• 선박안전
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• 제7권
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• pp.13-26
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• 2001

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2009년도 추계학술대회 논문집
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• pp.248-253
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• 2009

The propulsion system which apply the diesel engine with reduction gear as prime mover, generally installs the elastic coupling between engine and intermediate shaft, This coupling can isolate the vibratory torque excited by diesel engine, or the excess transient torque and moment occurring by external impact. So, diesel engine and reduction gear can safely operate by elastic coupling. Unfortunately, the elastic coupling for skimmer vessel was repeatedly broken by unknown vibration during the sea trial In this paper, the authors are searching for the possibilities and causes of the elastic coupling failure, via the global vibration measurement and the past incident investigation.

• 한국항해항만학회:학술대회논문집
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• 한국항해항만학회 2010년도 춘계학술대회
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• pp.297-298
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• 2010

선박 추진축계의 동력을 계측하기 위해서는 일반적으로 스트레인 게이지를 이용한 방법이 널리 사용된다. 이러한 방법의 경우 스트레인 게이지 외에도 많은 부품들을 축에 장착해야 하며 전원을 공급하기 위해 별도의 장치를 필요로 하는 등 설치 시 매우 복잡하고 섬세한 작업이 요구된다, 뿐만 아니라 계측신호를 취득하고 분석하기 위해서도 고도의 전문성이 요구되기 때문에 운전 중의 실시간 계측을 통한 모니터링 목적이 아니라 시험 및 검증을 위해 사용될 뿐이다. 따라서 본 연구에서는 이와 같은 단점들을 보완하면서도 추진축계의 동력을 비교적 용이하게 계측하기 위한 새로운 방법을 제안하고자 한다. 본 연구에서 제안하는 계측기법은 카메라를 사용하여 축동력을 계측하는 방법으로 실험결과를 통해 유효성을 확인하였으며 항해 중 실시간 모니터링이 가능한 감시 시스템을 구축할 수 있는 새로운 계측기술이라 할 수 있다.

• Journal of Advanced Marine Engineering and Technology
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• 제33권1호
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• pp.28-36
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• 2009

In this paper, based on the measured data of hull deflection, an approximated hull deflection curve is drawn using reverse analyzed hull deflection data and the estimation method for flexibility analysis of shaft alignment is proposed by use of the approximate hull deflection curve. Generally an offset value of after stern tube bearing is a datum point with an fore stern tube bearing however the shaft alignment has a tendency which is able to get higher flexibility if the shafting system has the deflection value from after stern tube bearing as reference to bottom direction according to results of on this study. By applying this result of study, the shaft alignment for next similar ships will be able to estimate how to follow the hull deflection and how to be influenced by hull deflection at shaft alignment analysis state using the approximated hull deflection curve.

• Journal of Advanced Marine Engineering and Technology
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• 제25권1호
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• pp.95-106
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• 2001

When the crankshaft of diesel engine has more than 3 throws, which are arranged in a different plane, its vibration induces coupled motions, especially the coupled torsional and axial vibration. Nowadays, the torsional vibration which is influenced rather weak than axial one, can be theoretically calculated fairly accurately, but theoretical calculation results of the axial vibration which is influenced strongly from torsional vibration is not so good. To get accurate calculation results of axial vibration, coupled axial-torsional vibration must be treated. In this investigation, coupled effects of vibration of diesel engine propulsion shafting are analyzed theoretically and some simple calculation methods are also studied. On this first report, effects of coupling on natural frequencies and their modes are mainly studied, setting the each mass in 4 degrees of freedom.

• 한국유체기계학회 논문집
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• 제2권2호
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• pp.39-45
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• 1999

Pumped-storage power plants pumps the water from the lower reservoir to the upper reservoir using the extra electric power at night and generates electric power in the daytime. Currently it tends to be a high-head large-capacity machine. In this paper, we developed the computer programs for vibration analysis of the pump/turbine and generator/motor rotor system considering electromagnetic force, hydrodynamic unbalance force, dynamic characteristics of guide bearings and add mass of water. This program was verified by applying it to the real model and calculating the critical speed, natural mode and unbalance response.

• 동력기계공학회지
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• 제16권2호
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• pp.11-16
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• 2012

In this paper, the authors formulate the sensitivity analysis algorithm for the natural frequency of a torsional shafting by expanding the transfer stiffness coefficient method. The basic concept of the present algorithm is based on the transfer of sensitivity stiffness coefficient, which is the derivative of stiffness coefficient with respect to design parameter, at every node from the first node to the last node in analytical model. The effectiveness of the present algorithm is confirmed by comparing the results of the sensitivity analysis and those of the reanalysis for the natural frequencies of a torsional shafting with a constant cross section. In numerical calculation, the design parameter is the diameter of the shaft element of the torsional shafting.

• Journal of Advanced Marine Engineering and Technology
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• 제22권3호
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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.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2007년도 춘계학술대회논문집
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• pp.416-422
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• 2007

Prime movers in most large merchant ships adapt two stroke low speed diesel engine which has higher efficiency, mobility and durability. However, severe torsional vibration in these diesel engines may be induced by higher fluctuation of combustion pressures. Consequently, it may lead sometimes to propulsion shafting failure due to the accumulated fatigue stresses. Shaft fatigue strength analysis had been done traditionally in time domain but this method is complicated and difficult in analysing bi-modal vibration system such as the case of cylinder misfiring condition. In this paper authors introduce an assessment method of fatigue strength estimation for propulsion shafting system with two stroke low speed diesel engine in the frequency domain.

• 한국마린엔지니어링학회:학술대회논문집
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• 한국마린엔지니어링학회 2005년도 후기학술대회논문집
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• pp.3-4
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• 2005

With an increase in the size and power rate of ship, the stern tube bearing has become subject to severer operation conditions. Particularly it is expected to be exposed to extremely so severe lubrication conditions during low rotational operation that there is strong demand for clarifying the oil film characteristics of the stern tube bearing at the design stage with accuracy. So in this study, we conducted an analysis of the stern tube bearing characteristics taking arbitrary three-dimensional deflection of the shaft into consideration.