• Journal of Magnetics
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• v.15 no.2
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• pp.74-77
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• 2010

This paper deals with optimum design criteria for maximum torque density & minimum torque ripple of a Flux Switching Motor (FSM) using response surface methodology (RSM) & finite element method (FEM). The focus of this paper is to find a design solution through the comparison of torque density and torque ripple which vary with rotor shape. And then, a central composite design (CCD) mixed resolution was introduced and analysis of variance (ANOVA) was conducted to determine the significance of the fitted regression model. The proposed procedure allows one to define the rotor dimensions, starting from an existing motor or a preliminary design.

• Proceedings of the KIEE Conference
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• 2011.07a
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• pp.1059-1060
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• 2011

This paper deals with optimum design criteria for maximum torque density & minimum torque ripple of Flux Switching Motor (FSM) using RSM & FEM. The focus of this paper is to find a design solution through the comparison of torque density and torque ripple according to rotor shape variations. And then, a central composite design(CCD) mixed resolution is introduced, and analysis of variance (ANOVA) is conducted to determine the significance of the fitted regression model.

• Journal of the Korean Society of Safety
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• v.25 no.4
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• pp.1-6
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• 2010

Wind power system is composed by 3 major parts, rotor blade, nacelle and tower. Especially, the nacelle cover has an important role to prevent the component of nacelle and rotor from an extreme external circumstance. Therefore it is necessary to analyze and evaluate the stress distribution and deformation for them in the design level. There are two major points in nacelle cover analysis. The one is nacelle cover itself and the other is cover support structure. According to GL specification, this study shows the result that CFRP nacelle cover of wind turbine satisfies the strength and deformation through numerical analysis using the commercial finite element analysis program.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.58 no.9
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• pp.1750-1756
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• 2009

In this paper, 5 kWh class Superconductor Flywheel Energy Storage System (SFES) was constructed including motor/generator, superconductor magnetic bearing(SMB), composite rotor and electromagnetic damper(EMD) system. High speed rotation test was performed after levitating flywheel rotor only using EMD without SMB. the PD controller of EMD was designed. the control system is constructed using xPC which is real time digital control system. the results of high speed rotation test showed that proposed EMD system have sufficient damping in cylindrical mode and conical mode, and vibration of wheel was suppressed below 10 ${\mu}m$.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.38 no.1
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• pp.22-28
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• 2010

To detect the damage in composite structure, nondestructive evaluation techniques are widely used. Tapping test is perhaps the most common technique used for the detection of damage in composite laminates. The method is accomplished by tapping the inspection area with light hammer-like device. The tapping test has the ability that indicates damages in a structure due to a localized change of stiffness. The change in vibration signature may be detected by measurement of the dynamic contact force during impact. In this study, it has been shown that the characteristics of impact force histories from a structure during tapping are changed by the presence of damage such as surface crack and delamination. And impact response analysis has been performed on composite rotor blade with crack to investigate the effect of damage.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2011.04a
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• pp.492-497
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• 2011

Helicopter uses a rotor system to generate lift, thrust and forces, and its aerodynamic environment is generally complex. Unsteady aerodynamic environment arises such as blade vortex interaction. This unsteady aerodynamic environment induces vibratory aerodynamic loads and high aeroacoustic noise. Those are at N times the rotor blade revolutions (N/rev). But conventional rotor control system composed of pitch links and swash plate is not capable of adjusting such vibratory loads because its control is restricted to 1/rev. Many active control methodologies have been examined to alleviate the problem. The blade using active control device manipulates the blade pitch angle at arbitrary frequencies. In this paper, Active Trailing-edge Flap blade, which is one of the active control methods, is designed to modify the unsteady aerodynamic loads. Active Trailing-edge Flap blade uses a trailing edge flap manipulated by an actuator to change camber of the airfoil. Piezoelectric actuators are installed inside the blade to manipulate the trailing edge flap.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.15 no.5
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• pp.1018-1024
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• 2011

For the driving of the sinusoidal type permanent magnet synchronous motor with a maximum continuous torque, the 1200 delayed three phase sinusoidal current inputs which matched with the absolute rotor position are needed at the stator coil. Therefore, the detection of a absolute rotor position is required inevitably. And the right angle relationship between stator magnetic field and rotor magnetic field has to be preserved at a stator by this commutation action. The detection of a absolute position for the commutation can be made generally by the output signal analysis of the encoder attached at a motor shaft. The purposes of this study are to design signal processing logic circuits which could detect the absolute position of motor with a modern encoder system and generate the three reference wave for making sinusoidal current input at a stator coil.

• Journal of the Korean Society for Nondestructive Testing
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• v.37 no.2
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• pp.91-98
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• 2017

Recently, composite materials have been mainly used in the main wings, ailerons, and fuselages of aircraft and rotor blades of helicopters. Composite materials used in rapid moving structures are subject to impact by hail, lightning, and bird strike. Such an impact can destroy fiber tissues in the composite materials as well as deform the composite materials, resulting in various problems such as weakened rigidity of the composite structure and penetration of water into tiny cracks. In this study, experiments were conducted using a 2 kW halogen lamp which is most frequently used as a light source, a 2 kW near-infrared lamp, which is used for heating to a high temperature, and a 6 kW xenon flash lamp which emits a large amount of energy for a moment. CFRP composite sandwich panels using Nomex honeycomb core were used as the specimens. Experiments were carried out under impact damages of 1, 4 and 8 J. It was found that the detection of defects was fast when the xenon flash lamp was used. The detection of damaged regions was excellent when the halogen lamp was used. Furthermore, the near-infrared lamp is an effective technology for showing the surface of a test object.

• Proceedings of the KIEE Conference
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• 1999.07d
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• pp.1780-1782
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• 1999

The ultrasonic motor used here is the windmill type ultrasonic motor operated by single-phase AC source. A metal-ceramic composite component was used as the stator element to generate ultrasonic vibrations. The windmill type ultrasonic motors has only three components; a stator element of two wind-mill shape slotted metal endcaps, a rotor and a bearing. In this paper we proposed a system for torque measurement of piezoelectric ultrasonic motor.

• Journal of Advanced Marine Engineering and Technology
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• v.32 no.1
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• pp.20-26
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• 2008

The nacelle cover and nosecone are made of composite materials, especially the stiffener is added in the nacelle cover in order to enhance it's stiffness. The nacelle cover consists of all three covers of left, right side cover and upper cover and each cover is connected with bolts. Also, the nacelle cover and nacelle frame are connected with bolts. The nacelle cover and nosecone have a important role to prevent the components of nacelle and rotor from external circumstances such as snow, rain and wind. Therefore, it is necessary to analyze and evaluate the strength and deformation for them in the design level. According to GL Wind Specifications, this paper shows the results that nacelle cover of 2MW wind turbine satisfy the strength and deformation throughout analysis using Patran/Nastran programs.