php에서 '특정 문자열'만 인코딩 방식이 엉뚱하게 검사됩니다.

function detectEncoding($input) {
	$detected_encoding1 = mb_detect_encoding($input, ['EUC-KR', 'UTF-8']);
	$detected_encoding2 = mb_detect_encoding($input, ['UTF-8', 'EUC-KR']);
 
	if ($detected_encoding1 === $detected_encoding2) $detected_encoding = $detected_encoding1;
	else {
		$pattern = '/\A[\x{20}-\x{7E}\x{AC00}-\x{D7A3}]*\z/u'; // ascii characters and Hangul characters('가' to '힣')
		if (preg_match($pattern, iconv($detected_encoding1, 'UTF-8', $input))) $detected_encoding = $detected_encoding1;
		else $detected_encoding = 'UTF-8';
	}
 
	return $detected_encoding;
}
 
function detectEncodingAndPrint($input) {
	$detected_encoding = detectEncoding($input);
	echo $detected_encoding;
	if ($detected_encoding === 'UTF-8') echo $input;
	else echo iconv($detected_encoding, 'UTF-8', $input);
	echo "\n";
}
 
detectEncodingAndPrint('황치호');
detectEncodingAndPrint('Ȳġȣ');