WordPress interal server error with utf-8 encoded url ?

How are you ? Please give your advice !

FACT:
why is this url not working ?
https://www.ekdkr.com/itblog/archives/tag/%ed%95%9c%ea%b8%80

However, the url which is made of just English, not foreign language, works fine! : https://www.ekdkr.com/itblog/archives/tag/vlc

Recently I realized that my wordpress “www.ekdkr.com/itblog” has a issue about regarding utf-8 encoded url.

First, I was suspicious about server’s setting.(I purchased startlogic.com) But, server supports utf-8 url, because the following address works just fine!:
https://www.ekdkr.com/%ED%85%8C%EC%8A%A4%ED%8A%B8.html

Then, I checked my database, and php.ini setting.
All the setting were set to use utf-8.

What makes this internal error ?
Please help me !