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이종국(Jong-Kuk Lee),송태성(Tae-Seong Song),강정민(Jeong-Min Kang),송덕기(Deok-Ki Song),권준범(Jun-Beom Kwon),서중보(Joong-Bo Seo),오화석(Hwa-Suk Oh),전동익(Dong-Ik Cheon),홍영곤(Young-Gon Hong),이준용(Jun-Yong Lee) 한국항공우주학회 2020 韓國航空宇宙學會誌 Vol.48 No.11
‘제어모멘트자이로’ 내 모멘텀 휠의 속도가 커지게 되면 질량 불균형으로 인해 발생하는 의도하지 않은 힘과 토크가 증가하게 된다. 그리고 이러한 힘과 토크는 위성을 통해 촬영된 SAR 영상의 떨림을 유발하기 때문에 최소화하여야 한다. 본 논문에서는 ‘제어모멘트자이로’ 내 모멘텀 휠의 질량불균형(정적질량불균형과 커플질량불균형)의 보상에 대해서 기술하였다. 우선 M&S를 통해 질량불균형의 발생에 따른 질량중심점에서 발생하는 힘과 토크의 발생을 예측하였다. 두 번째로는 힘과 토크의 측정 지점을 회전 중심에서 이격하였을 때, 질량불균형에 따른 힘과 토크의 발생을 예측하였다. 세 번째로는 질량불균형으로 인해 발생하는 힘과 토크를 측정하기 위한 장치 구성에 대해 기술하였으며, 네 번째로는 실제 구동하는 모멘텀 휠에 지정된 질량을 추가하였을 때, 힘과 토크의 변화량을 M&S와 비교하여 기술하였다. 그리고 마지막으로 이러한 분석을 바탕으로 24Nm급 ‘제어모멘트자이로’를 대기모드로 구동하였을 때의 보정 전과 후의 힘과 토크 변화를 기술하였다. Raising the speed of the momentum wheel in the CMG increases the unintended force and torque caused by mass imbalance. This unintended force and torque should be minimized to get the better quality of satellite SAR image because they lead to the vibration of the output image. This paper shows the works on compensating the static imbalance and couple mass imbalance in the CMG wheel. First, the force and torque at the center of mass generated by the mass imbalance were predicted through M&S analysis. Second, the force and torque were estimated similarly through the M&S analysis when the measurement point was moved from the rotation center. Third, the measurement configuration for the force and torque by the mass imbalance was described. Fourth, the change of the force and torque by adding the specified mass to the momentum wheel was observed after comparing the measurements with the results of the M&S. And finally, the effect of the compensation was analyzed by comparing the force and torque before and after the correction while 24Nm class CMG was running in the standby mode.
풍력발전기 블레이드 상태 모니터링을 위한 질량 불균형 감지기법
이종원 한국구조물진단유지관리공학회 2011 한국구조물진단유지관리공학회 논문집 Vol.15 No.1
본 연구에서는 효과적인 풍력발전기 블레이드의 상태 모니터링을 위하여 대표적 손상형태 중 하나인 로터의 질량 불균형으로 인한 이상상태를 감지할 수 있는 기법을 제안하였다. 이를 위하여 수평축 3-블레이드 풍력발전기를 대상으로, 블레이드 1개의 질량을 증가시키면서 로터의 질량 불균형 조건을 구현한 후 전체 풍력발전기에 대한 동력학 시뮬레이션을 수행하였다. 질량불균형이 발생하면 부가질량에 의한 원심력에 의하여 나셀의 로터 회전축에 대한 횡방향 진동이 발생하고, 부가 질량의 크기가커질수록 나셀 횡방향 진동의 진폭이 거의 선형적으로 증가함을 알 수 있었다. A method to detect rotor mass imbalance, which is one of the typical faults of wind turbine, is presented for effective condition monitoring of wind turbine. Dynamic analysis for a three-bladed horizontal-axis wind turbine was carried out with adding mass to a blade for inflicting the rotor mass imbalance. It has been found that the added mass induce a resulting centrifugal force to nacelle and this leads to a transverse (relative to the rotor axis) oscillation of the nacelle. It has been also found that the amplitude of the oscillation is almost linearly increased as the added mass is increased.
회전 불균형 질량이 Front Axle 진동특성에 미치는 영향 및 저감 방안
박태원(Taewone Park),김기주(Kee Joo Kim),최병익(Byung-Ik Choi),성창원(Chang Won Sung),김상식(Sangshik Kim),김헌영(Heon Young Kim) 한국자동차공학회 2007 한국 자동차공학회논문집 Vol.15 No.6
The purpose of this study is to investigate the effect of rotating unbalance mass on vibration characteristics of the front axle. The power-train systemof the vehicle is composed of several rotating parts. These component parts should be properly balanced by the balancing machine, however,sometimes these have the unbalance mass which causes the critical vibration in the vehicle. Therefore, this study suggests the vibration improvement method based on reducing the unbalance mass through changing the assembly type between the companion flange and the constant velocity joints. In addition, the way to increase the inertia moment of the companion flange was proposed.
볼 베어링과 스퀴즈 필름 댐퍼로 지지되는 차량용 터보차저의 회전체동역학 해석: 스퀴즈 필름 댐퍼 설계 인자와 회전체 불균형 질량의 영향
김규만,류근 한국트라이볼로지학회 2018 한국트라이볼로지학회지 (Tribol. Lubr.) Vol.34 No.1
Modern high-performance automotive turbochargers (TCs) implement ceramic hybrid angular contact ball bearings in series with squeeze film dampers (SFDs) to enhance transient responses, thereby reducing the overall emission levels. The current study predicts the rotordynamic responses of the commercial automotive TCs (compressor wheel diameter = ~53 mm, turbine wheel diameter = ~43 mm, and shaft diameter at the bearing locations = ~7 mm) supported on ball bearings and SFDs for various design parameters of SFDs, including radial clearance, axial length, lubricant viscosity, and rotor imbalance conditions (i.e., amplitudes and phase angles) while increasing rotor speed up to 150 krpm. This study validates the predictive rotor finite element model against measurements of mass, polar and transverse moments of inertia, and free-free mode natural frequencies and mode shapes. A nonlinear rotordynamic model integrates nonlinear force coefficients of SFDs to calculate the transient responses of the TC rotor-bearing system. The predicted results show that SFD radial clearances, as well as phase angles of rotor imbalances, have the paramount effect on the dynamic responses of TC shaft motions.
자기베어링을 이용한 잔류질량불균형이 존재하는 초고속 회전체의 온라인 밸런싱
송상호,박영진,정성종 한국공작기계학회 1998 한국생산제조학회지 Vol.7 No.1
In order to minimize vibration problems of rotating machinery rotors have been assembled through balancing machines. Since perfect balancing is impossible, residual unbalances cause serious vibration while ghe rotor is in high speed region. To minimize unbalance effects of magnetic bearing systems(AMB) during rotation on-line balancing methodology was studied. Unbalances were considered as disturbances of the system. The disturbance observer was used to estimate unbalance forces from measurable state and input variables. Balancing inputs computed according to LQR and outputs of the observer were applied to eliminate unbalances during high speed rotation of the AMB. The effectiveness of he on-line balancing was verified through numerical simulations.
2-축 자이로 안정화 김발 시스템의 외란보상 앞먹임 제어를 위한 실험적 2-축 외란 동시 식별
여성민,강민식,Yeo, Sung Min,Kang, Min Sig 한국군사과학기술학회 2018 한국군사과학기술학회지 Vol.21 No.4
This paper concerns on stabilization control of a gyro-stabilized 2-axes gimbal system which is mounted on a moving vehicles such as automobiles, armored vehicles, ships, flying vehicles, etc. A target image acquisition system is attached on the inner gimbal, and the gimbal systems are required to retain high stabilization accuracy in the absolute coordinate in order to provide fine target image while vehicle is moving. The stabilization control performance is hardly depended upon disturbance rejection ability of control, and disturbance feedforward compensation is effective because feedforward compensation reduce the amount of disturbance before the disturbance disturbs the systems. This paper suggests an experimental method which can estimate system parameters and disturbance torques by using 3-axes accelerometer mounted on the inner gimbal. Furthermore, a simple disturbance identification method which can be applied to any slanted base conditions has been suggested to identify mass unbalance vector and friction torques of each gimbal simultaneously. By using the estimated parameters, a feedforward compensation has been applied to the gyro-stabilized 2-axes gimbal system. The experimental results showed that the feedforward compensation based on the identification method suggested is effective to improve stabilization performances.
최은석,진원종,곽종원,박성용,강재윤,김영진,김병석 한국철도학회 2001 한국철도학회논문집 Vol.4 No.1
The dynamic characteristics such as natural frequency, mode shape and damping ratio are most important parameters in the high-speed railway bridges rather than general roadway bridges. Also, the need to know the dynamic behavior of bridges greatly increased in recent years. In the early of 1990s, to design the high-speed railway bridges, damping ratio recommended in general code was 2.5~7.5%. However, these values were not applied in all cases. Therefore, obtaining the damping value of specific structures is important to get the correct variable for design of high-speed railway bridges. The purpose of this study is mainly to obtain the damping ratio of high-speed railway bridges. The average damping ratio of high-speed railway bridges evaluated from a field test is about 2.4%.