function _logon()
{
 if(document.logon.user_id.value =="")
 {
  	alert("Member ID is reqired！");
	document.logon.user_id.focus();
	event.returnValue=false;
 }
 else if(document.logon.pass_word.value =="")
 {
   	alert("Password is reqired！");
	document.logon.pass_word.focus();
	event.returnValue=false;
 }
 else
 {
    document.logon.action="login.php";
    document.logon.submit();
 }
}