Table: korean_surnames
Columns: hangul
hanja
revised
mccune_reischauer
estimated_distribution_2000

Question: Tell me the revised of mccune reischauer of yŏn (s) ryŏn (n)
SQL: SELECT "revised" FROM korean_surnames WHERE "mccune_reischauer" = 'yŏn (s) ryŏn (n)'

Question: Name the hanja for hangul of 주
SQL: SELECT "hanja" FROM korean_surnames WHERE "hangul" = '주'

Question: Tell me the hanja of eum
SQL: SELECT "hanja" FROM korean_surnames WHERE "revised" = 'eum'