Abstract: A repair method for a structure having an open flaw in a welding heat affected portion, including, removing at least a part of the open flaw and thereby forming a concave portion in the welding heat affected portion, forming build-up weld layers so as to fill the concave portion, treating a surface of the build-up layers to reduce tensile residual stress by means of at least one of laser peening, shot blasting and water jet machining. Also disclosed is an apparatus suitable for carrying out the repair method.

Abstract: An engaging force of a pump impeller (1a) connected to an engine (21) and a turbine runner (1b) connected to an automatic transmission (23) is controlled by a controller (5). The controller (5) determines a target relative rotation speed of the pump impeller (1a) and the turbine runner (1b), and performs feedback control of the engaging force such that the difference between the target relative rotation speed and the real relative rotation speed is decreased. The controller (5) also performs feedforward control of the engaging force in a increasing direction. When the engine (21) is in a predetermined engine-stall prevention condition, the controller (5) prohibits the feedforward control so as to prevent an interference between feedback control and feedforward control.