• Journal of the Korean institute of surface engineering
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• v.31 no.3
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• pp.151-156
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• 1998

코발트계 비정질 합금을 여러 온도 구간 및 시간에 대해서 열처리하며 표면 결정화 현상이 자기 이방성에 미치는 영향을 탐구하였다. 자기 이방성은 비정질 표면의 결정 구조에 민감한 변화를 보였는데 면심입방점 코발트에 많은 결함이 존재할 경우 자기이방성이 최대치를 나타내였다.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.22 no.4
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• pp.178-182
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• 2012

The grain growth is very important because of its great influence on the various materials properties. Therefore, in this study, the effects of anisotropic grain boundary energy on grain growth in 2-D have been investigated with a large scale phase field simulation model on PC. A $2000{\times}2000$ grid system and the initial number of grains of about 73,000 were used in the computer simulation. The anisotropic ratio of grain boundary energy, ${\sigma}_{max}/{\sigma}_{min}$, has been varied from 1 to 3. As the anisotropy increased, the grain growth exponent, n, increased from 2.05 to 2.37. The grain size distribution showed a central plateau in the isotropic case, and was changed into no central plateau and the increasing population of very small grains in the anisotropic case, resulting from slowly disappearing grains. Finally, simulated microstructures were compared according to anisotropy.

• Tunnel and Underground Space
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• v.11 no.1
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• pp.59-63
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• 2001

The total number of elastic constants of an anisotropic body is 9 and thus it is very difficult to measure these constants experimentally. The number of elastic constants can be reduced if a rock or rock mass is regarded as isotropic or transversely isotropic material. Since only 4 stress-strain relationships can be obtained, it is theoretically impossible to determine all 5 constants from a single uniaxial compression teat. Lekhnitskii overcame this problem by suggesting the fifth equation based on laboratory tests. But his equation is theoretically wrong and does not agree with experimental results. This paper describes the stress-strain relationships and the independent/dependent elastic constants of an anisotropic mass and suggests a testing mothed to determine 5 independent elastic constants for a transversely isotropic rock.

• Journal of the Korean Magnetics Society
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• v.15 no.1
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• pp.25-29
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• 2005

Magnetic properties of YIG films grown by solid phase epitaxy (SPE) was measured as a function of temperature with focus on magneto-crystalline and perpendicular magnetic anisotropy. Perpendicular magnetic anisotropy was not induced in the SPE YIG films annealed at low temperature by relaxing residual stress through formation of dislocation. On the contrary the films annealed at high temperature showed perpendicular magnetic anisotropy which shows very low density of dislocation. Perpendicular magnetic anisotropy field decreased linearly up to a high temperature of $230^{\circ}C$ above which magneto-crystalline anisotropy disappeared. Coercivity also decreased linearly with temperature up 세 $230^{\circ}C$. Magneto-crystalline anisotropy of perpendicular anisotropy induced epitaxial (111) YIG films can be measured using $H_k=4K_1/3M_s$. Temperature behavior of initial susceptibility can be successfully explained by Hopkinson effects. Curie temperature of YIG films grown on GGG substrate with high paramagnetic susceptibility can be easily measured using the results.

• 기계와재료
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• v.23 no.3
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• pp.82-95
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• 2011

다결정압연판재는 열가공공정을 거쳐서 생산되므로 공정의 특성을 반영하는 미세조직/집합조직 특성을 가지게 된다. 결정립들은 특정방향으로 배향하고 결정립의 형상과 크기도 변화한다. 이러한 변화는 거시적으로 다결정판재의 이방성으로 귀결이 되는데, 근본적으로 판재를 구성하는 단결정들의 기계적 물성이 각각의 방향별로 이방성을 띄기 때문이다. 본 자료에서는 압연공정시 다결정판재의 수직/평면이방성의 발생원인을 집합조직과 결정소성학을 이용하여 제시하고자 하였다.

• The Journal of Engineering Geology
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• v.3 no.3
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• pp.231-239
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• 1993

This paper presents a result on the determination of velocity distribution by a tomographic inversion of crosshole seismic traveltimes in transversely isotropic(aniso tropic) media. The crosshole traveltimes used in this study are synthetic ones computed by ray tracing for some models having isotropic and transversely isotropic velocity distributions. The traveltimes are inverted by a general ART and ansotropic ART which considers the transversely isotropic effect during inver sion. The aniotropic ART gives accurate velodty distributions of transversely isotropic and isotropic models, while the isotropic ART determines accurate velocities only for the isotropic model but inaccurate for the transversely isotropic one. Therefore, the anisotropic ART may be used in case where no information is known on the isotropy or transverse isotropy of a survey area.

• Composites Research
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• v.17 no.2
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• pp.9-14
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• 2004

In this study, analytical investigations on the flexural behavior of FRP reinforced concrete slab were discussed. In the derivation of analytic solution, the FRP reinforced concrete slab was modeled as a structural orthotropic plate. To determine the flexural rigidities of an orthotropic plate model, the elastic equivalence method was employed. In the finite element analysis, the approximate method to determine the rigidity matrix of orthotropic plate element was also suggested using the elastic equivalence method. The results obtained by the analytical solution and the finite element analysis were compared with that of experiment.

• Journal of the Korean Magnetics Society
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• v.21 no.1
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• pp.10-14
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• 2011

We have measured the ferromagnetic resonance (FMR) signal in as deposited and $400^{\circ}C$ annealed CoFeB/MgO thin film to investigate the annealing effect on magnetic anisotropies and FMR linewidth (${\Delta}H_{PP}$). The uniaxial anisotropy field ($H_{K1}$) was only observed in the as deposited sample. Whereas, in the $400^{\circ}C$ annealed sample, the biaxial anisotropy field ($H_{K2}$) was additionally observed in accompany with uniaxial anisotropy field ($H_{K1}$). The appearance of biaxial anisotropy fields was originated from the crystalline growth of bcc CoFeB(001) from the MgO(001) interface and by the B diffusion during thermal annealing. Also, the ${\Delta}H_{PP}$ of $400^{\circ}C$ annealed sample was increased compared with that of as deposited sample, which was due to the broad distribution of the magnetization axis by the biaxial anisotropy.

• Journal of the Korean Magnetics Society
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• v.8 no.3
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• pp.144-149
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• 1998

A new method to calculate the spin reorientation angle of cone anisotropy from magnetization curves of magnetically aligned powder is suggested. The spin reorientation angle of polycrystalline $Nd_2Fe_{14}B$ determined by this method coincided with the results obtained from torque magnetometry or magnetization measurements on single crystal. The underestimation of about 9% is expected if the basal plane anisotropy is neglected in determination of the spin reorientation angle of $Nd_2Fe_{14}B$ at 4.2 K.

• Journal of the Korean Magnetics Society
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• v.9 no.4
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• pp.173-176
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• 1999

Errors of saturation magnetization and magnetocrystalline anisotropy constant determined by magnetization curve of magnetically aligned unixial power were analyzed. In case of alignment factor ${\Theta}_0=10{\circ}$, magnetic constant errors of $Nd_2Fe_{14}B$ were calculated to be error of $M_S{\risingdotseq}1{\%}\;and\;error\;of\;K_1{\risingdotseq}13\;{\%}$, respectively, and magnetic constant errors of Ba-ferrite were calculated to be error of $M_S{\risingdotseq}1{\%}\;and\;error\;of\;K_1{\risingdotseq}17\;{\%}$. In this method, $M_s$ was found to be determined with high accuracy. High alignment is desirable for high accuracy.