function initMoving(target, position, topLimit, btmLimit) {
 if (!target)
  return false;

 var obj = target;
 obj.initTop = position;
 obj.topLimit = topLimit;
 obj.bottomLimit = document.documentElement.scrollHeight - btmLimit;
 obj.style.position = "absolute";             // relative로 absolute로  이부분은 레이아웃에 따라 정의
 obj.top = obj.initTop;
 obj.left = obj.initLeft;
 if (typeof(window.pageYOffset) == "number") {
  obj.getTop = function() {
   return window.pageYOffset;
  }
 } else if (typeof(document.documentElement.scrollTop) == "number") {
  obj.getTop = function() {
   return document.documentElement.scrollTop;
  }
 } else {
  obj.getTop = function() {
   return 0;
  }
 }

 if (self.innerHeight) {
  obj.getHeight = function() {
   return self.innerHeight;
  }
 } else if(document.documentElement.clientHeight) {
  obj.getHeight = function() {
   return document.documentElement.clientHeight;
  }
 } else {
  obj.getHeight = function() {
   return 500;
  }
 }

 obj.move = setInterval(function() {
  if (obj.initTop > 0) {
   pos = obj.getTop() + obj.initTop;
  } else {
   pos = obj.getTop() + obj.getHeight() + obj.initTop;
   //pos = obj.getTop() + obj.getHeight() / 2 - 15;
  }

  if (pos > obj.bottomLimit)
   pos = obj.bottomLimit;
  if (pos < obj.topLimit)
   pos = obj.topLimit;

  interval = obj.top - pos;
  obj.top = obj.top - interval / 3;
  obj.style.top = obj.top + "px";
 }, 20)                        // 30은 속도를 의미
}