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In response to the escalating climate change crisis, the International Maritime Organization has implemented stringent regulations to significantly improve the energy efficiency of ships. Consequently, the global shipbuilding and maritime industries are actively developing and deploying advanced technologies to comply with these rigorous regulations and further enhance the energy efficiency of maritime vessels. This study proposes a method for developing an optimal load-sharing control system that minimizes fuel consumption in vessels with varying shaft generator capacities and output characteristics. The system receives real-time data on the main engine, diesel generator, and electric power grid status to optimize load sharing and minimize total fuel consumption. Load sharing is achieved using the Lagrange interpolation formula to optimize the fuel oil consumption objective function for shaft generators and diesel generators operating in parallel. A specialized real-time controller, simulated using MATLAB/Simulink with real navigation data, demonstrated fuel savings of ~1.89% compared with conventional methods.

As advanced sensors and weapons require high power, naval vessels have increasingly adopted electric propulsion systems. This study aims to enhance the efficiency and operability of electric propulsion systems over traditional mechanical propulsion systems by analyzing the operational profiles of modern naval vessels. Consequently, a battery-integrated generator-based electric propulsion system was selected. Considering the purpose of the vessel, a specification selection procedure was developed, leading to the design of a hybrid electric propulsion system (comprising one battery and four generators). The power management control technique of the proposed propulsion system sets the operating modes (depending on the specific fuel oil consumption of the generators) to minimize fuel consumption based on the operating load. Additionally, load distribution control rules for the generators were designed to reduce energy consumption based on the load and battery state of charge. MATLAB/Simulink was used to evaluate the proposed system, with simulation results demonstrating that it maintained the same propulsion performance as existing systems while achieving a 12-ton (22%) reduction in fuel consumption. This improvement results in cost savings and reduced carbon dioxide emissions. These findings suggest that an efficient load-sharing controller can be implemented for various vessels equipped with electric propulsion systems, tailored to their operational profiles.

Advancements in the reduction of carbon dioxide emissions from ships are driving the development of more efficient onboard power systems. The proposed non-equivalent parallel running operation system is explored in this study, which improves the efficiency of the main power generation source compared with traditional equal load-sharing methods used in power management systems. However, the asymmetric method reduces the efficiency of the auxiliary power sources. To address this issue, we propose a control method that integrates a battery system with an efficiency-based algorithm to optimize the overall system performance. The proposed approach involves establishing operation command values based on the characteristics of the power generation source and adjusting these commands according to the battery’s state of charge (SOC). MATLAB/Simulink simulations confirmed the effectiveness of this method across various operating modes and revealed no operational issues. When applied to a ship’s operating profile over 222 h, the method reduced fuel consumption by approximately 2.98 tons (5.57%) compared with conventional systems. Over 38 annual voyages, this reduction equates to savings of 115.96 tons of fuel or approximately 96.47 million Korean won. This study demonstrates that integrating an optimal efficiency algorithm into the energy management system significantly enhances both the propulsion and overall energy efficiency of ships.

In this study, a method is proposed to minimize electrical load fluctuations and improve the efficiency of engine generator operation by managing refrigerated ship containers through an integrated control system. The proposed system actively controls the electrical load by assigning operational priorities based on cargo temperature deviations to existing independently operated refrigerated containers, ensuring that they operate only within the available power of the engine generator. As a result, the average specific fuel oil consumption can be reduced. A 70 h simulation of the refrigerated containers, a power system, and an integrated control system demonstrated in MATLAB/Simulink 2021b that the magnitude of electrical load fluctuations decreases from 37.6% to 9.6% of the engine generator’s rated power compared with the conventional operation of refrigerated containers. In addition, a 1.88% fuel saving is realized.

Regulations on emissions from ships are being strengthened, and emission reduction systems and alternative technologies are being developed. In addition, the amount of emissions is closely related to the performance of the propulsion systems of the ship; however, performance measurement systems have mainly been developed for large commercial ships. For small and medium-sized ships, although the output of the propulsion system is rather low, the number of vessels sailing in the coast is very high. Therefore, a performance-monitoring system is required for small and medium-sized ships. However, for small and medium-sized ships, there are no suitable performance and emissions calculation systems. Conventional performance-measuring and analysis systems for large ships have difficulties in terms of their cost and installation when applied to small and medium-sized ships. In this study, a new system was developed that is able to calculate the speed, power, fuel consumption, carbon dioxide emission assumptions, and efficiency of a ship by receiving simple key data such as GPS, fuel flow, and rpm data rather than checking the ship’s condition using massive forms of data. The system transmits data to the shore’s remote-monitoring center in real-time through a communication network. Using these data, it is possible to estimate a ship’s aging factor, engine performance, amount of exhaust gas, etc., and the accumulated data of all coastal ships in a country can be used as basic data for governments to use to support eco-friendly ship policies.

The irradiation performance of U3Si dispersion fuel in an Al matrix, U3Si-Al, under the Hi-Flux Advanced Neutron Application Reactor (HANARO) design full-power condition of 30 MW was tested for full-power qualification of the fuel. A test assembly was fabricated containing 18 fuel rods made with atomized U3Si powder manufactured at the Korea Atomic Energy Research Institute. The test assembly was irradiated for 188 full-power operation days in the HANARO subject to the normal fuel-loading scheme and achieved about 60 at% U-235 average burnup and 75 at% U-235 peak burnup. The maximum linear power of the test assembly was 98 kW/m. Nondestructive and destructive postirradiation examinations were conducted. The measured postirradiation examination data were compared with data from previous irradiations and the design criteria required for HANARO fuel. Consequently, it was concluded that in-pile performance was acceptable and fuel integrity was maintained, and the behavior satisfied the fuel design requirements. Keywords: Fuel Qualification, HANARO, Postirradiation Examination Data, U3Si-Al Dispersion Fuel, U3Si Fuel

The construction project of the Kijang research reactor (KJRR), which is the second research reactor in Korea, has been launched. The KJRR was designed to use, for the first time, U–Mo fuel. Plate-type U–7 wt.% Mo/Al–5 wt.% Si, referred to as U–7Mo/Al–5Si, dispersion fuel with a uranium loading of 8.0 gU/cm3, was selected to achieve higher fuel efficiency and performance than are possible when using U3Si2/Al dispersion fuel. To qualify the U–Mo fuel in terms of plate geometry, the first miniplates [HANARO Miniplate (HAMP-1)], containing U–7Mo/Al–5Si dispersion fuel (8 gU/cm3), were fabricated at the Korea Atomic Energy Research Institute and recently irradiated at HANARO. The PIE (Post-irradiation Examination) results of the HAMP-1 irradiation test were analyzed in depth in order to verify the safe in-pile performance of the U–7Mo/Al–5Si dispersion fuel under the KJRR irradiation conditions. Nondestructive analyses included visual inspection, gamma spectrometric mapping, and two-dimensional measurements of the plate thickness and oxide thickness. Destructive PIE work was also carried out, focusing on characterization of the microstructural behavior using optical microscopy and scanning electron microscopy. Electron probe microanalysis was also used to measure the elemental concentrations in the interaction layer formed between the U–Mo kernels and the matrix. A blistering threshold test and a bending test were performed on the irradiated HAMP-1 miniplates that were saved from the destructive tests. Swelling evaluation of the U–Mo fuel was also conducted using two methods: plate thickness measurement and meat thickness measurement.

This article describes the preparation and pH-sensing characteristics of a sol-gel-based optical sensor. A fluorescent dye possessing a triethoxysilane pendant group (2) was synthesized and covalently immobilized onto a sol-gel matrix to afford an optically pH-sensitive membrane that operates in acidic solutions. The sensor membrane displays two distinctive absorption bands around 374 and 439 nm, and two emission bands around 520 with excitation at 340 and 460 nm. The fluorescence intensity and absorbance ratio of the sensor membrane increases as the pH increases from -1.0 to 2.0. The sensor membrane was reproducible, reversible, and stable for repeated measurements in acidic buffer solutions and has a long lifetime of at least a month without dye leaching. [ABSTRACT FROM AUTHOR]

Postirradiation annealing tests were performed to obtain the 133Xe diffusion coefficients in uranium dioxide (UO2) and mixed thorium-uranium dioxide [(Th-U)O2] fuels. Specimens were a single-grained UO2, a polycrystalline UO2, and a polycrystalline (Th-U)O2. The (Th-U)O2 specimen was a mixture of 35% ThO2 and 65% UO2. Each 300-mg specimen was irradiated to a burnup of 0.1 MWd/t U. Postirradiation annealing tests were performed at 1400, 1500, and 1600°C, continuously. The xenon diffusion coefficients for the nearly stoichiometric single-grained UO2 agree well with the dam of others. The xenon diffusion coefficients in the polycrystalline (Th-U)O2 am approximately one order lower than those in the polycrystalline UO2. The xenon diffusion coefficient in the (Th-U)O2 increases with the increasing oxygen potential of the ambient gas. [ABSTRACT FROM AUTHOR]