• Journal of the Korea Academia-Industrial cooperation Society
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• v.21 no.1
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• pp.277-283
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• 2020

In a concentric magnetic gear, which replaces the teeth of a mechanical gear with a permanent magnet, the polar ratio of the magnet that determines the reduction ratio affects the behavior of the magnetic gear dramatically. This study analyzed the density of transmission torque, the efficiency of torque considering the solid loss, and the torque quality, including the cogging characteristics using finite element analysis. When the pole number on the driving side was changed from two to five, it was confirmed that there was an optimal pole ratio, in which the transmission torque was maximized. Because eddy current generation density is proportional to the magnetic field, the transmission efficiency also shows a similar tendency to the transmission torque density, and the efficiency is more than 95% at a low gear ratio. The cogging characteristics due to the interaction of the permanent magnets with the limited number of poles are inversely proportional to the least common multiple between the number of magnets on the drive side and the number of modulator teeth. A test model was built for the transmission torque evaluation.

• Proceedings of the KSR Conference
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• 2011.05a
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• pp.924-931
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• 2011

This paper deal with maximum span calculation technique for 350km/h high speed catenary system. Considers a geometric interaction, possible maximum span length is between two pole. Wind condition and the train current collector is moving even to being pantograph does not escape while operating. Uses like this justice and possible maximum span length is follow next condition. (i) Operating range of pantograph fan head, (ii) The wind velocity which assumes from system, (iii) Width in pantograph from operation height moving, (iv) Type of processing Catenary system, specially tensile strength of overhead contact wire and messenger wire etc. When accurately calculates the maximum permission span, the dropper between of overhead contact wire and messenger wire and must consider the correlation.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.29 no.12 s.243
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• pp.1561-1566
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• 2005

In this paper, a new compact active magnetic bearing(AMB) is proposed in which radial and axial bearings are integrated in one bearing unit. It consists of four U-shaped cores circumferentially connected by yokes and two-layer coils for radial and axial controls. For the radial control action, it has the same principle as conventional homopolar AMBs, while for the axial control, it uses the Lorentz force generated by the interaction of the bias flux for radial control and the axial control flux. The proposed structure makes it easy to design a compact AMB because it has no disk for axial control. This paper introduces the proposed structure, principle, and design process based on the magnetic flux analysis. By using a control algorithm with feedforward action to compensate the coupled flux effect, the feasibility of the proposed AMB is experimentally verified.

• Journal of Electrical Engineering and Technology
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• v.10 no.4
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• pp.1667-1673
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• 2015

The vibration and noise caused by the dynamic interaction between electromagnetic suspension and the linear synchronous motor stator beneath a flexible guideway remain problems in designing attractive Maglev trains. One possible method to reduce the sources of vibration is to minimize the detent force in the linear synchronous motor that creates variations in both lift force and thrust. This paper proposes lowering detent force by using separated core instead of single united core. The magnet is designed to adapt to the deflected guideway at a speed of 550km/h. This study will analyze the electromagnetic field and control performance, and how they relate to lift forces and dynamic responses.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.33 no.10
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• pp.1038-1044
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• 2009

In this study, vibrations of an electric motor are analyzed when the motor has the interaction between mechanical and electromagnetic behaviors. For this vibration analysis a 3-phase 8-pole brushless DC motor is selected. Vibrations of the motor are influenced by coupled electromechanical characteristics. The variation of air-gap induced by vibration has an influence on the inductance of the motor coil. To analyze dynamic characteristics of the rotor, we studied inductance by the variation of an air-gap. After obtaining the kinetic, potential and magnetic energies for the motor, the equations of motion are derived by using Lagrange's equation. By applying the Newmark time integration method to the equations, the dynamic responses for the displacements and currents are computed.

• 제어로봇시스템학회:학술대회논문집
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• 2003.10a
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• pp.142-145
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• 2003

Many control applications using Neural Network need a priori information about the objective system. But it is impossible to get exact information about the objective system in real world. To solve this problem, several control methods were proposed. Reinforcement learning control using neural network is one of them. Basically reinforcement learning control doesn't need a priori information of objective system. This method uses reinforcement signal from interaction of objective system and environment and observable states of objective system as input data. But many methods take too much time to apply to real-world. So we focus on faster learning to apply reinforcement learning control to real-world. Two data types are used for reinforcement learning. One is reinforcement signal data. It has only two fixed scalar values that are assigned for each success and fail state. The other is observable state data. There are infinitive states in real-world system. So the number of observable state data is also infinitive. This requires too much learning time for applying to real-world. So we try to reduce the number of observable states by classification of states with Self-Organizing Map. We also use neural dynamic programming for controller design. An inverted pendulum on the cart system is simulated. Failure signal is used for reinforcement signal. The failure signal occurs when the pendulum angle or cart position deviate from the defined control range. The control objective is to maintain the balanced pole and centered cart. And four states that is, position and velocity of cart, angle and angular velocity of pole are used for state signal. Learning controller is composed of serial connection of Self-Organizing Map and two Multi-layer Feed-Forward Neural Networks.

• The Transactions of the Korean Institute of Electrical Engineers B
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• v.49 no.3
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• pp.131-137
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• 2000

2 phase 8 pole HB-type(flat-type) Linear Pulse Motor can be used as the high precision position actuator because of its many advantages (simple control circuit, high stiffness characteristics, etc). Also, using the microstep drive, its noise and vibration can be reduced considerably and positional resolution may be increased further. But, $20^{\circ}$tapered tooth shape to reduce the normal force have an much effect on the static thrust force characteristics. And, because of hybrid-type LPM, interaction between the permanent magnet and the excitation current have an effect on the various characteristics of LPM. Hence, in this paper, the effect of tooth shape on static thrust force characteristics was analyzed using the air gap permeance by finite element method. For analyzing the effect of unbalance between the m.m.f of permanent magnet and the m.m.f of excitation current, unbalanced m.m.f coefficient $\sigma$ were introduced with the permenace matrix and switching matrix.

• The Transactions of the Korean Institute of Electrical Engineers B
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• v.49 no.1
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• pp.1-8
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• 2000

Switched reluctance motor(SRM) has simple magnetic structure, and requires simple power electronic driving circuit. It is very useful for wide range adjustable speed drive system. But, SRM drive generates large vibration and acoustic noise because it is commutated individually by step pulse m.m.f of each phase pole. In the vibration and acoustic noise characteristics. The considerable vibration and noise is induced by radial deforming of stator, so the frequency of dominant vibration and noise is coincident with the frequency of natural mode frequency of mechanical structure. This radial vibration force is generated in the phase commutation region. This paper suggests the new electromagnetic structure of SRM with auxiliary commutation winding which is excited by direct current. This phase and commutation winding are coupled magnetically between one phase winding and the other. Therefore, the switch-off phase current is absorbed by the another phase winding. By this interaction of phase and commutation winding in commutation mechanism, vibration and noise is reduced. And this reduction effect is examined by the test of prototype machine. As a result, SRM with DC exciting commutation winding is very useful to reduce vibration and acoustic noise.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.27 no.5
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• pp.353-360
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• 2014

The model ice is created at KRISO (Korea Research Institute for Ships and Ocean Engineering) ice basin where model ship is tested to obtain the necessary data in order to design the ice breaking vessels and ocean structures operating in the northern pole sea area. Through the model ship test, ice breaking, clearing, ice-ship and ice-propeller interaction behavior can be obtained. Since mechanical properties of ice plate are required for the model test, some tests are performed to obtain the properties in this paper. First, ultrasonic devide is used to measure the thickness of the model ice plate and the results show the possibility of using ultrasonic method, yet more sophisticated device or special sensors are required to measure the ice thickness completely. And the defection of ice plate is measured using LVDT to compute the characteristic length of ice plate on the fluid, which is used to get the effective Young's modulus of model ice.

• Journal of Microbiology
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• v.39 no.4
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• pp.286-292
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• 2001

During mitosis. the proper segregation of duplicated chromosomes is corrdinated by a spindle check-point. The bifurcated spindle checkpoint blocks cell cycle progression at metaphase by monitoring unattached kinetochores and inhibits mitotic exit in response to the misorientation of the mitotic spin- dle Ibd1p/Bfa1p is a spindle checkpoint regulator of budding yeast in the Bub2p checkpoint pathway for mitotic exit and its disruption abolishes mitotic arrest when proper organization of the mitotic spin-dls inhibited. Ibd1p/Bfa1p localizes to the spindle pole body, a microtublue-organizing center in yeast, and its overexpression arrests the cell cycle in 80% of cells with an enlarged budy at mitosis and in 20 % of cells with multiple buds. In this study, we found that the C-terminus of Ibd1p/Bfa1p phys-ically interacts with Skp1p, a key component of SCF (Skp1/cullin/F-box) complex for ubiquition-medi-ated proteolysis of cel cycle regulatores as well as an evolutionally conserved kinetochore protein for cell cycle progression. A putative F-box motif was found in the C-terminus of Ibd1p/Bfa1p and its function was investigated by making mutants of conserved residues in the motif. These Ibd1p/Bfa1p mutants of a putative F-box interacted with SKp1p in vitro by two-hybrid assays as wild type Ibd1p/Bfa1p. Also these Ibd1p/Bfa1p utants displayed the overexpression phenotypes of wild type Ibd1p, when over-expressed under inducible promoters . These results suggest that a putative F-box motif of Ibd1p/Bfa1p is not essential for the interaction with SKp1p and its function in mitotic exit and cytokinesis.