• Aerospace Engineering and Technology
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• v.12 no.2
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• pp.1-6
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• 2013

A LEO satellite transmits recorded images to a ground station using an X-band antenna during contact. The X-band antenna points to the ground station according to a TPF (tracking parameter file) during communication time. A TPF generation software generates azimuth and elevation profile which make the antenna point to the ground station using satellite orbit and attitude information and mission information including recording and downlink operation. When the satellite passes above the ground station, azimuth velocity increases rapidly so that jitter may occur if the azimuth velocity is in specific range. In case of realtime mission in which the satellite perform recording and downlink simultaneously, azimuth velocity must be lower than specific value to prevent image blur due to jitter effect. The method to point one virtual ground station has limitation of azimuth velocity reduction. In this paper, we propose the azimuth fixing method to reduce azimuth velocity of X-band antenna. The experimental results show that azimuth velocity of the X-band antenna is remarkably reduced using proposed method.

• Journal of The Korean Society of Integrative Medicine
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• v.3 no.4
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• pp.37-42
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• 2015

Purpose: This study was conducted to test the impact of The Dynamic Visual-Motor integration training has effect on the visual perception reaction velocity. Dynavision were used to measure data from the participating 24 students(K college). Method : The participants were the 24 students of 'K' College in Busan in there twenties. They were divided into the The Dynamic Visual-Motor integration training group and the control group. To know if the Dynamic Visual-Motor integration training has effect on the visual perception reaction velocity, the Dynamic Visual-Motor integration training was implemented triweekly for 4 weeks. In Dynamic Visual-Motor integration training the ball should be grasped with one hand and threw by an arm. Only the balls threw beyond the objective point were counted. The visual perception reaction velocity and the number of response were measured before and after experiment by Dynavision. Result : Firstly, the visual perception reaction velocity was increased in Dynamic Visual-Motor integration training group compared with control group. Secondly, the number of response was also increased in Dynamic Visual-Motor integration training group compared with control group. Conclusion : As a result of The Dynamic Visual-Motor integration training has an effect on the visual perception reaction velocity and the number of response. The Dynamic Visual-Motor integration training seems to be effective for cerebral apoplexy patient who has visual perceptional disability or cerebral palsy child in training for visual perceptional development or daily living activities development. Study participated by more detailed and practical patients in hospital is needed.

• Journal of Korea Water Resources Association
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• v.41 no.6
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• pp.575-585
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• 2008

It is essential to obtain accurate and highly reliable streamflow data for water resources planning, evaluation and management as well as design of hydraulic structures. A new discharge computation method proposed in this research uses Chiu's velocity distribution and estimation of maximum velocity. This method shows acceptable channel discharges comparing these by the exiting velocity-area method. When velocity-area method is used, it is required to observe velocities at every specified point and vertical line using a velocity meter like Price-AA. If the method proposed in this research, is used, however it is not necessary to observe all point velocities needed in the velocity-area method. But this method can not be applied for the cases of very complex and strongly asymmetric channel cross-sections because Chiu's velocity distribution using entropy concept may be quite biased from that of natural rivers.

• Journal of Korea Society of Industrial Information Systems
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• v.21 no.1
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• pp.7-15
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• 2016

Ocean wave parameters are important for safety and efficiency of operation and routing of marine traffic. In this paper, by using X-band marine radar, we try to develop an effective algorithm for collecting ocean surface information such as current velocity, wave parameters. Specifically, by exploiting iterative refinement flow instead of using fixed control schemes, an effective algorithm is designed in such a way that it can not only compute efficiently the optimized current velocity but also introduce new cost function in an optimized way. Experimental results show that the proposed algorithm is very effective in retrieving the wave information compared to the conventional algorithms.

• International Journal of Contents
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• v.3 no.4
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• pp.22-25
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• 2007

This paper presents a technology of information data fusion between radar and ELINT electronic intelligence system. adar get the information of the range, direction and velocity of targets, and ELINT system get the information of the direction and angular velocity of the same targets at the same place and at the same time. Since we have some common information data of targets from radar and ELINT system, we can find the target on radar is same or not on ELINT system using the information data fusions. If the target on the radar is verified with the same target on ELINT system, we get more information of the target. e can analysis and identify the target exactly and reduce an ambiguity error of unknown targets.

• Transactions of the Korean Society of Automotive Engineers
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• v.19 no.1
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• pp.51-57
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• 2011

Information of the lateral velocity and the sideslip angle in a vehicle is very useful in many active vehicle safety applications such as yaw stability control and rollover prevention. Because cost-effective sensors to measure the lateral velocity and the sideslip angle are not available, reliable algorithms to estimation them are necessary. In this paper, a sliding mode observer is designed to estimate the lateral velocity. The side slip angle is estimated using the recursive least square with the disturbance observer and the pseudo integral. The estimated parameters from the combined estimation method are updated recursively to minimize the discrepancy between the model and the physical plant, and any possible effects caused by disturbances. The performance of the proposed monitoring system is evaluated through simulations and experiments.

• Journal of Advanced Marine Engineering and Technology
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• v.15 no.1
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• pp.71-74
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• 1991

Uncertainty analyses accompanied by the measurement of the velocity vectors in 3-D cavity flows are carried out. Twenty-one elemental errors are esimated or calculated according to the ANIS/ASME uncertainty analysis manual. Error components associater with the PIV(Particle Imaging Velocimetry) are reasonably small and the errors caused by the flow characteristics are fairly large, which confirm the reliability of the PIV measurement and also give good information to the planning phase of the experiment by discriminating the most critical parameter. The present study reveals that vector length expressed by pixels is the most influential. Calculated relative uncertainty for the all experimental conditions is ranging about 5-10% in terms of the representative velocity 0.5U. U is here the belt velocity on the cavity apparatus. Approximating equations to show the relative rss uncertainties are given and graphic representations are followed for the easier understanding of the uncertainty, existing in the velocity profiles of the cavity flow.

• Journal of the Korean Institute of Telematics and Electronics S
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• v.34S no.11
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• pp.63-72
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• 1997

The design and implementation of a drive wheel position, orientation, and velocity feedback control algorithm for a differential-drive mobile robot is described here. A new concept, the most significant error, is introduced as the control design objective. Drive wheel position, orientation, and velocity feedback control directly minimize the most siginificant error by coordinating the motion of the two drive wheels. The drive wheel position, orientation, and velocity feedback control algorithm is analyzed and experiments are conducted to evaluate its performance. The experimental results are shown that drive wheel position, orientation and velocity feedback control algorithm yields substantially smaller position and orientation errors than those of conventional methods.

• Journal of Mechanical Science and Technology
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• v.15 no.12
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• pp.1845-1852
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• 2001

This paper deals with the experiment to obtain quantitative information about conditions of the interface between a water drop and surrounding oil. Velocity distributions in very close region of the interface are measured by introducing a new illumination technique and a telecentric lens. It enables precise measurements of velocity distributions in the close region to the interface. Although the measured velocity distributions exhibit strong influence from the solid wall of an experimental tube, the coincidence of inner and outside velocities on the interface is clearly confirmed for the clean interface. The shearing stresses on the interface, which are proportional to the velocity gradient normal to the interface, clearly show conditions of contaminated interface, which can be divided into two parts. From front stagnation point to somewhere near a separation point, the distribution of shearing stresses is well coincide with that of the Hadamard's analytical solution, while the distribution on the latter part of the interface sows quite different feature, which is supposed to be strongly influenced by contamination of the surface.

• Journal of Advanced Marine Engineering and Technology
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• v.31 no.5
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• pp.531-542
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• 2007

Simultaneous measurement technique for temperature and velocity fields near a heated solid body has been constructed. The measurement system consists of a 3-late CCD color camera, a color image grabber, a 1ighting system, a host computer and a software for the whole quantification process. Thermo Chromic Liquid Crystals (TCLC) was used as temperature sensors. A neural network was used to get a calibration curve between the temperature and the color change of the TCLC in order to enhance the dynamic range of temperature measurement. The velocity field measurement was attained by the use of the fray-level images taken for the flow field, and by introducing the cross-correlation technique. The temperature and the velocity fields of the forced and the natural convective flows neat the surface of a cartridge heater were measured simultaneously with the constructed measurement system.