As Shin Hyun Song takes the helm of the Bank of Korea this week, the seasoned economist is taking on an ambitious task: making the won a global currency without jolting capital flows, just as Asia's fourth-largest economy enters a turbulent phase.

Shin, 66, is best known internationally for warning of the 2008 global financial crisis well before it hit. Now he is proposing to "rebuild a framework" that could unwind ?a protective fortress around the won ¡ª a system he helped design himself when he last served in Seoul as a presidential adviser in 2010.

"Even China is struggling to ?internationalise the ?yuan. So realistically it would be a challenging goal," said Chang Jaechul, an economist at Pinnacle Economic Research Institute.