• 환경위생공학
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• 제14권4호
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• pp.110-116
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• 1999

This study was conducted to investigate the contaminants removal efficiency and the optimal operating parameters by the internal recycle rate (IRR) in the combining A2/O process with fixed film. The average removal efficiency of BOD and COD was 92.5%~94.6%, 73.9%~87.0% in RUN 1 and 91.9%~94.7%, 77.7%~89.0% in RUN 2, respectively. Organic removal efficiency, at two different hydraulic retention time of 10 and 14hr, was similar. At 50% of the internal recycle rate, organic removal efficiency was somewhat higher than the other. Total nitrogen (T-N) and total phosphorus (T-P) were removed, highly, at 50% of internal recycle rate. It could be suggested by this study that the optimum internal recycle rate is 50% and hydraulic retention time is 14hr.

• 대한산업공학회지
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• 제19권1호
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• pp.61-71
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• 1993

We focus on a way of combining the Monte Calro methods of antithetic variates and control variates to reduce the variance of the estimator of the mean response in a simulation experiment. Combined Method applies antithetic variates (partially) for driving approiate stochastic model components to reduce the vaiance of estimator and utilizes the correlations between the response and control variates. We obtain the variance of the estimator for the response analytically and compare Combined Method with control variates method. We explore the efficiency of this method in reducing the variance of the estimator through the port operations model. Combined Method shows a better performance in reducing the variance of estimator than methods of antithetic variates and control variates in the range from 6% to 8%. The marginal efficiency gain of this method is modest for the example considered. When the effective set of control variates is small, the marginal efficiency gain may increase. Though these results are from the limited experiments, Combined Method could profitably be applied to large-scale simulation models.

• 한국대기환경학회지
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• 제20권6호
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• pp.739-748
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• 2004

A hybrid dust-collector combining a fabric filter with centrifugal force was developed to enhance the performance of the conventional fabric filter systems and its performances were evaluated to compare to that of the existing dust collector. The pressure drop rapidly increased with increasing the elapsed time and the face velocity in two filtration systems. But the increasing ratio of a hybrid dust-collector compare to the existing dust collector was lower. This results were confirmed from the performance such as cleaning interval, residual pressure drop and dust loading rate. The overall collection efficiency of the hybrid dust-collector was more than 99.6% and this showed a improvement of 0.6～2% than that of the existing dust collector. Especially, the fractional collection efficiency at the particle size of around 1${\mu}{\textrm}{m}$ is about 4% higher than that of the existing dust collector.

• KIEE International Transaction on Electrical Machinery and Energy Conversion Systems
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• 제2B권4호
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• pp.214-218
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• 2002

In this paper, the effectiveness of three different control algorithms are thoroughly investigated via simulation and a proposed efficiency evaluation method of experimentation. Both the steady state and transient characteristics of each control algorithm along with its measured efficiency are analyzed. Finally, a novel two-mode maximum power point tracking (MPPT) control algorithm combining the constant voltage control and the incremental conduction (IncCond) methods is proposed to improve the efficiency of the 3KW PV power generation system at different insolation conditions. Experimental results show that the proposed two-mode MPPT control provides excellent performance at less than 30% insolation intensity, covering the whole insolation area without additional hardware circuitry.

• Asia pacific journal of information systems
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• 제1권1호
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• pp.117-145
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• 1991

IS changeback is regarded as an offective way to control the usage of computers and communication systems which are very much limited resources and whose costs are very high, In this paper, the problem of combining the optimal chargeback system which guarantees the efficiency with the Rawls'(1971) concept of fairness. Primary conclusion of this paper is that if the value function which represents the contributions of IS user to the firm's profit is evidit and there is no uncertainty about this contribution information, optimality can be achived without any loss of fairness using full cost allocation pricing. But if there is no significant differences among contribution of each user and there is no significant differences among users because of the managerial arbitrariness, From this point of view contingent chargeback system with which manager can find the golden middle between optimality and fairness by adjusting the 'efficiency coefficient' according to his/her organizational characterisics and environments is proposed. A heuristic of finding the appropriate efficiency coefficient is also suggested.

• 한국멀티미디어학회논문지
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• 제24권8호
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• pp.1068-1075
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• 2021

Wireless sensor network (WSN) can be usefully used in battlefields requiring rapid installation and operation by enabling surveillance and reconnaissance using small sensors in areas where any existing network infrastructure is not formed. As WSN uses battery, energy efficiency acts as a very important issue in network survivability. Layer-based routing protocols have been studied a lot in the aspect of energy efficiency. Many research selected LEACH and PEGASIS protocols as their comparison targets. This study examines the two protocols and LECEEP, a protocol designed by combining their advantages, and proposes a new protocol, A-LECEEP, which is more energy efficient than the others. The proposed protocol can increase energy efficiency compared to the existing ones by eliminating unnecessary transmissions with multiple chains configuration.

• 재활복지공학회논문지
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• 제5권1호
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• pp.35-40
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• 2011

본 논문은 2.4Ghz 대역을 사용하는 WBAN (Wireless Body Area Network) 환경에서 동일 채널을 사용하는 경우에 발생하는 간섭을 제거하기 위한 방법을 MMSE (Minimum Mean Square Error), OC (Optimal Combining), ML (Maximum Likelihood) 을 비교 분석하였으며, 또한 IEEE 802.15.6에서 정의된 시나리오 및 채널 모델에 대해서 분석하였다. 모의 실험결과 ML 알고리즘이 가장 우수한 성능을 나타내는 것을 알 수 있었다. 하지만 ML 과 OC 의 경우 간섭채널의 정보를 알아야 하기 때문에 MMSE 에 비해 복잡도가 크다는 단점이 있다. 그래서 WBAN 환경에 적용하는데 어려움이 있다. 따라서 복잡도와 성능사이에 적당한 trade-off 를 만족하는 간섭제거 알고리즘을 연구해야 할 것이다.

• 대한전자공학회논문지TC
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• 제38권1호
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• pp.20-26
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• 2001

고출력 증폭기의 선형화 방법 중 Predistorter 방식은 크기가 작고, 전력 효율이 좋아 고출력 증폭기 선형화에 많이 이용된다. 본 논문에서는 새로운 측정 방법을 이용하여 고출력 증폭기에서 발생하는 혼변조 신호와 Predistorter의 혼변조 신호가 결합하는 경우에 Predistorter의 혼변조 신호의 세기와 위상 변화에 따른 고출력 증폭기에서의 혼변조 신호 감쇠량을 실험적 방법을 통해 추정하였다. 결과적으로 동일한 혼변조 신호, 결합 조건(세기와 위상)의 Predistorter의 선형화 방법은 서로 다른 경로의 신호 결함을 하는 Feedforward 선형화 방법보다 5dB 정도의 혼변조 신호 감쇠량이 낮음을 확인하였다.

• KDI Journal of Economic Policy
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• 제26권2호
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• pp.143-178
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• 2004

엄밀한 성장요인 분석을 위해서는 취업자수 및 인적 물적 자본스톡 뿐 아니라 취업자의 평균 취업시간 및 취업시간 변화에 따른 노동능률의 변화를 동시에 고려하여야 한다. 본 연구에서는 구간별로 발표되고 있는 주당 취업시간별 취업자수 통계에 최우추정법을 적용하여 총취업자의 단위 기간당 취업시간의 분포를 추정하고, 임금통계를 이용하여 단위 기간당 취업시간 변화에 따른 노동의 능률변화패턴을 추정한 후, 이를 결합하여 1963~2003년 기간중 총취업자의 주당 취업시간과 노동능률지표를 추정하였다. 추정결과에 따르면 주당 취업시간이 40시간일 때에 노동의 능률이 최대화되며, 1963~2003년 기간중 노동능률지표의 연평균 증가율은 0.14%로 계산되었다.

• 융합경영연구
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• 제11권2호
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• pp.13-22
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• 2023

Purpose: The purpose of this study is to examine the policy implications of establishing a compact city in Seoul, analyzing whether it is an appropriate and efficient eco-friendly housing supply alternative. Research design, data, and methodology: The analysis criteria include efficiency, safety, and comfort, with efficiency encompassing economic, energy, and public transport links' efficiency. Safety and comfort are aspects of eco-friendliness, housing safety, and improvement in living environments. Results: In terms of economic efficiency, compact cities are a less expensive option than purchasing land for housing construction. To increase energy efficiency, we plan to adopt eco-friendly energy sources. Transportation efficiency is high in locations near public transport stations. To enhance safety and comfort, we intend to create large-scale parks and forests in Seoul. To ensure residential safety, measures will be taken to reduce road vibration, vehicle noise, and scattering dust. Conclusions: Selecting an appropriate location that provides convenient public transportation is essential for creating a compact city for housing in a large city. Combining a compact and smart city is necessary, and implementing smart technologies is needed to prevent dust, noise, and vibrations, which are undesirable in a residential environment.