• Journal of Welding and Joining
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• 제33권3호
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• pp.62-67
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• 2015

A very large shell-structure built in shipyards like ship hulls or offshore structures are joined by welding through full process. As the welding contains a high thermal cycle at a local area, the welded structures should be distorted unavoidably. Because a distorted ship block should be revised to the designed value before the next stage, the ability to predict and to control the weld distortion is an accuracy level of the yard itself. Despite the ship block size, several present thermal distortion methodologies can deal those sizes, but it is a different story to deal full ship size model. Even a fully constructed ship hull not remaining any welding can have an accuracy issue like outfitting installation problems. Any present thermal distortion methodology cannot accept this size for its recommended element size and the number. The ordinary welding breadth at erection stage is about 20~40 mm. It can hardly be a good choice to make finite element model of these sizes considering human effort and computational environment. The finite element model for structure analysis of a ship hull is prepared at front-end engineering design stage which is the first process of the project. The element size of the model is as fine as the longitudinal space, and it is not proper to obtain a weld distortion at the erection stage. In this study, a methodology is suggested that a weldment can be shrunk at original place instead of using structural finite element model. We cut the original shell elements at erection weld-line and put truss elements between the edges of cut elements for weld shrinkage. Additional truss elements are used to facsimile transverse weld shrinkage which cannot be from the weld-line truss element shrink. They attach to weld-line truss element like twigs from barks. The capacity of developed elements is verified through an accuracy check of erection process of a container vessel at the apt. hull. It can be a useful tool for verifying a centering accuracy after renew and for block-separating planning considering accuracy.

• 한국CDE학회논문집
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• 제7권3호
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• pp.157-169
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• 2002

In the initial stages of ship design, designers represent geometry, arrangement, and dimension of hull structures with 2D geometric primitives such as points, lines, arcs, and drawing symbols. However, these design information(‘2D geometric primitives’) defined in the drawing sheet require more intelligent translation processes by the designers in the next design stages. Thus, the loss of design semantics could be occurred and following design processes could be delayed. In the initial design stages, it is not easy to adopt commercial 3D CAD systems, which have been developed f3r being used in detail and production design stages, because the 3D CAD systems require detailed input for geometry definition. In this study, a semantic product model data structure was proposed, and an initial structural CAD system was developed based on the proposed data structure. Contents(‘product model data and design knowledges’) of the proposed data structure are filled with minimal input of the designers, and then 3D solid model and production material information can be automatically generated as occasion demands. Finally, the applicability of the proposed semantic product model data structure and the developed initial structural CAD system was verified through application to deadweight 300,000ton VLCC(Very Large Crude oil Carrier) product modeling procedure.

• 대한조선학회논문집
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• 제29권2호
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• pp.30-37
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• 1992

선체는 매우 복잡한 구조물이므로 설계 및 생산의 효율적인 수행을 위하여 선체구조의 모델링에 의한 작업이 필수적이다. 선체모델 구축에 있어서 구조면의 모델링은 초기선형정의에서부터, 선각정보처리, 구획배치, 의장설계, 배관설계, 구조해석 등 선체관련분야와 직접 연관된다. 본 연구에서는 구조면의 효과적인 모델링을 위하여 구조면들간의 위상학적인 자료구조를 구성하므로써 선체구조의 기하학적 정보를 설계의 단계에 따라 발전시켜 나가고 효율적으로 변경시킬 수 있도록 하였다. 본 연구에서 수행된 구조면의 모델링은 선체설계에서부터 생산에 이르기까지 일관된 정보처리를 위한 통합선체모델(Unified Hull Model)구축의 기초가 될 것이다. 구축된 모델의 가시화를 위하여 컴퓨터그래픽스를 이용하여 선체모델을 실물감 있게 표현하였다.

• 수산해양기술연구
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• 제47권4호
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• pp.435-442
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• 2011

In an attempt to respond to the increase in international oil prices and reduce operating expenses, ship remodeling was carried out on a 740ton class tuna purse seiner. To strengthen the competitiveness of the fisheries industry by improving vessel performance, a bulbous bow was newly equipped. The slipway and rudder area were also lengthened and enlarged with the propeller and main engine remained unchanged. To reduce the hull resistance, a circle type bulbous bow was attached on the hull behind bow thruster and thus the cost for exchanging electrical equipment for bow thruster was reduced. The new rudder area was expanded 15% more than the old one within the extent that the existing mechanical control part and rudder stock were not changed. To prevent fishing net damage and stabilize wake field, slipway was lengthened to the optimal position. All of the new design of remodeling parts went through the model tests in towing tank and CWC. Besides resistance test, all of necessary model test results were delivered for hydrodynamic character for the modified ship. The maneuvering simulation to verify that the remodeled ship satisfies the IMO rules was performed in both zigzag and turning tests. The estimated resistance with new bulbous bow and lengthened stern was reduced by 4.8% in the 2-dimensional analysis and 17.4% in the 3-dimensional analysis in comparison of conventional ship. The average reduction of resistance was estimated about 10%. Maneuvering character of modified hull form was found to satisfy all regulations under IMO. The remodeling of tuna purse seiner can not only improve fishing performance but also contribute to reduction of operating cost by saving energy for the fisheries industry.

• 대한조선학회논문집
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• 제50권5호
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• pp.334-342
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• 2013

In this paper, we analyze the procedure of the design manager for the enhancement of the hull production design process by use of the simulation method. Normally, design manager assigns design jobs according to various methods and estimates the corresponding results. When the construction drawing which is the output of the detail design where a design is dealt by zones, the design manager identifies blocks and analyzes their work difficulties, and assigns jobs to design engineers who are different in capabilities. These processes including the design engineer who can be modeled with man-hours evaluation model are represented in detail as a simulation model. As the high-level modeling for the discrete-event system, we use Event Graph model. And we implemented the simulation using Simkit which is open simulation engine for the discrete-event system. We made the simulation scenario to be written by a user in the scenario generator which is separated from the simulation model, and made the simulation result to be visualized in the form of Gantt chart in a Web. In the scenario of the irregular issuance for various construction drawings which contain different numbers of blocks, we performed the Monte-Carlo simulation according to various assignment methods to find the assignment result that satisfies the mid-term schedule.

• 대한조선학회논문집
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• 제53권4호
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• pp.275-281
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• 2016

One of the most important things for quality to meet ship-production schedule is an accuracy control. A ship is assembled by welding through whole production process, so it is important that loss by correction will not happen as much as possible by using some engineering skills like reverse design, reverse setting and margin for thermal shrinkage. These efforts are a quite effective in fabrication stages, but not in erection stages. If a ship block which consists of common steel is exposed to directional solar radiation, its dimensional accuracy will change high as time by its thermal expansion coefficient. Therefore, the measuring work would be often done at dawn or evening even with having a very accurate device. In this study, an FE analysis method is developed to solve this problem. It can change measured data affected by solar thermal distortion to ones not, even though ship-block is measured at an arbitrary time. It will use the time when measuring, the direction of block and the weather record by satellites. It is confirmed by a comparison between measured data of a ship-block and the result by suggested analysis method. Furthermore, a pre-processing system is also developed for fast application of the suggested analysis method.

• International Journal of Naval Architecture and Ocean Engineering
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• 제12권1호
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• pp.784-798
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• 2020

This paper presents the results of research on transverse shrinkage of welded butt joints conducted according to the principles of experimental design and under production conditions for two main welding techniques used in shipbuilding (FCAW and SAW). Analysis took into account the technological and structural parameters influencing the assembly suitability of a large steel structure. The presented method of evaluation makes it possible to apply approximation formulae to predict transverse shrinkage in real sections of a ship hull. The determined predictive formulae were verified to actual transverse shrinkage measurements during prefabrication of hull sections at a shipyard as well as the equations referring to the analyzed form of deformation available in the literature.

• 대한조선학회논문집
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• 제46권1호
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• pp.87-95
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• 2009

The applicability of optimization techniques for hull surface fitting has been important in the ship design process. In this research, the Genetic Algorithm has been used as a searching technique for solving surface fitting problem and minimizing errors between B-spline surface and the ship's offset data. The encoded design variables are the location of the vertex points and parametric values. The sufficient accuracy in surface fitting implies not only various techniques for computer-aided design, but also the future production design.

• 융합신호처리학회논문지
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• 제21권1호
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• pp.38-48
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• 2020

기존에 건조되어 있거나, 신규로 건조되고 있는 선저를 검사하기 위해선 전문 잠수부가 직접 수중 하부에서 육안으로 검사를 한다. 하지만 직접 사람이 하는 일이기 때문에 인명사고, 충돌사고 등 많은 위험이 뒤따른다. 이를 해결하기 위해 Visual Inspection을 위한 선박 검사용 수중 드론 개발이 필요하다. 수중 드론에 적용되는 기술과 각 부품의 용도와 제작 과정, 펌웨어 개발과 같은 제작 방법에 관해 기술하였으며 수중에서 드론 자체의 주행 능력과 크롤러를 이용한 주행 능력을 측정하여 차이를 비교해보고 위치 추적 장치 테스트를 통해 실제 위치와의 오차를 확인하였다. 본 연구를 통해 제작된 수중 드론을 작업 현장에서 사용하였을 때 인명사고를 예방하고 경제적 효과와 안정성을 얻을 것으로 기대된다.

• 대한조선학회논문집
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• 제46권1호
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• pp.57-68
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• 2009

In automotive industries, reusability of product information is increasing through database construction of previous product data. The product data is stored by data quality management in product information systems. For naval ships, have the functional similarity by the ships of the same classification and class, that are built by series. Information of hull structures as well as embarked equipments are similar. So it would be effective to use database systems that are considered product information quality of previous ships in design and production processes. In this paper we discuss product information quality in database construction of naval ship product models. For this, we propose a basic concept and reference model for data quality verification. Based on this concept, A verification guideline is defined and it is applied for the case study of the digital naval ship which was built to the naval ship product model.