I will talk on the Mahler measure of some temper polynomials, construct the nontrivial integral element of the second K-group for certain tempered elliptic curves. I will also give a proof of Deninger's conjecture on the Mahler measure of x+1/x+y+1/y+1 by Beilinson's regulator map. (This conjecture is proved by M. Rogers and W. Zudilin in 2011).