Oct 20 South Korean steelmaker POSCO said its third-quarter operating profit crept up 0.5 percent from a year earlier, beating estimates, as more stable iron ore input costs helped it absorb weak steel product prices and a continuing supply glut. POSCO, the world's sixth-biggest steelmaker, said on Tuesday operating profit for July-September was 638 billion won on a parent-only basis, above a consensus forecast of 608 billion won compiled by Thomson Reuters I/B/E/S.