• Journal of IKEEE
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• v.13 no.1
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• pp.71-76
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• 2009

As one of the most important requirements for wireless sensor networks, prolonging network lifetime can be realized by minimizing energy consumption in cluster heads as well as sensor nodes. While most of the previous researches have focused on the energy of sensor nodes, we devote our attention to cluster heads because they are most dominant source of power consumption in the cluster-based sensor networks. Therefore, we seek to minimize energy consumption by minimizing the maximum(MINMAX) energy dissipation at each cluster heads. This work requires energy-efficient clustering of the sensor nodes while satisfying given energy constraints. In this paper, we present a constraint satisfaction modeling of cluster-based routing in a heterogeneous sensor networks because mixed integer programming cannot provide solutions to this MINMAX problem. Computational experiments show that substantial energy savings can be obtained with the MINMAX algorithm in comparison with a minimum total energy(MTE) strategy.

• Journal of Institute of Control, Robotics and Systems
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• v.10 no.2
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• pp.164-170
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• 2004

Recently, the demand for micro hard disk drive that provides high-capacity removable storage for handhold electronic devices is growing very rapidly Reducing power consumption is one of the primary control objectives in micro disk drives. The input power delivered to the seek servo system is consumed as heat by the transistors of power amplifier and motor coil resistance. In this paper, we present a new seek servo controller for minimizing the power consumption. We use a Fourier decomposition and nonlinear programming to determine the optimum seek profile that minimizes the power consumption. Also, the trajectory tracking controller is developed for exact tracking of the optimum seek profile. Finally, we present some experimental results using a commercially available micro disk drive in order to demonstrate the superior performance of the proposed controller.

• Proceedings of the KSR Conference
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• 2011.10a
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• pp.1743-1753
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• 2011

Seoul Metropolitan Government has performed alternative transit system, light rail transit(LRT), for settling the problems of urban public transit system based on conventional bus service and heavy rail transit(HRT). LRT projects of total 8 lines(about 73.6km), including Ui-Sinseol line, have been planned as Build-Transfer-Operate(BTO) projects. For the first LRT, Ui-Sinseol line, however, design of structure had met standard for design of HRT, because of no domestic design code for LRT when participates of Ui-Sinseol project submitted the design proposal. This case study reports a successful example of LRT design minimizing the scale of stations designed in base of HRT code. The problems, like oversized structures compared with LRT vehicles, excessive costs for construction, had been resolved through negotiations with the participates of Ui-Sinseol line. Result suggests that present and future costs for construction and maintenance of the LRT projects in Seoul be considerably reduced in advance.

• Journal of Industrial Technology
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• v.28 no.A
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• pp.51-61
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• 2008

In these days, domestic manufacturers are faced with managerial difficulties such as the increasing competition in their industry and the increasing power of customers. In this situation, they have to satisfy their customers with high quality of their products and meeting due date of their orders. Production of the order within due date is an important factor for improving enterprise competitiveness. The causes of occurrence of tardiness may be wrong product scheduling, unexpected events in field and so on, a way to minimize tardiness is use of alternative machines, overwork, outsourcing and etc.. In this study, we deal with a scheduling problem that can minimize tardiness using alternative machines. This paper provides a mathematical program and a heuristic method for job shop scheduling for minimizing tardiness with alternative machines. And a proposed heuristic method is verified comparing with optimal solution obtained by ILOG CPLEX.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2003.10a
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• pp.201-206
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• 2003

Plastic injection mould have two kinds of trouble, one is in mould another in injection parts. Most of defects of the former take the cause in a design like in structure and working, the later weld line, transforming, sink mark, burning, flow mark, scratching, shading, black hole and so on. Most of problems of the later is difficult for making a clear definitely the reason of defects because of complexible. The purpose of this paper is to improve the quality of plastic injection mould and parts with inquiring the counter plan and rouble of the part of Flat TV Front Cover by flow control method and gas- assisted injection moulding. For minimizing defects from injection moulding parts, this paper was investigated with using computer aided injection mold filling simulations. Based on these numerical results, I established guidelines mould design and injection processing condition. As a results I got the improve of quality, minimizing surface defects moulded parts and troubles in mould.

• International Journal of Fuzzy Logic and Intelligent Systems
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• v.16 no.2
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• pp.81-86
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• 2016

Term weighting is a popular technique that effectively weighs the term features to improve accuracy in document classification. While several successful term weighting algorithms have been suggested, none of them appears to perform well consistently across different data domains. In this paper we propose several reasonable methods to combine different term weight vectors to yield a robust document classifier that performs consistently well on diverse datasets. Specifically we suggest two approaches: i) learning a single weight vector that lies in a convex hull of the base vectors while minimizing the class prediction loss, and ii) a mini-max classifier that aims for robustness of the individual weight vectors by minimizing the loss of the worst-performing strategy among the base vectors. We provide efficient solution methods for these optimization problems. The effectiveness and robustness of the proposed approaches are demonstrated on several benchmark document datasets, significantly outperforming the existing term weighting methods.

• Journal of Korean Society of societal Security
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• v.1 no.2
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• pp.87-92
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• 2008

This paper investigates the corrosion property of sprinkler pipe and provides the prevention solution. This study examines the property of stainless pipe widely used as sprinkler pipe and performs theoretical studies on the corrosion procedure. It was found that corrosion of the pipes mainly results from deterioration of pipe and wrong installation. The test result is expected to be useful in designing of the pipe system and minimizing of the corrosion.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2002.05a
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• pp.382-386
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• 2002

The tapping is machining process that makes a female screw on the parts to be assembly together. It is used for the high-speed tapping machine with synchronizing function for the high productivity. This paper describes the development of the ultra high-speed tapping machine with 10,000rpm. The key factors in the tapping speed are the acceleration/deceleration velocity and the synchronizing errors between the spindle motor and feeding motor. To minimizing acceleration/deceleration time, the low inertia spindle with synchronous built-in servo motor is developed. To minimizing synchronizing errors, the tapping cycle algorithm under open architecture CNC environment is optimized. The developed tapping machine has 0.13sec/10,000rpm in acceleration/deceleration time and the synchronizing error below 4.0%. It has 0.55sec for cycle time of one female screw, M3 tap, 2 times depth of tap diameter.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.33 no.4
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• pp.45-57
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• 2010

This paper considers a 2-stage assembly flowshop scheduling problem where each job is completed by assembling multiple components. The problem has the objective measure of minimizing total completion time. The problem is shown to be NP-complete in the strong sense. Thus, we derive some solution properties and propose three heuristic algorithms. Also, a mixed-integer programming model is developed and used to generate a lower bound for evaluating the performance of proposed heuristics. Numerical experiments demonstrate that the proposed heuristics are superior over those of previous research.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.33 no.4
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• pp.1-9
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• 2010

In this paper, we consider a two-machine re-entrant permutation flowshop scheduling problem with the objective of minimizing total flowtime, and suggest branch and bound algorithms for the scheduling problem. In this scheduling problem, each job must be processed twice on each machine, that is, each job should be processed on the two machines in the order of machine 1, machine 2 and then machine 1 and machine 2. In this research, based on the results of existing researches for re-entrant permutation flowshop scheduling problems, various dominance properties, lower bound and heuristic algorithm are suggested for the problem, and those are used to develop branch and bound algorithms. In the computational experiments for evaluation of the performance of the algorithms, the suggested branch and bound algorithms are tested on randomly generated test problems and results are reported.