External stores on low-speed rotorcraft are subjected to various external forces depending on the aircraft's operating conditions. While there are different types of external forces, this paper focuses on flight loads as defined by US defense specifications. Flight loads consist of static and dynamic loads. Static loads on aircraft external stores include inertial loads resulting from aircraft maneuvers and aerodynamic loads caused by the downward flow of the main wing. To define the inertial load, the inertial load factor on external stores was calculated, while the minimum analysis case for aerodynamic load was derived from trim analysis of rotorcraft blades. The critical design load diagram was developed by combining these factors, and ANSYS was utilized to analyze the structural robustness under static loads. Based on the characteristics of the main wing, a finite element analysis was conducted using a vibration profile tailored to the actual operating environment and an impact profile suitable for the impact conditions. Structural robustness was further assessed through actual tests. This analysis provides essential data for airworthiness certification, allowing for the safe installation of external stores on low-speed rotorcraft.

In this paper, we developed a virtual model predicting the tool deflection induced surface error and investigated the sensitivity and direction of the maximum surface error in various tool geometries and cutting conditions. The characteristics of the error were classified into the axial sensitive, radial sensitive, robust, overcut, and overlap zones according to the depth of cut. The maximum surface error was sensitive to the uncertainty of the radial depth of cut and robust to axial depth variation at the finishing process using a small radial depth of cut. The radial sensitivity was reduced by a large helix angle of tool. The sensitivity was decreased by increasing the depth of cut and it arrived at zero in the robust zone where the maximum surface error was not changed by both radial and axial depths of cut. An overcut occurred if axial and radial depths were deep and the overcut zone was enlarged by the helix angle and the number of teeth.

In this study, aluminum, used throughout the industry and actively studied for surface modification, is selected as the test subject. Micro-structured through acid etching, nano-structured through alkali treatment to maximize surface roughness, and the superhydrophilic surfaces were fabricated by forming the surface chemicals into aluminum hydroxide (Al(OH)₃). The superhydrophobic surfaces were fabricated through the self-assembled monolayer coating on the surface, and the surface structure and components were analyzed. The superhydrophilicity and superhydrophobicity were applied on the aluminum surface at the bottom of the low speed water vehicle. For the superhydrophilic and superhydrophobic surfaces, the reasons for the drag reduction performance on the bare surface and the difference in the amount of reduction were analyzed. A coating material that strong bonds with the surface are selected for anti-corrosive performance under NaCl solution. To verify that, the contact angle was measured by exposing each prepared aluminum surface to a 3.5% NaCl solution for 14 days. Additionally, we analyzed why the superhydrophobic surfaces were robust against the NaCl solution.

This paper presents a finite-time tracking control for a robot manipulator in the presence of a modeling uncertainty and an external disturbance. To solve the large chattering phenomenon that is caused by the high switching gain of the slidingmode control, a novel second-order sliding-mode controller that generates a continuous control input is designed with a robust differentiator. The finite-time stability of the closed-loop system is ensured using a constructive Lyapunov-stability analysis. Finally, a numerical simulation of the 2-Axis Pan-Tilt system is performed to verify the effectiveness of the proposed controller.