function addbook_on(){
 var url = "https://www.ielts.co.kr/erpielts"; //url
 var title = "±¹³»1À§ ¾ÆÀÌ¿¤Ã÷ Àΰ­, À̾ËÇǾîÇпø"; //»çÀÌÆ®À̸§
 var browser = navigator.userAgent.toLowerCase();

 //Mozilla, FireFox, Netscape
 if(window.sidebar) {
  window.sidebar.addPanel(title, url,"");
     }else if(window.external){
   if(browser.indexOf('chrome') == -1){   //IE
    window.external.AddFavorite(url,title);
   }else{
   alert('ctrl + D ¶Ç´Â command + D¸¦ ´­·¯ Áñ°Üã±â Ãß°¡Çϼ¼¿ä ');  //chrome
   }
   }else if(window.opera && window.print){    //opera
  return true;
   }else  if(browser.indexOf('konqueror') != -1){  //konqueror
   alert('ctrl + B¸¦ ´­·¯ Áñ°Üã±â Ãß°¡Çϼ¼¿ä ');
   }else  if(browser.indexOf('webkit') != -1){  //safari
     alert('ctrl + B¸¦ ´­·¯ Áñ°Üã±â Ãß°¡Çϼ¼¿ä ');
   }else{
   alert('ÇöÀç ºê¶ó¿ìÁ® Áñ°Üã±â Áö¿ø¾ÈµÊ ');
   }
}

$(".hover").mouseleave(
  function () {
    $(this).removeClass("hover");
  }
);