Abstract: An antenna apparatus includes: a parabolic reflector; a dielectric support pedestal; a sub-reflector connected to an upper part of the dielectric support pedestal; and a waveguide connected to a lower part of the dielectric support pedestal, wherein the parabolic reflector has a curved surface in which a ratio of a focal length to a diameter is greater than a preset value, and at least one corrugation configured to suppress a cross polarization is formed in a region of the dielectric support pedestal.

Abstract: The present invention relates to a high voltage-type redox flow battery comprising: a plurality of modules (1001, 1002, 1003, . . , 100n) which are serially connected; and a battery management system (BMS) for monitoring a state-of-charge (SOC) of each of the plurality of modules (1001, 1002, 1003, ..

Abstract: A method for a first user terminal to use a messenger service of a group chat room is proposed. The method may include receiving, from a server, invitation information associated with a second user's inviting a first user to the group chat room, and displaying chat room information on the group chat room. The method may also include in response to the second user not being registered as a friend of the first user in the messenger service, displaying information on the second user and an interface for deciding whether to participate in the group chat room. The method may further include acquiring an interaction regarding a decision to participate in the group chat room through the interface, and displaying a message created in the group chat room.