Abstract: According to the present invention, a ladder having an adjustable length comprises: a first support including a first outer support and a first inner support inserted into the first outer support; a horizontal foothold for connecting the first supports to each other; a first gear formed at the inner side of the horizontal foothold and having a groove part formed therein; a second gear engaging with the first gear and changing the rotational direction of the first gear; a rotary bar coupled to the second gear; a third gear formed at the end of one side of the rotary bar; a screw bolt having a fourth gear, which engages with the third gear and is formed at the end thereof, formed inside the first inner support, formed in a stick type, and having threads formed on the outer side thereof; and a screw nut in which the screw bolt is formed, and to which the first inner support is coupled at the outer side thereof.

Abstract: Provided is a congestion control method for controlling message flooding between nodes in response to situation information in information centric network environment with delay tolerant networking, and a recording medium and a device for performing the same. The congestion control method includes, when a first node contacts a second node, exchanging information associated with stored messages with the second node, identifying whether an anti-flag is stored in the first node, the anti-flag being assigned when each message arrives at a destination node, flooding of a non-anti-flagged message among the messages stored in the first node to the second node, and flooding of an anti-flagged message among the messages stored in the first node to the second node according to at least one of situation information including a hop count, a Time-To-Live (TTL) and a number of requester nodes of the corresponding message and a mobility of the first node, or restricting the flooding to the second node.

Abstract: Provided is a congestion control method for controlling message flooding between nodes in response to situation information in information centric network environment with delay tolerant networking, and a recording medium and a device for performing the same. The congestion control method includes, when a first node contacts a second node, exchanging information associated with stored messages with the second node, identifying whether an anti-flag is stored in the first node, the anti-flag being assigned when each message arrives at a destination node, flooding of a non-anti-flagged message among the messages stored in the first node to the second node, and flooding of an anti-flagged message among the messages stored in the first node to the second node according to at least one of situation information including a hop count, a Time-To-Live (TTL) and a number of requester nodes of the corresponding message and a mobility of the first node, or restricting the flooding to the second node.

Abstract: According to the present invention, a ladder having an adjustable length comprises: a first support including a first outer support and a first inner support inserted into the first outer support; a horizontal foothold for connecting the first supports to each other; a first gear formed at the inner side of the horizontal foothold and having a groove part formed therein; a second gear engaging with the first gear and changing the rotational direction of the first gear; a rotary bar coupled to the second gear; a third gear formed at the end of one side of the rotary bar; a screw bolt having a fourth gear, which engages with the third gear and is formed at the end thereof, formed inside the first inner support, formed in a stick type, and having threads formed on the outer side thereof; and a screw nut in which the screw bolt is formed, and to which the first inner support is coupled at the outer side thereof.