SEOUL, South Korea — By many measures, South Korea’s health care system is among the most successful in the world. Seeing a doctor is easy. The mortality rate from preventable illnesses is low.

And though most hospitals and clinics are privately run, a nationalized single-payer health insurance program keeps costs affordable. An appendectomy costs $2,500 — less than a fifth of the average price in the United States — with 80% of that covered by government insurance. But a four-month-old strike by more than 9,000 medical residents and interns across the country is turning the public against the medical establishment.

At issue is a government plan to add 1,497 slots to medical school admissions — a 48% increase — in order to meet the rising need for health care as South Korea’s population ages . The government says it is simply trying to plug shortages in essential fields such as pediatrics or gynecology, which doctors are increasingly shunning for higher-paying specializations. But junior doctors, backed by their senior peers, say that a wave of new graduates will compromise the quality of medical education, lead to unnecessary medical appointments and drive down physician salaries.

“Of course we are conscious of the fact that these new graduates will end up joining the competition in the private practice market later,” said Dr. Peter Han, a 30-year-old internal medicine resident who resigned from his job at a major teaching hospital in Seoul in February. “.