[1] With the outbreak of World War II, he studied Japanese at the US Navy Japanese/Oriental Language School at the University of Colorado at Boulder.
According to William C. Sherman, in 1949 Miller was his deputy at the Performance Review Section of the Economic Cooperation Administration in Seoul.
He gave time and money to a number of worthwhile causes and extended personal assistance to many Koreans, including the continuing support of over 50 children.
In addition, the arboretum grounds are home to traditional tile-roofed wooden houses called hanok that he moved there and renovated.
[1] Miller and his arboretum have received many awards including recognition by the United Kingdom's Royal Horticultural Society, the U.S. Freedom Foundation and the South Korean government.