ajax 한글 깨짐 현상.. 도움부탁드려요.

$.ajax({
                    url:'insert.php',
                    dataType:'json',
                    type:'POST',
                    data:{'teset1':$('#test1').val(),
                        'test2':$('#test2').val()},
                    success:alert("성공")
                });

<?
    $data = "'{$_POST['test1']}','{$_POST['test2']}'";
    $sql = "insert into g5(
                                        test1,
                                        test2
                                    )";
    $sql .= "values(";
    $sql .= $data;
    $sql .= ")";
    sql_query($sql);
?>