권호 표지

Progress in Superconductivity and Cryogenics (한국초전도ㆍ저온공학회논문지)

The Korean Society of Superconductivity and Cryogenics (KSSC)

  • Quarterly
  • /
  • 1229-3008(pISSN)
  • /
  • 2287-6251(eISSN)

Domain

  • Physics ＞ Condensed Matter Physics

Aim & Scope

Progress in Superconductivity and Cryogenics is the official publication of The Korea Institute of Applied Superconductivity and Cryogenics and the Korean Superconductivity Society. It was launched in 1999, and accepts original research articles and review papers on research on superconductivity and related fields of physics, electronic devices, materials science, large-scale applications for magnets, power and energy, and cryogenics. The Journal is published quarterly in March, June, September, and December each year. Supplemental issues are published occasionally. The official title of the journal is 'Progress in Superconductivity and Cryogenics' and the abbreviated title is 'Prog. Supercond. Cryog.' All submitted manuscripts are peer-reviewed by two reviewers. The text must be written in English. All the articles in this journal are KCI and SCOPUS as of 2015. The URL address of the journal is http://psac.kisac.org where full text is available. This work was supported by the Korean Federation of Science and Technology Societies grant funded by the Korea government.

http://psac.kisac.org/ KSCI KCI SCOPUS

Volume 9 Issue 3

  1. Yoo, Jae-Un;Lee, Sang-Moo;Jung, Ye-Hyun;Lee, Jae-Young;Youm, Do-Jun 1
    https://doi.org/10.9714/psac.2007.9.3.001 PDF KSCI
    The current profiles in a coated conductor with transport current were calculated using an iterative inversion method from the data of the magnetic flux density profiles measured. The applied current was increased from 0 to 60 A by 10A step and decreased down to -60A by 20A step. The magnetic flux profiles were measured at a distance of 400 mm above the surface of the coated conductor using a scanning hall probe method. The current profiles calculated were very different from the Bean model: current density profile is not a constant in the critical region. However the aspect of the change of the current and magnetic flux density profiles in the case of decreasing applied current are similar to the theoretical calculations in Brandt's paper.
  2. Chung, Kook-Chae;Yoo, Jai-Moo;Kim, Young-Kuk;Wang, X.L.;Dou, S.X. 5
    https://doi.org/10.9714/psac.2007.9.3.005 PDF KSCI
    All three buffer layers of $Y_2O_3$, YSZ, and $CeO_2$ have been deposited on the biaxially textured metal substrates using rf-sputtering method, The first 50-70nm thick $Y_2O_3$ films were grown epitaxially on biaxially textured metal substrates as a seed layer and followed by the diffusion barrier ${\sim}100nm$ thick YSZ and subsequent capping layer ${\sim}200nm$ thick $CeO_2$ deposited epitaxially on top of $Y_2O_3$ seed layer. The epitaxial orientation of all three layers were all (100) grown with rocking curve Full Width at Half Maximum(FWHM) of $4-5^{\circ}$ and in plane phi-scan FWHM of $6-8^{\circ}$ using X -ray diffraction analysis. The NiO phases formed during the $Y_2O_3$ seed layer deposition seem to degrade the crystallinity and roughen the surface morphology of the following layer observed by AFM(Atomic Force Microscopy). The buffered tapes were used as substrates for long length YBCO coated conductors with high critical current density $J_c$. The five multi-turn of metal tapes was employed to increase the thickness of films and production rate to compensate the low growth rate of rf-sputtering method.
  3. Kim, Tae-Hyung;Oh, Sang-Soo;Kim, Ho-Sup;Ko, Rock-Kil;Song, Kyu-Jeong;Ha, Hong-Soo;Lee, Nam-Jin;Park, Kyung-Chae;Ha, Dong-Woo 9
    https://doi.org/10.9714/psac.2007.9.3.009 PDF KSCI
    In this study. we searched for the mechanical and electrical properties of laminated coated conductors with stabilizer tape. Stabilizer tape plays a role for mechanical and electrical stability and environmental protection. Cu material stabilizer was laminated to Ag capping layer on SmBCO conductor layer. This architecture allows the wire to meet operational requirements including the stressless at cryogenic temperature and winding tension as well as mechanical bending requirements including thermal and electrical stability under fault current conditions. First, we have experimentally studied mechanical bonding properties of the laminated Cu stabilizers on SmBCO coated conductors. We have laminated SmBCO coated conductors by continuous dipping soldering process, Second, we have investigated electrical properties of the SmBCO coated conductors with stabilizer lamination. We evaluated bonding properties, peeling strength and critical current for laminated SmBCO coated conductors with Cu stabilizers.
  4. Yoo, Jae-Un;Lee, Jae-Young;Jung, Ye-Hyun;Lee, Sang-Moo;Youm, Do-Jun 13
    https://doi.org/10.9714/psac.2007.9.3.013 PDF KSCI
    We employed home-made position marking module in the scanning Hall probe system. The module is composed of two coils of which gap, a, between wires in a coil is $500{\mu}m$. We appiled 10-35mA of current with 15Hz in the coils and recorded ac corresponding magnetic field signal with respect to measuring time while we measured DC field profiles produced due to superconducting film in a perpendicular magnetic field. We calibrate the position, x, of coils using the measuring time and location of the coils in the holder. The error range was about ${\pm}0.1mm$. We test the module as we applied current of 100A and filed of 1kG in the superconducting tape. It was confirmed that there was no interference between superconducting tape and marking coils.
  5. Lee, Seung-Ryul;Kim, Jong-Yul;Yoon, Jae-Young;Lee, Byong-Jun 16
    https://doi.org/10.9714/psac.2007.9.3.016 PDF KSCI
    This paper describes protection system of new distribution power system with superconducting power devices such as HTS cable, HTS transformer, HTS-FCL. First of all, this paper investigates protection systems of Korean power system and then do a basic study on relaying systems in the power system with HTS power devices. For the more detailed results, we did the study using EMTDC relaying system modeling from the viewpoint of superconducting power devices application. Then we proposed some solution for a high resistance fault problem.
  6. Park, Dong-Keun;Bang, Joo-Seok;Yang, Seong-Eun;Ahn, Min-Cheol;Sim, Ki-Deok;Yoon, Yong-Soo;Nam, Kwan-Woo;Seok, Bok-Yeol;Ko, Tae-Kuk 21
    https://doi.org/10.9714/psac.2007.9.3.021 PDF KSCI
    Superconducting fault current limiter (SFCL) is attractive apparatus to reduce fault current in power grid. Since it is applied to the alternating current (AC) power line, the SFCL has losses in the normal operation. Recently, coated conductor (CC) is noticeable material employed for resistive bifilar winding type SFCL in many research groups. Bifilar structure is expected to have low AC loss by magnetic field offset as compared with the single tape structure in the same length. This paper reports about characteristic of bifilar pancake type coil for SFCL application in AC loss aspect. The bifilar coil is wound using CC with facing on HTS sides each other. Transport AC loss measurement and characteristic analysis of the bifilar coil using CC have been performed at 77K. The test results are compared with the Norris equations and the test results of non-inductively wound paralleled solenoid type coil which is suggested and tested in this group at present.
  7. Ahn, Min-Cheol;Seok, Bok-Yeol;Ko, Tae-Kuk 26
    https://doi.org/10.9714/psac.2007.9.3.026 PDF KSCI
    In recent years. YBCO coated conductor (CC) called as second generation HTS (high temperature superconducting) wire has been developed as a suitable material for resistive superconducting fault current limiter (SFCL). For designing the SFCL. the required length of superconducting wire is inverse proportional to the maximum temperature reached when a fault occurs. Since the required length strongly affects a manufacturing cost, it is the most important parameter to determine the maximum temperature reached. It is necessary to observe the repetitive over-current characteristics of HTS wire. This paper attempts to measure the variation of critical current of YBCO CC after repetitive over-current pulse. No degradation of the critical current of CC sample was observed by applying 100 times over-current pulse which makes temperature above 400 K after 100ms. This study can be useful in designing optimally resistive SFCL employing YBCO CC. The maximum permissible temperature can be set to 400K. so wire length could be reduced by 30% compared in case of 300K-criterion.
  8. Baik, S.K.;Kwon, Y.K.;Lee, E.Y.;Lee, J.D.;Kim, Y.C.;Moon, T.S.;Park, H.J.;Kwon, W.S. 32
    https://doi.org/10.9714/psac.2007.9.3.032 PDF KSCI
    On the contrary of a conventional motor with very narrow air-gap. it is difficult to calculate the accurate magnetic field distribution and the performance of an air-cored superconducting motor by 2 dimensional analysis. which does not use high permeability material except outer machine shield. This paper aims to do analysis of magnetic field and force distribution from the 3 dimensional modelling of a 1MW class superconducting synchronous motor. Especially. the field coil composed of Bi-2223 high-temperature superconductor and the outer machine shield are modelled by finite element analysis software according to their structures and the self-inductance and Lorentz force are calculated based on the 3 dimensional magnetic field calculation. Moreover. the influence of an important parameter, synchronous reactance, has been analyzed on the machine performances such as voltage variation and output power.
  9. Cho, Dae-Ho;Yang, S.E.;Kim, M.J.;Ahn, M.C.;Park, D.K.;Bae, D.K.;Seok, B.Y.;Ko, T.K. 37
    https://doi.org/10.9714/psac.2007.9.3.037 PDF KSCI
    Large critical current is one of the prerequisites for the design of superconducting electrical equipments with large power capacity. To enlarge the critical current. multiple parallel connection is inevitable. In multiple parallel superconducting coils. the difference in normal resistance of each shunt leads to unequal current distribution. which may yield burnout. Therefore. uniform current distribution is required for a stable operation of multiple parallel superconducting coils. In this paper, Rogowski coils were fabricated to measure each shunt current of a 4-parallel superconducting coil. Four Rogowski coils were installed at the copper bars, which are used as current leads in superconducting coils. As a result, linearity of the Rogowski coils was ascertained and coefficients of each coil, the ratio of voltage and current, were derived. The coefficients were compared with theoretically calculated values. Based on the coefficients, each shunt current was calculated in a 4-parallel superconducting coil, where uniform current. distribution was confirmed. This paper verified the feasibility of the fabricated Rogowski coils as well as operational stability of the 4-parallel superconducting coil in 77K.
  10. Lee, Sang-Il;Jeong, Sang-Kwon;Choi, Sung-Min;Park, Kap-Rai 41
    https://doi.org/10.9714/psac.2007.9.3.041 PDF KSCI
    This paper presents transport current non-uniformity in a joint for superconducting multistage cable-in-conduit conductor (CICC) and relaxation in the CICC. The joint is considered to have a current loop linked to an external magnetic field so that it becomes an emf voltage source. It is numerically analyzed using an electrical transmission line model. The inductive current in a resistive joint is compared to that of a non-resistive joint when the ramping field is applied vertically to the joints. Regarding the parameter values of the model. a full scale $Nb_3Sn$ CICC and a strand-to-strand (STS) joint for the toroidal field magnet of the KSTAR (Korea Superconducting Tokamak Advanced Research) device are referenced to. It is found that the resistive joint prevents the current from rising too much and enhances decaying the current when the ramping stops. The 'flattop' current is found to be proportional to the ramp rate of the field (dB/dt). The relaxation length, which is defined as the length within which the maximum induced current falls by 1/e. is found to saturate within 0.27m.
  11. Song, J.B.;Kim, J.H.;Kwon, N.Y.;Kim, Y.W.;Kim, H.M.;Sim, J.;Lee, B.W.;Kim, H.R.;Hyun, O.B.;Lee, H.G. 46
    https://doi.org/10.9714/psac.2007.9.3.046 PDF KSCI
    The 22.9kV/630A superconducting fault current limiter (SFCL) is developed by the KEPRI-LSIS collaboration group. This resistive SFCL uses three pairs of conduction-cooled current leads. When the SFCL system is in the fault mode. the current flows 20 times more than the steady state. Therefore. it is important that the current lead is designed to have the thermal stability in order to minimize the heat input of the cold-end. This paper presents the design and performance results of a pair of conduction-cooled brass current leads considering both cases that the SFCL system operates at the steady state and the fault current.
  12. Kwag, Dong-Soon;Cheon, Hyeon-Gweon;Choi, Jae-Hyeong;Min, Chi-Hyun;Kim, Hae-Jong;Cho, Jeon-Wook;Kim, Sang-Hyun 52
    https://doi.org/10.9714/psac.2007.9.3.052 PDF KSCI
    A high temperature superconducting (HTS) DC cable is ideal for transmitting large blocks of electrical power over a long distance. However, it must be designed to operate reliably within the constraints of the electrical systems. Therefore, a study of the electrical insulation is important to develop a HTS DC cable because it is operated in a cryogenic high voltage environment. This paper discusses the dielectric constructions of the cable and summarizes the experimental results on the DC and impulse dielectric characteristics of the insulation material. in sheet form and mini-model cable configuration. This shows how to design such insulation to be operated reliably. These studies are essential for the insulation design of a HTS DC cable operated in cryogenic environment.
  13. Sim, J.;Park, K.B.;Lim, S.W.;Kim, H.R.;Lee, B.W.;Oh, I.S.;Hyun, O.B. 57
    https://doi.org/10.9714/psac.2007.9.3.057 PDF KSCI
    The current limiting characteristics of hybrid SFCL with additional power electronic devices was investigated in order to improve operation reliabilities. The hybrid SFCL developed consists of a superconducting trigger (S/T) part, a fast switch (F/S) module and a current limiting (C/L) part. Although hybrid SFCL had shown a excellent current limiting characteristics, this device was rather vulnerable to the residual arc currents which could exist during fast switch operation. This undesirable arc should be extinguished as quickly as possible in order to implement perfect fault current commutation. So, in order to eliminate the residual arcs between fast switch contacts, the power electronic devices (IGBT or GTO) were connected in series between the S/T part and the interrupter of the F/S module. According to the fault tests conducting with an input voltage of $270\;V_{rms}$ and a fault current of $5\;kA_{rms}$, The power electronic devices could perfectly remove the arc generated between the contacts of the interrupter within 4 ms after the fault occurred. From the test analysis, it was confirmed that the hybrid SFCL could enhance the operation reliability by adopting additional power electronic devices.
  14. Kim, J.H.;Song, J.B.;Hwang, S.J.;Kim, K.L.;Kim, H.M.;Kim, H.R.;Hyun, O.B.;Ko, T.K.;Lee, H.G. 62
    https://doi.org/10.9714/psac.2007.9.3.062 PDF KSCI
    Electromagnetic forces (Attractive and repulsive force), interacting between current leads show different tendency according to the arrangement of current leads on the top flange of the cryostat and the distance of each lead. Especially in case of high-current electric power devices or high-field magnets, optimal arrangement of current leads becomes one of the safety issues to be considered for minimizing the electromagnetic for ce acting on them. In this paper, we suggest an optimal arrangement method with three pairs of current leads for a 24kV class 650A superconducting fault current limiter (SFCL) system which has a probability of unpredicted fault currents(i.e, 20kA).
  15. Choi, Jae-Hyeong;Kwag, Dong-Soon;Cheon, Hyeon-Gweon;Min, Chi-Hyun;Kim, Hae-Jong;Seong, Ki-Chul;Kim, Sang-Hyun 67
    https://doi.org/10.9714/psac.2007.9.3.067 PDF KSCI
    The electrical insulation design of 600 kJ conduction cooled high-Tc superconducting magnetic energy storage (SMES) have been studied in this paper. The high voltage is applied to both ends of magnet of high-Tc SMES by quench or energy discharge. Therefore. the insulation design of the high voltage needs for commercialization. stability. reliability and so on. In this study. we analyzed the insulation composition of a high-Tc SMES. and investigated about the insulation characteristics of the materials such as Kapton. AIN. $Al_2O_3$. GFRP and vacuum in cryogenic temperature. Base on these results. the insulation design for 600 kJ conduction cooled high-Tc SMES was performed.
  16. Cho, Nam-Kyung;Jeong, Sang-Kwon 72
    https://doi.org/10.9714/psac.2007.9.3.072 PDF KSCI
    This paper relates to reducing the temperature of a cryogenic liquid by contacting it with gas bubbles, which can be characterized by diffusion-driven evaporative cooling, The characteristic of diffusion-driven evaporative cooling is thoroughly examined by theoretical. analytical and experimental methods specifically for the case of helium injection into liquid oxygen. The results reveal that if the gaseous oxygen partial pressure in helium bubbles is lower than the liquid oxygen vapor pressure, cooling occurs autonomously due to diffusion mass transfer. The method of lowering the injected helium temperature turns out to be very effective for cooling purpose.