Abstract: The present invention relates to a positive electrode active material and a lithium secondary battery including the same, and more particularly, to a positive electrode active material including an overlithiated lithium manganese-based oxide, which is able to prevent the degradation of the electrochemical properties of a lithium secondary battery, including rate characteristics, caused by an excess of lithium and manganese in the lithium manganese-based oxide by inducing the growth of primary particles constituting the lithium manganese-based oxide, and prevent the lifetime deterioration of a lithium secondary battery by reducing side reactions between the lithium manganese-based oxide and a liquid electrolyte particularly during high-voltage operation, and at the same time, inhibiting or mitigating the release of a transition metal from the lithium manganese-based oxide, and a lithium secondary battery including the same.

Abstract: The present invention relates to a positive electrode active material and a lithium secondary battery including the same, and more particularly, to a bimodal-type positive electrode active material which is capable of improving the low energy density per unit volume of an overlithiated lithium manganese-based oxide, preventing the degradation of electrochemical properties of a lithium secondary battery, including rate characteristics, caused by an excess of lithium and manganese in the lithium manganese-based oxide, and particularly preventing the lifetime deterioration of a lithium secondary battery by inhibiting or mitigating the release of a transition metal from the lithium manganese-based oxide, and a lithium secondary battery including the same.

Abstract: The present invention relates to a positive electrode active material and a lithium secondary battery including the same, and more particularly, to a bimodal-type positive electrode active material for improving the low energy density per unit volume of an overlithiated lithium manganese-based oxide and a lithium secondary battery including the same.

Abstract: The present invention relates to a positive electrode active material and a lithium secondary battery including the same, and more particularly, to a positive electrode active material including an overlithiated lithium manganese-based oxide, and capable of preventing the degradation of electrochemical properties of a lithium secondary battery, including rate characteristics, caused by an excess of lithium and manganese in the lithium manganese-based oxide and reducing side reactions between the lithium manganese-based oxide and a liquid electrolyte during high-voltage operation through induction of the growth of primary particles constituting the lithium manganese-based oxide.

Abstract: An audio-visual system may include a housing comprising an open upper end and a storage space, an audio-visual device installed inside the housing and exposable through the open upper end, and a lifting device configured to expose or store the audio-visual device inside the housing through the open upper end. The audio-visual device may include a display, a speaker, and a processor configured to control the audio-visual system to operate in a first mode for outputting media art content while the display is stored in the housing according to a first event, operate in a second mode for outputting audio content through the speaker while part of the display is exposed through the open upper end according to a second event, and operate in a third mode for outputting a visual content while the entire display is exposed through the open upper end according to a third event.

Abstract: Disclosed are a method and an apparatus for an instant messaging service to provide a schedule service. A schedule management server according to an example embodiment includes receiving a schedule creating request, selecting any one of a first type of calendar belonging to a chatroom in which the schedule creating request is created and a second type of calendar belonging to a user account which creates the schedule creating request, according to a schedule type included in the schedule creating request; and creating a schedule corresponding to the selected type of calendar.

Abstract: Disclosed are a method and an apparatus for an instant messaging service to provide a schedule service. A schedule management server according to an example embodiment includes receiving a schedule creating request, selecting any one of a first type of calendar belonging to a chatroom in which the schedule creating request is created and a second type of calendar belonging to a user account which creates the schedule creating request, according to a schedule type included in the schedule creating request; and creating a schedule corresponding to the selected type of calendar.

Abstract: Disclosed are a method and an apparatus for an instant messaging service to provide a schedule service. A schedule management server according to an example embodiment includes receiving a schedule creating request, selecting any one of a first type of calendar belonging to a chatroom in which the schedule creating request is created and a second type of calendar belonging to a user account which creates the schedule creating request, according to a schedule type included in the schedule creating request; and creating a schedule corresponding to the selected type of calendar.

Abstract: Disclosed are a method and an apparatus for an instant messaging service to provide a schedule service. A schedule management server according to an example embodiment includes receiving a schedule creating request, selecting any one of a first type of calendar belonging to a chatroom in which the schedule creating request is created and a second type of calendar belonging to a user account which creates the schedule creating request, according to a schedule type included in the schedule creating request; and creating a schedule corresponding to the selected type of calendar.

Abstract: An operation method for an instant messenger server is provided. The method includes generating a schedule which depends on an account of a host in response to a schedule generation request of the host, determining invitees based on at least one of a chat room list and a friend list of the account of the host, synchronizing schedules which depend on accounts of users who participate in the schedule, based on whether at least one guest included in the invitees participates, and providing a notification of the schedule to at least one of the users who participate in the schedule, through a user interface (UI) of a chat room provided through the instant messaging service.

Abstract: An operation method for an instant messenger server is provided. The method includes generating a schedule which depends on an account of a host in response to a schedule generation request of the host, determining invitees based on at least one of a chat room list and a friend list of the account of the host, synchronizing schedules which depend on accounts of users who participate in the schedule, based on whether at least one guest included in the invitees participates, and providing a notification of the schedule to at least one of the users who participate in the schedule, through a user interface (UI) of a chat room provided through the instant messaging service.