• International Journal of Precision Engineering and Manufacturing
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• 제9권1호
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• pp.19-24
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• 2008

We propose a new miniature air-bearing stage with a moving-magnet slotless linear motor. This stage was developed to achieve the precise positioning required for submicron-level machining and miniaturization by introducing air bearings and a linear motor sufficient for mesoscale precision machine tools. The linear motor contained two permanent magnets and was designed to generate a preload force for the vertical air bearings and a thrust force for the stage movement. The characteristics of the air bearings, which used porous pads, were analyzed with numerical methods, and a magnetic circuit model was derived for the linear motor to calculate the required preload and thrust forces. A prototype of a single-axis miniature stage with dimensions of $120\;(W)\;{\times}\;120\;(L)\;{\times}\;50\;(H)\;mm$ was designed and fabricated, and its performance was examined, including its vertical stiffness, load capacity, thrust force, and positioning resolution.

• 한국추진공학회:학술대회논문집
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• 한국추진공학회 2003년도 제21회 추계학술대회 논문집
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• pp.20-24
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• 2003

The feasibility of hybrid motor as a first stage of the air launch vehicle is investigated, and the result shows the hybrid motor can replace the solid motor. Optimal design study has been performed for the hybrid motor as a first stage of nanosat air launch vehicle. The first stage hybrid motor of the nanosat air launch vehicle, which uses the F-4E Phantom as a mother plane is designed for given mission requirements. Selected design variables are the number of ports, the initial oxidizer flux, the combustion chamber pressure, and the nozzle expansion ratio. The design results show that a hybrid motor can be successfully applicable to very small air launch vehicles which have severe physical constraints of length and diameter imposed by the mother plane.

• 소음진동
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• 제10권3호
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• pp.401-409
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• 2000

Vibration of a BLDC motor is a coupled phenomenon between mechanical characteristics and magnetic origins through the motor air-gap. When a relative misalignment of rotor in the air-gap center exists on the assemblage it is considered to influence the motor system characteristics, depending on the degree of misalignment. The rotor-motor system used in a washing machine is modeled using FE-TM and a magnetic force of BLDC motor with radial rotor eccentricity is analyzed. And the transient whirl responses of a rotor system with relative misalignment in the motor air-gap are investigated considering mechanical origins and magnetic effects. Results show that rotor misalignment in the air-gap affect the vibration of the rotor-motor system.

• 대한기계학회논문집A
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• 제33권10호
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• pp.1038-1044
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• 2009

In this study, vibrations of an electric motor are analyzed when the motor has the interaction between mechanical and electromagnetic behaviors. For this vibration analysis a 3-phase 8-pole brushless DC motor is selected. Vibrations of the motor are influenced by coupled electromechanical characteristics. The variation of air-gap induced by vibration has an influence on the inductance of the motor coil. To analyze dynamic characteristics of the rotor, we studied inductance by the variation of an air-gap. After obtaining the kinetic, potential and magnetic energies for the motor, the equations of motion are derived by using Lagrange's equation. By applying the Newmark time integration method to the equations, the dynamic responses for the displacements and currents are computed.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2011년도 정기총회 및 추계학술대회 논문집
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• pp.3032-3036
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• 2011

Cooling type of traction motor for EMU in domestic is mostly an open type. Its system is a cooling air entered through air inlet cool down a traction motor and an hot air by traction motor get out air outlet. It is easy to cool it down but hard to maintain it. To improve an ability of maintenance, a total enclosed type traction motor is already developed and used in abroad, not an opne type. So we developed a total enclosed type traction motor which will be used in domestic and abroad EMU. We tried to reduce a weight and a size compared with the abroad one. In contrast with open type traction motors which cool off inside of motors, total enclosed motors cool down by cooling exterior frame of motors. In this case, cooling fins or air fan blowing to the exterior of motors are applied. The total enclosed type traction motor developed by us have two housing to block the foreign substance into inner of a motor and have two cooling fan to easy to reduce a heat happened at a coil. In this paper, design of a cooling structure of the total enclosed traction motor developed twice and performance verification through test will be discussed.

• 전기학회논문지
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• 제58권9호
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• pp.1735-1740
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• 2009

This study presents a brushless DC (BLDC) motor for air management system of fuel cell modules. Magnetic equivalent circuit model and finite element analysis are used to design the motor, and an improved structure is considered to reduce a mechanical loss induced from bearing units. Finally, air blower system combined with the motor and an impeller is manufactured and output properties, such as an air pressure and an amount of flowing air, are measured. Through the experimental results, a validity of the simulated one is confirmed.

• Journal of Electrical Engineering and Technology
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• 제4권2호
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• pp.255-265
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• 2009

This paper presents the acoustic noise and mechanical vibration reduction of a coreless brushless DC motor with an air dynamic bearing used in a digital lightening processor. The coreless brushless DC motor does not have a stator yoke or stator slot to remove the unbalanced force caused by the interaction between the stator yoke and the rotor magnet. An unbalanced force makes slotless brushless DC motors vibrate and mechanically noisy, and the attractive force between the magnet and the stator yoke increases power consumption. Also, when a coreless brushless DC motor is driven by a $120^{\circ}$ conduction type inverter, high frequency acoustic noise occurs because of the peak components of the phase currents caused by small phase inductance and large phase resistance. In this paper, a core-less brushless DC motor with an air dynamic bearing to remove mechanical vibration and to reduce power consumption is applied to a digital lightening processor. A $180^{\circ}$ conduction type inverter drives it to reduce high frequency acoustic noise. The applied methods are simulated and tested using a manufactured prototype motor with an air dynamic bearing. The experimental results show that a coreless brushless DC motor has characteristics of low power consumption, low mechanical vibration, and low high frequency acoustic noise.

• 전기학회논문지
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• 제56권9호
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• pp.1571-1576
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• 2007

This report describes the analytical characteristic of sinewave air gap flux density for the brushless AC motor with surface permanent magnet. The analysis of sinewave air gap flux density is the key to expect the performance of back EMF for the design of brushless AC motor. The numerical analysis and FEM analysis are performed to adopt radial and parallel flux magnetization of magnet on the rotor. And it is also executed to vary the magnet arc angle and arc radius for the condition of constant and non constant air gap. This report is focused on the characteristic of sinewave air gap flux density for permanent magnet of surface brushless AC motor. This results also have more reliable data against the previous paper which had the representative numerical analysis of air gap flux density[1][2].

• 대한전기학회논문지:전기기기및에너지변환시스템부문B
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• 제51권2호
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• pp.49-54
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• 2002

Most single-Phase brushless DC (BLDC) motors have unequal air gap to eliminate the dead-point where the developed torque value is zero. However this partial increase of the air gap deteriorates the motor characteristics in cogging torque. Thus in this paper a new topology of unequal air gap is proposed to solve this problem. The topology is to use some pairs of equal or unequal air gaps. As a result, it is proved by the finite element analysis and experimental results that the single-Phase BLDC motor with the proposed air gap topology is very effective in reducing the cogging torque.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2002년도 추계학술대회논문초록집
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• pp.380.2-380
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• 2002

SRM(Switched Reluctance Motor) 내부의 Radial Force는 소음ㆍ진동의 주원인이 되는 가진력으로 작용하는 것으로 알려져 있다. 따라서 본 논문에서는 Radial Force의 주 요인인 Motor 내부의 Air Gap 편심에 따른 반경방향의 전자기 가진력을 전자장 수치해석을 통하여 해석하고 소음ㆍ진동에 미치는 영향을 분석하였다. Air Gap 편심량을 변화시켜 가면서 Stator, Rotor의 Local Force와 Gloval Force인 Torque Fluctuation을 해석하고 이를 실험 결과와 비교함으로서 해석결과의 타당성을 입증하였다.