South Korean conglomerate Hanwha Group on Monday raised its offer for the remaining stake it does not already own in Singapore's Dyna-Mac, valuing the offshore oil and gas contractor at S$790.6 million ($605.41 million).The improved offer of S$0.67 per share represents a 35.4% premium to Dyna-Mac's last traded price on Sept. 10, before Hanwha's earlier offer of S$0.60 per share was disclosed.