Do all KEB branches accept Foreign Direct Investment Notification (FDI)?
No, they don't. There are the KEB branches designated for Foreign Direct Investment Notification. Here is the list of branches that you can go on with FDI Notification Procedures.
Regional Notification accepting branches
Seoul 1) Headquarters International Corporate Div. 02) 729 - 0285
    3th Floor, 181, 2Ka, EULJI-RO, CHUNG-KU, SEOUL, KOREA
2) World Trade Center Br. 02) 551 - 7950 159, ASEM TOWER,
    SAMSEUNG-DONG, GANGNAM-GU, SEOUL
Busan Busan Br. 051) 463 - 1681
89-1, JUNG-ANG-DONG 4-GA, JUNG-GU, BUSAN
Daegu Daegu Br. 053) 253 - 5242
58-7, POJUNG-DONG, JUNG-GU, DAE-GU
Deajeon Daejeon Br. 042) 252 - 7800
195-1, DAEHEUNG-DONG, JUNG-GU, DAEJEON
Incheon Incheon Br. 032) 763 - 7001
18-8, SINPO-DONG, JUNG-GU, INCHEON
Kwangju Kwangju Br. 062) 222 - 4111
1-2, GEUMNAMRO1-GA, DONG-GU, GWANGJU
Suwon Suwon Br. 031) 232 - 9111
763-8, INGYE-DONG, PALDAL-GU, SUWON-CITY, GYEONGGI-DO
Jeonju Jeonju Br. 063) 288 - 8111
52, GOSA-DONG 1-GA, JEONJU, JEOLLABUK-DO
Cheongju Cheongju Br. 043) 252 -3211
47-2, SEOWUN-DONG, SANGDANG-GU, CHEOUNGJU, CHUNGCHEONGBUK-DO
Cheonan Cheonan Br. 041) 563 - 6930
107-1, ORYONG-DONG, CHEONAN, CHUNGCHEONGNAM-DO
Ulsan Ulsan Br. 052) 272 - 6146
583-6, SINJEONG3-DONG, NAM-GU, ULSAN
Chuncheon Chuncheon Br. 033) 252 - 2407
655, HYOJA 2-DONG, CHUNCHEON-CITY, GANGWON-DO
Jeju Jeju Br. 064) 757 - 2171
1430-9, 1DONG, IL-DO, JEJU, JEJU-DO