[1] Pukyong Natl Univ, Dept Phys, Pusan 608737, South Korea
[2] Pukyong Natl Univ, Div Econ, Pusan 608737, South Korea
[3] Korea Adv Inst Sci & Technol, Dept Phys, Taejon 305701, South Korea
[4] Pukyong Natl Univ, Dept Environm Atmospher Sci, Pusan 608737, South Korea
[5] E Piedmont Univ, Dept Adv Sci & Technol, I-15100 Alessandria, Italy