• Journal of Magnetics
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• 제20권1호
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• pp.86-90
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• 2015

Electromagnetic actuators are versatile and able to meet demanding requirements, such as operation in very low or very high temperatures. When the actuator is used in a high-temperature environment up to $500^{\circ}C$, we need to know how the force-producing capability of the actuator is affected by the operating temperature. Specifically, it is necessary to know the temperature-dependence of magnetic properties that determine the mechanical forces. In this paper, we measure the changes in magnetic properties of SUS410 material in high-temperature environment. We also devise a novel signal processing technique to remove the integration drift. At the field strength of 18,000 A/m, we found that the flux density at $500^{\circ}C$ is decreased by 26%, compared to the result at room temperature. Therefore, the actuator must be sized appropriately, if it is to operate in high-temperature settings.

• 대한수학회지
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• 제58권6호
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• pp.1529-1547
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• 2021

In this series, we investigate the calculation of mean values of derivatives of Dirichlet L-functions in function fields using the analogue of the approximate functional equation and the Riemann Hypothesis for curves over finite fields. The present paper generalizes the results obtained in the first paper. For µ ≥ 1 an integer, we compute the mean value of the µ-th derivative of quadratic Dirichlet L-functions over the rational function field. We obtain the full polynomial in the asymptotic formulae for these mean values where we can see the arithmetic dependence of the lower order terms that appears in the asymptotic expansion.

• 한국자기공명학회논문지
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• 제25권4호
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• pp.51-57
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• 2021

We study optical quantum transition line widths in relation to magnetic field dependence properties of the electrons confined in an infinite square well potential system between z = 0 and z = L_z in the z - direction. We consider two systems-one is subject to right circularly oscillating external fields and the other is subject to left circularly oscillatory external fields. Our results indicate that the line widths of right circularly oscillating external fields is larger than the line widths of left, while the opposite result is obtained for the line widths.

• Bulletin of the Korean Chemical Society
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• 제16권3호
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• pp.211-214
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• 1995

The catalytic activities of palladium(0,Ⅰ,Ⅱ)-diphosphine complexes were investigated in styrene oxidation using H2O2 as terminal oxidant. The rates showed a dependence on the chelate ring patterns of complexes (PdCl2L); 5-membered ring (L=dppe: 1,2-bis(diphenylphosphino)ethane) < 6-membered ring (L=dppp: 1,3-bis(diphenylphosphino)propane) < 4-membered ring (L= dppm: bis(diphenylphosphino)methane). This sequence correlates with the ligand field strength and interactions between metal and phosphine ligands. Pd(Ⅱ,Ⅰ)-diphosphine complexes which are capable of making 4-membered chelate ring showed an enhancement of catalytic activities for styrene oxidation. The catalytic activities of Pd(0,Ⅰ,Ⅱ)-diphosphine complexes are described in terms of electronic and steric factors.

• 한국해안해양공학회지
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• 제4권3호
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• pp.168-177
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• 1992

해양에서의 조석에너지의 수평적순환에 대한 양상은 반조석주기를 통한 순간플럭스의 궤적인 “에너지 플럭스 타원”의 개염을 적용하여 서술하였다. 이 타원의 특성과 여러 형태의 조석파(평면, Kelvin, Sverdrup, Poincare 및 무조점)체계에서의 에너지플럭스장의 특성이 고려되었다. 적도 또는 위도에 평행한 수노에서의 강제조석파는 여러 수노제원에서의 에너지플럭스 방향에 종속됨을 설명하였다.

• 한국초전도ㆍ저온공학회논문지
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• 제12권2호
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• pp.5-8
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• 2010

In this study, the effect of bending strain on the transport property and critical current of lap and butt-jointed (non-laminated) BSCCO tapes has been investigated. The samples were joined using a mechanically controlled jointing procedure. To achieve a uniform thickness at the joint a single point loading contact has been devised. GFRP mandrels with different bending radii which support the sample during bending have been used. $I_c$ have been measured at 77 K and self field. In the case of easy bending test for jointed BSCCO tapes, sudden degradation of $I_c$ is caused by the local strain concentration due to non uniform deformation at the edge parts of the joint. In the case of hard bending test of jointed BSCCO tapes transverse macroscopic crack at specific subsection caused a large $I_c$ degradation. The transport property of jointed BSCCO tapes in each bending mode was discussed with the damage morphology occurred.

• Journal of Korean Vacuum Science & Technology
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• 제5권2호
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• pp.43-46
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• 2001

Fe-Au alloys are characterized by the complete solubility, and exhibit an fcc-bcc structural transformation at the Fe-rich side. The magneto-optical(equatorial Ken effect : EKE) and optical properties of Fe$\_$1-x/Aux (0 < x < 1) were investigated in the 0.5 - 5.0 eV energy range. The x-ray diffraction study shows the structural fcc-bcc transformation about 80 at. % of Fe. Noticeable changes in the optical properties caused by the fcc-bcc structural transformation was observed. The shape and intensity of the EKE spectra as well as the field dependence of the magneto-optical response were also significantly changed. It is thought that these changes are mainly comes from the induced magnetic moment in Au(and/or the emhanced magnetic moment of Fe). The nature of the prominent structure observed in the UV range of the magneto-optical Ken effect of Au/Fe multilayered films are disscussed in connection with the above results.

• 한국진공학회지
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• 제7권s1호
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• pp.1-6
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• 1998

The influence of the order-disorder structural transition on the magnetic and mageto-optical, and transport properties of Fe-Al and Co-Al alloy films has been investigated. The disordered states in the alloy films were prepared by vapor quenching deposition on glass substrates cooled by liquid nitrogen. The experimental study of the magento-optical properties of the ordered and disordered Fe-Al and Co-Al alloy films has been carried out in 1.05-5.0 eV energy range at room temperature. The transport properties have been measured in 2-300K temperature range with and without magnetic field of 0.5T. The influence of the order-disorder structural transition on the magnetic and magneto-optical properties was discussed by using the effective medium approximation and the structural defect approach. That on the temperature dependence of the resistivity was analyzed in a framework of the partial localization of the electronic states and the variable range hopping conductivity.

• Journal of Magnetics
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• 제11권2호
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• pp.70-73
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• 2006

The magnetization angle and thickness dependence of magnetic anisotropy in the exchange-biased [Pd/Co]${\times}$5/FeMn multilayers with an out-of-plane anisotropy were investigated to determine the origin of perpendicular exchange biasing. As the Co thickness increased to 1.5 nm in the [Pd(0.8 nm)/Co(t)]${\times}$5/FeMn(120 nm) films, the hysteresis loops were converted from square loops at a thin Co (<0.4 nm) to complicated round ones at a thick Co. The irregularly asymmetric step (IAS) at the left top of the loop appeared in the loop of the 0.6-nm Co film due to an inhomogeneity in the exchange anisotropy. As the Pd thickness increased to 1.6 nm, the step disappeared, and the perpendicular magnetic anisotropy was maximized in the Co thickness between 0.6 and 0.9 nm. The conversion of the magnetization loop along the magnetization angle coincided with the equation $H_{(eff)}=H_o\;cos{\theta}$. The IAS of the 0.8-nm Pd film disappeared after thermal annealing up to $200^{\circ}C$ under an external magnetic field.

• 조명전기설비학회논문지
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• 제29권6호
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• pp.49-57
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• 2015

This paper presents the discharge characteristics and economic feasibility of a Dry $Air/O_2$ and a $N_2/O_2$ mixture gas in order to review $SF_6$ alternative. From AC discharge experiment in an quasi-uniform field, it was found that the optimal $N_2/O_2$ mixing ratio which breakdown voltage and surface flashover voltage were the highest was 70/30 and that the pressure dependence on the breakdown voltage was higher than that of the surface flashover voltage in the Dry $Air/O_2$ and the $N_2/O_2$ mixture gas. The mixing ratio (70/30) and the tendency of the pressure dependence were described in detail based on physical factors (impact ionization coefficient, electron attachment coefficient, secondary electron emission coefficient) involved in discharge mechanism and a electron source, respectively. In addition, the performance insulation and the economic feasibility of the Dry $Air/O_2$ and the $N_2/O_2$ mixture gas were discussed so that Dry $Air/O_2$ mixture gaswas more suitable than $N_2/O_2$ mixture gas to the $SF_6$ alternative.