• 대한전기학회:학술대회논문집
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• 대한전기학회 2006년도 제37회 하계학술대회 논문집 D
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• pp.2155-2156
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• 2006

The purpose of this work is to investigate the fundamental properties of the gradual muscle force potentiation for the prediction of muscle force and body movement from the stimulation input with musculo-skeletal model. We investigated the dependence of force potentiation on both the pulse-amplitude and the pulse-duration. The experimental result showed that the force increment ratio during electrical stimulation decreased with pulse-amplitude. The force increment ratio decreased with short pulse-duration and was maintained to be constant with pulse-duration longer than $500{\mu}s$. A new model of the muscle potentiation based on these results is desired in the future.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2007년도 춘계학술대회 논문집 전기기기 및 에너지변환시스템부문
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• pp.134-137
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• 2007

By enforcing skew of permanent magnet, detent force decreases, but lateral force that acts for vertical direction of moving direction occurs. This force deteriorates various performance of PMLSM as that acts to friction force between mover and LM guide. Therefore, in this paper, V skew model is proposed for lateral force's reduction and simulation results are compared to experimental value.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2003년도 하계학술대회 논문집 B
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• pp.942-944
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• 2003

Detent force produced in permanent linear machines generally causes an undesired effect that contributes to the output ripple of machine, vibration and noise. This paper analyzes detent force and thrust in Permanent Magnet Linear Synchronous Motor(PMLSM) by using various detent force minimization techniques. A two dimensional Finite Element Analysis(FEA) is used to Predict detent force and thrust due to structural factors and non-linearity.

• 대한전기학회논문지:전기기기및에너지변환시스템부문B
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• 제55권4호
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• pp.209-215
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• 2006

Recently Permanent Magnet Linear Synchronous Motors(PMLSMs) are widely used for many linear transportation applications. The PMLSM has many advantages such as simple structure, high speed and thrust. However, especially in short primary type PMLSM, there exists very large detent force, which makes the thrust force ripple, undesired vibration and noise. The detent force is composed of the Cogging force and the End force. The Cogging force comes from the interaction between the permanent magnets and interior teeth of the stator. And the End force acts on the exterior teeth of the stator by the permanent magnets. Usually End force is larger than Cogging force, so the detent force is drasically reduced only by reducing the End force. This paper shows the End force is minimized by optimizing the stator length and chamfering the shape of the exterior teeth of the stator.

• Journal of Electrical Engineering and Technology
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• 제12권4호
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• pp.1683-1689
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• 2017

Wheelsets are an important component affecting the dynamic characteristics of railway vehicles. Research on wheelsets has been conducted for a long time. It is possible to generate the restoring force by the individual torque control of the left and right wheels in the independently rotating wheelsets (IRWs). Although this method solves the problems of conventional wheelsets, such as the solid axle wheelsets, the restoring force control must be added to the existing traction force control, and the restoring force requires a higher precision and quicker response than the traction force. In this paper, we study the robust control strategy of wireless trams with independently rotating wheelsets. The interior permanent magnet synchronous motor (IPMSM) and the controller with the actual scale wireless tram are designed to verify the torque control performance. Moreover, we propose an open loop control method to test and verify the traction and restoring force control algorithm of the IRWs.

• KIEE International Transactions on Electrophysics and Applications
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• 제5C권6호
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• pp.264-269
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• 2005

The electrostatic comb drive actuator is one of the main building blocks in the field of micro electro-mechanical systems (MEMS). Most of the comb actuators presented previously have fingers that are rectangular in shape which produce a stable, constant force output during actuation. The use of sawtooth fixed fingers in a comb drive, which were presumed to produce an increasing force output with displacement due to the increased number of regions where fringing force, the driving force of comb actuators, appear. The dimensions of the sawtooth were derived from finite element analysis (FEA) of simplified finger models with sawtooth type fingers of various dimension and were compared to the rectangular finger model that showed that the sawtooth type fingers have $7\~9$ times stronger driving force. Finally, comb drive actuators with sawtooth type and rectangular fingers were fabricated and although the gap was bigger, the comb actuator with sawtooth type fingers showed about 1.7 times greater electrostatic force than the one with rectangular fingers at equal driving voltages. In conclusion, using the proposed sawtooth type comb fingers in a comb drive makes it possible to increase its displacement or reduce the driving voltage.

• 대한전기학회논문지:전력기술부문A
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• 제48권8호
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• pp.1046-1053
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• 1999

The musculotendon model is presented to show the declines in muscle force and shortening velocity during muscle fatigue due to the repeated functional electrical stimulation (FES). It consists of the nonlinear activation and contraction dynamics including physiological concepts of muscle fatigue. The activation dynamics represents $Ca^{2+}$ binding and unbinding mechanism with troponins of cross-bridges in sarcoplasm. It has the constant binding rate or activation time constant and two step nonlinear unbinding rate or inactivation time constant. The contraction dynamics is the modified Hill type model to represent muscle force - length and muscle force - velocity relations. A muscle fatigue profile as a function of the intracellular acidification, pH is applied into the contraction dynamics to represent the force decline. The computer simulation shows that muscle force and shortening velocity decline in stimulation time. And we validate the model. The model can predicts the proper muscle force without changing its parameters even when existing the estimation errors of the optimal fiber length. The change in the estimate of the optimal fiber length has an effect only on muscle time constant in transient period not on the tetanic force in the steady-state and relaxation periods.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1995년도 하계학술대회 논문집 A
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• pp.68-70
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• 1995

The controller for magnetically suspended vehicles considering the speed characteristics is presented. Generally, the attraction force of magnet is determined by input current and air gap. However, when MAGLEV runs at high speed, induced eddy currents in the rail decrease the attraction force. Thus control characteristics of MAGLEV become deteriorated. Therefore, the variation of attraction force according to speed must be considered. Thus we analyzed the speed characteristics of the magnet by FEM. Also, we study on the control characteristics according to speeds, and design the controller considering the decline of levitation force using Neural Network.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2003년도 ICCAS
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• pp.1598-1602
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• 2003

The parallel-type mechanism provides more accurate and stiff motion than the serial-type mechanism. However, in case of using the haptic device, the performance of the force reflection can be deteriorated due to the singular points existing in workspace. In this paper, we propose a redundantly actuated parallel 3-DOF haptic device, which is singularity-free in the workspace and has an improved force reflection capability. In addition, we propose a new force distribution algorithm, which can reflect force of both high and low resolution, using two sets of actuator with different size. Redundant actuators are attached to the base frame in order to minimize the inertia of the system. Moreover, a wire and gear reduction system is employed to achieve high force reflection along with soft feeling. We confirm the performance of the force reflection capability throughout simulation.

• 전기학회논문지
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• 제62권1호
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• pp.43-48
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• 2013

In this paper, magnetic buoyancy force on nonmagnetic solid object submerged in magnetic liquid was simulated and measured. For the evaluation of the force, a multi-physics approach of hydrostatic equilibrium considering magnetic body force as well as gravity is presented. The magnetic body force should be regarded as an additional forcing term in the momentum equation of hydrodynamics. It is also shown that the virtual air-gap based Kelvin's force formula is a useful method for the calculation of force distribution in the magnetic liquid. The experimental result which was performed by a load-cell measurement system agreed quantitatively well with the numerical one.