Investigation of subsurface structure using seismic velocity Acquisition of Seismic Velocity section of subsurface layer         Investigation of Ground Structure, Stratum situation and Extraordinary zone Acquisition of Seismic Velocity imaging section of Ground Material         Investigation of Ground Structure Properties and Dynamic modulus(borehole to borehole) Acquisition of Seismic Velocity by Stratum         Investigation of Ground Structure Properties and Dynamic modulus(borehole to borehole) Acquisition of Seismic Velocity by Stratum