• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.21 no.8
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• pp.761-767
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• 2011

Free and forced vibration analysis of the global ship structure using the 3-dimensional finite element(FE) method requires not only the specialized knowledge such as ship structure interacted with fluid, damping and various excitations due to propulsion system but also time-consuming manual tasks in FE modeling, analysis and response evaluation. As a result, the quality of the vibration analysis highly depends on engineer's expertise and experience. In this study, a framework system to improve the efficiency of global ship vibration analysis is introduced. The system promising the utilization of MSC/Patran and MSC/Nastran consists of various modules to support data management, FE modeling of ship structure and loading, input deck generation for free and forced vibration analysis, data extraction and evaluation of analysis results, and databases for FE models of marine diesel engines and vibration criteria. The system may be useful for pursuing standardization of uncertain analysis factors as well as reducing time, cost and human dependency in ship vibration analysis.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2011.04a
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• pp.779-784
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• 2011

Free and forced vibration analysis of the global ship structure using the 3-dimensional finite element(FE) method requires not only the specialized knowledge such as ship structure interacted with fluid, damping and various excitations due to propulsion system but also time-consuming manual tasks in FE modeling, analysis and response evaluation. As a result, the quality of the vibration analysis highly depends on engineer's expertise and experience. In this study, a framework system to improve the efficiency of global ship vibration analysis is introduced. The system promising the utilization of MSC/Patran and MSC/Nastran consists of various modules to support data management, FE modeling of ship structure and loading, input deck generation for free and forced vibration analysis, data extraction and evaluation of analysis results, and databases for FE models of marine diesel engines and vibration criteria. The system may be useful for pursuing standardization of uncertain analysis factors as well as reducing time, cost and human dependency in ship vibration analysis.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.26 no.5
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• pp.528-535
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• 2016

The vibration of a ship gives a significant effect on the noise radiated into the water. This paper focused on the vibration of ship hull due to the sub-generator located on the deck in the anchored condition. The contributions of the transfer paths between sub-generator and ship hull were analyzed using the TPA and the OTPA method. While the sub-generator was operation and the main engine was turned off, the vibrations were measured simultaneously at the 38 locations of the ship and the one hydrophone was arranged to measure the underwater radiated noise at the overside ship. The results of the transfer path by applying TPA and OTPA were compared and discussed. As a result of these methods, the top of stovepipe and valve are contributive. Reinforcing these structures is the most effective to reduce the vibration of ship hull.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2008.04a
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• pp.368-372
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• 2008

Habitability is one of the most important points when a passenger ship is cruising. In particular, anti-vibration design should be considered preferentially to offer passenger a comfort cabin and leisure space. But, a passenger ship is different from a general commercial ship in the view point of the structural arrangement. It is restricted within narrow limits to reinforce wide panels and local structures of a passenger ship because of its interior design. Moreover, the allowable vibratory limits for a passenger ship are much lower than those of a commercial ship. In this study are introduced the procedure of the vibration analysis, the structural improvement method for prevention of vibration and the results of vibration measurement during exciter test and sea trials.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.18 no.1
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• pp.35-38
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• 1982

Ship hull Vibration is caused by troubling measure instruments installed in the ship, fatigue of the hull girder. Vibration has been studied by the View point of anti-Vibration. However, the theoretical calculation values of the Vibration analysis were not obtained accurately. Therfore, in this paper, Vibration analysis were made on the two (cylinder form, ship form) of ship hull girder by the transfer matrix method. The super-structure length was determined to be 0, 20, 40, 60, 80, 100, percentage of the ship's length from the stern. The results of analysis by the transfer matrix method are as follow. 1. Natural frequency may be determined by the order of node numbers and superstructure length. 2. Natural frequency inereased when the ship form is a finess and increasing ratio followed by high order of node numbers.

• International Journal of Ocean System Engineering
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• v.1 no.2
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• pp.76-88
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• 2011

The present study deals with the hydroelastic vibration analysis of structures in contact with fluid via coupled fluid-structure interaction (FSI) embedded with a finite element method (FEM) such that a structure displacement formulation is coupled with a fluid pressure-displacement formulation. For the preliminary study and validation of FEM based coupled FSI analysis, hydroelastic vibration characteristics of a rectangular plate in contact with fluid are first compared with the elastic vibration in terms of boundary condition and mode frequency. Numerical results from coupled FSI analysis have been shown to be rational and accurate, compared to energy method based theoretical solutions and experimental results. The effect of free surface on the vibration mode is numerically studied by changing the submerged depth of a rectangular plate. As a practical application, the hull structural vibration of 4,000 twenty-foot equivalent units (TEU) container ship is considered. Hydroelastic results of the ship hull structure are compared with those obtained from the elastic condition.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2005.11b
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• pp.81-84
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• 2005

A passenger ship has some differences compared with a general commercial ship from the viewpoint of the structural arrangement. It is difficult to reinforce wide panels and local structures of a passenger ship because of its interior design when they have vibration problems. Moreover, the allowable vibratory limit for a passenger ship is much lower than that of a commercial ship. In this study, it is introduced that the procedure of the vibration analysis and the structural improvement for prevention of vibration with consideration of interior design for the Atrium stairway, one of the local structure installed in public space.

• Journal of the Society of Naval Architects of Korea
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• v.48 no.4
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• pp.368-374
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• 2011

Recently, the ship vibration analysis technique has been well set up by using FEM. The methods considering the hydrodynamic added mass and damping of the fluid surrounding a floating ship have been well developed, so that they can be calculated by using the commercial package FEM programs such as MSC/NASTRAN, ADINA and ANSYS. Especially, MSC/NASTRAN has the functions to consider the fluid in tanks(MFLUID) and to solve the Fluid-Structure Interaction(FSI) problem(DMAP). In this study, the global ship vibration with considering the added mass distributed at the grid points on the wetted shell surface is introduced to. In the new method, the velocity potentials of the fluid surrounding a floating ship are calculated by solving the Lapalce equation using the Boundary Element Method(BEM), and the point mass is obtained by integrating the potentials at the points. Then, the global vibration analyses of the ship structure with distributed added mass on the wetted surface are carried out for an oil/chemical tanker. During the future sea trial, the results will be confirmed by measurement.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2004.05a
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• pp.433-437
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• 2004

A provision crane is generally installed on the upper deck to the rear of the accommodation of the ship in order to load and unload engine part or something heavy. There are two types of provision cranes: one is jib-type and the other is monorail-type. So the natural frequency of the jib-type crane equipment is low, therefore, there are some possibility of resonance between crane structure and the main excitation sources of the ship in normal operating range. This study describe a vibration reduction technique for provision crane by applying a proper countermeasure through finite element analysis and modal test. In order to find out weak point in design of provision crane, a sensitive analysis has been performed.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2008.11a
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• pp.329-330
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• 2008

The 181,000 DWT Bulk Carrier has a different deck house type, which is not typical for previous bulk carriers, to meet the new international rules for bulk carriers. This new deck house has much smaller transverse breadth than the hull's transverse breath, resulting in large levels of the transverse response of the deck house. In addition, the longitudinal response of the funnel showed rather a large magnitude of vibration, which are excited by the ship's main excitations such as the main engine H-moment and the propeller surface forte when the ship operates at the NCR and the MCR speeds In the ballast condition. To solve these issues, the global forced vibration analysis has been performed for the ship and the ship structure has been modified to reduce the vibration level by increasing the girder depth and adjusting the engine room tank arrangement.