• 한국경영과학회지
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• 제35권4호
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• pp.33-53
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• 2010

When purchase prices of a raw material fluctuate over time, the total purchasing cost is mainly affected by reordering time. Existing researches focus on deciding the right time when the demand for each period is replenished at the lowest cost. However, the decision is based on expected future prices which usually turn out to include some error. This discrepancy between expected prices and actual prices deteriorates the performance of inventory models dealing with fluctuating purchase prices. In this paper, we propose a new inventory model which incorporates not only cost but also risk into making up a replenishment schedule to meet each period's demand. For each replenishment schedule, the risk is defined to be the variance of its total cost. By introducing the risk into the objective function, the variability of the total cost can be mitigated, and eventually more stable replenishment schedule will be obtained. According to experimental results from crude oil inventory management, the proposed model showed better performance over other models in respect of variability and cost.

• Structural Engineering and Mechanics
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• 제59권4호
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• pp.621-652
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• 2016

A new cable-supported bridge model consisting of suspension parts, self-anchored cable-stayed parts and earth-anchored cable-stayed parts is presented. The new bridge model can be used for suspension bridges, cable-stayed bridges, cable-stayed suspension bridges, and partially earth-anchored cable-stayed bridges by varying parameters. Based on the assumption that each structural member is in either an axial compressive or tensile state, and the stress in each member is equal to the allowable stress of the material, the material quantity for each component is calculated. By introducing the unit cost of each type of material, the estimation formula for the cost of the new bridge model is developed. Numerical examples show that the results from the estimation formula agree well with that from the real projects. The span limit of cable supported bridge depends on the span-to-height ratio and the density-to-strength ratio of cables. Finally, a parametric study is illustrated aiming at the relations between three key geometrical parameters and the cost of the bridge model. The optimization of the new bridge model indicates that the self-anchored cable-stayed part is always the dominant part with the consideration of either the lowest total cost or the lowest unit cost. It is advisable to combine all three mentioned structural parts in super long span cable supported bridges to achieve the most excellent economic performance.

• 한국건설관리학회논문집
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• 제21권2호
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• pp.30-38
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• 2020

국내 공공 건설공사 공사비 수준이 시장 상황을 합리적으로 반영하지 못하고 있는 인식이 산업 전반에 널리 펴져 있는 가운데, 총사업비 관리 프로세스 상의 과도한 공사비 조정이 공사비의 적정성 미확보에 대한 핵심 원인 중 하나로 지목되고 있다. 정부는 건설 프로젝트 총사업비 산정 및 관리 프로세스에서 삭감 위주의 정책을 펼치고 있으며, 산업계에서는 예정가격 대비 낙찰가격의 수준은 매우 낮다는 인식이 일반적이다. 본 연구에서는 총사업비 관리 프로세스를 개선하기 위한 목적으로 총사업비 산정 및 관리 프로세스에 대한 분석을 수행한다. 입·낙찰 방식별 총사업비가 단계별 조정되는 과정을 분석하고, 사업구상 단계 대비 낙찰가격의 수준에 대한 정량적 비교분석 결과를 도출한다.

• 한국산업보건학회지
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• 제25권2호
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• pp.134-145
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• 2015

Objectives: An objective of this study was to perform a risk assessment and social cost-benefit analysis for revising permissible exposure limits for seven substances: Nickel(Insoluble inorganic compounds), benzene, carbon disulfide, formaldehyde, cadmium(as compounds), trichloroethylene, touluene-2,4-diisocyanate. Materials and Methods: The research methods were divided into risk and hazard assessment and cost-benefit analysis. The risk and hazard assessment for the seven substances consists of four steps: An overview of GHS MSDS(1st), review of document of ACGIH's TLVs (2nd), comparison between international occupational exposure limits and domestic permissible exposure limits(3rd), and analysis of excess workplace and excess rate for occupational exposure limits based on previous work environment measurement data(4th). Total cost was estimated using cost of local exhaust ventilation, number of excess workplace and penalties for exceeding a permissible exposure limit. On the other hand, total benefit was calculated using the reduction rate of occupational disease, number of workplaces treating each substance and industrial accident compensation. Finally, the net benefit was calculated by subtracting total cost from total benefit. Results: All the substances investigated in this study were classified by CMR(Carcinogens, Mutagens or Reproductive toxicants) and their international occupational exposure limits were stricter than the domestic permissible exposure limits. As a result of excess rate analysis, trichloroethylene was the highest at 11%, whereas nickel was the lowest at 0.5%. The excess rates of all substances except for trichloroethylene were observed at less than 10%. Among the seven substances, the total cost was highest for trichloroethylene and lowest for carbon disulfide. The benefits for the seven substances were higher than costs estimated based on strengthening current permissible exposure limits. Thus, revising the permissible exposure limits of the seven substances was determined to be acceptable from a social perspective. Conclusions: The final revised permissible exposure limits suggested for the seven substances are as follows: $0.2mg/m^3$ for nickel, 0.5 ppm(TWA) and 2.5 ppm(STEL) for benzene, 1 ppm(TWA) for carbon disulfide, $0.01mg/m^3$(TWA) for cadmium, 10 ppm(TWA) and 25 ppm(STEL) for trichloroethylene, 0.3 ppm(TWA) for formaldehyde, and 0.005 ppm(TWA) and 0.02 ppm(STEL) for toluene diisocynate(isomers).

• Nuclear Engineering and Technology
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• 제51권2호
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• pp.631-640
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• 2019

Thorium ($^{232}Th$) is four times more abundant than uranium in nature and has become a new important source of energy in the future. This is due to the ability of thorium to undergo the bombardment of neutron to produce uranium-233 ($^{233}U$). The aim of this study is to investigate the production cost of thorium oxide ($ThO_2$) resulted from the thorium extraction process. Four main parameters were studied which include raw material and chemical cost, total capital investment, direct cost and indirect cost. These parameters were justified to obtain the final production cost for the thorium extraction process. The result showed that the raw material costs were $63,126.00 - $104,120.77 (0.5 ton), $126,252.00 - $178,241.53 (1.0 ton), and $1,262,520.00 - $1,782,415.33 (10.0 tons). The total installed equipment and total cost investment were estimated to be approximately $11,542,984.10 and $13,274,431.715 respectively. Hence, the total costs for producing 1 kg $ThO_2$ were $6829.79 - $6911.78, $3540.95 - $3592.94, and $501.18 - $553.17 for 0.5, 1.0, and 10.0 tons respectively. The result concluded that with higher mass production, the cost of 1 kg $ThO_2$ would be reduced which in this scenario, the lowest production cost was $$501.18kg^{-1}$-$$553.17kg^{-1}$ for 10.0 tons of $ThO_2$ production.

• 수산경영론집
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• 제9권2호
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• pp.59-89
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• 1978

The analyzed results of the actual state of stow net fishery based on the cost expended are as follows. According to the calculation of interests, the total cost of this fishery comes to ￦38,010,653 and in this account, the production cost comes to ￦35,477,198(93.3%), the material cost, 14,567,239(38.3%), the labour cost, 12,740,274(33.5%), the expenses, ￦8,169,685(21.5%), the commision and administration expenses, 2,533,455(6.7%). The expenses for this fishery are paid out as production costs, and the expenses for sale and administration expenses are the lowest of them, and the 93% of expenses are paid out as production costs. The ratio of cost element to 100% is as follow. The wages, 28.4%, fuel, 15.2%, repair, 11.6%, deprecation, 9.5%, fishing gear, 8.7%, ice, 6.1%, container(box for fish), 5.2% administration expenses, 5.2%, food, 3.5%, ship grar, 3.2%, public welfare, 1.7%, commision for sale, 1.5%, insurance for crew, 0.2%, taxes, 0.2%. This fishery is managed with the larger fishing boat than it was and so, it demands better crews with higher wages. In the former fishery, the search for fishing ground is very difficult with long navigation and great fuel consumption. when the weak fishing gears are used, the expenses for their repair and for their gears are greatly paid out. The unit costs of catches to each box come to ￦2.807(￦187 each kg). As the ratio of cost of sales comes to 86.7%and the ratio of interests comes to ￦5,850,812(13.3%), and so the net profit comes to 13.3% of total profits. According to above the ratio of cost of sales is shown as a universal validity, Asthe total expenses comes to 86.7% to the money on sales in the break-even point, the break-even point comes to ￦26,209,168 Accordingly for the profit control the account of production should be raised, and by the saving method of expenditure the break-even point should be brought down for the development of total profits.

• Journal of applied mathematics & informatics
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• 제41권1호
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• pp.215-228
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• 2023

The ready-made garments (RMG) have been making a crucial contribution about of 81% of total export and 12.36 % of total GDP of the country which is now the single biggest export earner for Bangladesh. The cheap production cost is the key important factor to explore this RMG sector. But these RMG sector is running on the basis of intuition based decisions. Though they are making profit it is not optimal. In this study, a deterministic model is developed to help the RMG to minimize the production cost and to maximize their profit along with optimal utilization of available resources. 10 different types of products are taken from one of the garments factories of Gazipur, Dhaka to prepare this research work. This model suggests the manufacturer on which products along with how much should be produced to meet the future demand by maintaining the lowest production cost that ultimately maximize the profit of the organization, and also helps Bangladesh to compete in the international market with 'Made in Bangladesh'. LINDO programming is used here to solve this LP model.

• 대한산업공학회지
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• 제41권5호
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• pp.511-520
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• 2015

Inventory, cost, and the level of service are three interrelated key metrics that most supply chain organizations are striving to optimize. One way to achieve this goal is to create a simulation model to conduct sensitivity analysis and optimization on several different supply chain policies that can be implemented in actual operation. In this paper, a case of Xerox global supply chain modeling and analysis to assess several "what if" scenarios for the consumable policy safety stock is presented. The simulation model, combined with analytical cost model and optimization module, is used to optimize the policy safety stock level to achieve the lowest total value chain cost. It was shown quantitatively that the policy safety stock can be reduced, but it is offset by the inbound premium transportation cost to expedite supplies in shortage, and the outbound premium transportation cost to send supplies to customers via express shipment, requiring fine balance.

• Asian-Australasian Journal of Animal Sciences
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• 제7권1호
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• pp.19-29
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• 1994

The annual income (gross margin) in 1989/90 of a sample of 274 farmers in seven milk cooperatives was analyzed in the sugar cane, cassava, and horticulture areas in East Java. On average dairying contributed 42%, crops 29% and off-farm revenue 29%. Dairy income was highest in the cassava area, where it compensated for the low crop income, and lowest in the sugar cane area. Farm area and average milk yield per day per cow correlated positively with farmer's income, whereas crop income increase significantly with farm area and with the number of cows. The level of total cost per cow had a negative impact on dairy and with the number of cows. The level of total cost per cow had a negative impact on dairy and on total income. Government officials and other professionals engaged in dairying had a significantly higher total income than those with their main occupation in dairying, cropping or working as farm labourers. Uneducated farmers obtained a significantly larger income through crops, whereas farmers with tertiary education obtained more income through off-farm work, This study suggests that more attention must be paid to the actual use of labour and the improvement of the dairy output/cost ratio.

• 한국건설관리학회논문집
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• 제11권2호
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• pp.94-105
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• 2010

최근 도시내 기반시설이 노후화된 불량지구에 거주하는 사회적 약자(저소득층, 도시빈곤층)가 도시재생과정에서 지불능력한계 등에 의하여 재정착하지 못하고 있는 문제는 사회적 이슈로 부각되고 있다. 이에 본 연구에서는 사회적 약자의 재정착을 위한 방안 중 하나로 '입찰가격 최적화 및 생산비용 절감', '공기단축을 통한 비용절감', '적정 품질 만족'을 목적으로 한 '최저통합환산가격(입찰가격+공사기간환산가격) 개념의 기술제안 기반 입찰제도'를 제시하였으며, 이는 프로젝트단위 기술제안, 공종단위 기술제안, 공기단축 기술제안을 기반으로 이루어진다. 본 연구에서 제안한 최저통합환산가격 개념의 기술제안 기반 입찰제도는 공기단축에 의한 추가적인 인력 및 장비의 투입과 품질향상 등에 의하여 직접비는 상승되나 공기단축에 의한 발주자 비용, 감리비, 원주민 보상비에 대한 이자비용, 간접비, 이자 지급비, 물가 상승비 등의 절감이 기대된다. 이와 더불어 공기단축 및 공사비 절감 관련 기술 지식의 축적은 향후 프로젝트 공사비 및 공사기간 최적화가 가능함은 물론 국가 및 기업 경쟁력 향상이 기대된다.