Network flow optimization analyzes optimization problems on networks; hence, network optimization is reflected in many application fields including transportation, telecommunication, computer networking, financial planning, logistics and supply chain management, energy systems, etc. However, to date, most network optimization problems that have been studied are static network optimization problems. But "real world networks" are time-varying in essence, and therefore any flow within a network must take a certain amount of time to traverse an arc. Moreover, the parameters of "real world networks" may change over time. Problems such as how to plan and control the transmission of flow becomes very important, because waiting at a node, or traveling along a particular arc with different speed, may allow one to catch the best timing along the path; thus, achieving the objective and changing the decision making process. It should be noted that there are a host of decision making problems in practice that should be formulated as optimization models on time-varying networks.