What year did Bangkok University and Chunnam Dragons have a score of 0-0?
CREATE TABLE "results" (
  "season" real,
  "team_1" text,
  "score" text,
  "team_2" text,
  "venue" text
);
SELECT SUM("season") FROM "results" WHERE "team_1"='bangkok university' AND "score"='0-0' AND "team_2"='chunnam dragons';