Evaluate the Safety and Immunogenicity After MG1111(BARICELA Inj.) as 2nd Vaccination in 4 ~ 6 Year Old Healthy Children With a History of 1st Varicella Vaccination

* Primary objective is to assess the safety of MG1111 until Day 42 using as 2nd vaccination * Secondary objective to assess the immunogenicity and safety of MG1111 using as 2nd vaccination

1. Safety * Incidence of fever (temperature ≥39.0℃) within 42 days after the IP administration * Incidence of fever (temperature ≥39.0℃) within 7 days after the IP administration * Solicited local/systemic AEs occurred within 7 days after the IP administration * Unsolicited adverse events that occurred within 42 days after the IP administration * Serious adverse events that occurred within 1 year after the IP administration * Vital signs and physical examinations 2. Efficacy (Immunogenicity) -GMT(Geometric Mean Titer) and GMR(Geometric Mean Ratio(fold change))measured by the glycoprotein enzyme-linked immunosorbent assay (gpELISA) at before and 42 days after the IP administration 3. Exploratory assessment * GMV and GMR of VZV-CMI response measured by INF-r ELISPOT at before and 42 days after the IP administration * GMT and GMR of the antibody titer measured by gpELISA at before and after the IP administration for 3 years * Varicella-like rash and Varicella-zoster virus genotyping analysis occurred after IP administration for 3 years