• 한국경영과학회지
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• 제15권1호
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• pp.63-72
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• 1990

This problem in this paper concerns the determination of safety stock for multi-echelon invenetory system. In this model the criterion is to minimize system safety stock subject to a service level constraint and expected annual total cost. Then, safety stock is determined by minimizing expected annual total cost and satisfying given service level. This expected annual total cost is obtained by expected total inventory holding cost plus the expected total stockout cost. Numerical example is given in a three-echelon inventory system. The results obtained by the use of the Hill Algorithm.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2020년도 가을 학술논문 발표대회
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• pp.179-180
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• 2020

In the budgeting guidelines, there are rules for calculating design fee and direct costs. However, only the design fee is calculated excluding the direct cost, which causes the cost to be insufficient. Therefore, this study is designed to analyze representative cases where direct costs are insufficient, draw out problems, and propose a way to improve design fees.

• 청정기술
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• 제28권2호
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• pp.182-192
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• 2022

This study provides an overview of the production costs of methane and hydrogen via water electrolysis-based hydrogen production followed by a methanation based methane production technology utilizing CO₂ from external sources. The study shows a comparative way for economic optimization of green methane generation using excess free electricity from renewable sources. The study initially developed the overall process on the Aspen Plus simulation tool. Aspen Plus estimated the capital expenditure for most of the equipment except for the methanation reactor and electrolyzer. The capital expenditure, the operating expenditure and the feed cost were used in a discounted cash flow based economic model for the methane production cost estimation. The study compared different reactor configurations as well. The same model was also used for a hydrogen production cost estimation. The optimized economic model estimated a methane production cost of $11.22/mcf when the plant is operating for 4000 hr/year and electricity is available for zero cost. Furthermore, a hydrogen production cost of $2.45/GJ was obtained. A sensitivity analysis was performed for the methane production cost as the electrolyzer cost varies across different electrolyzer types. A sensitivity study was also performed for the changing electricity cost, the number of operation hours per year and the plant capacity. The estimated levelized cost of methane (LCOM) in this study was less than or comparable with the existing studies available in the literature.

• Journal of Electrical Engineering and Technology
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• 제10권5호
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• pp.2155-2161
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• 2015

This study suggests an optical method to measure cardinal of gait (step width, step length, and stride length) with position sensitive detector (PSD). The effect of reflector’s shape (flat and cylinder) on the PSD output voltage was examined for the application of the suggested system to real situations with a curved shape reflector (e.g. shoes). Various mathematical models were evaluated to find the optimal equation for the distance measurement. Considering the effect of shape on detected signal, the inverse polynomial model was developed. The suggested method is simple to operate, low in cost, small in size, and can evaluate gait parameters in real time. This method is expected to be useful in the field of rehabilitation and sport science

• 대한안전경영과학회지
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• 제15권4호
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• pp.253-260
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• 2013

The importance of environmental protection has been increased recently. Thus the environmental management was settled in an important global competition factor. In the meantime logistics cost occupied the 8.03% of sales at 2011. This portion was greater than the portion of other countries and it was needed the reduction of logistics cost to secure the competition power. As thus in this paper we prepared the process which diminish the environmental discharge and decrease the logistics cost. We proposed the process to apply the MFCA to SCM, until now the MFCA had been used generally in manufacturing process. We defined the loss in SCM and the plus logistic, minus logistic, logistic center and the classification of cost to adopt the MFCA to SCM.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제14권1호
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• pp.40-52
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• 2020

In this paper, we consider a precoder design problem for multiuser interference channel. Most of the conventional schemes for precoder design utilize a signal-to-interference-plus-noise ratio (SINR) as a cost function. However, since the SINR metric of a desired transmitter-receiver pair is a function of precoding vectors of all transmitters in the multiuser interference channel, an analytic closed-form solution is not available for the precoding vector of a desired transmitter that maximizes the SINR metric. To eliminate coupling between the precoding vectors of all transmitters and to find a closed-form solution for the precoding vector of the desired transmitter, we use a signal-to-leakage-plus-noise ratio (SLNR) instead as a cost function because the SLNR at a transmitter is a function of the precoding vector of the desired transmitter only. In addition, channel estimation errors for undesired links are considered when designing the precoding vector because they are inevitable in a multiuser interference channel. In this case, we propose a design scheme for the precoding vector that is robust to the channel estimation error. In the proposed scheme, the precoding vector is designed to maximize the worst-case SLNR. Through computer simulation, we show that the proposed scheme has better performance than the conventional scheme in terms of SLNR, SINR, and sum rate of all users.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2020년도 봄 학술논문 발표대회
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• pp.165-166
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• 2020

The standard for the cost calculation in the field of domestic construction engineering can be largely divided into the construction cost ratio method and the actual cost addition method. However, the standard for calculating the cost of the construction cost ratio method is a trend to switch to the actual cost addition method due to limitations such as not reflecting the characteristics of the construction. Therefore, this study aims to derive implications by investigating and analyzing examples of cost standards in the field of overseas construction engineering, such as the United States, and deriving directions for improvement in domestic cost standards in the future.

• Journal of the Optical Society of Korea
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• 제20권1호
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• pp.22-28
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• 2016

The monitoring and measurement of the motion of a human joint is very important in screening for degenerative brain diseases and tracking the rehabilitation process. Since there are various medical fields to benefit from angular motion measurement, the necessity for monitoring of human joint movement is increasing. In this study, the optical sensor is composed of a light emission unit with a red LED and an optical fiber, and a reception unit with an arrangement of three photodiodes. The angular detection range was widened with the use of multiple photodiodes and the developed algorithm. The result will be useful for designing an effective angular sensor with low cost and small size.

• 한국태양에너지학회:학술대회논문집
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• 한국태양에너지학회 2011년도 추계학술발표대회 논문집
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• pp.348-353
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• 2011

Recently the renewable energy has been used widely and the importance of renewable sources is bigger than before. So the government enforced a law to the public buildings to install the renewable energy facilities. The capacity of facilities is 5% of total construction cost until April 13, 2011. Since then, the government changed the law from 5% of total construction cost to 10% of predicted energy usage because of the practical use of the renewable energy facilities. So, in this study, the comparative analysis is conducted according to the law to the building installed PV system through the EnergyPlus simulation.

• 농업생명과학연구
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• 제53권2호
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• pp.15-26
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• 2019

In vivo 측정법은 비용이 많이 들고 연구기간이 길며 동물복지 측면에서 여러 문제점이 있다. 이에 대한 대안으로 지난 수십년간 in vitro 소화율 측정법이 개발되어 왔다. 본 총설에서는 대표적인 단위 동물로써 사양되고 있는 돼지의 소화기관 특징 및 소화작용에 대한 논하였다. 또한, 최근에 개발된 daisy II incubator 를 이용한 in vitro 방법을 통해 돼지에서 주요 곡류사료로 이용되고 있는 옥수수, 쌀, 소맥 및 대맥의 회장 및 전분 건물소화율을 측정하였다.