CREATE TABLE table_204_174 (id DECIMAL, "rank" DECIMAL, "name" TEXT, "nationality" TEXT, "result" DECIMAL, "notes" TEXT)

which person medaled , but was not from south korea ?
SELECT "name" FROM table_204_174 WHERE "rank" IS NULL AND "nationality" <> 'south korea'
SELECT "name" FROM "table_204_174" WHERE "nationality" <> 'south korea' AND "rank" IS NULL