• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.18 no.5
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• pp.521-528
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• 2009

In these days, biomimetic apprioach in the design and control of robotic system has drawn much attention. The human-being and mammals possess their own feet. Using the mobility of their feet, they are able to walk in various environments such as plain land, desert, swamp, and so on. Previously developed biped robots and four-legged robots did not employ such adaptable foot. In this work, a biomimetic foot mechanism is investigated through analysis of the foot structure of the human-being. This foot mechanism consists of a toe, an ankle, a heel, and some springs replacing the foot muscles and tendons. Using five toes and springs, this foot can adapt to various environments. A mathematical modeling for this foot mechanism was performed and its characteristics were observed through numerical simulation.

• Journal of the Korean Institute of Intelligent Systems
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• v.22 no.3
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• pp.347-352
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• 2012

This paper presents a robotic foot mechanism based on truss structure for walking robots and analyzes its effectiveness for compliant walking. The specified foot mechanism has been modeled by observing the structure and behavior of human foot. The frame of bone used in the human foot is considered as a truss, and the ligaments of the human foot are represented as a simple stiffness element. So such a robotic foot has an advantage to moderate the impact of foot when a walking robot takes a step. As a result, it is practically expected that the proposed robotic foot mechanism can contribute to reduce the physical fatigue of walking robots.

• Journal of the Korean Institute of Intelligent Systems
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• v.23 no.1
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• pp.12-17
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• 2013

This paper presents a model of bipedal leg mechanism with a compliant foot, and the contact repulsion of the foot for a typical walking pattern and its influence on the knee and hip joints of the leg will be analyzed. This analysis is useful for us to figure out the physical impact of the foot when a walking robot takes a step. Also it can be applied to determine the joint specification of the leg mechanism. As a result, it is shown that the compliance characteristics of a robotic foot can contribute to alleviate the joint torques of the leg affected by the contact repulsion of the foot.

• The Journal of Korea Robotics Society
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• v.12 no.2
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• pp.161-172
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• 2017

Foot mechanisms play the role of interface between the main body of robotic systems and the ground. Biomimetic design of the foot mechanism is proposed in the paper. Specifically, multi-chained and multiple contact characteristics of general foot mechanisms are analyzed and their advantages are highlighted in terms of impulse. Using Newton-Euler based closed-form external and internal impulse models, characteristics of multiple contact cases are investigated through landing simulation of an articulated leg model with three kinds of foot. It is shown that in comparison to single chain and less articulated linkage system, multi-chain and articulated linkage system has superior characteristic in terms of impulse absorption as well as stability after collision. The effectiveness of the simulation result is verified through comparison to the simulation result of a commercialized software.

• Structural Engineering and Mechanics
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• v.66 no.1
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• pp.1-14
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• 2018

Column is usually floating on the stone base directly with or without positioning tenon in traditional Chinese timber structure. Vertical load originated by the heavy upper structure would induce large friction force and compression force between interfaces of column foot and stone base. This study focused on the mechanical behaviors of column foot joint with consideration of the influence of vertical load. Mechanism of column rocking and stress state of column foot has been explored by theoretical analysis. A nonlinear finite element model of column foot joint has been built and verified using the full-scale test. The verified model is then used to investigate the mechanical behaviors of the joint subjected to cyclic loading with different static vertical loads. Column rocking mechanism and stress distributions of column foot were studied in detail, showing good agreement with the theoretical analysis. Mechanical behaviors of column foot joint and the effects of the vertical load on the seismic behavior of column foot were studied. Result showed that compression stress, restoring moment and stiffness increased with the increase of vertical load. An appropriate vertical load originated by the heavy upper structure would produce certain restoring moment and reset the rocking columns, ensuring the stability of the whole frame.

• CDE review
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• v.22 no.2
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• pp.6-10
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• 2016

This paper presents the kinematics of a walking robot leg based on Jansen mechanism. By using simple mathematics, all trajectories of walking robot leg links can be calculated. A foot point trajectory is used to evaluate the performance of a walking robot leg. Trial and Error method is used to find a best combination of link lengths under certain restrictions. All simulations are performed by Matlab. Ground score, drag score, step size, foot lift, instant speed, and average speed of foot point trajectories are used for selecting the best one.

• KSTLE International Journal
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• v.7 no.2
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• pp.51-55
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• 2006

In order to design an effective foot surface which can provide adequate friction for a self-propelled medical microrobot moving inside the small intestine, frictional mechanisms between the small intestine inner wall and the foot surface of the robot must be understood. In this paper, mechanical interlocking effect was considered to design the surface of the foot that can generate the desired frictional force. The concept of the design was derived from the hookworm that lives inside the small intestine. Hookwarms are known to adhere to the small intestine wall by interlocking with villi on the surface of the small intestine. The interlocking mechanism was considered as the main frictional mechanism for the design of the microrobot foot surface in this work. 2 mm and 6 mm diameter solid and hollow cylindrical shaped foot specimens were designed and tested to assess the frictional force between the specimens and the porcine small intestine specimen.

• Proceeding of EDISON Challenge
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• 2016.03a
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• pp.424-428
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• 2016

This paper presents the kinematics of a walking robot leg based on Jansen mechanism. By using simple mathematics, all trajectories of walking robot leg links can be calculated. A foot point trajectory is used to evaluate the performance of a walking robot leg. Trial and Error method is used to find a best combination of link lengths under certain restrictions. All simulations are performed by Matlab. Ground score, drag score, step size, foot lift, instant speed, and average speed of foot point trajectories are used for selecting the best one.

• Journal of Korean Foot and Ankle Society
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• v.18 no.3
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• pp.124-128
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• 2014

Purpose: The purpose of this study was to assess the treatment outcomes and prognosis of Lisfranc joint fracture and dislocation according to the mechanism of injury and treatment method. Materials and Methods: Twenty six patients with Lisfranc fracture-dislocation who had been treated surgically were included in this retrospective study. The patients were divided into two groups according to mechanism of injury: direct crushing injury (16 patients) and indirect rotational or compressive injury (10 patients). The patients were also divided into three groups according to the surgical methods. The parameters used were radiographic evaluation, patients' subjective satisfaction levels, length of hospital stay, and the American Orthopaedic Foot and Ankle Society (AOFAS) midfoot score. Statistical analysis was performed. Results: The mean postoperative AOFAS midfoot score was 78.7. The mean length of stay was 39.6 days. Statistically significant differences in subjective satisfaction, AOFAS midfoot score, and length of hospital stay were observed between the two groups (p<0.05). However, no significance differences were observed between the three groups who were divided according to the different surgical methods (p>0.05). Conclusion: Mechanism of trauma and the severity of soft-tissue injury were significant prognostic factors affecting the surgical outcomes of Lisfranc joint fracture and dislocation.

• Journal of Astronomy and Space Sciences
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• v.28 no.1
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• pp.79-91
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• 2011

Ongnu (Jade Clepsydra; also called Heumgyeonggaknu) is a water clock was made by Jang Yeong-sil in 1438. It is not only an automatic water clock that makes the sound at every hour on the hour by striking bell, drum and gong, but also an astronomical clock that shows the sun's movement over time. Ongnu's power mechanism used is a water-hammering method applied to automatic time-signal device. The appearance of Ongnu is modeled by Gasan (pasted-paper imitation mountain) and Binpungdo (landscape of farming work scene) is drawn at the foot of the mountain. The structure of Ongnu is divided into the top of the mountain, the foot of the mountain and the flatland. There located are sun-movement device, Ongnyeo (jade female immortal; I) and Four gods (shaped of animal-like immortals) at the top of the mountain, Sasin (jack hour) and Musa (warrior) at the foot of the mountain, and Twelve gods, Ongnyeo (II) and Gwanin on the flatland. In this study, we clearly and systematically understood the time-announcing mechanism of each puppet. Also, we showed the working mechanism of the sun-movement device. Finally, we completely established the 3D model of Ongnu based on this study.