Abstract: A noise reducing apparatus for a cyclo-fan is provided for the canceling of a whistling noise with a specific frequency, determined by the product of the rotation number of the cyclo-fan and the number of blades thereof. The apparatus comprises a cyclo-fan including a plurality of blades with arc shapes radially disposed centering the axis thereof, and a couple of supporting members for supporting both ends of the respective blade; a sensor for the passage of the respective blade at a fixed position; a controller for calculating the frequency and pressure level of a peculiar noise generated by the cyclo-fan based on the signal transmitted from the sensor, and then generating an electric signal corresponding to the interference sound having a reverse phase and same pressure level to that the peculiar noise, and a plurality of speakers for converting the electric signal from the controller into the interference sound.

Abstract: The present invention relates to a pool where a false floor is horizontally arranged and a plurality of longitudinal grooves are installed within the inside-walls of a pool, and lifting units are equipped in each longitudinal grooves to lift a false floor. A lifting apparatus installs a pair of shafts of rotation movement at the top and bottom of a pillar body which is installed within each longitudinal grooves, places a sprocket and a pulley in juxtaposition to each shafts of rotation movement to freely rotate, suspends a chain on a pair of sprockets, suspends a wirerope on a pair of pulleys, fixes the chain and the wirerope to the arm of a false floor which is projected toward the longitudinal groove, rotates a driving sprocket by a motor to drive the chain which is engaged thereto, thereby lifting the false floor, and vertically moves the wirerope in accordance with a lifting of the false floor and fixes it by a wirerope fixing element to maintain a false floor during the stop of it.