ѱ ڿ Ǿ(Robert Willard Pierce) ƿ ε 1950, ̱ Ʋ忡 繫 , Ѱ Բ ѱ ȣȰ ߽ϴ.
ϳ ϴ ͵ ϼҼ Ǿ 70 ݵ ҿܵ ̵ ̾ ֽϴ.
, 糭 ȣ 弹ϴ. ʾ, ٴٿ ǥϴ Ʈ ε鿡 ʷ (Seasweep) °, 1980, 1鸸 ָ 20 ־ ٰ ô ƼǾƿ ȸ ʷ ȣη° ڿ ½ϴ.
1990-2000뿡 , ϴ , ī , /ȫ ؿ ̶ũ/ø , ȸ ã ̵ ֹε ϴ.
2019 , 2õ ο 76 ȣ,340 Ƶ 1 ȸ ֹ 1,600 ҿܵ ̵ 鿡 ȸ ϰ ֽϴ.