Abstract: A substrate processing apparatus includes: a mixer configured to mix sulfuric acid as a first component and a second component different from the first component to prepare an etchant; a nozzle configured to eject the etchant to a substrate; a first component supplier including a first flow path that supplies the first component to the mixer, a first instantaneous flowmeter and a first flow rate controller provided in the first flow path; a second component supplier including a second flow path different from the first flow path and configured to supply the second component to the mixer, a second instantaneous flowmeter and a second flow rate controller provided in the second flow path; and a controller configured to control the first and second flow rate controllers using average flow rates of the first component and the second component during the ejection of the etchant to the substrate.

Abstract: There is provided an under-run protector which is light-weighted and has sufficient strength, owing to a change in a plate thickness of its portion optimum for strength improvement. In an under-run protector which includes a hollow material having a rectangular cross section and mounted on a vehicle body frame via a mounting bracket, a plate thickness of a substantially horizontal surfaces forming the hollow material on a vehicle body frame side with respect to a longitudinal-direction center line of the hollow material is larger than a plate thickness of a substantially horizontal surfaces opposite the vehicle body frame with respect to the longitudinal-direction center line of the hollow material.