• Journal of the Korean Magnetics Society
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• v.20 no.5
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• pp.201-205
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• 2010

X-ray magnetic circular dichroism (XMCD) has been used as an important tool of magnetics due to its unique abilities to measure element-specific magnetic properties and to separate the orbital and the spin magnetic moments. These abilities allow researchers to access the microscopic origin of the magnetic properties of transition metal and rare earth compounds. In this report, I explain the principle of XMCD and the experimental set-up. Recent a few research examples using XMCD will be also introduced.

• Aerospace Engineering and Technology
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• v.4 no.2
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• pp.101-106
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• 2005

KOMPSAT-2 위성에서 사용되는 TAM의 정상적인 작동을 위해 각 유닛에서 생성되는 자기장(magnetic field) 값은 일정한 양 이하가 되도록 관리되고 있다. 자기장은 그 특성상 전장품 간의 거리에 반비례하며 전장품의 자기 모멘트에 비례하므로 위성체 유닛의 자기장 값을 관리하기 위해 우선 유닛의 magnetic moment 값을 구해야한다. KOMPSAT-2의 각 전장품들의 자기 모멘트 값은 기존 KOMPSAT-1의 값을 근거로 설정되었다. 이것은 KOMPSAT-2가 KOMPSAT-1의 heritage를 따라 설계되었으며 각 전장품 역시 KOMPSAT-1 전장품 설계를 대부분 따르고 있기 때문이다. 그리고 최근 EMC 해석 S/W중 magnetic moment를 전문적으로 해석해주는 tool이 출시되었다. 이 tool은 해석하고자 하는 유닛의 geometric 정보와 전류 패스를 설정하면 자기 모멘트 값을 구할 수 있는 수식을 풀어내 그 값을 알려준다. 본 논문에서는 magnetic moment 값을 구할 수 있는 수식이 이 tool에 어떻게 구현되었는지 살펴보고 실제 KOMPSAT-2의 전장품의 자기 모멘트 해석 결과를 보여준다.

• Journal of the Korean Magnetics Society
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• v.2 no.3
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• pp.193-199
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• 1992

희토류 영구자석, $Nd_2Fe_{14}B$ 화합물에 대한 자체충족적 국재밀도함수근사 전자 구조 계산을 수행하여 이 물질의 전자기적 물성을 연구하였다. LMTO(Linearized Muffin-Tin Orbital)에너지 띠 방법을 사용하여 상자성, 강자성상에서 구한 $Nd_2Fe_{14}B$ 화합물의 에너지 띠구조를 토대로 하여 자성을 포함한 제반 물성, 즉 희토류금속과 천이금속의 결합(bonding)효과, 전기적, 자기적 구조등을 고찰하였다. Boron 원자의 역학은 근접 Fe 원자와의 혼합 상호작용을 통하여 Fe의 원자의 자기모멘트를 많이 줄이는 효과를 주며 또한 구조 안정성에 기여한다는 결과를 얻었다. 강자성상에서의 Fe 원자들의 평균 자기모멘트는 약 2.15 ${\mu}B$로 계산되었는데 이중 Boron 원자로 부터 가장 멀리 떨어져 있으며 12개의 Fe 원자들로 둘러싸인 Fe(j2-site)원자가 가장 큰 값(2.7 ${\mu}B$)의 자기모멘트를 갖고 Boron 원자와의 혼합 상호작용이 가장 큰 Fe(e-site)원자가 가장 작은 값(1.9 ${\mu}B$)의 자기모멘트를 갖는다.

• Journal of the Korean Chemical Society
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• v.24 no.2
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• pp.91-100
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• 1980

A formula for calculation of the magnetic moments for octahedral $[Ti(III)A_3B_3]$ type complexes with axial symmetry has been developed and the magnetic moments for these complexes are calculated, using the experimental values of the distortion parameters$({\delta})$, spin-orbit coupling constants and orbital reduction factors. The calculated magnetic moments for axially distorted octahedral $[Ti(III)A_3B_3]$ type complexes are in resonable agreement with the experimental valuest It is found that the calculated magnetic moments decrease as the extent of axial distortion increases and the orbital reduction factor decreases. A calculation method of the magnetic moments for octahedral $[Ti(III)A_3B_3]$ type complexes which are in a ligand field of lower than axial symmetry has also been developed and the structure of distorted octahedral $[Ti(III)A_3B_3]$ type complexes are discussed on the basis of the of the calculated magnetic moments.

• Journal of the Korean Society of Marine Environment & Safety
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• v.20 no.4
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• pp.443-450
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• 2014

In this study, we have discussed about the effect of hydrofoil arrangement and longitudinal moment characteristic on longitudinal motion stability of fully-submerged hydrofoil by the experiment of tandem hydrofoil model. First of all, tandem hydrofoil model that has canard wing arrangement has been made and characteristics of lift force and drag force by performing the lift force and drag force measuring experiment has also been estimated. Besides, tandem hydrofoil model's wing arrangement which has the initial stability and self stability of longitudinal motion has also been determined. In longitudinal stability experiment of tandem hydrofoil model, the motion characteristic of pitch and heave and the longitudinal stability of foil borne condition by variation of self stability of longitudinal moment and longitudinal distance are estimated. The result from the experiment and it's important conclusion can be described as below; Increase the self stability for longitudinal moment, the higher self stability for pitch motions in a constant pitch angles. By increasing the self stability for longitudinal moment, the range of fluctuation of pitch motion and heave motion for pitch angle also will change relatively small and longitudinal stability is excellent. Lastly, when the lift force of hydrofoil is remain constants, we can conclude that securing the enough self stability for longitudinal moment is essential for stable foil borne condition of tandem hydrofoil.

• Journal of the Korean Magnetics Society
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• v.18 no.2
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• pp.54-57
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• 2008

Magnetic torquer, which uses torque between magnetic dipole moment and earth magnetic field, has been used to control attitude of satellites. In this work, we developed a magnetic torquer for small scientific satellite and test under environmental conditions of the satellite launching and orbital motion have been carried out. The developed magnetic torquer shows saturation magnetic dipole moment of $15Am^2$, linearity of 0.3 % in the range of ${\pm}12Am^2$, mass of 0.46 kg, and power consumption of 1 Watt at magnetic dipole moment of $10Am^2$.

• Journal of the Korean Magnetics Society
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• v.22 no.5
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• pp.157-161
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• 2012

Magnetism at the interfaces of rocksalt structured half-metals, NaN and CaN were investigated by use of the first-principles band calculations. The electronic structures for the simple interface and mixed interface systems were calculated by the FLAPW (full-potential linearized augmented plane wave) method. From the calculated number of electrons in muffin-tin spheres of each atom, we found, for the simple interface system, that the magnetic moment of the N atom in the CaN (NaN) side is increased (decreased) compared to those of inner N atoms. For the mixed interface system, the magnetic moments of the interface N atoms are similar to the averaged value for the inner N atoms in CaN and NaN side. Among four interface N atoms, the N atom connected to Na atoms in the upper and down layers has the largest magnetic moment and that connected to Ca atoms has the smallest. The number of p electrons in each N atom and the calculated density of states explain well the above situation.

• Journal of the Korean Magnetics Society
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• v.1 no.2
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• pp.1-8
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• 1991

The electronic and magnetic structure of Fe overlayers on W(110) is determined by means of the all-electron local spin density full potential linearized augmented plane wave (FLAPW) method with a single slab approach. Charge and spin densities, magnetic moments, contact hyperfine fields, and layer projected density of states (LDOS) are presented. For bilayer Fe coverage, we find magnetic moments to be 2.90 and 2.30 ${\mu}_B$ for the surface and subsurface Fe layers, respectively, corresponding to a 18% enhancement of the total magnetization compared with the calculated bulk value (2.22${\mu}_B$);For monolayer coverage the moment is 2.56 ${\mu}_B$ which is enhanced by 16% compared to bulk. Unusual changes in the magnetic hyperfine interaction are found in going from a monolayer to a bilayer coverage. Comparison of the results to the theoretical ones of the clean Fe(110) to discuss the hybridization and the negative pressure effects. We discuss our results by comparing them to experimental results.

• Journal of the Korean Chemical Society
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• v.24 no.4
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• pp.269-279
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• 1980

A method for calulation of the magnetic moments for both octahedral and distorted octahedral $[V(III)A_3B_3]$ type complexes, all with $t^2_2$ configuration, has been developed [A and B = O, Cl, N, F or Br]. The calculated magnetic moments by this method are in reasonable agreements with the experimental values. The calculated magnetic moments for distorted octahedral $[V(III)A_3B_3]$/TEX> type complexes decrease as the extent of tetragonal distortion increases.The effects of k (orbital reduction faction factor), $\xi'$/TEX> and temperature on the magnetic moments are also investigated.A new method for calculation of the contribution of $^3T_1$ molecular orbitals to the dipole moment and polarizability has also developed. The calculated contribution of $^3T_1$ molecular orbitals falls in the reasonable range of values.

• Proceedings of the Korean Institute of Intelligent Systems Conference
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• 2002.12a
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• pp.80-83
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• 2002

정밀한 서보기술에 바탕을 두고 있는 산업용 로봇 팔은 기계적인 강성도와 서보기구들로 인하여 정확한 제어가 가능하다 그러나 로봇팔은 동작중비 관성모멘트의 변화와 기하학적인 구조로 인하여 비선형적인 시스템이다. 특히 관성모멘트의 변화는 로봇팔의 회전속도와 로봇팔이 이동시키는 대상물의 무게 등에 따라 관성모멘트는 변할 수 있다. 이로 인하여 관성모멘트의 변화에 따라 로봇팔의 정확한 위치제어가 힘들어진다. 따라서 본 논문에서는 관성모멘트의 변화에도 불구하고 강인한 응답특성을 나타내는 제어기의 설계가 요구된다. 일반적으로 PID .제어기는 설계의 용이성으로 산업현장에서 널리 사용된다. 그러나 PIB 제어기의 각 계수값을 설정하는데 많은 어려움이 발생한다. 따라서 본 논문에서는 PID 제어기의 각 계수 값을 퍼지알고리즘을 이용하여 자동으로 설계할 수 있는 자기동조 PID 제어기를 설계한다.