By Miyoung Kim SUWON, South Korea (Reuters) - Samsung Electronics Co plans to sell a variation of its flagship Galaxy S4 smartphone that will transmit data at nearly twice the normal speed, the head of its mobile business said on Monday. J.K. Shin, also co-chief executive of the world's biggest technology firm by revenue, said the phone would be sold in South Korea as early as this month. Samsung was in talks with several overseas carriers to take the phone, Shin told Reuters in an interview at Samsung's headquarters in Suwon, just south of Seoul. He declined to name the carriers. ...