• Journal of Advanced Marine Engineering and Technology
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• v.32 no.2
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• pp.256-261
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• 2008

The purpose of this study is to propose practicable configurations against Rapid Load Down like propeller racing of ships which have been using SOFC/GT hybrid system on board. This paper suggests four kinds of countermeasures against propeller racing. The types A and B keep a fixed load of SOFC and save a surplus electric power to a storage system. In types of C and D, the load of SOFC is changed with the propeller racing. The best desirable countermeasure for Rapid Load Down depends upon the size of the ship, the propulsion power, and the characteristics of the engine system.

• Journal of Power System Engineering
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• v.11 no.1
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• pp.98-106
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• 2007

This paper presents a statistical prediction procedure for the propeller racing of ships with twin screw propellers sailing in ocean waves. The propeller racing is one of the most important factors of seakeeping qualities in relation to the safety of main engine and shafting system. It is especially significant key word for designing the twin-screw-propeller-type ship in view of allowable maximum propeller diameter etc.. In former studies, the propeller racing generally means the situation (propeller exposed) in which the relative motion amplitude between ship hull and wave surface would exceed a depth of point in rotary disk propeller. Therefore, it seems that the magnitude of the amplitude and its exceeding frequency have been examined as a principal subject of study as usual. However, the time during which the amplitude exceeds a depth of point must be also one of most important factor affecting the trend of propeller racing. This paper proposes a simply practical method for estimating the time lasting of exposed propeller related to twin screw propeller racing in rough confused seas on the basis of the statistics. Then, it is confirmed that the practical method is useful and convenience for considering the propeller racing in the stage of the basic design.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2020.11a
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• pp.72-74
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• 2020

일반적으로 선박조종에 필요한 중요한 성능으로 보침성능, 변침성능, 선회성능, 정지성능을 중요하게 여긴다. 이러한 조종성능은 선체의 선형과 함께 타와 엔진으로 표현될 수 있으며 특히 엔진의 성능은 선박의 안전운항과 직결되어 있다. 따라서 선박이 충분한 출력을 확보하지 못하면 항내조선시 선박의 안전을 담보하기 힘들며 또한 황천항해시 외력을 이기고 선박을 안전하게 조선하기 힘들다. 본 연구에서는 2020년 4월 6일 발생한 밀라노브릿지 사고를 통해 선박의 엔진출력을 저해하는 요소인 프로펠러 레이싱, 공전현상, 벤틸레이션 현상에 대하여 고찰하고자 하며 이를 통하여 선박의 조종성능에 미치는 출력을 중요성에 대하여 강조하고자 한다.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.43 no.3
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• pp.222-231
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• 2007

This paper represents a basic statistical examination on the navigability of ocean-going ship from the point of estimating the time lasting period when propeller racing occurred by using the basic probability theory and the statistics. The propeller racing is one of the most important seakeeping qualities in relation to the safety of the main engine and shafting system. The trend of the racing has been mainly investigated in order to estimate allowable maximum propeller diameter, operation of ocean-going ships, etc.. In those studies, the propeller racing generally and mainly means the situation (propeller exposed) in which the relative motion amplitude between ship hull and wave surface would exceed a depth of point in rotary disk propeller. Therefore, it seems that the magnitude of the amplitude and its exceeding frequency of propeller racing have been examined as a principal subject of study as usual. However, the time during which the amplitude exceeds the depth of point, that is, the propeller exposes in the air, must be also one of most important factor affecting the trend of propeller racing. Then, this paper proposes a new practical method for estimating the time lasting of exposed propeller related to propeller racing in rough-confused seas on the basis of the linear strip theory and the statistics. And, numerical examples of estimating the propeller racing probability are given for four wide ship forms. Finally the usefulness of the proposed method for predicting propeller racing based on the time lasting period is discussed.