1. Frequent Users of Hospital Emergency Departments in Korea Characterized by Claims Data from the National Health Insurance: A Cross Sectional Study Woo, Jung Hoon; Grinspan, Zachary; Shapiro, Jason; Rhee, Sang Youl 2016 Articles Multivariate analysis--Data processingHospitals--Emergency services--UtilizationEmergency medical services--EvaluationMedicinePublic policy (Law)Health services administrationMedical care