KorailTalk is a mobile ticket booking application from Korea Railroad Corporation. As one of the most widely used applications released by a public corporation in Korea, we have put significant thought into overall UX design to improve usability and address any inconveniences for existing users. We not only improved the ticket reservation and confirmation process, but also considered universal usability by applying suitable font sizes and colors, taking into account social minorities, color vision-deficient individuals, and foreigners. HNINE took the lead in the overall UX planning and design, as well as Android app development.