• Proceedings of the Korean Operations and Management Science Society Conference
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• 2002.05a
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• pp.272-279
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• 2002

A common task in assembly modeling is the determination of the position and orientation of a set of components by solving the spatial relationships between them. Assembly models could be constructed at various levels of abstraction. They could be classified into component or geometry-level assembly models. The geometry-level assembly design approach using mating constraints such as against and fits is widely used in the commercial modelers, but it may be very tedious in some cases fur designer. In this paper, we propose a new method to construct an assembly model at the component-level by extracting joint mating features from the kinematics constraints specified between components. The assembly model constructed using the proposed method includes hierarchical and relational assembly models, component/sub-assembly positions and degrees of freedom information. The proposed method is more intuitive and natural way of assembly design and it guarantees the topological robustness of assembly modification such as component replacement and modification.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1995.10a
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• pp.938-941
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• 1995

This paper is concerned with the determination of assembly unit for hull block assembly processes for shipbuilding. In this study,genetic algorithm is adopted for assembly level allocation and assemaly unit is determined by rule-based reasoning. The criteria to detemine assembly unit is to minimize welding operation time for the block assembly.

• Transactions of the Korean Society of Mechanical Engineers
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• v.19 no.7
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• pp.1604-1618
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• 1995

In the process of mechanical assembly design, assembly modeling systems have been used mainly for the design verification before manufacturing by enabling to check the interference and/ or the dynamic and kinematic performance. However, the conventional assembly modeling systems have a shortcoming that they can not be used in the initial design stage but can be used only after the design is fully completed. In other words conventional assembly modeling systems provide bottom-up modeling which means that the detailed modeling of components must precede the definition of relationships between them. To resolve this problem, an assembly modeling system is proposed to provide a top-down modeling environment in which components and assembly can be modeled simultaneously. To this end, an assembly data structure suitable for top-down assembly modeling has been established. Feature positioning Module(FPM) using geometric constraints has been also developed. The Sekective Solving Method proposed for FPM is based on the priority between the constraint equations and enables the designer's intent expressed by geometric constraints to be maintained throughout the whole modeling process. Finally, the feature based modeling technique using two-level features has been developed. Two-level features include an abstract model and a detailed model in a merged form in non-manifold data frame.

• Journal of the Korean Operations Research and Management Science Society
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• v.22 no.1
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• pp.25-49
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• 1997

Printed circuit board (PCB) assembly line configuration is characterized by very long set-up times and high work in process (WIP) inventory level. The scheduling method can significantly reduce the set-up times and WIP inventory level. Greedy sequence dependent scheduling (GSDS) method is proposed based on the current methods. The proposed method is compared with the current method in terms of three performance measures: line throughput, average WIP inventory level, and implementation complexity.

• 대한공업교육학회지
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• v.45 no.2
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• pp.1-20
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• 2020

The purpose of this study is to develop an assembly-type liquid level control experimental equipment and a hands-on activity task that can be applied to the class so that students studying the chemical industry can easily understand the liquid level control. For this purpose, the content elements related to liquid level control in the chemical industry practice course of the 2015 revised curriculum was analyzed, a hands-on activity task with an assembly-type liquid level control experimental equipment was and developed. And then, expert verification was also performed and the hands-on activity task was applied to 19 students of S meister high school. The results obtained through this are as follows. First, the existing completion-type liquid level control experimental equipment was explored, and based on this, a new assembly-type liquid level control experimental equipment that can be assembled by students and used for practices was designed and manufactured. Second. by analyzing the contents of the NCS-based 'Chemical Process Maintenance Operation' practical course of the 2015 revised curriculum, learning contents related to level control were extracted. Among the contents related to the level control, the practice with understanding the process flow chart, manufacturing the level control experimental equipment, measuring the flow rate, and checking the level control phenomenon were conducted with the assembly-type liquid level control experimental equipment to systematically learn the level control.

• Journal of the Korean Society for Precision Engineering
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• v.13 no.4
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• pp.34-42
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• 1996

Robot programming has been discussed in detail during the recent years. Numerous studies in particular presented relevance, solution concepts and implementation of off-line programming. In this paper a new user-friendly robot programming method is introduced, which permits the implicit description and programming of assembly process. On the functional level of programming, the assembly processes are described in terms of their operational functions. On the language level, the individual functions are then translated into commands for the robots.

• Journal of the Korean Operations Research and Management Science Society
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• v.35 no.3
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• pp.25-43
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• 2010

We consider a multi-objective balancing and sequencing problem in mixed model assembly lines, which is important for an efficient use of the assembly lines. In this paper, we present a neighborhood symbiotic evolutionary algorithm to simultaneously solve the two problems of balancing and model sequencing under multiple objectives. We aim to find a set of well-distributed solutions close to the true Pareto optimal solutions for decision makers. The proposed algorithm has a two-leveled structure. At Level 1, two populations are operated : One consists of individuals each of which represents a partial solution to the balancing problem and the other consists of individuals for the sequencing problem. Level 2, which is an upper level, works one population whose individuals represent the combined entire solutions to the two problems. The process of Level 1 imitates a neighborhood symbiotic evolution and that of Level 2 simulates an endosymbiotic evolution together with an elitist strategy to promote the capability of solution search. The performance of the proposed algorithm is compared with those of the existing algorithms in convergence, diversity and computation time of nondominated solutions. The experimental results show that the proposed algorithm is superior to the compared algorithms in all the three performance measures.

• Journal of Korean Institute of Industrial Engineers
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• v.17 no.1
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• pp.83-94
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• 1991

This study is concerned with the scheduling problem for mixed-model assembly lines in Just-In-Time(JIT) production systems. The most important goal of the scheduling for the mixed-model assembly line in JIT production systems is to keep a constant rate of usage for every part used by the systems. In this study, we develop two heuristic algorithms able to keep a constant rate of usage for every part used by the systems in the single-level and the multi-level. In the single-level, the new algorithm generates sequence schedule by backward tracking and prevents the destruction of sequence schedule which is the weakest point of Miltenburg's algorithms. The new algorithm gives better results in total variations than the Miltenburg's algorithms. In the multi-level, the new algorithm extends the concept of the single-level algorithm and shows more efficient results in total variations than Miltenburg and Sinnamon's algorithms.

• Korean Journal of Legislative Studies
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• v.15 no.1
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• pp.119-143
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• 2009

Public disapproval of National Assembly is resulted not only from the structural peculiarity of its decision-making process, but from the gap between public expectation of the National Assembly and its performance. While Korean electorate, being interested in politics with relatively high level of political efficacy, hold higher expectation from politics, the National Assembly fails to satisfy public expectation. In particular, irresponsible behaviors of representatives and the crippled operation of the National assembly are responsible for the low level of public trust to it. Institutional reform and individual efforts of representatives are necessary to promote public trust toward the National Assembly.

• Nuclear Engineering and Technology
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• v.30 no.3
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• pp.212-221
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• 1998

In the present study, a method for the dynamic analysis of a reactor core is developed. Peak responses for the motions induced from earthquake are obtained for a core model. The dynamic responses such as fuel assembly shear force, bending moment, axial force and displacement, and spacer grid impact loads are investigated. Prediction of fuel assembly stress during an earthquake requires development of a fuel assembly stress analysis model capable of interfacing with the models and results discussed in the dynamic analysis of a reactor core. This analysis uses beam characteristics which describe the overall fuel assembly response. The stress analysis method and its application for the case of an increased seismic level are also presented.