A method of operating a memory device includes performing a data read operation on at least one victim sub-block within a memory block containing a plurality of sub-blocks therein, in response to an erase command directed to a selected sub-block within the plurality of sub-blocks. Next, a soft program operation is performed on the at least one victim sub-block. This soft programming operation is then followed by an operation to erase the selected sub-block within the plurality of sub-blocks. This operation to erase the selected sub-block may include providing an erase voltage to a bulk region of a substrate on which the memory block extends, and the at least one victim sub-block may be disposed between the selected sub-block and the substrate.