• Journal of Advanced Marine Engineering and Technology
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• v.35 no.3
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• pp.335-340
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• 2011

Building energy saving is one of the most important issues in these days. Control algorithm for energy saving should be designed properly to reduce power consumption in building. Recently, building energy system consists of hybrid energy system coupling with RE (Renewable Energy) source. In this paper, an optimum control algorithm for building energy saving is applied to BEMS (Building Energy Management System) by using an outdoor air temperature prediction strategy. BEMS coupling with renewable energy can control HVAC (Heating, Ventilating and Air-Conditioning) system effectively. In order to verify the effectiveness of building energy saving, BEMS was tested for several months at a laboratorial chamber with an air conditioner, fan and heater. To this end BEMS embedded control algorithm has been tested successfully.

• Journal of Mechanical Science and Technology
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• v.18 no.8
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• pp.1358-1367
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• 2004

As a part II of theis research, new local inspection planning strategy is proposed in this paper based on the proposed inspection feature extraction method. In the local inspection planning stage, each feature is decomposed into its constituent geometric elements for more effective inspection planning. The local inspection planning for the decomposed features are performed to determine: (1) the suitable number of measuring points, (2) their locations, and (3) the optimum probing paths to minimize measuring errors and times. The fuzzy set theory, the Hammersley's algorithm and the TSP method are applied for the local inspection planning. Also, a new collision checking algorithm is proposed for the probe and/or probe holder based on the Z-map concept. Finally, the results are simulated and analyzed to verify the effectiveness of the proposed methods.

• Transactions of the Korean Society of Automotive Engineers
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• v.10 no.1
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• pp.115-124
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• 2002

The optimum design of auto-catalyst needs a good compromise between the pressure drop and flow distribution in the monolith. One of the effective methods to achieve this goal is to use the concept of radially variable cell density. However, there has been no study of evaluating the usefulness of this method on light-off catalyst. We have computationally investigated the effectiveness of variable cell density technique applied to the light-off catalyst using a three-dimensional integrated CFD model. in which transient chemical reacting calculations are involved. Computed results show that variable cell density technique can reduce the accumulated emissions of CO and HC during the early 100sec of FTP cycle by 86.78 and 80.87%, respectively, The effect of air-gap between the monoliths has been also examined. It is found that air-gap has a beneficial effect on reducing pressure drop and cold-start emissions.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.22 no.12
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• pp.873-880
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• 2010

The present study developed a computer simulation program to determine the optimum strategy and capacity of a micro combined heat and power(CHP) system. This simulation program considered a part-load electrical/thermal efficiency and transient response characteristics of CHP unit. The result obtained from the simulation was compared with the actual operation of 30 kW gas engine driven micro CHP system. It was found that the simulation could reproduce the daily operation behavior, such as operating hours and mean load factor, closely to the actual behavior of the system and could predict the amount of electrical/thermal output and fuel consumption with the error of less than 12%.

• Proceedings of the Korean Operations and Management Science Society Conference
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• 1997.10a
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• pp.193-196
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• 1997

In this paper we consider a Bayesian theoretic approach to periodic incomplete preventive maintenance with minimal repair at failure. We assume that the system failure rate is increasing as the frequency of PM increases and that the system is replaced at the K-th PM under this maintenance strategy. The optimal policies which minimize the expected cost rates are discussed. We seek the optimal periodic PM interval x and replacement time K under a Weibull failure intensity. Assuming suitable prior distribution for the Weibull parameters, we derive the posterior distribution incorporating failure data and obtain the updated optimal replacement strategies.

• Journal of Korean Institute of Industrial Engineers
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• v.23 no.3
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• pp.451-467
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• 1997

Tabu search (TS) is a useful strategy that has been successfully applied to a number of complex combinatorial optimization problems. By guiding the search using flexible memory processes and accepting disimproved solutions at some iterations, TS helps alleviate the risk of being trapped at a local optimum. In this article, we propose TS-based heuristics for solving a class of clustering problems, and compare the relative performances of the TS-based heuristic and the simulated annealing (SA) algorithm. Computational experiments show that the TS-based heuristic with a long-term memory offers a higher possibility of finding a better solution, while the TS-based heuristic without a long-term memory performs better than the others in terms of the combined measure of solution quality and computing effort required.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2002.11b
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• pp.12-16
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• 2002

Dynamic characteristics of smart laminated composite plates with passive constrained layer damping have been investigated to design structure with maximum possible damping capacity. The equations of motion are derived for flexural vibrations of symmetrical, multi-layer laminated plates. The damping ratio and modal damping of the first bending and torsional modes are calculated by means of iterative complex eigensolution method. The structural damping index(SDI) is introduced to determine the optimum placement of viscoelastic patch. This paper addresses a design strategy of laminated composite plate under vibrations.

• Journal of Korean Institute of Industrial Engineers
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• v.30 no.3
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• pp.241-249
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• 2004

By committing to a long-term replenishment contract, suppliers can mitigate the pressure to find new customers and afford to charge a discounted price to buyers seeking to lower their purchasing costs. In this paper, we develop an analytical model from buyer's perspective for the contracting process to investigate the buyer-supplier interactions. Based on the developed model, we propose an algorithm to derive optimal strategy for the contract. We consider a system with a single buyer and a supplier in a situation where the buyer's inventory is controlled by (R, S) policy under VMI setting. According to the contract, the supplier should replenish the buyer's inventory up to a fixed level every R times during a specified period. The buyer purchases any deficient amount from a spot market at a higher price. We show by computational experiment that our proposed algorithm finds the global optimum solution.

• Journal of Microbiology and Biotechnology
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• v.16 no.7
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• pp.1139-1143
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• 2006

Various techniques and strategies have been developed for the identification of intracellular metabolic conditions, and among them, isotope balance-based flux analysis with gas chromatography/mass spectrometry (GC/ MS) has recently become popular. Even though isotope balance-based flux analysis allows a more accurate estimation of intracellular fluxes, its application has been restricted to relatively small metabolic systems because of the limited number of measurable metabolites. In this paper, a strategy for incorporating isotope balance-based flux data obtained for a small network into metabolic flux analysis was examined as a feasible alternative allowing more accurate quantification of intracellular flux distribution in a large metabolic system. To impose GC/MS based data into a large metabolic network and obtain optimum flux distribution profile, data reconciliation procedure was applied. As a result, metabolic flux values of 308 intracellular reactions could be estimated from 29 GC/ MS based fluxes with higher accuracy.

• Structural Engineering and Mechanics
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• v.46 no.3
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• pp.403-416
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• 2013

This paper describes new optimization strategy that offers significant improvements in performance over existing methods for geometry design of frame structures. In this study, an imperialist competitive algorithm (ICA) and ant colony optimization (ACO) are combined to reach to an efficient algorithm, called Imperialist Competitive Ant Colony Optimization (ICACO). The ICACO applies the ICA for global optimization and the ACO for local search. The results of optimal geometry for three benchmark examples of frame structures, demonstrate the effectiveness and robustness of the new method presented in this work. The results indicate that the new technique has a powerful search strategies due to the modifications made in search module of ICACO. Higher rate of convergence is the superiority of the presented algorithm in comparison with the conventional mathematical methods and non hybrid heuristic methods such as ICA and particle swarm optimization (PSO).