Participants sing the South Korean national anthem in unison at a square of the Kim Koo Museum and Library in Seoul on April 11, 2021, during a national ceremony to mark the 102nd anniversary of th

This photo taken April 9, 2021, shows South Korea's first prototype of the next-generation KF-X fighter, officially dubbed KF-21 Boramae, being revealed at the Korea Aerospace Industries Co.

This photo, provided by Seoul's foreign ministry, shows the MT Hankuk Chemi, a South Korean oil tanker, departing the Iranian port of Rajai on April 9, 2021 (Korean time), as it was released along

An election official shows a voting stamp with which voters mark their ballots while installing a polling station in Seoul on April 6, 2021, the eve of the Seoul mayoral by-election. (Yonhap)

People who were forced to leave or flee North Korea hold a traditional rite at a public cemetery in the southwestern city of Gwangju on April 5, 2021, to pay tribute to their ancestors, marking the

Fans take in a Korea Baseball Organization regular season game between the home team Doosan Bears and the Kia Tigers at Jamsil Baseball Stadium in Seoul on April 4, 2021. (Yonhap)
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Kids plant saplings in a field in the southeastern city of Daegu on April 2, 2021, on the occasion of Arbor Day that will come on April 5. (Yonhap)
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A voter wearing sanitary gloves casts a ballot at a polling station in Seoul on the first day of two-day early voting for the April 7 Seoul mayoral by-election on April 2, 2021. (Yonhap)

A visitor enjoys the 13th Gwangju Biennale in Gwangju, 330 kilometers south of Seoul, on April 1, 2021, after it was opened to the public.

This photo, released by the state-run Korea Minting, Security Printing & ID Card Operating Corp.