Abstract: In the case of a gas in which several gases are mixed, a type and concentration of the gas may be incorrectly measured when measured using only an optical band-pass filter. The invention of the present application is directed to providing a technology in which a plurality of broadband band-pass filters having overlapping regions are provided to calculate a magnitude of absorption for each wavelength band for light passing through each broadband band-pass filter, thereby identifying the presence of a gas of interest and the presence of a gas other than the gas of interest.

Abstract: The present invention relates to a security system for accessing a private network service in a communication network and a method thereof, in which if a request of a subscriber for accessing a private network service is sensed, layer 2 tunnel protocol (L2TP) requests the virtual private network service access to a remote authentication dial-in user service server, and according to the request for accessing the private network service, the remote authentication dial-in user service server transfers layer 2 tunnel protocol (L2TP) information on layer 2 tunnel protocol (L2TP) network connected to the virtual private network, and pre-designated secret information in the layer 2 tunnel protocol (L2TP) network server to the layer 2 tunnel protocol (L2TP) access concentrator, and finally, after receiving the information on layer 2 tunnel protocol (L2TP) network and the secret information, the layer 2 tunnel protocol (L2TP) access concentrator performs encryption on the data generated by the subscriber by using the