CORNING, N.Y., June 12 -- Corning Inc. will cut more than 600 jobs as it scales back its Corning Cable Systems operations in North and South America and restructures a plant in North Carolina. The cuts are part of Corning's previously announced plan to eliminate about 4,000 employees, or 12.5 percent of its global work force, to reduce costs. The latest cuts will occur in the Corning Cable Systems unit and through the restructuring of its Optical Assembly Plant in Hickory, N.C. Including the previously announced closing of a facility in Puerto Rico, the Corning Cable Systems unit will have shed 10 percent of its work force in North and South America. The unit is also developing a plan to reorganize its European facilities. Final decisions will be announced in the next several weeks, the company said.