• Korean Journal of Applied Biomechanics
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• v.16 no.1
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• pp.109-117
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• 2006

The purpose of this study was done in order to investigate the Kinematical variables of the Rybalko motion on the Horizontal bar using the 3-dimensional cinematographic method. For this study, three excellent athletes take part in a 2003 Daegue universid game were chosen. The subject,s Rybalko motion was filmed with S-VHS camera at the speed of 60 fields per second and digitized the each fields. And the Kwon3D 3.1 version program was employed to obtain 3-dimensional data. As a result of this study. 1. A total time spent for performing Rybalko skill was Mean $2.52{\pm}0.13sec$. From starting down swing to releasing right hand the Mean $0.84{\pm}0.24sec$ was taken. 2. In the event 3 of Rybalko motion, that is, the moment which the right-hand is released on the bar, the center of mass must is employed at the position above the horizontal line of bar. In this research, the average vertical displacement(z axe) of center of mass shows $47.87{\pm}3.14cm$. 3. In the event 5, that is, the moment which the right-hand is catched again on the bar, the center of mass is employed at the position before the vertical line of bar. In this research, the average horizontal displacement(z axe) of center of mass shows $47.87{\pm}3.14cm$. 4. It has been seen that, at the moment of release of right-hand, lateral variation of center of mass is 13.395cm, vertical variation of center of mass is 7.41cm Thus, it is concluded that lateral variation of center of mass should be reduced for high grade to be acquired. 5. It has been founded that high speed of down swing influences speed of up swing, and that, in the motion of twist, the horizontal speed is little changed.

• Journal of the Korean Institute of Intelligent Systems
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• v.21 no.5
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• pp.537-542
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• 2011

A mirror neuron is a neuron fires both when an animal acts and when the animal observes the same action performed by another. We propose a method of 3D reconstruction for occluded object motion tracking like Mirror Neuron System to fire in hidden condition. For modeling system that intention recognition through fire effect like Mirror Neuron System, we calculate depth information using stereo image from a stereo camera and reconstruct three dimension data. Movement direction of object is estimated by optical flow with three-dimensional image data created by three dimension reconstruction. For three dimension reconstruction that enables tracing occluded part, first, picture data was get by stereo camera. Result of optical flow is made be robust to noise by the kalman filter estimation algorithm. Image data is saved as history from reconstructed three dimension image through motion tracking of object. When whole or some part of object is disappeared form stereo camera by other objects, it is restored to bring image date form history of saved past image and track motion of object.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2005.06a
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• pp.615-618
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• 2005

All over the world, many kinds of micro-actuators were already developed for various applications. The actuators are using various principles such as electromagnetic, piezoelectric and thermopneumatic etc. The most of the micro-actuators have been made using 2D based MEMS technology. In these actuators, it is difficult to drive 3-dimensional motion. This characteristic gives the limit of actuator application. However, micro-stereolithography technology has made it possible to fabricate freeform three-dimensional microstructures. In this technology, 2-dimensional micro-shape layer is cumulated on the other layers. This layer-by-layer process is the main principle to fabricate 3-dimensioal micro-structures. In this research, a micro-bellows actuator that is vertically moving was developed using the micro-stereolithography technology. When pressure was applied into the bellows, a non-contact actuating motion is generated. For actuation experiment, syringe pump and laser interferometer were used for applying pressure and measuring the displacement. Several hundreds micro-scale actuation was observed. And, to demonstrate the feasibility of proposed actuation principle, in this research, a micro-gripper was developed using half-bellows structure.

• Clinics in Shoulder and Elbow
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• v.20 no.1
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• pp.46-48
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• 2017

There are many methods of making cement spacer in patients who require a two-staged operation for humeral head osteomyelitis. However, limitation of motion after the first surgery-due to inadequate size and insufficient intra-articular space for second surgery-remain to be an issue. To mitigate this issue, we made a cement spacer with the same size and shape of the patient humeral head. Four patients with humeral head osteomyelitis were enrolled in this study. To make the cement spacer, we used the Mimics program, and designed the molding box by a reverse engineering technique. We evaluated the range of motion and pain using a Constant score. The mean abduction was $50^{\circ}$($40^{\circ}-60^{\circ}$), forward flexion was $50^{\circ}$ ($30^{\circ}-70^{\circ}$), and average Constant score was 47.75 (44-52). Three-dimensional printed molding technique is one of the effective methods for humeral head osteomyelitis allowing for daily activities prior to the second surgery.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.67 no.3
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• pp.427-432
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• 2018

This paper uses a recursive least squares method to estimate the projectile motion trajectory of an object in real time. The equations of motion of the object are obtained considering the air resistance which occurs in the actual experiment environment. Because these equations consider air resistance, parameter estimation of nonlinear terms is required. However, nonlinear recursive least squares estimation is not suitable for estimating trajectory of projectile in that it requires a lot of computation time. Therefore, parameter estimation for real-time trajectory prediction is performed by recursive least square estimation after using Taylor series expansion to approximate nonlinear terms to polynomials. The proposed method is verified through experiments by using VICON Bonita motion capture system which can get three dimensional coordinates of projectile. The results indicate that proposed method is more accurate than linear Kalman filter method based on the equations of motion of projectile that does not consider air resistance.

• Journal of the Society of Naval Architects of Korea
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• v.40 no.5
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• pp.36-42
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• 2003

A CFD simulation technique has been developed to handle the unsteady body motion with large amplitude by use of overlapping multi-block grid system. The three-dimensional, viscous and incompressible flow around body is investigated by solving the Navier-Stokes equations, and the motion of body is represented by moving effect of the grid system. Composite grid system is employed in order to deal with both the body motion with large amplitude and the condition of numerical wave maker in convenience at the same time. The governing equations, Navier-Stokes (N-S) and continuity equations, are discretized by a finite volume method, in the framework of an O-H type boundary-fitted grid system (inner grid system including test model) and a rectangular grid system (outer grid system including simulation equipments for generation of wave environments). If this study, several flow configurations, such as an oscillating cylinder with large KC number, are studied in order to predict and evaluate the hydrodynamic forces. Furthermore, the motion simulation of a Series 60 model advancing in a uniform flow under the condition of enforced roll motion of angle 20$^{\circ}$ is performed in the developed numerical wave tank.

• Journal of Institute of Control, Robotics and Systems
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• v.12 no.11
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• pp.1074-1080
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• 2006

Motion capture systems are gaining popularity in entertainment, medicine, sports, education, and industry, with animation and gaming applications for entertainment taking the lead. A wide variety of systems are available for motion capture, but most of them are complicated and expensive. In the general class of optical motion capture, two or more optical sensors are needed to measure the 3D positions of the markers attached to the body. Recently, a 3D motion capture system using two Position Sensitive Detector (PSD) optical sensors was introduced to capture high-speed motion of an active infrared LED marker. The PSD-based system, however, is limited by a geometric calibration procedure for two PSD sensor modules that is too difficult for common customers. In this research, we have introduced a new system that used a single PSD sensor unit to obtain 3D positions of active IR LED-based markers. This new system is easy to calibrate and inexpensive.

• Structural Engineering and Mechanics
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• v.33 no.4
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• pp.407-428
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• 2009

The effects of the uniform and spatially varying ground motions on the stochastic response of fluid-structure interaction system during an earthquake are investigated by using the displacement based fluid finite elements in this paper. For this purpose, variable-number-nodes two-dimensional fluid finite elements based on the Lagrangian approach is programmed in FORTRAN language and incorporated into a general-purpose computer program SVEM, which is used for stochastic dynamic analysis of solid systems under spatially varying earthquake ground motion. The spatially varying earthquake ground motion model includes wave-passage, incoherence and site-response effects. The effect of the wave-passage is considered by using various wave velocities. The incoherence effect is examined by considering the Harichandran-Vanmarcke and Luco-Wong coherency models. Homogeneous medium and firm soil types are selected for considering the site-response effect where the foundation supports are constructed. A concrete gravity dam is selected for numerical example. The S16E component recorded at Pacoima dam during the San Fernando Earthquake in 1971 is used as a ground motion. Three different analysis cases are considered for spatially varying ground motion. Displacements, stresses and hydrodynamic pressures occurring on the upstream face of the dam are calculated for each case and compare with those of uniform ground motion. It is concluded that spatially varying earthquake ground motions have important effects on the stochastic response of fluid-structure interaction systems.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.43 no.1
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• pp.49-61
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• 2007

Otter boards in the trawl are the one of essential equipments for the net mouth to be spread to the horizontal direction. Its performance should be considered in the light of the spreading force to the drag and the stability of towing in the water. Up to the present, studies of the otter boards have focused mainly on the drag and lift force, but not on the stability of otter boards movement in 3 dimensional space. In this study, the otter board is regarded as a rigid body, which has six degrees of freedom motion in three dimensional coordinate system. The forces acting on the otter boards are the underwater weight, the resistance of drag and spread forces and the tension on the warps and otter pendants. The equations of forces were derived and substituted into the governing equations of 6 degrees of freedom motion, then the second order of differential equations to the otter boards were established. For the stable numerical integration of this system, Backward Euler one of implicit methods was used. From the results of the numerical calculation, graphic simulation was carried out. The simulations were conducted for 3 types of otter boards having same area with different aspect ratio(${\lambda}=0.5,\;1.0,\;1.5$). The tested gear was mid-water trawl and the towing speed was 4k't. The length of warp was 350m and all conditions were same to each otter board. The results of this study are like this; First, the otter boards of ${\lambda}=1.0$ showed the longest spread distance, and the ${\lambda}=0.5$ showed the shorted spread distance. Second, the otter boards of ${\lambda}=1.0$ and 1.5 showed the upright at the towing speed of 4k't, but the one of ${\lambda}=0.5$ heeled outside. Third, the yawing angles of three otter boards were similar after 100 seconds with the small oscillation. Fourth, it was revealed that the net height and width are affected by the characteristics of otter boards such as the lift coefficient.

• Korean Journal of Applied Biomechanics
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• v.18 no.4
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• pp.99-107
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• 2008

The aim of this study was to provide fundamental data in training to improve athletes' competitiveness through the comparative analysis of kinematic variables according to the types of stance. For this study, the subjects selected 4 Junior Weight lifters. Subjects performed two type(8-type and 11-type) Dead-lift and their performance was sampled at 60frame/sec. using four high-speed digital video cameras. After digitizing images from four cameras, the two-dimensional coordinates were used to produce three-dimensional coordinates of the 15 body segments(20 joint makers and 2 bar makers). And the results were as follows. 1. As for the time required for stances, 8-type motion was faster than 11-type motion. 2. As for the body-center shift in stances, 8-type motion was bigger than 11-type motion in back and forth motion shift, and 11-type motion was bigger than 8-type motion in right and left, up and down motion shift. 3. As for the speed of a body-center and a babel, 8-type motion was faster than 11-type motion. 4. As for the motion-trace of a babel in stances, 8-type motion was bigger than 11-type in back and forth, right and left motion and 11-type motion was bigger than 8-type in up and down motion. 5. As for the body-angles in stances, 8-type motion was bigger than 11-type in the stance angle, and 11-type motion is bigger than 8-type in the angles of a coxa, a knee and an ankle. As a result of the comparative analysis between 8-type and 11-type stance of Junior Weight lifters dead-lift, both were generally similar in variables, but 8-type motion was more stable than 11-type in aspects of time, speed, center shift, angle change.