• 한국운동역학회지
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• 제21권2호
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• pp.181-187
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• 2011

The purpose of this study was to identify major factors on pirouette in ballet, and especially angle, Center of Mass(CM) & muscle activity aspects. The data were collected by using Motion Analysis System with 12 cameras to analyze kinematic variables with 120 Hz and Electromyography(EMG; 4,000 Hz) & Force Platform(1,000 Hz) to analyze kinetic variables. The subjects of this study were 8 female ballet dancers. The results as follow. First of all, full extension of knee joint and full plantar flexion of ankle joint appeared at the similar point. Secondly, in the rotational phase, total movement of segments in Good motion is smaller than that of Bad motion(in Good motion, head movement 2.70 cm, right shoulder movement 0.72 cm, left shoulder 4.26 cm, left wrist 17.4 mm smaller than Bad motion). Third, CoP distance of Good motion is 11.76 mm, and CoP distance of Bad motion is 11.76 mm, so Good motion is 5.98 mm smaller). Lastly, Pirouette need more retus femur activity than gastrocnemius activity in extention phase and rotation phase of support leg.

• 한국운동역학회지
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• 제16권3호
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• pp.85-94
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• 2006

The purpose of this study was to analyze the kinematics variables of during forehand stroke by stance patterns. Eight high school tennis players were chosen for the study, who have never been injured for last six months, in Busan. They performed horizontal swing and vertical swing that it was done each five consecutive trial in the condition of square, open and semi-open stance. It was filmed by 6 video camera and used with 3-dimensional motion analyzer system. The following kinematic variables were analyzed in relation to angle of segment( shoulder, hip and knee joint). The conclusion were as follow: 1. The angle of hip joint represented at impact that horizontal swing was not significant difference by stance patterns but vertical swing was increased in open stance than square and semi-open stance. 2. The angle of both knee was not significant difference between all stance types and swing patterns. 3. The angle of shoulder, hip and knee joint rotation showed that open stance was increased than square and semi-open stance in all swing types and event.

• 제어로봇시스템학회논문지
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• 제20권9호
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• pp.936-941
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• 2014

Walking mechanisms are very important for legged robots to ensure their stable locomotion. In this research, Klann-linkage is suggested as a walking mechanism for a water-running robot and is optimized using level average analysis. The structure of the Klann-linkage is introduced first and design variables for the Klann-linkage are identified considering the kinematic task of the walking mechanism. Next, the design problem is formulated as a path generation optimization problem. Specifically, the desired path for the foot-pad is defined and the objective function is defined as the structural error between the desired and the generated paths. A process for solving the optimization problem is suggested utilizing the sensitivity analysis of the design variables. As a result, optimized lengths of Klann-linkage are obtained and the optimum trajectory is obtained. It is found that the optimized trajectory improves the cost function by about 62% from the initial one. It is expected that the results from this research can be used as a good example for designing legged robots.

• 한국전문물리치료학회지
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• 제3권2호
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• pp.36-41
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• 1996

The purpose of this study was to determine whether the biomechanical variables of the walking patterns of the obese children compared with those of normal children would revealing significant differences. Normal(N=25) and obese(N=19) subjects were screened based on a health record which was examined to eliminate any subjects who had any pathological condition related to their gait. Data for a minimum of 5 repeated walking trials were collected using a stop watch and a tape measure. Basic kinematic analyses yielded data based on the following variables : stride length divided by leg length, and cadence divided by leg length. This measurement data was classified by the Obesity Index calculated from by height, weight data. Results showed no significant difference among normal, obese and subjects(p>.05). Difficulties in formulating the experimental condition and poor equipment quality are thought to be reason for the inconclusive results. Future studies might include medical complications such as tibia vara, genu valgum, other diseases caused by obesity.

• 한국운동역학회지
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• 제21권1호
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• pp.85-95
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• 2011

Three-dimensional(3D) motion analysis is a useful tool for analyzing sports performance. During the last few decades, advances in motion analysis equipment have enabled us to perform more and more complicated biomechanical analyses. Nevertheless, considering the complexity of biomechanical models and the amount of data recorded from the motion analysis system, subsequent processing of these data is required for event-specific motion analysis. The purpose of this study was to develop a basic golf swing analysis algorithm using a state-of-the-art VICON motion analysis system. The algorithm was developed to facilitate golf swing analysis, with special emphasis on 3D motion analysis and high-speed motion capture, which are not easily available from typical video camera systems. Furthermore, the developed algorithm generates golf swing-specific kinematic and kinetic variables that can easily be used by golfers and coaches who do not have advanced biomechanical knowledge. We provide a basic algorithm to convert massive and complicated VICON data to common golf swing-related variables. Future development is necessary for more practical and efficient golf swing analysis.

• 제어로봇시스템학회논문지
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• 제14권1호
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• pp.88-94
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• 2008

In this paper, a design method of a missile guidance command is presented considering the dynamics of missile control systems. The design of a new guidance command is based on the well-known PNG(propotional navigation guidance) laws. The missile control system dynamics cause the time-delays of the PN guidance command and degrade the performance of original guidance laws which are designed under the assumption of the ideal missile control systems. Using a backstepping method, these time-delay effects can be compensated. In order to implement the guidance command developed by the backstepping procedure, it is required to measure or calculate the successive time-derivatives of the original guidance command, PNG and other kinematic variables such as the relative distance. Instead of directly using the measurements of these variables and their successive derivatives, a simple disturbance observer technique is employed to estimate a guidance command described by them. Using Lyapunov method, the performance of a newly developed guidance command is analyzed against a target maneuvering with a bounded and time-varying acceleration.

• 한국운동역학회지
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• 제23권1호
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• pp.19-24
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• 2013

The aim of the study was a quantitative analysis of elite athlete's $540^{\circ}$ Dwihuryeochagi and effects of ground movements to the jumping height and kicking velocity. Eleven elite players(Taekwondo demonstration team) participated in this study. In order to get the kinetic and kinematic variables, ten Vicon cameras and a force plate were used. Foot segment velocity(FSV), vertical ground reaction force(GRF), impulse, ground time(GT) in phase 1, trunk angular velocity(TAV), vertical center of gravity(COG), flight time(FT) in phase 2 and kicking leg segment velocity(KSV) in phase 3 were measured and analyzed. Results indicated that there were similar patterns of variables among phases between subjects. Non-significant correlation(r=.145) between flight time(FT) and impulse was found. Also non-significant correlation(r=.119) between center of gravity(COG) and impulse was found. In conclusions, there were similar strategies in phase 1, phase 2, and phase 3 between subjects.

• 제어로봇시스템학회논문지
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• 제22권1호
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• pp.53-58
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• 2016

Various jumping robot platforms have been developed to carry out missions such as rescues, explorations, or inspections of dangerous environments. We suggested a jumping robot platform using energy conversion of the elastic body like the bar of a pole vault, which is the main part in which elastic force occurs. The compliant link was optimized by an optimization method based on Taguchi methodology, and the robot's leaping ability was improved. Among the parameters, the length, width, and thickness of the link were selected as design variables first while the others were fixed. The level of the design variables was settled, and an orthogonal array about its combination was made. In the experiment, dynamic simulations were conducted using the DAFUL program, and response table and sensitivity analyses were performed. We found optimized values through a level average analysis and sensitivity analysis. As a result, the maximum leaping height of the optimized robot increased by more than 6.2% compared to the initial one, and these data will be used to design a new robot.

• Structural Engineering and Mechanics
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• 제66권1호
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• pp.61-73
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• 2018

In this article, a higher shear deformation theory (HSDT) is improved to consider the influence of thickness stretching in functionally graded (FG) plates. The proposed HSDT has fewer numbers of variables and equations of motion than the first-order shear deformation theory (FSDT), but considers the transverse shear deformation influences without requiring shear correction coefficients. The kinematic of the present improved HSDT is modified by considering undetermined integral terms in in-plane displacements and a parabolic distribution of the vertical displacement within the thickness, and consequently, the thickness stretching influence is taken into account. Analytical solutions of simply supported FG plates are found, and the computed results are compared with 3D solutions and those generated by other HSDTs. Verification examples demonstrate that the developed theory is not only more accurate than the refined plate theory, but also comparable with the HSDTs which use more number of variables.

• 한국운동역학회지
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• 제17권3호
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• pp.115-124
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• 2007

The purpose of this study was to analyze the kinematics variables of upper limb joint during forehand stroke by swings patterns. Eight high school tennis players were chosen for the study, who have never been injured for last six months, in Busan. They performed horizontal swing and vertical swing that it was done each five consecutive trial in the condition of square, semi-open and open stance. It was filmed by 6 video camera and used with 3-dimensional motion analyzer system. The following kinematic variables were analyzed in relation to angle of joint(shoulder, elbow and wrist joint). The conclusion were as follow: 1. The angle of right shoulder joint represented all event that both swing were shown similar pattern in swing type and stance pattern. 2. All event in the angle of elbow joint had consistent with that except E2, horizontal and vertical swings in square stance. 3. All event in the angle of wrist joint was show to similar pattern except E2, horizontal and vertical swing in open stance.