• Proceedings of the Korean Society of Precision Engineering Conference
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• 1994.10a
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• pp.743-747
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• 1994

A process planning system that generates alternative process plans offers multiple process plans for a part, thereby provides the flexibility to cope with the changes in shop floor status. In this paper, we introduce the concept of process net as a model for the generation of alternative process plans. We also show the usefulness of process net model by implementing the developed system to generate alternative process plans for rotational parts.

• Journal of the Korean Society for Precision Engineering
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• v.14 no.1
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• pp.168-173
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• 1997

A process planning system that generates alternative process plans offers multiple process plans for a part, thereby provides the flexibility to cope with the changes in shop floor status. In this paper, we intro- duce the concept of process net as a model for the generation of alternative process plans. We also show the usefulness of process net model in generating alternative process plans by implementing the developed sys- tem to construct process net, and devising an algorithm to generate alternative process plans for rotational parts.

• Journal of the Korea Society for Simulation
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• v.10 no.1
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• pp.51-62
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• 2001

For the productivity improvement, it is necessary to analyze problem of the system and evaluate alternative plans. But, it if hard to experiment and evaluate alternative plans in real existing system. Therefore, it is necessary to synthetically analyze and evaluate alternative plans using simulation and statistical analysis method. In this case study, as a simulation language, Promodel is used to compare and evaluate four alternatives which are considered to improve the productivity of an object system. The object system is constituted of a pretreatment line and a painting line. The purpose of this study is to analyze whether the decrease of the down time in pretreatment line can be effective to the productivity improve comparing with exiting system and other alternatives. The other purpose is to choose an alternative that has the best productivity improvement. The results of the simulation show that the possibility of improvement in productivity by decreasing the down time of pretreatment line. Two-Stage Bonferroni Procedure is used to choose the best alternative.

• Journal of the Korean Society for Precision Engineering
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• v.15 no.12
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• pp.72-80
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• 1998

In this study, a design approach based on genetic algorithm is proposed to solve the manufacturing cell design problem considering alternative process plans and alternative machines. The problem is formulated as a 0-1 integer programming model which considers several manufacturing parameters, such as demand and processing time of part, machine capacity, manufacturing cell size, and the number of machines in a machine cell. A genetic algorithm is used to determine process plan for each part, part family and machine cell simultaneously.

• Journal of the Korean Society of Clothing and Textiles
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• v.26 no.11
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• pp.1582-1592
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• 2002

The purpose of this study is to suggest production planning model for women's apparel manufacturer, which are relevant to the situation of Korean clothing industry. The research was based on simulation method. The basic model for the simulation was developed based on the empirical data from six production fm. After verifying the basic model, low alternative production plans went through trial run. In order to suggest the application of these alternative production plans for various style numbers and lot sizes, the simulation results were compared in terms of product efficiency and product cost. The four alternative plans were as follows: 1. The first alternative was to spread out work loads among workers in order to resolve bottlenecks in work flow. So this was suited to manufacturers that had constant production without regard to changing seasons. 2. The second alternative was to merge the skirt and trouser production, which require less work load, in one line. In this line, a few machine was justified by production improvement. It was suited to cases which producted various style suits. The third and fourth alternative were using another subcontractor for assembling inner shell garments. These was compatible in manufacturers which had to product more styles and sizes of trousers and skirts than those of upper garments. 3. The third alternative was to reassign the same workers in production line. Thus, production was increased. 4. The fourth alternative was to except two worker in production line, so expenses of worker's wage was decreased. The four alternatives could be one of the cost effective manufacturing plans according to manufacturer situations.

• Proceedings of the KIEE Conference
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• 1996.07b
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• pp.871-874
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• 1996

It is practically very important in multi-criteria long-tenn IRP process to develop the set of candidate resource plans that meet following two conditions. First, the number of resource plans should not be too large for computer job. Second, the unknown best plan should exist among the set of candidate plans. In this paper, several novel procedures are developed. The main idea of the procedures is the two-stage approach. The first stage is to find the set of feasible resource capacity mixes in given target year(s). And, the second stage is to find the set of alternative paths of resource options for each resource mix determined in the first stage.

• Journal of the Korean Operations Research and Management Science Society
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• v.30 no.3
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• pp.55-65
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• 2005

In recent manufacturing systems, most jobs may have several process plans, such as alternative sequence of operations, alternative machine etc. A few researches have addressed the necessity for the integration of process planning and scheduling function for efficient use of manufacturing resources. But the integration problem is very difficult and complex. Many prior researches considered them separately or sequentially. It introduces overlapping or partial duplications in solution efforts. In this paper, Integration problem of jobs with multiple process plans in a job shop environment Is addressed. In order to achieve an efficient integration between process planning and scheduling by taking advantage of the flexibility that alternative process plans offer, we designed GA(Genetic Algorithm)-based scheduling method. The performance of proposed GA is evaluated through comparing integrated scheduling with separated scheduling in real world company with alternative machines and sequences of operations. Also, a couple of benchmark problems are used to evaluate performance. The integrated scheduling method in this research can be effectively epplied to the real case.

• Journal of the Korean Regional Science Association
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• v.14 no.2
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• pp.107-126
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• 1998

Since the election of governors and mayors by vote, many local governments in Korea establish long-range plans for their regional development. The major purposes of the plans are to set up development path for their communities and to devise economic development strategies. But most of the plans established thus formulated by the same method utilized in centralized political regime. This method is considered no longer appropriate to devise the long-range development plans for local government especially in the era of globalization and localization, where local governments behave independently, where local governments behave independently competition. We suggest an alternative way to establish such plans, based on the method employed in business sector. The plans, formulated in this way, are called strategy oriented long-range development plans. The underlying logic for the plans is non-linear one. The plans are issue oriented and focus more on process than outcome. Given that these features are properly incorporated in the plans, we expect that the strategy oriented long-range development plans can be genuine guidelines for local economic development in the years to come.

• Journal of Computing Science and Engineering
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• v.3 no.1
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• pp.27-58
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• 2009

Aggregation join queries are an important class of queries over data streams. These queries involve both join and aggregation operations, with window-based joins followed by an aggregation on the join output. All existing research address join query optimization and aggregation query optimization as separate problems. We observe that, by putting them within the same scope of query optimization, more efficient query execution plans are possible through more versatile query transformations. The enabling idea is to perform aggregation before join so that the join execution time may be reduced. There has been some research done on such query transformations in relational databases, but none has been done in data streams. Doing it in data streams brings new challenges due to the incremental and continuous arrival of tuples. These challenges are addressed in this paper. Specifically, we first present a query processing model geared to facilitate query transformations and propose a query transformation rule specialized to work with streams. The rule is simple and yet covers all possible cases of transformation. Then we present a generic query processing algorithm that works with all alternative query execution plans possible with the transformation, and develop the cost formulas of the query execution plans. Based on the processing algorithm, we validate the rule theoretically by proving the equivalence of query execution plans. Finally, through extensive experiments, we validate the cost formulas and study the performances of alternative query execution plans.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.28 no.1B
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• pp.33-40
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• 2008

Intensive rainfalls in wet season (June~September) result in serious flood damage which is about 95% of natural hazard in Korea. Recently, in order to cope with repeated flood hazard, comprehensive flood control plans have been carried out in large basins in Korea. The plans suggest structural alternative plans for flood mitigation as well as non-structural plans. In this study, a practical method using a decision tree was developed to systematically allocate structural facilities for flood control, which maximizes the flood control capacity in a basin. This study also presents a practical guidance to organize structural defensive alternatives for a comprehensive flood control plan in a large basin.