• Proceedings of the Korea Society for Simulation Conference
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• 2003.11a
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• pp.185-192
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• 2003

Digital Manufacturing-based production could be very effective in shipbuilding in order to save costs and time, to increase safety for workers, and to prevent bottleneck processes in advance. Digital shipbuilding system, a simulation-based production tool, is being developed to achieve such aspects in Korea. To simulate material flow in a subassembly line at a shipyard, the product, process and resources was modeled for the subassembly process which consisted of several sub-processes such as tack welding, piece alignment, tack welding, and robot welding processes. The analysis and modeling were carried out by using the UML(Unified Modeling Language), an object-oriented modeling method as well as IDEF(Integration DEFinition), a functional modeling tool. Initially, the characteristics of the shop resources were analyzed using the shipyard data, and the layout of the subassembly line was designed with the resources. The production process modeling of the subassembly lines was performed using the discrete event simulation method. Using the constructed resource and process model, the productivity and efficiency of the line were investigated. The number of workers and the variations In the resource performance such as that of a new welding robot were examined to simulate the changes in productivity. The bottleneck process floated according to the performance of the new resources. The proposed model was viewed three-dimensionally in a digital environment so that interferences among objects and space allocations for the resources could be easily investigated

• Proceedings of the KSME Conference
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• 2004.04a
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• pp.1070-1075
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• 2004

Many mid-sized companies in Korean automotive industry have attempted to solve the lack of human power, to control the quality of components, to improve the production rate, and to innovate the manufacturing line. The goals of this study are to analyze the production rate of an automotive component manufacturing line using simulation software, to construct a Flexible Automation Subassembly (FAS) system and to suggest an optimized layout design using FAS line. In this research, the simulation model for manufacturing line was developed and used the realistic data (production planning, component type, working order, process time, queue time, line rules, etc) of a medium sized company in Korean automotive industry. To complete this research, a simulation software 'ARENA' was used.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.29 no.1 s.232
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• pp.38-44
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• 2005

Many mid-sized companies in Korean automotive industry have attempted to solve the lack of human power, to control the quality of components, to improve the production rate, and to innovate the manufacturing line. The goals of this study are to analyze the production rate of an automotive component manufacturing line using simulation software, to construct a Flexible Automation Subassembly (FAS) system and to suggest an optimized layout design using FAS line. In this research, the simulation model for manufacturing line was developed and used the realistic data of a medium sized company in Korean automotive industry. To complete this research, a simulation software 'ARENA' was used. This research analyzed the work distribution strategy and cycle time element for production flow and proposed an optimized layout to resolve line balancing problem which would bring the improved production rate.

• Journal of the Korean Operations Research and Management Science Society
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• v.17 no.1
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• pp.55-65
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• 1992

There are takes performed on only one side (right side or left side) of the assembly line, and task groups in which the tasks are more related to one another like a subassembly. In the Assembly Line Balancing (ALB) of the large-sized product such as bus and truck, the side on which tasks are performed and the related task groups should be considered to improve work methods and to appropriately lay out parts and facilities in the line. In this paper, presented are the 0-1 programming formulations for the ALB with the constraints of assigning the same side tasks to the station. The objective of minimizing the number of stations is combined with the objective that the total number of the related task groups handled by all the stations is minimized. Also, proposed are the methods of reducing the number of variables and constraints, and of determining the station to which subassembly tasks are assigned.

• Journal of the Korea Society for Simulation
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• v.19 no.1
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• pp.73-82
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• 2010

Productivity improvement is considered as one of hot potato topics in international shipyards by the increasing amount of orders. In order to improve productivity of lines, shipbuilders have been researching and developing new work method, process automation, advanced planning and scheduling and so on. An optimization approach was accomplished on short-term scheduling of subassembly lines in this research. The problem of subassembly line scheduling turned out to be a non-deterministic polynomial time problem with regard to SKID pattern’s sequence and worker assignment to each station. The problem was applied by simulated annealing algorithm, one of meta-heuristic methods. The algorithm was aimed to avoid local minimum value by changing results with probability function. The optimization result was compared with discrete-event simulation's to propose what pros and cons were. This paper will help planners work on scheduling and decision-making to complete their task by evaluation.

• Proceedings of the KWS Conference
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• 2004.05a
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• pp.18-20
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• 2004

This study is to find the optimal work plan of robot welding in the subassembly process of shipbuilding and to verify the found solution through 3-D simulation. The optimal work plan was established by evenly distributing the work amount to each stage and finding the shortest work sequence. The shortest work sequence was found by using the genetic algorithm. The result was compared with the practically adopted case and verified through the 3-D simulation.

• Korean Journal of Computational Design and Engineering
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• v.10 no.3
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• pp.210-216
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• 2005

Digital manufacturing could be very effective in shipbuilding in order to estimate the process time, to improve the operation efficiency, and to prevent bottleneck processes in advance. The subassembly process having done research consists of piece arrangement, tack welding, robot welding, manual welding and so on. The robot welding of them was the focus of the simulation. The analysis and modeling were carried out by using UML (Unified Modeling Language) as well as $IDEF\phi$ (Integration DEFinition). The characteristics of the process resources were analyzed using the shipyard data, and the layout of the subassembly line was designed with the resources. Using the constructed resource and process model, the productivity and efficiency of changed robot welding stage were investigated. It was simulated how much the variations in the resource performance have influence on improvement of productivity. One of the important outputs in this simulation was the cycle time during a certain period's work. The cycle time prediction was also undertaken for the different torch and the different piece arrangement. The proposed model was established three-dimensionally in a digital environment so that interferences among objects and space allocations for the resources could be easily investigated.

• 제어로봇시스템학회:학술대회논문집
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• 1997.10a
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• pp.361-364
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• 1997

There has been requested to automate the welding process in shipyard due to its dependence on skilled operators and the inferior working environments. According to these demands, multiple robot welding system for sub-assembly welding line has been developed, realized and installed at Keoje Shipyard. In order to realize automatic welding system, robots have to be equipped with the sensing system to recognize the position of the welding panels. In this research, a camera vision system is developed to detect the position of base panels for subassembly line in shipbuilding. Two camera vision systems are used in two different stages (Mounting and Welding) to automate the recognition and positioning of welding lines. For automatic recognition of panel position, various image processing algorithms are proposed in this paper.

• ETRI Journal
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• v.35 no.1
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• pp.1-6
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• 2013

In this paper, we present an implemented serial 40-Gb/s receiver optical subassembly (ROSA) module by employing a proposed TO-CAN package and flexible printed circuit board (FPCB). The TO-CAN package employs an L-shaped metal support to provide a straight line signal path between the TO-CAN package and the FPCB. In addition, the FPCB incorporates a signal line with an open stub to alleviate signal distortion owing to an impedance mismatch generated from the soldering pad attached to the main circuit board. The receiver sensitivity of the ROSA module measures below -9 dBm for 40 Gb/s at an extinction ratio of 7 dB and a bit error rate of $10^{-12}$.

• Journal of Korean Institute of Industrial Engineers
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• v.25 no.1
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• pp.21-34
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• 1999

We consider a scheduling problem arising in a shipyard subassembly welding process. There are four welding robots of gantry type, which perform the welding process for the subassemblies. Because the robots perform the welding operations at the same time, there is a possibility of collision between adjacent robots depending on the welding schedule. In this paper, we propose a heuristic method to find a welding schedule which does minimize the welding completion time while avoiding collision among the robots. The method consists of two phases: assignment and scheduling. In the assignment phase, we assign each welding line to a proper robot. In the scheduling phase, we determine the welding schedules for the robots so that collision is avoided. Computational experiences with the data which reflect the real situation are reported.