To expect to see something as probable, likely or reasonable -When you expect something it is like you are mentally assuming that it will happen. You expect the sun to rise in the morning because it has happened everyday of your life so far. You also expect to get paid for the work that you do because it is reasonable. Imagine that you are still waiting for the bus. You expect it to come at 5pm because that is the schedule and it has come at that time for the last month. To look forward to thinking about something in the future, with pleasure -When you look forward to something, it is a combined sense or feeling of hoping, expecting and waiting regarding something pleasurable in the future. For example I am looking forward to going to Canada this summer.

"I've expected to see him" means you knew he would come. "I've been looking forward to seeing him" means you really want to see him, but you don't know for sure if you will. Both 'expect' and 'look forward to' are used with something that might happen in the future. ***But both words play a different meaning when used in a sentence. Like UlyanaP wrote that 'expect' is to believe or assume(you have some sort of real information to back up your idea) and 'to look forward to' is to hope (usually out of feeling). ^-^

expect just implies that you think or predict that something will happen. i don't think it has any positive or negative feeling. ex. i expect a lot of people will come to the party. in your example, 'i didn't expect him to come', it does not imply that you were looking forward to seeing him. it just means that you simply thought he would not come. i think the confusion is that 'expect' is translated as 기대. instead of 그 친구가 오기를 기대했어요, it might be more appropriate to translate it as, 그 친구가 올 줄 알았어요.