Park, K.-S., S.-H. An, H. Kim, C.-H. Joh, and W. Suh. “Spatial Analysis of Subway Ridership: Rainfall and Ridership”. Proceedings of Engineering and Technology Innovation, vol. 4, Oct. 2016, pp. 1-3, https://ojs.imeti.org/index.php/PETI/article/view/241.