• 제어로봇시스템학회:학술대회논문집
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• 2003.10a
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• pp.428-432
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• 2003

Quantitative Feedback Theory (QFT) is one of most effective methods of robust controller design and can be considered as a suitable method for systems with parametric uncertainties. Particularly it allows us to obtain controllers less conservative than other methods like $H_{\infty}$ and ${\mu}$-synthesis. In QFT method, we transform all the uncertainties and desired specifications to some boundaries in Nichols chart and then we have to find the nominal loop transfer function such that satisfies the boundaries and has the minimum high frequency gain. The major drawback of the QFT method is that there is no effective and useful method for finding this nominal loop transfer function. The usual approach to this problem involves loop-shaping in the Nichols chart by manipulating the poles and zeros of the nominal loop transfer function. This process now aided by recently developed computer aided design tools proceeds by trial and error and its success often depends heavily on the experience of the loop-shaper. Thus for the novice and First time QFT user, there is a genuine need for an automatic loop-shaping tool to generate a first-cut solution. In this paper, we approach the automatic QFT loop-shaping problem by using an algorithm involving Linear Programming (LP) techniques and Genetic Algorithm (GA).

• Journal of Korean Society of Forest Science
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• v.88 no.2
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• pp.273-281
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• 1999

In this study, linear programming (LP) was applied to solving for optimal harvesting schedules of multiple-use forest management in Mt. Kari area managed by Chunchun National Forest Station. Associated with the geographic characteristics, the study area was classified into 4 large management units or watersheds and simultaneously applied were the site-specific levels of management constraints : nondeclining yield, initial cut for existing stands, % cut area, the volume of soil erosion, timber production and carbon storage, ending inventory condition and % area species selection for regeneration. The problem was formulated using both Model I and Model II techniques. In this paper, the formulations are presented and the results of the optimal solutions are discussed for comparison purposes.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.40 no.11
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• pp.62-72
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• 2003

This paper deals with a crosstalk minimization method by wire spacing. The suggested method uses linear programming method and consider crosstalk of both horizontal segments and vertical segments. In this paper, we suggest a method which can predict the coupling length between vertical segments in the final routing result using longest path algorithm. By the suggested method, we can make LP problem without integer variable. Therefore, it is much faster to solve the problem. In the case of crosstalk optimization, the suggested method optimized peak crosstalk 11.2%, and 3% total crosstalk more than wire perturbation method. The execution time of the suggested method is as fast as it takes 11 seconds when Deutsch is optimized.

• Proceedings of the Korean Operations and Management Science Society Conference
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• 2002.05a
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• pp.1044-1051
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• 2002

This paper proposes a two-phase mathematical programming approach by considering classification gap to solve the proposed credit scoring problem so as to complement any theoretical shortcomings. Specifically, by using the linear programming (LP) approach, phase 1 is to make the associated decisions such as issuing grant of credit or denial of credit to applicants. or to seek any additional information before making the final decision. Phase 2 is to find a cut-off value, which minimizes any misclassification penalty (cost) to be incurred due to granting credit to 'bad' loan applicant or denying credit to 'good' loan applicant by using the mixed-integer programming (MIP) approach. This approach is expected to and appropriate classification scores and a cut-off value with respect to deviation and misclassification cost, respectively. Statistical discriminant analysis methods have been commonly considered to deal with classification problems for credit scoring. In recent years, much theoretical research has focused on the application of mathematical programming techniques to the discriminant problems. It has been reported that mathematical programming techniques could outperform statistical discriminant techniques in some applications, while mathematical programming techniques may suffer from some theoretical shortcomings. The performance of the proposed two-phase approach is evaluated in this paper with line data and loan applicants data, by comparing with three other approaches including Fisher's linear discriminant function, logistic regression and some other existing mathematical programming approaches, which are considered as the performance benchmarks. The evaluation results show that the proposed two-phase mathematical programming approach outperforms the aforementioned statistical approaches. In some cases, two-phase mathematical programming approach marginally outperforms both the statistical approaches and the other existing mathematical programming approaches.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.8 no.2
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• pp.443-461
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• 2014

Overlay routing has emerged as a promising approach to improve reliability and efficiency of the Internet. For one-hop overlay source routing, when a given primary path suffers from the link failure or performance degradation, the source can reroute the traffic to the destination via a strategically placed relay node. However, the over-heavy traffic passing through the same relay node may cause frequent package loss and delay jitter, which can degrade the throughput and utilization of the network. To overcome this problem, we propose a Load-Balanced One-hop Overlay Multipath Routing algorithm (LB-OOMR), in which the traffic is first split at the source edge nodes and then transmitted along multiple one-hop overlay paths. In order to determine an optimal split ratio for the traffic, we formulate the problem as a linear programming (LP) formulation, whose goal is to minimize the worse-case network congestion ratio. Since it is difficult to solve this LP problem in practical time, a heuristic algorithm is introduced to select the relay nodes for constructing the disjoint one-hop overlay paths, which greatly reduces the computational complexity of the LP algorithm. Simulations based on a real ISP network and a synthetic Internet topology show that our proposed algorithm can reduce the network congestion ratio dramatically, and achieve high-quality overlay routing service.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.12 no.4
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• pp.1565-1574
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• 2011

Scheduling of die casting is a procedure of determining quantities of cast products so as to optimize a predetermined performance criterion. This paper presents a novel scheme of preventing product shortage raised by defective castings when die casting scheduling is applied to real casting operations. The previously developed linear programming (LP) model for die casting scheduling maximizes the average efficiency of melting furnaces in regard of the usage of molten alloy. However, the LP model is not able to cope with the problem of defective products occurring in the casting process. The proposed scheme is that whenever defective products are found in a shift, the foundryman produces additional cast products using the residue of molten alloy left at the end of the next shift. Neither the calculated amount of molten alloy nor the scheduling result of the LP model does not have to be altered for this method. The simulation result demonstrates the superiority and applicability of the newly proposed scheme.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.13 no.8
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• pp.3358-3365
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• 2012

This paper presents a scheduling scheme for die casting processes considering power usage. The scheduling problem of a shift-based die casting process is represented by a linear programming (LP) model that maximizes the average efficiency of melting furnaces in regard of the usage of molten alloy, where the product quantities of each shift are used as primary variables. In this research, we propose a novel LP model that considers power usage of foundries. The developed LP model can derive product plans in which the expended power of a casting shift does not exceed a prescribed limit, while optimizing the efficiency of alloy usage. The simulation result of a case study demonstrates the superiority and applicability of the proposed scheme. This paper serves as a basic research on the role of foundries as an intelligent costumer in smart grid environment where the limit of power usage should be fulfilled.

• Journal of Korea Society of Industrial Information Systems
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• v.15 no.5
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• pp.187-196
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• 2010

We present a link that allows Excel to call the functions in the lp_solve system. lp_solve is free software licensed under the GPL that solves linear and mixed integer linear programs of moderate size. Our link manages the interface between Excel and lp_solve. Excel has a built-in add-in named Solver that is capable of solving mixed integer programs, but only with fewer than 200 variables. This link allows Excel users to handle substantially larger problems at no extra cost. Futhermore, we introduce that a network drawing method in Excel using arc adjacency lists of a network.

• Biotechnology and Bioprocess Engineering:BBE
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• v.7 no.3
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• pp.171-177
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• 2002

The metabolic flux pattern for L-histidine production was analyzed when glucose and/or acetate were used as carbon sources. Total L-histidine production was enhanced when mixed substrate (glucose and acetate) was used, compared wish that when either glucose or acetate was used as the sole carbon source. Theoretical maximum carbon fluxes through the main pathways for L-histldine production, cell growth, and ATP consumption for cell maintenance were obtained by the linear programming (LP) method. By comparison of the theoretical maximum carbon fluxes tilth actual ones, it was found that a large amount of glucose was actually used for maintenance of cell viability. On the other hand, acetate was used for cell growth. After depletion of acetate in the mixed substrate culture, the flux for glucose to L-histldine synthesis was markedly enhanced. A strategy for effective L-histidine production using both carbon sources was proposed.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.65 no.12
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• pp.1965-1970
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• 2016

This paper studies generator rescheduling technique for congestion management in power system with wind farms. The proposed technique is formulated to minimize the rescheduling cost of conventional and wind generators to alleviate congestion subject to operational line overloading. The generator rescheduling method has been used with incorporation of wind farms in the power system. The locations of wind farms are selected based upon power transfer distribution factor (PTDF). Because all generators in the system do not need to participate in congestion management, the rescheduling has been done by generator selection based on the proposed generator sensitivity factor (GSF). The selected generators have been rescheduled using linear programming(LP) optimization techniques to alleviate transmission congestion. The effectiveness of the proposed methodology has been analyzed on IEEE 14-bus systems.