• 제목/요약/키워드: electro-mechanical systems

검색결과 416건 처리시간 0.029초

초음속 마이크로제트 유동의 수치해석적 가시화 (Numerical Visualization of Supersonic Microjet Flows)

  • 신춘식;이종성;김희동
    • 한국가시화정보학회지
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    • 제7권2호
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    • pp.35-41
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    • 2010
  • Supersonic microjets acquire considerable research interest from a fundamental fluid dynamics perspective, in part because the combination of highly compressible flow at low-to-moderate Reynolds number is not very common, and in part due to the complex nature of the flow itself. In addition, microjets have a great variety engineering applications such as micro-propulsion, MEMS(Micro-Electro Mechanical Systems) components, microjet actuators and fine particle deposition and removal. Numerical simulations have been carried out at moderate nozzle pressure ratios and for different nozzle exit diameters to investigate and to understand in-depth of aerodynamic characteristics of supersonic microjets.

TPMS 적용을 위한 가변 정전 용량형 압력센서 개발 (The development of a variable capacitive pressure sensor for TPMS(tire pressure monitoring system))

  • 최범규;김도형;오재근
    • 센서학회지
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    • 제14권4호
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    • pp.265-271
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    • 2005
  • In this study, a variable capacitive pressure sensor is fabricated for TPMS (Tire Pressure Monitoring System). This study is for developing sensors which consecutively measure the tire pressure given as 30 psi from the industrial standard. For improving non-linearity of the prior capacitive pressure sensors, it is suggested that touch mode capacitive pressure sensor be applied. In addition, initial capacitance is designed as small as possible for the conformity to the wireless sensor. ANSYS, commercial FEA package, is used for designing and simulating the sensor. The device is progressed by MEMS (Micro Electro Mechanical Systems) fabrication and packaged with PDMS. The result is obtained sensitivity, 1 pF/psi, through a pressure test. The simulation result is discrepant from experiment one. Wafer's uniformity is presumed as the main reason of discrepancy.

MEMS 소재의 기계적 특성 평가를 위한 인장형 시편 및 시험기 제작 (A Novel Tensile Specimen and Test Machine for Mechanical Properties of MEMS Materials)

  • 박준협;김정엽;이창승;좌성훈;송지호
    • 대한기계학회:학술대회논문집
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    • 대한기계학회 2004년도 춘계학술대회
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    • pp.258-263
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    • 2004
  • Mechanical property evaluation of micrometer-sized structures is necessary to help design reliable microelectromechanical systems(MEMS) devices. Most material properties are known to exhibit dependence on specimen size and such properties of microscale structures are not well characterized. This paper describes techniques developed for tensile testing of materials used in MEMS. Epi-polycrystalline silicon is currently the most widely used material, and its tensile strength has been measured as 1.52GPa. We have developed an uniaxial testing machine for testing microscale specimen using electro-magnetic actuator. The field magnet and the moving coil taken from an audio-speaker were utilized as the components of the actuator. Structure of specimen was designed and manufactured for easy handling and alignment. In addition to the static tensile tests, new techniques and procedures for measuring strength are described.

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마이크로 밀링 EDM 머신 개발 및 가공특성 분석 (Development of Micro Milling EDM and Analysis of Machined Characteristics)

  • 김선호;임한석
    • 한국기계가공학회지
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    • 제10권1호
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    • pp.1-7
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    • 2011
  • Micromachining is gaining popularity due to recent advancements in MEMS(Micro Electro Mechanical Systems). Using conventional micromachining, it is relatively difficult to produce moving components in the order of microns. Photolithography for silicon material has high accuracy machining, but it has low aspect ratio. X-ray lithography has ultra high accuracy machining, but it has expensive cost. Micro-EDM(electro discharge machining) has been gaining popularity as a new alternative method to fabricate micro-structures. In this study, Micro-EDM machine is developed available for fabricate micro-structures and two processes such as side cut EDM and milling EDM is proposed. Several sets of experiment results have been performed to study the characteristics of the machining process.

Development of a User-Friendly Automatic Control System for Electro-Slag Remelting Process

  • Lim, Tae-Gyoon;Reeu, Chang-Woo;Boo, Kwang-Suk
    • 제어로봇시스템학회:학술대회논문집
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    • 제어로봇시스템학회 2001년도 ICCAS
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    • pp.97.5-97
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    • 2001
  • This paper presents development of a user-friendly automatic control system for ESR(Electro-Slag Remelting or Refining) process. It is a second-phase refining one, commonly applied to production of high-purity specialty steel. A primarily refined castingot acts as a consumable electrode and melts by the electric resistance heat generated when high current is induced through a slag bath. The quality of product is evaluated by its chemical composition, purity, micro-structure, uniformity, mechanical property, etc. To meet the standards, above all things, the process should be kept sound and the melt rate should track the optimum profile irrespective of environment variations. Current ESR system is manually operated ...

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Linear elastic mechanical system interacting with coupled thermo-electro-magnetic fields

  • Moreno-Navarro, Pablo;Ibrahimbegovic, Adnan;Perez-Aparicio, Jose L.
    • Coupled systems mechanics
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    • 제7권1호
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    • pp.5-25
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    • 2018
  • A fully-coupled thermodynamic-based transient finite element formulation is proposed in this article for electric, magnetic, thermal and mechanic fields interactions limited to the linear case. The governing equations are obtained from conservation principles for both electric and magnetic flux, momentum and energy. A full-interaction among different fields is defined through Helmholtz free-energy potential, which provides that the constitutive equations for corresponding dual variables can be derived consistently. Although the behavior of the material is linear, the coupled interactions with the other fields are not considered limited to the linear case. The implementation is carried out in a research version of the research computer code FEAP by using 8-node isoparametric 3D solid elements. A range of numerical examples are run with the proposed element, from the relatively simple cases of piezoelectric, piezomagnetic, thermoelastic to more complicated combined coupled cases such as piezo-pyro-electric, or piezo-electro-magnetic. In this paper, some of those interactions are illustrated and discussed for a simple geometry.

상태변수 추정을 이용한 김발형 관성항법시스템의 교정기법에 대한 연구 (Calibration of gimballed inertial navigation systems using state estimation)

  • 김갑진;송택렬
    • 제어로봇시스템학회논문지
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    • 제4권1호
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    • pp.62-67
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    • 1998
  • Gimballed Inertial Navigation Systems(GINS) are sophisticated autonomous electro-mechanical systems which supply the position, velocity and attitude of the vehicle on which they are mounted. In order to maintain accuracy of outputs, the GINS are required to regularly calibrate senior errors. However, existing calibration methods take up a long time due to multiposition alignments needed to increase accuracy. A particular system formulation for calibration of a GINS is proposed to enhance system observability and thus to expedite calibration procedure. Performance of the proposed calibration method is compared with existing methods such as Schuler test and muliposition alignment. Simulation studies show the proposed system formulation associated with a suggested suboptimal filter is accurate as well as efficient in error identification essential to GINS calibration.

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도시철도용 전기기계식 제동장치의 특성시험 (Characteristic Test of the Electro Mechanical Brake Actuator for Urban Railway Vehicles)

  • 김민수;오세찬;권석진
    • 한국정밀공학회지
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    • 제33권7호
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    • pp.535-540
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    • 2016
  • The braking device in railway vehicles decelerates or stops the train by dissipating the thermal energy converted from kinetic energy into the air. Therefore, the brake system is crucial for safety. In this paper, we performed a study on an electromechanical brake actuator using an electrical motor as an alternative to pneumatic air cylinders to reduce the idle running time in braking, which subsequently increases braking distance, and to ensure reliable response characteristics. Especially, to analyze the response characteristics of the electromechanical brake actuator, we measure the delay time, response time and power consumption compared to the air cylinder. It is confirmed that the electromechanical brake actuator can reduce reaction time by 0.1 seconds (Braking Action) and 0.46 seconds (Brake Release) compared to the air cylinder.

Iron Core Design of 3-Phase 40MVA HTS Power Transformer Considering Voltages per Turn

  • Lee, Chan-joo;Seok, Bok-yeol
    • KIEE International Transaction on Electrical Machinery and Energy Conversion Systems
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    • 제4B권2호
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    • pp.54-58
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    • 2004
  • This paper presents the iron core design method of a high temperature superconducting (HTS) transformer considering voltages per turn (V/T). In this research, solenoid type HTS coils were selected for low voltage (LV) winding and double pancake coils for high voltage (HV) winding, just as in conventional large power transformers. V/T is one of the most fundamental elements used in designing transformers, as it decides the core cross sectional area and the number of primary and secondary winding turns. By controlling the V/T, the core dimension and core loss can be changed diversely. The leakage flux is another serious consideration in core design. The magnetic field perpendicular to the HTS wire causes its critical current to fall rapidly as the magnitude of the field increases slowly. Therefore in the design of iron core as well as superconducting windings, contemplation of leakage flux should be preceded. In this paper, the relationship between the V/T and core loss was observed and also, through computational calculations, the leakage magnetic fields perpendicular to the windings were found and their critical current decrement effects were considered in relation to the core design. The % impedance was calculated by way of the numerical method. Finally, various models were suggested.

이중 EHA의 제어 특성 개선 (Control-performance Improvement of Dual EHAs)

  • 이성렬;홍예선
    • 드라이브 ㆍ 컨트롤
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    • 제13권3호
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    • pp.32-38
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    • 2016
  • For this paper, the position-control performances of dual EHA(electro-hydrostatic actuator) systems were investigated according to two cases wherein the double-rod- and single-rod-type hydraulic cylinders were combined. Since the control performance is significantly dependent on the load conditions including external forces such as the inertia load, it is proposed here that the two sub-EHAs are driven by separate position and force controllers, instead of two identical position controllers. According to the simulation results, the best performance was achieved by the position-controlled single-rod-type EHA that was combined with a force-controlled double-rod-type EHA. As the force-controlled double-rod-type EHA compensated for the external loads on the position-controlled single-rod-type EHA, the position-control performance was not influenced by external forces including the inertia load. In addition, the position-controlled single-rod-type EHA contributed to the enhancement of the damping ratio by absorbing the pressure peaks through its internal accumulator. Due to the symmetrical piston areas, the double-rod-type EHA is more suitable for force control than the single-rod- type EHA.