• Title/Summary/Keyword: Air gap

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Effect of Air Gap Insertion on Transmission Loss of Sound Barrier in APAMAT Measurement (APAMAT을 이용한 실험에서 공기층 삽입이 차음재의 투과 손실에 미치는 영향)

  • 신재성;강연준;성명호;김현석
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2001.05a
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    • pp.1180-1184
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    • 2001
  • This paper presents the effect of air gap insertion on the results in measuring the transmission loss of sound barrier by using APAMAT. The measured results show that air gap insertion improves transmission loss as by two-room method or intensity method. The measured results are compared with the predicted transmission loss using MATLAB GUI program based on the transfer matrix method. Predicted results were found to be in reasonable agreement with measured results.

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Air-gap Disturbance Attenuation of Magnetic Levitation Systems using Discrete Kalman Filter (이산형 칼만필터를 이용한 자기부상시스템의 공극외란 감쇄)

  • Sung, H.K.;Jung, B.S.;Jang, S.M.
    • Proceedings of the KIEE Conference
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    • 2004.04a
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    • pp.253-255
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    • 2004
  • Conventional magnetic levitation systems could show unsatisfactory performance under air-gap disturbance due to rail irregularities. In this paper, we propose a feedback control system with discrete Kalman filter for air-gap disturbance attenuation. It is shown that excellent system performance can be obtained with the use of discrete Kalman filter, and that results from experiments agree well with those of simulations.

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Determination of the magnetic field in the air-gap of the linear stepper motor by finite element method (유한요소법에 의한 리니어스텝 모우터의 공극에서의 자계 분석)

  • 이승원;이병하
    • 전기의세계
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    • v.29 no.10
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    • pp.660-666
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    • 1980
  • The finite leement method is a effetive analysis technique for obtaining approximate solutions of continuum problems with boundary conditions. This paper deals with the programming for the application of this method and the preciser analysis of the magnetic field in the air gap of the linear stepper motor by the method. The finite element analysis based on the variational principle is adopted and the computer program for reducing input data and a large number of the memory words required by the system matrix is presented. The 2-dimensional analysis of the air gap is made and several cases according to varying the position are considered.

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Parallel Operation Characteristics of Two Linear Induction Motors (선형 유도전동기의 병렬 운전 특성 실험)

  • Park Seung-Chan;Kim Kyung-Min
    • Proceedings of the KSR Conference
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    • 2005.11a
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    • pp.44-48
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    • 2005
  • In general, the parallel-connected linear induction motors(LIM) are fed by one VVVF inverter in the magnetically levitated vehicle(MAGLEV) or linear motor subway drives. The air gap length of the parallel-connected linear induction motors operating at a grade or curved sections can be different each other. The air gap difference of the two motors attached to the same module causes unequal phase currents, asymmetic thrust and attraction force generation. In this paper, parellel-connected linear induction motors are operated by one IGBT inverter under the different air gap condition so that the phase current characteristics are examined experimentally.

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A Case Study of the Koryo Fine Cracker Using the Air Gap. (Air Gap을 이용한 미진동 화약의 현장적용 사례)

  • 안봉도;조영곤;이익주
    • Explosives and Blasting
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    • v.22 no.1
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    • pp.75-80
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    • 2004
  • 최근 도심지의 가속화에 따라 시가지 인근에서의 암반굴착이 활성화되고 있으며, 특히 보안을 요하는 구조물에 근접한 발과 또는 가동중의 설비 가까이 에서 발파굴착을 실시해야하는 등 주변환경을 충분히 고려하여 진동, 소음 및 비산을 효과적으로 제어할 수 있는 발파기술이 요구되고 있다. 이와 같은 배경에서 미진동 발파굴착을 위하여 콘크리트 파쇄기, 팽창성 파쇄제 등이 개발되어 실용화되고 있다. 국내에서는 (주)한화가 콘크리트 파쇄기(Finecker)를 개발하여 공급해 왔으며, (주)고려 노벨 화약에서는 저폭속(2,000 m/s) 화약을 2중의 Air Gap을 이용하여 진동 및 소음 제어하는 미진동 발파용 화약(Kinecker)을 출시하여 공급하고 있다. 이에 Kinecker의 원리와 특징 그리고 현장적용 사례 및 발파패턴을 소개하고자 한다.

Transient Dynamic Analysis of a Dynamci Eccentric Rotor with Unbalanced Magnetic Forces in BLDC Motors (BLDC 전동기의 동적 편심 및 전자기적 불평형력을 고려한 편심 회전자의 과도 동적 해석)

  • 김태종;황상문;박노길
    • Journal of KSNVE
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    • v.10 no.3
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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.

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Dynamic Analysis of a 3-Phase BLDC Motor Considering Variation of an Air-Gap (공극의 시간변화를 고려한 3 상 BLDC 모터의 동특성 해석)

  • Park, Ki-Sun;Im, Hyung-Bin;Chung, Jin-Tai
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.33 no.10
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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.

A Study on Back EMF of BLDC Motor Using Numetical Analysis Method (수치해석 방법을적용한 BLDC 전동기의 역기전력 연구)

  • Kim, Hyun-Cheol
    • Journal of the Korean Society of Safety
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    • v.23 no.4
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    • pp.36-41
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    • 2008
  • This report describes the analytical solution of back EMF for BLDC motor using numerical analysis of air gap flux density. The analysis of air gap flux density is the key to expect the performance of back EMF for the design of brushless motor. The numerical analysis and FEM analysis are performed to vary attachment of stator side or rotor side, radial flux magnetization or parallel flux magnetization, magnet arc angle in the condition of constant air gap. This results have more reliable data comparing with test result of the back EMF for 7 phase BLDC motor.

Development of On-Line Monitoring System for Pumped Storage Generator/Motor (양수발전소 발전-전동기 운전중 감시 시스템의 개발)

  • 김희동;주영호
    • The Transactions of the Korean Institute of Electrical Engineers C
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    • v.53 no.3
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    • pp.168-174
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    • 2004
  • On-line monitoring system(OMS) has been developed for the pumped storage generator/motor The OMS is applied to diagnosis of the PD(partial discharge) activity of stator insulation, the shorted-turn of rotor winding and the variation of the air-gap between stator and rotor. The OMS consists of DAS(data acquisition system), main server system, gateway and display PC. The DAS measures the PD, the shorted-turn and air-gap from three sensors installed on the generator/motor. The gateway controls the data which sent by DAS. The main server system saves the data, analyzes the data and conducts the diagnostic algorithm. The display PC shows the diagnostic results of partial discharge, shorted-turn and air-gap. Field tests were conducted using PDA(partial discharge analyzer). The results of the OMS and PDA measurements can be directly correlated with normalized quantity number(NQN), PD magnitude(Qm) and PD pattern.

Numerical Analysis for Stefan Problem in Mold-Casting with Air-Gap Resistance (주형/주물 접촉면에서의 접촉열저항을 고려한 상변화문제에 관한 연구)

  • 여문수;손병진;이관수
    • Transactions of the Korean Society of Mechanical Engineers
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    • v.16 no.2
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    • pp.348-355
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    • 1992
  • Casting structures and properties are determined by the solidification speed in the metal mold. The heat transfer characteristics of the interface between the mold and the casting is one of the major factors that control the solidification speed. According to Sully's research, the thermal resistance exists due to the air-gap formation at the mold-casting interface during the freezing process and the interface heat transfer coefficient is used to describe the degree of it. In this study, one-dimensional Stefan problem with air-gap resistance in the cylindrical geometry is considered and heat transfer characteristics is numerically examined. The temperature distribution and solidification speed are obtained by using the modified variable time step method. And the effects of the major parameters such as mold geometry, thermal conductivity, heat transfer coefficient and initial temperature of casting on the thermal characteristics are investigated.