• Journal of Navigation and Port Research
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• v.40 no.3
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• pp.97-103
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• 2016

The precise prediction of ships propulsion performance is very important to find out the ships optimum route. This paper describes the development of computer program to generate the database of propulsion performance for the ships optimum routing system. The propulsion performance of ship in the sea is caused by not only ships conditions such as drift and hull roughness, but also various sea conditions such as wave and wind. These prediction methods of added resistance are based on the ships speed trial analysis methods of the ISO 15016:2002 standard, and a few prediction methods of the wind and hull roughness are supplemented. These prediction methods have been applied to the comprehensive computer program. And the database calculation for the research ice breaker the Araon has been carried out, which shall be used for the calculation of optimum route. Furthermore, this program shall be used for the route optimization in global shipping routes.

• Journal of the Society of Naval Architects of Korea
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• v.37 no.3
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• pp.1-10
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• 2000

It is very important to understand the flow characteristics for design of the hull forms with better resistance and propulsive performance. The experimental results explicating the local flow characteristics are also invaluable for validation of the CFD codes for both inviscid and viscous flow calculations. This paper describes the techniques and equipment developed for the measurement of wave pattern on the free surface and local mean velocity fields around the stern of the modern container ship with bow and stern bulbs in KRISO towing tank. The results contained in this paper can provide the valuable information on the flow characteristics of the modern commercial hull form of small block coefficient with high speed.

• Journal of the Society of Naval Architects of Korea
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• v.34 no.4
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• pp.21-30
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• 1997

This paper describes the experimental method of a pod-type waterjet propulsion system in a towing tank and shows the experimental analysis and test results of a designed waterjet propulsion system to be used for a hybrid high speed craft. The cruising performance of this craft is estimated from the results of the hull resistance test and waterjet test under the assumption that the interaction between the hull and the inlet pod is very small. A pod-type waterjet system with an axial pump was designed and a stand-alone waterjet experimental system was developed. Useful data such as the pump performance, the jet efficiency, the losses of inlet duct and nozzle were obtained. Test results show a good agreement with the design requirement.

• Journal of the Society of Naval Architects of Korea
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• v.58 no.3
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• pp.182-190
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• 2021

Computational simulations of turbulent flows around a model ship have been performed to investigate an influence of TVD schemes on the accuracy of advective terms associated with ship resistances. Several TVD schemes including upwind, second-order upwind, vanLeer, and QUICK as well as a nonTVD linear scheme were studied by examining temporal and spatial characteristics of accuracy transition in adjacent cells to the hull. Even though vanLeer scheme was the most accurate among TVD schemes in both structured and unstructured grid systems, the ratio of accuracy switch from 2^nd order to 1^st order in vanLeer scheme was considerable compared with the 2^nd order linear scheme. Also, the accuracy transition was observed to be overally scattered in the unstructured grid while the accuracy transition in the structured grid appeared relatively clustered. It concluded that TVD schemes had to be carefully used in computational simulations of turbulent flows around a model ship due to the loss of accuracy despite its attraction of numerical stability.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.35 no.6B
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• pp.859-866
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• 2010

Digital vessels can occur large a disaster at sea because vessels in fire and collision in case of certain unforeseen circumstances. In this paper, We propose digital vessel context monitoring system through risk analysis. We propose environment information analysis system using wireless sensor that have to acquire marine environment and context of marine digital vessel. For conducting simulation, we chose 300 data sets to train the neural network. As a result, we obtained about 96% accuracy for fire risk context and we obtained 88.7% accuracy for body of vessel risk context. To improve the accuracy of the system, we implement a FEC (Forward Error Correction) block. We implemented digital vessel context monitoring system that transmitted to diagnosis result in CDMA.

• Journal of Navigation and Port Research
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• v.34 no.6
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• pp.417-422
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• 2010

In this study, the resistance performances of barge are analyzed by model tests and computation using CFD to investigate the flow characteristics around a barge in still water. The model tests are carried out in infinite depth in Inha Technical College Circulation Tank to observe the resistance and the numerical simulations based on VOF(Volume of Fluid) method are performed to analyze the flow around the barge. We have selected two barge models to investigate the flow characteristics according to the different type of barges. The experiments are carried out with the models from 5kts to 10kts(designed speed 7kts) considering the effect of adverse and favorable current. The numerical simulations are performed to analyze the flow and resistance characteristics of barge in the full loaded condition with the target speed and compared with the experimental data to confirm the reliability of the numerical method. The result was that the difference of resistance with 25% occurred at low speed and EHP increased rapidly from 7kts.

• Journal of the Korean Society for Marine Environment & Energy
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• v.17 no.4
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• pp.318-323
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• 2014

When a disabled ship is being towed in a seaway, the speed and direction of the towed ship are estimated by using the towing force and direction of the selected tug boats at the predicted sea conditions including the wind and currents. In this paper, prediction method at the towing conditions of the various towing operations for a disabled ship are studied. The proposed calculation method suggests firstly the method to import the speed and resistance of the forward direction of the towed ship calculated by the existing computer program, second, the method to calculate the speed and resistance of the towed direction of the towed ship acquired from the selected tug boats at the initial towing conditions and lastly, the method to calculate the speed and resistance of the towed direction for the towed ship at the stable towing conditions. These calculation methods have been applied to the computer program and this program has been approved to be a useful program, capable of appropriately predicting the towed ship's conditions.

• Journal of the Korean Society of Marine Environment & Safety
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• v.22 no.2
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• pp.246-252
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• 2016

In this study, conceptual design of the fore-body hull form of catamaran type dredging vessel was performed that can effectively remove the contaminated sediments in coastal seabed. The hull form was simpled for the easy hull construction and the resistance performance was investigated to find out the effect of hull form parameters between variation of waterline and angle of entrance, etc. The relation between resistance performance and characteristics of free surface flows according to variation of bow forms was investigated by model testing in the circulating water channel and using Ansys CFX. The improvement of ship resistance performance to the wave resistance decrease due to improved wave pattern has been verified according to move the stem and the volume of the shoulder to the fore part of the vessel.

• Journal of the Korean Society for Marine Environment & Energy
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• v.9 no.2
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• pp.92-97
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• 2006

Hull forms of a high speed small boat have been developed through numerical studies. A round bilge type hull form has been drived form a using chine hull form with HCAD, a hull form variation software. Wave resistance and the flow fields around the ships have been computed using well-known software, WAVIS. This software employs Rankine source method with non-linear tree surface condition as well as dry transom boundary conditions. The round bilge hull form showed better resistance performance than to the chine hull form for the whole speed range. However, considering the building and labor costs of the small shipyard, the chine hull form has been selected and its wave resistance characteristics has been improved by modifying the bow regions and applying the stem wedge. It is found that the effect of stem wedge is quite satisfactory to improve the resistance characteristics of high speed chine hull form.

• Journal of the Korean Society of Marine Environment & Safety
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• v.25 no.7
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• pp.936-944
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• 2019

Submarines, which have been called an invisible force, are strategic underwater weapon systems that perform missions such as anti-surface warfare, anti-submarine warfare, and high payoff target strikes with the advantage of underwater covertness. A submarine should be able to withstand the hydrostatic pressure of the deep sea. In this respect, the submarine pressure hull, as the main structural system to resist the external pressure corresponding to the submerged depth, should ensure the survivability from hazards and threats such as leakage, fires, shock, explosion, etc. To do this, the initial scantling of the submarine pressure hull must be calculated appropriately in the concept design phase. The shape of the aft transition ring varies according to its connection with the submarine aft end conical structure, pressure hull cylindrical part, and non-pressure hull of the submarine; the design of the aft transition ring should not only take into account stress flow and connectivity but also the cost increase due to the increased man-hours of its complex geometry. Therefore, trade-off studies based on the four different shapes of the aft transition ring are carried out considering both the review of the structural strength through nonlinear finite element analysis (FEA) and economic feasibility by reviewing the estimations of the manufacturing working days and material costs. Finally, the most rational structural aft transition ring shape for a submarine amongst four reviewed types was proposed.