• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2005.05a
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• pp.192-195
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• 2005

In this study, dynamic characteristics of an end-capped hull structure with surface bonded piezoelectric actuators are studied. Finite element modeling is used to obtain practical governing equation of motion and boundary conditions of smart hull structure. Modal analysis is conducted to investigate the dynamic characteristics of the hull structure. Piezoelectric actuators are attached where the maximum control performance can be obtained. Active controller based on Linear Quadratic Gaussian (LQG) theory is designed to suppress vibration of smart hull structure. It is observed that closed loop damping can be improved with suitable weighting factors in the developed LQG controller.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2011.04a
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• pp.273-278
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• 2011

This work presents an active vibration control of a stiffened hull structure using a flexible macro fiber composite (MFC) actuator. As first step, the governing equation of the hull structure is derived in a matrix form and its dynamic characteristics such as natural frequency are obtained via a finite element analysis (FEA). The natural frequencies obtained from the FEA are compared with those determined from experimental measurement. After formulating the control model in a state space representation, an optimal controller is designed in order to attenuate the vibration of the stiffened hull structure. The controller is then empirically realized through dSPACE and control responses are evaluated in time domain.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.21 no.7
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• pp.643-649
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• 2011

This work presents an active vibration control of a stiffened hull structure using a flexible macro fiber composite(MFC) actuator. As first step, the governing equation of the hull structure is derived in a matrix form and its dynamic characteristics such as natural frequency are obtained via a finite element analysis(FEA). The natural frequencies obtained from the FEA are compared with those determined from experimental measurement. After formulating the control model in a state space representation, an optimal controller is designed in order to attenuate the vibration of the stiffened hull structure. The controller is then empirically realized through dSPACE and control responses are evaluated in time domain.

• The Journal of the Korea institute of electronic communication sciences
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• v.6 no.1
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• pp.123-128
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• 2011

Hull design for a small scale Oceanographic buoy will be introduced in this paper. The hull structure design, the connection methods between all parts will be discussed. We mainly introduce a design process of this buoy hull. We use walls with two layers and a radial bone structure to support the body to increase overall intensity and capacity to resist impact.

• Journal of Ship and Ocean Technology
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• v.10 no.4
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• pp.24-33
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• 2006

So far, the generation of a hull structural analysis model, that is, a finite element model of a hull structure, has been manually performed by a designer using design experience, and thus has required lots of time because of many constraints, the complexity, and the huge size of the hull structure. To make this task automatic, an algorithm for generating the hull structural analysis model is developed using the seam information of the hull structure. A generating system of the hull structural analysis model is implemented based on the developed algorithm. The applicability of the developed algorithm is demonstrated by applying it to the generation of the global and hold structural analysis models of a deadweight 300,000 ton VLCC (Very Large Crude oil Carrier). The results show that the developed algorithm can quickly generate these models at the initial design stage.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.15 no.12 s.105
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• pp.1408-1415
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• 2005

Active vibration control of smart hull structure using Macro Fiber Composite (MFC) actuator is performed. Finite element modeling is used to obtain governing equations of motion and boundary effects of end-capped smart hull structure. Equivalent interdigitated electrode model is developed to obtain piezoelectric couplings of MFC actuator. Modal analysis is conducted to investigate the dynamic characteristics of the hull structure, and compared to the results of experimental investigation. MFC actuators are attached where the maximum control performance can be obtained. Active controller based on Linear Quadratic Gaussian (LQG) theory is designed to suppress vibration of smart hull structure. It is observed that closed loop damping can be improved with suitable weighting factors in the developed LQG controller and structural vibration is controlled effectively.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2005.11a
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• pp.217-222
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• 2005

Active vibration control of smart hull structure using Macro Fiber Composite (MFC) actuator is performed. Finite element modeling is used to obtain governing equations of motion and boundary effects of end-capped smart hull structure. Equivalent interdigitated electrode model is developed to obtain piezoelectric couplings of MFC actuator. Modal analysis is conducted to investigate the dynamic characteristics of the hull structure, and compared to the results of experimental investigation. MFC actuators are attached where the maximum control performance can be obtained. Active controller based on Linear Quadratic Gaussian (LQG) theory is designed to suppress vibration of smart hull structure. It is observed that closed loop damping can be improved with suitable weighting factors in the developed LQG controller and structural vibration is controlled effectively.

• Journal of Ship and Ocean Technology
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• v.5 no.4
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• pp.19-28
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• 2001

A comparative study of the new flexible double hull structure is presented as a collision energy absorbing system, which is constructed with mixed stringers comprising slant and straight stringers for the double hull tanker, The dimension and disposition of this mixed stringers are selected to give the maximum absorbing energy. From the viewpoint of collision energy absorbing efficiency, this structural system is compared with three other types of the double hull constructions with trapezoidal stiffener, stringer type and standard type of VLCC, 310K DWT, Based on the constant hull weight, the proposed double hull structure with mixed stringers shows a improved crashworthiness as the results.

• Journal of Korean Society for Quality Management
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• v.45 no.3
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• pp.393-401
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• 2017

Purpose: The purpose of this study is to propose retrofit measures for KDX-II KVLS hull crack, also, enhance safety and quality of ship. Also, this study suggest to how to retrofit about hull crack of the ship and how to improve operability of the ship. Methods: Retrofit measures of KDX-II KVLS hull crack reach a conclusion through global structure analysis and fatigue analysis. Concerned about thermal deformation due to welding around the KVLS, in addition to, verify to safety of KVLS. Results: Based on result of global structure analysis establish retrofit measures for KDX-II KVLS hull crack. Additionally, through fatigue analysis establish final retrofit measures. The results of retrofit measures are allowed both stress level and fatigue life. Conclusion: Retrofit measures for ship hull crack based on global structure analysis and fatigue analysis improves operability and quality of the ship. Especially, KDX-II ship is the best battleship in our country. Considering the importance of KDX-II, this study improves both Korea navy's combat power and ability to carry out the mission.

• Journal of the Society of Naval Architects of Korea
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• v.56 no.3
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• pp.187-199
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• 2019

In the case of gas carriers and oil tankers, pipes are installed on the upper deck as a moving passage to load LPG, LNG, crude oil, etc. Pipes used for loading or unloading liquid cargo in cargo holds are connected to the hull through support structures. However, many cases of hull damage have been reported where the various equipment and support structures are installed on the upper deck. It is assumed that not only the structural discontinuity where the hull and the pipe support structure meet, but also action due to the pipe loads and the hull girder bending moment are simultaneously affected. This paper deals with the design and strength evaluation of the support structure of pipes and cables installed on the upper deck of commercial ships and offshore structures. For these supporting structures, design conditions and working loads were defined. The design procedure was established through the structure analysis on the method of determining the member dimensions. A series of finite element analysis was performed on the factors to be considered in the design and the effects were discussed. The accuracy and design periods of the strength evaluation was improved and reduced by application of the automation program in the finite element analysis. It is also expected that the design reliability of the shipyard is improved.