• International Journal of Naval Architecture and Ocean Engineering
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• v.6 no.3
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• pp.652-669
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• 2014

This paper concerns the kinematic characteristics of a coupling device in a deep-seabed mining system. This coupling device connects the buffer system and the flexible pipe. The motion of the buffer system, flexible pipe and mining robot are affected by the coupling device. So the coupling device should be considered as a major factor when this device is designed. Therefore, we find a stable kinematic device, and apply it to the design coupling device through this study. The kinematic characteristics of the coupling device are analyzed by multi-body dynamics simulation method, and finite element method. The dynamic analysis model was built in the commercial software DAFUL. The Fluid Structure Interaction (FSI) method is applied to build the deep-seabed environment. Hydrodynamic force and moment are applied in the dynamic model for the FSI method. The loads and deformation of flexible pipe are estimated for analysis results of the kinematic characteristics.

• Journal of Ocean Engineering and Technology
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• v.22 no.1
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• pp.22-29
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• 2008

A numerical investigation is made on the effects of the location and shape of the front wall of an OWC(Oscillating Water Column) chamber on the hydroelastic response of a VLFS. Most of the studies on the effects of an OWC chamber on the response of a VLFS have assumed the location of the OWC chamber to be at the front of the VLFS. In the present study, an OWC-chamber is introduced at an arbitrary position in relation to a VLFS to determine the influence of the location and shape of the OWC chamber on the hydroelastic response of the VLFS. A finite element method is adopted as a numerical scheme for the fluid domain. or the finite element method, combined with a mode superposition method, is applied in order to consider the change of mass and stiffness The OWC chamber in a piecewise constant manner. or the facilitated anefficient analysis of The hydroelastic response of the VLFS, as well as the easy modeling of different shape and material properties for the structure. Reduction of hydroelastic response of the VLFS is investigated for various locations and front wall shapes of the owe chamber.

• Journal of Korea Technology Innovation Society
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• v.17 no.2
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• pp.355-379
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• 2014

For the transition to the low carbon society, it is inevitable but difficult journey that the new energy technology spread co-exists with formal social system. The objective of offshore wind power plant that has been implemented by the government is to connect large capacity new renewable energy to the central electric power system. Therefore, for the successful introduction of offshore wind power system, the transition of the formal social technology system should be companied. This study analysis the energy system transition about niche strategy adjustment using Multiple Level Perspectives & Strategic Niche Management. It also multi level analyzes and structuralizes the process that new technology, as a research result, evolves through connecting and communicating with formal regime and landscape. Also, adjusting Strategic Niche Management, it diagnoses the obstructive factors in the initial stage of niche experiment and found the major reasons why offshore wind power test plant had been delayed. Through this study, it reaches to the practical implication that offshore niche technology could grow stably in the energy system and various policies.

• Journal of the Economic Geographical Society of Korea
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• v.20 no.1
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• pp.16-33
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• 2017

This study analyzed the actual condition of the purchasing and selling network structures of manufacturing firms related the shipbuilding and offshore plant industry in Jeollanam-do using the social network analysis. The analysis results are as follows. The networks are often traded by subcontracting relationship with large firms because the industry is configured in most small and medium-sized firms. In particular, it was found to actual situation that selling transactions are being concentrated in the manufacturing firms of Yeongnam where large firms have located. Structural adjustment of the large firms located in the Yeongnam is expected to strike a blow to the manufacturing firms related the shipbuilding and offshore plant industry in Jeollanam-do due to the recently crisis in the shipbuilding industry. Therefore, it is necessary to secure a diversity of networks for selling transactions, and to discover and promote that selling firms related the shipbuilding and offshore plant industry in Jeollanam-do, in order to cope with such a crisis.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2019.11a
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• pp.150-152
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• 2019

In this study, the effects of the wave field changes due to the coastal structure on the hydrodynamic performance of the OWC wave energy, converter are analyzed using a three-dimensional numerical wave tank technique (NWT). The OWC device is simulated numerically by introducing a linear pressure drop model, considering the coupling effect between the turbine and the OWC chamber in the time domain. The flow distribution around the chamber is different due to the change of reflection characteristics depending on the consideration of the breakwater model. The wave energy captured from the breakwater is spatially distributed on the plane of the front of the breakwater, and the converted pneumatic power increased when concentrated in front of the chamber. The change of the standing wave distribution is repeated according to the relationship between the incident wavelength and the length of the breakwater, and the difference in energy conversion performance of the OWC was confirmed.

• Journal of the Korean Society for Marine Environment & Energy
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• v.20 no.1
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• pp.26-36
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• 2017

Korea is preparing an offshore carbon capture, transport and storage (CCS) demonstration project which is recognized as one of important $CO_2$ reduction technologies to mitigate climate change. The offshore CCS project aims to transport, inject and store large amount of $CO_2$ into offshore geologic formation, and has a potential risk of leakage which might cause disastrous damage to human health, environment and property. Therefore, in order to ensure the safety of the offshore CCS project, a strict HSE (health, safety and environment) management plan and its implementation are required throughout the project life cycle. However, there are no HSE domestic laws or regulations applicable to CCS projects, and the related research is insufficient in Korea. For the derivation of the essential and urgent requirement in HSE management framework applicable to the offshore CCS project in Korea, we analysed the HSE management methodologies and foreign CCS HSE management guidelines and cases. First, this paper has analyzed ISO 31000, a generalized risk management principles. Second, we have investigated the HSE management practices of CCS projects in Norway and UK. Based on the analyses, we suggested the necessity of developing the HSE Philosophy and the HSE management process through the whole life cycle. Application of HSE management in early phase of an offshore CCS project will promote systematic and successful project implementation in a cost-effective and safe way.

• Journal of computational fluids engineering
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• v.21 no.4
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• pp.78-84
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• 2016

In this paper, turbulence models for considering roughness in the open source code(OpenFOAM) was investigated. Wall function in the RANS(Reynolds-averaged Navier - Stokes) turbulence model was modified considering roughness on the flat plate by using roughness function. Correlation between the first layer height in the CFD model and roughness height of the plate was observed, and the most proper roughness function, and the first layer height from the plate wall in the CFD analysis was suggested in this paper.

• Journal of Ocean Engineering and Technology
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• v.26 no.6
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• pp.7-13
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• 2012

This paper presents a numerical study of the wave loads acting on offshore structures using a Cartesian-grid-based flow simulation method. Finite volume discretization with a volume-of-fluid (VOF) method is adopted to solve two-phase Navier-Stokes equations. Among the many variations of the VOF method, the CICSAM scheme is applied. The body boundary conditions are satisfied using a porosity function, and wave generation is carried out by using transient (wave or damping) zone approaches. In order to validate the present numerical method, three different basic offshore structures, including a sphere, Pinkster barge, and Wigley model, are numerically investigated. First, diffraction and radiation problems are solved using the present numerical method. The wave exciting and drift forces from the diffraction problems are compared with potential-based solutions. The added mass and wave damping forces from the radiation problems are also compared with the potential results. Next, the wave-induced motion responses of the structures are calculated and compared with the existing experimental data. The comparison results are fairly good, showing the validity of the present numerical method.

• Journal of the Society of Disaster Information
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• v.10 no.2
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• pp.244-252
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• 2014

In this study, seismic responses of the offshore wind tower supported by bucket foundation are analyzed in consideration of soil-structure interaction. The program SASSI is used as analyzing tool and an artificial seismic input for soft soil is used as input motion. The H/R ratio of bucket, the stiffness of bucket foundation and the soil stiffness are considered as parameters and its effects are estimated. The responses of structure are obtained at the base and the nacell. As results, the effects of H/R ratio, the stiffness of bucket and the stiffness of site are generally denoted different response tendency at the base and the nacell. However, these whole responses of the base and the nacell are much lager than that of rock site. Therefore, the consideration of this phemomia affect to the response of offshore wind tower with bucket foundation largely.

• Journal of Ocean Engineering and Technology
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• v.27 no.5
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• pp.63-69
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• 2013

The mooring lines of a floating type offshore plant are known to show wide banded and bimodal responses. These phenomena come from a combination of low and high frequency random load components, which are derived from the drift-restoring motion characteristic and wind- sea, respectively. In this study, fatigue models were applied to predict the fatigue damage of mooring lines under those loads, and the result were compared. For this purpose, seven different fatigue damage prediction models were reviewed, including mathematical formula. A FPSO (floating, production, storage, and offloading) with a $4{\times}4$ spread catenary mooring system was selected as a numerical model, which was already installed at an offshore area of West Africa. Four load cases with different combinations of wave and wind spectra were considered, and the fatigue damage to each mooring line was estimated. The rain flow fatigue damage for the time process of the mooring tension response was compared with the results estimated by all the fatigue damage prediction models. The results showed that both Benasciutti-Tovo and JB models could most accurately predict wide banded bimodal fatigue damage to a mooring system.