• Korean Journal of Applied Biomechanics
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• v.26 no.2
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• pp.183-190
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• 2016

Objective: The objective of this study is to present a scientific basis for ballet dancer training methods by analyzing the relationships between subjective assessment of the ballet movement 'Grand pas de chat' and kinematic and electromyographic factors. Method: The subjects were 14 professional dancers with 15 years of experience on average. Four cameras and a wireless electromyogram were used to examine kinematic factors, and the filmed videos were analyzed by 3 experts for subjective assessment. Results: Although no differences in kinematic factors were found between the excellent dancer group and the non-excellent dancer group divided based on the experts' assessment, some difference was found in electromyographic factors, especially in relation to the gastrocnemius muscle, rectus femoris muscle, and erector spinae muscle. A relationship between subjective assessment and kinematic and electromyographic factors was found, and factors such as right-side rectus femoris activation, time required, left-side gastrocnemius activation, and front-back displacement affected subjective assessment. Conclusion: This study showed a relationship between subjective assessment and kinematic and electromyographic factors. To receive higher scores in subjective assessment, it is necessary to extend the hang time by using the lower limb muscles. The findings of this study also indicate the necessity of weight training in order to improve dancing techniques.

• Journal of Institute of Control, Robotics and Systems
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• v.8 no.9
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• pp.764-775
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• 2002

A kinematic and dynamic optimal design of a new parallel-type rolling mill based upon Stewart platform manipulator is investigated. To provide sufficient degrees-of-freedom in the rolling process and the structural stability of each stand, a parallel manipulator with six legs is considered. The objective of this new parallel-type rolling mill is to permit an integrated control of the strip thickness, strip shape, pair crossing angle, uniform wear of the rolls, and tension of the strip. By splitting the weighted Jacobian matrices Into two parts, the linear velocity, angular velocity, force, and moment transmissivities are analyzed. A manipulability measure, the ratio of the manipulability ellipsoid volume and the condition number of a split Jacobian matrix, is defined. Two kinematic parameters, the radius of the base and the angle between two neighboring Joints, are optimally designed by maximizing the global manipulability measure in the entire workspace. The maximum force needed in the hydraulic actuator is also calculated using the structure determined through the kinematic analysis and the Plucker coordinates. Simulation results are provided.

• Journal of the Korean Society for Precision Engineering
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• v.33 no.7
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• pp.579-586
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• 2016

This paper describes kinematic analysis of a 6-degrees-of-freedom (DOF) ultra-precision positioning stage based on a flexure hinge. The stage is designed for processes which require ultra-precision and high load capacities, e.g. wafer-level precision bonding/assembly. During the initial design process, inverse and forward kinematic analyses were performed to actuate the precision positioning stage and to calculate workspace. A two-step procedure was used for inverse kinematic analysis. The first step involved calculating the amount of actuation of the horizontal actuation units. The second step involved calculating the amount of actuation of the vertical actuation unit, given the the results of the first step, by including a lever hinge mechanism adopted for motion amplification. Forward kinematic analysis was performed by defining six distance relationships between hinge positions for in-plane and out-of-plane motion. Finally, the result of a circular path actuation test with respect to the x-y, y-z, and x-z planes is presented.

• Journal of the Korean Society of Physical Medicine
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• v.13 no.3
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• pp.113-120
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• 2018

PURPOSE: This study was conducted to investigate the characteristics of a specific functional shoe in terms of the range of motion (ROM) of ankle and foot joints during walking when compared to a standardized shoe. METHODS: Kinematic ROM data pertaining to ankle, tarsometatarsal, and metatarsophalangeal joints were collected from twenty-six healthy individuals during walking using a ten-camera motion analysis system. Kinematic ROM of each joint in three planes was obtained over ten walking trials consisting of two different shoe conditions. Visual3D motion analysis was finally used to coordinate the kinematic data. All kinematic ROM data were interpolated using a cubic spline algorithm and low-pass filtered with a cutoff frequency of 6 Hz for smoothing. RESULTS: The overall ROM of the ankle joint in the sagittal and coronal planes when wearing the specific functional shoe was significantly decreased in both ankles during walking when compared to wearing a standard shoe (p<.05). Significantly more flexibility was observed when wearing the specific functional shoe in the tarsometatarsal and metatarsophalangeal joints compared to a standard shoe (p<.05). CONCLUSION: Although clinical application of the specific functional shoe has shown clear positive effects on knee and ankle moments, the results of this study provide important background information regarding the kinematic mechanisms of these effects.

• Journal of Astronomy and Space Sciences
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• v.37 no.3
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• pp.199-208
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• 2020

This paper presents a kinematic ephemeris generator for Korea Pathfinder Lunar Orbiter (KPLO) and its performance test results. The kinematic ephemeris generator consists of a ground ephemeris compressor and an onboard ephemeris calculator. The ground ephemeris compressor has to compress desired orbit propagation data by using an interpolation method in a ground system. The onboard ephemeris calculator can generate spacecraft ephemeris and the Sun/Moon ephemeris in onboard computer of the KPLO. Among many interpolation methods, polynomial interpolation with uniform node, Chebyshev interpolation, Hermite interpolation are tested for their performances. As a result of the test, it is shown that all the methods have some cases that meet requirements but there are some performance differences. It is also confirmed that, the Chebyshev interpolation shows better performance than other methods for spacecraft ephemeris generation, and the polynomial interpolation with uniform nodes yields good performance for the Sun/Moon ephemeris generation. Based on these results, a Kinematic ephemeris generator is developed for the KPLO mission. Then, the developed ephemeris generator can find an approximating function using interpolation method considering the size and accuracy of the data to be transmitted.

• Journal of Astronomy and Space Sciences
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• v.29 no.3
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• pp.269-274
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• 2012

Kinematic global positioning system precise point positioning (GPS PPP) technology is widely used to the several area such as monitoring of crustal movement and precise orbit determination (POD) using the dual-frequency GPS observations. In this study we developed a kinematic PPP technology and applied 3-pass (forward/backward/forward) filter for the stabilization of the initial state of the parameters to be estimated. For verification of results, we obtained GPS data sets from six international GPS reference stations (ALGO, AMC2, BJFS, GRAZ, IENG and TSKB) and processed in daily basis by using the developed software. As a result, the mean position errors by kinematic PPP showed 0.51 cm in the east-west direction, 0.31 cm in the north-south direction and 1.02 cm in the up-down direction. The root mean square values produced from them were 1.59 cm for the east-west component, 1.26 cm for the south-west component and 2.95 cm for the up-down component.

• 제어로봇시스템학회:학술대회논문집
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• 1996.10b
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• pp.743-746
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• 1996

A hybrid control scheme to regulate the force and position by dual arms is proposed, where two arms are treated as one arm in a kinematic viewpoint. Our approach is different from other hybrid control approaches which consider robot dynamics, in the sense that we employ a purely kinematic based approach for hybrid control, with regard to the nature of position-controlled industrial robots. The proposed scheme is applied to sawing task. In the sawing task, the trajectory of the saw grasped by dual arms is planned in an offline fashion. When the trajectory of the saw is planned to follow a line in a horizontal plane, 3 position parameters are to be controlled(i.e, two translational positions and one rotational position). And a certain level of contact force has to be controlled along the vertical direction(i.e., minus z-direction) not to loose the contact with the object to be sawn. Typical feature of sawing task is that the contact position where the force control is to be performed is continuously changing. Therefore, the kinematic mapping between the force controlled position and the joint actuators has to be updated continuously. The effectiveness of the proposed control scheme is experimentally demonstrated. The proposed hybrid control scheme can be applied to arbitrary dual arm systems, regardless of their kinematic structure and the number of actuated joints.

• Journal of the Korean Society for Precision Engineering
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• v.22 no.11 s.176
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• pp.72-81
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• 2005

A new spherical-type 3-degree-of-freedom parallel mechanism consisting of a two degree-of-freedom parallel module and a serial module is proposed. Two alternative designs for the serial sub-chain are suggested and compared. The first design employs RU joint arrangement for the serial sub chain structure. The second design incorporates a gear chain to drive the distal revolute joint of the serial sub-chain from the base platform of the mechanism. This modification significantly improves kinematic characteristics of the mechanism within its workspace. Firstly, the closed-form solutions of both the forward and the reverse position analysis are derived. Secondly, the first-order kinematic model with respect to three inputs which are located at the base is derived. Thirdly, it is confirmed through simulation that the modified mechanism has much more improved isotropic characteristic throughout the workspace of the mechanism. Lastly, the proposed mechanism is implemented to verify the results from this analysis.

• Korean Journal of Applied Biomechanics
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• v.20 no.3
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• pp.277-284
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• 2010

The purpose of this study was to investigate the trunk rotation type by wheel and axle. In order to analysis, 3D-motion analysis and electromyography were conducted on kinematic variables, impulse, average-EMG and integrated-EMG. Twelve healthy (age: $21.8{\pm}2.2$ yrs, height: $175.4{\pm}5.0cm$, weight: $66.7{\pm}6.4kg$) participated in the experiment. The results were as follows; in hand's velocity and acceleration, wheel and axial rotating movement using kinematic chain(type 3) were much faster. In impulse, type 3 was much stronger. In average-EMG, right and left, latissimus dorsi muscles was much stronger. In integrated-EMG, left erector spinae, right/left latissimus dorsi, and left external oblique muscles was much stronger. These results considered that, in the trunk rotation utilizing the kinematic chains action, latissimus dorsi muscles highly contribute to the muscle utilization that makes the rotating movement maximally effective.

• Korean Journal of Applied Biomechanics
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• v.23 no.4
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• pp.319-326
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• 2013

The objective of this study is to help golfers to select adequate putters and to provide golfers basic scientific data for improving athletic performance by showing differences of kinematic variables according to the shape of putter head. In this research three right-handed male pro-golfer who are listed at KPGA were studied and three video camera (GR-HD1KR, JVC, Japan) were used and recording speed was 60 frame/sec during the research. In this study kinematic variables were calculated using Kwon3D XP program and analysed on the 4 events and 3 phases. This study showed the following results : (1) The swing of heel-toe putter showed longer time than that of face balanced putter, and there are statistical significant difference of kinematic variables of each objective (2) As of the trajectory of putter head, heel-toe putter showed more approximating curve trajectory than that of in-between, face balanced putter on the X-axis (3) heel-toe putter showed longer distance follow-through than that of other putters by statistically significant difference on the Y-axis (4) Heel-toe putter showed longer distance swing trajectory over the ground than that of other putters by statistically significant difference on the Z-axis.