• Nuclear Engineering and Technology
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• v.53 no.7
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• pp.2104-2125
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• 2021

This paper presents the verification and validation (V&V) of a calculation module for isotope inventory prediction to control the back-end cycle of spent nuclear fuel (SNF). The calculation method presented herein was implemented in a two-step code system of a lattice code STREAM and a nodal diffusion code RAST-K. STREAM generates a cross section and provides the number density information using branch/history depletion branch calculations, whereas RAST-K supplies the power history and three history indices (boron concentration, moderator temperature, and fuel temperature). As its primary feature, this method can directly consider three-dimensional core simulation conditions using history indices of the operating conditions. Therefore, this method reduces the computation time by avoiding a recalculation of the fuel depletion. The module for isotope inventory calculates the number densities using the Lagrange interpolation method and power history correction factors, which are applied to correct the effects of the decay and fission products generated at different power levels. To assess the reliability of the developed code system for back-end cycle analysis, validation study was performed with 58 measured samples of pressurized water reactor (PWR) SNF, and code-to-code comparison was conducted with STREAM-SNF, HELIOS-1.6 and SCALE 5.1. The V&V results presented that the developed code system can provide reasonable results with comparable confidence intervals. As a result, this paper successfully demonstrates that the isotope inventory prediction code system can be used for spent nuclear fuel analysis.

• Proceedings of the Korean Operations and Management Science Society Conference
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• 1998.10a
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• pp.392-395
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• 1998

This paper suggests the“infinite-retailer model”to approximate expected backorders per cycle of the One-warehouse N-retailer distribution system where the warehouse holds back some of the replenishment quantity to satisfy retailer backorders at the end of the cycle through direct shipping to customers. The main objective is to show the functional relationship between the warehouse inventory and the expected backorders per cycle. We illustrate the relationship using a uniform demand case.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.37 no.3
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• pp.129-138
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• 2014

This paper is to analyze the cycle time of the vendor in a single-vendor multi-buyers supply chain. The vendor is the manufacturer and the buyers are the retailers. The cycle time of the vendor is the elapse time from the beginning time of the production to the beginning time of the next production. The cycle time of the vendor that minimizes the total cost in a supply chain is analyzed. The cost factors are the production setup cost and the inventory holding cost of the vendor, the ordering cost and the inventory holding cost of the retailers. The cycle times of the vendor obtained with the costs of the vendor is compared with those obtained with the costs of the vendor and the retailers. Various numerical examples are tested if the cycle times of the vendor for both methods are the same.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.37 no.1
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• pp.165-171
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• 2014

We develop an optimization algorithm for a periodic review inventory system under a stochastic budget constraint. While most conventional studies on the periodic review inventory system consider a simple budget limit in terms of the inventory investment being less than a fixed budget, this study adopts more realistic assumption in that purchasing costs are paid at the time an order is arrived. Therefore, probability is employed to express the budget constraint. That is, the probability of total inventory investment to be less than budget must be greater than a certain value assuming that purchasing costs are paid at the time an order is arrived. We express the budget constraint in terms of the Lagrange multiplier and suggest a numerical method to obtain optional values of the cycle time and the safety factor to the system. We also perform the sensitivity analysis in order to investigate the dependence of important quantities on the budget constraint. We find that, as the amount of budget increases, the cycle time and the average inventory level increase, whereas the Lagrange multiplier decreases. In addition, as budget increases, the safety factor increases and reaches to a certain level. In particular, we derive the condition for the maximum safety factor.

• Journal of The Korean Society of Agricultural Engineers
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• v.53 no.3
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• pp.59-64
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• 2011

The objective of the study is to develop life cycle inventory (LCI) database of dam, a major facility for irrigation water supply. The types of database developed are three out of nine dams according to the size of the wate r storage capacity: two kinds larger than 500,000 $m^3$ depending on gate for discharging (Type 1) and the other dam smaller than 500,000 $m^3$ (Type 2). According to the LCI analysis, type 1 larger than 500,000 $m^3$ storage capacity with gate has the lowest environment impact in the 6 impact categories. The impact of the type 1 accounts for 7~35 % of the type 2 for supplying irrigation water. Comparing with the environment impacts of water for other uses such as drinking and industrial water, the impacts of 1 $m^3$ irrigation water supply is 4~45 % of the one for industrial water supply and 1~16 % of the drinking water's. The three types of LCI DB on the irrigation water by dams will be useful in the application of Life Cycle Assessment in agricultural products and environmental labelling including carbon footprint since it is complied to the guidelines of LCI DB constr uction issued by Ministry of Environment and Ministry of Knowledge Economy.

• Journal of applied mathematics & informatics
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• v.4 no.2
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• pp.457-468
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• 1997

The present paper deals with an economic order quan-tity model for items deteriorating at some constant rate with demand changing at a known and at a random point of time in the fixed pro-duction cycle.

• Proceedings of the Korean Operations and Management Science Society Conference
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• 1995.04a
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• pp.476-486
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• 1995

In this paper, an attempt has been made to revise Raafat' s(1985) results on an inventory model for decaying raw materials and the finished product at a constant rate which was based on Goyal's integrated inventory model for a single product system. This paper is concerned with scheduling the frequencies of order quantity of several different raw materials on a production inventory model. The purpose of this paper is to present a simple method of deciding the frequencies of order quantity of raw materials, in the sense of minimizing the average total cost of the system. We describe on iterative procedure for directly determining near optimal frequencies of order quantity for the raw materials and the associated fundamental cycle time which can be used for constructing the production duration of the finished product. In cases where feasible schedules cannot be constructed using the values from the iterative procedure, the procedure provides a basis for changing the order quantity frequencies and the fundamental cycle time to obtain feasible schedules. An example is given to illustrate the derived results.

• The Journal of Economics, Marketing and Management
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• v.3 no.4
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• pp.13-20
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• 2015

This study examined the relationship between working capital management and performance of listed companies Stock Exchange in Tehran. A total of 40 companies from the cement industry for the period 2007 to 2010 of which only 25 were selected for this study had the condition. In order to achieve the objectives, this study surveys the exploration of correlation regression analysis and used the curve obtained, the regression equation. To test the hypothesis, quantitative analysis was used as a method. The results showed a negative relationship between the variables of working capital management and the company's performance and the only variable cash conversion cycle did not show a significant relationship. There is often a negative correlation between the variables studied. This study is based on five assumptions impact of working capital management on corporate profitability is examined. Therefore, the results suggest that the variables in working capital (average collection of receivables, average inventory turnover period, the average net debt and average transaction cycle) and net operating profit is significant negative correlation Net cash conversion cycle and only illustrates the relationship is not significant. Thus, it showed that in debt collection and debt payment period, the turnover of inventory and net trade cycle to reduce the profitability of companies will increase.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 1999.10a
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• pp.83-90
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• 1999

Centralized safety stock in a periodic replenishment system which consists of one central warehouse and m regional warehouse can reduce backorders allocation the centralized safety stocks to regional warehouse in a certain instant of each replenishment cycle. If the central warehouse can not monitoring inventories in the regional warehouse, then we have to predetermine the instant of allocation according to demand distribution and this instant must be same for all different replenishment cycle. However, transition of inventory level in each cycle need not to be same, and therefore different instant of the allocation may results reduced shortage compare to the predetermined instant of allocation. In this research, we construct a dynamic model based on the assumption of monitoring inventories inventories in the regional warehouse everyday, and develop an algorithm minimize shortage in each replenishment cycle using dynamic programming approach.

• Korean Management Science Review
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• v.29 no.3
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• pp.107-120
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• 2012

In this paper we propose an effective genetic algorithm for solving the integrated inventory and routing problem of supply chain composed of multi-warehouses and multi-retailers. Unlike extant studies dealing with integrated inventory and routing problem of supply chain, our model incorporates more realistic aspect such as positive inventory at the multi-warehouses under the assumption of inventory policy of power of two-replenishment-cycle. The objective is to determine replenishment intervals for the retailers and warehouses as well as the vehicles routes so that the total cost of delivery and inventory cost is minimized. A notable feature of our algorithm is that the procedure for evaluating the fitness of objective function has the computational complexity closing to linear function. Computational results show effectiveness of our algorithm.