• Smart Structures and Systems
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• v.3 no.3
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• pp.385-403
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• 2007

The effectiveness of the newly developed smart passive control system employing a magnetorheological (MR) damper and an electromagnetic induction (EMI) part for seismic protection of base isolated structures is numerically investigated. An EMI part in the system consists of a permanent magnet and a coil, which changes the kinetic energy of the deformation of an MR damper into the electric energy (i.e. the induced current) according to the Faraday's law of electromagnetic induction. In the smart passive control system, the damping characteristics of an MR damper are varied with the current input generated from an EMI part. Hence, it does not need any control system consisting of sensors, a controller and an external power source. This makes the system much simpler as well as more economic. To verify the efficacy of the smart passive control system, a series of numerical simulations are carried out by considering the benchmark base isolated structure control problems. The numerical simulation results show that the smart passive control system has the comparable control performance to the conventional MR damper-based semiactive control system. Therefore, the smart passive control system could be considered as one of the promising control devices for seismic protection of seismically excited base isolated structures.

• Nuclear Engineering and Technology
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• v.52 no.7
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• pp.1380-1385
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• 2020

An annular linear induction electromagnetic pump (ALIP) which has a developed pressure of 0.76 bar and a flow rate of 100 L/min is designed to analysis end effect which is main problem to use ALIP in thermohydraulic system of the prototype generation-IV sodium-cooled fast reactor (PGSFR). Because there is no moving part which is directly in contact with the liquid, such as the impeller of a mechanical pump, an ALIP is one of the best options for transporting sodium, considering the high temperature and reactivity of liquid sodium. For the analysis of an ALIP, some of the most important characteristics are the electromagnetic properties such as the magnetic field, current density, and the Lorentz force. These electromagnetic properties not only affect the performance of an ALIP, but they additionally influence the end effect. The end effect is caused by distortion to the electromagnetic field at both ends of an ALIP, influencing both the flow stability and developed pressure. The electromagnetic field distribution in an ALIP is analyzed in this study by solving Maxwell's equations and using numerical analysis.

• 전기의세계
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• v.30 no.4
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• pp.219-226
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• 1981

The magnetic field distribution in saturable iron part of electromagnetic energy conversion divices is defined by the nonlinear quasi-Poisson enquation that is described the electromagnetic field characteristics and satisfied the natural boundary condition. The solution of this equation is obtained by minimizing an energy functional by means of trial function that defined in triangular subregion of two-dimensional field region. As a result, the accuracy of the machine design is increased by use of its solution. In this respect, this study is developed the basic theory to analyze the magnetic flux distribution in saturable iron part and air gap of induction motor that its secondary part is short circuit by the variational principle, the minimized theory of energy functional, the application of F.E.M., and treatment of computer. As theoritical data compared with the practics, the validity of the theory in this study is supported by experimental findings.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2009.10a
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• pp.437-440
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• 2009

High-frequency induction is an efficient way to heat mold surface by electromagnetic induction in a non-contact manner. Thanks to its capability of rapid heating and cooling of mold surface, it has been recently applied to the injection molding. The present study applies the high-frequency induction heating for elimination of weldlines in an injection-molded plastic part. To eliminate weldlines, the mold temperature of the corresponding weld locations should be maintained higher than the glass transition temperature of the resin material. Through experiments, the maximum temperature of $143^{\circ}C$ is obtained on the mold surface around the elliptic coil, while the temperature of the mold plate is lower than $60^{\circ}C$. An injection molding experiment is then performed with the aid of induction heating, and the effect of induction heating conditions on the surface appearance of the weldline is investigated.

• Journal of the Earthquake Engineering Society of Korea
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• v.10 no.6 s.52
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• pp.37-46
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• 2006

In this study, the efficacy of the newly developed smart passive control system to improve seismic performance of base isolated building structures is numerically verified. The smart passive control system consists of a magnetorheological (MR) damper and an electromagnetic induction (EMI) part. The damping characteristics of an MR damper can be controlled by the current generated in an EMI part according to the Faraday's law of electromagnetic induction. An EMI part consisting of a permanent magnet and a solenoid coil could substitute a control system including sensors, a controller and an external power supply in a conventional smart control system. The benchmark control problem for a base isolated building presented by the american society of civil engineers is considered for numerical simulation. The control performance of the smart passive control system is compared to that of the conventional smart control system using MR dampers. It is demonstrated from the numerical simulation results that the smart passive control system is useful to improve the seismic performance of base isolated buildings.

• Journal of Electrical Engineering and Technology
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• v.6 no.3
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• pp.369-374
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• 2011

An induction motor operated with high voltage source generally generates high current in starting mode and has a long transient time after being started. This large and sustaining starting current causes the end windings of the stator to have excessive electromagnetic force. This force is the source of vibration and has a negative and serious influence on the insulation of end windings. Therefore, designing the end winding part with an appropriate support system is needed. To design the support ring enclosing the end windings, we analyze the distribution of electromagnetic force on the end windings by applying the Biot-Savart's law and the 3D finite element method (FEM), and comparing two simulation methods. Finally, we verify the safety of the support structure of the end winding part using stress analysis, which is analyzed with the electromagnetic forces from the 3D FEM simulation.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.17 no.4
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• pp.474-479
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• 2016

As the Eco-energy is recently required, electrical energy is fast increased. Several induction heating methods are attractive for Eco-energy and energy saving. In this paper, electrical fan heater was designed and developed with new concept for energy saving by electromagnetic induction heating. Proposed system was composed of three module, blast part, induction heating part and power transformation part. Induction heating method was adapted for heating and the resonant inverter was used for increasing of the power transformation efficiency. Full-bridge resonant inverter was adopted to resonant inverter. This system was composed of induction heating part made with metal(SUS 40 series), and power transformation part made with rectifier module, filter module and resonant inverter. From these results, the proposed new electric heater could be saved the energy from faster increasing the temperature compared to commercial gas and other electric heater. This electrical fan heater is possible to be used in field of home, commercial and agricultural area for eco-energy saving heater.

• Proceedings of the KSME Conference
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• 2007.05b
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• pp.2621-2625
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• 2007

This study aims at analyzing the flow characteristics of the electromagnetic pump using a linear induction motor (LIM) for transferring molten metals. The flow characteristics of the pump are simulated by magnetohydrodynamic(MHD) program. In this system, the LIM is used for transferring molten metal by electromagnetic force. The molten metal is treated as the secondary part of the LIM. Since the LIM produces an electromagnetic force in the duct, the molten metal can flow from the furnace to the reservoir. The flow characteristics of the pump are analyzed using MHD program for magnetic field of 0.1[T] in duct. In order to prove the analysis, we made a prototype electromagnetic pump using LIM.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2006.04a
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• pp.264-271
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• 2006

Stay cables, such as used in cable-stayed bridges, are prone to vibration due to their low inherent damping characteristics. It has been reported that a semiactive control system using MR dampers could potentially achieve both the better performance compared to a passive control system and the adaptability with few of the detractions. However, a control system including a power supply, a controller and sensors is required to improve the control performance of MR dampers. This complicated control system is not effective to most of large civil structures such as long-span bridges and high-rise buildings. This paper proposes a smart damping system which consists of an MR damper and the electromagnetic induction (EMI) part that is considered as an external power source to the MR damper. The control performance of the proposed damping system has been compared with that of the passive-type control systems employing an MR damper and a linear viscous damper.

• Structural Engineering and Mechanics
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• v.37 no.4
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• pp.443-458
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• 2011

An extensive numerical investigation on the magnetorheological (MR) damper-based smart passive control system for mitigating vibration of stay cables under wind loads has been conducted. The smart passive system is incorporated with an electromagnetic induction (EMI) device for reducing complexity of the conventional MR damper based semi-active control system by eliminating an external power supply part and a feedback control part (i.e., sensors and controller). In this study, the control performance of the smart passive system has been evaluated by using a cable structure model extracted from a full-scale long stay cable with high tension. Numerical simulation results of the proposed smart damping system are compared with those of the passive and semi-active control systems employing MR dampers. It is demonstrated from the results that the control performance of the smart passive control system is better than those of the passive control cases and comparable to those of the semi-active control systems in the forced vibration analysis as well as the free vibration analysis, even though there is no external power source in the smart passive system.