def get_dut1(utc)
      dut1 = 0
      target = utc.strftime("%Y%m%d")

      begin
        Const::DUT1S.reverse.each do |date, sec|
          if date <= target
            dut1 = sec
            break
          end
        end
        return dut1
      rescue => e
        raise
      end
    end
def get_dut1(utc)
      dut1 = 0
      target = utc.strftime("%Y%m%d")

      begin
        Const::DUT1S.reverse.each do |date, sec|
          if date <= target
            dut1 = sec
            break
          end
        end
        return dut1
      rescue => e
        raise
      end
    end
=========================================================================
 DUT1 (= UT1(世界時1) - UTC(協定世界時)) の取得

 * Ref: http://jjy.nict.go.jp/QandA/data/dut1.html

 @param:  utc   (Time Object)
 @return: dut1  (sec)
=========================================================================