• Journal of Advanced Marine Engineering and Technology
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• v.35 no.4
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• pp.388-396
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• 2011

The strengthened regulations for atmospheric emissions from ships have caused a necessity of new, alternative power system in ships for the low pollutant emissions and the high energy efficiency. Recently, new kinds of propulsion power system such as fuel cell system, which use hydrogen as an energy source, have been sincerely considered. Fuel conversion system to hydrogen is an essential part for fuel cell ship. We have investigated thermodynamically the steam reforming characteristics of hydrocarbons and alcohols for the fuel conversion systems.

• Journal of Advanced Marine Engineering and Technology
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• v.37 no.5
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• pp.446-452
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• 2013

Interest in the energy efficiency and carbon reduction technology is increasing. Many studies have done on the technologies of heat recovery systems, because over 30% of the total energy is released into the atmosphere with the exhaust gas flow. In this study, the Rankine cycle is analyzed in the optimum conditions given through the previous work. The result shows that the exergy efficiency is 0.53 and the output is 1.43 kW at the condition of the pressure ratio of 0.6 and the mass flow rate of 0.7.

• Journal of the Korean Society of Industry Convergence
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• v.27 no.4_2
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• pp.981-989
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• 2024

In recent years, there has been a growing focus on preserving the global environment and utilizing resources efficiently. The significance of energy conservation has led to the development of systems that recycle waste heat from factories and use eco-friendly refrigerants. This study aims to enhance the performance of adsorption-desorption systems using thermoelectric devices, which are known for their ability to convert temperature differences into electrical energy. The research focuses on improving the efficiency of these systems by integrating thermoelectric modules to cool the adsorption side and heat the desorption side, thus enhancing overall system performance. The experiments utilized a typical thermoelectric device and silica gel as the adsorbent. Key experimental parameters included varying the inlet air temperature and relative humidity on the desorption side. The results indicated that increasing the relative humidity of the inlet air on the desorption side significantly enhanced the overall mass transfer coefficient while reducing the completion time of the process. Similarly, higher inlet air temperatures led to an increase in the mass transfer coefficient and a decrease in process completion time. These findings suggest that optimizing the operational conditions of thermoelectric devices can substantially improve the performance of adsorption-desorption systems, offering potential benefits for applications in ventilation systems and other related fields.

• Journal of Power Electronics
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• v.16 no.1
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• pp.259-267
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• 2016

This paper presents a stand-alone variable speed constant frequency (VSCF) ship shaft generator system based on a brushless doubly-fed machine (BDFM). In this system, the output voltage amplitude and frequency of the BDFM are kept constant under a variable rotor speed and load by utilizing a well-designed current vector controller to regulate the control winding (CW) current. The control scheme is proposed, and the hardware design for the control system is developed. The proposed generator system is tested on a 325 TEU container vessel, and the test results show the good dynamic performance of the CW current vector controller and the whole control system. A harmonic analysis of the output voltage and a fuel consumption analysis of the generator system are also implemented. Finally, the total efficiency of the generator system is presented under different rotor speeds and load conditions.

• Journal of the Society of Naval Architects of Korea
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• v.31 no.1
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• pp.133-141
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• 1994

In this paper, experiences obtained during the development of MASS(Noise Analysis of Ship-board using SEA) are described. The results are summarized as follows. (1) The modelling techniques for ship structure and cabins are suggested. (2) Structureborne and airborne noise for a real ship were measured at sea trial and predicted by NASS. The differences between the two values are acceptably small for the cabins located on higher decks, although problems related with modelling of lower decks and evaluation of radiation efficiency were found.

• International Journal of Naval Architecture and Ocean Engineering
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• v.6 no.1
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• pp.151-161
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• 2014

In this study, an experimental investigation has been made of the applicability of outer-layer vertical blades to real ship model. After first devised by Hutchins and Choi (2003), the outer-layer vertical blades demonstrated its effectiveness in reducing total drag of flat plate (Park et al., 2011) with maximum drag reduction of 9.6%. With a view to assessing the effect in the flow around a ship, the arrays of outer-layer vertical blades have been installed onto the side bottom and flat bottom of a 300k KVLCC model. A series of towing tank test has been carried out to investigate resistance (CTM) reduction efficiency and improvement of stern wake distribution with varying geometric parameters of the blades array. The installation of vertical blades led to the CTM reduction of 2.15~2.76% near the service speed. The nominal wake fraction was affected marginally by the blades array and the axial velocity distribution tended to be more uniform by the blades array.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2014.10a
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• pp.170-172
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• 2014

In this paper, one of reliable schemes of In-ship sensor networks using a Grid-based WPAN is proposed. The proposed scheme is based on a novel grid network which allows a multi-path communication, and is robust, energy efficient. The results demonstrate that the proposed Grid-based WPAN outperforms the IEEE 802.15.4 based network in terms of power efficiency.

• Journal of Advanced Marine Engineering and Technology
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• v.36 no.5
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• pp.586-594
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• 2012

A future type ship power system requires both economic and eco-friendliness. That is, this should be reduced the discharge quantity of air pollutants and green-house gases as well as have high energy efficiency. Recently, gas turbines have been realized a lot of technical development in terms of efficiency and safety, and are widening the example of their adoption to a GT/ST hybrid system in a power plant as well as an aviation use. This paper reviewed the performance characteristics of a GT/ST hybrid system of several ten MW class, not large capacity, with a simulation in order to evaluate the possibility of a GT/ST hybrid system for ships. The reviewed GT/ST hybrid system has maximum 49 % efficiency, has the highest efficiency point for TIT, and has a 70~75 % and 25~30 % load ratio for a gas turbine and a steam turbine respectively.

• Journal of Advanced Marine Engineering and Technology
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• v.39 no.10
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• pp.1054-1061
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• 2015

The International Maritime Organization (IMO) has been regulating emissions by making mandatory the compliance with institutions aimed at protecting air quality such as the Energy Efficiency Design Index (EEDI), Ship Energy Efficiency Management Plan (SEEMP) and Tier III. Under the circumstances, one of the response measures considered to be the most feasible is the replacement of existing marine fuel with Liquefied Natural Gas (LNG). The industry has been preemptively building infrastructure and developing and spreading engine technology to enable the use of LNG-fueled ships. The IMO, in turn, recently adopted the International Code of Safety for Ships Using Gases or Other Low-Flash-Point Fuels (IGF Code) as an institutional measure. Thus, it is required to comply with regulations on safety-related design and systems focused on response against potential risk for LNG-fueled ships, in which low-flash-point fuel is handled in the engine room. Especially, the Standards of Training, Certification and Watchkeeping (STCW) Convention was amended accordingly. It has adopted the qualification and training requirements for seafarers who are to provide service aboard ships subject to the IGF Code exemplified by LNG-fueled ships. The expansion in the use of LNG-fueled ships and relevant facilities in fact is expected to increase demand for talents. Thus, the time is ripe to develop methods to set up appropriate STCW training courses for seafarers who board ships subject to the IGF Code. In this study, the STCW Convention and existing STCW training courses applied to seafarers offering service aboard ships subject to the IGF Code are reviewed. The results were reflected to propose ways to design new STCW training courses needed for ships subject to the IGF Code and to identify and improve insufficiencies of the STCW Convention in relation to the IGF Code.

• Journal of Advanced Marine Engineering and Technology
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• v.41 no.1
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• pp.15-20
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• 2017

The International Maritime Organization(IMO) has adopted and implemented compulsory regulation for reducing greenhouse gas emission that cause global warming. However, with global warming underway, the IMO plans to enforce voluntary carbon dioxide emissions reduction based on the Ship Energy Efficient Management Plan and the Energy Efficiency Operational Indicator(EEOI) in the near future. Large container ships sail at low speeds in order to save fuel and reduce carbon dioxide emissions. However, bulbous bows designed for high-speed ships decrease fuel efficiency by acting as resistance when reduced speeds are adopted by large container ships. In order to adopt low-speed operations and increase fuel savings, the bulbous bow of a large container ship was modified into the proper shape and size. Fuel consumption was compared for checking the result of EEOI before and after modifying the bulbous bow adopted on low speed operation of large high-speed ships. The results confirmed much larger carbon dioxide emissions reduction than expected. If EEOI would be implemented as compulsory regulation for reducing carbon dioxide emissions, bulbous bow modification can be considered as one of the fuel saving methods for the high-speed ships.