• 한국주거학회논문집
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• 제22권6호
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• pp.51-60
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• 2011

The maintenance cost depends on various factors such as building volume, floor area, number of household and so on. The maintenance cost of the apartment housing is affected by the maintenance type, building physical factor, sociogeographic aspects. Among these, the maintenance characteristics is represented and made up by the total floor area and number of household which means main factor to provide the building scale roughly. In this paper, it aimed at modelling the estimation function of the maintenance cost with the total floor area and number of household and analyzing the elasticity of the two factors. Although items of maintenance cost are various in general cost, repair cost and so on, we classified these items into the 5 categories. 5 categories are a general cost, a facility maintenance cost, a utilization cost, insurance and sanitary cost. The estimation function used a power function and it has better goodness-offitness than any other estimation methods in statistics. A power function has a three curve types with concave and convex and linear style to the origin.

• 품질경영학회지
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• 제18권1호
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• pp.77-83
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• 1990

A model for the economic design of an pn control charts with an assignale cause is presented and the loss-cost function for control schemes using these charts is derived. By minimizing this function with respect to the three control variables, namely, the sample size, the sampling interval and acceptance number, the economically optimal control plan can be optained. The article shows what influence increasing or decreasing condition, according to changeability of the size of these factors, of expected cost can have on the economy when an attribute control chart is used.

• 품질경영학회지
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• 제51권4호
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• pp.481-496
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• 2023

Purpose: The main theme of this study is to derive a profit curve by a cubic cost function for nonlinear CVP analysis. According to the analytical approach to derive a nonlinear profit function in this study, it is possible with only the existing cost structure to calculate the profit maximization and downtime point sales unlike the classical CVP analysis. Furthermore, the profit curve by the mathematical model of this study could serve as a tool to quantify the qualitative evaluation of each stage of the industry life cycle. Methods: This study followed the mathematical approach from the cubic cost function model of microeconomics, and using real data of the Bank of Korea Results: The nonlinear profit function suggested by this study is as follows; ${\pi}(x)=-a\left(x-\frac{f}{1-v}\right)^3+(1-v)x-k$ where $a=\frac{1}{3}v\left(\frac{(1-v)}{f}\right)^2,k=f-a\left(1-\frac{f}{1-v \right)^3$ Conclusion: The process and results of this study would be able to contribute not only in practice of nonlinear CVP analysis required in the management accounting or financial management, but also in cost theory of microeconomics. Also, since the life cycle of all industries in Korea was verified to the growth or mature stage, decision makers should pay careful attention to determining life cycle stages and consider the profit curve by the average variable cost ratio over multi periods.

• Industrial Engineering and Management Systems
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• 제6권2호
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• pp.136-145
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• 2007

The selection of suppliers and the determination of order quantities to be placed with those suppliers are important decisions in a supply chain. In this research, a non-linear mixed integer programming model is presented to select suppliers and determine the order quantities. The model considers the purchasing cost which takes into account quantity discount, the cost of transportation, the fixed cost for establishing suppliers, the cost for holding inventory, and the cost of receiving poor quality parts. The capacity constraints for suppliers, quality and lead-time requirements for the parts are also taken into account in the model. Since the purchasing cost, which is a decreasing step function of order quantities, introduces discontinuities to the non-linear objective function, it is not easy to employ traditional optimization methods. Thus, a heuristic algorithm, called particle swarm optimization (PSO), is used to find the (near) optimal solution. However, PSO usually generates initial solutions randomly. To improve the PSO solution quality, a heuristic procedure is proposed to find an initial solution based on the average unit cost including transportation, purchasing, inventory, and poor quality part cost. The results show that PSO with the proposed initial solution heuristic provides better solutions than those with PSO algorithm only.

• 산업경영시스템학회지
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• 제18권34호
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• pp.9-14
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• 1995

A cost minimization model for designing AS/RS (Automated Storage/Retrieval Systtems) has been developed under the S/R (Storage/Retrieval) machine throughput rate and total storage capacity requirements. The objective function includes S/R machine cost storage rack cost, and interface conveyor cost. Since the model is a nonlinear integer programming problem which is very hard to solve with large problem size, the model is simplified using previous research results to be solved exactly and a simultion procedure is combined to verify that throughput rate requirements are satisfied.

• Journal of the Korean Data and Information Science Society
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• 제23권6호
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• pp.1195-1202
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• 2012

본 논문에서는 최소수리의 비용이 시스템의 수명시간에 의존하는 경우에 연장된 보증이 주어진 수리가 가능한 시스템에 대하여 사용자 측면에서의 총기대비용을 구하였다. 이를 위해서 연장된 보증을 정의하고 사용자 측면에서 연장된 보증이 종료된 이후의 교체모형을 가정하였다. 특히, 시스템의 교체모형에서 사용자가 연장된 보증을 선택하기 위한 기준을 제시하였으며, 시스템의 고장시간이 와이블 분포를 따를 때 수치적 예를 통하여 이를 설명하였다.

• 산업경영시스템학회지
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• 제43권3호
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• pp.95-100
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• 2020

Machines and facilities are physically or chemically degenerated by continuous usage. One of the results of this degeneration is the process mean shift. The representative type of the degeneration is wear of tool or machine. According to the increasing wear level, non-conforming products cost and quality loss cost are increasing simultaneously. Therefore a periodic preventive resetting the process is necessary. The total cost consists of three items: adjustment cost (or replacement cost), non-conforming cost due to product out of upper or lower limit specification, and quality loss cost due to difference from the process target value and the product characteristic value among the conforming products. In this case, the problem of determining the adjustment period or wear limit that minimizes the total cost is called the 'process mean shift' problem. It is assumed that both specifications are set and the wear level can be observed directly. In this study, we propose a new model integrating the quality loss cost, process variance, and production volume, which has been conducted in different fields in previous studies. In particular, for the change in production volume according to the increasing in wear level, we propose a generalized production quantity function g(w). This function can be applied to most processes and we fitted the g(w) to the model. The objective equation of this model is the total cost per unit wear, and the determining variables are the wear limit and initial process setting position that minimize the objective equation.

• 물과 미래
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• 제28권1호
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• pp.153-168
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• 1995

본 연구의 목적은 다지점 유수체계의 최소비용 설계를 위한 효율적 모형을 개발하려는 것이며,로서 제안된 IDP 모형은 수문-수리학적 모형(강우-유출모형과 유역 및 하도 공수추적모형)과 최적화모형 등 2개의 부모형을 포함하고 있다. 목적함수는 대지구입비용과 유수지 설치비용 및 펌핑 시스템의 설치비용의 합으로 구성되며, 모형의 입력자료로는 각 하도자료와 수문 매개변수 및 설계강우와 비용함수등이 제시되어야 한다. 본 모형은 다지형 하도의 유수체계를 포함하고 있는 서울의 중랑천 유역에 적용되었으며, 모형의 적용결과 여러 조건의 변화에 대해서도 합리적인 유수체계의 설계가 가능하며, 다지점 유수체계의 설계에 대한 적용이 가능함을 보여주고 있다.

• KIEAE Journal
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• 제11권3호
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• pp.63-68
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• 2011

Building deterioration would be proceeded by various causes such as physical, social, economic degradation. The deterioration would be inevitably prevented or delayed to get the decent function and performance in various building part and components. The maintenance and management are continued to provide the decent living condition for the household. The maintenance means mainly a repair, including the on-time and longterm plan. The longterm repair would be conducted by the systemic preparation in management activity and a required cost. Therefore, the annual due for the longterm repair plan is important to prepare the repair cost in a required time. In this paper, it aimed at analyzing the longterm repair cost and modelling to forecast the required cost in total area, number of household and time elapse in apartment housing. The estimation model of a repair cost is used with a power function which has a good statistics. Results of this study are shown that the sample has a longterm repair due in a $2,032won/m^2{\cdot}yr$ averagely which is higher than $912won/m^2{\cdot}yr$ in domestic. Second, the longterm repair due is proportionally correlated with the time elapse in both a total area and the number of household. Third, the estimation model for the longterm repair amount is suitable for the power function which is most in any other estimation models. Fourth, the ration of the longterm plan repair due a year to the cumulated longterm amount is about 26%.

• 한국농공학회논문집
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• 제50권6호
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• pp.61-71
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• 2008

An advanced model for assessing life cycle cost of the facility containing several subdivisions has been proposed with systems engineering approach. This model evaluates the maintenance cost in the sphere of the safety as well as in that of its functionality. The proposed approach has been shown to be more reasonable and practical than existing models. The serviceability and reasonability have been proved through evaluating life cycle cost of the reservoir which is a representative agricultural facility. In addition, the proposed method is helpful to make a maintenance strategy using the survival probability in the point of safety and functionality.