• Journal of Korean Society of Industrial and Systems Engineering
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• v.32 no.3
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• pp.118-126
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• 2009

This research investigates the problem of minimizing setup costs in resequencing jobs having first-in, first-out(FIFO) constraints at conveyorized production or assembly systems. Sequence changing at conveyor junctions in these systems is limited due to FIFO restriction. We first define the general problem of resequencing jobs to workstations satisfying precedence relationships between jobs(Generalized Sequential Ordering Problem, GSOP). Then we limit our scope to FIFO precedence relationships which is the conveyor selection problem at a diverging junction(Diverging Sequential Ordering Problem, DSOP), modeling it as a 0-1 integer program. With the capacity constraint removed, we show that the problem can be modeled as an assignment problem. In addition, we proposed and evaluated the heuristic algorithm for the case where the capacity constraint cannot be removed. Finally, we discuss the case study which motivated this research and numerical results.

• Industrial Engineering and Management Systems
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• v.4 no.2
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• pp.145-157
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• 2005

There are a lot of raw materials, work-in-processes and finished goods in manufacturing industry. Here, the less stock of materials and work-in-processes manufacturing industry has, the worse the rate of the production is. Inversely, the more manufacturing industry has, the more expensive the cost to support them is. Thus, it is important for us to balance them efficiently. In general, inventory problems are to decide appropriate times to produce goods and to determine appropriate quantities of goods. Therefore, inventory problems require as more useful information as possible. For example, there are demand, lead time, ordering point and so on. In this paper, we deal with an optimal ordering policy on both way substitutable two-commodity inventory control system. That is, there is a problem of how to allocate the produced two kinds of goods in a factory to m areas so as to minimize the total expected inventory cost. The demand of each area is probabilistic, and we adopt the exponential distribution as a probability density function of demand. Moreover, we provide numerical examples of the problem.

• Journal of KIISE:Software and Applications
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• v.34 no.6
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• pp.572-583
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• 2007

This paper investigates Centering-based metrics to evaluate ordering of utterances for text structuring. We point out a problem of MIN.NOCB metric which has been regarded as the simplest and best measure to evaluate coherence of ordering within Centering framework, and propose a new Centering-based metric, MAX.CPS as an alternative or supplementary one. This paper introduces a framework which pre-estimates the effectiveness of a metric on a given input ordering, and selects an applicable metric according to the pre-estimation result. Using this framework, we propose a new policy which can generate more optimal ordering within Centering framework. Moreover, we evaluate several kinds of Cf-ranking methods in terms of Centering-based metrics, and find that simply ranking entities by their linear order is generally the most suitable because of characteristics in Korean.

• Nonlinear Functional Analysis and Applications
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• v.28 no.3
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• pp.831-850
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• 2023

Our long-standing Metatheorem in Ordered Fixed Point Theory is applied to some well-known order theoretic fixed point theorems. In the first half of this article, we introduce extended versions of the Zermelo fixed point theorem, Zorn's lemma, and the Caristi fixed point theorem based on the Brøndsted-Jachymski principle and our 2023 Metatheorem. We show some of their applications to other fixed point theorems or theorems on the existence of maximal elements in partially ordered sets. In the second half, we collect and improve order theoretic fixed point theorems in the collection of Howard-Rubin in 1991 and others. In fact, we improve or extend several ordering principles or fixed point theorems due to Brézis-Browder, Brøndsted, Knaster-Tarski, Tarski-Kantorovitch, Turinici, Granas-Horvath, Jachymski, and others.

• Honam Mathematical Journal
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• v.38 no.3
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• pp.553-581
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• 2016

The purpose of this paper is to prove some fixed point theorems in a complete metric space equipped with a partial ordering using w-distances together with the aid of an altering functions and new functions of admissible type.

• Korean Management Science Review
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• v.15 no.1
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• pp.87-95
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• 1998

The computational speed of interior point method depends on the speed of Cholesky factorization. The supernodal column Cholesky factorization is a fast method that performs Cholesky factorization of sparse matrices with exploiting computer's characteristics. Three steps are necessary to perform the supernodal column Cholesky factorization : symbolic factorization, creation of the elimination tree, ordering by a post-order of the elimination tree and creation of supernodes. We study performing sequences of these three steps and efficient implementation of them.

• The Mathematical Education
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• v.25 no.3
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• pp.19-24
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• 1987

In this paper, we give a result that maximum principles including Zorn's lemma can be regarded as various types of fixed point theorems. Our main application is that the well-known ordering principles in nonlinear analysis including the Bishop-Phelps argument and a number of its generalizations can be converted to fixed point theorems and vice versa. Consequently, we obtain new results and unify many known results.

• ETRI Journal
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• v.24 no.4
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• pp.299-310
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• 2002

This paper describes an integrated network management framework for providing point-to-multipoint reservation service (PMRS) in an ATM network. There are two major issues confronting the network service provider in relation to this service: one is to rapidly confirm the acceptability of the subscriber's reservation at subscription time, and the other is to punctually activate the reserved point-to-multipoint service. To meet these requirements, we developed a service provision model (SPM) and a network resource model of a bandwidth allocation timetable (BATT). We propose a point-to-multipoint routing algorithm composed of ordering and backtracking procedures, which can find the best branch point under the complex network topology and can add more destinations to the existing point-to-multipoint route. We demonstrate the feasibility of the SPM, the BATT, and the point-to-multipoint routing algorithm by implementing our schemes and analyzing their performance under the operational ATM network of KT(Korea Telecom).

• Corrosion Science and Technology
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• v.22 no.3
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• pp.214-219
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• 2023

Considering the case in the United States where most nuclear power plants with an initial design life of 40 years continue to operate until 60 or 80 years after undergoing material soundness evaluation, it is time to plan a more robust long-term operation strategy for nuclear power plants in Korea. There are some reports that SRO/LRO might be formed when Alloy 690 is heat treated for 10,000 hours to 100,000 hours at 360 to 450 ℃. The possibility of LRO formation in Alloy 690 steam generator tubings of Kori nuclear power plant unit 1 (Kori-1) was investigated using existing research papers. The mechanism in which SRO/LRO occurred was also surveyed. Alloy 690 was found to be more likely to cause ordering than Alloy 600 in terms of alloy composition. The ordering could be evaluated through changes in material properties. However, it is difficult to evaluate it from a microstructural point of view. The likelihood of LRO in Alloy 690 of the Kori-1 plant operated at 320 ℃ for 19 years seemed to be low in terms of time and exposure temperature.

• Journal of the Korea Society for Simulation
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• v.12 no.3
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• pp.31-40
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• 2003

This paper studies an optimal policy for a certain class of (s, S) inventory control systems, where the demands are characterized by the renewal arrival process. To minimize the average cost over a simulation period, we apply a stochastic optimization algorithm which uses the gradients of parameters, s and S. We obtain the gradients of objective function with respect to ordering amount S and reorder point s via a combined perturbation method. This method uses the infinitesimal perturbation analysis and the smoothed perturbation analysis alternatively according to occurrences of ordering event changes. The optimal estimates of s and S from our simulation results are quite accurate. We consider that this may be due to the estimated gradients of little noise from the regenerative system simulation, and their effect on search procedure when we apply the stochastic optimization algorithm. The directions for future study stemming from this research pertain to extension to the more general inventory system with regard to demand distribution, backlogging policy, lead time, and inter-arrival times of demands. Another direction involves the efficiency of stochastic optimization algorithm related to searching procedure for an improving point of (s, S).