• Title/Summary/Keyword: MEMS

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An Effectiveness Analysis of Commercial Vehicle's Loading Pattern and Prevention of Overloading with On-board Truck Weight Sensors (화물차량 부착 중량센서 적용을 통한 운행패턴 및 과적 예방 효과 분석)

  • Kim, Jong Woo;Jho, Youn Beom;Jung, Young Woo
    • The Journal of The Korea Institute of Intelligent Transport Systems
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    • v.17 no.6
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    • pp.153-172
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    • 2018
  • Overloading of Commercial vehicles have been an important area of transportation as one of the main causes of pavement damage, bridge collapse, severe traffic accident, etc. In this study, we analyzed the effects of overweight prevention by analyzing overweight driving patterns and using weight sensors. First, we analyzed relevant literatures of overweight and surveyed the commercial weight sensors. Then we chose the typical type of overweight vehicles based of overweight enforcement data analysis. MEMs inclinometer weight sensor were installed to 10 test vehicles and data was collected by weight sensors and gps in real time. As a result of gross vehicle weight and axle weight analysis, it was found weight sensor could decrease overweight rate. However, since the number of samples of test vehicles is insufficient to represent the whole commercial vehicle, further studies are deemed possible through the extension test.

Evaluations on Performances of a Non-Contact Torque Measurement Technique for Rotatory Machinery (회전기계용 비접촉식 토크 측정법 성능 평가)

  • KIM, YEONGHWAN;KIM, YEONGHO;CHO, GYEONGRAE;KIM, UEIKAN;DOH, DEOGHEE
    • Transactions of the Korean hydrogen and new energy society
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    • v.29 no.6
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    • pp.642-647
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    • 2018
  • Gas compressors are mostly driven by motors. It is important to measure the power of motors to evaluate their power efficiency, because the mechanical loads of gas compressors are always varied. In order to measure the power given to the driving motors, the torque should be measured. Manufacturers of compressors usually use the torque data to calculate the compressors qualities such as power consumption, efficiencies and failures. In general, measurements for the shaft torque of the compressors have been based upon contact types, strain gauges. In the cases of larger compressors, the contact type of strain gauges have several disadvantages such as large size and high cost. In this study, a relatively inexpensive and simple torque sensing technique that is not restricted to shaft diameter is introduced using visualization technique. Particle image velocimetry (PIV) has been adopted to complete non-contact torques measurements for rotating motors. In order to compare the performance of the newly constructed torque measurement technique, torque measurement by a transducer based on MEMS technology has been performed simultaneously during experiments.

Buckling treatment of piezoelectric functionally graded graphene platelets micro plates

  • Abbaspour, Fatemeh;Arvin, Hadi
    • Steel and Composite Structures
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    • v.38 no.3
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    • pp.337-353
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    • 2021
  • Micro-electro-mechanical systems (MEMS) are widely employed in sensors, biomedical devices, optic sectors, and micro-accelerometers. New reinforcement materials such as carbon nanotubes as well as graphene platelets provide stiffer structures with controllable mechanical specifications by changing the graphene platelet features. This paper deals with buckling analyses of functionally graded graphene platelets micro plates with two piezoelectric layers subjected to external applied voltage. Governing equations are based on Kirchhoff plate theory assumptions beside the modified couple stress theory to incorporate the micro scale influences. A uniform temperature change and external electric field are regarded along the micro plate thickness. Moreover, an external in-plane mechanical load is uniformly distributed along the micro plate edges. The Hamilton's principle is employed to extract the governing equations. The material properties of each composite layer reinforced with graphene platelets of the considered micro plate are evaluated by the Halpin-Tsai micromechanical model. The governing equations are solved by the Navier's approach for the case of simply-supported boundary condition. The effects of the external applied voltage, the material length scale parameter, the thickness of the piezoelectric layers, the side, the length and the weight fraction of the graphene platelets as well as the graphene platelets distribution pattern on the critical buckling temperature change and on the critical buckling in-plane load are investigated. The outcomes illustrate the reduction of the thermal buckling strength independent of the graphene platelets distribution pattern while meanwhile the mechanical buckling strength is promoted. Furthermore, a negative voltage, -50 Volt, strengthens the micro plate stability against the thermal buckling occurrence about 9% while a positive voltage, 50 Volt, decreases the critical buckling load about 9% independent of the graphene platelet distribution pattern.

A review of 3D printing technology for piezoresistive strain/loadcell sensors (3D 프린팅 센서 연구 동향 소개-전왜성 변형/로드셀 센서 중심으로)

  • Cho, Jeong Hun;Moon, Raymond Hyun Woo;Kim, Sung Yong;Choi, Baek Gyu;Oh, Gwang Won;Joung, Kwan Young;Kang, In Pil
    • Journal of Sensor Science and Technology
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    • v.30 no.6
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    • pp.388-394
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    • 2021
  • The conventional microelectromechanical system (MEMS) process has been used to fabricate sensors with high costs and high-volume productions. Emerging 3D printing can utilize various materials and quickly fabricate a product using low-cost equipment rather than traditional manufacturing processes. 3D printing also can produce the sensor using various materials and design its sensing structure with freely optimized shapes. Hence, 3D printing is expected to be a new technology that can produce sensors on-site and respond to on-demand demand by combining it with open platform technology. Therefore, this paper reviews three standard 3D printing technologies, such as Fused Deposition Modeling (FDM), Direct Ink Writing (DIW), and Digital Light Processing (DLP), which can apply to the sensor fabrication process. The review focuses on strain/load sensors having both sensing material features and structural features as well. NCPC (Nano Carbon Piezoresistive Composite) is also introduced as a promising 3D material due to its favorable sensing characteristics.

Optimization of SnO2 Based H2 Gas Sensor Along with Thermal Treatment Effect (열처리 효과에 따른 SnO2 기반 수소가스 센서의 특성 최적화)

  • Jung, Dong Geon;Lee, Junyeop;Kwon, Jinbeom;Maeng, Bohee;Kim, Young Sam;Yang, Yi Jun;Jung, Daewoong
    • Journal of Sensor Science and Technology
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    • v.31 no.5
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    • pp.348-352
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    • 2022
  • Hydrogen gas (H2) which is odorless, colorless is attracting attention as a renewable energy source in varions applications but its leakage can lead to disastrous disasters, such as inflammable, explosive, and narcotic disasters at high concentrations. Therefore, it is necessary to develop H2 gas sensor with high performance. In this paper, we confirmed that H2 gas detection ability of SnO2 based H2 gas sensor along with thermal treatment effect of SnO2. Proposed SnO2 based H2 gas sensor is fabricated by MEMS technologies such as photolithgraphy, sputtering and lift-off process, etc. Deposited SnO2 thin films are thermally treated in various thermal treatement temperature in range of 500-900 ℃ and their H2 gas detection ability is estimatied by measuring output current of H2 gas sensor. Based on experimental results, fabricated H2 gas sensor with SnO2 thin film which is thermally treated at 700 ℃ has a superior H2 gas detection ability, and it can be expected to utilize at the practical applications.

Bending of axially functionally graded carbon nanotubes reinforced composite nanobeams

  • Ahmed Drai;Ahmed Amine Daikh;Mohamed Oujedi Belarbi;Mohammed Sid Ahmed Houari;Benoumer Aour;Amin Hamdi;Mohamed A. Eltaher
    • Advances in nano research
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    • v.14 no.3
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    • pp.211-224
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    • 2023
  • This work presents a modified analytical model for the bending behavior of axially functionally graded (AFG) carbon nanotubes reinforced composite (CNTRC) nanobeams. New higher order shear deformation beam theory is exploited to satisfy parabolic variation of shear through thickness direction and zero shears at the bottom and top surfaces.A Modified continuum nonlocal strain gradient theoryis employed to include the microstructure and the geometrical nano-size length scales. The extended rule of the mixture and the molecular dynamics simulations are exploited to evaluate the equivalent mechanical properties of FG-CNTRC beams. Carbon nanotubes reinforcements are distributed axially through the beam length direction with a new power graded function with two parameters. The equilibrium equations are derived with associated nonclassical boundary conditions, and Navier's procedure are used to solve the obtained differential equation and get the response of nanobeam under uniform, linear, or sinusoidal mechanical loadings. Numerical results are carried out to investigate the impact of inhomogeneity parameters, geometrical parameters, loadings type, nonlocal and length scale parameters on deflections and stresses of the AFG CNTRC nanobeams. The proposed model can be used in the design and analysis of MEMS and NEMS systems fabricated from carbon nanotubes reinforced composite nanobeam.

Design and Simulation Study on Three-terminal Graphene-based NEMS Switching Device (그래핀 기반 3단자 NEMS 스위칭 소자 설계 및 동작 시뮬레이션 연구)

  • Kwon, Oh-Kuen;Kang, Jeong Won;Lee, Gyoo-Yeong
    • Asia-pacific Journal of Multimedia Services Convergent with Art, Humanities, and Sociology
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    • v.8 no.6
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    • pp.939-946
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    • 2018
  • In this work, we present simple schematics for a three-terminal graphene-based nanoelectromechanical switch with the vertical electrode, and we investigated their operational dynamics via classical molecular dynamics simulations. The main structure is both the vertical pin electrode grown in the center of the square hole and the graphene covering on the hole. The potential difference between the bottom gate of the hole and the graphene of the top cover is applied to deflect the graphene. By performing classical molecular dynamic simulations, we investigate the nanoelectromechanical properties of a three-terminal graphene-based nanoelectromechanical switch with vertical pin electrode, which can be switched by the externally applied force. The elastostatic energy of the deflected graphene is also very important factor to analyze the three-terminal graphene-based nanoelectromechanical switch. This simulation work explicitly demonstrated that such devices are applicable to nanoscale sensors and quantum computing, as well as ultra-fast-response switching devices.

Performance Evaluation of Smart Accelerometers for Structural Health Monitoring (구조 건전성 감시를 위한 스마트 가속도계의 성능 평가)

  • Yi, Jin-Hak;O, Hye-Sun;Yun, Chung-Bang
    • KSCE Journal of Civil and Environmental Engineering Research
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    • v.26 no.4A
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    • pp.605-609
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    • 2006
  • In this study, two kinds of smart accelerometers are investigated for the application of smart sensors to the structural health monitoring of infrastructures. Smart optical Fiber Bragg Grating (FBG) type and Micro-Electo-Mechanical System (MEMS) type accelerometers are selected for this study and the high sensitive ICP type accelerometer is used for the reference sensor. Small size shaking table tests were performed with 3-story shear building model using random input ground motions. The output only modal identification was carried out using stochastic subspace identification and the performances of sensors are compared in modal domain indirectly. The modal sensitivity method was applied to update the story stiffness of numerical model and the updated results were verified using the additional experiments for the same structure with additional mass.

Influence of flexoelectricity on bending of piezoelectric perforated FG composite nanobeam rested on elastic foundation

  • Ali Alnujaie;Alaa A. Abdelrahman;Abdulrahman M. Alanasari;Mohamed A. Eltaher
    • Steel and Composite Structures
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    • v.49 no.4
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    • pp.361-380
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    • 2023
  • A size dependent bending behavior of piezoelectrical flexoelectric layered perforated functionally graded (FG) composite nanobeam rested on an elastic foundation is investigated analytically. The composite beam is composed of regularly cutout FG core and two piezoelectric face sheets. The material characteristics is graded through the core thickness by power law function. Regular squared cutout perforation pattern is considered and closed forms of the equivalent stiffness parameters are derived. The modified nonlocal strain gradient elasticity theory is employed to incorporate the microstructure as well as nonlocality effects into governing equations. The Winkler as well as the Pasternak elastic foundation models are employed to simulate the substrate medium. The Hamiltonian approach is adopted to derive the governing equilibrium equation including piezoelectric and flexoelectric effects. Analytical solution methodology is developed to derive closed forms for the size dependent electromechanical as well as mechanical bending profiles. The model is verified by comparing the obtained results with the available corresponding results in the literature. To demonstrate the applicability of the developed procedure, parametric studies are performed to explore influences of gradation index, elastic medium parameters, flexoelectric and piezoelectric parameters, geometrical and peroration parameters, and material parameters on the size dependent bending behavior of piezoelectrically layered PFG nanobeams. Results obtained revealed the significant effects both the flexoelectric and piezoelectric parameters on the bending behavior of the piezoelectric composite nanobeams. These parameters could be controlled to improve the size dependent electromechanical as well as mechanical behaviors. The obtained results and the developed procedure are helpful for design and manufacturing of MEMS and NEMS.

Dry Etching of Flexible Polycarbonate and PMMA in O2/SF6/CH4 Discharges (O2/SF6/CH4 플라즈마를 이용한 플렉시블 Polycarbonate와 PMMA의 건식 식각)

  • Joo, Y.W.;Park, Y.H.;Noh, H.S.;Kim, J.K.;Lee, J.W.
    • Journal of the Korean Vacuum Society
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    • v.18 no.2
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    • pp.85-91
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    • 2009
  • There has been a rapid progress for flexible polymer-based MEMS(Microelectromechanical Systems) technology. Polycarbonate (PC) and Poly Methyl Methacrylate (PMMA), so-called acrylic, have many advantages for optical, non-toxic and micro-device application. We studied dry etching of PC and PMMA as a function of % gas ratio in the $O_2/SF_6/CH_4$ temary plasma. A photoresist pattern was defined on the polymer samples with a mask using a conventional lithography. Plasma etching was done at 100 W RIE chuck power and 10 sccm total gas flow rate. The etch rates of PMMA were typically 2 times higher than those of PC in the whole experimental range. The result would be related to higher melting point of PC compared to that of PMMA. The highest etch rates of PMMA and PC were found in the $O_2/SF_6$ discharges among $O_2/SF_6$, $O_2/CH_4$ and $SF_6/CH_4$ and $O_2/SF_6/CH_4$ plasma composition (PC: ${\sim}350\;nm/min$ at 5 sccm $O_2/5$ sccm $SF_6$, PMMA: ${\sim}570\;nm/min$ at 2.5 sccm $O_2/7.5$ sccm $SF_6$). PC has smoother surface morphology than PMMA after etching in the $O_2/SF_6/CH_4$ discharges. The surface roughness of PC was in the range of 1.9$\sim$3.88 nm. However, that of PMMA was 17.3$\sim$26.1 nm.