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알루미늄 핀-조인트를 사용한 마이크로 미러의 제작과 측정
지창현,김용권,Ji, Chang-Hyeon,Kim, Yong-Gwon 대한전기학회 2000 전기학회논문지C Vol.54 No.12
This paper describes the design, fabrication and experiments of surface-micromachined aluminum micromirror array with hidden pin-joints. Instead of the conventional elastic spring components as connection between mirror plate and supporting structure, we used pin-joint composed of pin and staples to support the mirror plate. The placement of pin-joint under the mirror plate makes large active surface area possible. These flexureless micromirrors are driven by electrostatic force. As the mirror plate has discrete deflection angles, the device can be ap;lied to adaptive optics and digitally-operating optical applications. Four-level metal structural layers and semi-cured photoresist sacrificial layers were used in the fabrication process and sacrificial layers were removed by oxygen plasma ashing. Static characteristics of fabricated samples were measured and compared with modeling results.
100X110μm² micro mirror array의 제작과 실험
지창현,정석환,신종우,김용권,최범규,안세진 경북대학교 센서기술연구소 1995 센서技術學術大會論文集 Vol.6 No.1
A 100 x110μm^(2) aluminum micro structure is fabricated using thick photoresist as sacrificial layer and mold for nickel electroplating. The micro structure is composed of aluminum plate, hinge, nickel support post, and address electrode. The aluminum plate is overhung about 10 μm above the silicon substrate supported by two nickel posts. The hinge connects the aluminum plate and the support post and works as a torsional spring. We used thick PR as 10 μm thick sacrificial layer and nickel electroplating mold and electroplated nickel for 10 μm high post. The aluminum plate is actuated by electrostatic force between the aluminum plate and the address electrode. The aluminum micro structure is finally released by reactive ion etching (RIE) using O_(2). The micro mirror is actuated at 35V.
이중 질량체를 사용한 진동형 자이로스코프의 검출부 대역폭 개선
황영석(Yong Suk Hwang),김용권(Yong-Kweon Kim),지창현(Chang-Hyeon Ji) 대한전기학회 2011 전기학회논문지 Vol.60 No.9
In this research, a MEMS vibratory gyroscope with dual-mass system in the sensing mode has been proposed to increase the stability of the device using wide bandwidth. A wide flat region between the two resonance peaks of the dual-mass system removes the need for a frequency matching typically required for single mass vibratory gyroscopes. Bandwidth, mass ratio, spring constant, and frequency response of the dual-mass system have been analyzed with MATLAB and ANSYS simulation. Designed first and second peaks of sensing mode are 5,917 and 8,210㎐, respectively. Driving mode resonance frequency of 7,180㎐ was located in the flat region between the two resonance peaks of the sensing mode. The device is fabricated with anodically bonded silicon-on-glass substrate. The chip size is 6㎜ⅹ6㎜ and the thickness of the silicon device layer is 50㎛. Despite the driving mode resonance frequency decrease of 2.8㎑ and frequency shift of 176㎐ from the sensing mode due to fabrication imperfections, measured driving frequency was located within the bandwidth of sensing part, which validates the utilized dual-mass concept. Measured bandwidth was 768㎐. Sensitivity calculated with measured displacement of driving and sensing parts was 22.4aF/deg/sec. Measured slope of the sensing point was 0.008㏈/㎐.
주선아(Suna Ju),지창현(Chang-Hyeon Ji) 대한전기학회 2017 전기학회논문지 Vol.66 No.10
This paper presents an impact-based piezoelectric vibration energy harvester using a freely movable metal sphere and a piezoceramic fiber-based MFC (Macro Fiber Composite) as piezoelectric cantilever. The free motion of the metal sphere, which impacts both ends of the cavity in an aluminum housing, generates power across a cantilever-type MFC beam in response to low frequency vibration such as human-body-induced motion. Impacting force of the spherical proof mass is transformed into the vibration of the piezoelectric cantilever indirectly via the aluminum housing. A proof-of-concept energy harvesting device has been fabricated and tested. Effect of the indirect impact-based system has been tested and compared with the direct impact-based counterpart. Maximum peak-to-peak open circuit voltage of 39.8V and average power of 598.9μW have been obtained at 3g acceleration at 18Hz. Long-term reliability of the fabricated device has been verified by cyclic testing. For the improvement of output performance and reliability, various devices have been tested and compared. Using device fabricated with anodized aluminum housing, maximum peak-to-peak open-circuit voltage of 34.4V and average power of 372.8μW have been obtained at 3g excitation at 20Hz. In terms of reliability, housing with 0.5mm-thick steel plate and anodized aluminum gave improved results with reduced power reduction during initial phase of the cyclic testing.
Realistic Circuit Model of an Impact-Based Piezoelectric Energy Harvester
김선희,주선아,지창현,이승준 대한전자공학회 2015 Journal of semiconductor technology and science Vol.15 No.5
A vibration-based energy harvester and its equivalent circuit models have been reported. Most models predict voltage signals at harmonic excitation. However, vibrations in a natural environment are unpredictable in frequency and amplitude. In this paper, we propose a realistic equivalent circuit model of a frequency-up-converting impact-based piezoelectric energy harvester. It can describe the behavior of the harvester in a real environment where the frequency and the amplitude of the excitation vary arbitrarily. The simulation results of the model were compared with experimental data and showed good agreement. The proposed model can predict both the impact response and long term response in a non-harmonic excitation. The model is also very useful to analyze the performance of energy conversion circuitry with the harvester.