Diagram illustrating the floor impact sound insulation performance measurement settings used in the Korean engineering method based on the KS and Korean building regulation. The impact (red arrows) and receiving points (blue dots) are indicated on the floor plan of a typical Korean apartment building unit (area: 84 m²). I2 and I3 (R2 and R3) are points in the perimeter area. I1 and I4 (R1 and R4) are points in the virtual perimeter area, which was inside the measurement area marked by the dashed line.