• Journal of Korea Society of Digital Industry and Information Management
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• v.4 no.3
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• pp.97-101
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• 2008

In this paper, an assembly education training system is presented using AR (augmented reality). The effectiveness of the training using the proposed system is verified on a PC assembly training experiment. The experimental results confirmed the training using the proposed system is more effective than that using the conventional systems based on texts and images by reducing the assembly (task) time.

• Journal of the Society of Naval Architects of Korea
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• v.46 no.1
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• pp.78-86
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• 2009

A capacity calculation and process analysis is a very important part for the entire ship production planning. Ship's production plan is set up with a concept that the product is produced based on the capacity achievable by the processes while general manufacturing sets up the production plan based on product lead-time. Therefore, in case the calculation of capacity for each process of shipbuilding yard is different from actual conditions, a series of production plan - ship table composition, dual schedule plan and execution schedule plan, etc - may accumulate errors, lose reliability of planning information and cause heavy cost deficit in this course. In particular, in case of new shipbuilding yard, stocks between processes are built up and half blocks are not supplied in timely manner, and that is sometimes due to the clumsiness of the operator but it is more often because of the capacity to execute each process is not logically calculated. Therefore, this paper presents the process to calculate the assembly leadtime and assembly process capacity for shipbuilding yard assembly factory. This paper calculated the block type for calculation of assembly lead time based on block DAP(detailed assembly procedure), and introduced cases that calculate production capacities by assembly surface plate by considering the surface plate occupied area of the blocks that change depending on assembly field area and assembly processes through assembly simulation.

• Journal of the Korean Operations Research and Management Science Society
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• v.33 no.3
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• pp.1-16
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• 2008

This paper considers a scheduling problem to minimize the total tardiness in the two-stage assembly-type flowshop. The system is composed of multiple fabrication machines in the first stage and a final-assembly machine in the second stage. Each job consists of multiple tasks, each task is performed on the fabrication machine specified in advance. After all the tasks of a job are finished, the assembly task can be started on the final-assembly machine. The completion time of a job is the time that the assembly task for the job is completed. The objective of this paper is to find the optimal schedule minimizing the total tardiness of a group of jobs. In the problem analysis, we first derive three solution properties to determine the sequence between two consecutive jobs. Moreover, two lower objective bounds are derived and tested along with the derived properties within a branch-and-bound scheme. Two efficient heuristic algorithms are also developed. The overall performances of the proposed properties, branch-and-bound and heuristic algorithms are evaluated through numerical experiments.

• IE interfaces
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• v.17 no.2
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• pp.208-217
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• 2004

This paper deals with a process planning problem in the flexible assembly system (FAS). The problem is to assign assembly tasks to stations with limited working space and to determine assembly routing with the objective of minimizing transfer time of the products among stations, while satisfying precedence relations among the tasks and upper-bound workload constraints for each station. In the process planning of FAS, the optimality of assembly routing depends on tasks loading. The integration of tasks loading and assembly routing is therefore important for an efficient utilization of FAS. To solve the integrated problem at the same time, in this paper we propose a new method using an artificial intelligent search technique, named 2-leveled symbiotic evolutionary algorithm. Through computational experiments, the performance of the proposed algorithm is compared with those of a traditional evolutionary algorithm and a symbiotic evolutionary algorithm. The experimental results show that the proposed algorithm outperforms the algorithms compared.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.12 no.3
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• pp.48-53
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• 2013

An automotive air conditioning assembly consists of a condenser, a compressor and an evaporator. These major components are connected with rubber hoses and aluminum pipes. Once mounted on the automotive air conditioning assembly, it is exposed to a serious vibration environment for a long time. In some cases, there are vibration cracking on the assembly. In order to solve this vibration problem, several real vibration tests are performed on the assembly of which the lay-out was optimized, in spite of sample production cost and making time. In this study, a frequency response analysis, which is a kind of finite element method of the vibration, was performed to know the characteristic of the vibration transmission on the assembly lay-out. The analysis result indicated the damping performance, which is satisfied with the vibration standard of car maker, in rubber hoses and the whole assembly.

• Industrial Engineering and Management Systems
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• v.4 no.2
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• pp.117-122
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• 2005

An assembly system (AS), a valuable tool for mass production, is generally composed of a number of workstations and a transport system. While the workstations perform some preplanned operations, the transport system moves the assemblies by special designed pallets from one station to another. One common problem associated with automatic assembly systems is that some assembly operations may have relatively long cycle times. As a consequence, the productivity, as determined by the operations with the longest cycle time, can be reduced significantly. Therefore, special forms of parallel workstations were developed to improve the performance of an assembly system. In this paper, three most commonly used parallel stations: on-line, off-line and tunnel-gated stations in a free transfer assembly system are studied via discrete event simulation. Our findings revealed that the off-line parallel system has the best performance because the two independent parallel stations can lower the buffer requirement; reduce the sensitivity to variability of processing time and balance of a line. On-line parallel systems were found to have a relatively poor performance, because the operations of two parallel stations block each other, and higher buffer capacity is required to achieve similar capacity. The tunnel-gated system was more efficient than the on-line system since the first parallel station can operate independently. More importantly, we have quantified the productivity of the three different strategies mentioned. Engineers can choose the optimal strategies for installing parallel stations under their working environment.

• Nuclear Engineering and Technology
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• v.51 no.3
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• pp.922-929
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• 2019

This paper presents the drop performance test of the control rod assembly which is one of the main components strongly related to the safety of the prototype generation IV sodium-cooled fast reactor. To investigate the drop performance, a real-sized control rod assembly that was recently modified based on the drop analysis results was newly fabricated, and several free drop tests under different flow rate conditions were carried out. Then the results were compared with those obtained from the previous tests conducted on the conceptually designed control rod assembly to demonstrate the improvement in performance. Moreover, the drop performance tests under several types and magnitudes of seismic loadings were also conducted to investigate the effect of the seismic loading on the drop performance of the modified control rod assembly. The results showed that the effects of the type and magnitude of the seismic loading on the drop performance of the modified control rod assembly were not significant. Also, the drop time requirement was successfully satisfied, even under the seismic loading conditions.

• Journal of the Korean Society for Precision Engineering
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• v.25 no.8
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• pp.37-44
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• 2008

Nowadays, the increasing global competition forces manufacturer to reduce the cost and time for implementation of manufacturing system. The AR(augmented reality) technology as a new human-machine interface introduces a noteworthy perspective for a new manufacturing system design. Using AR technology, a physically existing production environment can be superimposed with virtual planning objects. Therefore, the planning tasks can be validated without modeling the surrounding environment of the production domain during short process planning time. In this paper, we introduce the construction of AR browser and determine the optimal environment parameters for field application of AR system through lots of tests. And, many methods such as multi-marker coordinate system, division of virtual objects and so on, are proposed in order to solve the problems suggested from initial field test. Based on these tests and results, the test-bed of C/Pad assembly system is configured and robot program for C/Pad assembly is generated based on AR system.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.19 no.40
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• pp.253-261
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• 1996

In optimizing the layout design of a multi-product assembly environment, tile analysis of the material flow is a vital ingredient. In flexible assembly systems, assembly time is usually very short thus the transfer time is relatively more important Therefore operations sequence must be so determined, that have no backtracking operations as possible as, It is important to form cells, so that they have no intercell movement in curring much processing delay, and to arrange machines as possible as densly. This study presents a independent cell formation method considering operation sequences and machine capacity in flexible assembly systems.

• IE interfaces
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• v.16 no.2
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• pp.240-247
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• 2003

Generally, the assembly system relied on conveyor lines is efficient for mass production. But it is not efficient when the product types are often varying and their lot sizes are small. Especially, it is much inefficient for the assembly lines for the electronic products whose types are varying very often. This paper suggests the design of U-shaped assembly lines to replace the existing conveyor systems. The assembly line for the mini-cassette production is dealt with as a case study. The proposed procedure was successfully applied for the design of U-shaped lines. The developed method resulted in the improvement of the productivity such as the decrease of the man power and the cycle time, and the increase of the line utility.