SEOUL, May 9 — South Korean President Yoon Suk-yeol said today his government’s efforts to improve people’s lives had fallen short, conceding a crushing election defeat for his ruling party last month reflected voters’ assessment of his two years in office.

In his first news conference in 21 months, Yoon pledged to focus on improving the economy and tackling what he called the national emergency of flagging birth rates over the three years he has left in office.