• 한국자기학회:학술대회 개요집
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• 한국자기학회 2007년도 동계학술연구발표회 및 스핀트로닉스와 나노물리에관한 국제심포지움
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• pp.176-176
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• 2007

• Journal of Magnetics
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• 제19권4호
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• pp.315-322
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• 2014

In this work, Artificial Neural Network (ANN) was used to model the dynamic behavior of ferromagnetic hysteresis derived from performing the mean-field analysis on the Ising model. The effect of field parameters and system structure (via coordination number) on dynamic critical points was elucidated. The Ising magnetization equation was drawn from mean-field picture where the steady hysteresis loops were extracted, and series of the dynamic critical points for constructing dynamic phase-diagram were depicted. From the dynamic critical points, the field parameters and the coordination number were treated as inputs whereas the dynamic critical temperature was considered as the output of the ANN. The input-output datasets were divided into training, validating and testing datasets. The number of neurons in hidden layer was varied in structuring ANN network with highest accuracy. The network was then used to predict dynamic critical points of the untrained input. The predicted and the targeted outputs were found to match well over an extensive range even for systems with different structures and field parameters. This therefore confirms the ANN capabilities and indicates the ANN ability in modeling the ferromagnetic dynamic hysteresis behavior for establishing the dynamic-phase-diagram.

• Journal of Magnetics
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• 제20권4호
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• pp.394-399
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• 2015

Electromagnetic Induction Launchers (EIL) have been receiving great attention due to their advantages of non-contact between the coils and a projectile. This paper describes the modeling and design of 3-stage EIL to accelerate a copper projectile of 50 kg with 290 mm diameter. Our EIL consists of three independent driving coils and pulsed power modules to generate separate driving currents. To find efficient acceleration conditions, the appropriate shape of the driving coils and the position of the projectile have been calculated by using a finite element analysis (FEA) method. The results showed that the projectile can be accelerated more effectively as the gap between the coils is smaller; a final velocity of 45 m/s was obtained. The acceleration efficiency was estimated to be 23.4% when a total electrical energy of 216 kJ was discharged.

• Journal of Magnetics
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• 제20권3호
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• pp.284-289
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• 2015

This paper discusses general methods of modelling magnetic saturation in steady-state, two-axis (d & q) frame models of dual stator induction generators (DSIG). In particular, the important role of the magnetic coupling between the d-q axes (cross-magnetizing phenomenon) is demonstrated, with and without cross-saturation. For that purpose, two distinct models of DSIGs, with and without cross-saturation, are specified. These two models are verified by an application that is sensitive to the presence of cross-saturation, to prove the validity of these final methods and the equivalence between all developed models. Advantages of some of the models over the existing ones and their applicability are discussed. In addition, an alternative is given to evaluate all saturation factors (static and dynamic) by just calculating the static magnetizing inductance which is simply the magnitude of the ratio of the magnetizing flux to the current. The comparison between the simulation results of the proposed model with experimental results gives a good correspondence, especially at startup.

• 한국자기학회지
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• 제22권6호
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• pp.195-199
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• 2012

전산모사를 이용하여, 자기소용돌이의 공진 주파수에 대한 두께 의존성을 조사하였다. 자기소용돌이의 공진 주파수는 2차원(2D)과 3차원(3D) 계산결과 모두 두께가 두꺼워짐에 따라 증가하는 경향을 보였다. 그러나 2D와 3D 계산 결과는 두께가 두꺼워짐에 따라 차이를 보였는데, 이는 3D 계산과 달리 2D 계산에서는 두께가 증가함에 따라 두께방향으로 발생하는 불균질한 자화 구조를 고려하지 않았기 때문이다.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2004년도 전력전자학술대회 논문집(2)
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• pp.902-905
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• 2004

Characteristics of electrodelss lamp as a load of the ballast is different compared to normal fluorescent lamp because the lamp includes the magnetics for inductive discharging process. So somewhat different modeling is necessary to make a proper power match between the lamp and ballast. Modeling of an electrodeless lamps, Endura of Osram, is presented in this paper. Simulation with a result of experiment is given for a verification of proposed model.

• 한국조명전기설비학회:학술대회논문집
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• 한국조명전기설비학회 2004년도 춘계학술대회 논문집
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• pp.131-134
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• 2004

Characteristics of electrodelss lamp as a load of the ballast is different compared to normal fluorescent lamp because the lamp includes the magnetics for inductive discharging process. So somewhat different modeling is necessary to make a proper power match between the lamp and ballast. Modeling of an electrodeless lamps, Endura of Osram, is presented in this paper. Simulation with a result of experiment is given for a verification of proposed model.

• Journal of Magnetics
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• 제19권1호
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• pp.43-48
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• 2014

Magnetic materials with large coercive force and high squareness ratio are currently developing to meet an industrial demand. Since a ferromagnetic material has hysteresis characteristics, it is hard to demagnetize a ferromagnetic material precisely. In this paper, we describe deperm processes and conduct an analysis of residual magnetization of ferromagnetic material using the Preisach modeling with a two-dimensional finite elements method (FEM). From the results, it was shown that an exponential decrement form of deperm protocol is more efficient than a linear decrement form because of the demagnetizing field in the ferromagnetic material.

• Journal of Magnetics
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• 제5권2호
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• pp.27-34
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• 2000

The structure of a series of Cu/Ni is characterized by using a program, SUPREX, to model the x-ray diffraction patterns, multilayers. The samples had nominal layer thickness of 3/3, 7/7, 13.5/13.5, 20/20, 30/30, 50/50, 80/80, 100/100, and 200/200 Angstroms. The diffraction patterns were taken around the (111) peak for the two constituent materials. A kinematical model is used to characterize the diffraction patterns and the parameters for the model are described. An initial model is calculated using initial guesses for the parameters. The model is then fit to the data by reducing $x^2$using the Levenberg-Marquardt algorithm. The samples are shown to be high quality supperlattices.

• Journal of Magnetics
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• 제20권4호
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• pp.460-465
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• 2015

The paper presents methodologies and results concerning one- and two-dimensional numerical modeling of radio frequency oscillations in a coaxial transmission line fed with a short pulse of electric current. The line is partially filled with a ferrite material, magnetized longitudinally close to saturation. The 2D model has permitted analyzing, for the first time in the art, the spatial structure and dynamics of the wave field within the radially non-uniform cross-section planes of the non-linear and dispersive guiding structure. This opens ways for optimizing size parameters of the line and the extent to which it is filled with the ferromagnetic material, thus increasing the line's electric strength and intensity of the r.f. oscillations.