• ETRI Journal
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• v.32 no.1
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• pp.1-10
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• 2010

In this paper, we present a fast Fourier transform (FFT) processor with four parallel data paths for multiband orthogonal frequency-division multiplexing ultra-wideband systems. The proposed 128-point FFT processor employs both a modified radix-$2^4$ algorithm and a radix-$2^3$ algorithm to significantly reduce the numbers of complex constant multipliers and complex booth multipliers. It also employs substructure-sharing multiplication units instead of constant multipliers to efficiently conduct multiplication operations with only addition and shift operations. The proposed FFT processor is implemented and tested using 0.18 ${\mu}m$ CMOS technology with a supply voltage of 1.8 V. The hardware- efficient 128-point FFT processor with four data streams can support a data processing rate of up to 1 Gsample/s while consuming 112 mW. The implementation results show that the proposed 128-point mixed-radix FFT architecture significantly reduces the hardware cost and power consumption in comparison to existing 128-point FFT architectures.

• Journal of applied mathematics & informatics
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• v.42 no.3
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• pp.625-634
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• 2024

The thrust of this paper is to extend the notion of Plithogenic vertex domination to the basic operations in Plithogenic product fuzzy graphs (PPFGs). When the graph is a complete PPFG, Plithogenic vertex domination numbers (PVDNs) of its Plithogenic complement and perfect Plithogenic complement are the same, since the connectivities are the same in both the graphs. Since extra edges are added to the graph in the case of perfect Plithogenic complement, the PVDN of perfect Plithogenic complement is always less than or equal to that of Plithogenic complement, when the graph under consideration is an incomplete PPFG. The maximum and minimum values of the PVDN of the intersection or the union of PPFGs depend upon the attribute values given to P-vertices, the number of attribute values and the connectivities in the corresponding PPFGs. The novelty in this study is the investigation of the variations and the relations between PVDNs in the operations of Plithogenic complement, perfect Plithogenic complement, union and intersection of PPFGs.

• Proceedings of the Korean Operations and Management Science Society Conference
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• 2007.11a
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• pp.388-394
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• 2007

In wireless network, we propose a predictive location update scheme which considers mobile user's(MU's) mobility patterns. MU's mobility patterns can be found from a movement history data. The prediction accuracy and model complexity depend on the degree of application of history data. The more data we use, the more accurate the prediction is. As a result, the location management cost is reduced, but complexity of the model increases. In this paper, we classify MU's mobility patterns into four types. For each type, we find the respective optimal number of application of history data, and predictive location area by using the simulation. The optimal numbers of four types are shown to be different. When we use more than three application of history data, the simulation time and data storage are shown to increase very steeply.

• Proceedings of the Korean Operations and Management Science Society Conference
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• 1996.10a
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• pp.53-56
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• 1996

The conventional inventory models are concerned with the items of which utilities and amount of numbers are constant over time. But in practice the items in inventory systems are increasing or decreasing. This study is concerned with the development of ameliorating inventory models. The ameliorating inventory is the inventory of goods whose utility increases over the time by ameliorating activation. The term ameliorating inventory is used in this paper at least, since the terminology is not standard well known. This study is performed according to areas; one is an economic order quantity(EOQ) model for the items whose utility is ameliorating in accordance with Weibull distribution, and the other is a partial selling quantity(PSQ) model developed for selling surplus inventory accumulated by ameliorating activation. Computer programs are developed to obtain the optimal ordering and selling quantity. Numerical examples to illustrate the effect of ameliorating rate on inventory polices are shown at the end of this paper.

• Journal of the Korean Operations Research and Management Science Society
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• v.29 no.2
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• pp.45-57
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• 2004

The purpose of this paper is studying the valuation of option prices in Incomplete markets. A market is said to be incomplete if the given traded assets are insufficient to hedge a contingent claim. This situation occurs, for example, when the underlying stock process follows jump-diffusion processes. Due to the jump part, it is impossible to construct a hedging portfolio with stocks and riskless assets. Contrary to the case of a complete market in which only one equivalent martingale measure exists, there are infinite numbers of equivalent martingale measures in an incomplete market. Our research here is focusing on risk minimizing hedging strategy and its associated minimal martingale measure under the jump-diffusion processes. Based on this risk minimizing hedging strategy, we characterize the dynamics of a risky asset and derive the valuation formula for an option price. The main contribution of this paper is to obtain an analytical formula for a European option price under the jump-diffusion processes using the minimal martingale measure.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.5 no.3
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• pp.164-168
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• 2012

LDPC decoder architectures are generally classified into serial, parallel and partially parallel architectures. Conventional method of LDPC decoding in general give rise to a large number of computation operations, mass power consumption, and decoding delay. It is necessary to reduce the iteration numbers and computation operations without performance degradation. This paper studies Horizontal Shuffle Scheduling (HSS) algorithm. In the result, number of iteration is half than conventional algorithm without performance degradation. Finally, this paper present design methodology of high-speed LDPC decoder and confirmed its throughput is up to about 600Mbps.

• Proceedings of the Korean Operations and Management Science Society Conference
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• 2000.04a
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• pp.253-256
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• 2000

In general, Automated Storage/Retrieval Systems (AS/RS ) have racks of equal sized cells to utilize the concept of unit-load. Most of the techniques for the performance estimation of a unit-load AS/RS are a static model or computer simulation. Especially, their models were developed under assumption that the Storage/Retrieval (S/R) machine performs only single command (SC) or dual command (DC). In reality, defending on the operating policy and the status of the system at a particular time, the S/B machine performs a SC or a DC, or becomes .: idle. In order to resolve these weak points, we propose a stochastic model for the performance estimation of unit-load AS/RS by using a single-server queueing model. Expected numbers of waiting storage and retrieval commands are found

• Journal of the military operations research society of Korea
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• v.18 no.2
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• pp.66-95
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• 1992

Shortest paths are one of the simplest and most widely used concepts in deterministic networks. A decison of troops movement route can be analyzed in the network with a shortest path algorithm. But in reality, the value of arcs can not be determined in the network by crisp numbers due to imprecision or fuzziness in parameters. To account for this reason, a fuzzy network should be considered. A fuzzy shortest path can be modeled by general fuzzy mathematical programming and solved by fuzzy dynamic programming. It can be formulated by the fuzzy network with lingustic variables and solved by the Klein algorithm. This paper focuses on a revised fuzzy shortest path algorithm and an application is discussed.

• Proceedings of the Korean Operations and Management Science Society Conference
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• 2002.05a
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• pp.152-157
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• 2002

본 연구에서는 컨테이너 터미널의 자동화 설비 중 안벽용 크레인(Quay Crane: QC)과 장치장용 크레인(Automated Transfer Crance: ATC)간의 컨테이너 이송을 담당하는 AGV(Automated Guided Vehicle)의 운영에 관한 시뮬레이션을 수행할 수 있는 전용의 시 뮬레이터를 개발하는데 목적은 두고 수행하였다. 자동화 컨테이너 터미널의 처리 능력은 선석의 QC 능력에 의해서 결정되지만, QC의 능력을 최적화하기 위해서는 컨테이너 터미널 내에서의 AGV의 운영 효율이 결정적인 역할을 한다. 또한 AGV의 운영 효율에는 장치장의 ATC 작업시간이 영향을 준다. 연구결과, AGV의 운영 효율 평가를 위한 시뮬레이터를 개발하였으며, 이를 이용하여 QC의 작업시간과 ATC의 작업시간에 따른 AGV의 적정대수를 산출하였다. 본 시뮬레이터는 실제 컨테이너 터미널의 운영 상대와 유사한 시뮬레이션을 수행할 수 있고, 컨데이니 터미널의 운영 능력을 산출하는데 적합하도록 개발되었다.

• Journal of the Korean Operations Research and Management Science Society
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• v.16 no.1
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• pp.89-96
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• 1991

When a feasible solution approaches to the optimal extreme point in Karmakar's algorithm, components of the search direction vector for a solution converge at a certain value according to the corresponding columns of the optimal basis and the optimal nonbasis. By using this convergence properties of Karmarkar's algorithm, we can identify columns of the optimal basis before the final stage of the algorithm. The complexity of Karmarker's algorithm with newly proposed termination criterion does not increase. A numerical experiments for the problems which were generated by random numbers are also illustrated. Experimental results show that the number of iterations required for determining columns of the optimal basis depends on problems. For all cases, however, columns of the optimal basis are exactly verified when this termination criterion is used.