In the study of networks, such as complex network, social network or biological network; number of different characteristics of many nodes are found common. These characteristics includes small-world property, clustering and community structure, among others. In the context of networks, community structure refers to occurrence of groups of nodes in a network that are more densely connected internally, then with the rest of network. This heterogeneity of connection suggests that network has certain natural division within it. Being able to identify their sub-structure within the network can provide inside into how network function and topology affects each others.