Abstract: An example unmanned aerial vehicle includes a housing; a wireless communication module; a plurality of propulsion systems; and a navigation circuit. At least one of the plurality of propulsion systems includes a motor; and a propeller assembly rotatably connected to the motor. The propeller assembly comprises: a hub structure including a surface facing away from the motor; a first connecting member including a first post and a second post extending in parallel to and spaced apart from the first post, and the first post and the second post are fixed to the surface and are able to move elastically in a second direction perpendicular to the first direction; a first blade detachably coupled to the first connecting member and comprising an opening to which the first post and the second post are coupled; and a cap detachably coupled to the top of the first connecting member.

Abstract: A propeller control system of an air mobility is configured to insert a movable part forming a propeller into a fixed part in a situation where the air mobility is stored and crashes, thereby reducing an entire length of the propeller. As a result, an entire size of the air mobility is reduced when the air mobility is stored, which may prevent secondary accidents caused by fragments generated by contact of the rotated propeller with the ground in the situation where the air mobility crashes.

Abstract: The present invention relates to a negative electrode including a current collector and a negative electrode active material layer disposed on the current collector, wherein the negative electrode active material layer includes a negative electrode active material, carbon black, and a binder, wherein the negative electrode active material includes silicon particles, and the binder includes a copolymer containing a unit derived from a poly(vinylalcohol) (PVA) and a unit derived from an ionized and substituted acrylate, the binder being included in the negative electrode active material layer in an amount of 18 wt % to 22 wt %.

Abstract: Disclosed is a composite negative electrode active material comprising silicon-based core particles, an outer carbon coating layer present on the silicon-based core particles, and single-walled carbon nanotubes, wherein the single-walled carbon nanotubes are in contact with the outer carbon coating layer and comprise a body partially spaced apart from the outer carbon coating layer, and the outer carbon coating layer comprises oxygen in an amount of 35 wt % to 55 wt % therein.

Abstract: The present application provides a method for preparing a composite material. The present application provides a method for preparing a composite material comprising a metal porous body and a polymer component, wherein the polymer component is formed in an asymmetrical structure, and a composite material prepared in such a manner.

Abstract: This application relates to a device and a method for calculating a fault ratio. The method may include by using image frames collected from a camera of a first vehicle, generating a driving route in which the first vehicle travels, and acquiring fault information of a traffic accident involving a second vehicle, the traffic accident being related to the driving route of the first vehicle. The method may also include changing factors related to braking or steering of the first vehicle and the second vehicle, and generating multiple simulation driving scenarios by simulating the driving route on the basis of the changed factors. The method may further include computing a fault ratio of the first vehicle and the second vehicle for each of the multiple simulation driving scenarios by correcting the fault information on the basis of the factors.

Abstract: A method for manufacturing a secondary battery including: forming an electrode assembly including a negative electrode including a silicon-based active material, a positive electrode facing the negative electrode, and a separator between the negative electrode and the positive electrode; impregnating the electrode assembly by injecting an electrolytic solution into the electrode assembly to form an impregnated electrode assembly; performing activation through first charging/discharging in at least one cycle while pressurizing the impregnated electrode assembly to form an activated electrode assembly; allowing the activated electrode assembly to stand at 40° C. to 80° C. in a state of being charged to a SOC of 70% or more; removing a gas generated from the electrode assembly after allowing the activated electrode assembly to stand; and subjecting the electrode assembly to a second charging/discharging in at least one cycle at 15° C. to 30° C. after the removing of gas generated from the electrode assembly.

Abstract: A propeller safety device is provided. The propeller safety device is configured to insert a moving part of a propeller into a fixed part during a crash of an air mobility to allow a reduction in the total length of the propeller, thereby preventing the propeller from hitting the ground. Accordingly, a secondary accident due to fragments formed when the rotating propeller hits the ground is prevented.

Abstract: The present invention provides a battery system including one or more secondary batteries each including a negative electrode including a silicon-based active material, a positive electrode facing the negative electrode, a separator interposed between the negative electrode and the positive electrode, and an electrolyte and a control unit configured to set a driving voltage range for charging and discharging of the secondary batteries, wherein a maximum driving voltage of the secondary battery set by the control unit is in a range of 4.00 V to 4.08 V, and a minimum driving voltage of the secondary battery set by the control unit is in a range of 2.98 V to 3.07 V.

Abstract: The present application provides a method for manufacturing a metal foam. The present application can provide a method for manufacturing a metal foam, which is capable of forming a metal foam comprising uniformly formed pores and having excellent mechanical properties as well as the desired porosity, and a metal foam having the above characteristics. In addition, the present application can provide a method capable of forming a metal foam in which the above-mentioned physical properties are ensured, while being in the form of a thin film or sheet, within a fast process time, and such a metal foam.

Abstract: The present invention relates to a method of manufacturing a secondary battery comprising the steps of: forming a secondary battery structure comprising an electrode assembly comprising a negative electrode, a positive electrode, and a separator and an electrolyte solution, and activating the secondary battery structure by charging and discharging for at least one cycle while pressing the secondary battery structure at 1.5 MPa to 3.5 MPa, wherein the negative electrode comprises a silicon-based active material.

Abstract: The present invention provides a negative electrode which comprises: a negative electrode current collector; and a negative electrode active material layer formed on the negative electrode current collector and comprising a negative electrode active material containing a silicon-based active material and a carbon-based active material, a binder, and single-walled carbon nanotube aggregates. The single-walled carbon nanotube aggregates are comprised at 0.05 parts by weight to 0.37 parts by weight based on 100 parts by weight of the silicon-based active material in the negative electrode active material layer.

Abstract: A refrigerator and a method for controlling the same. The refrigerator includes a main body; a first storage chamber and a second storage chamber provided in the main body; a first evaporator provided in the first storage chamber, configured to generate cool air; a second evaporator provided in the second storage chamber, configured to generate the cool air; a switching valve configured to supply a refrigerant to at least one of the first evaporator or the second evaporator; and a controller configured to generate a control signal for controlling the switching valve so that the refrigerant supplied to at least one of the first evaporator or the second evaporator is distributed according to a predetermined reference, and lower the temperature of the first storage chamber and the second storage chamber to a predetermined temperature based on the generated control signal.

Abstract: The present disclosure relates to a heat-radiating mechanism for an antenna device, and particularly, includes: a plurality of communication elements generating predetermined heat upon electrical operation, a heat-radiating combined case having the plurality of communication elements accommodated in one surface thereof and a plurality of heat-radiating ribs integrally formed on the other surface thereof, and an antenna board mounted with the plurality of communication elements on one surface of the heat-radiating combined case, in which the plurality of heat-radiating ribs are formed such that the rising airflow formed by being heat-radiated from the relatively lower portion of the heat-radiating combined case is exhausted to be inclined upward to the left and right outsides of the heat-radiating combined case in the width direction from the relatively upper position, thereby improving the heat-radiating performance of the antenna device.

Abstract: Methods for manufacturing a composite material and composite materials are provided. The method may include preparing a metal foam, preparing a mixture including the metal foam and a curable polymer, curing the curable polymer of the mixture to obtain a composite material, and performing a planarization treatment. The planarization treatment may be performed on the metal foam before preparing the mixture, on the mixture before curing the curable polymer, and/or on the composite material. The composite materials may include a metal foam and a polymer that is on a surface and/or in pores of the metal foam. The composite material may have a surface roughness of 2 ?m or less and/or may have a thermal resistance of 0.5 Kin2/W or less at 20 psi.

Abstract: A negative electrode for a lithium secondary battery having excellent dispersibility, adhesion and tensile strength, and a lithium secondary battery including the same. The negative electrode for a lithium secondary battery includes negative electrode active material particles, a conductive material and a binder. The binder includes a copolymer comprising acrylamide monomer-derived repeating units, acrylic acid monomer-derived repeating units, sodium acrylate monomer-derived repeating units and acrylonitrile monomer-derived repeating units. The combined weight of the acrylic acid monomer-derived repeating units and sodium acrylate monomer-derived repeating units in the copolymer is 25 wt % to 35 wt %. The negative electrode active material particles are silicon-based negative electrode active material particles.

Abstract: Disclosed is a negative electrode which includes: a negative electrode current collector; and a negative electrode active material layer on the negative electrode current collector. The negative electrode active material layer includes a silicon-based negative electrode active material, a binder, a conductive material, and single-walled carbon nanotubes. The single-walled carbon nanotubes are present in an amount of 0.001 wt % to 1 wt % in the negative electrode active material layer.

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: Provided herein are methods of preparing a metal foam that include the steps of forming a metal foam precursor with a slurry comprising a metal component, a dispersant, a binder and an antisolvent, and sintering the metal foam precursor. Such methods may provide metal foams having various pore sizes. Methods further include forming a thin metal foam on a base material.

Abstract: An image forming device and an operating method of an image forming device are provided. The operating method includes receiving first authentication information of a first user with respect to the image forming device, authenticating the first authentication information of the first user, based on reference account information of a plurality of users, the reference account information being stored in a storage based on a blockchain that distributes and manages a ledger in which user account information including authentication information and authority information of a user with respect to a certain image forming device has been recorded, when the authentication of the first user is completed, receiving a request to perform a first image forming job, and evaluating first authority information indicating an authority range of the first user, based on the reference account information of the plurality of users, and performing the first image forming job within the authority range of the first user.