• Title/Summary/Keyword: Exciting frequency

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Noise Analyses of VVVF Inverter and DC/DC Converter for Maglev Train (자기부상열차용 VVVF 인버터 및 DC/DC 컨버터의 소음해석)

  • 김현실;김재승;강현주;김봉기;김상렬
    • The Journal of the Acoustical Society of Korea
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    • v.22 no.5
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    • pp.337-344
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    • 2003
  • In DC/DC converter and VVVF inverter, which are the must dominant noise sources of Maglev train, noise is radiated from core and coil excited by MS(Magnetostriction). The main noise source of DC/DC converter is transformer whose spectrum shows strong peaks associated with harmonics of exciting frequency, On the other hand, LIM/VVVF noise is dominated by the harmonics of switching frequency, whereas harmonics of exciting frequency are not significant. As switching frequency is increased in VVVF inverter, it is shown that the harmonics are shifted to higher frequency range. If switching frequency is increased from 700㎐ to 2 ㎑, It is measured that noise can be reduced by 5 to 6 ㏈. Since complete mathematical description of MS phenomena is far beyond the present technology, vibration spectrum is investigated qualitatively in this paper, where effect of increasing switching frequency is confirmed.

Examination of Frequency Dependence of Iron Loss in Magnetic Field Analysis

  • Masato Enokizono;Yuji Fujita
    • KIEE International Transaction on Electrical Machinery and Energy Conversion Systems
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    • v.11B no.3
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    • pp.59-63
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    • 2001
  • This paper presents a new modeling of the two dimensional magnetic property in soft magnetic materials for the magnetic field computations. In this modeling an approximate treatment is introduced to expand the applicable exciting frequency range. The result shows that the new modeling presented here is very useful in simplicity of magnetic field analysis.

An Analysis of Dynamic Characteristics of Tilting Pad Thrust Bearings (틸팅 패드 추력베어링의 동특성 해석)

  • 김종수
    • Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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    • 1997.04a
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    • pp.91-100
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    • 1997
  • In this paper the linearzed stiffness and damping coefficients of tilting pad thrust bearing are calculated by the perturbation method. The coefficients are obtained for a wide range of pivot positions. The effects of exciting frequency and pad mass on stiffness and damping coefficients are investigated. Critical frequencies due to the tilting motions of the pad are presented and are shown to be strongly influenced by the pivot position and pad mass.

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An Analysis of Dynamic Characteristics of Tilling Pad Thrust Bearings (틸팅 패드 추력베어링의 동특성 해석)

  • 김종수
    • Tribology and Lubricants
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    • v.13 no.3
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    • pp.33-41
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    • 1997
  • In this paper the linearized stiffness and damping coefficients of tilting pad thrust bearing are calculated by the perturbation method. The coefficients are obtained for a wide range of pivot positions. The effects of exciting frequency and pad mass on stiffness and damping coefficients are investigated. Critical frequencies due to the tilting motions of the pad are presented and are shown to be strongly influenced by the pivot position and the pad mass.

Effects of Flow Excitation on the Nitrogen Oxide Emission of a Non-Premixed Flame (유동장 자극이 화염의 질소산화물 배출에 미치는 영향)

  • 이기만
    • Fire Science and Engineering
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    • v.18 no.2
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    • pp.34-40
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    • 2004
  • The effects of external flow excitation with various frequencies and amplitudes on the flame behavior and pollution emission characteristics from a laminar jet flame are experimentally investigated. Measurements of $NO_x$ emission indices ($EINO_x$), performed in vertical lifted flame like turbulent with various exciting amplitude at a constant resonance frequency, have been conducted. It was also conducted to investigate the effects of excited frequency at a constant exciting amplitude on $NO_x$ emissions with a various frequency ranged 0 Hz to 2 KHz. From the vertical lifted turbulent flame of the excited jet with resonance frequency by strong excitation was shown that the dependence of $NO_x$ emission could be categorized into three groups Group I of long flame length with high disturbances yielding high $NO_x$ emission, Group II of intermediate flame length and relative narrow flame volume with low disturbance yielding low $NO_x$ emission and Group III of long flame length and large flame volume with high time & space disturbances behaviour yielding high $NO_x$ emission.

Autonomic and Frontal Electrocortical Responses That Differentiate Emotions elicited by the Affective Visual Stimulation

  • Sohn, Jin-Hun;Lee, Kyung-Hwa;Park, Mi-Kyung;Eunhey Jang;Estate Sokhadze
    • Proceedings of the Korean Society for Emotion and Sensibility Conference
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    • 2000.04a
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    • pp.15-25
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    • 2000
  • Cardiac, respiratory, electrodermal and frontal (F3, F4) EEG responses were analyzed and compared during to slides of International Affective Picture System (IAPS) in the study on 42 students. Physiological responses during 20s of exposure to slides intended to elicit happiness (nurturant and erotic), sadness, disgust, surprise, fear or anger emotions were quite similar and were expressed in heart rate (HR) deceleration, decreased HR variability (HRV), specific SCR, increased non-specific SCR frequency (N-SCR), and EEG changes exhibited in theta increase, alpha-blocking and increased beta activity, and frontal asymmetry. However, some emotions demonstrated variations of the response magnitudes, enabling to differentiate some paris of emotions by several physiological parameters. The profiles showed higher magnitudes of HRV and EEG responses in exciting (i.e., erotic) and higher cardiac and respiratory responses in surprise. The most different pairs were exciting-surprise (by HR, HRV, theta, and alpha asymmetry), exciting-sadness (by theta, alpha, and alpha asymmetry), and exciting-fear (by HRV, theta, F3 alpha, and alpha asymmetry). Nurturant happiness yielded the least differentiation. Differences were found as well within negative emotions, e.g., anger-sadness were differentiated by HRV and theta asymmetry, while disgust-fear by N-SCR and beta asymmetry. Obtained results suggest that magnitudes of profiles of physiological variables differentiate emotions evoked by affective pictures, despite that the patterns of most responses were featured by qualitative similarity in given passive viewing context.

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Investigations on Improvement of Vehicle Design Feature on Idle Shake with Automatic Transmission (자동변속기 장착 차량의 아이들 셰이크 진동 성능 개선 대책에 대한 고찰)

  • Choi, Cheon;Suh, Myung-Won;Kim, Young-Gin
    • Transactions of the Korean Society of Automotive Engineers
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    • v.8 no.4
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    • pp.110-120
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    • 2000
  • In order to improve the vibration characteristics of mid sized passenger car automatic transmission at idle experimental and theoretical studies have been carried out. Idle shake in "D" range occurs by various reasons such as characteristics of body bending resonance between subsystems and engine mounts etc. Using full vehicle finite element analyses and modal tests we introduce the way to reduce the idle shake in the early design stage. It shows that the exciting forces are the 2nd order torque and force of engine. A powertrain system modes in "D" range are entirely effected by the additional boundary conditions of drive line. As a result the frequencies of subsystems are arranged to be lined up at the idle frequency range in order to avoid the resonances with subsystems To reduce the idle shake mounts of radiator are tuned to act as a dynamic damper to 1st bending frequency of the body. In addition a hydraulic mount which is optimized by Phase Shift Method is applied to the rear engine mount.e rear engine mount.

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Velocity Change of Magneto Surface Acoustic Wave (MSAW) in $({Fe_{1-x}}{Co_x})_{89}{Zr_{11}}$ Amorphous Films (I) ($({Fe_{1-x}}{Co_x})_{89}{Zr_{11}}$비정질 자성 막에서의 자기표면탄성파 속도변화 (I))

  • Kim, Sang-Won
    • Korean Journal of Materials Research
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    • v.11 no.6
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    • pp.477-482
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    • 2001
  • The velocity changes of magneto surface acoustic wave (MSAW) have been investigated in the MSAW devices composed of wedge type transducer and as-sputtered ($Fe_{1-x}$ $Co_{x}$ )$_{89}$ $Zr_{ 11}$ (x=0~1.0)amorphous films on glass substrates. The velocity changes of devices depended sensistively on exciting frequency of MSAW, applying the DC bias magnetic field. film thickness and film composition. Particularly. it was conformed that velocity changes increased with the increase of the exciting frequency of MSAW and the thickness of magnetic films. A device deposited x= 0.8 film along the MSAW propagation direction among the devices exhibited a large velocity change of 0.062% at 8.7 MHz for the applied field of 70 Oe.

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A Design Technology of Ceramic Tube for High Efficiency Ozone

  • Cho, Kook-Hee;Kim, Young-Bae;Lee, Dong-Hoon
    • KIEE International Transactions on Electrophysics and Applications
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    • v.3C no.3
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    • pp.77-80
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    • 2003
  • An innovative ozonizer has been developed using a high frequency, surface discharge and a high purity Ti-Si-AI ceramic catalyst as a dielectric component. Using a type of thin film, a thin cylindrical compound ceramic catalyst layer was adhered to the outside surface of its inner electrode. An alternating current (AC) exciting voltage with frequencies from 0.6 KHz to 1.0 KHz and peak-to-peak voltages of 4-6 ㎸ was applied between the electrodes to produce a stable high-frequency silent discharge. A substantial reduction of the exciting voltage was also enabled by means of a thin Ti-Si-Al ceramic catalyst tube. As a result, the ozonizer can effortlessly obtain the required ozone concentration (50-60 g/$m^2$ for oxygen) and high ozone efficiency consumption power (180 g/kWh for oxygen) with-out the assistance of any particular methods. For purposes of this experiment, oxygen gas temperature was set at 2$0^{\circ}C$, with an inner reactor pressure of 1.6 atm at 600 Hz and a flow rate of 2 l/min.

Noise reduction of a high precision gearbox based on experimental study (실험적 방법을 통한 고정밀 감속기의 소음 저감)

  • Lee, Kyu-Ho;Kim, Woo-Hyung;Chung, Jin-Tai
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2006.05a
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    • pp.266-270
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    • 2006
  • Noise reduction the noise of a high precision multi-stage gearbox applied at the industrial robot is investigated by experiment such as the modal test and the signal analysis. The signal analysis performed with the waterfall plot representing the power spectrum as a function of the rotating speed. An eccentric load is installed at the gearbox in order to organize similar condition used in the industrial robot. Exciting sources are found out by the waterfall plot, and then the main factor to make the noise is distinguish. For the low-noise gearbox, the gear design parameter is modified and this gearbox is experimented in the same procedure. The results of the test show the noise level of gearbox reduced.

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