• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2005.05a
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• pp.935-940
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• 2005

In this paper, dual rotor disk configuration with a coreless stator is proposed for the Lorentz force type integrated motor bearing system. An experimental compensation for the effects of high order harmonics is performed using the digital controller of the experimental setup. The runout profile and rotor unbalance are also identified by the extended influence coefficient method. The experimental results confirm that this compensation method effectively attenuates the rotor vibration all over the operating range of rotational speed.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.23 no.10
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• pp.1229-1239
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• 1999

A computational study on unsteady compressible flows has been performed by adopting a low Reynolds number $k-{\omega}$ turbulence model in conjunction with dual time stepping scheme. An explicit four-stage Runge-Kutta scheme for the Navier-Stokes equations and an approximate factorization scheme for the $k-{\omega}$ turbulence model equations are used. Computational results obtained for blade surface pressure distributions in the process of rotor-stator interaction in a turbine stage are in good agreement with extant experimental data. The effects of the wake from the stator on the boundary-layer transition over the rotor blade surface are discussed by showing that high intensity turbulence of the stator wake induces an early transition.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.15 no.9 s.102
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• pp.1045-1052
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• 2005

Tn this paper. dual rotor disk configuration with a coreless stator is proposed for the Lorentz force type integrated motor hearing system. An experimental compensation for the effects of high order harmonics is performed using the digital controller of the experimental setup. The runout profile and rotor unbalance are also identified by the extended influence coefficient method. The experimental results confirm that this compensation scheme effectively attenuates the rotor vibration all over the operating range of rotational speed.

• The Journal of Korea Robotics Society
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• v.5 no.4
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• pp.309-317
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• 2010

This paper proposes an efficient measurement system for the velocity and direction of the wind using the dual rotor wind power generator in vessel. Conventional digital measurement system recognizes the direction and the velocity of the wind using the electric compass or synchronous motor and Vane probe method using hall sensors. But each system has its own short-comings: the synchronous motor has a larger measurement error than the magnetic compass and magnetic compass is weak for the external disturbances such as fluctuation of the vessel. To compensate these short-comings, this paper proposes a new compensation algorithm for the fluctuation errors according to the external interference and the unexpected movement of the vessel along the roll and pitch directions. The proposed system is implemented with the dual compasses and a synchronous motor. The proposed independent power generation system can be operated by itself and can raise the efficiency of the wind power generation systems of 30 ~ 400 W installed along the vertical and horizontal axes. The proposed system also realizes the efficient and reliable power production system by the MPPT algorithm for the real-time recognition of the wind direction and velocity. An advanced switching algorithm for the battery charging system has been also proposed. Effectiveness of the proposed algorithm has been verified through the real experiments and the results are demonstrated.

• Tribology and Lubricants
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• v.36 no.2
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• pp.105-115
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• 2020

This paper presents a numerical study on the rotordynamic analysis of a dual-spool turbofan engine in the context of blade defect events. The blades of an axial-type aeroengine are typically well aligned during the compressor and turbine stages. However, they are sometimes exposed to damage, partially or entirely, for several operational reasons, such as cracks due to foreign objects, burns from the combustion gas, and corrosion due to oxygen in the air. Herein, we designed a dual-spool rotor using the commercial 3D modeling software CATIA to simulate blade defects in the turbofan engine. We utilized the rotordynamic parameters to create two finite element Euler-Bernoulli beam models connected by means of an inter-rotor bearing. We then applied the unbalanced forces induced by the mass eccentricities of the blades to the following selected scenarios: 1) fully balanced, 2) crack in the low-pressure compressor (LPC) and high pressure compressor (HPC), 3) burn on the high-pressure turbine (HPT) and low pressure compressor, 4) corrosion of the LPC, and 5) corrosion of the HPC. Additionally, we obtained the transient and steady-state responses of the overall rotor nodes using the Runge-Kutta numerical integration method, and employed model reduction techniques such as component mode synthesis to enhance the computational efficiency of the process. The simulation results indicate that the high-vibration status of the rotor commences beyond 10,000 rpm, which is identified as the first critical speed of the lower speed rotor. Moreover, we monitored the unbalanced stages near the inter-rotor bearing, which prominently influences the overall rotordynamic status, and the corrosion of the HPC to prevent further instability. The high-speed range operation (>13,000 rpm) coupled with HPC/HPT blade defects possibly presents a rotor-case contact problem that can lead to catastrophic failure.

• Proceedings of the KIEE Conference
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• 2004.10a
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• pp.120-122
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• 2004

In this Paper, high efficiency dual air-gap induction motor with permanent magnet rotor is described. The finite element method is used to design the rotor and magnet. And we presented the analysis, construction, experimental results of prototype single phase induction motor with permanent magnet rotor for air-conditioner fan motor.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.62 no.11
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• pp.1541-1543
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• 2013

This paper presents a spherical motor which can control in multi-degree of freedom operation. The spherical motor has been researched by many types of structure. Thhis paper shows a spherical shaped airgap and surfaced permanent magnets. Especially, The motor consists of dual rotor cores. Unlike a cylindrical motor, the spherical motor design can be considered with azimuth direction on spherical coordinates. Therefore the permanent magnet surfaced on the rotor need to be designed optimally in order to generate a sinusoidal magnetic flux density in the airgap. This paper presents results of optimal design for reducing torque ripple of the multi-degree of freedom spherical motor.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.63 no.7
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• pp.903-909
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• 2014

As a direct drive type washing machine requires two operating modes, washing and spinning modes, a design of the motor with high efficiency in each mode is not applicable to a conventional procedure. To achieve the requirements, a multi-pole outer rotor type switched reluctance motors are considered. To select a suitable motor type for the application, a static toque is compared based on the FEM analysis. The selected type is obtained for high and wide toque than other types of the motor. Further, the pole shape and arc are optimized to meet the required torque and torque ripple. To verify the proposed structure, the prototype is designed and manufactured. And the simulation and experimental results verify the validity of the proposed structure.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2001.07a
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• pp.203-206
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• 2001

A 30kw Dual rotor Turbines HAWT/VAWT combined wind turbine system that can drastically enhance the power production capability compared to conventional Single Rotor Turbine HAWT system. The combined system that takes advantage of strong point of both horizontal and vertical Axis wind turbine system developed by a venture firm KOWINTEC of Chonbuk national university. The HAWT/VAWT hybrid system has been successfully field tested and commercial operating since Feb. 12, 2001 in Hae-chang rest park, Bu-an county near the Sae Man-Kum Sea Dike. This paper will briefly describe the field test results performance and a special aerodynamic structure with bevel-planetary gear box of Dual Rotor Wind Turbine system.

• Journal of Institute of Control, Robotics and Systems
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• v.19 no.2
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• pp.158-163
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• 2013

The fusion of the GPS (Global Positioning System) and DR (Dead Reckoning) is widely used for position and latitude estimation of vehicles such as a mobile robot, aerial vehicle and marine vehicle. Among the many types of aerial vehicles, grater focus is given on the quad-rotor and accuracy of the position information is becoming more important. In order to exactly estimate the position information, we propose the fusion method of GPS and Gyroscope sensor using the DEKF (Dual Extended Kalman Filter). The DEKF has an advantage of simultaneously estimating state value and a parameter of dynamical system. It can also be used even if state value is not available. In order to analyze the performance of DEKF, the computer simulation for estimating the position, the velocity and the angle in a circle trajectory of quad-rotor was done. As it can be seen from the simulation results using own proposed DEKF instead of EKF on own fusion method in the navigation of a quad-rotor gave better performance values.