• 전기의세계
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• v.25 no.2
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• pp.40-45
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• 1976

유도전동기의 고주파진동토오크의 산정법에 대하여는 Morrill, Chang, Puchstein Kimball 및 Veinott씨 등에 의한 불평형공간자속분포의 대칭좌표법 또는 2회전자계법해석으로 많은 연구가 거듭되어 기계정수가 고주파토오크에 미치는 영향의 관계를 풀이하고 있다. 또한 Jordan과 Lax씨에 의하여 편심 및 기계적진동에 따른 전자력파의 분포력 mode수 및 그 주파수를 개발함으로서 소음방지대책에 많은 진전을 보았다. 소음진동측정방법으로는 원래 진동측정이 정밀한 장치에 의존하여야 하며 그 방법 또한 어려운 점이 많아 method of 1-point measurement of electromagnetic-force waves로 처리되어 왔으나 요즈음에는 anechoic chamber와 같은 장치에서의 특별한 조작에 의하여 method of resultant measurement of accoustic noise powers에 의하여 보다 합리적인 소음측정 및 해석이 가능하게 되었다.

• Transactions of the Korean Society of Mechanical Engineers
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• v.18 no.5
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• pp.1253-1263
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• 1994

The experimental study is carried out to identify the combustion generated noise mechanism in free turbulent jet diffusion flames. Axial mean fluctuating velocities in cold and reacting flow fields were measured using hot-wire anemometer and LDv.The overall sound pressure level and their spectral distribution in far field with and without combustion were also measured in an anechoic chamber. The axial mean velocity is 10-25% faster and turbulent intensities are about 10 to 15% smaller near active reacting zone than those in nonreacting flow fields. And sound pressure level is about 10-20% higher in reacting flow fields. It is also shown that the spectra of the combustion noise has lower frequency characteristics over a broadband spectrum. These results indicate that the combustion noise characteristics in jet diffusion flames are dominated by energy containing large scale eddies and the combusting flow field itself. Scaling laws correlating the gas velocity and heat of combustion show that the acoustic power of the combustion noise is linearly proportional to the 3.8th power of the mean axial velocity rather than 8th power in nonreacting flow fields, and the SPL increases linearly with logarithmic 1/2th power of the heat of combustion.

• 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.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 1991.04a
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• pp.83-89
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• 1991

본 연구에서는 5축 능동형 자기베어링 시스템에 대한 설계 및 제작 방법을 소개하고 모우드 변수 및 임계속도, 과도 및 정상상태에서의 응답 특성 등 관련 동특성을 실험으로 규명하였다. 자기베어링 제어방식은 PID 제어를 이 용하였고, air jet를 이용하여 회전체를 구동할 수 있도록 실험장치를 구성하 였다. 실험을 통하여 안정한 부상특성을 실현하였고, 1,2차의 임계속도를 통 과하여 10,000rpm이상이 회전속도에서도 안정하게 운전할 수 있었다.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.26 no.7
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• pp.875-880
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• 2016

A new hybrid permanent magnet biased magnetic levitation actuator (maglev) is developed. This new maglev actuator is composed of two C-core electromagnetic cores separated with two permanent magnets. Compared to the conventional hybrid maglev actuators, the new actuator has unique flux paths such that bias flux paths are separated with control flux paths. The control flux paths have minimum reluctances only developed by air gaps, so the currents to produce control fluxes can be minimized. The gravity load can be compensated with the permanent magnet bias fluxes developed at off-centered air gap positions while external disturbances are controlled with control fluxes by currents. The consumed power to operate this levitation system can be minimized. 1-D magnetic circuit model is developed for this model such that the flux densities and magnetic forces are extensively analyzed. 3-D finite element model is also developed to analyze the performances of the maglev actuator.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2008.04a
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• pp.566-568
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• 2008

An E-OPMT(Electronically-controllable OPMT) was developed as an alternative of OPMT which could adjust the direction of the generated guided waves in a plate manually. The key idea of controlling the wave direction electronically is based on a few sets of axisymmetric figure-of-eight coils and the magnet which is located for making static omni-directionally biasing magnetic field over the patch. However, in order to explain wave phenomenon generated by this transducer, a new approach is required because there are various combinations between static biasing magnetic field and dynamic actuating magnetic field on the patch, not similar to OPMT. In this paper, the experiments were performed to understand characteristics of E-OPMT and the new theoretical analysis was set up for explaining the result.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2008.04a
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• pp.807-808
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• 2008

This is concerned with the radiation pattern of elastic waves in a plate generated by an orientation-adjustable patch-type magnetostrictive transducer. In general, not only the Lamb waves but also shear horizontal (SH) waves are produced by the deformation of the circular magnetostrictive patch bonded to a plate. Among the two types of waves, this paper investigates the radiation patterns of SH waves. A number of experimental results are presented. They are also accurately predicted by a theory developed by the present authors. Experimental findings were explained by a theoretical analysis.

• 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.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.11 no.6
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• pp.223-232
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• 2001

Aiming at a small axial pump with a levitated rotor, an axial-type self-bearing motor is presented, which has a rotor wish four permanent magnets and two stators with two-pole three-phase windings. In this system, only the axial motion of rotor is actively controlled by two opposite self-bearing motors just like in the case of an axial magnetic bearing, while the other motions are passively stable. For rotation, It follows the theory of a four-pole three-phase synchronous motor. This paper Introduces schemes for design and control of the self-bearing motor and shows some experimental results to Prove the feasibility of application for the axial Pump.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2009.10a
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• pp.268-269
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• 2009