Apparatus and methods associated with a center finder and marking tool are disclosed. The automatic gain controller and method analyze background noise by operating a microphone mounted in a mobile communication terminal and automatically control the gain of the signal part which is non-audible due to the background noise. The extractor extracts the similar performer using a relation between a plurality of performers. The gaming applications include gambling, financial, entertainment service, and other types of transactions. The plasma etch chamber also including an upper electrode disposed opposite from the top surface of the substrate support. The flow conditioner has a lumen tapering in the direction of the measuring tube.