Some idle spaces in the TV band, the so-called Digital Dividend have emerged through the TV channel rearrangement process as the one of the activities for DTV transition. Various wideband services including spectrum sensing application are currently being reviewed as DTV White Space application in order to cope with the wireless internet environment. However, it is hard to expect lots of DTV White Space due to geographical conditions and interference issues with broadcasters as incumbent users in the DTV band. In this paper, the authors are suggesting measures for DTV White Space usability by reviewing the availability of White Space from diverse aspects in order to improve the usage environment of DTV White Space. As a part of this study, narrowband applications have been considered for practical use of White Space from the aspect of efficient use of the DTV spectrum. Related to this, the TETRA system has been applied to this study as a narrowband application for DTV White Space. In addition, this study has suggested a direction for a DTV White Space management scheme that will be able to enhance spectrum efficiency by considering unoccupied channel conditions according to the density of DTV transmitters and relays at three DTV pilot regions in Korea, i.e. Uljin, Gangjin and Danyang. Especially, there has been a consideration of the regulatory criteria compatibility between the US and Korea in order to review the possibility of the physical expansion of DTV White Space, this study has been based on two kinds of minimum field strengths at part 73 of 47 CFR. Through computed calculations, the interoperable range of the TETRA system was reviewed according to the operating modes and power classes.