A method of erasing a logical data block of a MRAM according to an embodiment of the present invention is disclosed. For example, various embodiments of the present invention provide semiconductor devices that include a power source and a phase lock loop circuit. A fuel distributor for fuel supply duct is thus arranged. When a catalyst is in an inactivated state, the variable-valve mechanisms are controlled to reduce the amount of residual gas leaking out from cylinders. The outer fin regions comprise a strain inducing material that stresses the center semiconductor fin region.