• 한국정밀공학회지
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• 제19권4호
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• pp.140-146
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• 2002

High speed rotating machines can be very sensitive to rotating mass unbalance that is a major source of harmful vibration for many types of rotating machinery. So, the balancing procedure is needed for all high-speed rotating system. To save the time and cost of off-line balancing, many researchers have developed the on-line balancing devices and methods. In this paper, an active balancing device, which is an electro-magnetic type, is developed and the active balancing algorithm using influence coefficient method is also proposed. The active balancing experiment for flexible rotors during operation is performed by an active balancing device. As a result, controlled unbalance responses are below the vibration limit at all rotating speed ranges with critical speed.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1989년도 한국자동제어학술회의논문집; Seoul, Korea; 27-28 Oct. 1989
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• pp.1053-1058
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• 1989

This paper presents the preliminary studies on measurements of dynamic torque in the rotating shaft by utilizing the magnetic lattice. The intensity of torque can be detected as the phase differences between two magnetic sinusoidal signals recorded on magnetic tapes wound on the shaft. This research describes, from the data concerning with phase differences including noise, a method of signal processing to estimate the true value of the torque.

• 천문학회지
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• 제34권4호
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• pp.301-303
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• 2001

We suggest a possible scenario of an astrophysical black hole with non-vanishing electric charge and magnetic flux. The equilibrium charge on a rotating black hole in a force-free magnetosphere is calculated to be Q $\~$ BJ with a horizon flux of ${\~}BM^2$, which is not large enough to disturb the background Kerr geometry. Being similar to the electric charge of a magnetar, in sign and order of magnitude, both electric charge and magnetic flux are supposed to be continuous onto a black hole.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2005년도 추계학술대회 논문집 전기기기 및 에너지변환시스템부문
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• pp.107-109
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• 2005

This paper presents the development of the magnetic position sensor for servo motor. The magnetization system is designed for the sinusoidal magnetic flux density distribution from permanent magnet using 2D finite element method and Preisach model. The magnetic position sensor is composed of the permanent magnet and two Hall elements. And the algorithm calculating the rotating position is suggested by the phase difference of outputs of Hall elements.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2008년도 추계학술대회 논문집
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• pp.99-100
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• 2008

• 한국초전도학회:학술대회논문집
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• 한국초전도학회 2008년도 High Temperature Superconductivity Vol.XVIII
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• pp.93-93
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• 2008

• 천문학회보
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• 제23권
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• pp.42-43
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• 1998

• 대한전기학회:학술대회논문집
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• 대한전기학회 1998년도 하계학술대회 논문집 A
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• pp.343-345
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• 1998

By computer simulation, the pattern of magnetic field distribution on the Nb-foil of a rotating flux type superconducting power supply has been calculated. Using the results, the current pumping rate has been calculated and compared with the results obtained by the experiment. The experiment has been executed with small-size flux-rump in the environment of LN2 and LHe in order to compare the pattern of magnetic filed in the superconducting state and in the normal state. Five hall-sensor was located on the center, right side, left-side, upper side, lower side of the Nb-foil in order to obtain more accurate pattern of the magnetic field generated by rotating pole. In the simulation, the effects of the excitation-magnet and the iron core located at the inner-side and circumference of the magnet have been considered. By comparing the data from the experiment and the results from the simulation, the size of normal spot estimated. At the same time, by calculating the linkage flux, the current-pumping-rate has been obtained. Consequently, the results obtained from experiment and simulation coincided as expected.

• 융복합기술연구소 논문집
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• 제13권1호
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• pp.7-12
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• 2023

The built-in motor with an integrated magnetic gear can realize high torque without a separate reduction device. In this paper, the main design parameters of the magnetic gear constituting the magnetic geared motor are derived and the sensitivity analysis results according to these design parameters are discussed. In particular, processing and assembly issues of modulators sandwiched between rotating bodies are discussed, and loss and magnetic force characteristics of various types of modulators are introduced. Since the modulator, which plays a key role in converting the torque of the magnetic gear, is desirable to have a separate form, it is inevitable to add a non-magnetic support to add torsional stiffness according to high-speed rotation, so the effect of this is also analyzed.

• 한국소음진동공학회논문집
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• 제19권5호
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• pp.537-544
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• 2009

In order to increase the critical speed of rotating disks of which functional material could not be changed such as in optical and magnetic data storage disks, a new disk with a rim reinforced by composite material is proposed and its concept is verified by numerical analysis. Stress distributions are found for the rotating disk composed of two annular disks of which materials are isotropic inside and orthotropic outside. Dynamic equation is formulated in order to calculate the natural frequency and critical speed. For the solution of lateral vibration, a rotational symmertry condition is applied along circumferential direction and a finite element interpolation with Hermite polynomial is performed along the radial direction to obtain a proper solution. According to the results, reinforcing a disk at rim makes critical speeds drastically increased, and induces a buckling phenomenon in mode (0,0) which occurs over the lowest critical speed.