South Korea’s economy grew sharply in the second quarter, expanding at its fastest rate in a year, fueled by strong output of semiconductors, ships and automobiles, the Bank of Korea said. Gross domestic product expanded 4.9 percent in the three months ended June 30 from the second quarter last year, the central bank said. That was up from the 4 percent rate in the first quarter and the highest since growth of 5.1 percent in the second quarter last year. Compared with the previous quarter, the economy grew 1.7 percent. The manufacturing sector grew 3.6 percent in the second quarter, rebounding from a contraction of 0.9 percent in the first quarter. South Korea’s exports grew 5.2 percent, up from the first quarter’s 2.7 percent expansion.