video Olaf Hochherz(electronics with book), Ryu Hankil (analog clockworks, piezo)   Olaf Hochherz(electronics with book), Jin Sangtae(HDD, PDA)   picture       올라프 호르허르츠 Olaf Hochherz : electronics (book with piezo) 류한길 Ryu Hankil : alalog clockwork with speaker feedback 진상태 Jin Sangtae : Hard disk drives with PDA