Issac Koga

Issac (Issaku) Koga was born on December 5, 1899 in Tashiro Village (now Tosu) in Saga Prefecture, Japan, the eldest of 7 children. In July 1920, at the age of 20 he started to study at the Department of Electrical Engineering of Tokyo Imperial University (later renamed University of Tokyo). After graduation in August 1925, he moved to the new Tokyo City Electrical Institute, which was established to develop and promote radio broadcasting technology under the directorship of Kujirai Kotaro, a pioneer of research and teaching of radio science. Initially an engineer, he became an assistant professor in 1929. Under the guidance of Prof. Kotaro he studied crystal oscillators, forming the basis of his PhD thesis, completed in April 1930, entitled "Characteristics of the crystal oscillator". This work included making the first quartz tuning forks in 1927. In 1944 he became a professor of the University of Tokyo, later a professor emeritus with the same University.[1][2]

As well as observing how the piezoelectric oscillations of the quartz crystal depended on its shape and cut, he theoretically analyzed their behavior.[3] He developed many applications of crystal oscillators, in particular a crystal (the “Koga cut”) oscillator which was stable to temperature variations [4] with applications in wireless communications and time keeping, forming basis of the Japanese Quartz clock and watch industry.[5] He was awarded the Japan Academy Prize in 1948 (the citation reads for "Theoretical and Experimental Investigation upon the Fundamental Characteristics of Piezoelectric Oscillating Crystal and Quartz Crystal Oscillator Circuit and Their Applications to Wireless Communication and Crystal Clock"),[6] the Order of Cultural Merit award in 1963 and became a member of the Japanese Academy in 1971. He served as president of the International Union of Radio Science (URSI) between 1963 and 1968.[7]

Koga died on September 2, 1982. In his honor, the International Union of Radio Science, URSI, named a young scientist award after him (the Issac Koga Gold Medal [8]) first awarded in 1984 and subsequently awarded every 3 years.

References

  1. ↑ http://www2.iee.or.jp/ver2/honbu/30-foundation/data02/ishi-04/ishi-0607.pdf Japanese text describing Koga's life and work.
  2. ↑ http://www.civic.ninohe.iwate.jp/100W/09/088/ Japanese text describing Koga's career
  3. ↑ Koga, I., M. Aruga, Y. Yoshinaka, Theory of Plane Elastic Waves in a Piezoelectric Crystalline Medium and Determination of Elastic and Piezoelectric Constants of Quartz, Phys. Rev. March 1958, Volume 109, pp 1467-1473, doi: 10.1103/PhysRev.109.1467
  4. ↑ Koga, I. Notes on Piezoelectric Quartz Crystals, Proceedings of the Institute of Radio Engineers, March 1936, Volume 24, Issue 3, pp 510-531, doi: 10.1109/JRPROC.1936.226840.
  5. ↑ Brief chronology of the development of quartz clocks and watches listing Koga's major contributions
  6. ↑ Citation for Koga's 1948 Japan Academy Prize
  7. ↑ The list of Presidents of URSI
  8. ↑ The URSI Issac Koga Gold medal