• Title, Summary, Keyword: Resonance

Search Result 10,412, Processing Time 0.051 seconds

Relationship Between the Resonance Frequency and QTS for Microspeaker (마이크로스피커에서 공명진동수와 QTS 사이의 연관성)

  • Oh, Sei-Jin
    • Korean Journal of Materials Research
    • /
    • v.21 no.7
    • /
    • pp.403-409
    • /
    • 2011
  • Micro speakers are used to reproduce sound in small electric and information and communications devices, such as cellular phones, PMPs, and MP3 players. The acoustical properties and sound quality, which are changed due to the decreased size of the speaker, are often adjusted varying the type and thickness of the diaphragm. The most widely used diaphragm material is thin polymer. It was previously reported by the author of this paper that the resonance frequency of a micro speaker is changed by the type and thickness of a polymer diaphragm. In this paper, the frequency response near the resonance frequency of a micro speaker was studied as functions of the type and thickness of the polymer diaphragm. While $R_{max}$ and $R_{DC}$ were affected by the type and thickness, an analysis of the electrical impedance curve revealed that $R_o(= R_{max}/R_{DC})$ and ${\Delta}f$ were not changed. Thus, $Q_{TS}$ which was function of $R_o$, ${\Delta}f$, and the resonance frequency, is only related to the resonance frequency. The increase of the resonance frequency led to a proportional rise of $Q_{TS}$. The change of the frequency response near the resonance frequency was not dependent on the type or thickness of the polymer diaphragm, but was affected by the resonance frequency.

Analysis of the Effects According to Changes in Impedance and Electrical Equivalent Circuit Modeling of a SONAR Transducer Considering Dual Resonance (이중 공진을 고려한 소나 트랜스듀서의 전기적 등가회로 모델링 및 임피던스 변동에 따른 효과 분석)

  • Mok, Hyung-Soo;Choi, Jae-Hyuk;Han, Soo-Hee;Park, Sang-Zoon;Kim, Sung-Joo;Heo, Jun-Ki
    • The Transactions of the Korean Institute of Power Electronics
    • /
    • v.20 no.2
    • /
    • pp.144-151
    • /
    • 2015
  • The present study proposes a method for modeling a SONAR transducer with dual resonance. The Butterworth van-Dyke (BVD) model, a conventional SONAR transducer modeling method, can model only one resonance point. Hence, to address its disadvantage and to model the dual resonance, a dual resonance BVD model consisting of two serial BVD models is proposed. The two BVD models are connected in a series, and each simulate resonance at low frequency and high frequency, which allows the modeling of two resonance points. Eight elements compose the equivalent circuit by connecting the BVD models in a series, which is twice as great as that of the existing BVD model. The element value of the dual resonance BVD model is extracted by using the particle swarm optimization method. Analysis was also performed to identify the effects of changes in the value of elements that compose the equivalent circuit on the impedance characteristics of the equivalent circuit through simulation in which element values varied.

Effects of Acoustic Resonance and Volute Geometry on Phase Resonance in a Centrifugal Fan

  • Tsujimoto, Yoshinobu;Tanaka, Hiroshi;Doerfler, Peter;Yonezawa, Koichi;Suzuki, Takayuki;Makikawa, Keisuke
    • International Journal of Fluid Machinery and Systems
    • /
    • v.6 no.2
    • /
    • pp.75-86
    • /
    • 2013
  • The effects of acoustic resonance and volute geometry on phase resonance are studied theoretically and experimentally using a centrifugal fan. One dimensional theoretical model is developed taking account of the reflection from the discharge pipe end. It was found that the phase resonance occurs, even with the effects of acoustic resonance, when the rotational speed of rotor-stator interaction pattern agrees with the sound velocity. This was confirmed by experiments with and without a silencer at the discharge pipe exit. The pressure wave measurements showed that there are certain effects of the cross-sectional area change of the volute which is neglected in the one dimensional model. To clarify the effects of area change, experiments were carried out by using a ring volute with a constant area. It was demonstrated that the phase resonance occurs for both interaction modes travelling towards/away from the volute. The amplitude of travelling wave grows towards the volute exit for the modes rotating towards the volute exit, in the same direction as the impeller. However, a standing wave is developed in the volute for the modes rotating away from the volute exit in the opposite direction as the impeller, as a result of the interaction of a growing wave while travelling towards the tongue and a reflected wave away from the tongue.

Structural Studies on IRES 4-2 Domain of Foot-and-mouth Disease Virus

  • Kim, Young-Mee;Yoo, Jun-Seok;Cheong, Hae-Kap;Lee, Chul-Hyun;Cheong, Chae-Joon
    • Journal of the Korean Magnetic Resonance Society
    • /
    • v.7 no.2
    • /
    • pp.89-97
    • /
    • 2003
  • Foot-and-mouth disease virus (FMDV) belongs to the aphthovirus genus within the picornavirus which has a single copy of a positive sense RNA. The translation initiation process of FMDV occurs by a cap-independent mechanism directed by a highly structured element (∼435 nt) termed an internal ribosome entry site (IRES). We have designed and prepared FMDV 4-2 RNA (28nt) by in vitro transcription. The 2D NMR data revealed that FMDV 4-2 IRES domain RNA has a flexible loop and bulge conformation. In further study, we need to make an isotope labeled RNA sample and conduct 3D NMR experiments to completely determine the 3D structure. This study may establish a new drug design strategy to treat foot-and mouth disease.

  • PDF

A Study on the Presure Resonance with Combustion Chamber Geometry for a Spark Ignition Engine (스파크 점화기관의 연소실 형상에 따른 공진현상 해석에 관한 연구)

  • Park, Kyoung-Suk;Jang, Seok-Hyung
    • Proceedings of the KSME Conference
    • /
    • /
    • pp.890-895
    • /
    • 2001
  • Pressure resonance frequency that is caused in the combustion chamber can be interpreted to acoustic analysis. Until now the pressure resonance has been assumed and calculated to a disc type combustion chamber that neglected the combustion chamber height because the knock occurs near the TDC(top dead center). In this research FEM(fine element method) has been used to calculate the pressure resonance frequency inside the experimental engine combustion. The reduce error of the resonance frequency obtained by FEM has decreased about 50% compared to the calculation of Draper's equation. Due to the asymmetry in the shape of the combustion chamber that was neglected in Draper's equation we could find out that a new resonance frequency could be generated. To make the experimental results equal we could know that the speed of sound that satisfies Draper's equation was selected 13% higher than all the pent-roof type combustion considered.

  • PDF

Nondestructive Inspection Method of Composite Laminated Plates by Holographic Interferometry (홀로그래피 간섭계를 이용한 복합적층판의 결함측정)

  • 김석중;김재형;박현철
    • Transactions of the Korean Society of Mechanical Engineers
    • /
    • v.18 no.12
    • /
    • pp.3202-3218
    • /
    • 1994
  • Mode shapes and natural frequencies of vibrating laminated composite plates are taken using real-time and time-average holographic interferometry. Debonds and delamination in the laminated plates are measured nondestructively. During holographic testing of composite plates, it has been found that the conditions for the local resonance in debonds are strongly dependent on the frequency of excitation. A membrane resonance model was proposed to describe this behavior. Relations between characteristic length according to the size, shape of debonds and membrane resonance frequency are presented. Several experiments were performed to verify the membrane resonance model. The agreements between the predicted excitation frequency and the observed resonance frequency are good. The experimental results show that higher stresses and strains due to local resonance lead to the debond detection.

Energy Calibration for Neutron Capture Resonance of Natural Sm by Using 46-MeV Electron Linear Accelerator

  • Lee, Jae-Hong;Lee, Sam-Yol
    • Journal of the Korean Society of Radiology
    • /
    • v.1 no.2
    • /
    • pp.31-35
    • /
    • 2007
  • Energy calibration is important to identify accurate neutron capture resonance energy in the neutron TOF (Time-of-Flight) experiment. In present study, the accurate neutron capture resonance energies of natural Sm were measured by using a 46-MeV electron linear accelerator (linac) at the Research Reactor Institute, Kyoto University(KURRI). The BGO spectrometer were adopted for measurement the prompt capture gamma-ray of the sample. To obtain energy calibration curve, resonance energy of a gold sample used as standard resonance energy Mughabghab's data (From neutron resonance parameters data). Previous data (by Mughabghab) of natural Sm sample have been compared with the present result.

  • PDF

Fluid-structure interaction analysis of micromechanical resonance sensor (마이크로기계 공진 센서의 유체-구조물 상호 작용 해석)

  • Kang, In-Goo;Shin, Yoon-Hyuk;Yim, Hong-Jae;Lim, Si-Hyung
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
    • /
    • /
    • pp.309-313
    • /
    • 2009
  • A micromechanical resonance sensor detects the resonance frequency shift due to mass or adsorption induced surface stress change during molecular adsorption or interaction on its surface. The resonance sensor is surrounded by gas or liquid solution during operation. To study the resonance shift phenomena depending on its surrounding environment, fluid-structure interaction of the resonance sensor has been analyzed for the different fluid environment and boundary conditions using finite element analysis.

  • PDF

Resonance avoidance and Safety Evaluation of Vertical Pump (입형펌프의 공진회피와 안전성 평가)

  • Jeong, Wooyoung;Song, Jindae
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
    • /
    • /
    • pp.698-702
    • /
    • 2013
  • This paper considers the vertical pumps resonance and soundness. Normally large vertical pump's rotating speed is low, so the low natural mode can make a resonance on the motor and motor stand assembly. The pump resonance makes a very high vibration and trouble on the pump systems. Thus to avoid pump resonance when the pump is on the resonance region, we give the added mass method and evaluate the structure soundness by computer simulation and test on the site. Furthermore we evaluate the modal sensitivity and expect running conditions by the using ISO10814.

  • PDF

A Wide-band Multi-layer Antenna Design using Double Resonance (이중공진을 사용한 적층기판용 광대역 안테나 설계)

  • Lee, Kook-Joo;Zhang, Mei-Shan;Lee, Jung-Aun;Han, Myeong-Woo;Kim, Moon-Il
    • The Transactions of The Korean Institute of Electrical Engineers
    • /
    • v.60 no.2
    • /
    • pp.431-434
    • /
    • 2011
  • In this paper, bandwidth enhanced design of dielectric resonator antenna fabricated in multi-layer substrate is introduced. The proposed dielectric resonator antenna is operating with fundamental TE101 mode and higher-order TM111 mode. Each resonance frequency is dependent on resonator dimensions. As increasing the height of radiating aperture, the higher-order TM111 mode resonance frequency approach the fundamental TE101 mode resonance frequency and the antenna bandwidth increase by double resonance. Three different aperture height size antennas that operated at 7GHz are fabricated in FR4 multi-layer substrate. Measured 10 dB matching bandwidth is 8 percent for single resonace antenna and 18 percent for double resonance antenna.