• Transactions of the Korean Society of Mechanical Engineers A
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• v.30 no.9 s.252
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• pp.1025-1033
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• 2006

This paper describes the levitation mechanism using magnetic wheel for a maglev planar transportation system. Rotation of the magnetic wheel where the permanent magnet array is embedded produces the time varying traveling magnetic flux density and the generated magnetic flux density creates the induced levitation force and drag force with the conductor. Because the net drag force is zero, magnetic wheel can only generate the levitation force. Thus, it always guarantees the stability in levitation direction and it does not disturb other directional motion. In this paper, levitation principle of the magnetic wheel is analyzed using distributed field approach and dynamic characteristics of the levitation in the magnetic wheel system are estimated. The feasibility of the proposed levitation mechanism is verified through the several experimental works.

• Journal of Soil and Groundwater Environment
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• v.7 no.3
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• pp.85-94
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• 2002

Overall objective of this study was to evaluate the electrochemical characteristics of fine soils during the electrokinetic(EK) remediation. Zeta potential of kaolinite as a function of solution pH and surfactant concentration was investigated to make a relationship with electroosmotic flow direction and rate. During the EK experiments, pH of pore solution, electroosmotic permeability($k_e$), electric conductivity($\delta_e$) and voltage distribution was measured, respectively, The point of zero charge(PZC) of kaolinite was estimated to be about 4.2 and the zeta potential of kaolinite above PZC was more negative as solution pH increased. Sorption of surfactants on the kaolinite altered the zeta potential of kaolinite. resulting from the variation of electrochemical characteristics of kaolinite surface. hs the EK experiment progressed, low pH was predominant over most of the kaolinite specimen and thus resulted in very low mass and charge flow. The $k_e$ and $\delta_e$ was also affected by the variation of voltage drop across the EK column with time. Results from this study implied that zeta potential of kaolinite affected by the pH variation of pore solution and voltage distribution in soil column played important role in the determination of mass and charge flow during EK process. It was also suggested that pH adjustment or addition of suitable sorbates could alter the electrochemical characteristics of soil surface and thus maintain high mass and charge flow rate with time.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.25 no.5
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• pp.741-749
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• 2001

An inhomogeneous hyperbolic electric field is established among two-dimensional quadrupole electrodes to which an ac voltage is applied. Conditions under which charged particles are focused into a narrow axis region of the plug laminar flow are discussed. The aerodynamic forces influence the behavior of the charged particles in the quadrupole electric field. We derived the dimensionless equations of motion of a charged particle in the alternating quadrupole electric field, and discussed particle trajectories and focusing performance in terms of two dimensionless parameters, which are functions of particle size, operating pressure, and the amplitude and frequency of applied AC voltage, with the results of numerical simulations and experiments.

• Journal of the Korean Society for Precision Engineering
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• v.27 no.7
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• pp.109-116
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• 2010

The magnet wheel which generates on its interfacing conductive part a repulsive force and a traction torque by rotation of permanent magnets is used to manipulate the conductive plate without mechanical contact. Here, the air-gap magnetic field of the magnet wheel is shielded partially to convert the traction torque into a linear thrust force. Although a magnitude of the thrust force is constant under the fixed open region, we can change the direction of force by varying a position of the shield sheet. So, the spatial position of conductive plate is controlled by not the force magnitude from each magnet wheel but the open position of shield sheet. This paper discusses non-contact conveyance system of the conductive plate using electromagnetic forces from multiple magnet wheels.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.11
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• pp.794-801
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• 2017

When a radial wheel is placed so as to partially overlap a conductive plate and rotated, a lift force is generated on the wheel, a thrust force along the edge, and a lateral force which tends to reduce the overlap region. When several of these wheels are combined, it is possible to realize a system in which the stability of the remaining axes is ensured, except in the traveling direction. To validate the overall characteristics of the multi-wheel system, we propose a transfer system levitated magnetically using radial electrodynamic wheels. The proposed system is floated and propelled by four wheels and arranged in a structure that allows the thrusts generated by the front and rear wheels to offset each other. The dynamic stability of the wheel and the effect of the pole number on the three-axial forces are analyzed by the finite element method. At this time, the thrust and levitation force are strongly coupled, and the only factor affecting them is the wheel rotation speed. Therefore, in order to control these two forces independently, we make use of the fact that the ratio of the thrust to the levitation force is proportional to the velocity and is independent of the size of the gap. The in-plane and out-of-plane motion control of the system is achieved by this control method and compared with the simulation results. The experimental results show that the coupled degrees of freedom can be effectively controlled by the wheel speed alone.

• Journal of the Korean Society for Precision Engineering
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• v.26 no.9
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• pp.72-80
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• 2009

When the magnet wheel rotates over a conducting plate, it generates the traction torque as well as the repulsive force on the conducting plate. Partially-cut traction torque results in the linear force into the tangential direction. To cut the traction torque, the concept of magnetic shield is introduced. The direction change of the linear force is realized varying the shielded area of magnetic field. That is, the tangential direction of non-shielded open area becomes the direction of the linear thrust force. Specially a shape of permanent magnets composing the magnet wheel leads to various pattern of magnetic forces. So, to enlarge the resulting force density and compensate its servo property a few simulations are performed under various conditions such as repeated pattern, pole number, radial width of permanent magnets, including shape of open area. The theoretical model of the magnet wheel is derived using air-gap field analysis of linear induction motor, compared with test result and the sensitivity analysis for its parameter change is performed using common tool; MAXWELL. Using two-axial wheel set-up, the tracking motion is tested for a copper plate with its normal motion constrained and its result is given. In conclusion, it is estimated that the magnet wheel using partial shield can be applied to a noncontact conveyance of the conducting plate.