• Journal of the Korean Society of Marine Environment & Safety
• /
• v.30 no.1
• /
• pp.135-145
• /
• 2024

At the 80th session of the MEPC, the IMO presented an enhanced GHG reduction strategy. The strategy is more specific and robust than the initial strategy presented at the 72nd session. The IMO aims to achieve 'Net Zero' GHG emissions from international shipping by 2050. In this study, a risk assessment was conducted for representative green fuels, namely. LNG, hydrogen, methanol, and ammonia. The fuzzy method was used to resolve the subjective ambiguity of results from the survey of the experts, and the positive and negative ef ects of the fuzziness were derived through the TOPSIS method. Finally, the closeness coefficients of the considered alternative fuels were determined using the Vertex method. As a result, methanol, LNG, hydrogen, and ammonia were preferred. This study suggests that the proposed approach can be used as a collective decision-making tool for selecting alternative fuels.

• Plant Journal
• /
• v.16 no.3
• /
• pp.37-41
• /
• 2020

Lately old LNG carriers increased and ship price is getting down. So Interest for reuse and modification of used LNG carriers is growing. Also the needs for replacement of old power plant is increasing. Additionally eco friendly fuel such as LNG become attractive. Consequently gas power plant is getting much more popular than before. So in this research planning, we consider the floating power plant by modifying LNG carriers. This plant has the various function including storage, power plant and bunkering fuction etc. Through this multifunctional plant, we are ready for the old power plant shutdown and energy crisis in the future when we can supply the urgent mobile floating power plant quickly in time.

• Journal of Sensor Science and Technology
• /
• v.17 no.4
• /
• pp.308-316
• /
• 2008

For the measurement of liquid level in ship's cargo tank, ballast tank, fuel oil tank and fresh water tank, several types of gauge meter are used such as tubular type, magnetic float type, reflex type transparent type and welding pad type. Among them, magnetic float type gauge meter is environmental friendly device because it is free of power source and maintenance. The main obstacle of the device is relatively large error bound. In this paper, finite element method is used to design and analysis of the magnetic float type gauge meter. The operation of reed switch according to the magnetic field has been successfully described and agreed well with experimental measurement. The optimum geometry with combination of permanent magnet and reed switches are designed to achieve 98 % accuracy of fluid level.

• Special Issue of the Society of Naval Architects of Korea
• /
• 2017.10a
• /
• pp.59-62
• /
• 2017

Recently oil price has got lower, but energy efficiency has been considered as an important factor to minimize ship operational costs and reduce greenhouse gas emissions. For the reason, it is necessary that energy efficiency improvement for hull form design and operational performance reflect an understanding of the vessel's operational profile. Throughout the life of the vessel, this can lead to important economies of fuel, even if, in some cases, a small penalty can be taken for design condition. In the present paper, hull form was developed for 5,000TEU class container carrier at given operation profile. As a CFD result at several design point, optimized hull form has improved resistance performance in comparison with the basis hull form. To reducing the viscosity and the wave resistance at multi draft and multi speed, the hull form was investigated for Cp-curve, frame and local shape. Numerical study has been performed using WAVIS & Star-CCM+ and verified by model test in the towing tank.

• Journal of Power System Engineering
• /
• v.9 no.4
• /
• pp.65-70
• /
• 2005

A liquid storage rectangular tank structures are used in many fields of civil, mechanical and marine engineering. Especially, Ship structures have many tanks in contact with inner or outer fluid, like ballast, fuel and cargo tanks. Fatigue damages are sometimes observed in these tanks which seem to be caused by resonance with exciting force of engine and propeller. Vibration characteristics of these thin walled tanks in contact with fluid near engine propeller are strongly affected by added mass of containing fluid. Therefore it is essentially important to estimate the added mass effect to predict vibration of the tank structures. Many authors have studied vibration of cylindrical and rectangular tanks structures containing fluid. Few research on dynamic interaction among tank walls through fluid are reported in the vibration of rectangular tanks recently. In case of rectangular tanks, structural coupling between adjacent panels and effect of vibration modes of multiple panels on added mass have to be considered. In the present paper, coupling effect between panels of tank structure on added mass of containing fluid, the effect of structural constraint between panels on each vibration mode for fluid region have investigated numerically and experimentally.

• Journal of Power System Engineering
• /
• v.14 no.6
• /
• pp.67-74
• /
• 2010

Many tanks are installed in ship and marine structures. They are often in contact with inner or outer fluid, like ballast, fuel and cargo tanks. Fatigue damages are sometimes observed in these tanks which seem to be caused by resonance with exciting force of engine and propeller. Vibration characteristics of these thin walled tanks in contact with fluid near engine and propeller are strongly affected by added mass of containing fluid. Therefore it is essentially important to estimate the added mass effect to predict vibration of the tanks. Many authors have studied vibration of cylindrical and rectangular tanks containing fluid. Few research on dynamic interaction among tank walls through fluid are reported in the vibration of rectangular tanks recently. In case of rectangular tanks, structural coupling between adjacent panels and effect of vibration modes of multiple panels on added mass have to be considered. In the previous report, A numerical tool of vibration analysis of a 3-dimensional tank is developed by using finite element method for plates and boundary element method for fluid region. In this paper, the coupling effect between panels of a tank on added mass of containing fluid, the effect of structural constraint between panels on each vibration mode for fluid region and mode characteristics in accordance with changing breadth of the plates are investigated numerically and discussed.

• Corrosion Science and Technology
• /
• v.10 no.4
• /
• pp.136-142
• /
• 2011

Al alloys have been used widely for commercial and military ships in most ocean countries since mid-1950s, and the value as light metal with high mechanical strength has been proven. As the safety and fuel efficiency of Al ships have improved, she can carry more freight, sail faster and travel longer distances. Furthermore, in the shipbuilding industry, Al alloys are applied as structural materials for ships to various areas including the deck of luxurious cruises, battleships and leisure ships. In addition, Al alloys are being spotlighted as environmental-friendly material as they can be recycled even after end of lifespan. However, Al alloys for ships must be carefully selected after considering corrosion resistance, endurance, strength, and weldability in sea water environment. Al alloys to satisfy these conditions are used widely include 5000 series Al-Mg alloy and 6000 series Al-Mg-Si alloy. Thus, this study selected and evaluated the cavitation characteristics of the 5000 series Al alloys that are used in hulls that directly contact seawater and the 6000 Al alloys that are used in the upper structures of ships. Results of cavitation test with time, weightloss and cavitation rate of 5456-H116 showed the smallest damage among 5052-O, 5456-H116 and 6061-T6.

• Journal of Advanced Marine Engineering and Technology
• /
• v.38 no.9
• /
• pp.1070-1074
• /
• 2014

According to IEEE 1662(2009), IPS is a power system where all prime movers produce electrical power that is shared among propulsion, mission, and ship service loads. Discriminating attributes of integrated power systems are flexibility of movers' arrangements, mechanical decoupling between prime movers and propulsors, an increased level of energy conversion and transmission redundancy, and flexibility of redistributing available electrical power for future electronic weapons. IPS could have various steps of power that can be produced at optimal load of movers. In this study, an evaluation method for optimal arrangement of movers was investigated when an IPS warship is projected. The two factors are utilized for the quantitative analysis which are the weight of system as the fighting power and the fuel consumption per year as the economic feasibility. And also the ways for arrangement of system were studied according to existence of small diesel generator. The evaluation method that decides the optimization level is based on the DEA(Data Envelopment Analysis)

• Journal of Navigation and Port Research
• /
• v.39 no.6
• /
• pp.439-450
• /
• 2015

This study objects to find characteristics in chemical tanker markets and to determine optimal chemical tanker size using a total shipping cost in main trading route of asia chemical tankers .Precedent studies of determination of the optimal ship size and case studies about chemical tankers was carried out and tried to introduce a cost model which is applicable to chemical tanker. This study is dependant on numerical analysis and involves scenario analysis to minimize sensitivity of results. This analysis shows as follows. First, 12,000DWT tanker is an optimal size on the 'Far East-Middle East' services, 9,000DWT tanker is a most competitive on the 'Far East-South East Asia' services and 3,000DWT tanker is a most economic size on the 'Inner Far East' services at average market situation. Second, the bigger size of chemical tanker, the more competitive advantage the tanker will obtain when bunker fuel prices rise. Small size ship gets more competitive during bunker prices down. Third, market fluctuation of time charter rate for chemical tanker is less than 20% against its average time charter hire which means less volatile. And tanker's competitiveness per each size is remained mostly same when time charterer rates rise at same proportion. Fourth, bigger size chemical tankers have cost advantages when tanker's quantity of each part cargo increase. And small-sized tanks are more competitive when part cargo scales decrease. For the last, ship's port stay strongly influences on the determination of the optical tanker size. When vessel has shorter port stay, bigger-sized tanker will be more competitive and even can be competitive if applies in short voyage as well.

• Journal of Advanced Marine Engineering and Technology
• /
• v.39 no.7
• /
• pp.722-728
• /
• 2015

The demand for shipboard energy management is expected to gradually increase based on ship energy efficiency management plans (SEEMPs), which have been in use since January 1, 2013. Therefore, the fuel consumption of the main engine, which occupies the greatest portion of the energy used, along with elements related to the engine power, should be strictly monitored. There are many different methods for indicating the engine power. However, this study performed an experiment to monitor the status of a ship's engine power in real time using an encoder and a proximate switch, which are economical to purchase and easy to install. In the experiment, the angular velocity during one cycle of a two-stroke low-speed engine was measured, and the measured data were converted to the torque fluctuation. The angular velocity during an abnormal firing condition in the cylinder was also measured, and the torque fluctuation as a result of a misfire was considered. The results were compared with sea trial data to determine the reliability. In this study, the status of the engine power was determined using the torque fluctuation of the main engine in an operating ship.