• 제목/요약/키워드: Cost Variance

검색결과 287건 처리시간 0.026초

Finding Significant Factors to Affect Cost Contingency on Construction Projects Using ANOVA Statistical Method -Focused on Transportation Construction Projects in the US-

  • Lhee, Sang Choon
    • Architectural research
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    • 제16권2호
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    • pp.75-80
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    • 2014
  • Risks, uncertainties, and associated cost overruns are critical problems for construction projects. Cost contingency is an important funding source for these unforeseen events and is included in the base estimate to help perform financially successful projects. In order to predict more accurate contingency, many empirical models using regression analysis and artificial neural network method have been proposed and showed its viability to minimize prediction errors. However, categorical factors on contingency cannot have been treated and thus considered in these empirical models since those models are able to treat only numerical factors. This paper identified potential factors on contingency in transportation construction projects and evaluated categorical factors using the one-way ANOVA statistical method. Among factors including project work type, delivery method type, contract agreement type, bid award type, letting type, and geographical location, two factors of project work type and contract agreement type were found to be statistically important on allocating cost contingency.

재고풀링효과의 시뮬레이션 연구 (A Simulation Study for the Inventory Pooling Effect)

  • 정재헌
    • 산업경영시스템학회지
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    • 제35권4호
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    • pp.211-218
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    • 2012
  • We analyzed the effect of inventory pooling on the system where multiple depot was used to replenish retailers and where inventories are kept only on the depots. Inventory pooling consists of inventory integration and inventory exchange. We used simulation for checking the cost saving effect of reducing the number of depot (Inventory Integration) for the case when inventories kept on every depots are commonly used for all retailers when certain depot have stock out for their retailer assigned to them (Inventory Exchange) with the constraint of service level. Simulation on wide range of parameter settings results show that cost saving effect from inventory integration diminishes when transportation cost between depot and retailers or stock out cost, or retailer number increases. The effect becomes stronger when the demands on retailers have bigger variance or average. Also the results show that the cost saving effect from inventory exchange becomes stronger on the same situation when inventory integration effect becomes stronger.

Randomized Response Model with Discrete Quantitative Attribute by Three-Stage Cluster Sampling

  • Lee, Gi-Sung;Hong, Ki-Hak
    • Journal of the Korean Data and Information Science Society
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    • 제14권4호
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    • pp.1067-1082
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    • 2003
  • In this paper, we propose a randomized response model with discrete quantitative attribute by three-stage cluster sampling for obtaining discrete quantitative data by using the Liu & Chow model(1976), when the population was made up of sensitive discrete quantitative clusters. We obtain the minimum variance by calculating the optimum number of fsu, ssu, tsu under the some given constant cost. And we obtain the minimum cost under the some given accuracy.

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EVALUATION OF COST-TIME RELATIONSHIPS FOR CONTRACTORS PARTICIPATING IN COST-PLUS-TIME BIDDING

  • Saeed Abdollahi Sean Pour;Hyung Seok David Jeong
    • 국제학술발표논문집
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    • The 5th International Conference on Construction Engineering and Project Management
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    • pp.479-487
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    • 2013
  • State Highway Agencies (SHAs) have started utilizing cost-plus-time bidding (A+B bidding) since Federal Highway Agency (FHWA) declared it operational on May 4, 1995. Although this technique has successfully accelerated many projects by incorporating construction time in the bidding competition, a framework to illustrate the interactions of incentive/disincentive (I/D) rates on the competitiveness of contractors participating in the bid competition is yet to be developed. In a previous research, authors indicated that for each bid competition there is an efficient cap for I/D rates which are dictated by the capabilities of contractors in project acceleration. However, the results of previous study were based on the assumption that there is a statistically significant relationship between cost and time. In this study, the entire cost-plus-time projects implemented by the Oklahoma Department of Transportation (ODOT) were investigated. Then the significance of relationship between cost and time were analyzed for each contractor utilizing Analysis of Variance (ANOVA) technique, and the price-time function of each contractor was determined by regression analysis. The results of the analysis indicate that there is a significant relationship between cost and time for the majority of contractors. However, a quadratic relationship is not always significant and for some contractors a linear price-time relationship is significant. The results of this project can be used not only by ODOT to optimize the incentive/disincentive rates but also by contractors to determine the most competitive strategies of other bid participants.

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반도체 생산 배취공정에서의 배취 크기의 결정 (Batch Sizing Heuristic for Batch Processing Workstations in Semiconductor Manufacturing)

  • 천길웅;홍유신
    • 대한산업공학회지
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    • 제22권2호
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    • pp.231-245
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    • 1996
  • Semiconductor manufacturing line includes several batch processes which are to be controlled effectively to enhance the productivity of the line. The key problem in batch processes is a dynamic batch sizing problem which determines number of lots processed simultaneously in a single botch. The batch sizing problem in semiconductor manufacturing has to consider delay of lots, setup cost of the process, machine utilization and so on. However, an optimal solution cannot be attainable due to dynamic arrival pattern of lots, and difficulties in forecasting future arrival times of lots of the process. This paper proposes an efficient batch sizing heuristic, which considers delay cost, setup cost, and effect of the forecast errors in determining the botch size dynamically. Extensive numerical experiments through simulation are carried out to investigate the effectiveness of the proposed heuristic in four key performance criteria: average delay, variance of delay, overage lot size and total cost. The results show that the proposed heuristic works effectively and efficiently.

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Bilevel-programming based failure-censored ramp-stress ALTSP for the log-logistic distribution with warranty cost

  • Srivastava, P.W.;Sharma, D.
    • International Journal of Reliability and Applications
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    • 제17권1호
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    • pp.85-105
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    • 2016
  • In this paper accelerated life testing is incorporated in quality control technique of acceptance sampling plan to induce early failures in high reliability products.Stress under accelerated condition can be applied in constant-stress, step-stress and progressive-stress or combination of such loadings. A ramp-stress results when stress is increased linearly (from zero) with time. In this paper optimum failure-censored ramp-stress accelerated life test sampling plan for log-logistic distribution has been formulated with cost considerations. The log-logistic distribution has been found appropriate for insulating materials. The optimal plans consist in finding optimum sample size, sample proportion allocated to each stress, and stress rate factor such that producer's and consumer's interests are safeguarded. Variance optimality criterion is used when expected cost per lot is not taken into consideration, and bilevel programming approach is used in cost optimization problems. The methods developed have been illustrated using some numerical examples, and sensitivity analyses carried out in the context of ramp-stress ALTSP based on variable SSP for proportion nonconforming.

열화가 Wiener process를 따르는 경우의 비용을 고려한 가속열화시험 계획 (Optimal Design of Accelerated Degradation Tests under the Constraint of Total Experimental Cost in the Case that the Degradation Characteristic Follows a Wiener Process)

  • 임헌상
    • 품질경영학회지
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    • 제40권2호
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    • pp.117-125
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    • 2012
  • For the highly reliable products, an accelerated degradation test (ADT) is a useful tool which has been employed in industry to obtain reliability-related information within an affordable amount of time and cost. In an ADT, as all other reliability tests, it is important to carefully design the ADT beforehand to obtain estimates of the quantities of interest as precisely as possible. In this paper, optimal ADTs are developed assuming that the constant-stress loading method is employed and the degradation characteristic follows a Wiener process. Under the constraint that the total cost does not exceed a pre-specified budget, the stress levels, the number of test units allocated to each stress level and the number of measurement (termination time) are determined such that the asymptotic variance of the maximum likelihood estimator of the q-th quantile of the lifetime distribution at the use condition is minimized.

은닉층 다차원공간의 Vertex를 이용한 MLP의 은닉 노드 축소방법 (Reducing the Number of Hidden Nodes in MLP using the Vertex of Hidden Layer's Hypercube)

  • 곽영태;이영직;권오석
    • 한국통신학회논문지
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    • 제24권9B호
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    • pp.1775-1784
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    • 1999
  • 본 논문은 학습하는 동안 은닉 노드의 출력에 대한 분산과 평균을 평가하는 새로운 cost function을 이용하여 불필요한 은닉 노드를 축소하는 방법을 제안한다. 제안한 cost function은 필요한 은닉 노드를 활성화시키고 불필요한 은닉 노드를 상수화 시켜 제거한다. 필기체 숫자인식을 통한 실험에서 제안한 방법은 높은 인식률과 단축된 학습 시간을 나타내며 은닉 노드의 수를 37.2%까지 축소할 수 있었다.

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보전비용 증가와 생산량 감소를 고려한 공정평균이동 모형 (A Process Mean Shift Model Considering The Increasing Maintenance Cost and The Decreasing Production Volume)

  • 이도경
    • 융합정보논문지
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    • 제11권3호
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    • pp.125-131
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    • 2021
  • 모든 장비는 지속적인 사용에 의해 공정의 생산성과 경제성은 감소한다. 그러므로 일정 시점에서는 공정평균이동 문제라는 설비에 대한 예방보전이 필요하다. 설비의 보전시기를 결정함에 있어, 우리는 기존 연구에서 부분적으로 진행되어 온 보전모형들을 확장하고 통합함으로써 다양한 상황이 발생하는 생산 현장을 반영한 보전모형을 제시하고자 한다. 이를 구현하기 위해 제품규격은 상하한의 양쪽을 설정했으며, 적합품에 대해 품질손실함수를 도입했다. 마모수준에 대한 공정분산은 상수가 아닌 함수로 설정했으며, 특히 제품생산량과 보전비용에 있어서는 마모수준에 대한 함수를 개발하여 적용했다. 이로써 본 연구는 현장의 다양한 공정에 대부분 적용할 수 있는 보전모형이 될 것으로 생각한다. 추후 연구에서는 보전모형을 구성하는 부적합비용, 품질손실비용, 보전비용에 더하여 제품판매로 인한 수익 항목을 추가한 전체 수익 최대화 문제로 전개할 수 있을 것이며, 크게는 본 연구의 모형에 고장률을 도입한 보전모형으로의 확장도 생각해 볼 수 있을 것이다.

앤더슨-뉴만 모형을 이용한 여성의 직접구강진료비 지출에 관한 연구 (FACTORS AFFECTING WOMEN'S OUT-OF-POCKET COST : AN APPLICATION OF THE ANDERSEN-NEWMAN MODEL)

  • 이흥수;유형근
    • Journal of Periodontal and Implant Science
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    • 제26권3호
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    • pp.689-699
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    • 1996
  • The purpose of this research is to determine elements affecting the out-of-pocket cost of woman. The sample consisted of 1907 women living Iksan city. The survey was conducted by means of questionnaires. The model used in the analysis of out-of-pocket cost was the Andersen-Newman model, while the analysis techniques used were stepwise multiple regression and path analysis. The number of independent variables used in the analysis was 28 in total, ie 19 predisposing components, 6 enabling components, and 3 need components. In this study, the amount of variance by the model was 17 percent. Number of restricted activity days caused by oral disease, perceived susceptibility of dental disease, having a regular dental care, dental treatment costs, education level and income were found to have significant major effects on out-of-pocket cost. Number of restricted activity days caused by oral disease was the most important variable affecting out-of-pocket cost of woman. Also out-of-pocket cost shows larger effect due to enabling components than frequency of dental utilization.

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