• Nuclear Engineering and Technology
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• 제40권3호
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• pp.213-224
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• 2008

The pumping of coolant in a liquid metal fast reactor may be performed with an annular linear induction electro-magnetic (EM) pump. Linear induction pumps use a traveling magnetic field wave created by poly-phase currents, and the induced currents and their associated magnetic field generate a Lorentz force, whose effect can be the pumping of the liquid metal. The flow behaviors in the pump are very complex, including a time-varying Lorentz force and pressure pulsation, because an induction EM pump has time-varying magnetic fields and the induced convective currents that originate from the flow of the liquid metal. These phenomena lead to an instability problem in the pump arising from the changes of the generated Lorentz forces along the pump's geometry. Therefore, a magneto-hydro-dynamics (MHD) analysis is required for the design and operation of a linear induction EM pump. We have developed a time-harmonic 2-dimensional axisymmetry MHD analysis method based on the Maxwell equations. This paper describes the analysis and numerical method for obtaining solutions for some MHD parameters in an induction EM pump. Experimental test results obtained from an induction EM pump of CLIP-150 at the STC "Sintez," D.V. Efremov Institute of Electro-physical Apparatus in St. Petersburg were used to validate the method. In addition, we investigated some characteristics of a linear induction EM pump, such as the effect of the convective current and the double supply frequency (DSF) pressure pulsation. This simple model overestimated the convective eddy current generated from the sodium flow in the pump channel; however, it had a similar tendency for the measured data of the pump performance through a comparison with the experimental data. Considering its simplicity, it could be a base model for designing an EM pump and for evaluating the MHD flow in an EM pump.

• Journal of information and communication convergence engineering
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• 제8권1호
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• pp.95-98
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• 2010

The Electro Magnetic (EM) Acceleration and Deceleration (ACC/DCC) system of the Ferromagnetic Ball(FB) is the linear motor's final structural development which can be used for devices that conserve energy, gaming or rail gun. By accelerating the FB within the coil structure, it is difficult to utilize the FB's magnetizing feature via the ACC/DCC system. There is much monopole space inside the monopole coil. By using this particular feature of the FB, starting coil and Monopole Coil Structure (MCS) can be structurally separated and another simple electric related control system can be experimented for further development. For the purpose of development a review is needed of the control system of both basic stepper motor and BLDC motor.

• 한국소음진동공학회논문집
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• 제20권12호
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• pp.1128-1138
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• 2010

정밀 방진에서 전형적인 문제로 고하중으로 인한 저주파 공진 특성이 있다. 전자기 에어 스프징은 진동 제어 장치이자 능동형 방진 장치이다. 이 연구에서 전자기 에어 스프링은 반도체 생산을 위한 저주파 공진을 제거하는 것을 목적으로 한다. 능동형 방진 장치로 기계 및 전가 부분은 2.5톤의 하 중에 작동되도록 설계하였다. 전자기 스프링은 탄성 공압 챔버 내에 공기압을 이용하여 띄우고, 전자기 된 시스템에 의하면 공진 주파수 영역에서 제어 시간 및 최고 피크가 상당히 줄어들었고, 그 결과 피동형 시스템 상의 고유 진동에 의해 발생되는 공진을 피할 수 있음을 보였다.

• International Journal of Automotive Technology
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• 제8권4호
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• pp.429-436
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• 2007

In this study, we improved control performance of an EMV (electromechanical valve) system using a PM/EM (permanent magnet/electromagnet) hybrid EMA (electromagnetic actuator) and showed the feasibilities of both soft landing and fast transition of the EMV system using a simple PID control. The conventional EMV systems using only EM show significant nonlinear characteristics. Therefore, it is very difficult to control the valve position and several complex control schemes are used. This paper focused on the control performance improvement using a PM/EM hybrid actuator. In particular, a PM is used as a key design parameter such as a bias current of a magnetic bearing in order to improve the linear characteristic of the actuator, although most PM/EM hybrid actuators use a PM as a power saver during valve-open and -closed states. First, a FE (finite element) analysis was performed to confirm its linear static force characteristics. Then, both a test rig and a valve control system were built in order to prove experimentally the control performance improvement of the actuator. Finally, feasibilities of both soft landing and fast transition of the system were shown experimentally through gain-scheduled PID (proportional derivative integral) control.

• 제어로봇시스템학회논문지
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• 제19권2호
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• pp.107-112
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• 2013

In this paper, we discuss a 3-dimensional localization sensor node using EM waves (Electromagnetic waves) with RSSI (Received Signal Strength Indicator). Generally EM waves cannot be used in underwater environment, because the signal is highly attenuated by the water medium according to the distance. Although the signal quickly reduces in underwater, the reducing tendency is very clear and uniform. Hence EM waves have possibility as underwater distance sensors. The authors have verified the possibility by theory and several experiments, and developed calibration methods in case of linear and planer environment. For 3-dimensional localization in underwater, it must be known antenna's radiation pattern property in electric plane(called E-plane). In this paper, we proceed experiments to verify attenuation tendency with z axis movement, PLF (Polarization Loss Factor) and ILF (Inclination Loss Factor) with its theoretical approach.

• 한국전자파학회논문지
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• 제26권2호
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• pp.189-195
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• 2015

전자기파 시뮬레이션을 통해 SAR 영상을 생성하는 방법은 그동안 많은 연구가 이루어져 왔다. 특히, SAR(Synthetic Aperture Radar) 영상 생성 전용 분석 S/W가 있긴 하지만, 대부분 국방 및 보안 특성상 일반인들에게 공개되지 않고 있다. 본 논문에서는 범용 EM(Electro Magnetic) simulator를 이용하여 다양한 방법으로 사실적 표적 모델을 분석하는 방법에 대해 설명한다. 특히, 역합성 개구면 레이다(inverse synthetic aperture radar) 영상을 생성하고, 처리하는 방법을 설명한다. 이 방법을 잘 활용하면, 막대한 비용이 들어가는 수많은 실제 표적들에 대한 표적 인식(target recognition) 데이터베이스 구축을 상대적으로 저렴하고 시간효율적으로 수행할 수 있게 된다.

• 대한자원환경지질학회:학술대회논문집
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• 대한자원환경지질학회 2003년도 춘계 학술발표회 논문집
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• pp.150-153
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• 2003

High-resolution imaging of electrical conductivity has been the subject of many studies in crosshole tomography using electromagnetic (EM) fields (Zhou et al., 1993; Wilt et al., 1995; Alumbaugh and Morrison, 1995; Newman, 1995; Alumbaugh and Newman, 1997). Although the theoretical understanding and associated field practices for crosshole EM methods are relatively mature, fast and stable imaging of crosshole EM data is still a challenging problem. (omitted)

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2009년도 하계학술대회 논문집
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• pp.46-47
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• 2009

In this paper, a power combiner using IPD process for SK Telecom 3-Generation (2.13 ~ 2.15 GHz) application. The Integrated Passive Device (IPD) Wilkinson power Combiner shows compact size and high performance. It is simulated by 3D Electro Magnetic (EM) simulation because of more accurate measurement result wire-bonding effects. This combiner exhibit size of $1.2mm^2$ the insertion loss of 3.6 dB, and the return loss of 10.1 dB, and isolation of more than -7.7 dB.

• 한국전자파학회논문지
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• 제22권12호
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• pp.1086-1096
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• 2011

본 논문에서는 중심 주파수 2.44 GHz, 상대 대역폭 5 %, 반사 손실 18 dB, 전달 영점 주파수 2.63 GHz을 갖는 트라이섹션 대역 통과 여파기를 다중 포트 EM(ElectroMagnetic) 시뮬레이션을 이용한 설계를 보인다. 교차 결합(cross-coupling)이 포함된 트라이섹션 여파기 결합 행렬을 계산하고, 여파기를 무손실 2-포트 회로로 변환하여 기준형 등가 회로를 결정한다. 여파기 설계를 위해 개별 공진기로 분해한 후 다중 포트 EM 시뮬레이션으로 얻어진 Y-파라미터에서 J-인버터와 서셉턴스 기울기를 기준형 등가 회로의 J-인버터 및 서셉턴스 기울기에 정합하여 여파기 설계 치수들을 결정하게 된다. 결정된 물리적 치수로 구성된 여파기는 결합 행렬에서 고려하지 않은 결합으로 주파수 응답 특성이 기준형 등가 회로에 비해 다소 차이를 보이게 된다. 여파기 응답 특성의 최적화를 위해 초기 설계 치수를 변화시켜 여파기의 EM 시뮬레이션 결과들을 모아 회로에서 최적화하여 최종 설계 치수를 얻는다. 최종 설계 치수를 갖는 여파기를 제작하여 트라이섹션 여파기 설계 방법의 타당성을 검증하였다.

• 한국전산구조공학회:학술대회논문집
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• 한국전산구조공학회 2007년도 정기 학술대회 논문집
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• pp.669-674
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• 2007

To develop a promising hybrid structural health monitoring (SHM) system, a combined use of structural vibration and electro-mechanical (EM) impedance is proposed. The hybrid SHM system is designed to use vibration characteristics as global index and EM impedance as local index. The proposed health monitoring scheme is implemented into prestressed concrete (PSC) girder bridges for which a series of damage scenarios are designed to simulate various prestress-loss situations at which the target bridges car experience during their service life. The measured experimental results, modal parameters and electro-magnetic impedance signatures, are carefully analyzed to recognize the occurrence of damage and furthermore to indicate its location.