Metrication in the United States There are no U.S. customary units for electric current, potential difference, or charge since these concepts were developed after the international adoption of metric in science. The metric units ampere, volt, ohm and coulomb are the only units used. The SI term hertz has replaced the term "cycles per second" as a unit of frequency. Energy is often measured in watt hours, BTUs, therms or calories rather than the SI joule. Residential and commercial electrical energy use is metered and billed in kilowatt hours, kW·h, as in most metric countries. Force measurements regularly use the pound instead of the SI
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