• Title/Summary/Keyword: Yield electric field

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A Study of the Hydraulic Circuit Model for a Magnetorheological Damper Analysis (MR 댐퍼 해석을 위한 유압회로 모델에 대한 연구)

  • Chang, Moon Suk;Byeon, Woo Jin;Kim, Soo Tae;An, Chae Hean
    • Journal of Drive and Control
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    • v.14 no.1
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    • pp.8-13
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    • 2017
  • This paper proposes a hydraulic circuit for a Magnetorheological (MR) damper that can be used for semi-active and active controls. Methods are presented for obtaining reliable damping force displacement and velocity data, and hysteresis loop data corresponding to applied current. In order to get reliable data, analysis using electric and electronic software, a series of tests. and comparative evaluations are required. A hydraulic circuit model is proposed that can be applied to analyze a MR damper without any assumptions where the yield stress data according to the applied current are known. Analysis results of the proposed hydraulic circuit are confirmed by experimental results within acceptable tolerance. This hydraulic circuit model can be applied to various MR dampers and systems.

Effect of High Voltage Pulsed Electric Fields on Extraction of Purple Sweet Potato Pigment (자색 고구마 색소의 추출에 미치는 고전압 펄스 전기장의 영향)

  • Shin, Jung-Kue;Shin, Hae-Hun
    • Food Science and Preservation
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    • v.14 no.2
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    • pp.165-169
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    • 2007
  • High voltage pulsed electric fields (PEF) is a promising technology for the nonthermal extraction of effective components from biological materials. Plant cells were ruptured with PEF at ambient or refrigerated temperature for a short treatment time of second or microsecond. Treatments of coarsely ground purple sweet potato (PSP) with PEF(30 kV/cm, 500 Hz) resulted in maximum extraction yield of 65% as compared with 45-50% for control. An increase in electric field strength (from 10kV/cm to 35kV/cm) and frequency (from 100Hz to 500Hz) resulted in increased amount of extracted pigments, but treatment time is not affected on pigment extraction. Starch granules were not detected and large intracellular spaces were visible between the cells on light and scanning election microscopy of PEF treated PSP. This result suggests that PEF have potential to use on extraction of pigments from plant cells.

Position Control of an ER Valve-Cylinder System (ER 밸브-실린더 시스템의 위치 제어)

  • 이효정;정재민;박재석;최승복;정재천
    • Proceedings of the Korean Society of Precision Engineering Conference
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    • 1993.10a
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    • pp.402-405
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    • 1993
  • This paper presents design.dynamic modeling and control issues of a novel type of an ER valve-cylinder system incorporating with an electro-rheological(ER) fluid. The yield stress of the ER fluid to be employed to the proposed system is evaluated as a function of applied electric fields. The design and manufacturing process of the ER valve which features fast system response and simple mechanism are undertaken on the basis of model parameters. The governing equation for the hydraulic and pneumatic model is constructed by incorporation with the field-dependent Bingham behavior of the ER fluid. An effective neuro controller is proposed to realize an accurate position control.

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Characteristics of Directional Squeeze Film Damper Using ER Fluid (ER유체를 이용한 이방성 스퀴즈필름 댐퍼의 특성)

  • 안영공;양보석;삼하신
    • Journal of KSNVE
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    • v.11 no.2
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    • pp.301-306
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    • 2001
  • Electro-Rheological (ER) fluid is applied to a controllable squeeze film damper (SFD) for stabilizing a flexibly supported rotor system. ER fluid is a class of functional fluid whose yield stress varies according to the applied electric field strength, which is observed as viscosity variation of the fluid. In applying ER fluid to a SFD, a pair of rings of the damper can be used as electrodes. When the electrodes are divided into a horizontal pair and a vertical one, the SFD can produce damping force in each direction independently. A prototype of the directionally controllable SFD was constructed and its performance was experimentally and numerically investigated in the present work.

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Polymer Light-Emitting Diodes Based on Poly(3-hexyl thiophene)

  • Chang, Seoul;Kim, Nam-Hee
    • Fibers and Polymers
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    • v.1 no.1
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    • pp.25-31
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    • 2000
  • Poly(3-hexyl thiophene)(P3HT) and poly(3-dodecyl thiophene)(P3DT) were polymerized by oxidative coupling with ferric chloride. The P3HT light-emitting device emitted red light and it could be observable in the ordinary indoor light. The device had the turn-on electric field of about 3$\times$$10^7$ V/m. The maximum electroluminescene (EL) intensity was obtained when the thickness of polymer layer was about 130 nm in IT0/P3HT/Al device. The maximum external quantum yield was 0.002%. The maximum luminance was 21 cd/$m^2$. The EL intensity decreases with increasing the crystallinity of the polymer layer. By using the oriented poly(3-alkyl thiophene)(PAT) layer as an electroluminescent layer in the ITO/polymer/Al light-emitting devices, the polarized EL light emission was observed. The EL intensity ratio of parallel to perpendicular direction to the stretch direction for P3HT was about 1.40.

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Influence of Bingham Characteristics for ER Fluid on Semi-Active Suspension System (ER유체의 역학적 특성이 반능동 현가시스템에 미치는 영향)

  • 김옥삼;김일겸;조남철;박우철
    • Journal of Advanced Marine Engineering and Technology
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    • v.28 no.3
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    • pp.434-440
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    • 2004
  • The electro-rheological fluids for semi-active suspension system are a class of colloidal dispersion which exhibit large reversible changes in their rheological behavior when they are subjected to external electrical fields. This paper presents Bingham properties of ER fluids subjected to temperature variations. In addition, an appropriate size of the ER damper for a passenger car is proposed to investigate the effects of Bingham characteristics on the damping performance. The filed-dependent damping forces are evaluated according to the temperature variation and sedimentation ratio.

Performance Analysis of Smart Impact Damper (지능형 완충기의 특성 해석)

  • ;;Y.T. Choi
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2001.05a
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    • pp.323-327
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    • 2001
  • Electrorheological(ER) and magnetorheological(MR) fluids have a unique ability to increase the dynamic yield stress of the fluid substantially when electric or magnetic field is applied. Controllable fluids such as ER and MR fluids have received considerable attention as several components of engineering devices. One of them is a smart impact damper using ER/MR fluids. Impact damper system can be used in the joint mechanism of railroad vehicle, protection equipment of elevator's drop, and launch equipment of aircraft. This paper presents the results of an analytical study of the performance of a smart impact damper to suppress vibration during impact excitation. The damping capabilities of MR impact damper for variable applied current are analyzed using Bingham model under sudden impact load.

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Active Tension Control Using an ER Brake Actuator (ER브레이크 작동기를 이용한 능동 장력 제어)

  • Park, S.B.;Kim, G.W.;Cheong, C.C.
    • Journal of the Korean Society for Precision Engineering
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    • v.13 no.8
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    • pp.102-111
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    • 1996
  • This paper presents a proof-of-concept investigation on an active tension control using an ER (electro-rheological) brake actuator. Firstly, an ERF (electro-rheological fluid) which has an inherent reversible feature from Newtonian fluid to Bingham fluid upon applying an electric field is composed, and its property is tested to obtain intrinsic parameters of the Bingham model. An appropriate size of the ER brake is manufactured on the basis of the Bingham model, and dynamic characteristics of the brake are experimentally identified. After formulating a governing equation of motion of the tension control system, a sliding mode controller is designed to achieve a certain desired level of tension. Both simulation and experimental works are undertaken in order to demonstrate the efficiency and feasibility of the proposed active tension control method.

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Mechanical Durability of ER Fluids and Performance Investigation of ER Dampers (ER유체의 기계적 내구성 및 ER댐퍼의 성능고찰)

  • 박우철;최승복;정재천;서문석;강윤수;여문수
    • Proceedings of the Korean Society of Precision Engineering Conference
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    • 1996.11a
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    • pp.1044-1047
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    • 1996
  • This paper presents durability characteristics of electrorheological(ER) fluids which undergo a reversible phase change depending upon the imposition of electric fields. The field-dependent Bingham properties are subjected to be altered from long time use of the ER fluid. The level of the changed properties depends upon employed device and test conditions. A piston-rod system which has same mechanism as ER dampers is adopted in this study and tested by increasing operation cycle up to 1 million. Bingham properties of initial and us ER fluids are tested and compared. In addition, these ER fluids are applied to ER damper in order to evaluate damping force performance.

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A Novel Technique for Current Density Distribution Analysis of Solidly Modelled Coil (Solid 모델링된 코일의 전류 밀도 분포 해석을 위한 새로운 방법)

  • Im, Chang-Hwan;Kim, Hong-Gyu;Jeong, Hyeon-Gyo
    • The Transactions of the Korean Institute of Electrical Engineers B
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    • v.49 no.7
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    • pp.483-487
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    • 2000
  • The analysis of current distribution in a solidly modeled coil is very important for accurate of electric machines such as deflection yoke. In general, Modeling every coils is nearly impossible for analyzing magnetic field using the 3-D finite element method, so solidly modeled coil is usually used. Some methods have been developed for analyzing current distribution, but these methods have fatal disadvantages. The main disadvantages are that the methods cannot be applied to an arbitrary shaped coil and that they yield numerical errors. In this paper, a novel method for resolving the problems mentioned above is proposed. The new method is verified by the application to a test model and it shows a very accurate result.

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