Abstract: A fluid level measurement system using a buoyant body includes a guide part installed in a direction perpendicular to the bottom surface of a fluid storage tank, and provided with a space in which a fluid can move therein; a buoyant body inserted into the guide part, and configured to float along the surface of the fluid inside the guide part; and a measurement part coupled to the top end of the guide part, and configured to measure the level of the surface of the fluid inside the fluid storage tank by transmitting a signal toward the buoyant body in the inner space of the guide part and then receiving a signal reflected from the buoyant body.

Abstract: Embodiments of the present disclosure provide an active terminal detection method and an active terminal detection device that increase the performance of determining whether a terminal is active by designing a spread code to reduce a cross-correlation value of the spread code of a terminal with a high activation frequency in a massive machine-type communication environment by using deep learning.

Abstract: A hammer bit includes a bit body coupled to a hammer drill, a housing bit disposed to the bit body, at least one wing bit coupled to the housing bit to move up and down slantly, and having a rotating radius that is more increased than an outer surface of the bit body when moving up and is more decreased than the outer surface of the bit body when moving down, and at least one spacer installed to move up and down together with the wing bit and filling up an upper space of the wing bit when the wing bit moves down.

Abstract: A hammer bit includes a bit body coupled to a hammer drill, a housing bit disposed to the bit body, at least one wing bit coupled to the housing bit to move up and down slantly, and having a rotating radius that is more increased than an outer surface of the bit body when moving up and is more decreased than the outer surface of the bit body when moving down, and at least one spacer installed to move up and down together with the wing bit and filling up an upper space of the wing bit when the wing bit moves down.