Samsung Techwin Co., Samsung Group\'s defense and precision machinery unit, said Tuesday that its third-quarter net profit dropped 42 percent from one year ago mainly due to weak demand and higher raw material costs. Net profit reached 41.4 billion won (US$36.8 million) in the July-September period, compared with 70.8 billion won a year earlier, it said in a regulatory filing. Sales fell 14 percent on-year to 693.5 billion won over the cited period and operating profit also plummeted 60 percent to 34.8 billion won, it said. The weak third-quarter bottom line took a blow from weak demand for personal computers and flat-screen TVs, the company said. Costs of silver, copper and other raw materials also rose sharply, eating into its profit. Electronics firms slashed down their investments as they anticipate the global economy potentially slowing down. The reduced spending squeezed Samsung\'s revenues from semiconductor equipment, it added.