps biped robots walk more stably in real environments.

• 제어로봇시스템학회:학술대회논문집
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• 2000.10a
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• pp.43-43
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• 2000

In this paper, we introduce a case study of developing a miniature humanoid robot that has 16 degrees of freedom and is able to perform statically stable walking. The developed humanoid robot is 37cm tall and weighs 1,200g. RC servo motors are used as actuators. The robot can walk forward and turn to any direction on even surface. It equipped with a small digital camera, so it can transmit vision data to a remote host computer via wireless modem. The robot can be operated in two modes; One is a remote-controlled mode, in which the robot behaves according to the command given by a human operator through the user-interface program running on a remote host computer, the other is a stand-alone mode, in which the robot behaves autonomously according to the pre-programmed strategy. The user-interface program also contains a robot graphic simulator that is used to produce and verify the robot's gait motion. In our walking algorithm, the ankle joint is mainly used lot balancing the robot. The experimental results shows that the developed robot can perform statically stable walking on even surface.

• Physical Therapy Rehabilitation Science
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• v.11 no.4
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• pp.579-584
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• 2022

Objective: To identify the effect of unstable surface kettlebell exercises on muscle activity and balance in middle and high school baseball players. Design: Randomized controlled trial. Methods: The participants were 29 middle and high school baseball players (Unstable surface kettlebell exercises group, USKE: 15; Stable surface kettlebell exercise group, SSKE: 14). The players in the USKE group performed kettlebell exercises for 60 mins on a stable surface thrice a week for 6 weeks, and the return rack was solidified on a stable surface in the same way as the experimental group. Before and after the experiment, the participant's muscle activity of the tibialis anterior and soleus was measured. In addition, the participant's balance was evaluated by measuring the distance moved from the foot's center of pressure (COP). The paired t-test was used to compare groups before and after the experiment. The independent t-test was conducted to assess differences in the degree of change between the two groups before and after the experiment. Results: Compared to the SSKE group, the USKE group showed significant differences in the muscle activity of the tibialis anterior and soleus and the balance with the eyes open and closed. Conclusions: The players in the USKE group showed a significant difference in muscle activity and balance than in those in the SSKE group. Thus, effectively including an unstable surface in the kettlebell exercise program will help improve physical function in athletes and people with musculoskeletal disorders.

• Journal of Korean Foot and Ankle Society
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• v.12 no.2
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• pp.180-184
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• 2008

Purpose: To evaluate the result of percutaneous fixation with cannulated screws and Ilizarov external fixator in triplane fracture of the distal tibial epiphysis in children. Materials and Methods: Between May 2004 and December 2007, 14 cases with triplane fractures were treated by percutaneous fixation with cannulated screws and Ilizarov external fixator after underwent CT imaging to assess the fracture pattern, articular disruption and to plan further management. Mean age and follow-up period were 14.1 years old and 15 months respectively. Results: There were satisfactory results in all 14 cases that had excellent reduction and stable fixation. All cases regained full range of movement within 6 weeks. Conclusion: We obtained satisfactory result after percutaneous fixation with cannulated screws and Ilizarov external fixator in triplane fractures of the distal tibial epiphysis in children.

• Journal of Institute of Control, Robotics and Systems
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• v.13 no.9
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• pp.843-850
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• 2007

This paper proposes a somatosensory stimulation system for the improvement of postural stability using vibration as somatosensory stimulation. This system consists of vibratory stimulation and postural response measurement. To evaluate this system, the center of pressure(COP) was closely observed in turn with simultaneous or separate mechanical vibratory stimulations to flexor ankle muscles (tibialis anterior, triceps surae) and two plantar zones on both feet while standing on a stable and an unstable support. The simultaneous vibratory stimulations cleared influenced postural stability and the effects of vibrations were higher with the unstable support. In separate vibratory stimulations, the extent of the COP sway reduced when the direction of the vibratory stimulations and that of the inclination of body coincided for flexor ankle muscle stimulations. In the contrary, the extent of the COP sway increased when the direction of the stimulations and that of body inclination coincided for plantar zone stimulations. These results can be useful for the development of rehabilitation systems that utilizes somatosensory inputs for postural balance.

• Journal of the Korean Society of Physical Medicine
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• v.18 no.3
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• pp.65-72
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• 2023

PURPOSE: This study assessed the influence of bilateral coordination exercises on unstable support surfaces on leg muscle activation and balance in stroke patients. METHODS: Two groups were recruited for comparison: an experimental group of 10 individuals who performed bilateral coordination exercises on unstable surfaces and a control group of 10 individuals who performed the same exercises on stable surfaces. All participants were assigned randomly. Pre-tests were conducted to measure the leg muscle activation and balance levels of the participants prior to the experiment. The intervention was comprised of three 30-minute weekly sessions for four weeks, followed by a post-test after the four-week period. RESULTS: Significant differences were identified within the experimental group in relation to all muscles (p < .01) and balance (p < .05). Within the control group, significant differences were identified in relation to the rectus femoris muscle, biceps femoris muscle, and balance (p < .05). Significant differences between the two groups were only observed in relation to the tibialis anterior and soleus muscles (p < .05). CONCLUSION: Only the tibialis anterior and soleus muscles showed significant differences between the two groups. This effectiveness may be attributed to using an ankle strategy to maintain body balance during exercise on unstable surfaces.

• Journal of Korean Foot and Ankle Society
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• v.16 no.4
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• pp.235-240
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• 2012

Purpose: The aim of this study was to evaluate the radiographic and clinical results of short scarf osteotomy that has minimized longitudinal cut for moderate hallux valgus. Materials and Methods: Total 12 patients (12 feet) were reviewed by medical records and radiographs. All patients were female and the mean age at the time of operation was 41.5 years. The mean followup time was 21.2 months. We modified original scarf osteotomy by shortening the longitudinal cut to 15~20 mm in length. Additionally, Akin osteotomy of the first proximal phalanx was done in 7 feet and Weil osteotomy of the second metatarsal was done in 4 feet. First-second intermetatarsal and hallux valgus angles were analyzed radiographically before and after the operation. And the clinical result was assessed by AOFAS (American Orthopaedic Foot and Ankle Society) hallux score. Results: First-second intermetatarsal and hallux valgus angles were reduced from the mean preoperative values of $14.6^{\circ}$ and $32.8^{\circ}$ to $6.5^{\circ}$ and $11.2^{\circ}$, respectively. The mean AOFAS hallux score was increased from 52.4 points preoperatively to 88.2 points at followup. Three complications were found: metatarsal fracture during the operation, painful scar around second metatarsal head after Weil osteotomy and postoperative neuralgia. There was no transfer metatarsalgia or recurrence of hallux valgus during followup. Conclusion: Short scarf osteotomy would be an effective surgical procedure for moderate hallux valgus with the benefits of minimized soft tissue dissection and stable fixation.

• Journal of Korean Foot and Ankle Society
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• v.8 no.2
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• pp.126-130
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• 2004

Purpose: In this study, we tried to develop the technique of osteotomy for hallux valgus. The new modified technique of osteotomy was accomplished with even more greater stability, accurate correction of the deformity and more effective than 'chevron' osteotomy in terms of correction of the deformity. Materials and Methods: Between March 1998 and December 2001, 55 cases of new modified osteotomy for hallux valgus were performed for 39 patients, 16 of whom underwent operation of both feet. Operations were made for 34 women and 5 men whose average age was 46 years old (range, $20{\sim}71$ years). Average follow up period was three years (range, $2{\sim}5$ years), and during the follow up, the patients underwent physical examination and assessment with use of the American Orthpaedic Foot and Ankle Society's hallux-metatarso-phalangealinterphalangeal scale and standard foot radiographic measurements. Results: 37 patients (53 cases) out of 39 patients (55 cases) had no pain, good cosmesis, and all of the patients were satisfied with the results of the operation. Two had occasional mild discomfort. The average score according to the hallux-metatarso-phallangeal-interphalangeal scale was 93.2 points (range, $78{\sim}100$ points). The average preoperative intermetatarsal angle was $14.4^{\circ}$, which was decreased to $7.9^{\circ}$ after the osteotomy with an average correction of $6.5^{\circ}$ and The average preoperative hallux valgus angle was $34.1^{\circ}$, which was decreased to $11.1^{\circ}$ after the osteotomy with an average correction of $23^{\circ}$. This new modified technique would prevent the angulation or shortening at the osteotomy site and it was also even more stable at osteotomy site, and could do even more effective and accurate correction of the deformity than conventional Chevron osteotomy. Conclusion: New modified chevron osteotomy for the treatment of symptomatic hallux valgus was done in 55 cases, and the results were satisfactory in all cases. This method was more stable at the osteotomy site than conventional Chevron osteotomy and was also possible to do more accurate and more effective correction of the deformity. It was also easy to control the distal fragment of first metatarsal bone.

• Journal of Institute of Control, Robotics and Systems
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• v.7 no.5
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• pp.420-426
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• 2001

In this paper, we introduce a case study of developing a miniature humanoid robot that has 16 degrees of freedom and is able to perform statically stable walking. The developed humanoid robot is 37cm tall and weighs 1,200g. RC servo motors are used as actuators. The robot can walk forward and turn to any direction on an even surface. It equipped with a small digital camera, so it can transmit vision data to a remote host computer via wireless modem. The robot can be operated in two modes: One is a remote-controlled mode, in which the robot behaves according to the command given by a human operator through the user-interface program running on a remote host computer, the other is a stand-alone mode, in which the robot behaves autonomously according the pre-programmed strategy. The user-interface program also contains a robot graphic simulator that is used to produce and verify the robot\`s gait motion. In our walking algorithm, the ankle joint is mainly used for balancing the robot. The experimental results shows that the developed robot can perform statically stable walking on an even surface.