title: Modification of the gravity model and application to the metropolitan Seoul subway system.
abstract: The Metropolitan Seoul Subway system is examined through the use of the gravity model. Exponents describing the power-law dependence on the time distance between stations are obtained, which reveals a universality for subway lines of the same topology. In the short (time) distance regime the number of passengers between stations does not grow with the decrease in the distance, thus deviating from the power-law behavior. It is found that such reduction in passengers is well described by the Hill function. Further, temporal fluctuations in the passenger flow data, fitted to the gravity model modified by the Hill function, are analyzed to reveal the Yule-type nature inherent in the structure of Seoul.
authors.affiliation: Department of Physics and Astronomy and Center for Theoretical Physics, Seoul National University, Seoul, Korea.
authors.forename: Segun
authors.initials: S
authors.lastname: Goh
authors.forename: Keumsook
authors.initials: K
authors.lastname: Lee
authors.forename: Jong Soo
authors.initials: JS
authors.lastname: Park
authors.forename: M Y
authors.initials: MY
authors.lastname: Choi
mesh_terms: D000465:Algorithms; D002947:Cities; D006112:Gravitation; D006801:Humans; D007723:Korea; D015233:Models, Statistical; D009068:Movement; D010825:Physics / Q000379:methods; D011890:Railroads; D012944:Social Support; D012984:Software; D013997:Time Factors; D014186:Transportation