• 대한전기학회:학술대회논문집
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• 대한전기학회 1999년도 하계학술대회 논문집 A
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• pp.160-163
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• 1999

The thrust force of moving magnet-type linear direct current motors(MM-LDM) is analyzed in this study. A moving magnet-type LDM consists of a stator and a carriage. The stator is composed of two stick shaped electro magnetics and the carriage consists of a movable permanent magnet that is located between the two electromagnets. The method for calculating the thrust force of an MM-LDM is to analyze the energy gradient which is determined by the distribution of magnetic flux. And this paper describes the development of the generalized machine theory for d.c. linear motors and its application to determine the motor parameters.

• 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.

• 한국정보통신학회:학술대회논문집
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• 한국정보통신학회 2015년도 추계학술대회
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• pp.468-470
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• 2015

EMP(ElectroMagnetic Pulse)는 미국이 태평양에서 실시한 수소폭탄 실험에서 처음으로 그 존재가 발견되었다. 핵무기는 열과 폭발력으로 인명을 살상하는 무기이지만, 우연히 발견된 EMP는 인명의 손상 없이 전자장비에 치명적인 손상을 가할 수 있는 무기체계로 활용될 수 있으며, 특히 컴퓨터 등 전자장치에 의해 작동되는 자동화 무기체계를 효과적으로 무력화 할 수 있다. 따라서 주요 군사시설은 EMP로부터 보호되는 설비가 필수적으로 구비되고 있다. 본 논문에서는 EMP의 개념에 대해 설명하고, EMP로부터 보호하기 위한 대응 방안에 대해 조사하여 기술하였다.

• 전기학회논문지
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• 제66권12호
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• pp.1782-1791
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• 2017

In this paper, an optimal design of hybrid magnetic levitation(Maglev) system using intelligent optimization algorithms is proposed. The proposed maglev system adopts hybrid suspension system with permanent-magnet(PM) and electro magnet(EM) to reduce the suspension power loss and the teaching-learning based optimization(TLBO) that can overcome the drawbacks of conventional intelligent optimization algorithm is used. To obtain the mathematical model of hybrid suspension system, the magnetic equivalent circuit including leakage fluxes are used. Also, design restrictions such as cross section areas of PM and EM, the maximum length of PM, magnetic force are considered to choose the optimal parameters by intelligent optimization algorithm. To meet desired suspension power and lower power loss, the multi object function is proposed. To verify the proposed object function and intelligent optimization algorithms, we analyze the performance using the mean value and standard error of 10 simulation results. The simulation results show that the proposed method is more effective than conventional optimization methods.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2003년도 추계학술대회 논문집 전기기기 및 에너지변환시스템부문
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• pp.137-140
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• 2003

To the optimization design of molded case circuit breakers(MCCBs), it is necessary and important to calculate the electro-dynamic repulsion force acting on the movable conductor. With 3-D finite element nonlinear analysis, according to the equations among current-magnetic field-repulsion force and taking into account the ferromagnet, contact bridge model is introduced to simulate the current constriction between contacts, so Lorentz and Holm force acting on the movable conductor and contact, respectively, can be integrated to calculate. Coupled with circuit equations, the opening time of movable contact also can be obtained using iteration with the restriction of contact force. Simulation and experiment for repulsion forte and opening time of five different configuration models have been investigated. The results indicate that the proposed method is effective and capable of evaluating new design of contact systems in MCCBs.

• Journal of Welding and Joining
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• 제25권2호
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• pp.49-54
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• 2007

Since the wall thickness can be up to 6" or greater, welds must be made in many layers, each layer containing several passes. However, the welding time for the conventional welding processes such as SAW(Submerged Arc Welding) and FCAW(Flux Cored Arc Welding) can be required many hours. The aim of this paper is to develop a high speed welding system with multi-torch and laser vision sensor for increasing the production speed on the line and to remove the need for the operator so that the system can run automatically for the complete multi-torch multi-layer weld. It was shown that the developed laser vision sensor and analysis of arc blow for multi-torch were effective for multi-pass seam tracking and stable arc. A new automated multi-torch welding systems for thick wall applications has been proved in several production lines.

• Journal of international Conference on Electrical Machines and Systems
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• 제3권4호
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• pp.487-490
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• 2014

The conventional motor-driven MCCB (molded-case circuit breaker) is not only large in size, but also inefficient in performance. To solve these problems, this paper suggests SPMA (separate permanent-magnet actuator), a novel magnetic actuator. In this paper, SPMA is designed for a 225AF MCCB and compared to a conventional motor-driven MCCB and to an EMFA (electro-magnetic force driving actuator)-type MCCB.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1995년도 추계학술대회 논문집 학회본부
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• pp.49-51
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• 1995

This paper deals with the magnet for Urban Transit Maglev-01 (Electro-Magnetic Suspension) which is experimented by the static magnet test bed. The test bed is developed for the hinge style. This paper shows the levitation force vs magnet current and difference of the yoke depth.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2008년도 제39회 하계학술대회
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• pp.872-873
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• 2008

In this paper, a new type of switchgear, electro magnetic force driving actuator (EMFA), is developed and analyzed, applicable to high voltage gas circuit breaker (HGCB). Transient analysis is performed in order to obtain the dynamic characteristics of the EMFA. The distribution of static magnetic flux is obtained using the finite element method (FEM). The governing electric and kinematical equations are solved using the time difference method (TDM). Fabrication and experiments were performed in order to prove the applicability of HGCB for overall class. In comparing the experiment with simulated data, it is confirmed that analysis of the dynamic characteristics of EMFA is appropriate for design.

• Smart Structures and Systems
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• 제2권1호
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• pp.61-80
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• 2006

The concept of structural vibration control is to absorb vibration energy of the structure by introducing auxiliary devices. Various types of structural vibration control theories and devices have been recently developed and introduced into mechanical systems. One of such devices is damper employing controllable fluids such as ElectroRheological (ER) or MagnetoRheological (MR) fluids. MagnetoRheological (MR) materials are suspensions of fine magnetizable ferromagnetic particles in a non-magnetic medium exhibiting controllable rheological behaviour in the presence of an applied magnetic field. This paper presents the modelling of an MRfluid damper. The damper model is developed based on Newtonian shear flow and Bingham plastic shear flow models. The geometric parameters are varied to get the optimised damper characteristics. The numerical analysis is carried out to estimate the damping coefficient and damping force. The analytical results are compared with the experimental results. The results confirm that MR damper is one of the most promising new semi-active devices for structural vibration control.