• Smart Structures and Systems
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• 제7권5호
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• pp.365-378
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• 2011

Piezo-based active structural health monitoring (SHM) requires amplifiers specifically designed for capacitive loads. Moreover, with the increase in number of applications of wireless SHM systems, energy efficiency and cost reduction for this type of amplifiers is becoming a requirement. General lab grade amplifiers are big and costly, and not built for outdoor environments. Although some piezoceramic power amplifiers are available in the market, none of them are specifically targeting the wireless constraints and low power requirements. In this paper, a piezoceramic transducer amplifier for wireless active SHM systems has been designed. Power requirements are met by two digital On/Off switches that set the amplifier in a standby state when not in use. It provides a stable ${\pm}180$ Volts output with a bandwidth of 7k Hz using a single 12 V battery. Additionally, both voltage and current outputs are provided for feedback control, impedance check, or actuator damage verification. Vibration control tests of an aluminum beam were conducted in the University of Houston lab, while wireless active SHM tests of a wind turbine blade were performed in the Harbin Institute of Technology wind tunnel. The results showed that the developed amplifier provided equivalent results to commercial solutions in suppressing structural vibrations, and that it allows researchers to perform active wireless SHM on moving objects with no power wires from the grid.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2006년도 춘계학술대회 논문집
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• pp.289-290
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• 2006

In general, atomic force microscope (AFM) used for metrological purpose has measuring range less than a few hundred micrometers. We design and fabricate an AFM with long measuring range of $200mm{\times}200mm$ in X and Y axes. The whole stage system is composed of surface plate, global stage, microstage. By combining global stage and microstage, the fine and long movement can be provided. We measure the position of the stage and angular motions of the stage by laser interferometer. A piezoresistive type cantilever is used for compact and long term stability and a flexure structure with PZT and capacitive sensor is used for Z axis feedback control. Since the system is composed of various actuators and sensors, a real time control program is required for the implementation of AFM. Therefore, in this work, we designed a multi-axis control program using a FPGA module, which has various functions such as interferometer signal converting, PID control and data acquisition with triggering. The control program achieves a loop rate more than 500 kHz and will be applied for the measurement of grating pitch and step height.

• 반도체디스플레이기술학회지
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• 제20권4호
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• pp.171-176
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• 2021

Die-to-wafer (D2W) hybrid bonding in the multilayer semiconductor manufacturing process is one of wafer direct bonding, and various studies are being conducted around the world. A noteworthy point in the current die-to-wafer process is that a lot of voids occur on the bonding surface of the die during bonding. In this study, as a suggested method for removing voids generated during the D2W hybrid bonding process, a flexible mechanism for implementing convex for die bonding to be applied to the bond head is proposed. In addition, modeling of flexible mechanisms, analysis/design/control/evaluation of static/dynamics properties are performed. The proposed system was controlled by capacitive sensor (lion precision, CPL 290), piezo actuator (P-888,91), and dSpace. This flexure mechanism implemented a working range of 200 ㎛, resolution(3σ) of 7.276nm, Inposition(3σ) of 3.503nm, settling time(2%) of 500.133ms by applying a reverse bridge type mechanism and leaf spring guide, and at the same time realized a maximum step difference of 6 ㎛ between die edge and center. The results of this study are applied to the D2W hybrid bonding process and are expected to bring about an effect of increasing semiconductor yield through void removal. In addition, it is expected that it can be utilized as a system that meets the convex variable amount required for each device by adjusting the elongation amount of the piezo actuator coupled to the flexible mechanism in a precise unit.

• 전기화학회지
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• 제2권1호
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• pp.17-22
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• 1999

다공질 실리콘을 이용한 마이크로센서와 마이크로액츄에이터의 연구는 현재 초기단계에 있기 때문에, 지금까지 발광 다이오드나 화학 센서 등과 같은 몇몇 응용 소자가 발표된 수준에 머물러 있다. 본 논문에서는 화학 센서와 광소자를 중심으로 다공질 실리콘 센서 및 액추에이터 연구현황을 고찰 보고하고자 한다. 정전용량형 다공질 실리콘 습도센서의 감습 특성은 비선형이였으며, 저습보다는 $40\%RH$ 이상의 고습영역에서 더 높은 감도를 나타내었다. 다공질 실리콘 $n^+-p-n^+$ 소자는 에탄올에 노출되었을 때 소자 전류가 급격히 증가하였다. 다공질 실리콘 다이어프램에 제작된 $p^+-PSi-n^+$ 다이오드는 광 스위칭 현상을 나타내어 광센서 또는 광스위치로써의 응용 가능성을 보여주었다. 다공질 실리콘에 365nm를 조사해서 얻어진 광루미네센스(PL)는 넓은 스펙트럼을 보였으며, 피크 파장은 610 nm이었다. ITO/PSi/In LED의 전계발광(EL)스펙트럼은 PL에 비해 약간 더 넓은 영역에 걸쳐 나타났으며, 피크 에너지가 단파장(535nm)으로 이동하였다.