• Tunnel and Underground Space
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• v.8 no.4
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• pp.287-295
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• 1998

Limit equilibrium method is widely used for the stability analysis of soil slopes. In jointed rock slopes however, the failure of the slope is largely dependent upon the strength and deformability of the joints in the rock mass and quite often failure occurs along the joints. This paper describes the use of ubiquitous joint model for the stability analysis of the jointed rock slopes. This model is essentially an anisotropic elasto-plastic model and can simulate two sets of joint in arbitrary orientations. Validation of the developed with the factor of safety equal to unity was selected when the shape of the failure plane is assumed log spiral. Then the factor of safety of the rock slope having two perpendicular joint sets was calculated while rotating joint orientations. Rusults were compared with limit equilibrium solutions on soil slopes having equivalent soil properties when plane sliding was assumed. Developed model predicted the factor of safety of jointed rock slope in a reasonable accuracy when joint spacing is sufficiently small.

• Journal of muscle and joint health
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• v.18 no.2
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• pp.182-191
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• 2011

Purpose: The purpose of this study is to compare the effects of board training and complex training on ankle stability in taekwondo college students with a history of ankle sprain. Methods: Twenty-seven taekwondo college students were randomly assigned into a board training (BTG, n=9), complex training (CTG, n=9), or control groups (CG, n=9). BTG carried out disk and trampoline training 3 times a week for 8 weeks. CTG carried out resistive and plyometric training 3 times a week for 8 weeks. All subjects completed ankle stability test for static and dynamic balance in anterior/posterior and medial/lateral stability with New Balance System (BIODEX Medical System, USA). Results: There were no significant differences between three groups in ankle stability. Those who participated in BTG significantly improved static balance of left foot in anterior/posterior stability, and dynamic balance of both feet in mediolateral stability, but there were no change in CTG. Conclusion: Board training is more improved ankle stability in taekwondo college students with a history of ankle sprain than complex training.

• Korean Journal of Applied Biomechanics
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• v.25 no.1
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• pp.29-37
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• 2015

Objective : The purpose of this study was to investigate the biomechanical properties of shock absorption strategy and postural stability during the drop landing for each types. Methods : The motions were captured with Vicon Motion Capture System, with the fourteen infra-red cameras (100Hz) and synchronized with GRF(ground reaction force) data(1000Hz). Ten male soccer players performed a drop landing with single-leg and bi-legs on the 30cm height box. Dependent variables were the CoM trajectory and the Joint Moment. Statistical computations were performed using the paired t-test and ANOVA with Turkey HSD as post-hoc. Results : The dominant leg was confirmed to show a significant difference between the left leg and right leg as the inverted pendulum model during Drop Landing(Phase 1 & Phase 2). One-leg drop landing type had the higher CoM displacement, the peak of joint moment with the shock absorption than Bi-leg landing type. As a lower extremity joint kinetics analysis, the knee joint showed a function of shock absorption in the anterior-posterior, and the hip joint showed a function of the stability and shock absorption in the medial-lateral directions. Conclusion : These findings indicate that the instant equilibrium of posture balance(phase 1) was assessed by the passive phase as Class 1 leverage on the effect of the stability of shock absorption(phase 2) assessed by the active phase on the effect of Class 2 leverage. Application : This study shows that the cause of musculo-skeletal injuries estimated to be focused on the passive phase of landing and this findings could help the prevention of lower damage from loads involving landing related to the game of sports.

• Structural Engineering and Mechanics
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• v.62 no.5
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• pp.619-629
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• 2017

This paper focuses on the study of complete dynamic modeling and maximum dynamic load carrying capacity computation of N-flexible links and N-flexible joints mobile manipulator undergoing large deformation. Nonlinear dynamic analysis relies on the Timoshenko theory of beams. In order to model the system completely and precisely, structural and joint flexibility, nonlinear strain-displacement relationship, payload, and non-holonomic constraints will be considered to. A finite element solution method based on mixed method is applied to model the shear deformation. This procedure is considerably more involved than displacement based element and shear deformation can be readily included without inducing the shear locking in the element. Another goal of this paper is to present a computational procedure for determination of the maximum dynamic load of geometrically nonlinear manipulators with structural and joint flexibility. An effective measure named as Moment-Height Stability (MHS) measure is applied to consider the dynamic stability of a wheeled mobile manipulator. Simulations are performed for mobile base manipulator with two flexible links and joints. The results represent that dynamic stability constraint is sensitive when calculating the maximum carrying load. Furthermore, by changing the trajectory of end effector, allowable load also changes. The effect of torsional spring parameter on the joint deformation is investigated in a parametric sensitivity study. The findings show that, by the increase of torsional stiffness, the behavior of system approaches to a system with rigid joints and allowable load of robot is also enhanced. A comparison is also made between the results obtained from small and large deformation models. Fluctuation range in obtained figures for angular displacement of links and end effector path is bigger for large deformation model. Experimental results are also provided to validate the theoretical model and these have good agreement with the simulated results.

• Proceedings of the Korean Geotechical Society Conference
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• 2002.03a
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• pp.651-656
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• 2002

In general, the most important problem in slope stability analysis is that there is no definite way to describe the natural three-dimensional Joint network. Therefore, the many approaches were tried to anlayze the slope stability. Numerical modeling approach is one of the branch to resolve the complexity of natural system. UDEC, FLAC, and SWEDGE are widely used commercial code for the purpose on stability analysis. For the purpose on the more appropriate application of these kind of code, however, three-dimensional distribution of joint network must be identified in more explicit way. Remaining problem is to definitely describe the three dimensional network of joint and bedding, but it is almost impossible in practical sense. Three dimensional joint generation method with random number generation and the results of generation to UDEC have been applied to settle the refered problems in field site. However, this approach also has a important problem, and it is that joint network is generated only once. This problem lead to the limitation on the application to field case, in practical sense. To get rid of this limitation, Monte Carlo Simulation is proposed in this study 1) statistical analysis of input values and definition of the applied system with statistical parameter, 2) instead of the consideration of generated network as a real system, generated system is just taken as one reliable system, 3) present the design parameters, through the statistical analysis of ouput values Results of this study are not only the probability of failure, but also area of failure block, shear strength, normal strength and failure pattern, and all of these results are described in statistical parameters. The results of this study, shear strength, failure area, pattern etc, can provide the direct basement on the design, cutoff angle, support pattern, support strength and etc.

• The Journal of Korean Physical Therapy
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• v.28 no.1
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• pp.27-32
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• 2016

Purpose: The purpose of this study is to examine the effects of sensorimotor training on knee joint stability after anterior cruciate ligament reconstruction. Methods: The subjects were sixteen 16 adults who received anterior cruciate reconstruction by arthroscopy, and underwent sensorimotor training for which was to have them maintenanceain of a standing position with a step Balance ball on the affected side over 30 degrees knee flexion with 100% weight bearing for 15-20 seconds. Before the genuine experiment commenced, the Lysholm scale was had been used to assess functional disorders on the affected knee joint. KT-2000 Arthrometer measurement equipment was used to measure anterior displacement of tibia against to femur before and after the sensorimotor training. Results: There was significant relaxation on the affected side in tibia anterior displacement of the affected and sound sides on in supine position before the sensorimotor training. There was little significant difference in tibia anterior displacement of the affected knee joints on in the supine position before and after the sensorimotor training. The results also showed that there was a reduction in the difference of tibia anterior displacement of the affected knee joints on in the standing position. These results suggest that the effects of sensorimotor training on knee joint stability after anterior cruciate ligament reconstruction is to induce the change of tibia anterior displacement against femur and the variation of muscles activation. Conclusion: The sensorimotor training may contribute to the improvement of joint functional stability in people who are in post-operation state and with orthopedic musculoskelectal injuries.

• Clinics in Shoulder and Elbow
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• v.13 no.1
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• pp.141-145
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• 2010

Purpose: Understanding elbow biomechanics is necessary to understand the pathophysiologic mechanism of elbow injury and to provide a scientific basis for clinical practice. This article provides a summary of key concepts that are relevant to understanding common elbow injuries and their management. Materials and Methods: The biomechanics of the elbow joint can be divided into kinematics, stability and force transmission through the elbow joint. Active and passive stabilizers include bony articular geometry; soft tissues provide joint stability, compression force and motion. Results and Conclusion: Knowledge of elbow biomechanics will help (i) advance surgical procedures and trauma management, (ii) develop new elbow prostheses and (iii) stimulate future research.

• The Journal of the Korea institute of electronic communication sciences
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• v.8 no.11
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• pp.1665-1674
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• 2013

In this paper, we propose a genetic algorithm(GA) based locomotion method of a quadruped robot with waist joint, which makes a quadruped robot walk on the slop efficiently. In the proposed method, we first derive the kinematic model of a quadruped robot with waist joint and then set the gene and the fitness function for GA. In addition, we determine the best attitude for a quadruped robot and the landing point of a foot in the walk space, which has the optimal energy stability margin(ESM). Finally, we verify the effectiveness of the proposed method by comparing with the performance of the previous method through the computer simulations.

• Proceedings of the KIEE Conference
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• 2003.11b
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• pp.247-250
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• 2003

In this paper, we propose a robust controller for motion control of n-link robot manipulators using visual feedback. The desired joint velocity and acceleration is obtained by the feature-based visual systems and is used in the joint velocity control loop for trajectory control of the robot manipulator. We design a robust controller that compensates for bounded parametric uncertainties of robot dynamics. The stability analysis of robust joint velocity control system is shown by Lyapunov Method. The effectiveness of the proposed method is shown by simulation results on the 5-link robot manipulators with two degree of freedom.

• International Journal of Control, Automation, and Systems
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• v.4 no.4
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• pp.495-505
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• 2006

A class of robust control for flexible joint manipulators with nonlinearity mismatched uncertainty is designed based on Lyapunov approach. The uncertainties are unknown but their values are within certain prescribed sets. No statistic information of the uncertainties is imposed. The control which utilizes state transformation via virtual control is proposed. The resulting robust control guarantees practical stability for the transformed system and later the stability for the original system is proved. The designed robust control is implemented by experiments in a 2-link flexible joint manipulator.