자력 변화율 텐서를 이용한 자기 쌍극자 위치 결정

임형래 한국지구과학회 2011 한국지구과학회지 Vol.32 No.6

In this paper, I propose the algorithm that the location of a magnetic dipole can be detected from the magnetic gradient tensor. I induce the location vector of a vertically magnetizated dipole from the magnetic gradient tensor. Deficit of magnetic moment of magnetic dipole makes the induced location information incomplete. However, if the observation of magnetic gradient tensor would be collected on more points, the algorithm is able to catch the location of the magnetic dipole by clustering the solution of the proposed algorithm. For example, I show that the synthetic case of borehole observation of magnetic gradient tensor can find the source location successively by picking common solution area. 이 논문에서는 자력 변화율 텐서를 이용하여 자기 쌍극자의 위치 정보를 파악하는 알고리즘에 대하여 기술하였다. 수직으로 자화된 자기 쌍극자에 의한 자력 변화율 텐서에서 출발하여 자기 쌍극자의 위치 벡터를 유도하였다. 그러나 이 경우 자기 쌍극자의 모멘트에 대한 정보가 주어지지 않았으므로 자기 쌍극자의 위치 벡터가 불완전하게 유도된다. 이를 극복하기 위하여 여러 측정점에서 측정된 자력 변화율 텐서값이 있다고 가정하고 이를 이용하여 자동으로 자기 쌍극자의 위치를 찾아내는 알고리즘을 제안하였다. 시추공에서 자력 변화율 텐서가 측정되었다고 가정한 합성 모델실험에서 자력 변화율 텐서와 자기 쌍극자 자동 탐지 알고리즘을 이용하여 자기 쌍극자의 위치를 정확하게 찾을 수 있음을 확인하였다.

보른-인펠트형 자기쌍극자에 의한 빛의 휨

김진영 한국물리학회 2022 새물리 Vol.72 No.1

Herein, we study the bending of light by a magnetic dipole in the generalized Born–Infeld nonlinear electrodynamics. The propagation of light in a uniform magnetic field can be described by the effective index of refraction. When the background magnetic field is nonuniform, the light path bends according to the gradient of the index of refraction. Unlike the lensing by a point charge, the lensing by a magnetic dipole depends on the magnetic field strength and orientation of the magnetic dipole relative to the incoming ray. In the simplest case, where the light ray passes in the equatorial plane of the magnetic dipole, we compute the bending angle in the weak lensing limit using the trajectory equation based on geometric optics formalism. Considering the limit when the classical Born–Infeld parameter is infinite, the bending angle agrees with the result using the Euler–Heisenberg Lagrangian. Herein, we discuss the possible application to a magnetized neutron star or magnetar. 일반화된 보른-인펠트의 비선형 전자기 이론에서 자기쌍극자에 의한 빛의 휨을 연구하였다. 이 모델에서균일한 자기장 내에서 빛의 전파는 유효굴절률로 기술될 수 있다. 배경 자기장이 균일하지 않을 때빛의 경로는 굴절률의 기울기에 의해 굽어진다. 자기쌍극자에 의한 렌징은 점전하에 의한 렌징과 달리자기쌍극자에 의해 생기는 자기장의 세기뿐만 아니라 입사광에 대한 자기쌍극자의 상대적 방향성에의존한다. 빛이 자기쌍극자의 적도면에서 진행하는 가장 간단한 경우에 대해 빛의 휨각을 기하광학에기초한 궤적방정식에 사용하여 약한 렌징 근사에서 계산하였다. 고전적 보른-인펠트 매개변수가 무한대로가는 극한에서 오일러-하이젠버그의 라그랑지안을 사용하여 구한 결과와 일치함을 확인하였다. 자화된중성자별이나 자석별의 연구에 적용할 가능성을 논의하였다.

일반 물리학을 수강하는 공대생이 그린 전기쌍극자와 자기쌍극자의 장선 모양

조광희 한국물리학회 2012 새물리 Vol.62 No.8

In this study, we investigated patterns of field lines for electric dipoles and magnetic dipoles that forty four freshmen in a college of engineering drew in their introductory physics courses. According to the result, less than twenty percent of the participants, 18 \%for the electric dipoles and 16 \% for the magnetic dipoles, gave scientifically correct answers. Others showed some scientificall incongruity in their drawings. For example, some students drew field lines with wrong directions or overlapped them with junctions. In addition, several respondents did not present the proper vector sum in the space between two poles. Also, some confused the electric dipole and the magnetic dipole. These results show that more surveys and instructional improvements are needed for introductory physics courses. 이 연구에서는 일반 물리학을 수강하는 공과대학 1학년생 44명이 그린전기쌍극자와 자기쌍극자 주변의 장선 모양을 분석하였다. 분석 결과에따르면, 과학적 모형에 해당하는 사례는 전기쌍극자 18 \%, 자기 쌍극자16 \%이었다. 과학적으로 적절하지 못한 예로는 장선의 방향이 바르지않거나 겹치게 그리는 사례 등이 있었다. 그리고 두 극성 사이의공간에서 벡터 합성을 제대로 표현하지 못 하거나, 전기쌍극자와자기쌍극자를 서로 혼동하여 그리는 경향도 있었다. 이러한 결과는 일반물리학 수강생을 대상으로 전자기학 교육에 대한 전반적인 실태 조사와교수법 개발이 필요함을 시사한다.

자기쌍극자 모델을 이용한 수치해석 소프트웨어의 개발

이진이(Jiuyi Lee),이세훈(Sehoon Lee),황지성(Jiseong Hwang),전종우(Jongwoo Jun) 대한기계학회 2006 대한기계학회 춘추학술대회 Vol.2006 No.11

This paper reports a development of numerical analysis software, which could analyze magnetic field around cracks by using an improved dipole model. The preprocessor includes crack forming software, and the magnetic charge per unit area, m could be distributed on the crack section area. Also lift-off, measurement area and sensor interval, magnetization direction could be considered in the preprocessor. Also, postprocessor provides the results presenting functions, such as natural magnetic field distribution and ∂B/∂x, ∂B/∂y. Also, the physical characteristics of magnetic optical sensor and Hall sensor are included in the postprocessor, and the magnetic field distribution could be changed optical intensity and electrical signal distribution. The experiment results, which are obtained by using magnetic camera and the magnetic optical nondestructive inspection system on the crack, are compared with analysis results by using dipole model analysis software.

자기쌍극자 모델을 이용한 자기보텍스간 상호작용의 분석

심제호,전수형,오석근,유성초,김동현 한국물리학회 2010 새물리 Vol.60 No.6

We have analyzed the interaction between magnetic vortices in a ferromagnetic/non-magnetic/ferromagnetic trilayer cylinder by using a simple mathematical model. Assuming each magnetic vortex core to be a magnetic dipole, we have predicted the dynamic behavior of the magnetic-vortex coupling interaction and have confirmed that result by using a micromagnetic simulation based on the Landau-Lifshitz-Gilbert equation. 강자성/비자성/강자성 삼층박막 나노실린더에서 각 강자성층의자기보텍스간 상호작용을 간단한 수학적 모델로 분석하였다. 각강자성층의 보텍스코어 (vortex core)를 하나의 자기쌍극자 (magnetic dipole)로 보고 두 개의 자기쌍극자간 상호작용에 의한 인력을 고려하여,수정된 단순조화운동을 풀어 보텍스코어 결합운동의 동역학적 성질을예측하였다. 이러한 예측은 Landau-Lifshitz-Gilbert 방정식에 기반한마이크로자성 시뮬레이션을 통하여 확인되었다.

하지층의 스퍼터링 압력을 달리하여 제작한 Cr/CoSm/Cr 자성막의 자기상호작용과 자화역전 현상

권해웅(Hae-Woong Kweon),정순영(Soon Young Jeong),김현수(Hyeon Soo Kim) 한국자기학회 2018 韓國磁氣學會誌 Vol.28 No.3

The CoSm magnetic layer with a thickness of 30 nm was grown at a pressure of 20 mTorr on the Cr underlayer prepared with different Ar sputtering pressures. The effect of underlayer deposition conditions on magnetic interaction mechanism and magnetization reversal phenomenon was investigated. The Henkel plot, IFF and ΔM obtained from measurement curves showed that the dipole interaction was dominant in all samples, but the strength of the dipole interaction decreased with increasing sputtering pressure. In addition, all samples were found to be the dominant reversal phenomenon of the domain wall motion controlled by the domain wall pinning.

하지층 Cr의 스퍼터링 압력을 달리하여 제작한 Cr/CoSm/Cr 자성막의 자기상호작용이 자기역전부피에 끼치는 영향

권해웅(Hae-Woong Kwon),정순영(Soon Young Jeong),김현수(Hyeon Soo Kim) 한국자기학회 2018 韓國磁氣學會誌 Vol.28 No.6

Magnetic interaction effects on the magnetic switching volume for Cr/CoSm/Cr magnetic films deposited with different sputtering pressures (7~10 mTorr) of underlayer (Cr) was investigated. The magnetic interaction mechanism of all the Cr/CoSm/Cr magnetic films investigated in this study was dipole interaction, and the dipole interaction was stronger at the samples fabricated at low sputtering pressure. The magnetic field (H<SUB>ΔM</SUB>) at which the maximum dipole interaction occurred in each sample was larger than the coercivity (H<SUB>c</SUB>). The magnetic switching volume was larger for the sample with stronger dipole interaction, and it showed maximum value in the H<SUB>ΔM</SUB> region and then decreased in higher field region above the H<SUB>ΔM</SUB>. Therefore, it is considered that the intensity of the dipole interaction is closely related to the magnetic switching volume.

전기도금법으로 제작한 CoPt 자성막의 자기상호작용과 자기적 성질

김현수(Hyeon Soo Kim),이종덕(Jong Duck Lee),정순영(Soon Young Jeong),이창형(Chang Hyeong Lee),서수정(Su Jeong Suh) 한국자기학회 2011 韓國磁氣學會誌 Vol.21 No.5

The influence of thickness on magnetic interaction and magnetic properties in electrodeposited CoPt magnetic films was investigated from the analysis of the magnetic remanence curves and the magnetic hysteresis loops. As the thickness of the CoPt film is increased, the perpendicular coercivity and the saturation magnetization are increased but the squareness is considerably decreased. The analysis results of the magnetic remanence curves and the magnetic hysteresis loops exhibited that the dipolar interaction is the main interaction mechanism for all samples, but the strength of the dipolar interaction gradually increased with increasing sample thickness.

등가 자기모델과 매질민감도법을 이용한 강자성체 판에 분포하는 영구자화에 기인한 자기장 신호분석

정기우(Gi-Woo Jeung),김동욱(Dong-Wook Kim),김동훈(Dong-Hun Kim),양창섭(Chang-Seob Yang),정현주(Hyun-Ju Chung) 한국자기학회 2010 韓國磁氣學會誌 Vol.20 No.3

For predicting magnetic signals due to the remanent magnetization distributed on a ferromagnetic ship hull, this paper presents an efficient methodology for solving inverse problems, where the material sensitivity analysis based on the continuum mechanics is combined with the equivalent magnetic models. To achieve this, the 3D magnetic charge model and the magnetic dipole moment model are introduced and material sensitivity formulae applicable to each equivalent model are derived. The formulae offer the firstorder gradient information of an objective function with respect to the variation of the magnetic charge or magnetic dipole and so an optimal solution can be easily obtained regardless of the number of design variables. To validate the proposed method, the numerical results are comparison with the real measurements of a mock-up model.

결함주변 자기량 변화를 이용한 자기쌍극자 모델의 개선

황지성(Jiseong Hwang),전종우(Jongwoo Jun),이진이(Jinyi Lee) 대한기계학회 2006 대한기계학회 춘추학술대회 Vol.2006 No.11

Nondestructive testing using a magnetic field is useful for detect a crack on the ferromagnetic material. The magnetic field distribution has to be obtained for evaluate a crack direction, size and shape quantitatively. Also, the crack could be evaluated by using inverse problem analysis. Conversely, an analysis method using a dipole model has analyzed the magnetic field distribution around a crack with higher speed than finite element method (FEM). Therefore a dipole model simulation could propose the useful information which is used for the inverse problem analysis. However the magnetic charge per unit area, m and the permeability, μ have been treated as constants up to now. Correspondingly, the analyzed results were different with the experimental results at a lot of cases. This paper proposes the improved dipole model simulation method, which is assumed that m is given more weight at the edge line of crack. The propriety of the improved method is verified by comparing with magnetic camera experiment results.