Abstract: An encryption key management method includes: receiving a data registration request from a supplier terminal, determining a data identifier associated with the content data, encrypting a master key with a public key of the supplier terminal, and providing the supplier terminal with the master key encrypted with the public key of the supplier terminal, the data identifier, and a key update count value; receiving a subscription application related to the data identifier from a first subscriber terminal, encrypting the master key with a public key of the first subscriber terminal, and providing the first subscriber terminal with the master key encrypted with the public key of the first subscriber terminal and the key update count value; receiving encrypted content data encrypted with the symmetric key and a hash for the content data from the supplier terminal; and transmitting the encrypted content data and the hash to the first subscriber terminal.

Abstract: Provided is a method for generating a one class model based on a data frequency. The method for generating a one class model based on a data frequency includes: generating, by a machine learning apparatus, a plurality of spatial coordinates by arranging a plurality of learning data in corresponding coordinates in a feature space; classifying, by the machine learning apparatus, the plurality of spatial coordinates into a plurality of internal coordinates PI and a plurality of external coordinates PO based on a frequency of the learning data arranged in the respective spatial coordinates which belong to the plurality of spatial coordinates; and generating, by the machine learning apparatus, a one class model based on the plurality of internal coordinates PI based on mutual spatial distances of the plurality of external coordinates PO and the plurality of internal coordinates PI.

Abstract: The present invention relates to a sensor for sensing hydrogen. The sensor of the present invention comprises: a core which reacts with hydrogen to change a resistance value; at least two electrodes connected to the core; and a variable resistor which is connected to at least one of the two electrodes and of which the resistance value changes in response to a control signal, wherein the core includes palladium having a thin film shape, and graphene which is applied on the palladium and has a thin film shape.

Abstract: Provided is a method for generating a one class model based on a data frequency. The method for generating a one class model based on a data frequency includes: generating, by a machine learning apparatus, a plurality of spatial coordinates by arranging a plurality of learning data in corresponding coordinates in a feature space; classifying, by the machine learning apparatus, the plurality of spatial coordinates into a plurality of internal coordinates PI and a plurality of external coordinates PO based on a frequency of the learning data arranged in the respective spatial coordinates which belong to the plurality of spatial coordinates; and generating, by the machine learning apparatus, a one class model based on the plurality of internal coordinates PI based on mutual spatial distances of the plurality of external coordinates PO and the plurality of internal coordinates PI.

Abstract: The present invention relates to a sensor for sensing hydrogen. The sensor of the present invention comprises: a core which reacts with hydrogen to change a resistance value; at least two electrodes connected to the core; and a variable resistor which is connected to at least one of the two electrodes and of which the resistance value changes in response to a control signal, wherein the core includes palladium having a thin film shape, and graphene which is applied on the palladium and has a thin film shape.