In this study, based on the Building Register, status and existing structural criteria of small-scale steel-frame building is reviewed. As a result, the accumulated small-scale buildings account for about 85% of cumulative entire building. Furthermore, since 2000, the small-scale steel-frame buildings account for about 55% of the small-scale buildings. In other words, the proportion of small-scale steel-frame buildings has been increased. However, the structural criteria is not only insufficient but also structure for some small-scale steel-frame buildings does not have a reference.

An inter-layer noise problem in the apartment has been issued. An fundamental investigation has been carried in this study. An vibration-acoustic interactive analysis, has been selected to see the relationship between concrete slab thickness and its sound level in the apartment. Results showed that the sound pressure level had been decreased when the concrete slab thickness was increased. These results would be helpful to provide an useful information for developing of a high performance floor slab minimizing inter-layer noise.

Recently, a noise problem in the apartment has been broadly and socially issued. In this study, a numerical approach, i.e., vibration-acoustic interactive analysis, has been considered to investigate the relationship between damping ratio and the sound level in the apartment. From results, if the damping ratio has a range of 0 to 4 percentage, then the sound pressure level has been decreased. Finally, these results would be helpful to make a decision for developing of a high performance floor slab minimizing inter-layer noise.

Recently, a safety of the building has been issued. In this study, a statistical analysis of the licensing status of the building construction has been performed to check the trend of building construction. Finally, results of the statistical analysis would be helpful to improve of the building safety.

This study is to introduce a structural analysis method that can apply a unit modular system to a remodeling extension. The structural analysis process, which can reflect the behaviors between the existing building and the modular system, is performed in a five-staged structural analysis. Therefore, the example of structural analysis of an existing building is introduced.

This study is to establish a structural analysis method that can apply a unit modular system to a remodeling extension. Structural design has to be performed after considering the behaviors between the existing structures and the modular system because the modular system is added after the transformation of existing structures has been processed. The structural analysis process, which can reflect the behaviors between the existing building and the modular system, is introduced in a five-staged structural analysis.

This paper is the result of analysing the Building Register. It describes the ebb and flow about small-scale buildings for 5years. Major cities are rapidly decreasing small-scale buildings. On the other hands, Small and medium-sized cities are monotonic. Currently, All of the Korea buildings are occupied by small-scale buildings up to 82%. So, This researcher suggest that these buildings need to standardized design of structure for preparing earthquake and abnormal climate.

The purpose of this study is to develop structral technologies on the lightweight composite slab systems with sound reduction layers in the modular house. In this study, two kinds of slabs with minimum thickness was suggested reducing the floor impact sound. In order to evaluate the structural performance, the flexural strenth tests were carried out on the one-way full scale specimens. From the results of test, we know that the proposed slabs had ductile behavior and would be safe sufficiently.