Authors’ contributions
D.H.S., D.K., J.C., and G.Y.G.: study design, D.K. and H.K.: data collection and statistical analysis, D.H.S. and D.K.: drafting of the manuscript, Y.P., Y.S.H., J.C., and G.Y.G.: critical review of the manuscript. J.C., and G.Y.G.: study supervision. All the authors have full access to all of the data and take responsibility for the integrity of the data and the accuracy of the data analysis.