that have flights to Jeju are Daegu, Busan, Gunsan and Gwangju. Jeju is also accessible from Busan by ferry. The travel time is between 3 and 12 hours. The island has a public bus system, but there are no railways on the island. A rail tunnel to the island, linking it to the Korea Train Express network has been proposed but is currently on hold due to cost concerns and local opposition in Jeju, who are aware of an eventual loss of their indigenous traits. Cheju/Jeju Naval Base In 1993 the Republic of Korea (ROK) began planning a naval base on Jeju Island. Construction started in Gangjeong village in 2007, with planned completion by 2011. The base was designed to be a mixed military-commercial port similar to those in Sydney and Hawaii, that could accommodate 20 warships and three submarines, as well as two civilian cruise ships displacing up to 150,000 tons. Its official name is the Jeju Civilian-Military Complex Port. Jeju residents, environmentalists, and opposition parties opposed the construction claiming that environmental hazards will damage the "Island of Peace" designated as such by the government. The protests caused delays in the construction. The base was completed in 2016. Health In 2002, scarlet fever was reported to be in Korean children in Jeju Province. Scientists have been doing research on the matter by creating an age-period-cohort (APC) analysis to back up their relevant hypotheses regarding this emerging outbreak. The Korean National Health Insurance Service analyzed this data from the nationwide insurance claims. Their calculations of the crude incidence rate (CIR) and applying the intrinsic estimator (IE) for age and calendar groups revealed that a total of 2,345 cases of children had the fever that was one of the top illnesses. It also led to the discovery that children aged 0–2 were the most common victims of the fever and that it was mostly boys rather than girls that carried it. The CIR decreased with age between 2002 and 2016 and the age period effect decreased in all observed years. The IE coefficients validating a cohort effect went from negative to positive in 2009. To this day, no one can explain how these children in Jeju Province had scarlet fever, but results suggest that it might be explained through the cohort effect. Further descriptive epidemiological studies are needed to test children that are born after 2009, to determine whether they have