Sharing piping CAD models of ocean plants based on international standards

In the shipbuilding industry, different computer-aided design (CAD) systems are used for different design domains, structure, and outfitting. We need to exchange data among different CAD systems such as Tribon, AutoCAD, Intergraph or PDMS to complete the whole design and production process. There are two approaches to data exchange. One is direct translation; the other is indirect translation, which is based on a neutral format. If we use a neutral format, the data specification is open to the public and the design model can be used by other CAD systems, including next-generation CAD systems. In this paper, we propose an indirect method that uses ISO 10303 (STandard for the Exchange of Product model data) AP227 and ISO 15926 to define neutral formats. A separate ShapeDB is constructed to manage the geometry information, referenced to the catalogue data defined by ISO 15926. An experimental implementation for data exchange between Tribon and PDMS is described.     

Public preference for the attributes of the marina port in Korea: a choice experiment study

As of late, the Korean government needs quantitative information on economic feasibility analysis for marina port development projects. This study applies a choice experiment to measure public preference for the attributes of marina port in Korea. We consider the trade-offs between price and four attributes of marina port (capacity, access, waterfront, and program) for selecting a preferred alternative and elicit the marginal willingness to pay (MWTP) estimates for each attribute. We also test whether irrelevant alternatives property for the estimation model holds and compare the estimation results of the multinomial logit (MNL) and the nested logit (NL) models. The results show that the NL model outperforms the MNL model. In the NL model, MWTPs for increasing the level of a waterfront from promenade to both promenade and rest area and for the provision of marine leisure experience program are KRW13 384 (USD11.8) and KRW17 937 (USD15.8), respectively. This study is expected to provide policymakers with quantitative information for evaluating marina port construction projects in Korea.     

Computational investigation of cavitation on a semi-spade rudder

This article examines noncavitating and cavitating flow fields around a semi-spade rudder in the ship wake and propeller slipstream based on a computational method. The article seeks to explain the erosion that can occur around the gap due to cavitation; such erosion has been reported to occur while a ship is at sea. Another area of research is the effect of the gap size and shape. The effects of erosion-evading devices such as elongated gap edges, an increased edge radius, flow control projections, and vertical and horizontal guide plates were also studied.     

A process-centric ship design management framework

As the concept of concurrent engineering has emerged along with support for optimization techniques, lots of endeavors have been made to apply optimization techniques to real design problems for holistic decision-making. Even if the range of design problems to which optimization is applicable has been extended, most ship designs use an iterative and manual approach due to the difficulties of seamless integration of all related design activities. This paper proposes a process-centric management framework for the preliminary ship design process depending on these approaches. Requirements for the framework are generated based on the features of the ship design process first. The proposed framework consists of both process scheduling and process management parts. Each of these modules is divided into submodules, and the modules and their interactions are elaborated to reflect actual design practice. The designed framework is embodied within a workflow system and its usefulness examined through a pilot project.     

Steady streaming of viscous surface layer in waves

An investigation of the drift velocity induced by water waves of a contminated surface layer is carried out. The theoretical analysis is based on a thin boundary layer on the free surface. The results of the analysis reveal that the drift velocity of a viscous layer on the water surface is 7/4 times the Stokes prediction ofc(ak) ² wherec is the wave celerity andak the wave slope. The present experimental investigation confirms the validity of the theoretical prediction for the drift velocity for a lightly contaminated surface layer; however, for a heavily contaminated surface layer, the experimental results exceed the theoretical prediction. An investigation for a heavily contaminated layer is carried out assuming an inextensible surface layer. Thus, in the experiment, vinyl sheets are used to substitute the contaminated layers. By balancing the wave-induced mean thrust force with the mean drag force, the drift velocity is obtained and compared with the experimental results. Based on the theoretical and experimental analyses, formulae for predicting the drift velocities for laminar and turbulent flow conditions are proposed.     

Optimal scheduling of block lifting in consideration of the minimization of traveling distance while unloaded and wire and shackle replacement of a gantry crane

Nowadays, shipyards are making every effort to efficiently manage their resources such as gantry cranes, transporters, and block stock yards. The scheduling of block lifting for a gantry crane has been manually performed by an expert shipyard manager for many years. Such a practice, however, can lead to an undesirably long time to produce scheduling plans. In addition, the quality of the scheduling plans may not be optimal. To improve the overall process, a block lifting scheduling system for a gantry crane was developed in this study by using optimization techniques. A block lifting scheduling problem was first formulated as a multiobjective optimization problem. For a gantry crane, minimization of the traveling distance while unloaded and wire and shackle replacement between block lifting was considered. An optimization algorithm based on the genetic algorithm was then proposed and implemented so as to solve the problem. To evaluate the efficiency and applicability of the developed system, the system was applied to an actual block lifting scheduling problem in a shipyard. Compared to results achieved by manual scheduling by an expert manager, the results of this work show that blocks can be more efficiently lifted by a gantry crane when the developed system is applied.     

Comparison of computational and analytical methods for evaluation of failure pressure of subsea pipelines containing internal and external corrosions

In the designing stage of subsea pipelines, the design parameters, such as pipe materials, thickness and diameters, are carefully determined to guarantee flow assurance and structural safety. However, once corrosion occurs in pipelines, the operating pressure should be decreased to prevent the failure of pipelines. Otherwise, an abrupt burst can occur in the corroded region of the pipeline, and it leads to serious disasters in the environment and financial loss. Accordingly, the relationship between the corrosion amount and failure pressure of the pipeline, i.e., the maximum operating pressure, should be investigated, and then, the assessment guideline considering the failure pressure should be identified. There are several explicit type codes that regulate the structural safety for corroded subsea pipelines, such as ASME B31G, DNV RF 101, ABS Building and Classing Subsea Pipeline Systems, and API 579. These rules are well defined; however, there are some limitations associated with describing precise failure pressure. Briefly, all of the existing rules cannot consider the material nonlinearity, such as elastoplasticity effect of the pipeline, as well as the actual three-dimensional corrosion shape. Therefore, the primary aim of this study is to suggest a modified formula parameter considering the above-mentioned pipeline and corrosion characteristics. As a result, the material nonlinearity as well as the corrosion configuration, i.e., axial/circumferential corrosion length, width and depth, is reflected in a set of finite element models and a series of finite element analysis considering the operation conditions are followed. Based on the comparative study between the simulation and analytical results, which can be obtained from the classification society rules, the modified formulae for failure pressure calculation are proposed.     

Research trends and agenda on the Belt and Road (B&R) initiative with a focus on maritime transport

The ‘Silk Road Economic Belt and the 21st-Century Maritime Silk Road’ (collectively known as Belt and Road, B&R) has been initiated by the Chinese government in 2013. The B&R is increasingly becoming a focal point for socio-economic–political interests because of its likely impact on land and sea transport and maritime logistics. The aims of this study were threefold: first, to provide an overview on the B&R, focusing on its key structural elements, such as transport corridors, city clusters, dry ports, infrastructure, zoning, and area development; second, to identify the expected impacts of the B&R on trade and implications on structural changes in transportation systems, port networks, and international logistics. Finally, to discuss major research trends and setting up of research agenda which will contribute to enriching the existing literature and shaping the global trade operations and drive economic growth in the context of the B&R.     

A design for ship stabilization by activated antiroll tanks

An activated antiroll tank system design for ship roll reduction was investigated. Considering the dynamics of the ship motion, tank flow, and variable-pitch impeller, a control law is derived based on optimal control and estimation theory. Finally, a series of numerical computations for a 1174 tonne ship without an antiroll tank system, with a passive tank system, and with the proposed activated antiroll tank system is performed. The results show that the proposed activated tank system has superior antiroll properties for free rolling, regular, and irregular sea loads to the passive tank system. In addition, this design has a very low sensitivity to variations in ship and tank dynamics. It shows that the proposed system is reliable and valid for practical use.     

Internal tidal currents in the Gaoping (Kaoping) Submarine Canyon

Data from five separate field experiments during 2000–2006 were used to study the internal tidal flow patterns in the Gaoping (formerly spelled Kaoping) Submarine Canyon. The internal tides are large with maximum interface displacements of about 200 m and maximum velocities of over 100cm/s. They are characterized by a first-mode velocity and density structure with zero crossing at about 100 m depth. In the lower layer, the currents increase with increasing depth. The density interface and the along-channel velocity are approximately 90° out-of-phase, suggesting a predominant standing wave pattern. However, partial reflection is indicated as there is a consistent phase advance between sea level and density interface along the canyon axis.