I use part of south korea flag (the taegukgi circle) as an icon, i treat this to have look like a splash shape that represent spirit, passion, kindness, warmth and movement. I think it can reflect a seoul city nowday. Inside the icon i hide S letter in negative space as a unique point, also the icon of logo can be a pattern itself, it can be help when the logo will be applied at branding activity. 🙂