The Carbon Intensity Indicator (CII) regulation is a short-term measure of IMO for reducing GHG emissions from ships. In addition, the 2023 IMO GHG Strategy describes that the CII regulation is anticipated to create a potential synergy effect with other measures. Accordingly, the CII regulation, which took effect in 2023, is forecast to increasingly impact international shipping and the commercial vessel market. However, efforts to improve energy efficiency and implement slow steaming for ships are insufficient to meet the CII regulation that is increasingly stringent over time. Therefore, there is a growing need for fundamental improvements in future response strategies. In this study, major causes of low CII ratings for ships were investigated from a recent consulting project that was conducted to support shipping companies in satisfying the regulation from operational and technical perspectives. Lastly, proposals to implement the CII regulation effectively and to reduce GHG emissions from ships fundamentally were made, taking into account the major causes derived from the consulting.

On a global level, the pollution of the marine environment caused by marine plastic litter is becoming increasingly serious. Even if more than 80% of source of marine plastic litter comes from land-based activities, sea-based activities, such as losing fishing gear at sea, account for a significant amount of marine plastic litter. Accordingly, the discussion on the development of an action plan to address marine plastic litter from ships has begun since the IMO 73rd MEPC meeting. With regard to various measures to reduce marine plastic litter from ships at the international level, in this paper, the following issues will be introduced and discussed: (1) An accidental loss or discharge fishing gear (ALDFG) which has accounted for a significant portion of marine plastic litter from ships, (2) Encouragement for the ratification of the 2012 Cape Town Agreement (CTA) adopted by the International Maritime Organization (IMO), which outlines fishing vessel standards and includes other regulations designed to protect the safety of seafarers, (3) Development of a management system on containers lost at sea, which prevents a potential danger to maritime safety and a threat to the environment, particularly with regard to plastics, (4) Timeline of follow-up actions at the IMO level for the action plan to address marine plastic litter from ships. Finally, it emphasizes the fact that various and sensitive issues for solving marine plastic litter problems from ships still remain. Therefore, research in the aspect of related lpolicies and cooperation with related industries should be hightlighted based on the circumstances of each country.

As the improvement of ship energy efficiency is emphasized internationally, researches for this are being conducted in various ways. Accordingly, research is being conducted on the application of ORC power generation systems for ships using waste heat from the main engine exhaust gas generated during operation. The WHRU constituting the ORC system must be designed so that stable-phase change heat transfer occurs. In this study, a design study was conducted using the ANSYS CFX program for the production of a WHRU capable of generating ORC power generation output for a 30-kW ship using R134a refrigerant. A WHRU capable of achieving 30 kW generation output performance was designed while changing various design elements (shape, tube diameter, number of tubes, number of stages, etc.) of the WHRU. As a result, it was confirmed that the refrigerant (R134a) in a liquid state at a temperature of 14.8°C entered at a flow rate of 1.06 kg/s, evaporated by the exhaust gas, and was discharged from the outlet in a state of vapor fraction 1 at a temperature of 56.4°C. The heat transfer rate of the WHRU was 219.2 kW, the pressure during the evaporation process was constant at 13.9 bar in absolute pressure, and the enthalpy was 220 kJ/kg at the inlet and 426 kJ/kg at the outlet, respectively.

The rapid adoption of alternative marine fuels has introduced safety challenges not fully addressed by regulatory frameworks developed for conventional fuels. This study examines how International Maritime Organization (IMO) safety regulations respond to the dominant risk characteristics of alternative fuels, focusing on LNG, LPG, methanol, and ammonia. A comparative analysis is conducted based on physicochemical properties, hazard pathways, and corresponding provisions under the IGF Code and Interim Guidelines. The results show that while the IGF Code provides a goal-based, flammability-centered framework, its extension to fuels with different risk profiles—such as toxicity and liquid-phase hazards—creates structural mismatches between dominant hazards and regulatory trigger mechanisms. In particular, reliance on flammability-based indicators (e.g., LEL) for safety system activation in toxicity-dominant fuels reveals a misalignment between regulatory assumptions and actual risk pathways. In addition, intensified conservatism in ammonia regulations enhances safety but raises challenges related to operability and regulatory predictability. The study concludes that future regulatory development should adopt an integrated framework aligning hazard-specific indicators with regulatory mechanisms and incorporating empirical evidence through the Experience Building Phase (EBP).