The present invention discloses a novel 6-fluoro-1,4-dihydro-7-4–1-piperazinyl-4-oxoquinoline-3-carboxylic acid derivatives, with a process for their preparation, and with pharmaceutical compositions containing them as the active ingredient for the treatment of bacterial infections andor renal cancer diseases. The coupling system may serve as a detachable interface between an individual engaged to the robotic device. Light emission can be reversibly and repeatedly cycled on and off by sweeping the potential between two values. According to the embodiments herein, load balancing can be implemented when an MVNO and an MNO share a network resource. The present invention also relates to novel cationic lipids. As a result, it is possible to control a necessary supply of hydrogen and a recirculation flow rate by selecting an area of a nozzle throat in the fuel cell system using the ejector, and specifically, of being automatically controlled to supply hydrogen through a small nozzle at a low load, such that a recirculation amount is increased.