Well, it depends, but I think "부산 가는 기차" will make perfect sense with three different tenses. 부산 가는 기차+예요.(O) 부산 가는 기차+였어요(O) 부산 가는 기차+일 거예요(O), not the future tense, just guess. Both ..갈../..간..기차 has limited usages because we usually say "부산 가는 기차(a train which is supposed to head for Pusan)". When we talking about timetable or route of public transportation, usually the present tense is used like in English. \^o^/

Yes. 1. 부산 가는 기차 (present - a train that is going to Busan right now.) 2. 부산 간 기차 (past - a train, that went to Busan.) 3. 부산 갈 가차 (future - a train, that will go to Busan.) Another Example: 1. 어제 만난 친구가 연락했어요. (The friend I met yesterday called.) 2. 처음에 만나는 친구와 무슨 이야기할까요? (What will I talk about with someone (a friend) I meet the first time?) 3. 내일 만날 친구는 작년에 중국여자랑 결혼했어요. (The friend I'll meet tomorrow married a Chinese girl last year.)