Several defects in a smectic-A phase in an isotropic phase have been observed in the binary mixture of octyloxycyanobiphenyl and dodecyl alcohol using a polarizing microscope. Polarizing-microscope images are simulated to determine the structures of the smectic-A defects. The observed defect structures are classified according to the strength of the defects (2pim). The values of m observed here are confirmed to be an integer or a half integer and are \m\ less than or equal to 1.