• 한국의학물리학회지:의학물리
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• 제27권3호
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• pp.117-124
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• 2016

Intrafractional motion of patients, such as respiratory motion during radiation treatment, is an important issue in image-guided radiotherapy. The accuracy of the radiation treatment decreases as the motion range increases. We developed a control system for a robotic patient immobilization system that enables to reduce the range of tumor motion by compensating the tumor motion. Fusion technology, combining robotics and mechatronics, was developed and applied in this study. First, a small-sized prototype was established for use with an industrial miniature robot. The patient immobilization system consisted of an optical tracking system, a robotic couch, a robot controller, and a control program for managing the system components. A multi speed and position control mechanism with three degrees of freedom was designed. The parameters for operating the control system, such as the coordinate transformation parameters and calibration parameters, were measured and evaluated for a prototype device. After developing the control system using the prototype device, a feasibility test on a full-scale patient immobilization system was performed, using a large industrial robot and couch. The performances of both the prototype device and the realistic device were evaluated using a respiratory motion phantom, for several patterns of respiratory motion. For all patterns of motion, the root mean squared error of the corresponding detected motion trajectories were reduced by more than 40%. The proposed system improves the accuracy of the radiation dose delivered to the target and reduces the unwanted irradiation of normal tissue.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2007년도 춘계학술대회B
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• pp.3015-3020
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• 2007

An experimental study of the dynamic characteristics of the free rising oblate spherical bubble is investigated. As noted by Saffman, the characteristics of the spiral motion are defined with parameters of the spiral frequency, spiral radius, and rising velocity. High speed camera recorded every detail information of free rising bubble. The spiral number, the bubble rise velocity, and the angular velocities were measured for the bubble size between 1.0mm to 20.0mm in diameter. In order to make clear trajectory, we employed the Fast Fourier Transformation for the normal digital camera data to synchronize with the high speed camera data. It was found that the spiral number suggested here was monotonically decreased as the bubble size increases. The present observation, however tells us that previous Saffman's formulation shows a good agreement with the trend, but over estimated spiral number. Therefore, it is recommended that Saffman's theoretical study is needed to be improved.

• Structural Engineering and Mechanics
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• 제66권5호
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• pp.595-608
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• 2018

This paper deals with the lateral - torsional motion of bridges provided with external cables acting as dampers under the action of horizontal dynamic loads or of walking human crowd loads. A three dimensional analysis is performed for the solution of the bridge models. The theoretical formulation is based on a continuum approach, which has been widely used in the literature to analyze bridges. The resulting equations of the uncoupled motion are solved using the Laplace Transformation, while the case of the coupled motion is solved through the use of the potential energy. Finally, characteristic examples are presented and useful results are obtained.

• 한국해양공학회:학술대회논문집
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• 한국해양공학회 2001년도 추계학술대회 논문집
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• pp.164-168
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• 2001

The motion of a ship advancing in regular waves is analyzed in the time-domain using the convolution integral of the radiation forces. The memory effect functions and infinite frequency added masses are obtained from the solution of the three dimensional improved Green integral equation in the frequency domain by making use of the Fourier transformation. The ship motions in regular waves have been calculated by both the time and frequency domain methods. It has been shown that they agree very well with each other. The present time-domain method can be used to predict the time histories of unsteady motions in irregular waves. It can also be used to calculate the hydrostatic and Froude-Krylov forces over the instantaneous wetted surface of the ship hull to predict large ship motions, in a practical sense, advancing in large amplitude waves.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1990년도 한국자동제어학술회의논문집(국제학술편); KOEX, Seoul; 26-27 Oct. 1990
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• pp.1027-1031
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• 1990

In this paper, we propose a model-based method of estimating the velocity of a moving object from a series of images. The proposed method utilizes Kalman filtering technique. Assuming that the motion is described by an affine transformation, we construct a discrete-time state variable model of the motion based on the dynamic motion imagery modeling technique proposed by Schalkoff. Using this state variable model, we derive a Kalman filter algorithm. Some simulation results are presented to show that the proposed Kalman filter algorithm is superior to a simple least square method without a model.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 1999년도 추계종합학술대회 논문집
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• pp.621-624
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• 1999

This paper describes a distance estimation method of object's motion in soccer image sequence by tracking field features. And we quantitatively evaluate the estimation accuracy We suppose that the input image sequence is taken with a camera on static axis and includes only zooming and panning transformation between frames. Adaptive template matching is adopted for non-rigid object tracking. For background compensation, feature templates selected from reference frame image are matched in following frames and the matched feature point pairs are used in computing Affine motion parameters. A perspective displacement field model is used for estimating the real distance between two position on Input Image. To quantitatively evaluate the accuracy of the estimation, we synthesized a 3 dimensional virtual stadium with graphic tools and experimented on the synthesized 2 dimensional image sequences. The experiment shows that the average of the error between the actual moving distance and the estimated distance is 1.84%.

• 한국공작기계학회:학술대회논문집
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• 한국공작기계학회 2000년도 춘계학술대회논문집 - 한국공작기계학회
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• pp.367-372
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• 2000

Accuracy of a machined component is determined by the relative motion between the cutting tool and the workpiece. One of the important factors which affects the accuracy of this relative motion is the geometric error of machine tools. In this study, geometric error is modeled using form shaping motion of machine tool, where a form shaping function is derived from the homogeneous transformation matrix. Geometric errors are measured by laser interferometer. After that, the local positioning error can be estimated from the form shaping model and geometric error data base. From this information, we can remodel the part by shifting the design surface to the amount of positional error. By generating tool path to the redesigned surface, we can reduce the machining error.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1998년도 추계학술대회 논문집 학회본부 B
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• pp.552-554
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• 1998

This paper deals with the gait generation of IWR-III using a kick action to have a walking pattern like human. For this, trajectory planning with the consideration of kick action is done in each walking step, and the coordinate transformation is done for simplifying the kinematics. Balancing motion is analyzed by FDM during the walking, By combining 4-types of pre-defined steps, multi-step walking is done. Using numerical simulator, dynamic analysis, ZMP analysis and system stability is confirmed. Walking motion is visualized by 3D- graphic simulator. As a result, trunk ahead motion effect and impactless smooth walking is implemented by experiment. Finally walking with kick action is implemented the IWR-III system.

• Coupled systems mechanics
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• 제6권4호
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• pp.377-398
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• 2017

The present paper deals with the influence of the inclination of cables' system on the decrease of the lateral-torsional motion because of dynamic loadings. For this goal, a mathematical model is proposed. A 3-D analysis is performed for the solution of the bridge model. The theoretical formulation is based on a continuum approach, which has been widely used in the literature to analyze such bridges. The resulting uncoupled equations of motion are solved using the Laplace Transformation, while the case of the coupled motion is solved through the use of the potential energy. Finally, characteristic examples are presented and useful results are obtained.

• 한국운동역학회지
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• 제15권1호
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• pp.111-125
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• 2005

This study was intended to assist athletes in having a technical understanding of the Yega motion and provide basic material for improving their competitive ability by analyzing the kinematic variable of the Yega motion during the competition of the uneven parallel bar of female gymnastics. For this purpose, the game of female gymnastics participating in the uneven parallel bar game was personally videotaped using the DLT(direct linear transformation) method. An attempt was made to make a comparative analysis of the Yega motion by dividing the final first to third places into the upper group('A' group) and the sixth to eighth places into the lower group('B' group). Based on the results of actual analysis on the scenes of actual game, the following conclusion was concluded: 1. Athletes in the 'A' group showed the shorter required time on the flight phase(P3) than counterparts in the 'B' group. 2. Athletes in the 'A' group showed the little width in the horizontal displacement of the center of gravity than counterparts in the 'B' group. But athletes in the 'A' group exhibited the somewhat greater relative vertical height of the center of the body. 3. Athletes in the 'A' group showed the greater resultant velocity at the lowest point of the center of the body(E2) and at the point in time of release(E3) compared to counterparts in the 'B' group.