Is it safe for a lady to travel without companion in Korea,especially in the big cities?

Its quite safe in Korea, but its does mean korea have no crime, maybe petty crime.

In South Korea? Yes, of course. No problem. Koreans are very helpful and friendly. They are honest and trustworthy. Very hospitable. Been there twice.

as in any big city, there will always be shady areas to avoid. stick to the main, busy streets and you should be fine. korea (seoul in particular) is generally safe, compared to other asian countries.

wait- you do mean south korea, right? ;-)

Of course! There are many lights turned on along the street.

Yes. Pretty much.

Seoul, yes.

I've been to Seoul twice by myself and I never had any problems. Many areas are well lit and there always seemed to be people out on the streets.

Very well safe, Safer than USA

usually