On the back, there is a model number.
Cf. https://www.ifixit.com/Teardown/iMac%2BIntel%2B27-Inch%2BEMC%2B2309%2Band%2B2374%2BTeardown/1236

With that model number, I found a control board for the panel which is being sold in Amazon.
https://www.amazon.com/gp/product/B01F5I8HHE/ref=oh_aui_detailpage_o00_s00?ie=UTF8&psc=1
The price is about 60천원. Delivery took 14 days.

Adapter of DC 19V 4.7A (15천원) and mini Displayport to Displayport cable (5천원) from Compuzone.
I am planning to connect mac mini 2009 to the display.
The frame will be reused, too.

total price: about 80천원

The controller board did not work at first.
It is different from the picture of Amazon.
But after several triasl of reconnection, it is working now.
The V-sync cable that is attached to the panel for the LED backlight sync, is not necessary.
It is said to be integrated to DisplayPort cable after 2011 (?).