def get_utc_tai(utc)
      utc_tai = 0
      target = utc.strftime("%Y%m%d")

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

      begin
        Const::LEAP_SECS.reverse.each do |date, sec|
          if date <= target
            utc_tai = sec
            break
          end
        end
        return utc_tai
      rescue => e
        raise
      end
    end
=========================================================================
 UTC(協定世界時) - TAI(国際原子時) (= うるう秒総和) の取得

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

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