• 품질경영학회지
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• 제31권3호
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• pp.185-192
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• 2003

In this paper, the properties on the optimal replacement policies for the general failure model are developed. In the general failure model, two types of system failures may occur : one is Type I failure (minor failure) which can be removed by a minimal repair and the other, Type II failure (catastrophic failure) which can be removed only by complete repair. It is assumed that, when the unit fails, Type I failure occurs with probability 1-p and Type II failure occurs with probability p, $0\leqp\leq1$. Under the model, the system is minimally repaired for each Type I failure, and it is repaired completely at the time of the Type II failure or at its age T, whichever occurs first. We further assume that the repair times are non-negligible. It is assumed that the minimal repair times in a renewal cycle consist of a strictly increasing geometric process. Under this model, we study the properties on the optimal replacement policy minimizing the long-run average cost per unit time.

• 상하수도학회지
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• 제22권5호
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• pp.511-516
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• 2008

Since 1989, Advanced drinking water treatment processes began to build in Korea, especially the water treatment plants around the Nak-dong river stream due to sequential pollutant accidents. Moreover, Advanced drinking water treatment processes, ozone and GAC, are again to be built in water treatment plants around Han-river stream to control taste and odor, micro pollutants. However, there are still a lot of discussion to decide the processes to apply for advanced treatment. Thus there are still need to understand clearly on the cost evaluation of each advanced treatment processes. The cost evaluation was accomplished based on the data of six water treatment plants which are currently being either operating or constructing. Exceptionally, PAC(Powdered Activated Carbon) process was evaluated with cost estimation from construction company. The capital cost per unit volume of ozone process was significantly decreased as the treatment capacity increased. The capital cost was in the order of GAC, ozone and GAC. The operation cost decreased in the order of PAC, GAC and ozone. The total cost considering present value shows that ozone process covers 84% of ozone and GAC process for $30,000m^3/d$ capacity while it covers less than 35% for over 140 thousands $m^3/d$ capacity. Comparing GAC only, and ozone/GAC process, ozone/GAC process is more cost effective for high capacity water treatment plant.

• Nuclear Engineering and Technology
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• 제38권6호
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• pp.561-574
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• 2006

This study presents the results of an economic analysis for a comparison of the single layer and double layer alternatives with respect to a HLW-repository. According to a cost analysis undertaken in the Korean case, the single layer option was the most economical alternative. The disposal unit cost was estimated to be 222 EUR/kgU. In order to estimate such a disposal cost, an estimation process was sought after the cost objects, cost drivers and economic indicators were taken into consideration. The disposal cost of spent fuel differs greatly from general product costs in the cost structure. Product costs consist of direct material costs and direct labor and manufacturing overhead costs, whereas the disposal cost is comprised of construction costs, operating costs and closure costs. In addition, the closure cost is required after a certain period of time elapses following the building of a repository.

• 한국CDE학회논문집
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• 제8권2호
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• pp.101-108
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• 2003

Presented in this paper is the development of an product cost estimation system at the product design stage. The efficient cost estimation function at the design stage is essential for the cost reduction activities through the entire product life cycle. For this purpose, it is necessary to establish a systematic working procedure, and to develop information system for managing a great deal of production and product-related data required for the cost estimation. The developed system has the capability of estimating a cost of assembly type products as well as unit-item type products. As proposed system is based on the variant approach, it can be used easily at an early design stage without the need for detail design information. Also, this system is integrated with legacy PDM (Product Data Management) and ERP (Enterprise Resource Planning) system for fast. accurate and easy product cost estimation. The estimated cost includes material cost, overhead cost as well as labor cost.

• 한국환경과학회지
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• 제30권1호
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• pp.69-76
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• 2021

The purposes of this study were to evaluate the removal characteristics of COD, Ni, and P and to derive appropriate operating conditions for the plating wastewater according to NaOCl reaction time and pH operating conditions in the BPC unit process during the plating wastewater treatment process. As a results of evaluating the removal characteristics for raw wastewater by each BPC unit process, the removal efficiencies of COD, Ni and P in BPC 1-1 unit process were 72.8%, 99.1%, and 100.0%. Therefore, the proper reaction time of NaOCl was derived as 21.1 minutes. In order to maintain the +800 mV ORP and the reaction time of 20 minutes, the temporary injection and continuous injection of NaOCl in the BPC unit process were 13.7 mL and 18.7 mL, respectively. It was found that the temporary injection method of NaOCl reduced the chemical cost by 36.5% compared to the continuous injection method. Also, Ni showed the highest removal efficiency of 97.8% at pH 10.5. On the other hand, P showed a removal efficiency of 57.4% at pH 10.0.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2010년도 추계학술대회 초록집
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• pp.151.1-151.1
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• 2010

Natural gas hydrates (NGH) provide 170 gas volumes per unit volume of the medium and are easier to make with moderate pressure and temperature (40 bar at 3 C). Once they form, their preservation temperature is 20 C at 1 bar, which is much milder than the LNG preservation. In case of using the NGH, The small and medium sized gas well has advantages for development because of NGH's these characteristics. According to the cost evaluation report of Gudmundsson in Norway and the research of MES in Japan, the gas well that uses the NGH has a cost saving effect about 10~20% compared LNG. The effect depends on distance and production. However, cost saving and efficiency of liquefaction process is increased by the development of LNG liquefaction technology. Therefore, these factors have to be reflected in economic analysis. The purpose of this research is to compare the cost of Gas Supply Chain according to the transport type, distance and gas reserves. Especially, we consider not only the cost of facility but also the total cost (production cost, transport cost, etc).

• 한국재료학회지
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• 제27권4호
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• pp.211-215
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• 2017

Reactive Ion Etching (RIE) and wet etching are employed in existing texturing processes to fabricate solar cells. Laser etching is used for particular purposes such as selective etching for grooves. However, such processes require a higher level of cost and longer processing time and those factors affect the unit cost of each process of fabricating solar cells. As a way to reduce the unit cost of this process of making solar cells, an atmospheric plasma source will be employed in this study for the texturing of crystalline silicon wafers. In this study, we produced the atmospheric plasma source and examined its basic properties. Then, using the prepared atmospheric plasma source, we performed the texturing process of crystalline silicon wafers. The results obtained from texturing processes employing the atmospheric plasma source and employing RIE were examined and compared with each other. The average reflectance of the specimens obtained from the atmospheric plasma texturing process was 7.88 %, while that of specimens obtained from the texturing process employing RIE was 8.04 %. Surface morphologies of textured wafers were examined and measured through Scanning Electron Microscopy (SEM) and similar shapes of reactive ion etched wafers were found. The Power Conversion Efficiencies (PCE) of the solar cells manufactured through each process were 16.97 % (atmospheric plasma texturing) and 16.29 % (RIE texturing).

• Journal of the Korean Data and Information Science Society
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• 제15권4호
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• pp.773-782
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• 2004

In this paper, a random shock model for a system is considered. Each shock arriving according to a Poisson process decreases the state of the system by a random amount. A repairman arriving according to another Poisson process of rate $\lambda$ repairs the system only if the state of the system is below a threshold $\alpha$. After assigning various costs to the system, we calculate the long-run average cost and show that there exist a unique value of arrival rate $\lambda$ and a unique value of threshold $\alpha$ which minimize the long-run average cost per unit time.

• 한국데이터정보과학회:학술대회논문집
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• 한국데이터정보과학회 2004년도 추계학술대회
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• pp.33-42
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• 2004

In this paper, a random shock model for a system is considered. Each shock arriving according to a Poisson process decreases the state of the system by a random amount. A repairman arriving according to another Poisson process of rate $\lambda$ repairs the system only if the state of the system is below a threshold $\alpha$. After assigning various costs to the system, we calculate the long-run average cost and show that there exist a unique value of arrival rate $\lambda$ and a unique value of threshold $\alpha$ which minimize the long-run average cost per unit time.

• 대한안전경영과학회:학술대회논문집
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• 대한안전경영과학회 2004년도 춘계학술대회
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• pp.303-307
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• 2004

Is not used by consistency transport at transport of freight nothing but is using Pallet only by pedestal when work palletized unit load or materials handling when keep simplicity receptacle which fill raw material or product in factory in our country. Therefore, pallet that is most important function of Pallet is not empled circulation to end consumer from manufacturing plant which is circulation process whole path being done and factory. It is real condition stopping only in extremely determinate part process use of warehouse back. Additionally, it is possible to figure out the flow of all the materials loaded on the RFID pallet; product, material, raw material immediately, so that epoch-making management is possible and it contributes to the reduction of logistics cost because there are little loss or outflow of pallet. The materials flow is getting speedy and inventory is decreasing in the logistics process, and also bad inventory and loss problems are prevented. As a result, not only logistics cost of company but also national logistics cost is decreased. Thus it contributes to the strength of national competitiveness.