For South Korea as a whole, that seems as much a prophecy as an ambition. Like Japan in the 1960s, the country is poised for an assault on the world’s export markets. Its surging $81 billion economy is churning out a flood of increasingly sophisticated products, from shoes, toys and telephones to video recorders and microprocessors. Korea’s mighty conglomerates dominate Middle East construction, and they command key shares of the world’s shipbuilding, textile and steel industries.