**3. Methodology**

To evaluate energy supply security, different analytical approaches and indicators, such as energy resource reserves [19], cost of energy security [23], energy dependence [6], energy diversity [6,7,10,11,19], and energy market concentration [33] have been presented in the literature. Amongst them, energy dependence and diversity have been regarded as the two main paradigms for evaluating energy supply security [6]. This study applied these two indicators and proposed modified indices of energy diversity to quantitatively assess the energy supply security of Korea, a country highly dependent on energy imports.
