$Pr_1Ba_2Cu_3O_{7-δ}, Y_2O_3$ 혹은 MgO interlayer를 포함하는 고온 초전도 $Y_1Ba_2Cu_3O_{7-δ}$ 3중 박막의 I-V 특성에 관한 연구Study on Ⅰ-Ⅴ characteristics of high $T_c$ superconducting triple layered thin films $Y_1Ba_2Cu_3O_{7-δ}/ Pr_1Ba_2Cu_3O_{7-δ}/Y_1Ba_2Cu_3O_{7-δ}, Y_1Ba_2Cu_3O_{7-δ}/Y_2O_3/ Y_1Ba_2Cu_3O_{7-δ}$ and $Y_1Ba_2Cu_3O_{7-δ)/MgO/Y_1Ba_2Cu_3O_{7-δ}$