Linux Apache PHP Oracle客户端 - >返回问号而不是韩文文本

Summary: When using PHP oci8 to get Korean text from oracle server deployed on another machine, question marks displayed rather than Korean chars.

I've tried following steps:

1. Environment: Linux Redhat6, Sqlplus, Apache2, PHP5.4, Oracle 11g instant client.
2. When using sqlplus, connected to the remote Oracle server, Korean texts can be shown correctly.
3. When querying select * from V$NLS_PARAMETERS Where PARAMETER='NLS_LANGUAGE' ==> KOREAN.
4. In /etc/init.d/httpd file, I've add export NLS_LANGUAGE=KOREAN and restarted Apache. Still doesn't work.