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Item Design and Simulation of a Regenerative Braking System for Small Electric Vehicles(GMIT, 2025) Sumiyadorj Rentsennorov; 1 st Supervisor: Prof. Ph.D. Sungchil Lee; 2 nd Supervisor: Ph.D. Kim Young SukSmall electric vehicles (SEVs), such as e-scooters and e-bikes, are becoming increasingly important for sustainable urban transport. However, their limited battery capacity significantly constrains range and usability, particularly in cities like Ulaanbaatar, where cold weather and limited charging infrastructure further exacerbate these issues. This thesis investigates the design, simulation, and prototype testing of a regenerative braking system (RBS) specifically tailored for lightweight SEVs, to improve energy efficiency through kinetic energy recovery during deceleration. The research begins with an exploration of the historical development and theoretical principles behind regenerative braking, including electromagnetic induction, Lenz’s Law, and energy conservation. A simulation model was developed in MATLAB/Simulink to replicate a realistic SEV drivetrain using a 12V brushed DC motor, an H-bridge inverter, a lithium-ion battery, and a control logic system for modulating torque. Simulations were performed under both regenerative and non-regenerative scenarios. The results showed that when braking was applied, the system recovered approximately 4.48 joules of energy from 38.87 joules consumed, achieving an energy recovery efficiency of 11.52%. In contrast, the coasting scenario confirmed zero energy recovery, highlighting the effectiveness of controlled regenerative braking. To validate the simulation, a hardware prototype was built using an Arduino Uno, L298N motor driver, ACS712 (1) current sensor, and a 14.8V 2800mAh battery pack. The prototype ran a similar 10-second drive-brake cycle, with real-time current and power readings collected to calculate energy use and recovery. While the simulation demonstrated ideal regenerative behavior, the physical system was limited by the L298N’s unidirectional current flow, allowing only dynamic braking but not true regeneration. Nevertheless, the prototype showed measurable reverse current during braking and achieved a recovery efficiency of 8.76%, confirming the system’s potential with improved hardware. This work concludes that regenerative braking can offer tangible energy savings in SEVs and provides a foundational model for implementing RBS in low-cost, micro-mobility systems. Future improvements, such as upgrading the motor driver to a bidirectional regenerative controller and integrating supercapacitor storage, are recommended to maximize energy recovery and system performance.Item FRAMEWORK FOR IMPLEMENTING UNMANNED HAULAGE TRUCK IN OPEN PIT MINE(GMIT, 2025) DULGUUN Battulga; 1 st Supervisor: Prof. Ph.D. Sungchil Lee; 2 nd Supervisor: Prof. Ph.D. Young Suk KimThe use of autonomous trucks can significantly enhance the operational efficiency, sustainability, and safety of both small and large open-pit mines. Automation protects workers from accidents and unhealthy environments while also improving their efficiency and productivity. Autonomous trucks offer many advantages over manually operated trucks, providing a more comfortable and safer working environment for workers and creating greater economic efficiency for companies in the long term. Although autonomous trucks travel at slightly slower speeds than Manual trucks, they are more productive because they eliminate the need for shift changes and lunch breaks. They also increase fuel efficiency by reducing idle time, saving approximately 0.06 liters of fuel per tonne hauled, and improving utilization rates by 10–13%. While these figures may not seem significant at first glance, they result in substantial savings over the long term. However, implementing an automated system requires time, a large amount of capital cost, and potential challenges, such as worker concerns about job security, which must be carefully managed. For the successful deployment of autonomous dump trucks, several factors must be considered, with infrastructure and safety being the most critical. For example, mine roads should be designed without sharp turns or steep slopes, as the vehicle's sensor system may misinterpret sharp changes and cause accidents. Additionally, if a person or vehicle without a radio frequency identification RFID) tag enters the automated zone, there is a heightened risk of collision and serious accidents. Therefore, autonomous vehicle zones must strictly adhere to ISO road standards, and unauthorized persons and vehicles must be strictly prohibited from entering the automated sections of the mine. It also includes information on factors influencing fuel consumption in automotive performance, such as road gradient, adhesion and friction coefficients, wind resistance, and methods for calculating appropriate gear selection on slopes. Additionally, identifying the most relevant data for this type of research proved to be a significant challenge.