Korea's developmental program for superconductivity

Superconductivity research in Korea was firstly carried out in the late 70's by a research group in Seoul National University (SNU), who fabricated a small scale superconducting magnetic energy storage system under the financial support from Korea Electric Power Company (KEPCO). But a few researchers were involved in superconductivity research until the oxide high Tc superconductor was discovered by Bednorz and Mueller. After the discovery of YBaCuO superconductor operating above the boiling point of liquid nitrogen (77 K)(exp 2), Korean Ministry of Science and Technology (MOST) sponsored a special fund for the high Tc superconductivity research to universities and national research institutes by recognizing its importance. Scientists engaged in this project organized 'High Temperature Superconductivity Research Association (HITSRA)' for effective conducting of research. Its major functions are to coordinate research activities on high Tc superconductivity and organize the workshop for active exchange of information. During last seven years the major superconductivity research has been carried out through the coordination of HITSRA. The major parts of the Korea's superconductivity research program were related to high temperature superconductor and only a few groups were carrying out research on conventional superconductor technology, and Korea Atomic Energy Research Institute (KAERI) and Korea Electrotechnology Research Institute (KERI) have led this research. In this talk, the current status and future plans of superconductivity research in Korea will be reviewed based on the results presented in interim meeting of HITSRA, April 1-2, 1994. Taejeon, as well as the research activity of KAERI

Parallel Computing Application on Combustion and Emission Analysis of an Annular Gas Turbine Combustor

To analyze the emissions of a turbulent leanpremixed Methane-air combustor, a level set Gequation method has been implemented in the LargeEddy Simulation (LES) framework using parallelpersonal server. The server consists of 36 nodes with12 CPU cores a node. GRI-MECH 3.0 which is acompilation of 325 elementary chemical reactions with53 species, has been used with Presumed-ProbabilityDensity Function (PDF) method. The combustionflames from each injector move extremely dynamicallyand rotate in different directions from adjacentinjectors because the swirl directions of each injectorare opposite to the adjacent injectors. CO has highconcentration on the flame and disappears rapidlyafter the flame due to the lean premixed conditions. NOmole fraction increases continuously after the flameand then is emitted at the exit of combustor

Chemical modification of precursor solution for long length YBCO coated conductor fabrication

Long length MOD processing of YBCO conductor requires high performance precursor solution without degradation during the process. In this study, effect of chemical modification of precursor solution on MOD processing was investigated to meet the requirement. Highly stable YBCO precursor solution was synthesized with PVP (polyvinylpyrrolidone) and crack-free thick precursor film was successfully fabricated. However, annealed YBCO film shows porous microstructures originated from large HF gas generation from thick films and residual carbon from additives. Reduction of fluorine content is required to densify microstructures. In order to reduce fluorine content, F-free Cu-precursor solution was synthesized. YBCO film with Jc = 0.8MA/cm2 was grown on buffered RABiTS tape. Annealed YBCO film still contains pores and further reduction of pores is required to improve critical current (Ic

Fabrication of silver stabilization layer of coated conductor using organic silver complexes

Silver stabilizing layer of coated conductor has been prepared by dip coating method using organic silver complexes containing 10 wt.% silver as a starting material. Coated silver complex layer was dried in situ with hot air and converted to crystalline silver by post heat treatment in flowing oxygen atmosphere. A dense continuous silver layer with good surface coverage and proper thickness of 230 nm is obtained by multiple dip coatings and heat treatments. The film heat treated at 500 °C showed good mechanical adhesion and crystallographic property. The interface resistivity between superconducting YBCO layer and silver layer prepared by dip coating was measured as 0.67 × 10−13 Ω m2. Additional protecting copper layer with the thickness of 20 μm was successfully deposited by electroplating. The critical current measured with the specimen prepared by dip coating and sputtering on same quality YBCO layer showed similar value of ∼140 A and proved its ability to replace sputtering method for industrial production of coated conductor