• Title/Summary/Keyword: control vibration

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The Effect in the Muscle Function Following 8-Week Dead-lift training with Whole-body Vibration in Rehabilitation for Sports Players (8주간 데드리프트 운동 시 전신진동운동이 재활스포츠 선수의 근 기능 특성에 미치는 영향)

  • Oh, Ju-Hwan;Kang, Seung-Rok;Min, Jin-Young;Kwon, Tae-Kyu
    • Korean Journal of Applied Biomechanics
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    • v.25 no.3
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    • pp.343-351
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    • 2015
  • Objective : The purpose of this study was to investigate the effects in the muscle function following 8-week dead-lift training with Whole-body Vibration(WBV) in rehabilitation for sports players. Method : Twenty young sports players. Each subjects were randomly assigned to a resistance training with Whole-body vibration group(TG, n=10), a resistance training without Whole-body vibration group(CG, N=10). The measurements which physical fitness test and joint torque test were performed before the randomization and after the 4-week and 8-week. The WBV group performed the dynamic Dead-lift exercise on a vibration platform during one minute. The CG group performed the equal training without vibration. The WBV and CON group repeated 5 set and trained two times weekly for 8-weeks. Paired t-test was used to test for differences between the groups at baseline and after 4-weeks and 8-Weeks. And independent t-test was used to test for differences between the groups at TG and CG. All analyses were executed using SPSS software 18.0. The level of significance was set at p<.050. Results : Following the 8-Weeks training sessions, an increase in the back-muscle strength was found to be greater for the TG compared with the CG group(p<.05). Muscle endurance was significantly decreased after training than before training only for the CG(p<.05). Isometric Hip/Lumber Extension/Flextion measurement was found to be significantly greater for the TG compared with the CG group(p<.05). The finding indicates that WBV effects as an efficient training stimulus to enhance muscle function by facilitating neural control trail. Following muscle activation in motor unit synchronization of the co-contraction of the muscles. Conclusion : The results imply that the WBV training may have enhanced muscle function in rehabilitation for sports players.

A Study on the Passive Vibration Control of Large Scale Solar Array with High Damping Yoke Structure (고댐핑 요크 구조 적용 대형 태양전지판의 수동형 제진에 관한 연구)

  • Park, Jae-Hyeon;Park, Yeon-Hyeok;Park, Sung-Woo;Kang, Soo-Jin;Oh, Hyun-Ung
    • Journal of Aerospace System Engineering
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    • v.16 no.5
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    • pp.1-7
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    • 2022
  • Recently, satellites equipped with high-performance electronics have required higher power consumption because of the advancement of satellite missions. For this reason, the size of the solar panel is gradually increasing to meet the required power budget. Increasing the size and weight of the solar panel is one of the factors that induce the elastic vibration of the flexible solar panel during the highly agile maneuvering of the satellite or the mode of vibration coupling to the satellite or the mode of vibration coupling to the micro-jitter from the on-board appendages. Previously, an additional damper system was applied to reduce the elastic vibration of the solar panel, but the increase in size and mass of system was inevitable. In this study, to overcome the abovementioned limitations, we proposed a high -damping yoke structure consisting of a superplastic SMA(Shape Memory Alloy) laminating a thin FR4 layer with viscoelastic tape on both sides. Therefore, this advantage contributes to system simplicity by reducing vibrations with small volume and mass without additional system. The effectiveness of the proposed superelastic SMA multilayer solar panel yoke was validated through free vibration testing and temperature testing using a solar panel dummy.

Evaluation of Vertical Vibration Performance of Tridimensional Hybrid Isolation System for Traffic Loads (교통하중에 대한 3차원 하이브리드 면진시스템의 수직 진동성능 평가)

  • Yonghun Lee;Sang-Hyun Lee;Moo-Won Hur
    • Journal of the Korea institute for structural maintenance and inspection
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    • v.28 no.1
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    • pp.70-81
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    • 2024
  • In this study, Tridimensional Hybrid Isolation System(THIS) was proposed as a vibration isolator for traffic loads, combining vertical and horizontal isolation systems. Its efficacy in improving serviceability for vertical vibration was analytically evaluated. Firstly, for the analysis, the major vibration modes of the existing apartment were identified through eigenvalue analysis for the system and pulse response analysis for the bedroom slab using commercial structural analysis software. Subsequently, a 16-story model with horizontal, vertical and rotational degrees of freedom for each slab was numerically organized to represent the achieved modes. The dynamic analysis for the measured acceleration from an adjacent ground to high-speed railway was performed by state-space equations with the stiffness and damping ratio of THIS as variables. The result indicated that as the vertical period ratio increased, the threshold period ratio where the slab response started to be suppressed varied. Specifically, when the period ratio is greater than or equal to 5, the acceleration levels of all slabs decreased to approximately 70% or less compared to the non-isolated condition. On the other hand, it was ascertained that the influence of damping ratios on the response control of THIS is inconsequential in the analysis. Finally, the improvement in vertical vibration performance of THIS was evaluated according to design guidelines for floor vibration of AIJ, SCI and AISC. It was confirmed that, after the application of THIS, the residential performance criteria were met, whereas the non-isolated structure failed to satisfy them.

Study on comparison with electronic detonation blasting and non-electric detonation blasting (터널굴착 시 전자뇌관과 비전기뇌관 발파에 관한 비교 연구)

  • Yoon, Ji-Sun;Lim, Su-Hwan;Lee, Jin-Moo;Bae, Sang-Hoon
    • Journal of Korean Tunnelling and Underground Space Association
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    • v.10 no.2
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    • pp.185-191
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    • 2008
  • Today, Large and bigger underground construction are increased. In this study, Blating used electronic detonation (OBM Method) and non-electric detonation are carried out. Through comparison with two method, reduction of vibration and noise and efficiency of construction are investigated. As a result of this study, using electronic detonation is shown that it can control lower vibration and noise level, and better HCF, mucfile, advance rate and fragmentation.

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Approximate solution for a building installed with a friction damper : revisited and new result (마찰감쇠기가 설치된 건물 응답의 근사해 : 재 고찰 및 새로운 결과)

  • Min, Kyung-Won;Seong, Ji-Young;Lee, Sung-Kyung
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2009.10a
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    • pp.850-854
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    • 2009
  • Approximate analysis for a building installed with a friction damper is revisited to get insight of its dynamic behavior. Energy balance equation is used to have a closed analytical form solution of dynamic magnification factor (DMF) for the building with combined viscous and friction damping. It is found out that DMF is dependent on friction force ratio and resonance frequency. Linear transfer function from input external force to output building displacement is obtained by simplifying DMF equation. Root mean square of building displacement is derived under earthquake-like random excitation. Finally, design of friction damper is proposed by processing target control ratio, damping ratio factor, and friction force in sequence.

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System Identification of Building Structure using Subspace Identification Method (부분공간법에 의한 건축구조물의 동특성 식별)

  • Bae, Gi-Hwan
    • Journal of Korean Association for Spatial Structures
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    • v.3 no.4 s.10
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    • pp.53-58
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    • 2003
  • In order to control seismic responses of building structures effectively and stably, it is very important to estimate the dynamic characteristics of target structure exactly based on input-output signal data. In this paper, it is shown that Subspace Identification Method is able to be applied effectively to system identification of building structures. To verify the efficiency of Subspace Identification Method, the vibration experiments were conducted on a specimen structure which is a 5-storied building structure model consisted of H-shaped steel beam, and the simulated seismic responses of the identified structure model were compared with the observed ones under the same excitation. It was observed that the experimental results coincided with the analyzed ones proposed in this paper.

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A Study on the Pulsation Pressure Reduction for the Hydraulic System of Medium-Large Excavator (중대형 굴삭기 유압시스템의 압력 맥동 저감 연구)

  • Kim, Young-Hyun;Joo, Won-Ho
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2010.10a
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    • pp.421-426
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    • 2010
  • With hydraulic noise test facility, a variety of tests were performed to investigate the pulsation pressure generation mechanism and its transmission characteristics and to derive the noise control methodology. Many experiments were carried out by changing average pressure, flow rate, pump speed, hose length and MCV spool condition. From the test results, the correlations between pulsation pressure and other design parameters, such as static pressure, flow rate and MCV spool opening area and length of hose, were found out. And also each contribution factors were evaluated from the regression analysis. By changing hose length, the pulsation pressure resonance phenomenon was investigated. In order to find out the pulsation pressure reduction measures pulsation pressure analysis, such as pulsation pressure of hydraulic pump itself and pulsation pressure of hydraulic system, by using AMESim were studied. In addition hydraulic silencer was developed based on the Helmholtz resonator. And its performance was evaluated by installing the silencer at the excavator.

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Controlling a Reflection and Transmission of a Sound Using Acoustic Impedance Control (능동 임피던스 제어를 통한 소음의 반사, 투과 특성 제어)

  • Min, Dong-Ki;Oh, Ha-Young;Park, Jun-Hong
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2010.10a
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    • pp.297-297
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    • 2010
  • 이 논문에서는 음향 임피던스를 제어하는 능동형 소음 제어 방법을 연구하였다. 음향 임피던스 제어는 기존의 적응 제어 알고리즘 대신 임피던스의 크기 및 위상 최적화를 통하여 닫힌 관의 끝단에 음파의 반사를 최소화 하는 임피던스를 계산하고 제어함으로써 소음을 저감시킨다. 그리고 음향 임피던스 제어 방법을 끝단이 개방되어 있고, 중앙에 스피커가 있는 관에 적용시킨다. 이 경우에는 개방된 음장에서 음향 전달이 최소화하기 위한 임피던스를 계산하고, 음향 임피던스 제어를 통한 소음 저감을 확인한다. 이를 위해 스피커, 마이크로폰, 진동측정용 레이저 바이브로미터, 그리고 능동 소음 제어 하드웨어로 구성된 시스템을 구축하고 검증하였다.

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Deterministic Nonlinear Control of Two-Link Flexible Arm (2관절 유연한 로봇 팔에 대한 비선형 제어)

  • Han, Jong-Kil;Son, Yong-Su
    • The Journal of the Korea institute of electronic communication sciences
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    • v.4 no.3
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    • pp.236-242
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    • 2009
  • When two-link flexible arm is rotated about an joint axis, transverse vibration may occur. In this paper, vibration dynamics of flexible robot arm is modeled by using Bernoulli-Euler beam theory and Lagrange equation. Using the fact that matrix $\dot{D}$-2C is skew symmetric, new controllers which have a simplified structure with less computational burden is proposed. Lyapunov stability theory is applied to achieve a stable deterministic nonlinear controller for the regulation of joint angle.

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Fuzzy Controller of Three-Inertia Resonance System designed by Differential Evolution

  • Ikeda, Hidehiro;Hanamoto, Tsuyoshi
    • Journal of international Conference on Electrical Machines and Systems
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    • v.3 no.2
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    • pp.184-189
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    • 2014
  • In this paper, a new design method of vibration suppression controller for multi-inertia (especially, 3-ineritia) resonance systems is proposed. The controller consists of a digital fuzzy controller for speed loop and a digital PI controller for current minor loop. The three scaling factor of the fuzzy controller and two PI controller gains are determined by Differential Evolution (DE). The DE is one of optimization techniques and a kind of evolutionary computation technique. In this paper, we have applied the DE/rand/1/bin strategy to design the optimal controller parameters. Comparing with the conventional design algorithm, the proposed method is able to shorten the time of the controller design to a large extent and to obtain accurate results. Finally, we confirmed the effectiveness of the proposal method by the computer simulations.