An apparatus and method for prefetching cache data in response to data requests. A light source and a template are attached to the drill so that an image is projected onto the workpiece surface. The method may further include calculating a second elevation value of a ground-engaging device of the machine in the gravity reference frame of the machine. The product is surface-treated over at least a portion of the external surface with a composition having softening properties and including at least one surfactant. That is, the light emitting element of the present invention is able to be produced by using a silicon material, which is available at low price, through a simple production method, and efficiently emit light. Therapeutic agents can be delivered nto cells of muscle for local and systemic treatments with optimal gene expression and minimal tissue damage.