• Geotechnical Engineering
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• v.12 no.3
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• pp.35-48
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• 1996

Reinforced soil structures may experience large local movements between soil and reinforcement. The failure modes of a reinforced structure depend on several factors which are governed by deformation and slipping of the reinforcement. In some cases, pulling out of the reinforcement may occur instead of rupturing, The growing use of geosynthetic liner system for storage of solid and liquid wastes has led to a number of slope instability problems where the synthetic liner may undergo a large amount of stretching and slipping as a result of the loading. The conventional finite element model for the soil-reinforcement interface uses a zero thickness joint element with normal and shear stiffnesses and can only accommodate a small amount of deformation. When a large slippage occurs, the model provides an i ncorrect mechanism for deformation. This paper presents a new interface finite element model which is able to simulate a large amount of slippage between soil and reinforcement. The formulation of the model is presented and the capability of the model is demonstrated using illustrative examples.

• Journal of the Korean Society for Precision Engineering
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• v.25 no.8
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• pp.104-110
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• 2008

The aim of this study ultimately is verifying that PGO gait is more efficient than RGO fur paraplegics because the air muscle assists hip flexion power in heel off movement. The gait characteristics of the paraplegic wearing the PGO or RGO are compared with that of a normal person. PGO with air muscles was used to analyze the walking of patients with lower-limb paralysis, and the results showed that the hip joint flexion and pelvic tilt angle decreased in PGO. In comparison to RGO gait, which is propelled by the movements of the back, PGO uses air muscles, which decreases the movement in the upper limb from a stance phase rate of 79$\pm$4%(RGO) to 68$\pm$8%. The energy consumption rate was 8.65$\pm$3.3 (ml/min/Kg) for RGO, while it decreased to 7.21t2.5(ml/min/Kg) for PGO. The results from this study show that PGO decreases energy consumption while providing support for patients with lower-limb paralysis, and it is helpful in walking for extended times.

• Proceedings of the KIEE Conference
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• 2008.04a
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• pp.73-74
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• 2008

In this study, we developed a robotic gait trainer which induces the active gait training based on predefined continuous proper lower extremity joint movements. AC servo motors and linear actuators were used to control hip and knee joints of patients and the weight support system was used to support the patient's weight during the gait training. We also implemented a Gill program to set the gait training pattern with several training parameters and to confirm states of patients and the system through the visual feedback. The effectiveness of the gait training system will be determined by the long-term clinical experiments in the future. We expect that the developed robotic gait training system could be applied very practically to recover gait abilities for persons with gait disorder.

• Physical Therapy Korea
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• v.12 no.3
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• pp.39-45
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• 2005

Tracking is an experimental paradigm that can be used to study information processing in continuous movements involving accurate, ongoing control of motor performance. The purpose of this study was to identify the effects of knee tracking performance. Six patients with hemiplegia and six age-matched controls participated in the study. The tracking test was administrated. It was composed with regular ranges of $0^{\circ}C$ to $40^{\circ}C$ and randomized range .2 to .4 Hz. Using the Mann-Whitney U test, a comparison was made between subjects who had suffered from stroke and subjects who were well coordinated. The Wilcoxon Matched Pairs Signed Ranks Test was used to compare and analyze the paretic and nonparetic sides of the stroke patients. The results of study were as follows: accuracy index of the tracking test was significantly higher on the control side than paretic and nonparetic sides. Accuracy index scores were significantly higher for nonparetic sides with stroke compared with paretic sides with stroke. This study shows tracking is impaired in paretic and nonparetic knee of subjects with stroke.

• Physical Therapy Korea
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• v.21 no.1
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• pp.55-62
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• 2014

For professional drivers, there is a possibility to have musculoskeletal disorders on ankle joint due to repetitive pedaling operation. Therefore, this study have focused to examine ankle active range of motion (AROM), dorsiflexor strength, and pressure pain threshold (PPT) of tibialis anterior muscle (TA) in taxi drivers compared to a age-matched control group. Thirty male taxi drivers with at least 10 years of driving experience and thirty male sedentary workers were evaluated for ankle AROM, dorsiflexor strength, and PPT of TA. Multiple independent t-tests were used to identify significant differences between two groups. For the results, taxi drivers had significantly less AROM in dorsiflexion and greater AROM in external tibial rotation compared to the control group. Also, dorsiflexor strength and PPT of TA in taxi drivers was significantly lower than in the control group. This study indicates that the repetitive ankle movements associated with driving have an effect on ankle AROM, dorsiflexor strength, and PPT of TA and may lead to work-related musculoskeletal disorders on ankle. Professional drivers may need to be educated to prevent a potential musculoskeletal disorders associated with repetitive movement.

• The Journal of Korean Academy of Orthopedic Manual Physical Therapy
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• v.8 no.1
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• pp.25-30
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• 2002

The main purpose of this article is to suggest a modified SNAGs manual method in based of Mulligan techniques. And this study aimed to resolve the back pain which has combined movement dysfunction in lumbar spine, in addition to upgrade of manual therapy technique in clinical field. The results of this study were as following; 1. The first introduction of SNAGs in Korea is the 'International Mulligan Concepts and Techniques Seminar' by Prof. Russell M. Woodman(Quinnipiac college, USA), 1998. SNAGs is defined a mobilization with movement manual therapy that facet joints of the lesion mobilized to anterior-superior direction according to the treatment plane in apophyseal joint of hypomobility. 2. A treatment mechanism of the SNAGs is, Mulligan say, HIVD which is the result of posterior disk bulging from a increased between intervertebral pressure due to hypo-mobile of facet joints in abnormal spine, so therapist should be necessary mobilization of zygophyseal joints especially in disk lesion. 3. Because Mulligan does not yet mentioned SNAGs techniques about a back pain with combined movements dysfunction, so we suggest a modified SNAGs method for manual therapy of back pain patients due to combined movement dysfunction at lumbar.

• Proceedings of the KSME Conference
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• 2007.05a
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• pp.939-944
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• 2007

Generally, development of a robot capable of fast movements or high payloads is progressed by the analysis of dynamic characteristics, DOF positioning, actuator selection, structure of links, and so on. This paper highlights the design of a robot manipulator handled by a human for man-machine cooperation. The requirements of the proposed system include its having multi-DOF(Degree of Freedom)and the capacity for a high payload in the condition of its maximum reach. The primary investigation factors are motion range, performance within the motion area, and reliabilityduring the handling of heavy materials. Traditionally, the mechanical design of robots has been viewed as a problem of packaging motors and electronics into a reasonable structure. This process usually transpires with heavy reliance of designerexperience. Not surprisingly, the traditional design process contains no formally defined rules for achieving desirable results, as there is little opportunity for quantitative feedback during the formative stages. This work primarily focuses on the selection of proper joint types and link lengths, considering a specific task type and motion requirements of the heavy material handling.

• Korean Journal of Applied Biomechanics
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• v.14 no.2
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• pp.1-14
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• 2004

This study was intended to contribute to allowing athletes to raise a technical understanding of two motions of high difficulty such as the Swallow motion and the Nakayama motion and enhance their competitive power by analysing the kinematical factors required to link those two motions on the competitive scene on the rings for current national athletes. For this purpose, the game of the ring event was videotaped for male heavy gymnasts participating in the final elimination match of the 2004 Athens Olympic Games. This study attempted to select the performing motions of the final 1st-and 2nd-place athletes performing the linking motions from the Swallow motion and the Nakayama motion using the DLT(direct linear transformation) method. As a result, it arrived at the following conclusion : A1 properly performed the flexing and extending movements using the angular velocity of the segment and joint as the switching motion using the body at the time of linking the motion from the Swallow skill to the Nakayama skill. A2 was evaluated to perform the skill taking the form of depending on the force at the static state. Therefore, it is thought that A1 should take care of shaking at the time of using the elasticity of the body. It is thought that in case of A2 the proper use of the elasticity of the body take care of shaking at the switching motion while taking advantage of the force will contribute to his competitive power.

• Korean Journal of Applied Biomechanics
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• v.14 no.2
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• pp.139-152
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• 2004

Two subjects, an expert and a novice, were carefully selected based upon their foot speed. Three dimensional videography was used in the assessment of roundhouse kicking of the Tae-kwon-Do. The local reference frames were imbedded at the trunk, pelvis, thigh and shank. Anatomical angular displacement at the joints were measured by projecting the upper segment's local axes to the lower segment's local reference planes. The local axes again projected to the global reference frames and absolved each segment's movement. The peaks of the anatomical angular displacement curve assessed as the countermovements and the angular movements of the segments in the global space absolved in light of the occurrence of the countermovements. The expert showed larger and more countermovements than the novice at the all segments. The counterrnovement occured more clearly at the trunk than the hip and knee joint and during the preparative movement phase. These countermovements occurrence were due to either by turning upper or lower segments and controlled by the turning direction and sequence of the two nearby segments. It was revealed that the countermovements of the trunk during the preparative movement phase was the important factor of the power kicking.

• Journal of Institute of Control, Robotics and Systems
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• v.11 no.1
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• pp.77-83
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• 2005

This paper deals with determination of motions of a humanoid robot using genetic algorithm. A humanoid robot has some problems of the structural instability basically. So, we have to consider the stable walking gait in gait planning. Besides, it is important to make the smoothly optimal gait for saving the electric power. A mobile robot has a battery to move autonomously. But a humanoid robot needs more electric power in order to drive many joints. So, if movements of walking joints don't maintain optimally, it is difficult for a robot to have working time for a long time. Also, if a gait trajectory doesn't have optimal state, the expected life span of joints tends to be decreased. To solve these problems, the genetic algorithm is employed to guarantee the optimal gait trajectory. The fitness functions in a genetic algorithm are introduced to find out optimal trajectory, which enables the robot to have the less reduced jerk of joints and get smooth movement. With these all process accomplished by a PC-based program, the optimal solution could be obtained from the simulation. In addition, we discuss the design consideration for the joint motion and distributed computation of the humanoid, ISHURO, and suggest its result such as the structure of the network and a disturbance observer.