• 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.

• Geomechanics and Engineering
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• 제32권5호
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• pp.503-512
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• 2023

In tunneling projects, a significant part of the costs is spent on segment production. By more economically producing, the cost of tunnel construction can be greatly reduced, especially in long and large-diameter tunnels. In the present study, the effect of using the Carousel method in the improvement of the production system performance compared to the conventional Static system has been studied. To carry out the research, a quantitative comparison of cost and production time was carried out for two production methods using the available documentation. The opinions of experts have been obtained using questionnaires and qualitative comparison of cost, time and production quality was done by implementation of statistical analysis. The SPSS software and the univariate t-test were used to analyze the questionnaires. According to the results of statistical analysis with SPSS, the use of the Carousel method will reduce production time and costs along with increasing manufacturing quality. According to the documentation analysis, the Carousel method reduces the cost of production by almost 30% and leads to a reduction of the production time to approximately 40% of the Static moulds system. The Carousel method has a higher production rate, efficiency, and better performance. Research into quantifying the benefits of Carousel method in the production system performance is very limited. This comparison is based on real information from the under construction Tabriz Metro project. This article can be very helpful in choosing the best production method.

• 한국콘텐츠학회논문지
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• 제14권11호
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• pp.102-110
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• 2014

본 연구는 공연여건의 성장에 걸 맞는 투자시스템으로의 변화를 모색하는 데 있다. 특히, 제작사들이 원하는 장기공연이나 오픈런 방식으로 공연여건이 조성되고 있는 상황에서 연장공연 여부를 신속히 판단할 수 있고, 제작자와 투자자 양자가 만족할 수 있는 미국식 예산수립 방식으로의 변화모색이 필요한 시점이다. 이에 구체적으로 3가지 방안을 제시하였다. 첫째, 연장공연이나 재공연 여부를 보다 정확히 판단하기 위해서는 현재와 같이 평균비용(Average Cost)을 산출하여 평균수입과 비교하기보다는 미국과 같이 한계비용(Marginal Cost)을 산출해서 비교해야 할 것이다. 둘째, 수익배분에 대한 불합리성을 극복하기 위해서는 현재와 같이 총제작비를 투자모수로 삼기보다는 미국과 같이 총제작비에서 운영비용(Operating Cost)을 제외한 프로덕션비용(Production Cost)만을 투자모수로 삼아야한다. 셋째, 앞서 언급한 한계비용의 산출과 프로덕션비용의 산출을 위해서는 미국 지출예산(Expense Budget)의 이원화 작성법의 국내 적용이 필요하겠다.

• 경영과학
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• 제13권3호
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• pp.37-48
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• 1996

This paper presents an Economic Lot Scheduling Problem in which controllable production rates are considered. We also take into account the controllable range of production rate (i.e., maximum and minimum production rate) of each product and the mold cost which varies to the production rate. A mathematical model is developed and an iterative solution procedure is suggested. The objective of this problem is to minimize production related cost and the decision variables are common production cycle time and production rate of each product. As a case study, we adapted this model to the press machine of a company.

• 경영과학
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• 제31권3호
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• pp.13-26
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• 2014

This paper considers an integrated one-vendor multi-buyer production-inventory model where the vendor manufactures multiple products in lot at their associated finite production rates. In the model, it is allowed for each product to be shipped in lot to the buyers even before the whole product production is not completed yet. Each product lot is dispatched to the associated buyer in a number of shipments. The buyers consume their products at fixed rates. The objective is to the production and shipment schedules in the integrated system, which minimizes the total cost per unit time. The total cost consists of production setup cost, inventory holding cost and shipment cost. For the model, an iterative optimal solution procedure with shipment consolidation policy incorporated. It is then tested through numerical experiments to show how efficient and effective the shipment consolidation policy is.

• 한국경영과학회:학술대회논문집
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• 한국경영과학회 2006년도 추계학술대회
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• pp.506-512
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• 2006

In this paper, we propose a lot-sizing and scheduling problem that seeks to minimize the sum of production cost and inventory cost over a given planning horizon while considering idle state of a machine in a batch production system. For this problem, we develop an integer programming model. And, we develop an efficient 2-phase heuristic algorithm to find a high quality feasible solution within reasonable time bounds. In the first phase, we seek to minimize the production cost by assigning batches to machines. Then, in the second phase, we find a production sequence of batches that reduces the inventory cost, while considering adding or deleting idle states between batches. Computational results show that the developed heuristic algorithm finds excellent feasible solutions within reasonable time bounds. Also, we could significantly reduce the total cost consisting of production cost and inventory cost by using the developed heuristic algorithm at a real manufacturing system that produces zinc alloys.

• Asian-Australasian Journal of Animal Sciences
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• 제9권4호
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• pp.411-420
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• 1996

Asia Triple HIn this study an attempt was made to determine the cost of producing fodders at Savar Dairy Farm (SDF). For this purpose, all seasonal fodders, such as Maize, Jowar, Cowpea and Oat and all perennial fodders, such as Para and Napier were studied. The highest acreage of land was allocated to high-land Para (33.8%) and the lowest acreage (2.7%) was devoted to Cowpea. Jowar attained the highest yield (74.2 tons) per hectare and Maize attained the lowest yield (25.8 tons/h). The highest cost per hectare was attributed to Jowar (TK. 20944.18) while the lowest cost was attributed to low-land para (TK. 10349.86). The cost of production of fodder per kilogram was the highest (TK. 0.66) for Maize and the lowest for Oat (TK. 0.24). The cost of production of low-land Para was much lower than that of high land Para. The per kilogram cost of silage production was the highest (TK. 0.71) for Maize and the lowest (TK. 0.31) was for Napier. The gross return analysis further showed that the highest net margin and B:C ratio were observed for Napier followed by Low-land Para, Jowar, Oat, Cowpea, High-land Para and Maize. Therefore, those fodders whose B:C ratios and yield/ha were higher should be allocated more area of land to stimulate increased returns to SDF in the future is suggested.

• 한국수소및신에너지학회논문집
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• 제17권2호
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• pp.218-226
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• 2006

It can be obtained from hydrocarbon and water, specially production of hydrogen from natural gas is most commercial and economical process among the hydrogen production methods, and has been used widely. However, conventional hydrogen production methods are dependent on fossil fuel such as natural gas and coal, and it may be faced with problems such as exhaustion of fossil fuels, production of greenhouse gas and increase of feedstock price. Thermochemical hydrogen production by nuclear energy has potential to efficiently produce large quantities of hydrogen without producing greenhouse gases. However, nuclear hydrogen must be economical comparing with conventional hydrogen production method. Therefore, hydrogen production cost was analyzed and estimated for nuclear hydrogen as well as conventional hydrogen production such as natural gas reforming and coal gasification in various range.

• 대한산업공학회지
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• 제19권3호
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• pp.71-79
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• 1993

Dynamic production planning problems are to determine the optimal production times and production quantities of product for discrete finite periods. In previous many researches, the solutions for these problems have been developed through the algorithms using dynamic programming. The purpose of this research is to suggest the new algorithm using linear programming. This research is to determine optimal production quantities of product in each period to satisfy dynamic for discrete finite periods, minimizing the total of production cost and inventory holding cost. Cost functions are concave, and no backlogging for product is allowed. The new algorithm for capacity constrained problem is developed.

• 한국농공학회논문집
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• 제57권5호
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• pp.29-35
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• 2015

The optimal greenhouse scales for controlled tomato should be studied because the increase of oil price and labor costs following the shortage of workforce makes greenhouse cultivation hard to gain profits. The purpose of this study is to estimate optimal production scales by greenhouse types for controlled tomato. The translog cost function is estimated based on the production cost survey data. The results can be summarized as follows: First, the average production cost of controlled tomato per kg decreases as the production scale increases. Second, according to the tomatoes farm of standard farming income data of RDA, the minimum production scale is 23 ton. Third, the estimated output of single-span greenhouse considering production scale with minimum average cost is 345 ton and production cost per kg is 1,476 won. The corresponding figures of multi-span greenhouse are 415 ton and 936 won, respectively. The study results can be used as basic materials for efficient decision making of tomato farmhouses and novice farmers. Also, the study shows that multi-span greenhouse should be encouraged to be built, since it requires lower marginal cost than single greenhouse. The results of this paper will help increase the income of farmhouses and cut expenses for the coming years.