• Journal of the Korean Magnetics Society
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• v.23 no.5
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• pp.154-158
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• 2013

We have analyzed the magnetization curves measures by using VSM and MOKE in synthetic antiferromagnetic coupled CoB/Ru/CoB thin film. The measured results were compared with calculated ones by Stoner-Wohlfarth model based on the magnetization behavior of two ferromagnetic layers ($M_1$, $M_2$). The calculated total magnetization ($M_{tot}=M_1+M_2$) and single layer magnetization($M_1$) behaviors were compared with measured results by using VSM and MOKE, respectively. The total magnetization curve ($M_{tot}=M_1+M_2$) showed reversible magnetization behavior with flopping field of about 50 Oe. While single layer magnetization ($M_1$) behaviors showed irreversible magnetization behavior in the field range of $H_F$ < H < $H_F$. These magnetization behaviors were explained by the angle difference between magnetization directions of two ferromagnetic layers in SAF sample.

• Journal of the Korean Magnetics Society
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• v.2 no.2
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• pp.140-144
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• 1992

Magnetization of permanent magnet in the strong magnetic field is changeable. So the change of magnetization must be considered for the accurate analysis of the system with permanent magnets. But the hysteresis characteristice of permanent magnet cannot be represented in simple mathematical form. In this paper, Preisach model combined with finite element method which can describe the hysteresis phenomena is applied to analyze the permanent magnet system. To validate the method, it is applied to the force calculations between two magnets with different coercivities and the numerical results are compared with measured data.

• Proceedings of the KIEE Conference
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• summer
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• pp.968-970
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• 2004

자성체의 자화 특성을 해석하기 위해서는 자성체가 가지고 있는 포화 현상과 Hysteresis 현상을 고려해 주어야 한다. 하지만 현재 자화 특성 해석에서는 Hysteresis 현상을 무시하고 포화 현상만을 고려한 해석을 진행하거나 Hysteresis의 메이저 루프 특성만을 고려한 비선형 문제 해석만을 사용하고 있다. 하지만 자성체의 Hysteresis 특성은 메이저 루프적 특성 뿐만이 아닌 마이너 루프적인 특성을 가지고 있어 이 두 특성에 따라 많은 자화량적 변화를 가지게 된다. 또한 같은 재료적 특성을 가진 자성체라고 해도 그 형상에 따라 다른 자화 특성 분포를 가지고 있다. 이러한 두가지 특성을 전부 고려한 해석이 되어야 만이 정확한 자화 특성 해석 방법이라고 할 수 있다. 본 논문에서는 이와 같은 멀티브렌치적 특성과 자성체 형상에 따른 특성을 해석하기 위하여 Preisach 모델링을 이용하여 자성체의 형상에 따른 자화적 특성을 해석하는 연구를 진행하였다.

• Proceedings of the KIEE Conference
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• 2015.07a
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• pp.890-891
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• 2015

본 논문에서는 속도 제어를 위한 가변자속 메모리 모터(Variable Flux Memory Motor)의 특성과 감자전류 산정에 대하여 다루었다. 서론에서는 VFMM에 대한 특징 및 설계를 위한 분석 방안을 제시하였으며, 메모리모터의 동작 원리와, 정밀한 해석 방법은 본론을 통하여 자세히 다루었다. 감자전류는 프라이자흐 모델을 이용하여 초기 자석의 자화량을 비선형 적으로 구한 후 인가된 d축 전류에 따른 변화된 자화량 및 기전력 값들을 반복적인 연산을 통하여 신뢰성 있는 감자전류를 산정하였다.

• Journal of the Korean Magnetics Society
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• v.2 no.2
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• pp.145-149
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• 1992

The characteristics of electromagnetic devices with permanent magnet depends greatly on the remanence pattern of permanent magnet. So, it is necessary to analyze the pattern of remanence in permanent magnet. This paper presents a finite element analysis of magnetizer considering the nonlinearity and anisotropy of yoke and magnet in magnetizer. The distributions of magnetizations are obtained according to the variations of magnetizing currents for two kinds of magnetizers with different magnetizing poles. It is found that the excessive magnetizing current results in the reduction and polarity reversion of magnetization in the multi-pole magnetizing system where the pole angle is too small. During the design and analyzing of multi-pole magnetizer, it must be considered that there exists an optimal value of magnetizing current and pole angle of magnetizer.

• Proceedings of the Korean Nuclear Society Conference
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• 1996.05c
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• pp.317-322
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• 1996

원자로 압력공기 재료인 SA508-3 강의 중성자 조사량에 따른 Hysteresis Loop 의 변화와 Barkhausen Noise 의 변화를 조사하였다. 조사량에 따른 최대자기유도, 보자력, 잔류자화 및 Barkhausen Amplitude 의 변화를 측정하였으며, 이를 격자변형에 의한 자구 벽의 pinning 과 중성자 조사에 의한 자기에너지의 변화로 설명하였다. 중성자 조사에의 한 자기적 성질은 기계적 성질의 변화보다 훨씬 민감하게 변화하였으며, 보자력과 잔류자화는 중성자 조사량에 따라 선형으로 증가하였다. 이를 이용하면 조사손상 평가와 함께 조사량을 측정하는 dosimetry 에도 적용될 수 있는 가능성이 있다.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.4 no.1
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• pp.9-16
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• 2011

In this paper, we propose an efficience transcoder architecture to support a simutaneous multibitrate output. First, we discuss about some architectures to realize this feature. Next, we explain the proposed architecture, it shares not only VLD-IQ but alse Q-VlD which have the same quantization step sizes each other. We anlyze the numbers of Q-VLC times per on Macroblock to the investigate an effect of sharing, and evaluate its computation complexity. The result of simulation, that complexity has an upper limit and it cn support any numbers of bitstream by about 3~6 times complexity than single output.

• Journal of Korean Society of Forest Science
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• v.79 no.3
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• pp.290-301
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• 1990

The 167 plus tree clones of Pinus koraiensis in clone bank planted in 1983 were investigated for time of flowering, rate of flowering, and number of flowering from 1986 to 1989. The results were as follows : 1) There were clones in the minority which do not cross in natural pollination between earlest flowering female clones and latest shedding male clones. 2) The rate of male flowering appeared less than rate of female flowering and received influence of genetic more than rate of female flowering. 3) The numbers of flowering in female and male flower were affected by small number of clones. 4) The flowering number for female strobili was not related to the flowering number of male flower. The 42 clones among 167 clone had not male flower. 5) The flowering number of 167clones were classified three groups in female flower and four groups in male flower by L.S.D 5% test. 6) The clones with abundant female and male flower were selected based on the component analysis. 7) As Based on flowering rate and number of female, the juvenile phase of plus tree clones appeared to be until four years after grafting ; the transition period appeared to be from five to seven years after grafting ; the adult phase appeared to begin from eight years after grafting, 8) The grafted trees of Pinus koraiensis appeared early flowerring about six years compared with seedling trees.

• Applied Chemistry for Engineering
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• v.25 no.2
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• pp.227-232
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• 2014

Depolymerization of sodium alginate (SA) was carried out by electron beam irradiation in a hydrogen peroxide atmosphere. E-beam with 1.0 and 2.5 MeV of accelerating voltages were employed in this experiment. For control of molecular weight and the radiation yield of scission ($G_s$), the irradiation dosage of e-beam was managed in a range from 2.5 to 20 kGy while the quantity of hydrogen peroxide was adjusted in a range of 0 to 4.5%. The chemical structure of the depolymerized sodium alginate (DSA) was analyzed to have scission of 1,4-glycoside bond mainly and a few fragmentary formate end groups which may be produced by the cleavage between C2 and C3 in repeating unit of alginate. It turned out to have simple chemical structures at the DSA end groups, produced by e-beam irradiation, similar with those in the polymer SA structure. As a result, the molecular weight of SA decreased as the energy and dosage of applied e-beam increased, and the radiation yield of scission showed the best result at 2w/v% in SA concentration. The highest radiation yield of scission ($7.919{\times}10^4mol/J$) was confirmed when an irradiation dosage of 20 kGy (2 MeV) and 1.5% hydrogen peroxide were used in 2% SA aqueous solution.

• Journal of the Korean Magnetics Society
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• v.10 no.2
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• pp.86-92
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• 2000

The spin wave absorption spectra are obtained by a simultaneous solution of the Maxwell equation and the Gilbert equation considering the boundary condition of electromagnetic wave and magnetization in the film surfaces. The physical parameters that influence the absorption energy are thickness, exchange stiffness constant, surface magnetic anisotropy, magnetization. damping factor, electric resistivity of the thin film. We investigated how these parameters affect the resonance field, the linewidth and the intensity of the spin wave spectrum.