• 한국군사과학기술학회지
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• 제14권3호
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• pp.359-363
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• 2011

An orthogonal magnetic field is often used for a military vessel in the deperm process such as Flash D deperm protocol and Anhysteretic deperm protocol. The effect of the orthogonal magnetic field on a deperm performance was investigated for a sample with strain-induced magnetization and field-induced magnetization given to different direction. A 70mm wide, 110mm long and 0.25mm thick rectangular steel plate was bent to have U-shape and to generate a strong strain on the bottom region of U-shaped steel plate. Field-induced magnetization was attached by NdFeB permanent magnet. Demagnetization was performed by applying magnetic field with a step decrement from the first field(the first shot) under the action of DC bias field.

• 한국자기학회:학술대회 개요집
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• 한국자기학회 2008년도 Asian Magnetics Conference
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• pp.36.1-36.1
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• 2008

• Journal of Magnetics
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• 제21권1호
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• pp.141-147
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• 2016

Staphylococcus aureus cultures exposed to rotating magnetic field (RMF) were studied in order to analyse the possible induced changes in staphylococcal enterotoxin genes (se) expression. Liquid cultures of S. aureus strains carrying different se were exposed to the RMF of magnetic frequency 50 Hz and magnetic induction 34 mT for 10 h at $37^{\circ}C$. Three time points of bacterial growth cycle were considered for RNA extractions. Gene expression analyses were evaluated using real-time quantitative PCR method. The present study confirmed, that the RMF can stimulate the growth rate of S. aureus cultures in comparison to the unexposed controls, while the stimulation is not strain dependent. The studies have also shown, that the RMF, depending on the exposure time but regardless the bacterial strain, can influence on the expression of various se. In general, except for sea, as a result of bacterial exposure to the RMF through subsequent growth phases, the expression of se decreased, reaching the values below results recorded for unexposed controls. In the case of sea expression remained at a lower level as compared to the control, regardless the time of exposition.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2003년도 춘계학술대회 논문집 센서 박막재료 반도체 세라믹
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• pp.253-256
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• 2003

This study presents the combined effect of electric field application and mechanical compressive stress loading on deformation in a multilayer ceramic actuator, designed with stacking alternatively $0.2(PbMn_{1/3}Nb_{2/3}O_3)-0.8(PbZr_{0.475}Ti_{0.525}O_3)$ ceramics and Ag-Pd electrode. The deformation behaviors were thought to be attributed to relative $180^{\circ}$domain quantities which is determined by pre-loaded stress and electric field. The non-linearity of piezoelectricity and strain are dependent upon the young's modulus resulting from the domain reorientation.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2005년도 하계학술대회 논문집 Vol.6
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• pp.274-275
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• 2005

The tensile strain dependency of critical current in YBCO coated conductors was examined at 77K and in the self magnetic field. A commercially available YBCO sample with Cu stabilizer layer was supplied. There existed a peak in the relation between the Ie and tensile strain, and the reversible variation of $I_c$ with applied tensile strain was found. In the neutral axis Ni alloy RABiTS-$Y_2O_3$/YSZ/$CeO_2$ buffered YBCO tape, the $I_c$ recovered reversibly until the applied strain reached to about 0.5%, representing that a significant residual compressive strain induced during cooling to 77 K influenced the axial strain tolerance of YBCO conductors. To investigate the strain and stress influence on the $I_c$, the stress-strain characteristics of YBCO conductors measured at 77 K were discussed.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2003년도 춘계학술대회 논문집 초전도 자성체 연구회
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• pp.105-107
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• 2003

강자성 형상기억합금은 기존의 압전재료 및 열적 형상기억합금을 이용한 전기-열-기계적 거동의 액츄에이터 재료를 대신할 수 있는 새로운 고성능 액츄에이터 재료로서 각광을 받고 있다. 그러한 강자성 형상기억합금들 중의 한 종류로서 단결정 및 다결정 $Ni_{2}MnGa$ 합금을 이용하여 자장인가시 변형을 관찰하였다. 거대 자장 유기 변형률을 설명하기 위하여 두 모델이 제안되었다. 변태 온도보다 낮은 온도에서는 마르텐사이트 상의 재배열에 의하여 변형이 일어났으며, 그 변태온도보다 높은 온도에서는 상변태에 의한 변형이 일어났다. 미세구조 관찰을 통하여 인가 자장의 방향에 따라 우선적으로 형성되는 마르텐사이트상을 관찰하였다.

• 한국자기학회지
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• 제8권5호
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• pp.261-269
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• 1998

스퍼터링 중 500~600 Oe의 자기장을 인가한 상태에서 제조된 비정징 Sm-Fe 합금 박막에서 6$\times$104 J/m3 크기의 유도자기이방성이 형성되었다. 자장 증착에 이해유도자기이방성이 형성된 합금 박막은 이방성이 형성되지 않은 합금 박막에 비해 자구 구조에 무관한 "포화" 자기변형은 유사하지만, 측정 방향에 따른 자기변형의 이방성 비는 최대 35 정도로서 매우 크게 증가하였다. 이는 자기변형 박막의 디바이스 응용시 성능을 크게 향상시키므로, 실용적인 측면에서 매우 중요하다. 스퍼터링 중 자기장을 인가하지 않고 통상의 마그네트론 스퍼터링에 의해 제조된 비정질 Sm-Fe 합금 박막을 넓은 조성 범위에 걸쳐서 체계적으로 소자한 결과, 이러한 합금 박막에서도 미약하나마 스퍼터링 중의 누설 자계에 의해 증착 도중 유도자기이방성이 형성되는 것을 관찰하였으며, 최대의 유도자기이방성은 Sm 함량 25~30 원자%에서 얻어졌다. 또한 본 합금 박막의 유도자기이방성은 자장 중 열처리에 의해서도 형성되는 것을 관찰하였는데, 형성된 이방성의 크기는 자장 증착에 의해 제조된 시료보다 매우 작게 나타났다. 이는 자장 증착의 경우 원자의 표면 확산을 통한 원자의 이동에 의해 유도자기이방성이 형성되나, 증착 후 자장 열처리에 의한 경우는 체적 확산에 의해 유도자기이방성이 형성되기 때문으로 생각된다.때문으로 생각된다.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2004년도 하계학술대회 논문집 Vol.5 No.2
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• pp.615-618
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• 2004

The piezoelectricity and polarization of multilayer ceramic actuators, being designed to stack ceramic layer and electrode layer alternately, were investigated under a consideration of geometry, the thickness ratio of the ceramic layer to electrode layer The actuators were fabricated by tape-casting of $0.42PbTiO_3-0.38PbZrO_3-0.2Pb(Mn_{1/3}Nb_{2/3})O_3$ followed by laminating, burn-out and co-firing process. The actuators of $5\times5mm^2$ in area were formed in a way that $60{\sim}200{\mu}m$ thick ceramics were stacked 10 times alternately with $5{\mu}m$ thick electrode. Increase in polarization and electric field-displacement with increasing thickness ratio of the ceramic/electrode layer and thickness/cross section ratio were attributed to the change of $non-180^{\circ}/180^{\circ}$ domain ratio which was affected by the interlayer internal stress and Poisson ratio of ceramic layer. The piezoelectricity and actuation behaviors were found to be dependent upon the volume ratio (or thickness ratio) of ceramic layer relative to ceramic layer. Concerning with the existence of internal stress, the field-induced polarization and deformation were described in the multilayer actuator.

• Steel and Composite Structures
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• 제42권6호
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• pp.805-826
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• 2022

The free and live load-forced vibration behaviour of porous functionally graded (PFG) higher order nanobeams in the thermal and magnetic fields is investigated comprehensively through this work in the framework of nonlocal strain gradient theory (NLSGT). The porosity effects on the dynamic behaviour of FG nanobeams is investigated using four different porosity distribution models. These models are exploited; uniform, symmetrical, condensed upward, and condensed downward distributions. The material characteristics gradation in the thickness direction is estimated using the power-law. The magnetic field effect is incorporated using Maxwell's equations. The third order shear deformation beam theory is adopted to incorporate the shear deformation effect. The Hamilton principle is adopted to derive the coupled thermomagnetic dynamic equations of motion of the whole system and the associated boundary conditions. Navier method is used to derive the analytical solution of the governing equations. The developed methodology is verified and compared with the available results in the literature and good agreement is observed. Parametric studies are conducted to show effects of porosity parameter; porosity distribution, temperature rise, magnetic field intensity, material gradation index, non-classical parameters, and the applied moving load velocity on the vibration behavior of nanobeams. It has been showed that all the analyzed conditions have significant effects on the dynamic behavior of the nanobeams. Additionally, it has been observed that the negative effects of moving load, porosity and thermal load on the nanobeam dynamics can be reduced by the effect of the force induced from the directed magnetic field or can be kept within certain desired design limits by controlling the intensity of the magnetic field.

• Journal of Magnetics
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• 제8권1호
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• pp.1-6
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• 2003

The new class of $Gd_5(Si_xGe_{1-x})_4$ compounds undergoes a simultaneous magnetic/structural phase transition giving a high level of strain that can be induced either by change in temperature or by application of a magnetic field. Profound changes of structural, magnetic, and electronic changes occur in the $Gd_5(Si_xGe_{1-x})_4$ system lead to extreme behavior of the material such as the giant magnetocaloric effect, colossal magnetostriction, and giant magnetoresistance. These unique material characters can be utilized for various applications including magnetic solid refrigerants, sensors, and actuators.