SI base unit referenced to the values of the fundamental constants, namely the Planck constant ("h"), the electron charge ("e"), the Boltzmann constant ("k"), and the Avogadro constant ("N"). This approach was approved in 2018, only after measurements of these constants were achieved with sufficient accuracy. SI base unit The International System of Units (SI) defines seven units of measure as a basic set from which all other SI units can be derived. The SI base units and their physical quantities are the meter for measurement of length, the kilogram for mass, the second for time, the ampere for electric current, the kelvin
Lee Si-Chen Lee Si-Chen Lee Si-Chen (; born August 13, 1952 in Gangshan (岡山), Taiwan), is a Taiwanese engineer specializing in semiconductors, a researcher in amorphous silicon in the early development in Taiwan, and an IEEE Fellow. He has been a professor of electrical engineering since 1982 and the president of National Taiwan University from 2005 to 2013. He received a bachelor's degree in electrical engineering from National Taiwan University (1974) and a master's degree (1977) and PhD (1981), both in electrical engineering, from Stanford University. He is the current president of National Taiwan University (2005 – ), president of the Association