• Journal of the Society of Naval Architects of Korea
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• v.49 no.6
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• pp.491-497
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• 2012

A hull-form for a 32,000G/T class Ro-Pax ferry has developed in accordance with a need of ferry operators to reduce fuel oil consumption(FOC) due to the drastic increase in oil prices recently and strengthening of environmental rules and regulations such as CO2 emission. A twin-skeg type is applied as the hull-form in lieu of an open-shaft type in order to improve propulsion performance. In order to achieve this object, flow control devices are installed to reduce a propeller induced vibration which is a main reason to obstruct the application of twin-skeg type passenger vessels owing to an uncomfortable vibration level. Numerical simulation by using an in-house code and a commercial code (Fluent) has performed to find out an optimum design of the flow control devices and to check an improvement in cavity volume. Model tests in Samsung Ship Model Basin are carried out to evaluate propulsion performance with the developed twin-skeg type hull and a reference hull of open-shaft type. In conclusion, it is shown that the twin-skeg type hull is better than the open-shaft in FOC by around 7% and in cavity volume by 20% as well.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.38C no.3
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• pp.288-295
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• 2013

In this paper, we compare the existing channel estimation technique for 4S (Ship to Ship, Ship to Shore) maritime communications under AWGN channel model, Rician fading channel model, and Rayleigh fading channel model respectively. In general, the received signal is corrupted by multipath and ISI (Inter Symbol Interference). The estimation of a time-varying multipath fading channel is a difficult task for the receiver. Its performance can be improved if an appropriate channel estimation filter is used. The simulation is performed in MATLAB. In this simulation, we use the popular estimation algorithms, LMS (Least Mean Square) and RLS (Recursive Least-Squares) are compared with respect to AWGN, Rician and Rayleigh channels.

• Proceedings of the KSR Conference
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• 2003.10b
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• pp.305-310
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• 2003

This study is intended to outline the lessons that can be learned from European experience of the opportunities and challenges involved in operating train ferries to carry freight. The study considers the various train ferry routes that have operated over recent years in Europe, examines their characteristics, and then proceeds to evaluate the economic viability of train ferries in general. On the basis of this analysis, we have attempted to outline the conditions that appear to be required under which Train Ferries may be competitive. This study shows that long crossing train ferries in Europe have survived where the adjacent railway systems handle a significant volume of domestic traffic and do themselves playa serious role in the transport industry. There is no reason to suppose railway wagons cannot be carried economically over long distances. Experience in Western Europe is that they are best operated as mixed road trailer and rail wagon services. Only the lower deck need carry railway wagons, which greatly simplifies loading and the physical construction of the ship. Existing road based ro-ro ferries can be adapted to become rail ferries. It is, however, essential that there is commercial clarity as to the responsibility for ensuring the overall service is viable. To that end, the ferry company is responsible for marketing the service and managing relationships between the two railway authorities.

• Journal of Ship and Ocean Technology
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• v.10 no.3
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• pp.36-48
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• 2006

The train ferry, accommodating trains roll on and off, is often called as 'Railway on the Sea' or 'Blue High-way' since she can connect the railways or roads segregated by the sea and improve the accessibility and continuity of land transport systems. The ferry is especially appropriate to the intermodal transport routes mostly passing through the land but have relatively short sea segment. As the train ferry can considerably reduce the cost and time for cargo handling and modal shift and unnecessitates excessive initial investment on infrastructures such as large harbor cranes or vast container yards, introduction of train Ro-Ro ferries lessen the total transport cost for door-to-door transportation with full exploitation of the existing railway system. All the ports placed in Shandong, Liaoning and Jiangsu provinces of China are connected to the hinterlands via well developed railway and road systems. Therefore, realization of the Incheon-Yantai train ferry system will link Korea railways to TCR and the 4,131-kilometer-long Longhai-Lanxin Railway, along the famous Eurasian Continental Bridge. In the present paper, the Incheon-Yantai train ferry will be introduced as a good example of an efficient multimodal short sea shipping system for Northeast Asia.

• Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
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• 2004.05a
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• pp.290-297
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• 2004

In this paper, one of the harbour maneuvering tests is described. Its goal is to investigate the so-called crabbing performance of ships. By crabbing is meant the ability of the vessel to move sideways with the use of her own maneuvering devices like propellers, rudders, transverse thruster, etc. the 3m ferry model is made by ocean engineering wide tank in the university of ulsan. when the model ship is leaving and going to the quay, Transverse forces and Yawing moments are measured, in the condition of zero longitudinal force and the design draught, by load cell attached to the longitudinal center of gravity on the ship. the purpose of the experiment is to verify the reliability of ocean wide tank in university of ulsan about crabbing test compared with results of foreign research institute.

• Journal of Advanced Marine Engineering and Technology
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• v.33 no.1
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• pp.52-61
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• 2009

This experiment was conducted in attempt of improving hydrodynamic efficiency of the propulsion mechanism by installing a spring to the wing so that the opening angle of the wing in one stroke can be changed automatically, compared to the existing method of fixed maximum opening angle in Weis-Fogh type ship propulsion mechanism. Average thrust coefficient was almost fixed with all velocity ratio with the prototype, but with the spring type, thrust coefficient increased sharply as velocity ratio increased. Average propulsive efficiency was larger with bigger opening angle in the prototype, but in the spring type, the one with smaller spring coefficient had larger value. In the range over 1.0 in velocity ratio where big thrust can be generated, spring type had more than twice of propulsive efficiency increase compared to the prototype.

• Journal of Advanced Marine Engineering and Technology
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• v.29 no.7
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• pp.769-778
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• 2005

The velocity and pressure fields of a ship's Weis-Fogh type propulsion mechanism are studied in this paper using an advanced vortex method. The wing (NACA0010 airfoil) and channel are approximated by source and vortex panels. and free vortices are introduced away from the body surfaces. The viscous diffusion of fluid is represented using the core-spreading model to the discrete vortices. The velocity is calculated on the basis of the generalized Biot-Savart law and the pressure field is calculated from an integral, based on the instantaneous velocity and vorticity distributions in the flow field. Two-dimensional unsteady viscous flow calculations of this propulsion mechanism are shown. and the calculated results agree qualitatively with the measured thrust and drag due to un-modeled large fluctuations in the measured data.

• Proceedings of the KSME Conference
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• 2004.11a
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• pp.1407-1412
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• 2004

The velocity and pressure fields of a ship's propulsion mechanism of Weis-Fogh type are studied by advanced vortex method. The wing of NACA0010 type and the channel are approximated by a finite of source and vortex panels, and the free vortices are introduced from the surface of their bodies. The viscous diffusion of fluid is represented by the core-spreading method. The velocity field is calculated on the basis of Biot-Savart law and the pressure field is calculated from the integration equation formulated by Uhlman. The flow fields of this propulsion mechanism are unsteady and complex, but the flow fields are clarified by numerical simulation.

• 한국전산유체공학회:학술대회논문집
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• 2005.10a
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• pp.305-310
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• 2005

The velocity and pressure fields of a ship's propulsion mechanism of the Weis-Fogh type, in which a airfoil moves reciprocally in a channel, are studied in this paper using the advanced vortex method. The airfoil and the channel are approximated by a finite number of source and vortex panels, and the free vortices are introduced from the body surfaces. The viscous diffusion of fluid is represented using the core-spreading model to the discrete vortices. The velocity is calculated on the basis of the generalized Biot-Savart low and the pressure field is calculated from integrating the equation given by the instantaneous velocity and vorticity fields. Two-dimensional unsteady viscose flows of this propulsion mechanism are numerically clarified, and the calculated results agree well with the experimental ones.

• Journal of Advanced Marine Engineering and Technology
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• v.32 no.7
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• pp.1036-1043
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• 2008

The Flow fields of a ship's propulsion mechanism of Weis-Fogh type were investigated by the PIV. Velocity vectors and velocity profiles around the operating and stationary wings were observed at opening angles of ${\alpha}=15^{\circ} and $30^{\circ}$, velocity ratios of V/U=$0.5{\sim}1.5$ and Reynolds number of Re=$0.52{\times}10^4{\sim}1.0{\times}10^4$. As the results the fluid between wing and wall was inhaled in the opening stage and was jet in the closing stage. The wing in the translating stage accelerated the fluid in the channel. And the flow fields of this propulsion mechanism were unsteady and complex, but those were clarified by flow visualization using the PIV.