• Journal of Korean Society of Industrial and Systems Engineering
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• v.29 no.1
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• pp.63-71
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• 2006

In this paper, we consider a planning problem arising from printed circuit board manufacturing industries. Given a set of several types of PCBs, component feeders and surface mounting machines in series in a PCB assembly line, the problem is to define the feeder allocation and job sequence with the objective of minimizing the total operation time of the line. We formulate the problem as a mathematical model. And, the problem is proven to be NP-hard, so a genetic algorithm is developed. Finally, we give test results to evaluate the performance of the genetic algorithm.

• Proceedings of the Korean Information Science Society Conference
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• 2001.04a
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• pp.751-753
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• 2001

지금까지 인간이나 다른 생물체의 전체 유전체 염기서열을 밝혀내는 작업은 크게 세가지 방법으로 진행되었다. Clone-by-clone approach, sequence tagged connector approach, random shotgun approach[1]가 그것인데 마지막의 random shotgun approach는 fragment assembly problem을 비롯한 여러 가지 전산학적인 문제들을 수반한다. 미생물체의 전체 염기서열을 random shotgun approach를 이용하여 밝혀낼 때 몇 가지 전산학적인 문제가 테크닉이 필요하며 그 중에서도 서열간의 forward, reverse의 mating 정보를 이용하는 것이 중요하다. 본 논문은 이러한 mating 작업을 한 눈에 볼 수 있게 하는 소프트웨어 페키지 “Mater”에 대해 소개하고자 하며 그 의미에 대해 논하고자 한다.

• Genomics & Informatics
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• v.10 no.1
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• pp.1-8
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• 2012

Recently, the technologies of DNA sequence variation and gene expression profiling have been used widely as approaches in the expertise of genome biology and genetics. The application to genome study has been particularly developed with the introduction of the nextgeneration DNA sequencer (NGS) Roche/454 and Illumina/ Solexa systems, along with bioinformation analysis technologies of whole-genome $de$ $novo$ assembly, expression profiling, DNA variation discovery, and genotyping. Both massive whole-genome shotgun paired-end sequencing and mate paired-end sequencing data are important steps for constructing $de$ $novo$ assembly of novel genome sequencing data. It is necessary to have DNA sequence information from a multiplatform NGS with at least $2{\times}$ and $30{\times}$ depth sequence of genome coverage using Roche/454 and Illumina/Solexa, respectively, for effective an way of de novo assembly. Massive shortlength reading data from the Illumina/Solexa system is enough to discover DNA variation, resulting in reducing the cost of DNA sequencing. Whole-genome expression profile data are useful to approach genome system biology with quantification of expressed RNAs from a wholegenome transcriptome, depending on the tissue samples. The hybrid mRNA sequences from Rohce/454 and Illumina/Solexa are more powerful to find novel genes through $de$ $novo$ assembly in any whole-genome sequenced species. The $20{\times}$ and $50{\times}$ coverage of the estimated transcriptome sequences using Roche/454 and Illumina/Solexa, respectively, is effective to create novel expressed reference sequences. However, only an average $30{\times}$ coverage of a transcriptome with short read sequences of Illumina/Solexa is enough to check expression quantification, compared to the reference expressed sequence tag sequence.

• Journal of the Korean Operations Research and Management Science Society
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• v.22 no.4
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• pp.133-149
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• 1997

The major two steps required to design a cellular layout are cell formation and cell layout. Because of the differences between manufacturing and assembly operations, the logic of cell formation and cell layout between an FMS and an FAS is not the same. Since the time for the assembly operations is usualaly relatively short, the transfer time is thus very crucial for the performance of assembly systems. Transfore in a cellular FAS it is more important to eliminate backtracking operations in assembly planning, not to allow intercellular movements in cell formation, and to arrange machines according to assembly sequence in cell layout. This study presents a method for the integrated layout design in cellular FASs considering the characteristics of FAS, layout, and production factors.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2009.06a
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• pp.545-546
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• 2009

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2010.11a
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• pp.873-874
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• 2010

• Korean Journal of Computational Design and Engineering
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• v.2 no.2
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• pp.93-102
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• 1997

Most design changes are due to interferences and fit-up as parts are assembled if such a large product as an automobile or an aircraft is developed by many concurrent engineers. In this part (1) of the thesis, the assembly-centric modeling methodology with CAD systems is proposed in order to reduce the design changes. Unlike part-centric modeling method, a part is modeled with its own coordinate system which is used in downstream process as machining and measuring. The part coordinates initially have the same orientation as its assembly which is predefined in BOM (Bill of Material). Then, the corrdinates origin of the part is moved to its location to be assembled from that of its assembly coordinate system. To implement this methodology, the position data of the part w.r.t. its assembly are stored in a database to build the same hierarchical assembling structure as BOM structure. This modeling approach has the advantage of reflecting asembling sequence, because the process of positioning parts is similar to that of real assembling. And with the method, a designer can easily adjust all of the part positions of an assembly to resolve interferences if he modifies just the coordinates origin of the assembly, which results in moving included parts and assemblies together.

• Korean Journal of Computational Design and Engineering
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• v.2 no.2
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• pp.103-110
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• 1997

In the development of large complex assembly, most design changes are from the following reasons.: 1) insufficient consideration of assembling sequence of downstream process. 2) interference and fit-up of related parts. 3) initial design changes which are not completely resolved. In order to reduce the first reason of above, the assembly-centric modeling methodology was proposed in the part (1) of the thesis. In this part (2), a Digital Mock-Up system, which is a tool to build a virtual mock-up in design stage, has been developed in order to prevent the other two reasons. The system can build a virtual assembly in various ways as followings.: 1) assembling parts which are located in user defined envelope. 2) assembling parts with the specified disciplines. 3) assembling parts that are selected in the part list. It can also make an assembly by the combination of above methods. In addition to that, it has the functions to read/write the virtual assembly and to explode parts of the assembly in desired direction. With the virtual assembly, engineers can design interference free parts without making physical mock-up. The system has been implemented with Oracle database management system in CATIA environment.

• Korean Management Science Review
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• v.13 no.2
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• pp.25-48
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• 1996

Mixed Model Assembly Lines (MMALs) are increasingly used to produce differentiated products on a single assembly line without work-in-process storage, Usually, a typical MMAL consists of a number of (1) stations doing exactly the same operation on every job, (2) stations involving operations with different choices, and (3) stations offering operations that are not performed on every job, or that are performed on every job but with many options. For stations of the first type there is no sequencing problem at all. However, for the second type a set-up cost is incurred each time the operation switches from one choice to another. At the third type of stations, different models, requring different amounts and choices of assembly work, creates an uneven flow of work along the line and variations in the work load at these stations. When a subsequence of jobs requires more work load than the station can handle, it is necessary to help the operations at the station or to complete the work elsewhere. Therefore, a schedule which minimize the sum of set-up cost and utility work cost is desired. So this study has developed Fixed Random Ordering Rule (FROR), Fixed Ascending Ordering Rule (FAOR), Fixed Descending Ordering Rule, and Extended NHR (ENHR). ENHR is to choose optimal color ordering of each batch with NHR, and to decide job sequence of the batch with it, too. As the result of experiments, ENHR was the best heuristic algorithm. NHR is a new heuristic rule in which only the minimum addition of violations from both partial sequence and unassigned sequence at every branch could be considered. And this is a heuristic sequencing rule for the third type of stations at MMAL. This study developed one more heuristic algorithm to test the performance of NHR, which is named as Practical Heuristic Rule (PHR).

• Journal of Korean Institute of Industrial Engineers
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• v.28 no.3
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• pp.264-273
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• 2002

This paper focuses on disassembly sequencing, which is the problem of determining the optimum disassembly level and the corresponding disassembly sequence for a product at its end-of-life with the objective of maximizing the overall profit. In particular, sequence-dependent operation times, which frequently occur in practice due to tool-changeover, part reorientation, etc, are considered in the parallel disassembly environment. To represent the problem, a modified directed graph of assembly states is suggested as an extension of the existing extended process graph. Based on the directed graph, the problem is transformed into the shortest path problem and formulated as a linear programming model that can be solved straightforwardly with standard techniques. A case study on a photocopier was done and the results are reported.