• Journal of Digital Convergence
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• 제8권4호
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• pp.165-176
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• 2010

The aim of this study is to determine the relationship between variables affecting learning effect and flow experience on an e-Learning English program. There are 4 independent variables; English thinking structure, self-efficacy in English and flow. The results are as follows: Firstly, there is statistically significant positive correlation between each variable of English thinking structure, pre English skill, self-efficacy in English, flow and learning effect. Secondly, it appeared that flow was affected by all three variables of English thinking structure, pre-English skill and self-efficacy in English. Also flow experience affected learning improvement. Finally, it is verified that there is a mediating effect of flow experience on the relation of self-efficacy in English and learning effect.

• Journal of the Korean Magnetics Society
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• 제20권2호
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• pp.75-82
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• 2010

A recent progress on the prediction of the thermal stability of a nanostructured exchange-coupled trilayer is reviewed. An analytical/numerical combined method is used to calculate its magnetic energy barrier and hence the thermal stability parameter. An important feature of the method is the use of an analytical equation for the total energy that contains the magnetostatic fields. Under an assumption of the single domain state, the effective values of all the magnetostatic fields can be obtained by averaging their nonuniform values over the entire magnetic volume. In an equilibrium state, however, it is not easy to calculate the magnetostatic fields at the saddle point due to the absence of suitable methods of the accessing its magnetic configuration. This difficulty is overcome with the use of equations that link the magnetostatic fields at the saddle point and critical fields. Since the critical fields can readily be obtained by micromagnetic simulation, the present method should provide accurate results for the thermal stability of a nanostructured exchange-coupled trilayer.

• Journal of the Computational Structural Engineering Institute of Korea
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• 제15권4호
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• pp.727-739
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• 2002

Based on a generalized variational principle for magneto-thermo-elasticity, a theoretical model is proposed to describe the coupled magneto-thermo-elastic interaction in soft ferromagnetic plates. Using the linearized theory of magneto-elasticity and perturbation technique, we analyze the magneto-elastic and magneto-thermo-elastic instability of simply supported ferromagnetic plates subjected to thermal and magnetic fields. A nonlinear finite element procedure is developed next to simulate the magneto-thermo-elastic behavior of a finite-size ferromagnetic plates. The effects of thermal and magnetic fields on the magneto-thermo-elastic bending and buckling is investigated in some detail.

• Journal of Digital Convergence
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• 제12권10호
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• pp.515-523
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• 2014

The purpose of this study was to identify the structural relationship model between teacher attachment, peer attachment, self-encouragement, career self-efficacy, and career maturity and to analyze the direct or indirect effect among latent variables. 220 elementary school students in a Cheongju were sampled. Four measurement instruments were employed; the Teacher Attachment Peer Attachment Scale, Self-encouragement Scale, the Career self-efficacy and the Career Maturity scale. The Collected data were analyzed by correlation and regression alalysis with SPSS program and Structural Equation major Modeling(SEM) and fitness of the final model were CFI=.957, TLI=.951, RMSEA=.049. The results of this study were as follows: First, there were significant positive correlations among teacher attachment, peer attachment, self-encouragement, career self-efficacy, and career maturity. Second, according to the structural equation modeling, the results showed that self-encouragement and career self-efficacy mediated the effect of teacher attachment, peer attachment on career maturity.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• 제21권6호
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• pp.610-616
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• 2010

In this paper, particle swarm optimization(PSO) is applied for the design of frequency selective surface based artificial magnetic conductor. An equivalent circuit model for this artificial magnetic conductor(AMC) with Jerusalem Cross arrays was derived and then PSO was applied for obtaining the optimized geometrical parameters with desired resonant frequency. The resonant frequency and the reflection phase characteristics from the optimization were compared to the results from commercial software for verifying the validity of this paper. The procedure presented in this paper can be applied to design the AMC with different frequency selective surface and also can be used for the design of microwave circuits like the AMC ground planes.

• Journal of the Computational Structural Engineering Institute of Korea
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• 제29권2호
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• pp.193-199
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• 2016

Since the variations of electromagnetic suspension forces of maglev trains have close relations with the acceleration of the levitated bodies, it is basic to control the levitation forces using the measured acceleration of vehicles. In this study, an airgap control algorithm based on acceleration feedback is applied to maglev trains and a dynamic analysis method is developed considering maglev train-guideway interaction. Using the developed method, dynamic behaviors of a maglev train-guideway interaction system are investigated. It is observed from the analysis that the current design guidelines can be satisfied when the proposed airgap control algorithm is employed. Using the contorl algorithm, the current guidelines can be improved and economical maglev railway guideway structures can be designed.

• Journal of the Korean Magnetics Society
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• 제8권3호
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• pp.131-137
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• 1998

The thickness dependence of the microstructure and the giant magnetoresistance behavior of co-evaporated Co-Ag granular alloy films were investigated. The maximum magnetoresistance ratio of 24% was observed in the the as-deposited state of the 40 at. % Co alloy having 200 nm thickness. The surface scattering contributed about 20% to the total resistivity in the 20 nm thick films. The MR ratio dropped sharply when the film thickness was below 50 nm. The reduction in the Co particle size and the increase in solid solubility of Ag in fcc Co when the film thickness decreased were observed using a high resolution TEM. The aspect ratio of the Co particles was also affected by the film thickness. Those microstructural changes as well as the surface induced spin flipping play a significant role in the $\Delta$p change.

• Proceedings of the Korean Magnestics Society Conference
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• 한국자기학회 2006년도 동계학술연구발표회 및 자성 스핀트로닉스 국제학술대회
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• pp.107-107
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• 2006

• Proceedings of the Korean Magnestics Society Conference
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• 한국자기학회 2014년도 임시총회 및 하계학술연구발표회
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• pp.15-16
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• 2014

• Proceedings of the Korean Magnestics Society Conference
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• 한국자기학회 2002년도 동계연구발표회 논문개요집
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• pp.52-53
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• 2002

스핀밸브 구조는 현재 고기록밀도 자기저장 분야에서 그 응용범위가 넓다. 이런 고기록밀도를 달성하기 위해서는 자기저항곡선의 비대칭성 문제가 중요하다. 그러므로 비대칭성 문제를 해결하여 센서의 민감도를 높이기 위해서는 고정층에서 나오는 정자기장을 제어하는 것이 필요하다. 이런 문제를 해결하기 위해 IBM에서 최초로 합성형 스핀밸브 구조가 도입하였다 [1]. 이런 합성형 스핀밸브는 기존의 스핀밸브에 비해 열적으로나 또는 자기적으로 매우 안정한 장점을 가지고 있다. (중략)