A top executive of the Korean conglomerate that’s buying a Philadelphia shipyard pledged to bring the facility back its 1940s prominence. “We will be investing in Philly big time,” said Michael Smith, the newly named chief executive officer of Hanwha Defense USA. The yard is primarily known now for building Jones Act ships. U.S. law requires ships engaged in domestic maritime trade to be built in the United States. The yard produces about 50 percent of the largest domestically-built commercial vessels, including tankers and container ships, according to the company. Speaking at a Hudson Institute event on the defense industrial