• Title/Summary/Keyword: Moving velocity

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Improvement of Rectangle Sedimentation basin using the Moving Baffle (이동식 정류장치를 이용한 횡류식 침전지 침전효율 개선 연구)

  • Cho, Young-Man
    • Journal of Korean Society of Environmental Engineers
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    • v.27 no.7
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    • pp.726-731
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    • 2005
  • Sedimentation is treated as the most important unit process in waterworks, and plays great role on turbidity removal efficiency. Rectangle sedimentation basin is the most widely accepted sedimentation process. But it has some problems with short-circuit flow and density flow caused by temperature and influent turbidity variation. To solve these problems, installation of rectification wall was suggested, but not generally fully accepted in field. Because hole of rectification wall cause jet flow. In this research, use of moving baffle was investigated. Moving baffle was designed to induce uniform velocity at every section of water flow. The baffle walls was made from soft fiber materials. The baffle walls with flow of sedimentation basin moves at same speed. It is like that it controls density flow and short-circuit flow and induce uniform velocity at every section of water flow in sedimentation basin. When moving baffle was operated retention time of sedimentation basin was extended to 1 hours. When it talked again and the effluent time of highest concentration of the chlorine ion from 100 minutes was extended to 160 minutes. Turbidity removal efficiency was tested with different operation modes(continuous and batch) with influent turbidity and retention time. It was revealed that turbidity removal efficiency carl be improved up to 36%(continuous mode) and 58%(batch mode) respectively. Consequently if moving baffle introduces in Rectangle sedimentation basin, it forecasts that the turbidity improvement above 30% will be possible.

INFLUENCE OF THERMAL CONDUCTIVITY AND VARIABLE VISCOSITY ON THE FLOW OF A MICROPOLAR FLUID PAST A CONTINUOUSLY MOVING PLATE WITH SUCTION OR INJECTION

  • Salem, A.M.;Odda, S.N.
    • Journal of the Korean Society for Industrial and Applied Mathematics
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    • v.9 no.2
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    • pp.45-53
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    • 2005
  • This paper investigates the influence of thermal conductivity and variable viscosity on the problem of micropolar fluid in the presence of suction or injection. The fluid viscosity is assumed to vary as an exponential function of temperature and the thermal conductivity is assumed to vary as a linear function of temperature. The governing fundamental equations are approximated by a system of nonlinear ordinary differential equations and are solved numerically by using shooting method. Numerical results are presented for the distribution of velocity, microrotation and temperature profiles within the boundary layer. Results for the details of the velocity, angular velocity and temperature fields as well as the friction coefficient, couple stress and heat transfer rate have been presented.

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Time optimal trajectory planning for a robot system Under torque and impulse constraints.

  • Cho, Bang-Hyun;Lee, Jang-Myung
    • 제어로봇시스템학회:학술대회논문집
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    • 2004.08a
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    • pp.1402-1407
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    • 2004
  • Moving a fragile object from an initial point to a goal location in minimum time without damage is pursued in this paper. In order to achieve the goal, first of all, the range of maximum acceleration and velocity are specified, which the manipulator can generate dynamically on the path that is planned a priori considering the geometrical constraints. Later, considering the impulsive force constraint of the object, the range of maximum acceleration and velocity are going to be obtained to keep the object safe while the manipulator is carrying it along the curved path. Finally, a time-optimal trajectory is planned within the maximum allowable range of the acceleration and velocity. This time optimal trajectory planning can be applied for real applications and is suitable for not only a continuous path but also a discrete path.

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Modeling for Tension Control of the Bio-Wrap Winding Machine (생분해성 랩 와인딩 기계의 장력제어를 위한 모델링)

  • Park W.C.;Kim H.S.;Kim D.I.;Yang S.M.;Kee C.D.
    • Proceedings of the Korean Society of Precision Engineering Conference
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    • 2005.06a
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    • pp.1901-1905
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    • 2005
  • This Paper describes the mathematical modeling and control of the tension and the speed of moving Bio-wrap in a wrap winding machine. In winding process, important control specifications include the regulation of wrap tension and velocity. In this research, a tension and velocity model has been developed for winding processes. A prototype winding system has been constructed, and the controller has been implemented in a real time PC-based environment. The tension control system is modeled a MIMO of the two-input and four-output system. The performance of the modeled system has been evaluated via simulation using MATLAB and experiments.

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The Flow Characteristics Around Airfoil Moving Reciprocally in a Channel (수로 내에서 왕복 운동하는 에어포일 주위의 유동특성)

  • Ro, Ki-Deok;Kim, Kwang-Seok;Kim, Jong-Hyeon
    • Transactions of the Korean Society of Mechanical Engineers B
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    • v.32 no.7
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    • pp.536-541
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    • 2008
  • The Flow characteristics of a ship's propulsion mechanism of Weis-Fogh type, in which a airfoil(NACA0010) moves reciprocally in a channel, were investigated by the PIV. Velocity vectors and velocity profiles around the operating and stationary wings were observed at opening angles of ${\alpha}=15^{\circ}$ and $30^{\circ}$, velocity ratios of $V/U=0.5{\sim}1.5$ and Reynolds number of $Re=0.52{\times}104{\sim}1.0{\times}104$. As the results the fluid between wing and wall was inhaled in the opening stage and was jet in the closing stage. The wing in the translating stage accelerated the fluid in the channel. And the flow fields of this propulsion mechanism were unsteady and complex, but those were clarified by flow visualization using the PIV.

Simultaneous measurement of velocity fields of wind-blown sand and surrounding wind in an atmospheric boundary layer

  • Zhang W.;Wang Y.;Lee S. J.
    • 한국가시화정보학회:학술대회논문집
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    • 2005.12a
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    • pp.11-16
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    • 2005
  • Saltation is the most important mechanism of wind-blown sand transport. Till now the interaction between wind and sand has not been fully understood. In this study the saltation of sand sample taken from Taklimakan desert was tested in a simulated atmospheric boundary layer. The captured particle images containing both the tracers for wind and saltating sand, were separated by a digital phase mask technique. Both PIV and PTV methods were employed to extract the velocity fields of wind and the dispersed sand particles, respectively. The mean streamwise wind velocity field and turbulent statistics with and without sand transportation were compared, revealing the effect of the moving sand on the wind field. This study is helpful to understand the interaction between wind and blown sand (in saltation), and provide reliable experimental data fur evaluating numerical models.

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Collision Avoidance for UAV using Potential Field based on Relative Velocity of Obstacles (장애물의 상대속도를 반영한 포텐셜필드 기반 무인항공기 충돌회피)

  • Ahn, Seung-gyu;Lee, Dongjin
    • Journal of the Korean Society for Aviation and Aeronautics
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    • v.26 no.2
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    • pp.47-53
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    • 2018
  • In this paper, we investigate a collision avoidance algorithm for unmanned aerial vehicles using potential field based on the relative velocity of obstacles. The potential field consists of the attraction force and the repulsive force that are generated for the target and the obstacles. And the field can be classified into the attractive potential field generated by the target and the repulsive potential field generated by the obstacle, respectively. In this study, we construct an attractive potential field as a function of the distance between the UAV and the target position. On the other hand, a repulsive potential field is created by a function of distance and the relative velocity of the obstacle with respect to the UAV. The proposed potential field based collision avoidance algorithm is evaluate through simulations.

Nonlinear Friction Compensator Design for Mechatronics Servo Systems Using Neural Network

  • Chung, Dae-won;Nobuhiro Kyra;Hiromu Gotanda
    • Transactions on Control, Automation and Systems Engineering
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    • v.3 no.2
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    • pp.111-116
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    • 2001
  • A neural network compensator for stick-slip friction phenomena in meashartonics servo systems is practically proposed to supplement the traditionally available position and velocity control loops for precise motion control. The neural network compensa-tor plays the role of canceling the effect of nonlinear slipping friction force. It works robustly and effectively in a real control system. This enables the mechatronics servo systems to provide more precise control in the digital computer. It was confirmed that the con-trol accuracy is improved near zero velocity and points of changing the moving direction through numerical simulation. However, asymptotic property on the steady state error of the normal operation points is guaranteed by the integral term of traditional velocity loop controller.

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Time-optimal Trajectory Planning for a Robot System under Torque and Impulse Constraints

  • Cho, Bang-Hyun;Choi, Byoung-Suk;Lee, Jang-Myung
    • International Journal of Control, Automation, and Systems
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    • v.4 no.1
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    • pp.10-16
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    • 2006
  • In this paper, moving a fragile object from an initial point to a specific location in the minimum time without damage is studied. In order to achieve this goal, initially, the maximum acceleration and velocity ranges are specified. These ranges can be dynamically generate on the planned path by the manipulator. The path can be altered by considering the geometrical constraints. Later, considering the impulsive force constraint on the object, the range of maximum acceleration and velocity are obtained to preserve object safety while the manipulator is carrying it along the curved path. Finally, a time-optimal trajectory is planned within the maximum allowable range of acceleration and velocity. This time-optimal trajectory planning can be applied to real applications and is suitable for both continuous and discrete paths.

Heavy-Weight Component First Placement Algorithm for Minimizing Assembly Time of Printed Circuit Board Component Placement Machine

  • Lee, Sang-Un
    • Journal of the Korea Society of Computer and Information
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    • v.21 no.3
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    • pp.57-64
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    • 2016
  • This paper deals with the PCB assembly time minimization problem that the PAP (pick-and-placement) machine pickup the K-weighted group of N-components, loading, and place into the PCB placement location. This problem considers the rotational turret velocity according to component weight group and moving velocity of distance in two component placement locations in PCB. This paper suggest heavy-weight component group first pick-and-place strategy that the feeder sequence fit to the placement location Hamiltonean cycle sequence. This algorithm applies the quadratic assignment problem (QAP) that considers feeder sequence and location sequence, and the linear assignment problem (LAP) that considers only feeder sequence. The proposed algorithm shorten the assembly time than iATMA for QAP, and same result as iATMA that shorten the assembly time than ATMA.