thanks for advice!
as Brynner said, i put custom aura files in same folder with original aura files
but, aura didnt change...
in my grf,
texture\effect\aurafloat.tga
texture\effect\auraring.bmp
these files are same folder in,
texture\effect\ring_blue.tga
texture\effect\pikapika2.bmp
it seems that I tried the same way that I found by searching......
EDIT:
when i renamed custom aura to official name, custom aura was displayed correctly...
I've been confused....