Should I send reminder to a professor in a school I applied to, for an introduction email I sent two weeks ago?

As a busy professor myself, I personally appreciate getting a reminder email. I fully intend to reply to every email I get from a prospective student, even if only to say "Sorry, your research interests do not seem to be a good match for the work we are doing in my group." But in practice, life gets busy. I'm traveling. Or I'm booked solid with meetings and so I don't have time to immediate answer the 50 or so daily emails requiring responses. And so some emails fall through the cracks. Thus I appreciate receiving a single reminder email. Such emails help me do something I want to do: namely, be the kind of person who gives every serious inquiry the courtesy of a response. (A second reminder email is not necessary. If I haven't replied the first two times, there is likely a reason.)

As for what to write, anything short and sweet and non-accusatory should be fine. Personally, I prefer the polite fiction that perhaps I did not receive the original email. You know it's not true, I know you know it's not true, but in phrasing your note this way we agree to mutually overlook these facts. I'd suggest something very simple, such as the following.

Dear Prof. X,

I wrote you a letter a few weeks ago, but given the uncertainties of email I do not know whether you received it. Thus I am resending my note just in case.

With my best regards, Joe

[and then append the earlier letter here]

Generally speaking, I would recommend that you don't.

I think it is perfectly fine to send such an e-mail in the first place, but you should remember that these professors don't owe you a response. Admissions (at least in the US, in mathematics -- I would guess CS is the same) are typically handled by a committee, and many professors might prefer to wait until the committee has decided whom to admit before trying to recruit prospective graduate students.

However, you might send similar e-mails to other professors in the same departments. At least in my field, it is a good idea to study at a department where there are several professors with whom you would interact scientifically.

In the fall, such e-mails are more likely to get a response, since professors are trying to encourage strong students to apply. As it is now, since you have applied already, I would recommend waiting for an official response and following up if you are accepted.