Abstract: A node group management device includes a communication interface managing a first group, to which some nodes belong among nodes that constitute a blockchain network sharing a distributed database, a memory that stores information related to a node of the first group (including a public key of each node of the first group), and a processor connected to the memory. All nodes participating in the blockchain network each include a private key and a public key. The processor operates according to instructions stored in the memory and generates a group private key allowing a transaction to be additionally signed based on said information while the transaction is signed with the private key when the node of the first group generates the transaction and configured to distribute the group private key to the first group so that the nodes of the first group hold the group private key in common.

Abstract: A distributed network includes a plurality of computing devices operably connected to each other over a network and a server. The plurality of computing devices include a first gateway, a distributed database implemented with at least some of the plurality of computing devices over a network, a first memory including a group device list that stores information associated with computing devices included in a first group managed by the first gateway, and a first processor operably connected to the distributed database and the first memory, and a network interface configured to communicate with the distributed network. The server includes a second memory configured to store a gateway list including information associated with a plurality of gateways including the first gateway and a second processor.

Abstract: A content sharing and creation server according to an embodiment performs, generating project identification information based on a first user's project start request for generating content, generating a first smart contract on regulations for issuing a token based on the project start request, generating a second smart contract on regulations for transferring the token to an account of a second user when the second user transfers a cryptocurrency to a pre-designated contract account, an operation for generating a third smart contract on regulations for transferring the cryptocurrency held in the contract account from the contract account to an account of the first user based on a pre-designated amount or ratio so that the first user receives the cryptocurrency when a transfer execution transaction occurs, and determining the occurrence of the transfer execution transaction based on evaluation information evaluated by the second user regarding the progress of the project.

Abstract: Disclosed are a system for and a method of providing wireless multimedia services using Bluetooth. The system includes at least one Bluetooth terminal having an embedded Bluetooth chip able to transfer data, a converter establishing a Bluetooth network with the Bluetooth terminal, the converter being connected with a wired network, and serving to convert data used in the Bluetooth network and the wired network, and a gateway linked to the converter and adapted to perform a conversion between the data converted by the converter and an Internet packet. In accordance with the present invention, it is possible to not only inexpensively provide domestic multimedia mobile communication services between Bluetooth terminals, but also inexpensively use international multimedia services conventionally incurring a considerable charge.