http://chineseinput.net/에서 pinyin(병음)방식으로 중국어를 변환할 수 있습니다.
변환된 중국어를 복사하여 사용하시면 됩니다.
Kim, Changho,Ko, Youngsu,Kim, Taemin,Yoo, Chan-Sei,Choi, BeomJin,Han, Seung Ho,Jang, YongHo,Kim, Youngho,Kim, Namsu Techno-Press 2018 Smart Structures and Systems, An International Jou Vol.22 No.2
Increasing interest in prognostics and health management has heightened the need for wireless sensor networks (WSN) with efficient power sources. Piezoelectric energy harvesters using Pb(Zr,Ti)O3 (PZT) are one of the candidate power sources for WSNs as they efficiently convert mechanical vibration energy into electrical energy. These types of devices are resonated at a specific frequency, which has a significant impact on the amount of energy harvested, by external vibration. Hence, precise prediction of mechanical deformation including modal analysis of piezoelectric devices is crucial for estimating the energy generated under specific conditions. In this study, an experimental vibrational system capable of controlling a wide range of frequencies and accelerations was designed to generate mechanical vibration for piezoelectric energy harvesters. In conjunction with MATLAB, the system automatically finds the resonance frequency of harvesters. A small accelerometer and non-contact laser displacement sensor are employed to investigate the mechanical deformation of harvesters. Mechanical deformation under various frequencies and accelerations were investigated and analyzed based on data from two types of sensors. The results verify that the proposed system can be employed to carry out vibration experiments for piezoelectric harvesters and measurement of their mechanical deformation.
Hollow Microtube Resonators via Silicon Self-Assembly toward Subattogram Mass Sensing Applications
Kim, Joohyun,Song, Jungki,Kim, Kwangseok,Kim, Seokbeom,Song, Jihwan,Kim, Namsu,Khan, M. Faheem,Zhang, Linan,Sader, John E.,Park, Keunhan,Kim, Dongchoul,Thundat, Thomas,Lee, Jungchul American Chemical Society 2016 Nano letters Vol.16 No.3
<P>Fluidic resonators with integrated microchannels (hollow resonators) are attractive for mass, density, and volume measurements of single micro/nanoparticles and cells, yet their widespread use is limited by the complexity of their fabrication. Here we report a simple and cost-effective approach for fabricating hollow microtube resonators. A prestructured silicon wafer is annealed at high temperature under a controlled atmosphere to form self-assembled buried cavities. The interiors of these cavities are oxidized to produce thin oxide tubes, following which the surrounding silicon material is selectively etched away to suspend the oxide tubes. This simple three-step process easily produces hollow microtube resonators. We report another innovation in the capping glass wafer where we integrate fluidic access channels and getter materials along with residual gas suction channels. Combined together, only five photolithographic steps and one bonding step are required to fabricate vacuum-packaged hollow microtube resonators that exhibit quality factors as high as similar to 13 000. We take one step further to explore additionally attractive features including the ability to tune the device responsivity, changing the resonator material, and scaling down the, resonator size. The resonator wall thickness of similar to 120 nm and the channel hydraulic diameter of similar to 60 nm are demonstrated solely by conventional microfabrication approaches. The unique characteristics of this new fabrication process facilitate the widespread use of hollow microtube resonators, their translation between diverse research fields, and the production of commercially viable devices.</P>
Changho Kim,Youngsu Ko,Taemin Kim,유찬세,BeomJin Choi,한승호,YongHo Jang,Youngho Kim,Namsu Kim 국제구조공학회 2018 Smart Structures and Systems, An International Jou Vol.22 No.2
Increasing interest in prognostics and health management has heightened the need for wireless sensor networks (WSN) with efficient power sources. Piezoelectric energy harvesters using Pb(Zr,Ti)O3 (PZT) are one of the candidate power sources for WSNs as they efficiently convert mechanical vibration energy into electrical energy. These types of devices are resonated at a specific frequency, which has a significant impact on the amount of energy harvested, by external vibration. Hence, precise prediction of mechanical deformation including modal analysis of piezoelectric devices is crucial for estimating the energy generated under specific conditions. In this study, an experimental vibrational system capable of controlling a wide range of frequencies and accelerations was designed to generate mechanical vibration for piezoelectric energy harvesters. In conjunction with MATLAB, the system automatically finds the resonance frequency of harvesters. A small accelerometer and non-contact laser displacement sensor are employed to investigate the mechanical deformation of harvesters. Mechanical deformation under various frequencies and accelerations were investigated and analyzed based on data from two types of sensors. The results verify that the proposed system can be employed to carry out vibration experiments for piezoelectric harvesters and measurement of their mechanical deformation.
Kim, Sung Hyun,Kim, Dongwhan,Kim, Namsu IEEE 2017 IEEE journal of photovoltaics Vol.7 No.2
<P>In this paper, the correlation between the shelf life of the encapsulated organic photovoltaic (PV) module and different damp heat conditions was investigated by calculating the total amount of water vapor permeated into the organic PV modules. The organic PV module was encapsulated with a commercially available barrier-coated polyethylene terephthalate (PET) substrate by using an optically clear adhesive. The total amount of the permeated water vapor into the module during the damp heat test was calculated by using the finite-element method. Based on simulation results from accelerated damp heat conditions, the lifetime of the module operated at 25 degrees C/50% relative humidity was predicted. Additionally, it was found that the dominant permeation path of the water vapor into the module is the side edge area and not the barrier-coated PET, based on results from experiment and simulation. Hence, the extension of lifetime for the encapsulated organic PV module was demonstrated by side sealing.</P>