• Journal of Advanced Marine Engineering and Technology
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• v.33 no.2
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• pp.282-287
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• 2009

As current international guideline and IMO regulation give severe restrictions for ships to manage ballast water to reduce unintentional organism transfers, several ballast water treatment systems recently have been being developed together with filtration. That is because discharging ballast water from ships causes many pollutions by foreign biological invasive species. The primary treatment system being considered in this study was based on fine screen filtration technology applied to ballast water filter in ballast tank in order to reduce the load of ballast water treatment system. New ballast water filtration system was invented and analysed. The structural stress and strain analysis for ballast filtration systems which are current and invented filters were carried out using UGS and Ansys. The results showed that the structure of current filtering module was not designed to meet the requirement of sea water filtration during ballasting operation. The studies also showed that the invented design of filtration system equipped with back washing and automatic scrapper for eliminating cake of bio-species might be a potentially effective technology for ballast water management of ship's ballast tank.

• Journal of Power System Engineering
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• v.17 no.2
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• pp.95-102
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• 2013

For vessels operating in the cold climate regions, the ballast water inside or hopper tanks above the waterline may be frozen, starting at the top of the tank and at the side walls. Therefore, countermeasures against freeze-up of the ballast tank such as air-bubbling system, hot steam injecting system, heating coil system and water circulating system are taken to prevent freeze-up phenomenon; however, there are no rigorous investigations of anti-freezing to examine the effectiveness and validity of systems against freeze-up of the ballast tank, in which the temperatures are about $-25^{\circ}C$ (ambient air temperature) and $0^{\circ}C$ (sea water), respectively. In this paper, to ensure reasonable specifications for cold regions if the measures from the above-mentioned systems against freeze-up are effective, the phenomenon of ballast tank freeze-up is simulated and discussed in low temperature conditions. With the results using the commercial CFD code, CFX 14, the most cost-effective solution is conducted to prevent being frozen along the outer surface.

• 한국기계연구소 소보
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• s.15
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• pp.117-125
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• 1985

It is usual practice to ballast a sip to maintain requires operational safety at sea. However, excessive ballasting may reduce the operational economy of a ship. Therefore, The determination of the optimal location and quantity of ballast water is one of the important works at the preliminary design stage. To provide a convenient tool to ship designers the program for the determination of the optimal location and program the effect of the change of ballast water quantity in each tank on some characteristics of a ship, such as trim, initial stability and heel, is investigated and the minimum quantity of ballast water for each tank which satisfies the operational safety requirements is calculated.

• Journal of the Society of Naval Architects of Korea
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• v.48 no.1
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• pp.93-97
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• 2011

When freezing is present on ballast water, it can impose additional loads on the hull and effect on stabilization of ship. The anti-icing techniques of ballast water, therefore, are key criteria for ship safety. The existing anti-icing techniques of ballast tank are hull heating, water circulation and air bubble system etc. In this research, anti-icing performance tests for the ballast water using micro-bubble system and sea water circulation system have been carried out at two temperature conditions($-10^{\circ}C$ and $-25^{\circ}C$). Ambient temperature, sea water temperature and temperature of the inner parts of the ballast tank are measured and also ballast water conditions are checked during the model test. The applied anti-icing techniques of ballast water, such as micro-bubble system and sea water circulation system show good performance in the low temperature conditions.

• Journal of Power System Engineering
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• v.17 no.5
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• pp.30-37
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• 2013

For vessels operating in the cold climate regions, the ballast water inside or hopper tanks above the waterline may be frozen, starting at the top of the tank and at the side walls. Therefore, countermeasures against freeze-up of the ballast tank such as air-bubbling system, hot steam injecting system, heating coil system and water circulating system are taken to prevent freeze-up phenomenon; however, there are no rigorous investigations of anti-freezing to examine the effectiveness and validity of systems against freeze-up of the ballast tank, in which the temperatures are about -$25^{\circ}C$ (ambient air temperature) and $0^{\circ}C$ (sea water), respectively. In this paper, to ensure reasonable specifications for cold regions if the measures from the above-mentioned systems against freeze-up are effective, the phenomenon of ballast tank freeze-up is simulated and discussed in low temperature conditions. With the results using the commercial CFD code, CFX 14, the most cost-effective solution is conducted to prevent being frozen along the outer surface.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2006.10a
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• pp.157-165
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• 2006

In February,2004, at International Maritime Organization (IMO), LONDON, a new international convention 'International Convention fur the Control and Management of Ship's Ballast Water and Sediment 2004' was adopted. It is called 'Ballast Water Management Convention (BWM)'. Ballast water means charged seawater or fresh water in ship's special tanks (ballast tank) to keep safety navigation and ship's maneuverability. However, from 1980, it was point out the serious problem for marine ecosystem and human life that ballast water includes harmful marine species (and small organisms) and these species are also discharged along with ballast water. These species were released with discharged ballast water in water areas, where species are different from discharged ballast water. The problem is that released species increase when released species are more powerful than native species and consequently, marine ecological system is destroyed in released water area. Authors have inspected the validity of the ballast water exchange using pumping-through method that is one of the methods of ballast water management. In this paper, the numerical simulation of the motion and density of the fluid at the time of exchange of the fluid in a 2-dimensional tank using the pumping-through method was carried out by using two different type numerical methods. One method is MPS method that is one of the particle methods. Other one is Finite Different Method (FDM). Authors were compared with result of two numerical method calculations and experiment result and reported some knowledge from these results.

• Transactions of the KSME C: Technology and Education
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• v.4 no.2
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• pp.85-92
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• 2016

During ballast of a LNG carrier, the mud at the sea floor can enter the tanks together with the ballast water if the LNG terminal is located at shallow water region. In order to remove the mud deposited on the tank floor during deballasting, the mud flushing system in the ballast tanks is applied. In this study, various analyses to conform the efficiency in the mud removal are performed. In order to design the mud flushing system, the particle size of the mud is measured by particle size analyzer. Flushing performance is evaluated by numerical analysis. From the results of numerical analysis including flow field and piping system network, the optimized flushing system is determined.

• Journal of the Society of Naval Architects of Korea
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• v.59 no.6
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• pp.400-412
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• 2022

This paper provides the results of numerical and theoretical predictions of oil outflows from damaged single-hull and double-hull ships.Theoretical equations derived from the unsteady Bernoulli equation and a CFD method for multi-phase flow analysis were used to estimate the oil outflow rate from cargo tank. The predicted oil outflow rate from a single-hull cargo tank damaged due to grounding and collision accidents showed a good agreement with the available experimental results in both numerical and theoretical analyses. However, in the case of the double-hull conditions, the time variation of the amount of water and oil mixture inside the ballast tank predicted by the theoretical equation showed some different behavior from the numerical results. The reason was that the interaction of the oil flow with the water inflow in the ballast tank was not reflected in the theoretical equations. In the problems of the initial pressure condition in the cargo and ballast tanks, the oil outflow and water inflow were delayed at the pressure condition that the tanks were sealed. When the flow interaction between the oil and water in the ballast tank was less complicated, the theoretical and the numerical results showed a good agreement with each other.

• Journal of the Society of Naval Architects of Korea
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• v.40 no.4
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• pp.46-52
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• 2003

In ship structures, many parts are in contact with inner or outer fluid as stern, ballast and oil tanks. Fatigue damages can be sometimes observed in these tanks which seem to be caused by resonance. Tank structures in ships are in contact with water and the vibration characteristics are strongly affected by the added mass of containing water. Therefore it is important to predict vibration characteristics of tank structures. In order to estimate the vibration characteristics, the fluid-structure interaction problem has to be solved precisely. In the present paper, we have developed a numerical tool of vibration analysis of 3-dimensional tank structures using finite elements for plates and boundary elements for water region. To verify the present analysis, we have made an experiment for vibration characteristics of a tank with elastic opposite panels. And the added mass effect of containing water and the effect of structural constraint between panels are investigated numerically and discussed.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.13 no.10
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• pp.791-797
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• 2003

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 or 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. In the previous report, we have developed numerical tool of vibration analysis of 3-dimensional tank structure using finite elements for plates and boundary elements for fluid region. In the present report, using the numerical analysis, vibrations characteristics In deep water tank are investigated and discussed.