Abstract: Disclosed are novel compounds of Chemical Formula 1, optical isomers of the compounds, and pharmaceutically acceptable salts of the compounds or the optical isomers. The compounds, isomers, and salts exhibit excellent activity as GLP-1 receptor agonists. In particular, they, as GLP-1 receptor agonists, exhibit excellent glucose tolerance, thus having a great potential to be used as therapeutic agents for metabolic diseases. Moreover, they exhibit excellent pharmacological safety for cardiovascular systems.

Abstract: Provided is a probing method for handoff including constructing a group of neighbor access points of a current access point with which the station associated, generating subgroups of the neighbor access points by the channel assigned to the access points, probing the access points by subgroup in a subgroup selection order, and selecting the neighbor access point having best link quality as a target access point to handoff. The probing method of the present invention is implemented with a novel non-overlap graph for constructing the neighbor graph such that the probing latency is dramatically reduced, resulting in reduction of handoff delay.