• Title/Summary/Keyword: resonant motion

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Electromagnetic Microactuators with the Electroplated Planar Coil Driven by Radial Magnetic Field (방사형 자기장 내의 전기도금된 평면코일을 이용한 전자기형 마이크로 액추에이터)

  • Ryu, Ji-Cheol;Gang, Tae-Gu;Jo, Yeong-Ho
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.25 no.1
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    • pp.16-24
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    • 2001
  • This paper presents an electromagnetic microactuator using the copper coil electroplated on the p+silicon diaphragm. The microactuator generates a vertical motion of the diaphragm using the radial direction, we propose a new actuator structure with twin magnets. The microactuator field in the radial direction, we propose a new actuator structure with twin magnets. The microactator shows a values of resonant frequency and quality factor in the ranges of 10.51${\pm}$0.22kHz and 46.6${\pm}$3.3, respectively. The twin magnet microactuator generates the maximum peak-to-peak amplitude of 4.4$\mu\textrm{m}$ for the AC rms current of 26.8mA, showing 2.4 times larger amplitude than the single magnet microactuator.

Group-Bounded Long Waves and Harbor Oscillation (항만(港灣) 및 해안공학파군(海岸工學波群)에 따른 장주기파(長週期波)와 항만(港灣)의 진동(振動))

  • Lee, Cheol Eung;Lee, Kil Seong
    • KSCE Journal of Civil and Environmental Engineering Research
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    • v.14 no.3
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    • pp.607-618
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    • 1994
  • Effects of wave grouping on the harbor oscillation are studied in order to clarify the energy source of harbor resonance. The resonant periods of Donghae harbor and Imwon harbor are calculated using the boundary integral equation method. Also, the periods of the group-bounded long waves due to the irregular wave group are calculated using the theory developed in this study. Analyzing from the view point of period, it is concluded that the group-bounded long waves due to the irregular wave group can cause resonance in small harbors such as fishery harbors, and heavy ship motion in large harbors such as industrial ones.

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Stability Analysis of Cracked Cantilever Beam with Tip Mass and Follower Force (끝단질량과 종동력을 가진 크랙 외팔 보의 안정성 해석)

  • Son, In-Soo;Yoon, Han-Ik;Ahn, Tae-Su
    • Transactions of the Korean Society for Noise and Vibration Engineering
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    • v.17 no.7 s.124
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    • pp.605-610
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    • 2007
  • In this paper a dynamic behavior(natural frequency) of a cracked cantilever beam subjected to follower force is presented. In addition, an analysis of the flutter and buckling instability of a cracked cantilever beam subjected to a follower compressive load is presented. Based on the Euler-Bernoulli beam theory, the equation of motion can be constructed by using the Lagrange's equation. The vibration analysis on such cracked beam is conducted to identify the critical follower force for flutter instability based on the variation of the first two resonant frequencies of the beam. Besides, the effect of the crack's intensity and location on the flutter follower force is studied. The crack section is represented by a local flexibility matrix connecting two undamaged beam segments. The crack is assumed to be in the first mode of fracture and to be always opened during the vibrations.

Dynamic Analysis of Switchable Hydraulic Engine Mount with an Inertia Track and a Decoupler (유체봉입 마운트의 유로 조절에 따른 진동감쇠 성능향상)

  • Ahn, Young Kong
    • Transactions of the Korean Society for Noise and Vibration Engineering
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    • v.27 no.1
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    • pp.80-86
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    • 2017
  • This paper describes switching method of the cross-sectional area of the fluid passage way to improve the performance of a hydraulic engine mount with an inertia track and a decoupler. The mount has nonlinear dynamic characteristics depending on the vibrational frequency and amplitude. For the convenience of analysis, two linear motion equations were derived on the basis of the mechanical model according to the low-and high-frequencies. The properties of the transmissibility and dynamic stiffness derived from the equations were investigated according to switching the cross-sectional area of the inertia track and decoupler. Switching method of the cross-sectional area can be derived from the transmissibility plot. In comparison between transmissibility of passive and switchable mounts with an inertia track and a decoupler, the performance of the switchable mount is improved greatly than the passive mount. The resonant peak is remarkably reduced in the high frequency region.

Experiment and Simulation Study on Performance Evaluation and Design of Fin-Stabilizer (핀 안정기 설계와 성능평가를 위한 모형시험과 시뮬레이션 연구)

  • Cho Seok-Kyu;Hong Sa-Young;Jang Taek-Su
    • Journal of the Society of Naval Architects of Korea
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    • v.41 no.6
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    • pp.1-7
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    • 2004
  • Recently, very large container ships are emerging as shipment of containers is expected to rapidly increase near future. A possibility of roll resonant motion in a seaway is expected to noticeably increase for large container ships of which capacity ranges 8,000 to 15,000 TEU due to relatively wide breadth and shallow draft comparing to conventional container ships. In this paper, a design and performance evaluation of a fin stabilizer for a 9,000 TEU container ship is carried out. The weak opposed control concept is adopted for the design. Time domain simulations and model tests are performed for performance evaluation. The design prediction, the model tests and the simulations show generally good agreements.

Passive Suppression of Nonlinear Panel Flutter Using Piezoelectric Materials with Resonant Circuit

  • Moon, Seong-Hwan;Yun, Chul-Yong;Kim, Seung-Jo
    • Journal of Mechanical Science and Technology
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    • v.16 no.1
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    • pp.1-12
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    • 2002
  • In this study, a passive suppression scheme for nonlinear flutter problem of composite panel, which is believed to be more reliable than the active control methods in practical operations, is proposed. This scheme utilizes a piezoelectric inductor-resistor series shunt circuit. The finite element equations of motion for an electromechanically coupled system is derived by applying the Hamilton\\`s principle. The aerodynamic theory adopted for the present study is based on the quasi-steady piston theory, and von-barman nonlinear strain-displacement relation is also applied. The passive suppression results for nonlinear panel flutter are obtained in the time domain using the Newmark-$\beta$ method. To achieve the best damping effect, optimal shape and location of fille piezoceramic (PZT) patches are determined by using genetic algorithms. The effects of passive suppression are investigated by employing in turn one shunt circuit and two independent shunt circuits. Feasibility studies show that two independent inductor-resistor shunt circuits suppresses flutter more effectively than a single shunt circuit. The results clearly demonstrate that the passive damping scheme that uses piezoelectric shunt circuit can effectively attenuate the flutter.

Development and Experiment of a Linear Array Acoustic Lens with 31 Microphones (마이크로폰 31개로 이루어진 선형배열 음향렌즈의 구성과 실험)

  • Hyun, Seok-Bong;Min, Dong-Hyun;Kim, Su-Young
    • The Journal of the Acoustical Society of Korea
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    • v.13 no.5
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    • pp.15-23
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    • 1994
  • We developed an electronic lens for acoustic imaging systems, which is linear array with 31 microphones equally spaced with distance 34mm. Resonant frequency fo receiver circuit coupled to microphone is 20 kHz. We arranged 16 microphones horizontally and 15 microphones vertically, so that the array allows us to obtain a 2 dimensional angle of source, and to track the motion of source in real time. Due to the problem of aliasing in discrete Fourier Transfrom, the maximum observable angle of the lens is limited to 15${\circ}$. We also employed quadrature phase detection scheme to adjust the focus. We have tested the acoustic lens with a personal computer in an anechoic room and obtained the results agreed with the acoustic imaging theory.

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Experimental Study on Sloshing in Rectangular Tank with Vertical Porous Baffle (투과성 내부재가 설치된 사각형 탱크내의 슬로싱 현상에 대한 실험적 연구)

  • Hyeon, Jong-Wu;Cho, IL-Hyoung
    • Journal of Ocean Engineering and Technology
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    • v.29 no.4
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    • pp.291-299
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    • 2015
  • A variety of inner baffles are often installed to reduce liquid sloshing and prevent tank damage. In particular, a porous baffle has a distinct advantage in reducing sloshing by changing the natural periods and dissipating the wave energy in a tank. In model tests, porous baffles with five different porosities were installed vertically in a liquid tank under sway motion. The free surface elevations and pressures were measured using an image processing technique and a pressure gage for various combinations of baffle's porosity and submergence depth, and tank's amplitude and period. The experimental results were in good agreement with the analytic solutions (Cho, 2015), with the exception of a quantitative difference at resonant periods. The experimental results showed that the sloshing characteristics in a tank were closely dependent on both the porosity and submergence depth of the baffle, and the optimal porosity existed near P = 0.1275.

A Study on Dynamic Characteristics of 3-axis Actuator for the Slim Type Pick-Up (3축 구동이 가능한 Slim형 Pick-Up Actuator 개발 및 동특성 분석)

  • 박관우;서민석;홍삼열;김영중;최인호;김진용
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2002.05a
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    • pp.373-377
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    • 2002
  • In this study, we suggested a slim-type actuator that can be controlled in radial direction for compensating coma aberration in high-capacity optical storage devices. To deal successfully with narrow space in slim-type optical pick-up for notebook pc device, additional yokes for tilting motion are integrated into main yoke of the actuator. And the location of tilting coils is determined for mass-b3lancing effect to achieve optimal configuration for high driving sensitivity. We also suggested new concept of lens holder to guarantee excellent stability of control system by enhancing the gain margin at secondary resonant frequency. The concept was realized by forming damping sections in the lens holder, which prevent vibrational energy from transferring to lens. An exclusive measurement system was newly developed for fast and precise measurement of dynamic characteristics of actuators and utilized for the practical use. We hope to make good use of this system also in time to come.

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Energy and Speed Characteristics of Induction Coil-Gun (유도형 코일건의 에너지 및 속도특성 해석)

  • 장성만;김석환;한송엽;정현교
    • Journal of the Korean Magnetics Society
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    • v.2 no.1
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    • pp.69-74
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    • 1992
  • This paper describes the energy and speed characteristics of an induction coil-gun. The coil-gun has some merits that it can be easily installed and repeatedly used many times, it does not damage mechanically in the course of launch and the force exerted on the projectile is distributed uniformly. An equivalent circuit is employed for modeling the coil-gun. The circuit equations and equation of motion are then derived based on the equivalent circuit. These equations are solved numerically by using Runge-Kutta method. Finally the energy transfer ratios are obtained according to the variations of the resonant frequency of driving circuit and charging voltage of capacitors. The muzzle velocities of projectile are also obtained according to the variations of electrical conductivity and initial position of projectile, firing angle of driving circuit, charging voltage of capacitor and resistance of driving coil, respectively.

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