According to the type approval system introduced by the revised Railway Safety Act, The development of technical standards and test specifications for the type approval of domestic railway vehicles and equipment was conducted. However, the scope of application of type approval is set as existing general railway vehicles and supplies, and it is necessary to develop technical standards and test standards for type approval of urban magnetic levitation railway developed through domestic research. As a result, standard revision studies are being conducted on similar technologies between existing railways and magnetic levitation railways. This study investigates and analyzes the detailed provisions of the type approval technical standard corresponding to the insulator, In order to apply the performance criterion of urban magnetic levitation railway, supplementary study on existing general railway technical standard was conducted.

To develop a new standard design of gas-insulated bus (GIB), an electromagnetic-structural finite element analysis has been conducted considering the electromagnetic force generated in GIB with a large current. The GIB are electrical bus-bar parts of a gas-insulated switchgear(GIS) installed as a protective device in power plants and substations. Since the electromagnetic forces generated by a large current flowing through inner conductors of GIB tend to be very large, the structural integrity of the GIB should be evaluated. The magnetic force was calculated by the virtual work method and structural analysis was performed by utilizing the calculated force as a load condition. By modifying the designs based on the structural safety evaluation results, the maximum lengths of conductors could be increased by about 40~50%.

The magnetic relaxation of MgB 2 thin film deposited on Al 2 O 3 substrate by hybrid physical-chemical vapor deposition method was investigated. The rate of magnetic relaxation (the logarithmic decay rate) S, which was obtained by the time dependence of magnetic moment m(t) at fixed magnetic field H and temperature T, of the MgB 2 thin film was investigated. The decay of magnetic moment m(t) was carried out at temperatures between 5 and 37.5 K in the field ranges of 0.1-1.0 T, using PPMS-VSM (Quantum Design). The decrease of magnetic moment m(t) for 7200 s at T = 5 K was about 2%-3% and 0.2%-0.3% when the field was applied parallel to the c-axis and the ab-plane, respectively. The logarithmic decay rate S in the field parallel to the ab-plane was much smaller than that parallel to the c-axis over all temperature ranges. The time-independent behavior of logarithmic decay rate S at low temperatures below T = 10 K implies the presence of quantum creep effect.

This paper presents an electromagnetic-structural finite element analysis considering the electromagnetic force generated in the GIB(Gas Insulated Bus) by a large current. The GIB is electrical busbar part of a GIS(Gas Insulated Switchgear) installed in power plants and substations. Since the electromagnetic forces generated by currents flowing through inner conductors in the GIB are so large, they have to be considered in the structural safety evaluation of a GIB. The magnetic force was calculated by the virtual work method and structural analysis on a GIB under loaded condition was performed. By modifying the designs based on this structural safety evaluation results, the safety factor has been enhanced from 1.2 to 3.75.

MgB 2 powders were treated for different amount of time in diluted water (water-ethanol mixture) with two different water-to-ethanol ratios of 12: 18 and 6:24 to investigate the effect of diluted water-treatment on the superconducting properties of MgB 2 . The diluted water-treatment did not affect the phase composition of the powder. The magnetic moment measurement of both untreated and treated MgB 2 powders showed the degradation of irreversible magnetic moment of the powders as the treatment time increases. The change of irreversible magnetic moment was explained by the dissolution of Mg and B into the diluted water during the treatment. The amount of dissolved substances after the treatment measured by chemical analyses (ICP MS) showed that the concentration of B dissolved in the diluted water is much larger than that of Mg, as the treatment time increases. The contact of MgB 2 with the water or moisture has to be considered in the design of the superconducting devices based on the MgB 2 to prevent the degradation of the superconducting properties of the devices.

중이온 입자가속기는 중이온을 radio frequency (RF) 주파수로 가속하는 장치이다. RF 공동부에 인가된 전기장은 입력된 RF 파에 의해 전자기파의 위상에 맞춰 중이온을 연속적으로 가속한다. 이를 위해서는 안정적으로 RF 파를 공동부 내부에 전달할 수 있는 커플러의 형상설계가 요구된다. 중이온 가속기에서의 RF 커플러는 입력부와 RF 주파수의 파를 방출하는 커플러 양 끝단 간의 온도차이가 매우 크다. 이 온도차를 극복하기 위해선 초저온(약 0K)부터 상온 간(약 300K)의 열 변형을 고려한 해석 및 설계기술이 필요하다. 본 연구는 RF 커플러의 구조에 따른 출력 전기장의 세기와 온도 분포, 열 손실과 열변형을 고려한 내구도 분석을 통해 성능 향상을 위한 방안들을 도출하는 것을 목적으로 하였다.

A novel and simple electromagnetic actuation (EMA) system having a permanent magnet (PM) type micro-robot and external coil pairs is proposed. The micro-robot is composed of PM and the newly proposed EMA system consists of only two coil pairs arranged along x- and y-axis, respectively, allowing different current intensity into each coil to derive torque and thrust force on the horizontal plane. Magnetic fields generated by the EMA system are analyzed through the finite element analysis and numerical results are compared with the theoretical analysis to verify the feasibility of the proposed system. A prototype system is manufactured and its performance is verified by comparison of magnetic flux values.

This paper proposes a simplified electromagnetic actuation system for the motion control of a micro-robot. The proposed system uses only two pairs of Helmholtz coils for two-dimensional motion generation, while conventional systems use two pairs of Helmholtz coils and Maxwell coils, respectively. It can make the system smaller and increase the workspace of the micro-robot. And also, power consumption can be lower. To verify the feasibility of the proposed system, force analysis and basic experiments were performed.

To examine the effect of diluted water treatments on the superconducting properties of MgB2, MgB2 powders were prepared by mixing with a series of diluted water (water-ethanol mixture). XRD analyses were carried out to investigate the phases of the diluted water-treated MgB2 powders. Both the isothermal magnetizations M(H) of the series of samples at fixed temperature and M(T) in fixed field, employing a PPMS-9 (Quantum Design), were measured. The degradation of the superconductivity of MgB2 by the diluted water treatments was observed. The diluted water-treated MgB2 powders have shown reduced superconductivity as the water concentration in the diluted water increases.

Sm1+xBa2−xCu3+yO7−δ (SmBCO) films were directly deposited on the epi-MgO/IBAD-MgO/Y2O3/Al2O3/Hastelloy template by co-evaporation using the evaporation using drum in dual chambers (EDDC) system without the buffer layer in order to investigate the effect of the composition ratios on superconducting property, microstructure and texture of SmBCO film. The films with gradient composition ratios of Sm:Ba:Cu were deposited using a shield with an opening which was placed between the substrate and the boats. The highest Ic of 52A (corresponding to Jc=1.6MA/cm2 and a thickness of 800nm) was observed at 77K in self field at a composition x=0.01–0.05 and y=−0.23 to −0.46. When the composition ratio is outside this range, the Ic value rapidly decreased. The superconducting critical current was highly dependent on the composition ratio. As the composition ratio is farther away from that of the highest Ic, the SmBCO (103) peak intensity increased and the amount of a-axis oriented parts increased. A dense microstructure with round-shape grains was observed in the region showing the highest Ic. The optimum composition ratio can be found by analyzing films deposited with variable deposition rates of each depositing element.

The growth and properties of undoped and Mn-doped ZnGa2O4 thin-film phosphors on (100) MgO and glass substrates using pulsed laser ablation were investigated. Blue-white and green emission were observed for as-deposited undoped and Mn-doped films, respectively. Luminescent properties as well as crystallinity were considerably affected by processing conditions and film stoichiometry. Films with enhanced luminescent characteristics were obtained on single crystal substrates without post-annealing.

The magnetic properties of high Tc superconductor (HTS) SmBa2Cu3O7−δ (SmBCO) coated conductors (CCs) which are based on IBAD (ion-beam-assisted deposition) templates were investigated. The SmBCO CCs were fabricated on LaMnO3(LMO)/epi-MgO/IBAD-MgO/Hastelloy substrates by Evaporation using Drum in Dual Chamber (EDDC) processing. The measurements of isothermal magnetizations M(H) for the prepared SmBCO-CCs were carried out at various temperatures in magnetic fields up to 8.5T. The magnetic properties for the applied magnetic fields parallel to the ab-plane show non-conventional behaviors when compared to those parallel to both c-axis and c-axis+45°. These normal and anomalous properties can be explained by introducing the magnetic flux pinning effects related to the direction of the applied magnetic fields.

High quality GdBa2Cu3O7-δ (GdBCO) coated conductors (CCs) were successfully fabricated on CeO2-buffered IBAD MgO template by pulsed laser deposition (PLD). With the same energy density of 2 J/cm2, laser frequency of 8 Hz, and oxygen pressure of 300 mTorr, both target-to-substrate distance (Dts) and substrate temperature (Ts) were systematically varied from 5.5 to 4.0 cm at Ts of 780 °C and from 760 to 820 °C at Dts of 4.5 cm, respectively, to investigate their effects on the grain alignment, microstructure, and superconducting properties of GdBCO films. Biaxially aligned GdBCO films without a-axis oriented GdBCO grains could be deposited at Ts higher than 780 °C and Dts shorter than 5.0 cm. At Ts of 760 °C, a small amount of a-axis oriented and 45° misaligned GdBCO grains was formed. The in-plane textures of GdBCO films were gradually improved when Dts decreased, while those were first improved with increasing Ts up to 800 °C and then degraded at 820 °C. The highest critical current density (Jc) of 3.9 MA/cm2 and critical current (Ic) of 195 A/cm-width (77 K, self-field) were achieved from the 500 nm GdBCO film deposited at 800°C with Dts of 4.5 cm . The Jc values of GdBCO films were found to be sensitive to the in-plane texture and also to the presence of a -axis oriented grains and 45° misaligned grains.

We report the effects of BSO addition on the crystallinity, texture, and the field dependency of critical current density (Jc) of GdBCO coated conductors (CCs) prepared by pulsed laser deposition (PLD). Undoped and BSO-doped GdBCO films showed only c-axis oriented growth, and the incorporated BSO nanorods exhibited epitaxial relationship with the GdBCO matrix. In comparison with undoped film, BSO-doped GdBCO film exhibited greatly enhanced Jc and higher pinning force densities in the entire field region of 0–5 T (H//c) at 77 and 65 K. The BSO-doped GdBCO film showed the maximum pinning force densities (Fp) of 6.5 GN/m3 (77 K, H//c) and 32.5 GN/m3 (65 K, H//c), ∼2.8 times higher than those of the undoped sample. Cross-sectional TEM analyses exhibited nano-structured BSO nanorods roughly aligned along the c-axis of the GdBCO film, which are believed effective flux pinning centers responsible for strongly improved critical current densities in magnetic fields.

A cryogenic insulation technique for a high voltage and a large current capacity of a conductor are now two big issues in a field of recent R&D projects of superconducting power devices, especially a superconducting power transformer. For the large rated currents of the power transformer, it is well known that lots of 2nd generation superconducting conductor, so called coated conductor, should be stacked together with transpositions in order to get an even distributions of the currents. We had come up with an idea of a CTCC (Continuously Transposed Coated Conductor) as a conductor for a large power superconducting transformer, and keep trying to verify the usefulness of the conductor. As one of the efforts of verifying, we prepared and tested a sample CTCC with insulations for high voltage, which includes the epoxy coating and Nomex wrapping. This paper contains the insulation process and dielectric breakdown test results. We expect the results obtained from this experiment to improve an insulation technique for high voltages in various cryogenic environments[1,2].

The nanoparticle–MgB2 composite superconducting sample, (SiC)4wt.%(MgB2)96wt.% ((SiC)4–MgB2), was prepared, and the effect of nanoparticle additions on the magnetic flux pinning was investigated. The measurement and comparison of isothermal magnetization M(H), for pure-MgB2 powder and sintered pellets of (SiC)4–MgB2 and pure-MgB2 were carried out at temperatures between 5 and 50K in fields up to 8.5T. The magnetic irreversibility ΔM(H) curves of the (SiC)4–MgB2 follow almost identical lines of both pure-MgB2 powder and sintered bulk MgB2 in the region above a specific magnetic field (called a merged field), which gradually decreases as the temperature increases. The (SiC)4–MgB2 composite superconductor has exhibited the flux pinning effect which comes from both the grain boundaries and the point defect weak pinning centers in the region below the merged field line. This is different from the case of pure-MgB2 powder and sintered bulk MgB2 which showed mostly the grain boundaries pinning.