Researchers of Kim Il Sung University have developed in a Korean way an advanced heat treatment technology badly needed in the machine-building industry. It is also called a two-frequency induction heating method which uses medium-frequency and high-frequency current at the same time in one inductor. The new technology makes it possible to produce high-quality gears with ordinary carbon steel, without using expensive alloy steel materials. It is in the limelight of many officials and experts as it can improve the quality of gears and other machine parts.