• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1998.06a
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• pp.355-357
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• 1998

BSCCO-2223 superconducting tape made by PIT method can be influenced in the critical characteristics by the heat treatment and the mechanical processing. Particulary, it has been reported that the mechanical deformation affects the core density, texture of the core, sausaging and so on. Therefore the accurate control of the deformation process is very important to achieve high J$\sub$c/. In this study, we measured the J$\sub$c/ variation for different rolling reduction rate and investigated the change of core shape to compare the formation of sausaging.

• Progress in Superconductivity and Cryogenics
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• v.21 no.4
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• pp.34-38
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• 2019

Multilayered high-temperature superconductor coated conductor (CC) tapes are used in an extensive range of applications and are exposed to many stresses such as hoop stress, radial/transverse tensile stress under large Lorentz forces, and thermal stress while cooling if thermal expansion properties differ. Loads induced transversely at the tape surface inevitably create delamination phenomena in the multilayered CC tapes. Thus, delamination behaviors of CC tapes along the c-axis under transverse loading conditions, which can vary based on manufacturing process and constituent layers, must be characterized for applications. The anvil test method was used to mechanically investigate the delamination characteristics of various commercially available Ag-stabilized CC tapes at room temperature and 77 K, finding superior strength at the latter. The wide variations found depended on tape structure and fabrication technique. Fractographic morphologies of delaminated tapes supported the findings under transverse loading conditions.

• Progress in Superconductivity and Cryogenics
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• v.9 no.4
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• pp.7-10
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• 2007

The transport current distribution across the tape width of a SmBCO coated conductor was investigated. The current distribution was estimated by applying an inversion process to the field distribution measured in the vicinity of the tape by using a scanning Hall probe method. The obtained result is well consistent with one predicted by the Bean model, however, at the edges the current are not constant and do not generally plateau, on the contrary.

• Proceedings of the International Microelectronics And Packaging Society Conference
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• 2001.07a
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• pp.151-156
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• 2001

Using the photoimageable thick film conductors, $25\mu\textrm{m}$ line widths and $25\mu\textrm{m}$ spaces can be obtained. Test patterns are made by green tape lamination, paste printing, exposing to UV light, developing in an aqueous process and cofiring. Postfiring method using alumina substrate can be also applied to fine line formation. Series gap resonator formed by photopatterning process showed the improved signal transmission characteristics compared to that obtained by conventional screen printing.

• Progress in Superconductivity and Cryogenics
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• v.9 no.1
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• pp.18-21
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• 2007

Highly textured MgO template by ion-beam-assisted deposition(IBAD) was successfully fabricated using a continuous reel-to-reel(R2R) mode. To enlarge the deposition area, the previous IBAD system was modified into the system with 14-pass and five heating zone. Every processing step was carried out using this multi-turn IBAD system. The overall process consists of R2R electropolishing of a hastelloy C276 tape, deposition of $Al_2O_3$ diffusion barrier, $Y_2O_3$ seed layer, IBAD-MgO and homoepi-MgO layer. The IBAD-MgO templates were fabricated using the IBAD system with 216 cm-length deposition zone and 32 cm diameter ion source. The texture of MgO films developed during the IBAD process was monitored by in-situ reflection high energy electron diffraction(RHEED) to optimize the IBAD process. Recently, 100 m long IBAD-MgO tape with in-plane texture of $\Delta{\phi}<10^{\circ}$ was successfully fabricated using the modified IBAD system. In this report, the detailed deposition condition of getting a long length IBAD-MgO template with a good epitaxy is described.

• Progress in Superconductivity and Cryogenics
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• v.7 no.3
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• pp.9-12
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• 2005

[ $Y_1Ba_2Cu_3O_{7-8}$ ] (YBCO) coated conductor has been fabricated by batch-type process using oxide-precursor-based metal-organic deposition (MOD) method. The batch-type process can be scaled up more simply to Produce long-length YBCO conductor than the reel-to-reel process. Also, it has less handling problems and is adequate to the ambient gas environment. In this work, YBCO oride powder was used as a starting precursor for MOD method. After reel-to-reel dip coating process, me ter-long-buffered metal tape was wound around a cylinder and underwent calcination and annealing processes. Annealed YBCO films showed good c-axis alignment and dense surface morphology with no cracks, but exhibited very low critical current density of $10^5\;A/cm^2$.

• Journal of the Korean School Mathematics Society
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• v.5 no.2
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• pp.23-31
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• 2002

The purpose of this study is to analyze thinking process in problem solving and to get some teaching materials to improve students' problem solving abilities. For this study, 14 girl and boy students in highschool were tested with 7 testing questions. The whole process of students' problem solving was observed by using 'Thinking aloud', recorded by Audio Tape and finally drawn up to Protocol. On the basis of that Protocol, coding system was set up and characteristics of thinking process in each stage were analyzed. -In the stage of planning, successful problem solvers tried to check the properties of words included in problems(Pr) and made it clear that they were seeking(O) -In the stage of planning, students used abstraction strategy(Ab, making equation(E) or using variable(V)) appropriately could solve more difficult problems. Successful problem solvers turned used unsystematical trial into systematical method and were good at using partial objects, assistant factors. - In the stage of carring out the plan, successful problem solvers to reduce the error, check the purpose, used formula, knowledge and calculation. -In the looking back stage, successful problem solvers generalized the answer and checked the total process.

• Proceedings of the KSME Conference
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• 2003.11a
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• pp.1888-1891
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• 2003

In this paper, we proposed a new method to control the length of carbon nano tube in the single CNT probe. A single CNT probe was composed of a tungsten tip made by the electrochemical etching and carbon nano tube which was grown by CVD and prepared through the sonication. The two components were attached with the carbon tape. Since the length of CNT can not be controlled during the manufacturing, the post process is needed to shorten the CNT. In this paper, we proposed the method of electrochemical process. The process was done under the optical microscope and the results were checked by SEM. The diameter of the carbon nano tube used in this paper was about 130nm because the above process had to be done with the optical microscope. Using the method proposed in this paper, we can control the length of the nano tube tip.

• Journal of Powder Materials
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• v.23 no.5
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• pp.379-383
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• 2016

A thick film of $Li_7La_3Zr_2O_{12}$ (LLZO) solid-state electrolyte is fabricated using the tape casting process and is compared to a bulk specimen in terms of the density, microstructure, and ion conductivity. The final thickness of LLZO film after sintering is $240{\mu}m$ which is stacked up with four sheets of LLZO green films including polymeric binders. The relative density of the LLZO film is 83%, which is almost the same as that of the bulk specimen. The ion conductivity of a LLZO thick film is $2.81{\times}10^{-4}S/cm$, which is also similar to that of the bulk specimen, $2.54{\times}10^{-4}S/cm$. However, the microstructure shows a large difference in the grain size between the thick film and the bulk specimen. Although the grain boundary area is different between the thick film and the bulk specimen, the fact that both the ion conductivities are very similar means that no secondary phase exists at the grain boundary, which is thought to originate from nonstoichiometry or contamination.

• Progress in Superconductivity and Cryogenics
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• v.19 no.2
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• pp.25-28
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• 2017

In superconducting coil applications particularly in wet wound coils, coated conductor (CC) tapes are subjected to different type of stresses that could affect its electromechanical transport property. These include hoop stress acting along the length of the CC tape and the Lorentz force acting perpendicular to the CC tape's surface. Since the latter is commonly associated with the delamination problem of multi-layered REBCO CC tapes, more understanding and attention on the delamination phenomena induced in the case of coil applications are needed. Difference on the coefficient of thermal expansion (CTE) of each constituent layer of the CC tape, the bobbin, and the impregnating materials is the main causes of delamination in CC tapes when subjected to thermal and mechanical cycling. In the design of degradation-free superconducting coils, therefore, characterization of the delamination behaviors including mechanism and strength in the multi-layered REBCO CC tapes becomes a critical issue. Various trials to increase the delamination strength by improving interface characteristics at interlayers have been performed. In this study, in order to investigate the influences of laser cleaning and Ag annealing treated at the substrate side surface, transverse tensile tests were conducted under different sample configurations using $4.5mm{\times}8mm$ upper anvil. The mechanical delamination strength of differently processed CC samples was examined at room temperature (RT). As a result, the Sample 1 with the additional laser cleaning and Ag annealing processes and the Sample 2 with additional Ag annealing process only showed higher mechanical delamination strength as compared to the Sample 3 without such additional treatments. Sample 3 showed quite different behavior when the loading direction is to the substrate side where the delamination strength much lower as compared to other cases.