UPDATE 2-POSCO ups steel prices by 16-18 pct -ind. sources

* Hot-rolled, cold-rolled, plate prices to rise by 160,000 won/T * First rise since June to be effective for orders from April 22 * Higher hikes than mkt expected; weak global demand weigh on * Shares gain 0.32 pct in a broader market down 1 pct (Recast...