[1] Kangwon Natl Univ, Dept Chem Engn, Samcheok 245711, Gangwon Do, South Korea
[2] Kyung Hee Univ, Dept Chem Engn, Yongin 446701, Gyeonggi Do, South Korea
[3] Korea Gas Corp R&D Ctr, DME Project Team, Inchon 406103, South Korea
[4] Korea Gas Corp R&D Ctr, DME Project Team, Inchon 406130, South Korea