JSON encoding problem output from PHP

<?php
/**
* * meal_api.php
* * Created: Tuesday, Jan 30, 2018
* 
* * Juneyoung KANG <[email protected]>
* * Gyoha High School
*
* * Creates a today school meal JSON file from the NEIS webpage.
* * Github : https://github.com/Juneyoung-Kang/meal-api/
*
* * How to use?
* http://juneyoung.me/api/school-meal/meal_api.php?countryCode=stu.goe.go.kr&schulCode=J100004922&insttNm=School &schulCrseScCode=4&schMmealScCode=2/
* 
* * For more information, visit github and see README.md
*
* * Licensed under The MIT License
*/

header('Refresh: 60');                        // refresh every 60sec

error_reporting(0);                           // error reporting disable
header("Content-type: text/html; charset=UTF-8");        // // json type and UTF-8 encoding

require "simple_html_dom.php";                // use 'simple_html_dom.php'

$countryCode = $_GET['countryCode'];          // local office of education website
$schulCode =  $_GET['schulCode'];             // school code
$insttNm = $_GET['insttNm'];                  // school name
$schulCrseScCode = $_GET['schulCrseScCode'];  // school levels code
$schMmealScCode = $_GET['schMmealScCode'];    // meal kinds code

// // custom date
// // $schYmd = $_GET['schYmd'];

$MENU_URL = "sts_sci_md01_001.do";            // view weekly table

$today=date("Y.m.d");                         // get date using date() function. ex) 2018.01.01
$day=date("w");                               // get day using date() function. ex) 0==Sunday, 1==Monday, 6==Saturday

// // url for today
$URL="http://" . $countryCode . "/" . $MENU_URL . "?schulCode=" . $schulCode . "&insttNm=" . urlencode( $insttNm ) . "&schulCrseScCode=" . $schulCrseScCode . "&schMmealScCode=" . $schMmealScCode . "&schYmd=" . $today;

// // DOMDocument
$dom=new DOMDocument;

// // load HTML file 
$html=$dom->loadHTMLFile($URL);
$dom->preserveWhiteSpace=false;

// // get elements by tag name
$table=$dom->getElementsByTagName('table');
$tbody=$table->item(0)->getElementsByTagName('tbody');
$rows=$tbody->item(0)->getElementsByTagName('tr');
$cols=$rows->item(1)->getElementsByTagName('td');

// // check blank has values
if($cols->item($day)->nodeValue==null){
    echo '';
}else{
    $final=$cols->item($day)->nodeValue;
}

// // replace unnecessary characters
$final=preg_replace("/[0-9]/", "", $final);
$final=str_replace(".", "", $final);

// // change code number to text
if($schulCrseScCode==1){
    $schulCrseScCode="Kindergarten";
}
if($schulCrseScCode==2){
    $schulCrseScCode="Elementary School";
}
if($schulCrseScCode==3){
    $schulCrseScCode="Middle School";
}
if($schulCrseScCode==4){
    $schulCrseScCode="High School";
}
if($schMmealScCode==1){
    $schMmealScCode="Breakfast";
}
if($schMmealScCode==2){
    $schMmealScCode="Chinese";
}
if($schMmealScCode==3){
    $schMmealScCode="Dinner";
}

// // no meal
if($final==null){
    $final="No school meals today.";
}

// // array
$array[] = array(
    'Education Code' => $countryCode,
    'School Code' => $scholCode,
    'School name' => $instNm,
    'School Type' => $schulCrseScCode,
    'School Meal Type' => $schMmealScCode,
    'Date' => $today,
    'Menu' => $final
);

$fp = fopen('meal.json', 'w');
fwrite($fp, json_encode($array, JSON_UNESCAPED_UNICODE | JSON_PRETTY_PRINT));
fclose($fp);

?>

[
    {
        "교육청 코드": "stu.goe.go.kr",
        "학교 코드": "J100004922",
        "학교 명": ": "êµí•˜ê³ ë“±í•™êµ",
        "학교 종류": "ê³ ë“±í•™êµ",
        "급식 종류": "중식",
        "ë‚ ì§œ": "2018.02.09",
        "메뉴": "오늘은 급식이 없습니다."
    }
]