• Wind and Structures
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• 제16권4호
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• pp.341-354
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• 2013

This paper presents an experimental investigation concerning the peak amplitudes of oscillation of a square prism due to Vortex-Induced-Vibrations (VIV) as a function of the mass damping parameter $m^*{\zeta}$ (the so called Griffin--plot); $m^*$ and ${\zeta}$ being, respectively, the non-dimensional mass and the mechanical (structural) damping ratio. With this purpose in mind, an electromagnetic actuator has been employed to provide controlled damping. During the experiments the mass--damping parameter was in the range 0.15 < $m^*{\zeta}$ < 2.4. Experiments show that there is a value of $m^*{\zeta}$ below which VIV appears combined with galloping and the prism oscillation increases monotonically with the incoming flow velocity. For $m^*{\zeta}$ >0.3 the present experiments show a well-defined VIV phenomenon and, consequently, a Griffin-plot can be defined.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2005년도 제36회 하계학술대회 논문집 C
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• pp.2392-2394
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• 2005

This paper presents a tuneable bandstop resonator with two possible configurations, it can be used to tune its center frequency, or it can be used to tune its bandwidth. The tuneable bandstop resonator has potential application in microwave communications receivers, where it can be used to tune out interfering signals. The proposed resonator is comb actuated, where the resonator's displacement produces different values of frequency or bandwidth, this is achieved by decoupling electromagnetic energy from a main transmission line. The proposed fabrication process for the resonator is by anodic bonding pyrex glass and tow resistivity silicon, where the comb resonator structure is patterned by deep reactive ion etching (DRIE). This paper presents the resonator and actuator design in both configurations, as well as the fabrication process intended for its development.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2003년도 하계학술대회 논문집 D
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• pp.2251-2253
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• 2003

This paper is concerned with the active vibration control of flexible cantilever beam system using electromagnetic force actuator. The main objective of this paper is to propose the control algorithms and implement the experimental setups for active vibration control. Several control algorithms are proposed and implemented on the experimental setups to show their efficacy. These include a PID control design, an optimal $H_2$ control design, and a fuzzy PID control design. Effectiveness and performance of the designed controller were verified by both simulation and experiment results.

• 소음진동
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• 제2권4호
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• pp.293-304
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• 1992

Active vibration control is presented with simulation and experiment. Dynamic Data System(DDS) method is used for system modeling and this model is combined with an forecasting control technique to derive a control equation. In the experiment, on-line digital computer monitors structural vibration and calculates control input. The control input is sent to an electromagnetic actuator which cancels the structural vibration. Experiment is performed first with a simple beam setup to demonstrate the effetiveness of this method. This method is then applied to a color laser printer to actively modify the structure. The beam experiment showed vibration reduction of over 60% with one-and two-DOF models. In the printer structure experiment, the first mode of 308 Hz was successfully controlled with a one-DOF model.

• 한국산학기술학회:학술대회논문집
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• 한국산학기술학회 2008년도 춘계학술발표논문집
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• pp.173-176
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• 2008

The aim of this review is to acquaint a circuit designer with features of piezoelectric ceramic transformers(PT) and to show the general approach to the design of inverters utilizing PT as a circuit element. The description of the piezoelectric effect is not present here and can be easily found in numerous publications as well as complex equations and formulae. What is the most important to understand is that "they are different" - one cannot just change an electromagnetic transformer (EMT) for a piezoelectric one. Several examples of PT-based circuitry will help to start and use PT's advantages most effectively.

• Advances in robotics research
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• 제1권1호
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• pp.1-19
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• 2014

Microgripper is an essential device in the micro-operation system. It can convert other types of energy into mechanical energy and produce clamp movement with required chucking force, which enables it a broad application prospect in the domain of tiny components' processing and assembly, biomedicine and optics, etc. The performance of a microgripper is dependent on its power supply, type of drive, mechanism structure, sensing components, and controller. This paper presents a state-of-the-art survey of recent development on flexure-based microgrippers. According to the drive type, the existing microgrippers can be mainly classified as electrostatic microgripper, electrothermal microgripper, electromagnetic microgripper, piezoelectric microgripper, and shape memory alloy microgripper. Additionally, some different mechanisms, sensors, and control methods that are used in microgripper system are reviewed. The key issue of how to choose those components in microgripper system design is also addressed.

• Composites Research
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• 제23권2호
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• pp.24-30
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• 2010

니켈-나노분말/에폭시 복합재료의 계면 특성과 소수성을 자체-감지능과 작동기 측정을 위해 평가하였다. 경사형 시편을 사용하여 접촉 저항 및 저항도를 측정하였다. 자기장에서 복합재료의 작동성을 세가지 파형들, 즉, 싸인, 삼각, 그리고 사각파를 사용하여 평가하였다. 균일하지 않은 표면에 존재하는 소수성 영역 때문에 Ni-에폭시 나노복합재료의 어떤 부분은 초소수성보다는 다소 낮은 접촉각인 110도를 가졌다. 동적 접촉각은 정적 접촉각과 경향이 상호 일치함을 보였다. 니켈-나노분말의 고유의 금속성질 때문에 자체 감지를 확인하였으며, 또한 전자기장에 작동 반응을 잘 하였다. 니켈-나노분말/에폭시 복합재료의 최대 및 최적의 성능을 얻기 위해서, 레이져 변위 센서를 사용하여, 파형, 주파수, 그리고 전압의 함수로 작동기의 변위를 평가하였다. 니켈-나노분말/에폭시 복합재료의 작동은 적용된 주파수와 전압의 함수로써 증가하였다. 작동된 복합재료들의 연신율은 전압의 증가에 따라 삼각 혹은 사각파보다 싸인파에서 더욱 빨리 증가하였다.

• 한국산학기술학회논문지
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• 제15권4호
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• pp.2320-2323
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• 2014

본 논문에서는 냉음극 방전램프 구동용 압전 인버터를 설계하였다. 등가회로의 모델링 방법으로는 진동자의 모델에 많이 이용되고 있는 어드미턴스 궤적법을 사용하였고, 인버터 설계 시 전자회로 해석프로그램인 PSIM을 사용하여 압전 인버터 설계에 대한 검증을 하였다. 압전기 영향의 기술은 다수의 연구에서 복잡한 방정식과 공식도 쉽게 찾을 수 있다. 특히 압전기 세라믹 EMT가 변화하지 않으며 PT기초 전기소자의 여러 가지 예는 더욱 효과적인 PT의 강점을 이용하는데 도움이 될 것이다. 과적으로, 회로의 단순화와 그에 따른 소형화 그리고 입출력대비 효율이 최대 90%이상으로 우수한 성능을 보였다.

• 한국산학기술학회논문지
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• 제11권4호
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• pp.1229-1232
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• 2010

본 논문은 고효율 강압형 적층 압전변압기를 개발하기 위하여 저온소결 세라믹스 개발 및 적층 변압기를 제작하였다. 그리고 회로 요소로써 사용하는 PT는 인버터 설계의 일반적인 접근법을 보여주기 위한 것이다. 또한 압전기 영향의 기술(記述)은 다수의 연구에서 복잡한 방정식과 공식도 쉽게 찾을 수 있다. 특히 압전기 세라믹 EMT가 변화하지 않으며 PT기초 전기소자의 여러 가지 예는 더욱 효과적인 적층변압기의 적용이 가능할 것으로 판단된다.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2005년도 제36회 하계학술대회 논문집 D
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• pp.2809-2811
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• 2005

In this paper, we address an active vibration control system, which suppresses the vibration engaged by magnetically levitated stage. The stage system consists of a levitating platen with four permanent magnetic linear synchronous motors in parallel. Each motor generates vertical force for suspension against gravity and propulsion force horizontally as well. This stage can generate six degrees of freedom motion via the vertical and horizontal forces. In the stage system, which represents the settling-time critical system, the motion of the platen vibrates mechanically. We designed an active vibration control system for suppressing vibration due to the stage moving. The command feedforward with inertial feedback algorithm is used for solving stage system's critical problems. The components of the active vibration control system are accelerometers for detecting stage tables's vibrations, a digital controller with high precise signal converters, and electromagnetic actuators.