Give in has the sense of surrender or as you say yield and is usually used without an object, in which case it becomes give into. An example: After a considerable period of questioning by the police the accused gave in and admitted that he had committed the murder.
Give up suggests no longer doing something/stop doing something as in: The accused gave up claiming that he had been in another place when the murder took place.
Haihao … There are subtle shades of difference and I wish I could construct a hard and fast ‘rule’ for you to use, but I can’t think of one. This seems to be a case where you just have to get familiar with the various ways the two expressions are used.
For instance… If one was frustrated with a task and quit, one would be more likely to say “I give up!” rather than “I give in!” but if you did use the latter it wouldn’t sound unduly unusual. However, one always ‘gives in’ to temptation rather than ‘gives up’ to it…
I guess I got it by ‘its spirit’ this time and am very much satisfied. Thank you so very much for your patient interpretation, Pond (may I call you like that?)