Abstract: An unmanned aerial comprises: a motor and a propeller assembly connected to the motor comprising: a first structure fixed to the motor, having a cylindrical wall defining an inner space, with a helical slit formed through the cylindrical wall; a second structure comprising a cylinder portion, a part of which is rotatably positioned in the inner space, and at least one protruding portion protruding from the outer surface of the cylinder portion to the outside of the cylindrical wall through the helical slit; and a propeller comprising a cylindrical hub engaging with the cylinder portion of the first structure, rotating blades extending from the cylindrical hub, and at least one rib extending from the cylindrical hub toward the motor, the propeller being configured such that at least a part of the rib detachably engages with the first structure by the at least one protruding portion of the second structure.

Abstract: An unmanned aerial vehicle is provided. The unmanned aerial vehicle includes a housing with a first housing structure and a second housing structure, a wireless communication circuit coupled to the housing or located inside the housing for wireless communication with an external controller, a plurality of propulsions systems coupled to the housing, and a navigation circuit configured to control the plurality of propulsion systems. At least one of the plurality of propulsion systems includes a plurality of folding arms pivotally coupled to one of the first housing structure and the second housing structure, a motor controlled by the navigation circuit, and a propeller coupled to the motor. The housing has at least one recess to accommodate at least part of the plurality of propulsion systems in the second state.

Abstract: An unmanned aerial vehicle according to various embodiments includes: a housing; a communication circuit, wherein the communication circuit establishes wireless communication with an external controller; and a plurality of propulsion systems connected to the housing, wherein the propulsion systems include: a motor; a rotation shaft having an axis extending in a first direction, wherein a first end is connected to the motor, and wherein the rotation shaft is rotates in a first direction by the motor; a cap structure fixed to the second end of the rotation shaft, a propeller including: a hub including a through-hole formed in the first direction, such that the rotation shaft rotatably passes through the through-hole, wherein the propeller is detachably connected to the cap structure, such that, when an external force is exerted on the blade, the propeller is released from the cap structure to be freely movable along the axis toward the motor.

Abstract: An unmanned aerial vehicle includes a housing, a wireless communication circuit, a navigation circuit, a plurality of propulsion systems, and a propeller. At least one of the plurality of propulsion systems includes a motor, and a construction disposed to the motor. The construction includes a first side, a second side facing the motor in a direction opposite to the first side, a shaft inserting hole disposed to the second side, and a latching protrusion and a latching groove that are extended sequentially inside the shaft inserting hole. The propeller is fastened to the construction, and includes a hub coupled to the first side of the construction, a fixing shaft that protrudes in a direction of the construction that is inserted to the shaft inserting hole of the construction, and at least one protrusion on an outer circumferential surface of the fixing shaft.

Abstract: An unmanned aerial vehicle according to various embodiments of the present disclosure comprises: a housing; a wireless communication circuit connected to the housing or positioned in the housing and configured to connect wireless communication with an external controller; a plurality of propulsion systems connected to the housing or at least partially contained in the housing; and a navigation circuit configured to control the plurality of propulsion systems. At least one of the plurality of propulsion systems comprise a motor controlled by the navigation circuit and a propeller assembly connected to the motor.

Abstract: An unmanned aerial vehicle is disclosed. The unmanned aerial vehicle includes a housing, a wireless communication circuit, a navigation circuit, a plurality of propulsion systems, and a propeller. At least one of the plurality of propulsion systems includes a motor, and a construction disposed to the motor. The construction includes a first side, a second side facing the motor in a direction opposite to the first side, a shaft inserting hole disposed to the second side, and a latching protrusion and a latching groove that are extended sequentially inside the shaft inserting hole. The propeller is fastened to the construction, and includes a hub coupled to the first side of the construction, a fixing shaft that protrudes in a direction of the construction that is inserted to the shaft inserting hole of the construction, and at least one protrusion on an outer circumferential surface of the fixing shaft.

Abstract: An unmanned aerial vehicle is provided. The unmanned aerial vehicle includes a housing with a first housing structure and a second housing structure, a wireless communication circuit coupled to the housing or located inside the housing for wireless communication with an external controller, a plurality of propulsions systems coupled to the housing, and a navigation circuit configured to control the plurality of propulsion systems. At least one of the plurality of propulsion systems includes a plurality of folding arms pivotally coupled to one of the first housing structure and the second housing structure, a motor controlled by the navigation circuit, and a propeller coupled to the motor. The housing has at least one recess to accommodate at least part of the plurality of propulsion systems in the second state.

Abstract: An unmanned aerial vehicle according to various embodiments includes: a housing; a communication circuit, wherein the communication circuit establishes wireless communication with an external controller; and a plurality of propulsion systems connected to the housing, wherein the propulsion systems include: a motor; a rotation shaft having an axis extending in a first direction, wherein a first end is connected to the motor, and wherein the rotation shaft is rotates in a first direction by the motor; a cap structure fixed to the second end of the rotation shaft, a propeller including: a hub including a through-hole formed in the first direction, such that the rotation shaft rotatably passes through the through-hole, wherein the propeller is detachably connected to the cap structure, such that, when an external force is exerted on the blade, the propeller is released from the cap structure to be freely movable along the axis toward the motor.

Abstract: A hydraulic brake device and a method for controlling the same are disclosed. The disclosed hydraulic brake device determines failure of a booster pressure sensor provided at a hydraulic power unit, using pressure correlation among a master cylinder pressure sensor, a pressure sensor provided at the hydraulic power unit to detect a pressure transferred to a hydraulic pressure controller, and a high pressure accumulator pressure sensor. When there is failure of the booster pressure sensor, the driver is informed of the failure, and a braking operation is carried out, taking into consideration the failure. Accordingly, it may be possible to avoid excessive braking, sudden braking, insufficient braking, etc., and to achieve enhancement in braking sensation and braking force.

Abstract: A high strength cold-rolled steel sheet, which simultaneously provides a tensile strength of 70 to 90 kgf/mm2 grade and is easily formed, thereby increasing an impact energy absorption in case of collision and enhancing the safety of automobiles, and its manufacturing method. The high strength cold-rolled steel sheet with excellent formability and weldability, comprises, in percent by weight, 0.15 to 0.25% C, 0.5 to 1.5% Si, 1.0 to 2.0% Mn, 0.25% or less P, 0.020% or less S, 0.015 to 0.050% Al, 0.008 to 0.026% N, balance Fe and incidental impurities while satisfying a condition of 1.2≦Si[%]+50/8P[%]≦2.0. The method comprises the steps of hot rolling a steel having the above composition, cold rolling the hot-rolled steel sheet to form a cold-rolled steel sheet; continuous annealing the cold-rolled steel sheet at a temperature range satisfying a condition of 563+651C[%]+42 Si[%]+18Mn[%]≦annealing temperature [° C.