高温超伝導材料を利用した次世代NMR技術の開発;高電流密度コイル化技術の構築(1)-電磁力評価用REBCOコイル#1, #2の製作- (Development of the next-generation NMR technology using HTS materials; For achievement of HTS coil with high operating current density (1) - Fabrication of REBCO #1 and #2 coils for tests under electro-magnetic forces - )