South Korea reported one of the first major coronavirus outbreaks outside China, yet has kept infections low compared with the U.S. WSJ’s Dasl Yoon shows how smartphones have become one of the country’s most effective weapons against the pandemic. Photo: Denis Bosnic for The Wall Street Journal South Korea fell into a recession in the second quarter as the coronavirus pandemic took a heavy toll on the export-reliant country, which recorded its worst performance since 1998 when it was embroiled in the Asian financial crisis. Gross domestic product shrank 3.3% between April and June from the previous quarter, following a quarter-on-quarter contraction of 1.3% for the months of January to March, Bank of Korea data showed Thursday. …