# File lib_ctrl/rucy/jconv.rb, line 13
    def jtou8(data)
      return '' if data.empty?
      begin
        @Uconv.u8tou16(data)   # test UTF-8
        return data
      rescue
        # auto-conversion of Japanese encoding
        return @Uconv.euctou8(@NKF.nkf('-e', data))
      end
    end