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RISS 인기검색어
- 검색키워드
- 저자 : Willey Y. H. Liew (검색결과 2 건)
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Increasing the Output from Piezoelectric Energy Harvester Using Width-Split Method with Verification
Chow Man Sang,Jedol Dayou,Willey Y. H. Liew 한국정밀공학회 2013 International Journal of Precision Engineering and Vol. No.
This paper proposes a new scheme for piezoelectric energy harvesting maximization. The proposed enhancement relies on a new topology of splitting a specified dimension piezo composite bender into beams with smaller width and, therefore, higher quality factor (or Q factor). The increase of Q factor allows a much more effective energy conversion process. It is shown that the proposed method,based on single splitting, increases the harvested power by a factor of up to √6, and up to √7.62 for two even-splitting compared to with no splitting. The wideband operation is accomplished by using different resonating benders in such a way that individual benders are each tuned to a different resonance frequency. Taking the configuration of single even-splitting as an example, the power output of the prototype was 39 μW at 27.2 Hz with 8 Hz bandwidth under 2 mm peak-to-peak input displacement and 3 Hz variation in resonant frequency. This corresponds to more than 2 times of power output with no splitting as well as about 23% increase in bandwidth. Such power output is sufficient to power up electronics devices such as a “2 AA dry cells-powered” digital clock with the wider range operating frequency.
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DLC 코팅된 60E1(UIC60) 강의 건조 마찰에서의 미끄럼 마찰 거동
김종형(Jong-Hyoung Kim),정재일(Jae-Il Jeong),김재원(Jae-Won Kim),김태규(Tae-Gyu Kim),Chau Kian Hao,Willey Y. H. Liew,김석삼(Seock-Sam Kim) 대한기계학회 2020 大韓機械學會論文集A Vol.44 No.2
본 논문은 철도 레일용으로 사용되는 60E1 강 표면에 RF-PECVD 방법으로 Si-doped DLC 코팅과 non-doped DLC 코팅을 제작하여 ball-on-disk형 마찰시험기로 실험을 수행하고 DLC 코팅층의 경도와 마찰 특성을 평가하였다. 시험 결과, Si-doped DLC 코팅층의 경도가 non-doped DLC 코팅층보다 높게 나타났으며 마찰 계수는 낮게 나타났다. SEM 사진의 미시적 마찰면의 관찰 결과, non-doped DLC면에는 표면균열과 응착에 의한 마찰면이 관찰되었고, Si-doped DLC의 마찰면은 응착 유동에 의한 응착과 이착이 주된 마찰 메카니즘이었다. In this study, the nano-hardness and frictional behavior of non-doped DLC (diamond-like carbon) and Sidoped DLC coated 60E1 steel deposited by RF-PECVD method were investigated. The results showed that Si-doped DLC exhibited higher nano-hardness and lower friction coefficient than the non-doped DLC from ball-on-disk type tribometer. By using SEM (scanning electron microscope), SEM images showed friction mechanism of the base material was adhesion and that of DLC showed adhesion and brittle fracture. owever, Si-doped DLC showed adhesion friction and transfer layer of DLC to counterpart.
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