B<span>ecause oceans account for 70.8% of the Earth's surface, various Internet-of-Things (IoT) applications for the marine industry are being researched and developed. The success of an IoT technology in the maritime industry depends on the location tracking technology used and how far it can communicate. In this study, we implemented a marine observation system using low power wide area (LPWA) communication technology to provide maritime IoT services. The proposed marine observation system consists of a marine IoT module and an ocean observation monitoring system. The information collected is GPS information and communication signal reception strength. As a result of an actual field test, we were able to obtain the distance to the gateway by measuring the position through the marine IoT module, and we found that the intensity of communication was proportional to the change in sea level.</span>
Purpose: The gear strength of a new mechanical transmission designed to increase the loading weight of small 4.8 kW tracked agricultural transporters was analyzed. Design improvements to increase the gear strength and reduce the gear weight were proposed after examining the parameters. Methods: Sixteen operators from three regions were surveyed to obtain the usage profile of small 4.8 kW transporters. Gear strength was evaluated by calculating contact stress and tooth root stress using commercial software following ISO 6336. Results: From the strength calculation for each gear pair, contact stress smaller than tooth root stresses were produced in all gear pairs. The safety factors in most cases exceeded 1.0, except in the case of gear pair II in group II. The design life of the transporter using gear pair II in group II was 42% under harsh conditions-thus, this design life needs improvement. A robust design was proposed by examining the relevant parameters (face width and profile shift coefficient) to increase the design life of the transporter. In addition, a lightweight design for gear pair I in group II that was considered overdesigned was proposed by examining the face width to reduce the weight of the drive gear by 42% and that of the driven gear by 30%. Conclusions: The Safety factor for the design life was examined through a gear strength analysis. After examining the relevant parameters, conditions for strength improvement were proposed to increase design life or adjust overdesigned gear. However, load conditions differ depending on the working conditions or user's preferences; therefore, it is necessary to conduct further studies in various regions.
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