php 오류 질문드려요

https://sir.kr/g5_tip/17696

해당팁을 사용하고 있는데요. 이게 오류가 나더라구요.

오류내용은 

Warning: Cannot modify header information - headers already sent by (output started at /homepages/24/d908461896/htdocs/bbs/db_table.optimize.php:95) in /homepages/24/d908461896/htdocs/common.php on line 799

Warning: Cannot modify header information - headers already sent by (output started at /homepages/24/d908461896/htdocs/bbs/db_table.optimize.php:95) in /homepages/24/d908461896/htdocs/common.php on line 801

Warning: Cannot modify header information - headers already sent by (output started at /homepages/24/d908461896/htdocs/bbs/db_table.optimize.php:95) in /homepages/24/d908461896/htdocs/common.php on line 802

Warning: Cannot modify header information - headers already sent by (output started at /homepages/24/d908461896/htdocs/bbs/db_table.optimize.php:95) in /homepages/24/d908461896/htdocs/common.php on line 803

Warning: Cannot modify header information - headers already sent by (output started at /homepages/24/d908461896/htdocs/bbs/db_table.optimize.php:95) in /homepages/24/d908461896/htdocs/common.php on line 804

Warning: Cannot modify header information - headers already sent by (output started at /homepages/24/d908461896/htdocs/bbs/db_table.optimize.php:95) in /homepages/24/d908461896/htdocs/common.php on line 805

다음과 같구요.

일단 오류라인 내용은

db_table.optimize.php:95 오류라인

echo "<script>document.getElementById('ct').innerHTML += '$str';</script>\n";

common.php on line 799 ~ 805 오류라인

header('Content-Type: text/html; charset=utf-8');
$gmnow = gmdate('D, d M Y H:i:s') . ' GMT';
header('Expires: 0'); // rfc2616 - Section 14.21
header('Last-Modified: ' . $gmnow);
header('Cache-Control: no-store, no-cache, must-revalidate'); // HTTP/1.1
header('Cache-Control: pre-check=0, post-check=0, max-age=0'); // HTTP/1.1
header('Pragma: no-cache'); // HTTP/1.0

입니다.

이거 해결하려면 어떻게 하면 될까요?