Hey Woong!
As far as I know, you need to deploy your app to a server in order for it to work with Shopify. This allows your shop to conserve its available storage space, as well as prevent any catastrophes from happening in the event of buggy apps or any other thing that can possibly go wrong ;)
We suggest using Heroku.com to store your apps. We use it quite a bit as well.
Have a good one!
Matthew Buttler
Guru
Shopify Inc.