Array
(
    [0] => Array
        (
            [user_email] => example@gmail.com
            [available_date] => 2018/06/30
            [available_time] => 06.00,06.30,07.00,07.30
        )

    [1] => Array
        (
            [user_email] => example@gmail.com
            [available_date] => 2018/06/31
            [available_time] => 06.30,07.00,07.30,08.00
        )

    [3] => Array
        (
            [user_email] => newuser@gmail.com
            [available_date] => 2018/06/31
            [available_time] => 08.00,08.30,09.00,09.30
        )

    [4] => Array
        (
            [user_email] => newuser@gmail.com
            [available_date] => 2018/06/30
            [available_time] => 08.30,09.00,09.30,10.00
        )

)
)

Array
(

    [0] => Array
        (
            [user_email] => example@gmail.com
            [date_time] => Array
            (
              [0]=>Array
                (
                  [date] => 2018/06/30
                  [time] => 06.00,06.30,07.00,07.30,
                )
              [1]=>Array
                (
                  [date] => 2018/06/31
                  [time] => 06.30,07.00,07.30,08.00,
                )
             )
        )

    [1] => Array
        (
            [user_email] => newuser@gmail.com
            [date_time] => Array
            (
              [0]=>Array
                (
                  [date] => 2018/06/31,
                  [time] => 08.00,08.30,09.00,09.30,
                )
              [1]=>Array
                (
                  [date] => 2018/06/30,
                  [time] => 08.30,09.00,09.30,10.00,
                )
             )
        )

)