## 5 Discussion  
The new slot-type structural design concept was manufactured and verified with environmental tests to confirm its bottom-line requirement. Both the random and sine-burst vibration shows its compliance to the minimum mechanical strength and stiffness requirements. According to the JAXA accommodation handbook, the minimum natural frequency of satellites is defined as 60 Hz. The measured natural frequency of the STM design for 3U was around 310 Hz.  
The assessment results from the count and complexity analyses strongly suggest that the new slot-based structural design showed superior advantages by providing a more efficient integration process. It was possible to reduce the structural part count of the conventional design by 42% and 51% for the 3U and 1U satellites, respectively. The improvement in the part count provides three major benefits. First, the few required assembly steps to finish integrating the satellite led to an increase in the speed of the entire process of satellite development. On the other hand, having fewer structural parts also means a reduction in manufacturing costs. The cost is also directly related to the amount of tolerance required. A higher stack-up tolerance also leads to higher tolerance on individual parts level. As the number of parts increases, the stack-up tolerance increases to achieve the tolerance requirement defined by the CubeSat design specification, which causes a dramatic increase in production costs. The last advantage acquired with the minimum part count is its contribution to the reduction in complexity during integration.  
Complexity is a key factor that decides the level of simplification of the integration that impacts productivity. The complexity analysis shows a similar improvement as the part count analysis. The 3U slot design provides 40.43% reduction as compared to the conventional-type designs. On the other hand, a 68.02% change in the complexity for the case of the 1U slot design shows a significant change.  
As discussed before, the complexity of the assembly increases with the number of components and joints. An increase in complexity usually leads to workmanship errors due to difficulty grasping the assembly process. Despite the overall improvement achieved, the amount varies in terms of the level of sub-complexity variables. The minimum recorded improvement is in topological complexity, which indicates the need for further refinement in design. Based on the identified issues, further refinement in the design is being carried out for the current FM model. It is expected that upon the completion of the current FM model, the count and complexity values shall improve even further. In this design, the internal subsystems are standardized within the dimensions of 90 mm (about 3.54 in) by 86 mm (about 3.39 in); however, future work will consider enhancing the flexibility to accommodate components that are not standard enough to fit into the defined standard slot widths.  
Besides these major assessments, the implication of the reduction in part count and complexity, of the assembly step was evaluated. It takes 12 steps to complete the 3U slot structure assembly which is 58% reduction. The reduction in the number of assembly steps by more than half shows the method's suitability in terms of efficiency for fast integration missions. The scalability of the concept to lower the CubeSat factor demonstrates that this highly efficiency-demanding mission has potential feasibility on a 1U or higher form factor CubeSat platform.