A method of propping at least one fracture in a subterranean formation, that comprises forming a plurality of proppant aggregates, each proppant aggregate comprising a binding fluid and a filler material, and introducing the plurality of proppant aggregates into the at least one fracture, is provided. The outer component has a passage opening, through which the inner component projects out of the outer component. In this less-dust-generative matrix-type piezoelectricelectrostrictive device 1, a plurality of piezoelectricelectrostrictive elements 31 substantially having pillar shapes are set up in a matrix form. The control system is in operative communication with the data center. Therefore, it is possible to secure good communication quality even for a small-housing portable radio device. A control valve in one of the fluid channels openscloses the channel.