Korea Institute of Geoscience and Mineral Resources

Samsung Electronics Co., Ltd.

Ho-sung Yoon

Kyeong-Woo Chung

Chul-Joo Kim

Doo-young Kim

Provided is a memory device including a delay circuit having gate insulation films with thicknesses different from each other. The memory device includes a delay circuit configured to input an input signal and output an output signal, and circuit blocks configured to control an operation of reading or writing memory cell data in response to the input signal or the output signal. One of transistors constituting a circuit block has a gate insulation film having such a thickness that an effect of negative biased temperature instability (NBTI) or positive biased temperature instability (PBTI) on the transistors is minimized. The delay circuit may be affected little by a shift in a threshold voltage that may be caused by NTBI or PBTI, and thus, achieve target delay time.

Memory device including delay circuit having gate insulation films with thicknesses different from each other

Disclosed is a method of recovering a rare earth element from oxidized scrap of permanent magnet. The method includes leaching an oxidized scrap of a permanent magnet from a sulfuric acid solution, and recovering the rare earth element after precipitating the rare earth element contained in the oxidized scrap of the permanent magnet by adding sodium sulfate into the sulfuric acid solution.

Method of recovering rare earth elements from oxidized scrap of permanent magnet

Disclosed herein is a uranium ion exchange adsorption method using ultrasound. The method includes placing a slurry obtained by mixing uranium ions, sulfuric acid and an ion exchange resin into a reaction bath, and stirring the slurry in the reaction bath while simultaneously applying ultrasound to the reaction bath to allow the uranium ions to be adsorbed to the ion exchange resin through ion exchange adsorption. The method has an improved ion exchange adsorption rate of the uranium ions.

Uranium ion exchange adsorption method using ultrasound

A highly efficient uranium leaching method using ultrasound is disclosed. The uranium leaching method includes preparing black slate powder containing uranium by pulverizing black slate containing uranium, placing the black slate powder and water in a reaction bath, and performing uranium leaching by adding and mixing sulfuric acid and an oxidant with the black slate powder and water to prepare a mixture in the reaction bath while applying ultrasound to the reaction bath. In this method, uranium leaching efficiency can be maximized by adding sulfuric acid to the uranium ore while applying ultrasound thereto.

Growing community of inventors

Seoul, South Korea

Ho-sung Yoon