def convert_str( str , time_now = ::DateTime.now , time_zone: "+09:00" )
      rational_for_time_zone = ::Kernel.Rational(9,24)
      time_now = time_now.new_offset( rational_for_time_zone )

      if str.string? and time_now.instance_of?( ::DateTime ) and ::PositiveStringSupport::RegexpLibrary.string_of_hour_and_min =~ str
        return ::DateTime.new( time_now.year , time_now.month , time_now.day , $1.to_i , $2.to_i , 0 , rational_for_time_zone )
      end

      raise "Error: The variable(s) are not valid. (\'str\'\: #{str} / Class: #{str.class.name})"
    end
def convert_str( str , time_now = ::DateTime.now , time_zone: "+09:00" )
      rational_for_time_zone = ::Kernel.Rational(9,24)
      time_now = time_now.new_offset( rational_for_time_zone )

      if str.string? and time_now.instance_of?( ::DateTime ) and ::PositiveStringSupport::RegexpLibrary.string_of_hour_and_min =~ str
        return ::DateTime.new( time_now.year , time_now.month , time_now.day , $1.to_i , $2.to_i , 0 , rational_for_time_zone )
      end

      raise "Error: The variable(s) are not valid. (\'str\'\: #{str} / Class: #{str.class.name})"
    end
hh:mm の形の文字列を、DateTime のインスタンスに変換するメソッド
 @param str [String] 変換する文字列
 @param time_now [DateTime] 生成されるインスタンスに年月日の情報を付加するためのインスタンス（デフォルトは現在時刻）
 @return [DateTime]