• Title/Summary/Keyword: 점성 토크

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Friction Torque Analysis of a Hydraulic Motor-Load System using Proportional Control Valve (비례제어밸브를 이용한 유압모터 부하계의 마찰토크 해석)

  • Yu, Hwan-Shin;Park, Hyung-Bae
    • Journal of Advanced Navigation Technology
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    • v.14 no.5
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    • pp.760-766
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    • 2010
  • In this paper, The static friction torque and viscous friction torque including hydraulic motor-load system driven by hydraulic proportional control valve analysis. The basic experimental was performed toward characteristic in pressure and flow rate in hydraulic system energy. The variable of friction torque was experiment on brake pressure variable using pneumatic brake system. The analysis of nonlinear friction and linear friction was perform ed toward friction characteristic of hydraulic system.

Optimal Design of a Magnetorheological Haptic Gripper Reflecting Grasping Force and Rolling Moment from Telemanipulator (원격조작기의 악력과 회전모멘트를 고려한 MR 햅틱 그리퍼의 최적설계)

  • Nguyen, Quoc-Hung;Oh, Jong-Seok;Choi, Seung-Bok
    • Transactions of the Korean Society for Noise and Vibration Engineering
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    • v.22 no.5
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    • pp.459-467
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    • 2012
  • In this work, the configuration of a haptic gripper featuring magnetorheological(MR) brakes is proposed and an optimal design of the MR brakes for the haptic griper is performed considering the required braking torque, the uncontrollable torque(zero-field friction torque) and mass of the brakes. Several configurations of MR brake is proposed such as disc-type, serpentine-type and hybrid-type. After the configurations of the MR brakes are proposed, braking torque of the brakes is analyzed based on Bingham rheological model of the MR fluid. The zero-field friction torque of the MR brakes is also analyzed. An optimization procedure based on finite element analysis integrated with an optimization toolbox is developed for the MR brakes. The purpose of the optimal design is to find optimal geometric dimensions of the MR brake structure that can produce the required braking torque and minimize the mass of the MR brakes. In addition, the uncontrollable torque of the MR brakes is constrained to be much smaller than the required braking torque. Based on the developed optimization procedure, optimal solution of the proposed MR brakes are achieved and the best MR brake is determined. The working performance of the optimized MR brake is then investigated.

Study on the Viscous Roll Damping around Circular Cylinder Using Forced Oscillations (강제동요를 이용한 원형실린더 점성 롤댐핑 연구)

  • Yang, Seung-Ho
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.18 no.2
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    • pp.71-76
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    • 2017
  • The roll damping problem in the design of ships and offshore structures remains a challenge to many researchers due to the fluid viscosity and nonlinearity of the phenomenon itself. In this paper, the study on viscous roll damping of a circular cylinder was carried out using forced oscillations. The roll moment generated by forced oscillation using a torque sensor was measured for each forced oscillation period and compared with the empirical formula. Although the magnitude of the measured torque from the shear force was relatively small, the results were qualitatively similar to those obtained from the empirical formula, and showed good agreement with the quantitative results in some oscillation periods. In addition, the flow around the circular cylinder wall was observed closely through the PIV measurements. Owing to the fluid viscosity, a boundary layer was formed near the wall of the circular cylinder, and a minute wave was generated by periodical forced oscillations at the free surface through the PIV measurement. In this study, the suitability of the empirical formula for the roll moment caused by viscous roll damping was verified by model tests. The wave making phenomenon due to the fluid viscosity around the wall of a circular cylinder was testified by PIV measurements.

Analysis of Dynamics Characteristics for Friction Elements in Automatic Transmission (자동변속기 마찰요소의 동특성 해석)

  • 최영종;정우진;김성원
    • Transactions of the Korean Society of Automotive Engineers
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    • v.5 no.5
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    • pp.9-19
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    • 1997
  • In this paper, the modeling and analysis of dynamic characteristics has been carried out for friction clutches and brakes in an automatic transmission. From the operating oil pressure generated by the valve-body, time delay by check valve and the movement of piston has been examined. Also torque capacity and torque transferred at the clutch is studied. Heat capacity and temperature distribution at the reaction plate of clutch are codeled by time-dependent, nonhomogeneous partial differential equation, and brake torque, brake time, and the amount of heat generated are investigated. It is found that the time delay at the check valve is very short but dominant at the spool.

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Computation of Four Quadrant Performance for a Marine Propeller in Open Water (박용 프로펠러의 4상한 단독성능 계산)

  • Hyoung-Tae Kim;Jeong-Jung Kim
    • Journal of the Society of Naval Architects of Korea
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    • v.38 no.4
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    • pp.1-10
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    • 2001
  • A numerical solution method of the incompressible Reynolds-Averaged Navier-Stokes equations is applied for calculating turbulent flows and performances of a marine propeller in open-water, four-quadrant conditions. Computed propeller flows of the model propeller P4381, for which the experimental data of the open-water performances exist, reveal complex viscous-flow characteristics including three-dimensional flow separations in various off-design conditions and also computed propeller thrusts and torques agree quite well with experimental data except some cases for which severe propeller cavitations occurred in the experiment.

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A Study on Rheology Properties of High Performance Wet-mix Shotcrete (고성능 습식 숏크리트의 레올로지에 관한 기초연구)

  • Choi, Sung-Yong;Yun, Kyong-Ku;Kim, Jin-Woung;Kim, Yong-Bin
    • Journal of the Korean Society of Hazard Mitigation
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    • v.10 no.4
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    • pp.25-32
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    • 2010
  • High performance shotcrete has been recently researched partly as a result of high consensus on high strength and durability. However, they are very initial step compared from the advanced countries. For instance, they has been mainly on high strength or durability without any consideration on pumpability and shootability which are very crucial on workability. The purpose of this dissertation was to make a high performance wet-mix shotcrete (high workability) which would solve the general problems of wet-mix process in Korea. For this, the main experimental variables were selected to be silica fume(0.0, 4.5, 9%), air entrained agent(0.0, 0.005%). Rheology with IBB rheometer was measured for evaluating pumpability and shootability as well as pump pressure, rebound rate and build-up thickness. The conclusions from a series of experiments were as follow: The results of analyzing the effects of AE agent and silica fume on rheology indicated that AE agent reduced both of flow resistance(G) and torque viscosity(H) and silica fume increased flow resistance (G) and reduced torque viscosity(H). An increase in the value of torque viscosity(H) produces an increase in the requried pumping pressure. These result indicated that the reduction of torque would work better at improving pumpability. And an increase flow resistance(G) improved shootability(increase build-up thickness and reduce rebound).

Compliance Control of a Direct-Drive Manipulator using Phase-Difference of Ultrasonic Motor (초음파 모터의 위상차를 이용한 직접구동 매니퓰레이터의 컴플라이언스 제어)

  • 오금곤;김대현;김영동;김재민
    • The Transactions of the Korean Institute of Power Electronics
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    • v.4 no.6
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    • pp.608-615
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    • 1999
  • In this paper, the compliance control method was propoSL'Cl and the phase-difference operating principle of an u ultrasonic motor described. The compliance control can he implementtcD with spring/damper properties of the r musculo-skeletal system of the actual limb in controlling its net configuration and movement. The proposed p phase-difference driving scheme is verifitcD through the computer simulation. Also, $textsc{k}$rformance of the proposed c control method of a two-link direct-drive manipulator are examinLD by the experimental results with resptc'Ct to s spring/ damper properties.

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A Study on High-output MR (Magneto-rheological) Brake for Tension Control (장력제어용 고출력 MR 브레이크)

  • Park, Jung-Ho;Kim, Jin-Gyu;Youn, Dong-Won;Ham, Sang-Yong;Noh, Jong-Ho;Yoo, Jin-San
    • Proceedings of the KSME Conference
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    • 2007.05a
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    • pp.1422-1427
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    • 2007
  • MR fluid is a suspension of micrometer-sized magnetizable particles in silicon oil and a functional fluid whose apparent viscosity can be controlled by the applied magnetic field strength. In this paper, a rotary brake using MR fluid called MR brake for tension control of precision machinery such as roll-to-roll printing machinery is presented. First, to obtain the higher performance than conventional powder brake, a MR brake with a modified rotor shape is newly designed and analyzed using FEM. Second, the prototype of MR brake is fabricated with the optimized structural parameters and an experimental apparatus is constructed. Then, basic characteristics of the MR brake are investigated with the different MR fluids. Finally, the validity of the developed MR brake is verified through the comparison with the conventional powder brake.

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A Study on Torque Transmission Using Electro-Rheological Fluid (전기점성 유체를 이용한 동력전달 장치에 관한 연구)

  • 주동우;이은준;박명관
    • Journal of the Korean Society for Precision Engineering
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    • v.15 no.10
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    • pp.81-87
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    • 1998
  • This paper provides an investigation of torque transmission system using ERF (Electro-Rheological Fluid). The torque transmission system using ERF is a new conception device because an apparent viscosity of ERF can be changed by applying an electric field, We use the coaxial cylinder type in which the ERF fills the annular space between a pair of coaxial cylindrical electrodes and experiment results show that the measured torque was increased with the increase of the electric field. These are analyzed to provide guidelines to assist in the development of practical ER devices.

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Elasticity and Viscosity Control of an Ultrasonic Motor by a Phase Difference Control (초음파 모터의 위상차 조절에 의한 점탄성 제어)

  • 우수용;이권현;오금곤;정헌상;김영동
    • The Proceedings of the Korean Institute of Illuminating and Electrical Installation Engineers
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    • v.11 no.5
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    • pp.86-92
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    • 1997
  • An ultrasonic motor(USM) has good characteristics such as compact size, silent motion, high speed responce, low speed and high torque. The USM is driven by 2-phase AC electricity. The control parameters of USM are voltage, phase, and frequency of input powers, etc. In this paper, the fine elasticity and viscosity control with no force feedback can be implemented by a phase difference parameter. Experiment results show the change of torque with regard to elasticity and viscosity. Therefore the USM can be used as a micro-actuator in the automation field of the installation.

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