Steel bars are simple steel products with a strikingly long length compared to their cross-sectional size and are classified according to the shape of their cross-sections, such as round, angle, flat, hexagonal, octagonal, semi-circular, etc. A special shape called deformed bar (uneven bar) also exists. In addition, they are classified into three types based on their dimensions (diameter, diagonal distance, width), namely large, medium, and small. KS (Korean Industrial Standards) specifies various types of steel bars according to their steel grade and usage, such as general structural use, boiler use, rivet use, welded structural use, chain use, and so on. Those not conforming to these standards are called non-standard products. More than 90% of the demand for steel bars is for small ones, which are mainly used for construction purposes, followed by machinery and shipbuilding. (Refer to the illustration.) Steel bars come in various types, including angle steel, flat steel, hexagonal steel, octagonal steel, semi-circular steel, deformed bars, large steel bars, medium steel bars, small steel bars, merchant bars, and more.