## 1 Introduction
Thus, to prevent buildings from collapsing in case of a large-scale earthquake while minimizing resultant  
Figure 1: RC buildings damaged by shear failure after the 2017 Pohang Earthquake. human and property damage, it is necessary to develop an economical and effective seismic retrofitting method to improve the seismic performance of structures that are likely to be vulnerable to earthquakes, and especially RC buildings with non-seismic details, which are highly likely to undergo shear failure in their columns. Moreover, these seismic retrofitting measures must be conducted in an efficient and economical manner based on the expected earthquake magnitude and resultant damage. Conventional methods for retrofitting the seismic performance of existing RC buildings are mostly based on approaches using stiffening members, such as reinforcing bars, PC, structural steel, and steel plates, or extending cross-sections by placing additional concrete. Additional wall installation, cross-sectional extension, steel-plate reinforcement, steel-brace reinforcement methods are among the most widely used conventional seismic retrofitting methods [6; 7; 8; 9; 10; 11]. However, these conventional methods come with the following disadvantages [8]. * Add to the overall weight of buildings. Given the weak foundations of domestic RC buildings with non-seismic details, the application of such methods may require foundation reinforcement work to support the weight increase. * Difficult to secure enough workspace during the retrofitting process. * Among the most widely used retrofitting methods, steel-plate reinforcement involves difficulties in material transport and pressing work due to the weight of used steel plates. When steel plates are pressured against affected structures, in particular, it is difficult to determine if the substrate and steel plates have properly adhered to each other. In some cases, such a reinforcement rather negatively affects the building with the reinforced steel plates being suspended from the substrate, instead of supporting it. * Require construction precision. In attempts to addressing the disadvantages of conventional repair and retrofitting methods, as mentioned above, research has been actively carried out since the early 1990s on retrofitting methods using new composite materials, such as carbon fiber, Aramid fiber, and glass fiber [12; 13; 14; 15; 16]. These methods, however, also come with disadvantages as follows [16]:  
* Require pretreatment to treat rough surfaces. * Involve reinforcement anisotropy, where the degree of reinforcement varies depending on the directions in which fibers are aligned. * Allow limited workspace, especially for construction work in a narrow space. As described above, at a time when there is an urgent and increasing need for measures to address earthquake hazards (seismic retrofitting), conventional seismic retrofitting methods, such as additional wall installation, cross-sectional extension, steel-plate reinforcement, steel-brace reinforcement, and other methods using new composite materials, have some disadvantages to be actually applied to domestic buildings and structures, e.g., weight increase and cost-effectiveness. The recent demand from the public for more active measures to ensure the seismic stability of buildings against earthquakes has led to the development and implementation of various seismic structural control systems. The US's ASCE 7-10 [17] provides specific procedures to implement seismic control design, separately for both seismic control systems, including dampers and earthquake resistance systems. Korea's KDS 41 [5] also provides criteria for the design of seismic control systems, including seismic isolation and damping structures, to be applied in structural design. In general, however, these conventional seismic control systems [18; 19] are installed in the construction phase.