Abstract: The present invention provides a method for preparing metallic lithium by electrolysis using a non-aqueous electrolyte at low temperature. The method for preparing metallic lithium according to the present invention can directly prepare metallic lithium by electrolysis at a low temperature, and enable mass production, and reduce the manufacturing cost due to its simple process and easy control of electrolytic conditions, and thus the method for preparing lithium thin films according to the present invention can be applied in the industry.

Abstract: An ultrasonic contact transducer for point-focussing surface waves having a narrow beam width and a high sound intensity at a focal point in order to obtain better resolution and high beam intensity, which is applicable to the nondestructive testing technique of the surface or subsurface of a specimen to be tested, is disclosed. The ultrasonic contract transducer generates surface waves, focuses the waves at one point on the surface of the specimen and receives again the signals scattered from the surface flaws or subsurface flaws of the specimen, in order to detect the surface cracks, surface flaws, subsurface flaws of the specimen and to detect the delamination in a thin laminated film.