* KOSPI rises, foreigners net buyers * Korean won strengthens against dollar * South Korea benchmark bond yield falls * For the midday report, please click SEOUL, Oct 27 (Reuters) - Round-up of South Korean financial markets: ** South Korean shares closed more than 3% higher on Tuesday, as chipmakers jumped on a rally in US AI stocks and robust domestic GDP data. ** The benchmark KOSPI closed up 168.87 points, or 3.09%, at 5,638.34, after rising as much as 4.9% during the session.