• Journal of Korea Ship Safrty Technology Authority
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• v.16
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• pp.26-37
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• 2004

선박 추진축계의 진동은 크랭크축, 추력축 등의 이상마멸을 초래할 뿐 아니라 과도하면 선체진동을 유발시키기도 한다. 이러한 추진축계의 진동중에서 가장 빈번히 문제가 되는 것이 비틀림 진동이므로 축계의 초기설계 단계부터 이에 대한 신중한 검토가 필요하다 .

• Bulletin of the Society of Naval Architects of Korea
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• v.31 no.3
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• pp.16-20
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• 1994

본 고에서는 진동관점에서 특히 문제시되고 있는 장행정.소수실린더.저속 2행정 디젤주기관의 기진력 발생기구와 기관본체진동에 대하여 살펴보고, 박용디젤 추진축계의 진동문제와 관련해 서는 1980년 이후부터 본격적으로 시작된 국내의 연구사례들을 중심으로 이 분야에 대한 연구 현황을 소개하고 향후 중심적으로 연구해야 할 문제점들을 검토하고자 한다.

• Proceedings of the Korean Society of Marine Engineers Conference
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• 2006.06a
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• pp.5-6
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• 2006

대형 저속 2행정기관을 탑재한 선박에서 축계배치와 관련된 선미측 후부 메인엔진 베어링의 손상이 증가하는 경향이 있다. 메인엔진을 포함한 선체는 최적화로 인하여 변형하기 쉬운 경향에 있고, 고출력을 요구하는 추진 축계는 이것과 반대의 경향을 가지므로 축계 배치 변화에 대한 감도가 높아져서 메인엔진 베어링의 손상이 발생하게 된다. 이러한 문제에 대한 대책으로 메인엔진 베어링을 포함한 보다 정확한 배치계산을 할 필요가 있다. 이 논문에서는 축계배치계산 고정도화의 일환으로 메인엔진 베어링 수가 베어링 반력에 미치는 영향에 대하여 검토한다.

• Journal of Advanced Marine Engineering and Technology
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• v.40 no.9
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• pp.743-748
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• 2016

Ship's diesel engines have intrinsic problem to make vibrations caused by cylinder explosion and unbalanced rotating mass. These vibrations might induce noises, are transferred to hull and neighboring structures and cause secondary vibrations. This paper suggests the use of an additional dynamic absorber with a sub-vibration system to reduce the aforementioned vibrations. This dynamic absorber is designed based on an analysis of the free vibration of the engine shafting system and the forced vibrations.

• Journal of the Society of Naval Architects of Korea
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• v.31 no.4
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• pp.157-166
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• 1994

Recently. the excessive diesel engine torsional excitation of typical energy saving ships has resulted in severe damages of the propeller shaft. Up to now the design and torsional vibration analysis of the marine diesel shafting system has been performed on the assumption that excitations are deterministic. But a diesel engine excitation varies randomly from cylinder to cylinder and from cycle to cycle, due to the imperfect operation of the engine components due to engine misfiring. consequently, a more rational analysis method for the propulsion shafting torsional vibration is required. In this paper probabilistic analysis method of the marine diesel engine shafting system under torsional vibration is presented. First a response surface representing maximum shear stresses in a shafting system is built. Then Monte Carlo simulation with subsequent approximation of the results by one of Pearson's curves, is performed. Some numerical results based on the proposed method are compared with t도 some numerical data available. They show acceptable agreements with the data.

• Journal of the Society of Naval Architects of Korea
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• v.35 no.3
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• pp.71-78
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• 1998

Recently, modern long-stroke diesel engines with small number of cylinders have been installed for energy saving and simpler maintenance. These kinds of low speed diesel engine produce large torsional vibration in the shafting, which induces the excessive vibratory stresses in the shafting and large propeller thrust variation. This thrust variation excites vibrations of the shafting and superstructure in the longitudinal direction. Up to now the deteriministic analysis of coupled vibration of marine shafting system has been performed. In this paper probabilistic analysis method of the marine diesel propulsion shafting system under coupled axial and torsional vibrations is presented. For the purpose of this work, the torsional and axial vibration excitations of engine and propeller are assumed to be probabilistic while the lateral excitation is assumed to be deterministic. The probabilistic analysis is based on a response surface and Monte-Carlo simulation. Numerical results based on the proposed method are compared with results calculated using the conventional deterministic analysis method. The results obtained make it clear that the proposed method gives a substantial increase in information about shafting behaviour as compared with the deterministic method.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.40 no.3
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• pp.232-243
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• 2004

After studying the composition about the torsional shafting of main engine for fishing vessel with Power Take Off (PTO) System, the authors made a computer program using the transfer stiffness coefficient method (TSCM) for analyzing torsional vibration about the shafting with PTO system and nonlinear elastic coupling. The torsional shafting of main engine was separated by 3 types according to the connecting. The torsional shafting of main engine was separated by 3 types according to the connecting condition of main engine with propeller or the PTO system or both of them. In this paper, the change of natural frequencies and natural modes according to connecting condition of torsional shafting and nonlinear elastic coupling were analyzed. The accuracy of the TSCM was confirmed by comparing with the computational results of the Finite Element Method.

• Journal of Advanced Marine Engineering and Technology
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• v.22 no.3
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• pp.328-336
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• 1998

Marine reduction gears are usually used to increase the propulsion efficiency of propellers for ships powered by medium and small sized high speed diesel engines. Most of shaft systems adopt flexible couplings to absorb the transmitted vibratory torque from the engines to the reduction gears and to prevent the chattering phenomenon of reduction gears. However some elastic couplings show non-linear characteristics due to the variable torque transmitted from the main engines and the change of ambient temperature. In this study dynamic characteristics of flexible couplings sare investigated and their effects upon various vibratory conditions of propulsion systems are clarified. A calculation program of torsional vibration for the propulsion systems are clarified. A calculation program of Results of the program developed are compared with ones of the existing linear method and propulsion systems with the elastic couplings the transfer matrix method is adopted which is found to give satisfied results.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.23 no.1
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• pp.25-29
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• 1987

The engine room of ship is a synthetic system being composed of many machineries. Therefore, the reliability and safety of the all system of machinery is as important as each machine. In this paper, in order to reudce engine troubles while operation and to contribute in developing a high reliable marine engine the author analysed the factors of marine engine troubles by principal com-ponent analysis method. Analysed data are marine engine troubles of sea casualties from 1980 to 1985. It is found that the major part of marine engine troubles resulted from personal mistake, and also the troubles of shaft, propeller and cylinder occupied considerable proportion.

• Special Issue of the Society of Naval Architects of Korea
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• 2008.09a
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• pp.54-61
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• 2008

With the development of computer program in calculation for torsional vibration of ship's propulsion shafting it has become possible to calculate all order's vibratory amplitude, vibratory torque, vibratory stress and synthesis value at all concerned revolutions by way of solving the vibratory equation directly. Though this kind of propulsion shafting vibration calculation method makes it possible to get generalized and precise result of calculation, the unexpected critical crankshaft torsional vibration has still appeared in maneuvering range of the engine. A close investigation has been carried out to find out the cause for the 2-node propulsion shafting torsional vibration of the crankshaft that exceeded the limitation value near the MCR 104rpm on the sea trial of the recently delivered 6000TEU class container vessel from HHIC. In conclusion, as the latest super-output engine with heavy crankshaft and propeller mass seems to be liable to 2-node torsional vibration of crankshaft, it is recommend that, in the design stage of propulsion shafting, its torsional vibration condition must be more carefully checked.