var width, height;
if(size == 'L'){
	width = '700';
	height = '600';
}else{
	width = '500';
	height = '500';
}

var html = '<iframe src="http://chat-svr.jaga.jpn.org/chat.php?channel=' + channel + '&tag=' + tag + '&site_url=' + encodeURIComponent(site_url) + '&site_name=' + encodeURIComponent(site_name) + '&bgcolor=' + encodeURIComponent(bgcolor) + '&width=' + width + '&height=' + height + '" border="0" frameborder="0" width="' + width + '" height="' + height + '"></iframe>';
document.write(html);