• Title/Summary/Keyword: external magnetic field

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The Analysis of Current Limiting Performance in a High-$T_c$ Superconductor using Flux-Lock Concepts

  • 임성훈;최효상;김영순;이성룡;한병성
    • Progress in Superconductivity
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    • v.3 no.2
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    • pp.229-234
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    • 2002
  • In this paper, we analyzed the fault current performance in a $high-T_{c}$ superconductor(HTS) which was installed on flux-lock reactor with an external magnetic field coil covering the HTS. In this HTS fault current limiter using flux-lock concepts, the initial limiting current level can be controlled by adjusting the inductance of the coils. Furthermore, the current limiting characteristics of $high-T_{c}$ superconducting FCL can be improved by applying the external magnetic field into the $high-T_{c}$ superconductor. This paper discusses current limiting performance according to the inductance of the coil 1 in two cases with ac magnetic field coil or not and suggests the methods to improve the current limiting factor $P_{limit}$, which is defined as the ratio of the limited current $I_{FCL}$ at the current limiting phase to the prospective short -circuit current $I_{PSC}$.TEX> PSC/.

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Orientation and thickness dependence of magnetic levitation force and trapped magnetic field of single grain YBa2Cu3O7-y bulk superconductors

  • Jung, Y.;Go, S.J.;Joo, H.T.;Lee, Y.J.;Park, S.D.;Jun, B.H.;Kim, C.J.
    • Progress in Superconductivity and Cryogenics
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    • v.19 no.1
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    • pp.30-35
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    • 2017
  • The effects of the crystallographic orientation and sample thickness on the magnetic levitation forces (F) and trapped magnetic field (B) of single grain YBCO bulk superconductors were examined. Single grain YBCO samples with a (001), (110) or (100) surface were used as the test samples. The samples used for the force-distance (F-d) measurement were cooled at 77 K without a magnetic field (zero field cooling, ZFC), whereas the samples used for the B measurement were cooled under the external magnetic field of a Nd-B-Fe permanent magnet (field cooling, FC). It was found that F and B of the (001) surface were higher than those of the (110) or (100) surface, which is attributed to the higher critical current density ($J_c$) of the (001) surface. For the (001) samples with t=5-18 mm, the maximum magnetic levitation forces ($F_{max}s$) of the ZFC samples were larger than 40 N. About 80% of the applied magnetic field was trapped in the FC samples. However, the F and B decreased rapidly as t decreased below 5 mm. There exists a critical sample thickness (t=5 mm for the experimental condition of this study) for maintaining the large levitation/trapping properties, which is dependent on the material properties and magnitude of the external magnetic fields.

On Inversion Rations for Push-Pull Paramagnetic Masers (상자성 풋쉬플메이서의 반전화)

  • Cho, Cheol
    • 전기의세계
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    • v.21 no.3
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    • pp.53-56
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    • 1972
  • Electron paramagnetic resonance is one of the concrete forms of magnetic resonance and the superposition of an external magnetic field causes an orientation of the magnetic moment of an atom. On the assumption that both pumped levels be saturated and all relaxation times equal the inversion ratio for a push-pull paramagnetic maser is obtained and compared with those of three-level paramagnetic masers and the magnetic field intensities for 9 and 10 Gc push-pull ruby maser oriented with an angle of 54.deg.44' between the caxis and the magnetic field are, also, obtained.

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DC V-I Characteristics of a High Temperature Superconductor for a 600 kJ Superconducting Magnetic Energy Storage Device in an Oblique External Magnetic Field (경사 외부자장에 대한 600 kJ급 SMES용 HTS도체의 DC V-I 특성)

  • Li, Zhu-Yong;Ma, Yong-Hu;Ryu, Kyung-Woo;Choi, Se-Yong;Kim, Hae-Jong
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
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    • v.21 no.1
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    • pp.79-84
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    • 2008
  • We are developing a small-sized high temperature superconducting magnetic energy storage (HTS-SMES) magnet with the nominal storage capacity of 600 kJ, which provides electric power with high quality to sensitive electric loads. Critical current and N-value of a high temperature superconductor with large current, which was selected for the development of the 600 kJ HTS-SMES magnet, were investigated in various oblique external magnetic fields. Based on the critical current and N-value measured for the short sample conductor, we discussed the DC V - I characteristic of a model coil fabricated with the same conductor of 500 m. The results show that the measured critical current and N-value of the conductor for parallel field are constant in external magnetic fields less than about 0.2 T. However, for oblique fields, its critical current and N -value abruptly decrease in all external magnetic fields. Moreover, the measured critical current of the model coil well agrees with the numerically calculated one based on the DC V - I characteristic measured for the short sample conductor. This suggest that losses and critical currents for an HTS-SMES magnet made up of a high temperature superconductor with anisotropic characteristic are predictable from the data of a short sample conductor.

Magnetic-Shielding Effectiveness Analysis of the Trigger Assembly of Small Arms (소구경 개인화기 격발신호 발생장치의 자기차폐효과 분석)

  • Lee, Kisu;Ahn, Joon Mo;Chae, Je-Wook
    • Journal of the Korea Institute of Military Science and Technology
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    • v.21 no.4
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    • pp.456-463
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    • 2018
  • With the development of weapon systems by mounting various sensors, it makes important to analyze the precise functioning of sensor to external environment. In the case of small arms with magnetic sensor, the malfunction of small arms might be caused by strong external magnetic fields. In this study, the effects of magnetic sensor on external magnetic fields were analyzed, and optimal magnetic shield and shield structure were designed through M&S. In addition, the magnetic-shielding effectiveness of magnetic sensor in small arms was verified with commercial shielding materials. As a result, it was demonstrated that the Fe-Cu-Si-Nd-B with the structure of multi-layer metallic shields was shown the magnetic-shielding effectiveness of 83 % for an external permanent magnet and 19 % for an alternating magnetic field of 180 dBpT at 60 Hz, respectively.

Influences of Magnetic Field on Injection Time of Ferrite Slurry (자기장이 페라이트 슬러리의 주입시간에 미치는 영향)

  • Im, Jong-In;Yook, Young-Jin;Lee, Young-Jin
    • Journal of the Korean Ceramic Society
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    • v.43 no.12 s.295
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    • pp.829-832
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    • 2006
  • In this study, the influence of the magnetic field on ferrite slurry's injection time during the slurry forming process was investigated. The evaluation system of the slurry's injection time under the strong magnetic field was designed with FEM and manufactured. Studied parameters were the applied magnetic field, the input pressure of the slurry, and the supplying tube materials. As the results, the injection time was increased with the external magnetic field strength and rapidly decreased with increasing the input pressure of the slurry. Also the injection time was decreased when the supplying tube was manufactured with the magnetic material having the higher magnetic permeability than the ferrite.

Selective detection of AC transport current distributions in GdBCO coated conductors using low temperature scanning Hall probe microscopy

  • Kim, Chan;Kim, Mu Young;Park, Hee Yeon;Ri, Hyeong-Ceoul
    • Progress in Superconductivity and Cryogenics
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    • v.19 no.1
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    • pp.26-29
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    • 2017
  • We studied the distribution of the current density and its magnetic-field dependence in GdBCO coated conductors with AC bias currents using low temperature scanning Hall probe microscopy. We selectively measured magnetic field profiles from AC signal obtained by Lock-in technique and calculated current distributions by inversion calculation. In order to confirm the AC measurement results, we applied DC current corresponding to RMS value of AC current and compared distribution of AC and DC transport current. We carried out the same measurements at various external DC magnetic fields, and investigated field dependence of AC current distribution. We notice that the AC current distribution unaffected by external magnetic fields and preserved their own path on the contrary to DC current.

A Study on the Microwave Reflection of Plasma in a Magnetic Field (방전프라즈마내 자계에 의한 마이크로파 반사특성)

  • 김봉열;김정기
    • Journal of the Korean Institute of Telematics and Electronics
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    • v.6 no.1
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    • pp.12-18
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    • 1969
  • The characteristics of microwave reflection in the media of cold gaseous plasma is analysed to various external magnetic flux density. The DC discharge plasma is generated in the rectangular waveguide which contains two electrodes and helium gas at the pressure of 10-2mm Hg. The reflected and transmitted power of microwave is measured when the electric field is parallel to, and perpendicular to the external magnetic field. It shows that the reflected power is increased as the magnetic flux density is increased in the parallel case, but the maximum value of the reflected power is occured at the cyclotron resonance (3120 Gauss) in the perpendicular case.

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A Study on the Rheology Characteristics of Magnetic Fluids in a Circular Pipe (원관내 자성유체의 Rheology 특성에 관한 연구)

  • Jeon, Eon-Chan;Park, Joung-Woo;Kim, Tae-Ho;Kim, Soo-Yong
    • Journal of the Korean Society of Manufacturing Process Engineers
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    • v.7 no.2
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    • pp.38-44
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    • 2008
  • In the present paper, we theoretically analyze the flow of magnetic fluids in a circular pipe with a vertical magnetic field and investigate the magnetic response by the external magnetic field. Theoretical study through the governing equation derived by Siliomis is carried out with numerical analysis by the Gauss Elimination Method. Using polar and magnetic effect parameters, theoretical equations and distributions for the velocity, apparent viscosity as the magnetic response are shown. Especially, in the region of strong magnetic field the specific property is appeared by finding a critical magnetic effect parameter for a polar effect parameter.

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Magnetization Loss Characteristics at Arbitrary Directional Magnetic Field by Perpendicular Magnetization Loss in YBCO CC and BSCCO Stacked Conductors (YBCO CC 적층 및 BSCCO tape 적층선재에서 수직자화 손실 값을 이용한 임의 방향 자화손실 평가)

  • Lee, Ji-Kwang;Lim, Hyoung-Woo;Park, Myung-Jin;Cha, Guee-Soo
    • The Transactions of The Korean Institute of Electrical Engineers
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    • v.56 no.2
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    • pp.282-288
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    • 2007
  • Magnetization loss of high temperature superconductoring BSCCO tape and YBCO coated conductor(YBCOCC) is most important issue in the development of superconducting power devices. In this paper, the measured results of magnetization losses under various angles of external magnetic field in BSCCO tape stacked conductors and YBCO CC stacked conductors are presented and compared with each other. Also, we present the compared results of magnetization losses measured at arbitrary reaction magnetic fields and analyzed with perpendicular magnetic field components of those. The results show that magnetization losses of YBCO CC single and stacked conductors agree well with the analyzed value by it's perpendicular magnetic field component, but BSCCO single and stacked conductors are not.