• 대한조선학회논문집
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• 제41권5호
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• pp.28-33
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• 2004

Generally Horn-type rudders have been used for single propeller and single rudder system. The reason is that the rudder torques of Horn-type rudder are smaller than those of Spade rudder with same lift force. But it is found that the rudder cavitation occurs on a Horn-type rudder of fast container ship. In this paper the comparison results of Horn-type and Spade rudders are described. HPMM tests are carried out to compare the effects of two rudder types on the maneuverability of a ship. It is shown that the maneuvering performance of a ship equipped with Horn-type rudder is better than that equipped with Spade rudder by comparing the test results and maneuvering coefficients at scantling condition. The reason is that the movable part area of Horn-type rudder is about 14％ larger than that of Spade rudder with same total area. And the rudder torque of Spade rudder is greater than that of Horn rudder. At ballast condition, however, the effect of rudder type is negligible.

• International Journal of Naval Architecture and Ocean Engineering
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• 제13권1호
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• pp.352-366
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• 2021

To decrease Europe's harmful emissions, the European Union aims to substantially increase its offshore wind energy capacity. To further develop offshore wind energy, investment in ever-larger construction vessels is necessary. However, this market is characterised by seemingly unpredictable growth of market demand, turbine capacity and distance from shore. Currently it is difficult to deal with such market uncertainty within the ship design process. This research aims to develop a method that is able to deal with market uncertainty in early ship design by increasing knowledge when design freedom is still high. The method uses uncertainty modelling prior to the requirement definition stage by performing global research into the market, and during the concept design stage by iteratively co-evolving the vessel design and business case in parallel. The method consists of three parts; simulating an expected market from data, modelling multiple vessel designs, and an uncertainty model that evaluates the performance of the vessels in the market. The case study into offshore wind foundation installation vessels showed that the method can provide valuable insight into the effect of ship parameters like main dimensions, crane size and ship speed on the performance in an uncertain market. These results were used to create a value robust design, which is capable of handling uncertainty without changes to the vessel. The developed method thus provides a way to deal with market uncertainty in the early ship design process.

• 한국항해항만학회지
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• 제46권2호
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• pp.73-81
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• 2022

Currently, shipping by sea is becoming common because of the low price and the safety of goods. The ship is designed as a larger vessel to meet the need of this development. In the design stage, the investigation of hydrodynamic forces acting on the ship hull is very important in predicting the ship's maneuverability. Given that the ship docks at various ports for loading or discharging goods, the ship usually operates in various loading conditions, depending on the site condition and other various factors. Hence, it is necessary to investigate the effect of the loading condition on the hydrodynamic forces acting on the ship, to most accurately determine the maneuverability of the ship. In this study, an experiment of Korea Autonomous Surface Ship (KASS) was conducted at the towing tank of Changwon National University to measure the hydrodynamic forces acting on the KASS. The loading condition considered in this experiment is determined based on the draft, which was decreased by 5% for each loading condition. The smallest draft is 85% of the design draft. The static test as Oblique Towing Test (OTT), Circular Motion Test (CMT), Circular Motion Test with Drift (CMTD) is performed in the various loading conditions. First, the hydrodynamic forces in the Oblique Towing test (OTT) are compared with the result of other institutes. Second, the hydrodynamic forces in various drift angle, yaw rate and loading conditions are measured. Finally, the influence of the loading conditions on the hydrodynamic coefficient is discussed.

• 한국군사과학기술학회지
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• 제19권4호
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• pp.526-535
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• 2016

In this study, the estimating weight data of eight leading ships of Korea navy were processed by comparing with the final weight data of their incline test results statistically, and are analyzed as follows; The maximum criteria of the weight margins of Korea naval ship in the preliminary and detailed design phases seem to be appropriate values, but the minimum criteria would be advisable to update more reasonable values. And, the limitation that the acceptable deviation of lightship weight should be 10 % of the lightship weight on a naval ship's ROC(Required Operational Capabilities) is recommended to be prohibited, because it comes from the weight estimation which has considerable uncertainty and it may also drop off design flexibility. Finally, the SWBS(Ship Work Breakdown System) groups which have larger deviation values in the estimating weight of naval ships are necessary to improve their accuracies, and to upgrade their weight database continuously.

• 수산해양기술연구
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• 제22권1호
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• pp.29-33
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• 1986

This paper aims at finding out the optimum operating condition to reduce fuel consumption for the training ship Pusan 402 with controllable pitch propeller. For this purpose, this paper examints the variation of ship speed and fuel consumption in accordance with the change of engine revolution and propeller pitch. The results obtained are as follows: 1. When engine revolution is constant, the ship speed sluggishly increases according to the increase of propeller pitch but fuel consumption extremely increases. The higher revolution the engine is, the more remarkable this tendency is. 2. As the engine revolution becomes lower, the fuel consumption per mile decreases. Howt.er = the fuel consumption under the same engine revolution differs according to the propeller pitch. 3. Specific fuel consumption is uniformed about 180g/ps.h at any case of load. 4. Among the various operating conditions which yield the same ship speed, fuel consumption lowers in the case of lower engine revolution and larger propeller pitch.

• 대한조선학회논문집
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• 제42권6호
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• pp.679-685
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• 2005

Until now, the stealth design to reduce the infrared signature of ship haven't been carried out using the proper design criteria. The study on the maritime meteorological environment in the Korean seas hasn't been accomplished yet, so the design criteria of the maritime meteorological environment was just given by the engineering sense without experience of the Navy and/or of the shipyard. Even in rather good conditions(summer condition), the estimated IR signature of a ship showed larger values and couldn't predict the worst condition during the operation of a ship at sea. In this study, domestic maritime meteorological data were collected and variables affecting the IR signature of a ship had been derived through the sensitivity study of IR signature according to the maritime meteorological environment in Korean seas. The basic study on the criteria of the stealth design of IR signature has been carried out.

• 대한조선학회논문집
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• 제54권2호
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• pp.83-89
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• 2017

Numerical simulations of ship resistance have been performed to compare spatial characteristics of Courant number when using structured and unstructured meshes. When Euler scheme was used for time integration, the structured mesh provided a more efficient calculation because the calculation time interval was larger than that of unstructured mesh. The automatic generation of very small meshes in the unstructured mesh was mainly responsible for the limitation of calculation time interval. When local time stepping Euler scheme was applied, however, the ship resistance of unstructured mesh showed a rapid convergence while a slow convergence of ship resistance in structured mesh was caused by the small time interval in bulbous bow.

• 스마트미디어저널
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• 제5권3호
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• pp.81-87
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• 2016

세계의 글로벌화에 따라 움직이는 물동량이 크게 증가하면서 선박의 해상 운송 능력 향상을 위해 선박의 대형화가 지속적으로 이루어지고 있으며 선박의 수도 크게 증가하고 있는 추세에 따라 선박에서의 위험지역 모니터링에 대한 관심 이 증대되고 있고 국제해사기구(IMO)를 중심으로 선박안전관련 국제협약의 기준이 강화되고 있는 실정이다. 국내는 2012년 해양경찰청에 의해 선박 위치정보 기반의 선박 사고예측 및 예방 시스템이 구축되었으나, 최근 세월호 사건 등 선박 사고에 대한 대응의 문제점이 지적되고 있는 실정으로 위의 문제점을 해결하고자 본 논문을 통해 위험 구역 경보 및 위급상황 시 선박 운항 위치정보를 자동으로 전달해주는 DGPS를 탑재한 웨어러블 타입의 즉각 응급대응 시스템을 설계를 하고자 한다.

• 대한조선학회지
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• 제21권1호
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• pp.3-12
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• 1984

Up to now, it has been common to treat the maneuvering motion of a ship as a 3-degree-freedom motion i.e. surge, sway and yaw on the sea surface, for the simplicity and mathematical calculation, and it is quite acceptable in the practical point of view. Meanwhile, considering the maneuverability of a ship under the special conditions such as in irregular waves, in wind or at high speed with small GM value, it is required that roll effect must be considered in the equation of ship motion. In this paper the author tried to build up the 4-degree-freedom motion equation by adding roll. And then, applying the M.M.G.'s mathematical model and with captive model test results the roll-coupled hydrodynamic derivatives were found. With these the author could make some simulating program for turning and zig-zag steering. Through the computer simulations, the effect of roll to the ship maneuver became clear. The effect of the wind force to the maneuverability was also found. Followings are such items that was found. 1) When roll is coupled in the maneuvering motion, the directional stability becomes worse and the turning diameter becomes smaller as roll becomes smaller as roll becomes larger. 2) When maneuver a ship in the wind, the roll becomes severe and the directional stability becomes worse. 3) When a ship turns to the starboard side, the wind blowing from 90 degree direction to starboard causes the largest roll and the largest turning diameter, and the wind from other direction doesn't change the turning diameter. 4) When a ship is travelling with a constant speed with rudder amidship, if steady wind blows from one direction, the ship turns toward that wind. This phenomenon is observed in the actual seaways.

• 한국군사과학기술학회지
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• 제16권4호
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• pp.545-552
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• 2013

This paper is a part of developing a computer code that can be used to generate IR images of a naval ship by considering the emitted and reflected infrared signals. The spectral radiance received by an IR sensor is consisted of the self-emitted component from the ship surface, the reflected component of the solar/sky irradiance at the ship surface, the emitted radiance from the ship surface and the exhaust plume gas, and the scattered radiance by the atmosphere. The plume gas radiance occupies a large part of the emitted radiance from a naval ship in operation. Therefore plume gas radiance must be taken into account when calculating the radiance from a naval ship for reliable IR images. In this paper, IR images of a naval ship with the exhaust gas effect in various environmental conditions are generated by using an exhaust gas prediction model called the JPL model. The contrast radiance (CR) values of the IR images are calculated to analyze the effect of the exhaust gas radiance quantitatively. The results obtained by quantitative analysis show that the IR signatures with the exhaust plume gas are 2.26 times larger than those neglecting the plume gas effect. The effect of the exhaust plume gas is shown to be more eminent in winter than in summer in the daytime.