Abstract: Disclosed is an electrically-driven scalp massager in which the procedure of massaging the scalp of a person to promote the circulation of blood while strengthening the root of hair to reduce and prevent hair loss is conveniently carried out in accordance with a simple manipulation, so that the scalp massager provides a convenience in use while being conveniently portable.

Abstract: Disclosed is an electric fan including a driving motor, a blower fan unit, and front and rear safety nets. A far infrared ray lamp part including a socket and a far infrared ray lamp is positioned in front of the blower fan unit. The front and rear safety nets are detachably fastened to each other by a fastening ring. A lamp protective net, which is covered with a stainless coating to be decreased in heat conductivity and heat-resistant, is placed in front of the far infrared ray lamp part where heat is generated.

Abstract: A semiconductor memory device including an operation control circuit for selecting between a single data rate (SDR) mode and a double data rate (DDR) mode. The operation control circuit includes a mode selector for generating a master signal which selects between the SDR and the DDR mode. The operation control circuit also includes a shift register, a repeater, and a pulse generator. When the SDR mode is selected, the shift register generates an output clock signal which changes states every period of the input clock signal. When the DDR mode is selected, the repeater generates an output clock signal which changes states with every state change of the input clock signal. Productivity efficiency is enhanced and production costs are reduced by providing both the SDR and the DDR mode circuitry and the operation control circuit on a single chip.