• 한국산학기술학회논문지
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• 제14권5호
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• pp.2092-2099
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• 2013

현재 광디스크 드라이브는 오랜 기간 지속된 산업계의 데이터 전송률 경쟁을 통하여 10,000 rpm 이상의 고속으로 구동되고 있다. 고속 구동은 필연적으로 시스템의 진동을 유발하여 픽업의 데이터 읽기/쓰기 서보 제어에 외란을 야기하는데, 통상 진동외란은 방진고무를 통한 진동의 절연 및 서보 제어의 강인성 개선을 통해 해결되고 있다. 본 연구에서는 산업계에서 일상으로 이루어지는 광디스크 드라이브 시스템의 동특성 개선에서 한걸음 더 나아가 광디스크의 동특성을 개선하는데 주목하였다. 이를 위하여 사출성형 공정해석을 수행하여 공정 조건(유량, 사출온도)이 잔류응력에 미치는 영향을 조사하였고, 이 잔류응력의 변화가 광디스크의 진동 모드 및 임계속도 즉, 동특성에 미치는 영향을 모달해석을 통해 살펴보았다. 이러한 일련의 과정을 통해 사출성형 시 발생하는 광디스크의 잔류응력을 제어하여 광디스크의 임계속도를 잔류응력이 없는 경우 대비 약 14.4% 높일 수 있음을 확인하였다.

• 대한전기학회논문지:전기물성ㆍ응용부문C
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• 제52권11호
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• pp.516-520
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• 2003

A novel dual beam heterodyne Laser Doppler Vibrometer (LDV) in conjunction with FM demodulators, which utilizes a residual beam to eliminate the perturbationdue due to the vibrometer body vibration without any external reference surface, has been developed. Residual laser beam from the beam splitter is used to pick up the vibration of damper, which is mounted in the vibrometer, and combined with reference beam at the photodetector. The output signal of this detector and main signal are processed to extract the object vibration, using a least mean square adaptive algorithm. It is shown experimentally that the body vibration of 1-5 Hz can be effectively removed from the measured signal using DSP technology to extract unperturbed 100 Hz original signal.

• 제어로봇시스템학회논문지
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• 제6권12호
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• pp.1045-1052
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• 2000

In this paper, we propose a method to apply the Input Shaping Technique (IST) to multi-input multi-output (MIMO) systems. In MIMO systems, there is a high possibility of multi-mode residual vibration. The IST filter designed for this multi mode may need a longer time to suppress the residual vibration. Previous works prove that we can shorten the time lag by using negative sequence. This negative sequence, however, causes another problem - it requires excessive control input. In this paper, we provide a remedy to reduce the size of control input by limiting the reference input by limiting the reference input and its derivative. The result of simulations and experiments on a 2 link flexible arm confirmed the effectiveness of the proposed method.

• 한국정밀공학회지
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• 제24권11호
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• pp.91-100
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• 2007

Many manufacturing devices must execute motions as quickly as possible to achieve profitable high-volume production. Most of them have devices having flexibility and a time delay of one sampling is added to the plants when they are controlled by fast discrete controllers, which brings about non-minimum phase zeros. This paper develops a control strategy that combines feedforward and feedback control with command shaping for such devices. First, the feedback controller is designed to increase damping and eliminate steady-state error. Next, the feedforward controller is designed to speed up the transient response. Finally, an appropriate reference profile is generated using command-shaping techniques to ensure fast point-to-point motions with minimum residual vibration. The particular focus of the paper is to understand the interactions between these individual control components. The resulting control strategy is demonstrated on a model of a high-speed semiconductor manufacturing machine.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2006년도 춘계학술대회논문집
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• pp.634-639
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• 2006

Active control method is applied to a flexible beam excited by a shock impulse in order to reduce the residual vibrations after the shock event. It is assumed that the shock input can be measured and is always occurred on the same point of the beam. If the system is well identified and the corresponding inverse system is designed reliably, it has shown that a very simple feed-forward active control method may be applied to suppress the residual vibrations without using error sensors and adaptive algorithm. Both numerical simulations and experimental results show a promising possibility of applying to a practical problem. Also, the performance of the method is examined by considering various practical aspects : shock duration, shock magnitude, and control point.

• 한국소음진동공학회논문집
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• 제16권6호
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• pp.651-657
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• 2006

Active control method is applied to a flexible beam excited by a shock impulse in order to reduce the residual vibrations after the shock event. It is assumed that the shock input can be measured and is always occurred on the same point of the beam. If the system is well identified and the corresponding inverse system is designed reliably, it has shown that a very simple feed-forward active control method may be applied to suppress the residual vibrations without using error sensors and adaptive algorithm. Both numerical simulations and experimental results show a promising Possibility of applying to a practical problem. Also, the performance of the method is examined by considering various practical aspects : shock duration, shock magnitude, and control point.

• Steel and Composite Structures
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• 제4권5호
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• pp.355-365
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• 2004

A new reduction method of residual stress in welding joint is proposed where welded metals are shaken during welding. By an experiment using a small shaker, it can be shown that tensile residual stress near the bead is significantly reduced. Since tensile residual stress on the surface degrades fatigue strength for cumulative damage, the proposed method is effective to reduction of residual stress of welded joints. The effectiveness of the proposed method is demonstrated by the response analysis using one mass model with nonlinear springs.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2001년도 춘계학술대회논문집
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• pp.811-818
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• 2001

ISO 11342 classifies flexible rotors in accordance with their balancing requirements and establishes methods of assessment of residual unbalance. This International Standard also shows how criteria for use in the balancing facility may be derived from either vibration limits specified for the assembled and installed machine or unbalance limits specified for the rotor. If such limits are not available, this standard shows how they may be derived from ISO 10816 and ISO 7919 if desired in terms of vibration, or from ISO 1940- 1 if desired in terms of permissible residual balance. This International Standard also presents methods for adapting the criteria of ISO 1940- 1 to flexible rotors.

• 한국생산제조학회지
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• 제24권4호
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• pp.414-420
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• 2015

In this study, the linear quadratic Guassian loop transfer recovery (LQG/LTR) control technique was combined with an integrator and applied to an inchworm having piezoelectric actuators for precise motion tracking. The piezoelectric actuator showed nonlinear response characteristics, including hysteresis, due to its ferroelectric characteristics and the residual displacement phenomenon. This paper proposes a feedback control scheme using the LQG/LTR controller with an integrator to improve the ability to track the response to complex input signals and to suppress the phenomenon of hysteresis and residual vibration. Experimental results show that the developed feedback control system for an inchworm can track the various motion contours quickly without residual vibration or overshoot.

• Computers and Concrete
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• 제20권4호
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• pp.503-509
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• 2017

In this study, fire-damaged concrete was investigated by a nonlinear resonance vibration (NRV) technique, in order to evaluate its residual material properties. For the experiments, five cubic concrete specimens were prepared and four of them were damaged at different temperatures using a furnace. With a thermal insulator wrapped at the sides of specimen, thermal gradation was applied to the samples. According to the peak temperatures and depths of the samples, nonlinearity parameters were calculated with the NRV technique before the tendency of the parameters was evaluated. In addition, compressive strength and dynamic elastic modulus were measured for each sample and a comparison with the nonlinearity parameter was carried out. Through the experimental results, the possibility of the NRV technique as a method for evaluating residual material properties was evaluated.