const useScrollFadeIn = () => {
  const dom = useRef();
  
  const handleScroll = useCallback(([entry]) => {
      const { current } = dom;
    	
    	if(entry.isIntersecting) {
        // 원하는 이벤트를 추가 할 것
      }
    }, []);
  
  useEffect(() => {
    let observer;
    const { current } = dom;
    
    if (current) {
      observer = new IntersectionObserver(handleScroll, { threshold: 0.7 });
      observer.observe(current);
      
      return () => observer && observer.disconnect();
    };
  }, [handleScroll]);
  
    return {
    ref: dom,
  };
}