• 한국통신학회논문지
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• 제31권5A호
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• pp.493-500
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• 2006

논문은 OFDMA/TDD 시스템에서 하향링크 빔 형성 송신기의 효율적인 구조와 설계 변수의 최적화에 대하여 고찰하였다. 다수의 송신 안테나를 사용하는 하향링크 빔 형성 송신기 설계에 있어 다수의 사용자에 대한 효율적인 빔 형성 구조 설계와 송신기 블록의 word-length 는 송신기의 성능과 하드웨어 복잡도 측면에서 중요한 설계 변수가 된다. 본 논문에서는 기지국 수신에서 사용자 구분 없이 부반송파별 가중치만 메모리에 저장하고, IFFT 입력의 부반송파 단위에서 사용자에 따라 할당된 부반송파의 가중치를 고속으로 계산하여 적용하는 효율적인 빔형성기 구조를 제시하였다. 또한, 고정 소수점 시뮬레이션을 통하여 최적의 설계 변수를 분석하였다. 제시한 구조는 프레임 당 최대 사용자 수에 비례하게 메모리를 줄일 수 있으며, 또한 기지국 수신에서 사용자 제어 없이 FFT 출력을 바로 송신에 적용하여 OFDM 한 심볼의 처리 시간을 줄일 수 있고 송신기에서 빔 형성 계산은 별도의 처리 시간을 요구하지 않는 장점이 있다.

• 대한산업공학회지
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• 제37권4호
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• pp.358-366
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• 2011

Multi-criteria ABC inventory classification, which aims to classify inventory items by considering more than one criterion, is one of the most widely employed techniques for inventory control. The weighted linear optimization (WLO) model proposed by Ramanathan (2006) solves the problem of multi-criteria ABC inventory classification by generating a set of criterion weights for each inventory item and assigning a normalized score to the item for ABC analysis. However, the WLO model has some limitations. First, many inventory items can share the same optimal score, which can hinder a precise classification of inventory items. Second, the model allows too much flexibility in weighting multiple criteria; each item is allowed to choose its own weights so that it can maximize its score. As a result, if an item dominates the others in terms of a certain criterion, it may be classified into a higher class regardless of other criteria by assigning an overwhelming weight to the criterion. Consequently, an item with a high value in an unimportant criterion and low values in others may be inappropriately classified as class A, leading to an inaccurate classification of inventory items. To overcome these shortcomings, we extend the WLO model by using the cross-efficiency method in data envelopment analysis. We claim that the proposed model can provide a more reasonable and accurate classification of inventory items by mitigating the adverse effect of flexibility in the choice of weights and yielding a unique ordering of inventory items.

• 미생물학회지
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• 제23권4호
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• pp.282-290
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• 1985

Small size antibiotic resistance plasmids having molecular weights less than 10 Mdal were isolated and characterized from ten clinically isolated multiple resistant Staphylococcus aureus. Agarose gel electrophoresis profiles and antibiotic resistance patterns divided these strains into four groups. Strain 2-23-6, the representative strain of a group of five strains conferred two plasmids of molecular weights $1.6{\times}10^6\;dal\;and\;2.0{\times}10^6$ dal. The small plasmid (pSBK 112) specified macrolides, lincosamides and streptogramin type B (MLS) resistance gene which are expressed constitutively. Lage plasmid (pSBK 125) specified chloramphenicol resistance gene which is inducible. Strain 10-5 conferred a $3.0{\times}10^6$ dal plasmid (pSBK 141) which carry an inducible ampicillin resistance gene and strain P-H-2 conferred and $1.6{\times}10^6$ dal plasmid (pSBK 190) which carry a constitutive MLS resistance gene. Strain D-H-1 conferred four plasmids of molecular weights $0.8{\times}10^6$ dal (pSBK 201), $1.6{\times}10^6$ dal (pSBK 202), $2.5{\times}10^6$ dal (pSBK 203), and $1.2{\times}10^7$ dal (pDBK 204), respectively. Among those four plasmids, only pSBK 203 specified chloramphenicol resistance gene. Curing of constitutive MLS resistance using acriding orange or ethidium bromide in 2-23-6 and P-H-2 strains produced 'inducible' MLS resistance strains which are less resistant to MLS than the wild type strains, suggesting that there are two resistance genes in both strains; one is constitutive and the other is inducible.

• 지능정보연구
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• 제6권1호
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• pp.97-112
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• 2000

The basic idea of case-based reasoning is to solve a new problem using the previous problem-solving experiences. In this research we develop a case-based reasoning system for equipment malfunction diagnosis. We first divide the case base into clusters using the case-based clustering technique. Then we develop an appropriate case-based diagnostic system for each cluster. In other words for individual cluster a different case-based diagnostic system which uses different weights for attributes is developed. As a result multiple case-based reasoning system are operating to solve a diagnostic problem. In comparison to the performance of the single case-based reasoning system our system reduces the computation time by 50% and increases the accuracy by 5% point.

• Management Science and Financial Engineering
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• 제13권2호
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• pp.1-27
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• 2007

This paper presents a fuzzy-goal programming(FGP) approach for Bi-Level Linear Multiple Objective Decision Making(BLL-MODM) problem in a large hierarchical decision making and planning organization. The proposed approach combines the attractive features of both fuzzy set theory and goal programming(GP) for MODM problem. The GP problem has been developed by fixing the weights and aspiration levels for generating pareto-optimal(satisfactory) solution at each level for BLL-MODM problem. The higher level decision maker(HLDM) provides the preferred values of decision vector under his control and bounds of his objective function to direct the lower level decision maker(LLDM) to search for his solution in the right direction. Illustrative numerical example is provided to demonstrate the proposed approach.

• 한국국방경영분석학회지
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• 제17권1호
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• pp.84-104
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• 1991

Up to the present, the evaluation measures in the production and inventory management have been studied under the pre-condition that the costs for major factors(e.g,. cost of carrying inventory, cost of demand shortage) are given easily, although in practice, it is difficult. The case in which multiple participants have a different viewpoints in production and inventory management has not been studied, in spite of its frequent occurrence. This study suggests a production and inventory model with multiple objectives corresponding to major factors and the related interactive algorithm based on the preference structures of participants. The problem can be solved through a weighting vector generated by an interaction with participants. The concept of equity is also used in order to guarantee the reasonable distribution of group utility in determining the individual relative weights of participants. This study includes the reality of the model and the decision process in the production and inventory management.

• Journal of the korean society of oceanography
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• 제34권3호
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• pp.179-183
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• 1999

A light-weight multiple piston corer to meet increasing coring needs in areas where R/V access is limited, is designed and discussed. Hydraulically-damped and spring-driven piston system not only virtually undisturbed surface sediments but also facilitate the recovery and subsequent operation including pore water extraction and core slicing on board the ship. It is designed as compact, light-weight and easy to dissemble that whole gear can be carried by small passenger vehicle yet it permits thick-walled core tube for thermal insulation or large opening core tubes. Because single spring instead of heavy weights of conventional gravity-driven multiple corers is used, this device is very simple and cheap to construct.

• 산업경영시스템학회지
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• 제23권55호
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• pp.1-11
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• 2000

Taguchi's robust design methodology has focus only a single characteristic or response, but the quality of most products is seldom defined by a characteristics, and is rather the composite of a family of characteristics which are often interrelated and nearly always measured in a variety of units. The multiple characteristics problem is how to compromise the conflicts among the selected levels of the design parameters for each individual characteristic. In this paper, Methodology using SN ratio optimized by univariate technique is proposed and a parameter design procedure to achieve the optimal compromise among several different response variables is developed. Also, We propose a decision model to incorporates the values assigned by a group of experts on different factors in weighting decision. Using this model, SN ratio of taguchi method for each of subjective factors as well as values of weights are used in this comprehensive method for weighting decision.

• 전자공학회논문지B
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• 제33B권3호
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• pp.142-150
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• 1996

Monopulse technique has been widely used for a bearing estimation of a desired signal. This method can estimate the bearing of the signal with only one pulse, so computational load and complexity are low and its processes are simple. But if the desired signal incidents with interferences or multiple signals exist in the beams, the method fails to estimate correct signal angle. To solve this problem, the method to use adaptive array was proposed. In conventional adaptive array methods, sum beam was formed with fixed weights and ifference beam was formed with adaptive weights determined to minimize beamformer output power with one or more linear constraints, or an algorithm to minimize each sum beam and difference beams simultaneously using adaptively formed one basic beam. Theroretical analyses and simulation results show that the performance of the proposed method is superior to that of conventional algorithms.

• ETRI Journal
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• 제31권3호
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• pp.263-270
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• 2009

This paper investigates linear soft combination schemes for cooperative spectrum sensing in cognitive radio networks. We propose two weight-setting strategies under different basic optimality criteria to improve the overall sensing performance in the network. The corresponding optimal weights are derived, which are determined by the noise power levels and the received primary user signal energies of multiple cooperative secondary users in the network. However, to obtain the instantaneous measurement of these noise power levels and primary user signal energies with high accuracy is extremely challenging. It can even be infeasible in practical implementations under a low signal-to-noise ratio regime. We therefore propose reference data matrices to scavenge the indispensable information of primary user signal energies and noise power levels for setting the proposed combining weights adaptively by keeping records of the most recent spectrum observations. Analyses and simulation results demonstrate that the proposed linear soft combination schemes outperform the conventional maximal ratio combination and equal gain combination schemes and yield significant performance improvements in spectrum sensing.