• Journal of Korean Association for Spatial Structures
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• v.13 no.2
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• pp.57-66
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• 2013

There are a number of construction methods to build spatial structures such as erection method, Element method, Block method, Sliding method, Lift-up method and Push-up method. These methods are uneconomical and low accuracy, and require long construction duration because of a need of a scaffold or a tower crane to build spatial roof frame. In this study, the construction method to erect a truss structure was proposed as an economical and easy installation method. The proposed method has end hinges of keel truss and winches with horizontal cable. This method makes safe and accurate production and reduces construction duration because trusses are built on the floor or supporter. The goal of this study is to verify the validity of construction method by building scale model using the proposed method.

• Journal of Korean Association for Spatial Structures
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• v.8 no.3
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• pp.45-51
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• 2008

A single layer-latticed dome is advantageous for large span structures because it is very stiff despite the light weight of the structure itself. However, this structure becomes easily unstable during erection due to its large size. The Block method is popular with the large span structures. A partial block of the dome is fabricated on the ground and lifted by crane to a designated location of structures. The lifting point selection is very important to create a stable erection and to avoid buckling of members during the erection. The purpose of this study is to analyze the structural behaviors and buckling characteristics according to the lifting point of single-layer latticed domes with triangle network in order to take materials about the safe and economic erection. The conclusions are obtained as follow. 1) The buckling strength of the block part varies with the location of lifting points when it is erected. In case, the height of the dome is lower, the effort of buckling strength of the structure is higher. 2) In buckling strength, the effect of the lifting rope length is smaller than it of the lifting points change.

• Special Issue of the Society of Naval Architects of Korea
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• 2005.06a
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• pp.165-170
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• 2005

The weight of a ship depends on the size of the ship. Normal lightweight of a ship is over 10,000 tons. So it is inevitable to divide a ship into about more than hundreds of lumps. Each of lumps is called as a block in shipbuilding. The sizes of blocks are decided by a yard's facilities. Among them lifting cranes are most decisive facilities. By block's size the productivity of a yard is decided very much. So it is very important to have a proper block division during shipbuilding. This paper refers to the recent trend of block division among yards. This paper would give an idea how to decide boundaries of blocks. Block division also decides both quality of a ship and work volume of it. These days the block erection method is changed dramatically due to use sea barge mounted crane for erection of a grand ring block. This paper explains the new trend of block division in shipbuilding.

• Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
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• 2002.05a
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• pp.47-50
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• 2002

선반건조 일정계획에 있어서 탑재 공정은 전체 생산일정 계획 중 선박 한 척에 대한 계획의 시발점이 되며, 병목현상 등을 유발하여 다른 일정에 가장 큰 영향을 주게 되는 공정이다. 최근 많은 조선소에서 하나의 Dock 내에서 두 착 이상의 배를 동시에 건조하는 tandem 방식을 택하고 있어 dock 내의 한정된 Crane 의 개수와 Crane의 Capacity, 공수 등의 자원, 그리고 작업환경에서 일어날 수 있는 여러 가지 변수들을 제대로 고려하지 못 했을 시에는 일정의 차질과 Dock의 회전율을 떨어트리게 한다. 본 논문에서는 가상공간에 하나의 Dock 를 만들어서 일정계획에서 작성한 Network를 사용하여 실제 작업하게 해서 그 Network가 현장에서의 최적한가를 점검하게 하고 현장에서 수정하는 작업을 줄이게 하는 것의 방법으로 simulation을 개발하였다.

• Proceedings of the Korean Institute Of Construction Engineering and Management
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• autumn
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• pp.232-239
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• 2001

Young Jong Grand Bridge is approach traffic road of New Inchon International Airport which covers hub airport function in northeast asia. The total span length of this bridge is $4,420{\cal}m$ and this main bridge type is, the first in the world, Double Deck Self Anchored Suspension Bridge, designed as double deck systems to be arranged by road and railroad. Approach bridges to be connected with main span also are composed double deck steel truss and steel box girder to consider a continuity with this span. Our company erected $1,375{\cal}m$(about 60,000tons) of double deck steel truss bridge type which is composed by 6 traffic lane on upper deck and 4 traffic lane and Double track railroad on lower deck. The original installation method of this bridge was planed to install about 75 meters bridge blocks to use floating crane, after temporary bent was constructed between permanent piers. But this method which had to construct many temporary bents in the sea had the matter that construction periods can become lengthen and construction cost can be risen. To overcome the uncertainty to ensure high qualify of bridge and economic project execution, our company developed new bridge erection method to assure both quality control and economic construction work. The new erection method which was developed by us was one that could transport and install long bridge block, $120{\cal}m$ unit at a time and that temporary bent was not required. We hope that this paper is used as technical data which will erect bridge in the western sea and others marine region.

• Journal of Korean Association for Spatial Structures
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• v.14 no.2
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• pp.69-78
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• 2014

The purpose of this study is to increase applicability of high strength steel, HSA800 to the structure. Selected study of structure is to consider high strength steel, and following parts, 1) Tensile member with no consider of buckling, 2) Truss existing both tension and compression members with small slenderness ratio. This studied structure is included tension column hang on to the upper bridge truss. The structure element quantity with apply HSA800 instead of SM570 is reduced about 38.9% of tension column and 29.7% of bridge truss. In addition, the number of element's division is reduced about two sections due to reduction of self weight that the crane is able to lift up. This improves to reduce erection sequence and construction period which can save about a month. All connections are reviewed as welding and bolt. Also, the cost of welding is reduced about 41.3% due to apply HSA800. In conclusion, applying HSA800 to the hanging structure aggressively can secure economic and constructability.

• Journal of the Society of Naval Architects of Korea
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• v.49 no.4
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• pp.304-311
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• 2012

One of the main features of Drillship or FPSO is a moonpool structure. The moonpool structures have various accuracy tolerances according to their functions and targets. This study is mainly interested in roundness of a circular moonpool structure in FPSO. Because this structure needs abrasion-resistance at which bearing of machine touches on inner wall of moonpool, we should do over-lay welding widely and deeply by using Inconel weld material. But a general over-lay can cause a severe distortion at ship block structure. If we can analyze the roundness by thermal distortion under Inconel over-lay, we can establish a special erection policy by the results. In this study, we designed stress-strain curve for strain-boundary condition analysis by an elasto-plastic material property. The results made us to decide an appropriate ship-block size and policy of crane manipulation will follow for its capacity. If a structure that needs over-lay is not large, solid elements also are not a bad choice for FEM modeling. Therefore we also developed a standard of using strain-boundary method that shell elements are used as over-lay on solid element modeling.

• Journal of Welding and Joining
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• v.30 no.6
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• pp.120-125
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• 2012

Because ships and offshore structures have very large dimensions and complicated shapes, it is difficult to determine the deformation or internal stress in the structure by simple lab tests. Thus, a rigorous analysis by using the computer simulation technology is essential for obtaining their distortions by considering the entire production process characteristics. The rapid development of computer technology made it possible to analyze the heat transfer phenomena, deformation and phase transformation in the welded joint. For large shell structures, shell elements modeling contributed primarily to this development. But if a welding is done by multi-pass, shell elements whose thickness are unchangeable can hard to describe the local situation. Recently, it was researched how to introduce the imaginary temperature for V grooved multi-layer butt welding in strain-boundary method (a kind of shrinkage methodologies). In the present study, we formulated the imaginary temperature for the double bevel and double V groove by considering the thickness change of each pass through the bead and the thickness directions simultaneously and also demonstrated the feasibility of the formula by applying it to the thermal distortion analysis of the erection process of crane pedestal.

• IE interfaces
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• v.15 no.3
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• pp.230-240
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• 2002

Information technologies centered on the internet in the area of shipbuilding and marine engineering further incur the needs to increase the flexibility of the organization, the dispersion of work process, and the use of out sourcing, as well as the globalization of related market. In near future, electronic commerce and concurrent engineering based on CALS/EC and the Internet will be an integral part of the environment and upon these changes, ship design and construction will become a computer supported cooperative work of many dispersed and specialized groups. As the means of active response to these environmental changes, many new concepts such as digital shipbuilding, virtual shipyard, and simulation based design are appearing. In this paper, the concept and current status of digital manufacturing in general manufacturing industry will be reviewed. Then, related technologies, area of application and methods of digital manufacturing in shipbuilding and marine industries are presented. In addition, virtual assembly simulation system for shipbuilding(VASSS), a tool for crane operability and block erection simulation in virtual dock based on 3D product model, will be introduced.

• IE interfaces
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• v.24 no.1
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• pp.78-86
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• 2011

To mitigate space restriction and to raise productivity, some shipbuilding companies use floating-docks on the sea instead of dry-docks on the land. In that case, a floating-crane that can lift very heavy objects (up to 3,600 tons) is used to handle the blocks which are the basic units in shipbuilding processes, and so, very large blocks (these are called the mega-blocks) can be used to build a ship. But, because these mega-blocks can be made only in the area near the floating-dock and beside the sea, the space is very important resource for the process. Therefore, our problem is to make an efficient spatial schedule for the mega-block assembly yard. First of all, we formulate this situation into a mathematical model and find optimal solution for a small problem using a commercial optimization software. But, the software could not give optimal solutions for practical sized problems in a reasonable time, and so we propose a GA-based heuristic algorithm. Through a numerical experiment, finally, we show that the spatial scheduling algorithm can provide a very good performance.