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REFERENCE LINKING PLATFORM OF KOREA S&T JOURNALS
> Journal Vol & Issue
Progress in Superconductivity and Cryogenics
Journal Basic Information
Journal DOI :
The Korea Institute of Applied Superconductivity and Cryogenics
Editor in Chief :
Volume & Issues
Volume 7, Issue 4 - Nov 2005
Volume 7, Issue 3 - Sep 2005
Volume 7, Issue 2 - May 2005
Volume 7, Issue 1 - Mar 2005
Selecting the target year
Observing Thermal Counterflow in He II by the Particle Image Velocimetry Technique
Van Sciver S. W. ;
Progress in Superconductivity and Cryogenics, volume 7, issue 2, 2005, Pages 1~6
The Particle Image Velocimetry (PIV) technique can be used to obtain a whole-field view of thermal counterflow velocity profile in He II. Using commercially available microspheres, we have been able to visualize the normal fluid velocity in He II thermal counterflow; however, the measured velocities are less than predicted from the two fluid model. None the less, the PIV is a useful tool for observing the counterflow field in He II flow, particularly where the flow is complex as occurs through channel constrictions or around bluff objects. The present paper shows recent results using PIV to observe He II counterflow. Two cases are discussed: 1D channel flow and turbulent flow around a circular cylinder.
Magnetism in Ni-W textured substrates for coated conductors
Song K. J. ; Park Y. M. ; Yang J. S. ; Kim S. W. ; Ko R. K. ; Kim H. S. ; Ha H. S ; Oh S. S. ; Park C. ; Joo J. H. ; Kim C. J. ;
Progress in Superconductivity and Cryogenics, volume 7, issue 2, 2005, Pages 7~10
The magnetic properties of a series of both annealed (biaxially textured) and as-rolled (non-textured) Ni-xW alloy tapes with compositions x = 0,1,3, and 5 at.
, were studied. Characterization methods included XRD analyses to investigate the biaxial cube texturing of the annealed Ni-W alloy tapes and studies of the magnetization M for both annealed and as-rolled Ni-W alloy tapes. Both the isothermal mass magnetizations M(H) of a series of samples at different fixed temperatures and M(T) in fixed field, employing a PPMS-9 (Quantum Design), were measured. The Ni-W alloys have shown much reduced ferromagnetism as W-content x increases. Both the saturation magnetization Msat and Curie temperature Tc decrease linearly with W-content x, and both Msat and Tc go to zero at critical concentration of Xc - 9.50 at.
Influences of Bending Temperature on the I
Degradation Behavior of Bi-2223 tapes under Bending
Shin Hyung Seop ; Dizon John Ryan C. ; Katagiri Kazumune ; Kuroda Tsuneo ;
Progress in Superconductivity and Cryogenics, volume 7, issue 2, 2005, Pages 11~15
degradation behavior of Bi-2223 tapes bent at RT and 77K were investigated using the bending device invented by Goldacker. Test results on fixing the tape at RT and 17K showed no difference. At 17K and RT bending, the critical strain was 0.67 and 0.50
, respectively, for the VAM-l tape. For the AMSC tape, it was 0.94 and 0.88
, respectively. These results show that there is additional residual stress in the superconducting filaments to be bent at 17K which shifts the formation of cracks into smaller bending radii. This was proved by computational analysis based on the mixture rule of composites. For the VAM-l tape, the Ie degradation behavior using the Goldacker type device shifted to higher strain levels at about 0.5
, as compared with the FRP sample holders which have a critical bending strain of about 0.24
. Also, for the externally reinforced AMSC tape, Ie degradation using the Goldacker type device begins at a higher strain level, at 0.88
as compared with using FRP sample holders, at 0.74
. The difference between both cases can be explained by the tensile' and thermal stresses that the tapes were subjected to during fixing (soldering) when the FRP sample holders were used.
Comparison of Fault Current Reduction Effects by the SFCL Introduction Locations
Kim Jong Yul ; Lee Seung Ryul ; Yoon Jae Young ;
Progress in Superconductivity and Cryogenics, volume 7, issue 2, 2005, Pages 16~20
As power systems grow more complex and power demands increase, the fault current tends to gradually increase. In the near future, the fault current will exceed a circuit breaker rating for some substations, which is an especially important issue in the Seoul metropolitan area because of its highly meshed configuration. Currently, the Korean power system is regulated by changing the 154kV system configuration from a loop connection to a radial system, by splitting the bus where load balance can be achieved, and by upgrading the circuit breaker rating. A development project applying 154kV Superconducting Fault Current Limiter (SFCL) to 154kV transmission systems is proceeding with implementation slated for after 2010. In this paper, SFCL is applied to reduce the fault current in power systems according to two different application schemes and their technical impacts are evaluated. The results indicate that both application schemes can regulate the fault current under the rating of circuit breaker, however, applying SFCL to the bus-tie location is much more appropriate from an economic view point.
Breakdown Characteristics and Survival Probability of Turn-to- Turn Models for a HTS Transformer
Cheon H.G. ; Baek S.M. ; Seong K.C. ; Kim H.J. ; Kim S.H. ;
Progress in Superconductivity and Cryogenics, volume 7, issue 2, 2005, Pages 21~26
Breakdown characteristics and survival probability of turn-to-turn models were investigated under ac and impulse voltage at 77K. For experiments, two test electrode models were fabricated: One is point contact model and the other is surface contact model. Both are made of copper wrapped by O.025mm thick polyimide film(Kapton). The experimental results were analyzed statistically using Weibull distribution in order to examine the wrapping number effects on voltage-time characteristics under ac voltage as well as under impulse voltage in LN
. Also survival analysis were performed according to the Kaplan-Meier method. The breakdown voltages of surface contact model are lower than that of point contact model, because the contact area of surface contact model is wider than that of point contact model. Besides, the shape parameter of point contact model is a little bit larger than that of surface contact model. The time to breakdown t
is decreased as the applied voltage is increased, and the lifetime indices slightly are increased as the number of layers is increased. According to the increasing applied voltage and decreasing wrapping number, the survival probability is increased.
Development of a 3MJ/750kV A SMES System
Kim Hae-Jong ; Seong Ki-Chul ; Cho Joon-Wook ; Bae Joon-Han ; Sim Ki-Deo ; Ryu Kyung-Woo ; Kime Sang-Hyun ;
Progress in Superconductivity and Cryogenics, volume 7, issue 2, 2005, Pages 27~30
Research and development on superconducting magnetic energy storage (SMES) system have been done to realize efficient electric power management for several decades. Korea Electrotechnology Research Institute (KERI) has developed a 3MJ/750kV A SMES system to improve power quality in sensitive electric loads. It consists of an IGBT based power converter, NbTi mixed matrix Rutherford cable superconducting magnet, and a cryostat with HTS current leads. A computer code was developed to find the parameters of the SMES magnet which has minimum amount of superconductors for the same stored energy, and the 3MJ SMES magnet was designed based upon that. This paper describes the fabrication and experimental results of a 3MJ/750kV A SMES system.
Current Limitation by Bi-2223 Bifilar Winding Coils
Ahn Min Cheol ; Bae Duck Kweon ; Park Dong Keun ; Yang Seong Eun ; Yoon Yong Soo ; Ko Tae Kuk ;
Progress in Superconductivity and Cryogenics, volume 7, issue 2, 2005, Pages 31~34
There are many kinds of high temperature superconducting (HTS) application using Bi-2223 tape which is the most commercialized HTS material. Also, resistive superconducting fault current limiters (SFCLs) have been developed using many kinds of superconducting material such as YBCO thin film, Bi-2212 bulk and so on. However, SFCL using Bi-2223 tape has never been developed. This paper deals with the feasibility study on SFCL using Bi-2223 wire. The over-current behaviors of Bi-2223 short-length sample were measured. To make the resistive SFCL, two small-scale bifilar winding modules using 7m Bi-2223 wire were fabricated; i.e. solenoid type bifilar coil and pancake type one. The short-circuit tests of the coils were successfully performed up to 16 V
From these tests, the current limiting capabilities of Bi-2223 bifilar coils were confirmed and current limiting performances between two winding types were compared. In addition, the feasibility of resistive SFCL using another HTS wire, i.e. YBCO coated conductor, was also investigated.
R-type HTS-FCL Model considering transient characteristics
Yoon Jae Young ; Lee Seung Ryul ; Kim Jong Yul ;
Progress in Superconductivity and Cryogenics, volume 7, issue 2, 2005, Pages 35~38
One of the most serious problems in KEPCO system operation is higher fault current than the SCC(Short Circuit Capacity) of circuit breaker. There are many alternatives to reduce the increased fault current such as isolations of bus ties, enhancement of SCC of circuit breaker, applications of HVDC-BTB(Back to Back) and FCL(fault current limiter). But, these alternatives have some drawbacks in viewpoints of system stability and cost. As the superconductivity technology has been developed, the resistance type HTS-FCL(High Temperature Superconductor Fault Current Limiter) can be one of the most attractive alternatives to solve the fault current problem. To evaluate the accurate transient performance of resistance type HTS-FCL, it is needed that the dynamic simulation model considering transient characteristics during quenching and recovery state. Under this background, this paper presents the EMTDC model for resistance type HTS-FCL considering the nonlinear characteristic of final resistance value when quenching and recovery phenomena by fault current injection and clearing occurs.
Insulation Characteristics for a Conduction-Cooled HTS SMES
Cheon H.G. ; Baek S.M. ; Seong K.C. ; Kim H.J ; Kim S.H. ;
Progress in Superconductivity and Cryogenics, volume 7, issue 2, 2005, Pages 39~43
Toward the practical applications, on operation of conduction-cooled HTS SMES at temperatures well below 77 K should be investigated, in order to take advantage of a greater critical current density of HTS and considerably reduce the size and weight of the system. Recently, research and development concerning application of the conduction-cooled HTS SMES that is easily movement are actively progressing in Korea. Electrical insulation under cryogenic temperature is a key and an important element in the application of this apparatus. However, the behaviors of insulators for cryogenic conditions in air or vacuum are virtually unknown. Therefore, this work focuses on the breakdown and flashover phenomenology of dielectrics exposed in vacuum for temperatures ranging from room temperature to cryogenic temperature. Firstly, we summary the insulation factors of the magnet for HTS SMES. And a surface flashover as well as volume breakdown in air and vacuum has been investigated with two kind insulators. Finally, we will discuss applications for the HTS SMES including aging studies on model coils exposed in vacuum at cryogenic temperature.
Characteristics of an HTS SMES for Solar Power System
Kim Woo-Seok ; Lee Seung-wook ; Hahn Song-yop ;
Progress in Superconductivity and Cryogenics, volume 7, issue 2, 2005, Pages 44~46
A SMES can be a perfect alternative energy storage device to the chemical batteries which are needed by most of the renewable energy supply systems. The chemical battery storage system is so expensive to maintain and causes another environmental problem because they are not recyclable. But, SMES has semi-permanent lifetime and no environmental problems cause it only need coolants which is non flammable, clean and recyclable gas. In order to verify the feasibility of a SMES for the renewable electrical power supply system, electrical characteristics of a test SMES coil with the photovoltaic power system were analyzed in this paper. Simulation results show that we can charge 40 amps of current in test SMES coil using solar power system. The experimental verification will be performed just after development of the peak power tracking system for the solar system.
A study on SFCL application for the interconnection operation of 154kV power systems under 345kV S/S in Korean power system
Lee Seung Ryul ; Kim Jong Yul ; Yoon Jae Young ;
Progress in Superconductivity and Cryogenics, volume 7, issue 2, 2005, Pages 47~51
This paper is for studying the feasibility of SFCL application for the interconnection operation of 154kV power systems under 345kV S/S in Korean power system. All Korean 154kV power systems are constructed as loop systems in downtown. However, the present 154kV systems are operated with separated systems around 345kV S/S because of fault current and overload problems. In this study, we investigate the structure and operation of 154kV power system in Seoul and study the feasibility of interconnection operation of 154kV systems under 345kV systmes by applying SFCLs to 154kV bus-tie.