• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2008.11a
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• pp.563-569
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• 2008

In this study, fluid/structure coupled analyses have been conducted f3r 3-D stator and rotor configuration. Advanced computational analysis system based on computational fluid dynamics (CFD) and computational structural dynamics (CSD) has been developed in order to investigate fluid/structure responses of general stator-rotor configurations. To solve the fluid/structure coupled problems, fluid domains are modeled using the structural grid system with dynamic moving and local deforming techniques. Reynolds-averaged Navier-Stokes equations with Spalart-Allmaras (S-A) and SST ${\kappa}-{\omega}$ turbulence models are solved for unsteady flow problems. A fully implicit time marching scheme based on the Newmark direct integration method is used for computing the coupled aeroelastic governing equations of the 3-D turbine blades for fluid-structure interaction (FSI) problems. Detailed fluid/structure analysis responses for stator-rotor interaction flow conditions are presented to show the physical performance and flow characteristics.

• KIEE International Transaction on Electrical Machinery and Energy Conversion Systems
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• v.11B no.2
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• pp.22-27
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• 2001

Salient pole rotor type single phase switched reluctance motor is of simple and rigid structure, short shaft and simple driving circuit. Especially, the output power per unit volume of salient pole rotor structure is comparatively high because the magnetic fluxes of axial and radial direction are simultaneously used. Therefore, this motor will be used at small space and difficult maintenance situations. In this paper, the selecting method of proper pole arc, stator, and rotor dimension of salient pole rotor type single phase SRM is proposed.

• Bulletin of the Korean Chemical Society
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• v.27 no.4
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• pp.515-518
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• 2006

It is explicitly shown that a supersymmetry structure exists in the spectrum of a rigid symmetric top rotor in the molecule-fixed frame. Using projection operators constructed from the time-reversal symmetry of the rotor, the full rotor Hamiltonian is separated into two parts, i.e., the bosonic and fermionic components. The construction, without ambiguity, suggests that the rotor has a supersymmetry in it. This supersymmetry is mathematically equivalent to that of the free rotor on a plane recently noted by Rau.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.36 no.12
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• pp.1139-1145
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• 2008

numerical study on the coupled fluid-structure for a rotor blade in hover was conducted. Computational fluid dynamics code with enhanced wake-capturing capability is coupled with a simple structural dynamics code based on Euler-Bernoulli's beam equation. The numerical results show a reasonable blade structural deformation and aerodynamic characteristics.

• Proceedings of the KIPE Conference
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• 2014.11a
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• pp.39-40
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• 2014

In this paper, a novel 12/8 segmental rotor type switched reluctance motor (SRM) is proposed. Different from conventional structures, the proposed rotor consists of a series of discrete segments, and the stator is constructed from two types of stator poles: exciting and auxiliary poles. Moreover, in this structure short flux paths are taken and no flux reverse exists in the stator. While the auxiliary poles are not wound by the windings, which only provide the flux return path. Compared with conventional 12/8 SRM, the proposed structure increases the electrical utilization of the machine and decreases the core losses, which may lead to high efficiency. To verify the proposed structure, finite element method (FEM) is employed to get static and dynamic characteristics. Finally, a prototype of the proposed motor is tested for characteristics comparisons.

• The Transactions of the Korean Institute of Power Electronics
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• v.27 no.1
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• pp.80-83
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• 2022

This paper proposes an initial rotor polarity detection algorithm of a single-phase permanent magnet synchronous motor (SP-PMSM) related to stable open-loop starting for sensorless operation. Generally, the SP-PMSM needs an asymmetric air-gap structure to can avoid the initial starting failure at zero torque point. Therefore, the rotor polarity information can be obtained by using the DC offset current direction of a stator current through a high frequency voltage injection into an SP-PMSM with an asymmetric air gap. In this paper, the proposed rotor initial polarity detection algorithm is verified through several experimental results.

• Proceedings of the KIEE Conference
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• 2011.07a
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• pp.1101-1102
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• 2011

In this paper, characteristic of switched reluctance motor for bike is compared according to rotor structure. Comparison results is verified with simulation which give same condition for design and control.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.36 no.7
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• pp.731-738
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• 2012

In this study, the evaluation of the aerodynamic characteristics of the NREL Phase VI Rotor System has been performed, for the 7 m/s upwind case using commercial FEA and CFD tools which are ANSYS Mechanical 12.1 and CFX 12.1. The initial operating conditions of the rotor blade include a $3^{\circ}$ tip pitch angle. A numerical simulation was carried out on only the rotor parts, excluding the tower structure based on the equivalent stiffness model, to consider the aeroelastic effect for the numerical simulation using the loosely coupled 2-way fluid-structure interaction method. The blade root bending moment was monitored in real time to obtain reasonable results. To verify the analysis results, the numerical simulation results were compared with the measurements in the form of the root bending moment and the pressure distributions of the NREL/NASA Ames wind tunnel test.

• Journal of Power Electronics
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• v.14 no.5
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• pp.866-873
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• 2014

In this paper, a novel 12/8 segmental rotor type switched reluctance motor (SRM) is proposed for cooling fan applications. Unlike conventional structures, the rotor of the proposed structure is constructed from a series of discrete segments, and the stator is constructed from two types of stator poles: exciting and auxiliary poles. Moreover, in this structure, short flux paths are taken and no flux reversion exists in the stator. While the auxiliary poles are not wound by the windings, which only provide the flux return path. When compared with the conventional SRM, the proposed structure increases the electrical utilization of the machine and decreases the core losses, which may lead to a higher efficiency. To verify the proposed structure, the finite element method (FEM) and Matlab-Simulink are employed to get the static and dynamic characteristics of the proposed SRM. Finally, a prototype of the proposed motor was tested for characteristic comparisons.

• Advances in aircraft and spacecraft science
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• v.6 no.1
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• pp.31-49
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• 2019

Flutter is a dangerous phenomenon encountered in flexible structures subjected to aerodynamic forces. This includes aircraft, helicopter blades, engine rotors, buildings and bridges. Flutter occurs as a result of interactions between aerodynamic, stiffness and inertia forces on a structure. The conventional method for designing a rotor blade to be free from flutter instability throughout the helicopter's flight regime is to design the blade so that the aerodynamic center (AC), elastic axis (EA) and center of gravity (CG) are coincident and located at the quarter-chord. While this assures freedom from flutter, it adds constraints on rotor blade design which are not usually followed in fixed wing design. Periodic Structures have been in the focus of research for their useful characteristics and ability to attenuate vibration in frequency bands called "stop-bands". A periodic structure consists of cells which differ in material or geometry. As vibration waves travel along the structure and face the cell boundaries, some waves pass and some are reflected back, which may cause destructive interference with the succeeding waves. In this work, we analyze the flutter characteristics of a helicopter blades with a periodic change in their sandwich material using a finite element structural model. Results shows great improvements in the flutter forward speed of the rotating blade obtained by using periodic design and increasing the number of periodic cells.