• Architectural research
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• 제11권2호
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• pp.43-49
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• 2009

Since the late 1980s, the schedule technique applied to the construction industry around the world has rapidly changed from the traditional ADM (Arrow Diagramming Method) to the PDM (Precedence Diagramming Method) technique. The main reason for this change is to overcome the limits and inconveniences of the traditional ADM technique. The time-cost trade-off is one of the core scheduling techniques to establish the best optimized combination plan in terms of a relationship between the cost and schedule. However, most of the schedule-related textbooks and research papers have discussed and proposed applications of a time-cost trade-off technique based only on the Finish to Start relationship. Therefore, there are almost no consideration and discussion of problems or restrictions that emerge when the time-cost trade-off technique is applied to the PDM network that has overlapping relationships. This paper proposes the lead-time adjustment method as a methodology for overcoming some restrictions that are encountered when the time-cost trade-off technique is applied to the overlapping relationships of the PDM network.

• Structural Engineering and Mechanics
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• 제71권2호
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• pp.139-151
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• 2019

In a project schedule, it is possible to reduce the time required to complete a project by allocating extra resources for critical activities. However, accelerating a project causes additional expense. This issue is addressed by finding optimal set of time-cost alternatives and is known as the time-cost trade-off problem in the literature. The aim of this study is to identify the optimal set of time-cost alternatives using a multiobjective teaching-learning-based optimization (TLBO) algorithm integrated with the non-dominated sorting concept and is applied to successfully optimize the projects ranging from a small to medium large projects. Numerical simulations indicate that the utilized model searches and identifies optimal / near optimal trade-offs between project time and cost in construction engineering and management. Therefore, it is concluded that the developed TLBO-based multiobjective approach offers satisfactorily solutions for time-cost trade-off optimization problems.

• 한국국방경영분석학회지
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• 제6권1호
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• pp.79-92
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• 1980

In cost-only incentive contract the emphasis is the attainment of efficient and effective cost control. In contrast multiple incentives contract correlates contractor's profit motives with the generalized government objective function, the decision variables of which are performance or quality (technical progress), time or schedule (timely development and delivery) and the cost (efficient and effective cost control) Under multiple incentive structure, it is essential to formulate the trade-off curves between cost and performance, which are called iso-fee curves. Trade-off curves depict the combination of cost and performance achievement for which the contractor will be rewarded with the same fee. The basic function of trade-off curves is to show he the contractor will be motivated by incentive arragement to trade off or sacrifice the achievement in one incentive element for the acnievment in another.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2015년도 추계 학술논문 발표대회
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• pp.76-77
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• 2015

In construction industry, management of construction factors such as cost, schedule, quality and safety is the most important key for delivering successful projects. According to the Smart Market Report, a magazine specialized in construction industry, recently said 'Off-site Prefabrication' is a significant trend related with construction productivity in global construction industry. It is a kind of practice shift from On-site to Off-site. A lot of general contractors in oversea have been using 'Multi-trade MEP Ceiling Rack Prefabrication' method for getting benefits such as decreased cost & schedule and increased labor productivity. Thus, in this paper, critical management factors at each phase from design to installation was derived by researching case studies. Forwardly, it can be a basic guideline for applying Multi-trade MEP Ceiling Rack Prefabrication in Korea construction industry.

• 한국건설관리학회논문집
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• 제16권6호
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• pp.53-62
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• 2015

공기비용 트레이드오프 모델은 건설프로젝트의 계획 및 관리에 있어 매우 중요하다. TCTO 모델은 연속모델과 분절모델 두 가지 모델이 개발되어왔다. 그러나 한 종류의 모델만을 사용하여 현실적인 공기단축 시나리오를 적용하기에는 한계가 있다. 이에 TCTO 의 연속적인 모델과, 분절모델을 결합하여 진보된 모델을 제시하였으며 또한, 비선형 관계, 인센티브 및 지체보상금 고려가 가능하도록 TCTO모델에 포함되어 있다. 이런 특성들은 건설프로젝트에 적용가능하다. 6개의 activities로 구성된 CPM 네트워크는 연구에서 제안된 모델을 설명하기 위해 사용되었다. 제시한 모델은 모든 제약 조건을 만족시키는 최적 스케쥴 계산이 가능하다. 결과적으로 본 연구에서 제시한 진보된 TCTO모델은 기존의 모델보다 최적화된 공기단축이 가능하다.

• 한국경영과학회:학술대회논문집
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• 대한산업공학회/한국경영과학회 1996년도 춘계공동학술대회논문집; 공군사관학교, 청주; 26-27 Apr. 1996
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• pp.213-216
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• 1996

R'||'&'||'D project management is a process of decisions concerned with the achievement of goals of objectives. Especially, defense R'||'&'||'D project planning is the key in the successfull management of defense development. The defense project managers are constantly having to perform "what if\ulcorner" exercise, such as what if the project is extended out for an additional cost\ulcorner In this reserch, we developed a schedule-cost analysis model based upon Critical Path Method(CPM) and Venture Evaluation and Review Technique(VERT) for schedule-cost trade off analysis defense R'||'&'||'D projects. In the first step, a deterministic model is developed as a heuristic which deterministic model is developed as a heuristic which determines the schedule extension and reduction cost as a function desired schedule. In the second step, a stochastic network simulation model is developed to analyse the project risk (sucess and failure). The expected time and cost can be determined for desired schedule under the assumptions of stochastic arc data (time and cost) with a various precedence relationships. This model provides the defense R'||'&'||'D managers with an estimated and expected cost for curtailing or extending a project a given amount of time. The effectiveness and efficiency of the proposed methods, a heuristic and stochastic networks simulations, have been demonstrated through examples.

• Journal of Construction Engineering and Project Management
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• 제4권3호
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• pp.53-59
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• 2014

Project managers are responsible to conduct project on time with least amount of costs and the most possible quality with respect to shortage of resources and environmental certainties. They have to make the best decision to reach such conflicting objects. In this study the project scheduling with multi goals-multi modes was planned in fuzzy conditions under resource constraints and expanded by fuzzy goal programing (FGP). The project cost was calculated by the price of renewable resources and the quality criteria were evaluated by the quality function deployment method (QFD). Finally the model was verified by a construction case study with 22 activities along with solving by GAMS. The results showed that this model could provide a systematic framework to facilitate the decision making process and made the project managers to be able to schedule the project closer to reality.

• 한국인터넷방송통신학회논문지
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• 제13권4호
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• pp.99-106
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• 2013

일반적으로 소프트웨어를 개발하는데 소요되는 일정 단축은 추정된 명목상 일정을 기준으로 75% 범위 내에서 결정된다. 그러나 지금까지 명목상 개발 일정이 명확히 제시되지 않아 개발일정 단축 가능성을 판단하는데 어려움이 있다. 따라서 본 논문은 다양하게 제안된 명목상 개발일정 기준을 고찰하여 최적의 범위를 결정하였다. ISBSG Release 8의 기능점수 기반 실제 수행된 1,595개 프로젝트를 대상으로 이 기준 범위에 속하는 614개의 프로젝트를 추출하였다. 이 데이터들을 대상으로 개발노력 추정 모델을 유도하였다. 또한, 추정된 개발노력 모델에 기반하여 개발기간을 추정하는 모델을 유도하였다. 제안된 모델을 적용시 실제 프로젝트를 개발시 요구되는 개발노력과 개발기간을 보다 현실적으로 추정할 수 있을 것이다.

• 한국경영과학회:학술대회논문집
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• 한국경영과학회 2000년도 추계학술대회 및 정기총회
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• pp.268-271
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• 2000

In these days, the technical advances and complexities have generated much of the difficulties in managing the project resources, both time and costing to accomplish the project in the most efficient manner. The project manager is frequently required to render judgements concerning the schedule and resource adjustments. This research develops an analytical model for a schedule-cost and risk analysis based on visual PERT/CPM. We used a two-step approaches ：in the step 1, a deterministic PERT/CPM model for the critical path and estimating the project time schedule and related resource planning, In the second step, we developed a heuristic model for crash and stretch out analysis based upon a time-cost trade-off associated with the crash and stretch out of the project. Computer implementation of this model is provided based on GUI-Type objective-oriented programming for the users and provided displays of all the inputs and outputs in the form of visual graphical. Also developed GUI-type program, Dongeui Visual-PERT/CPM. The results of this research will provide the project managers with an efficient management tool.

• 품질경영학회지
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• 제50권2호
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• pp.265-286
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• 2022

Purpose: The time and cost of a project activity exists in a selected mode and there is a quality level for the selected mode, and the time and cost of the current activity is determined by the quality level of the preceding activity. When an activity is a predecessor activity of an activity, it is characterized as a trade-off problem in which the time and cost of the activity are determined according to the quality level of the activity. Methods: A neighbor search heuristic algorithm obtains a solution by (1) randomly determining the mode, quality level, and assignment order for each activity. (2) get a solution by improving the solution by changing the possible modes and quality levels; (3) to find a solution by improving the solution from the point where it is feasible to advance the start time. Here, Case[1] is a method to find the optimal solution value after repeating (1). Case [2] is a method for finding a solution including (1) and (2). Case [3] refers to a method for finding solutions including (1), (2), and (3). Results: It can be seen that the value of the objective function presented by the algorithm changes depending on how the model of the heuristic algorithm is designed and applied. In other words, it suggests the importance of algorithm design and proves the importance of the quality problem of activities in the project schedule. Conclusion: A study significance of the optimization algorithm and the heuristic algorithm was applied to the effect of the quality of the preceding activity on the duration and cost of itself and the succeeding activity, which was not addressed in the project schedule problem.