Authors’ contributions
Study conception/design: Min Hur, Jin-Tae KimData acquisition/analysis/interpretation: Hyun-Kyu Yoon, Min Hur, Dong Hyuk Kim, Ja Hyeon KuDrafting of paper: Hyun-Kyu Yoon, Min Hur, Jin-Tae KimRevising of paper critically for important intellectual content: Hyun-Kyu Yoon, Jin-Tae KimFinal approval of paper: all authors.