The captain of the USS Dubuque is refusing to appear at a Navy disciplinary hearing on charges of dereliction of duty for failing to rescue a boatload of Vietnamese refugees who claim they later resorted to cannibalism to survive, the service says. Capt. Alexander G. Ba-lian, 48, of Los Angeles has been charged with two counts of violating lawful orders under a section of the Uniform Code of Military Justice that calls for "non-judicial punishment proceedings," said Cmdr. David Dillon, a Pacific Fleet spokesman in San Diego, Calif. He was ordered to appear at a closed "admiral's mast" Wednesday before Vice Adm. George W. Davis Jr., the head of all surface ships in the Pacific Fleet, the spokesman added. But Balian notified the Navy on Tuesday that he was exercising his right to refuse the admiral's mast.