Thermal imaging plays a vital role in structural health monitoring of various materials and provides insight into the defect present due to aging, deterioration, and fault during construction. This study investigated the effectiveness of spatial filters during pre-processing of thermal images and a correlation technique in post-processing, as well as exploited its application in non-destructive testing and evaluation of defects in steel structures. Two linear filters (i.e., Gaussian and Window Averaging) and a non-linear filter (i.e., Median) were implemented during pre-processing of a pulsed thermography image sequence. The effectiveness of implemented filters was then assessed using signal to noise ratio as a quality metric. The result of pre-processing revealed that each implemented filter is capable of reducing impulse noise and producing high-quality images; additionally, when comparing the signal to noise ratio, the Gaussian filter dominated both Window Averaging and Median filters. Defect size was determined using a correlation technique on a sequence of pulsed thermography images that had been pre-processed with a Gaussian filter. Finally, it is concluded that the correlation technique could be applied to the fast measurement of defect size, even though the accuracy may depend on the detection limit of thermography and defect size to depth ratio.

The growing accessibility of small satellite technologies and international cooperation frameworks has enabled many emerging countries to initiate space development activities; however, the mechanisms through which they build and advance satellite development capabilities remain insufficiently theorized, as existing models such as the Space Technology Ladder capture only high-level milestones. To address this gap, this study proposes the Satellite Technology Ladder (SaTL), a structured 16-level framework integrating satellite development methods and satellite size as indicators of technological maturity. We conducted a comprehensive longitudinal analysis of all satellite projects initiated since 1990 across 16 emerging countries, coding each project according to the SaTL scheme and evaluating national trajectories over time. The analysis reveals four distinct developmental trajectories: (1) prolonged dependence on foreign procurement, (2) gradual capability enhancement through externally supported development, (3) expansion of domestic industrial ecosystems following initial collaboration, and (4) independent development from the outset based on pre-existing technological foundations. These findings demonstrate that technological advancement depends not only on technology introduction but also on absorptive capacity, institutional learning, and broader industrial structures. SaTL thus offers a theoretically grounded and empirically validated tool for assessing capability formation and informing policy strategies in emerging spacefaring nations.