철골 구조물 H빔 허용오차 3mm이내
<iframe width="1100" height="619" src="https://www.youtube.com/embed/zru8dwFQB2M" title="H빔&45평 조립식 철골구조물 제작 설치하는 방법!" frameborder="0" allow="accelerometer; autoplay; clipboard-write; encrypted-media; gyroscope; picture-in-picture; web-share" referrerpolicy="strict-origin-when-cross-origin" allowfullscreen></iframe>