Abstract: Disclosed is a pH-sensitive block copolymer obtained by copolymerization of: (a) a polyethylene glycol compound (A); and (b) at least one poly(amino acid) compound selected from the group consisting of a poly(?-amino ester) and poly(amido amine) or a copolymer thereof (B). A method for preparing the same block copolymer, and a polymer micelle type drug composition comprising the pH-sensitive block copolymer and a physiologically active substance that can be encapsulated with the block copolymer are also disclosed. The pH-sensitive block copolymer is obtained by polymerization of a hydrophilic polyethylene glycol compound with a pH-sensitive biodegradable poly(amino acid) compound. Therefore, the pH-sensitive block copolymer can form a micelle structure due to its amphiphilicity and ionization characteristics depending on pH variations, and thus can be used as drug carrier for target-directed drug delivery depending on pH variations in the body.

Abstract: An access pointer for interconnecting a power line communication (PLC) network of a home network and a wireless network and a method therefor are provided. When data is received from the PLC network through media access control of a data link layer, data on upper layers above a network layer in the received data is converted into a format suitable to a wireless network layer. The converted data is transmitted to the wireless network through the media access control of the data link layer. Accordingly, the PLC network and the wireless network are easily interconnected.

Abstract: Provided is a method of securely transferring a programmable packet using digital signatures having an access-controlled high-security verification key, by which the programmable packet is transferred using digital signatures having a sufficiently long signing key and an access-controlled high-security verification key in an environment of a programmable network that only a transfer node knows an address of a final receipt node and intermediate receipt nodes are not determined.