• Korean Journal of Construction Engineering and Management
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• v.6 no.6 s.28
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• pp.171-180
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• 2005

Public rental housing is constructed, owned, and managed by the public sector. The public institution for the public rental housing controls the whole building life cycle from the construction to the demolition. The construction company for the house built for sale is strongly interested in the cost for the initial investment, while the public institution is more focused on the maintenance cost for the preservation of the buildings Nevertheless, the maintenance cost of the public rental housing has been only managed as the accounting factor without the systemic research and analysis on the actual condition. This paper shows how expenses are related to the degree of obsolescence and presents the differences of the maintenance costs by the housing area and expenditure trends (vs time) of the maintenance costs, through analyzing time series data of public rental housing maintenance cost. Further, this paper helps understanding the causes of the differences of the maintenance costs by housing areas and characteristics of the expenditure trends. After all, this paper contributes to the improvement of the reliability and the practicality for the Life Cycle Cost modeling and the maintenance cost estimating.

• Korean Journal of Construction Engineering and Management
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• v.19 no.5
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• pp.43-52
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• 2018

Generally, research on construction cost has been done mostly regarding its direct cost, thus model regarding indirect cost lacks attention. This research seeks to introduce a model to predict on-site overhead cost for apartment construction projects, which constitutes a big portion in Korean construction industry. We devised an equation of 9th degree via curve-fitting, using multiple on-site actual expense data, which can be used to calculate per-progress rate, per-day on-site overhead cost. We further show prospective usage of the model by applying it on construction projects sizing about 30 billion won. Regarding the fact that previous studies could not recognize pattern changes of a total on-site overhead cost, this model is worthy of its conveniency and thoroughness, as well as providing reasonal ground for its derivation in predicting on-site overhead cost of apartment construction projects.

• Journal of Construction Engineering and Project Management
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• v.3 no.1
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• pp.1-9
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• 2013

Construction is a competitive industry and successful contractors must be able to win bids to obtain projects. Cash flow analysis not only determines actual profit at the end of the project, but also estimates required cash resources or cash ballances at the end of every month. Cash flow analysis is important in managing a construction project; however, it requires extensive information that is not immediately available to the general contractor. Before contractors can perform cash flow analysis, they must first complete a series of pre-requisites such as the quantity take off, scheduling, and cost estimating, followed by accurate assessments of project costs incurred and billable progress made. Consequently, cash flow analysis is currently a lengthy, uncertain process. This paper suggests improved cash flow analysis can be developed using data extraction in Building Information Modeling (BIM). BIM models contain a wealth of information and tools have been developed to automate a series of process such as quantity takeoff, scheduling, and estimating. This paper describes a prototype tool to support BIM-based, automated cash flow analysis.

• Korean Journal of Construction Engineering and Management
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• v.12 no.6
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• pp.65-78
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• 2011

Construction business, which is complex and long-term business, requires accurate estimation and verification in construction costs and payment procedure from project planning to the completion of construction phase. And more importantly, it is necessary to investigate and determine the risk factors related to construction costs during the entire process including design planning, construction drawings, and quantity calculating. But, currently, it is not seem to be adequate to cope with the risk and increased construction costs against the operational budget in terms of actual costs when screening and estimating the bidding cost of public apartment. Therefore, this study selected and analyzed 40 sites' report of construction completion account from 2004 to 2010 focused on the adequacy on the modification of contract and design planning and on the complication of the budget in the beginning of the project. This study deducted various risk causes and results by analyzing actual costs according to year, architectural area, region, construction cost and sale/lease classification. We could find out construction risk according to annual variation of government policy and economy, and also deducted risk items by construction characteristic according to region and architectural area. Study result, we first found out the problems of lowest price award system according to the construction costs. The weight of the cost increase risk was analyzed that subcontract and material costs are very high. Roof and tile work were analyzed highly in subcontract cost risk and reinforcing bar and cement were analyzed highly in material cost risk, among direct construction cost. Finally, this study results could be used in comparing the categories of the construction costs made by specific construction process, belonging to the construction costs, with the operational budget made in the beginning of the project that can enable to grasp unpredictable risks over the construction costs and making quantitative analysis for it through analyzing the range of fluctuation and variations led by the fluctuations in the actual construction costs.

• Proceedings of the Korean Institute Of Construction Engineering and Management
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• 2008.11a
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• pp.207-211
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• 2008

The importance of cost management in early stage has been increasing due to market change and competition severence in construction industry. Because the adjustable budget is only 20% after finishing design stage, the critical decision is made in the early stage. However, in the early stage, the design information is not enough to make crucial decision. Therefore, this research suggests the predicting method on the purpose of accurate cost estimation. The parametric estimation is appropriate for the early stage, especially it has the strength of rapidity in cost estimation. This research analyzes 84 actual data of public apartment on the scale of $11{\sim}15$ stories, and then performs the correlation analysis between cost and influence factors. After eliminating the parameters which causes the problem of multicollinearity, this research derived the formula through the multi-regression analysis.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.14 no.11
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• pp.972-980
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• 2002

This work is aimed at estimating the effects of various factors on the energy consumption of Korean-style apartment houses using TRNSYS. The factors considered here include the nominal size of floor area, type of remodeling, azimuth, sidewall insulation, and window type. Based on some assumptions, an actual apartment house is simplified into a model that is used for thermal load calculations. The simplified model is validated by showing a good agreement with the actual one in the predicted result. Remodeling balconies into unconditioned buffer spaces yields a favorable thermal performance in comparison with the original type regardless of the nominal size. Incorporating balconies into a conditioned indoor space leads to sharp increases in thermal loads, which must be avoided in view of energy conservation as well as structural problem. A quantitative assessment on the azimuthal effect indicates that the heating energy can be saved up to 16％ by taking the south or southeast direction. Reduction in the heating load with enhancing the sidewall insulation is gradual, so that a cost-effectiveness analysis may be needed when amending the regulations concerned. Glazing appears to significantly affect the heat transfer through window. A typical case illustrates that the heating load is decreased about 25％ by simply adopting triple glazing instead of double glazing.

• Proceedings of the Korea Information Processing Society Conference
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• 2007.05a
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• pp.155-159
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• 2007

S/W 개발 프로젝트의 품질, 비용, 개발 기간을 잘 관리하여 프로젝트를 성공시키기 위해 PM 은 프로젝트의 종료시점과 예산의 초과를 예측할 수 있어야 한다. PMBOK 의 비용관리의 Earned Value Method 는 프로젝트의 진행에 따른 생산성의 변화와 그에 따른 비용과 일정의 증가 추정에 대한 규칙을 제시한다. 그러나 EVM 은 제조공정에서는 그 효과를 증명하였지만, S/W 프로젝트에서는 적용이 힘들어 잘 활용되고 있지 않다. 이는 사람이 주요 자원인 S/W 프로젝트에서는 Actual Cost 의 측정이 쉽지 않기 때문이다. 따라서 본 논문에서는 S/W 프로젝트 관리에서 Earned Value 의 측정이 쉽지 않아 추정되기 힘든 지연된 종료 시점에 대한 예측을 PMBOK 과 CMMI 에서 제시하는 관리 영역과의 연관성을 활용하고, EVM 을 보완하여 지연에 대한 예측모델을 만들어보고자 한다.

• Proceedings of the Korea Society for Simulation Conference
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• 2001.10a
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• pp.354-358
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• 2001

Cosim (Hardware and Software Co-Simulator) is a JavaBeans-based simulation tool fur validating systems architecture and estimating performance of web applications. Cosim has four components: Modeler, Translator, Engine and Scenario. Users start from Modeler to describe systems architecture in UML(Unified Modeling Language) deployment diagram, and then specify hardware & software performance parameters such as execution delay, network topology, and frame size. All information specified on Modeler are sent to Translator, and then automatically converted to Java programs. Scenario is responsible to run the Java program and produce results in text reports and graphs. Developers can reduce development time and cost by validating systems architecture of web applications before the actual deployment.

• Korean Management Science Review
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• v.19 no.1
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• pp.29-38
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• 2002

Due to the rapid increase In the Internet traffic volume, ISPs are faced with the definite need of the expansion of server capacity. In order to Provide prompt services for customers and still prevent excessive facility cost, it is critical to determine the optimum level of internet server capacity. The purpose of this Paper is to provide a simple but effective strategy on the expansion of servers capacity according to the increase in internet traffic. We model an internet server as an M/G/m/m queueing system and derive an efficient method to compute the loss probability which, In turn, Is used as a basis to determine proper server capacity. The Process of estimating the traffic parameter values at each server based on log data analysis is also given. All the procedures are numerically demonstrated through the process of analyzing actual log data collected from a game company.

• Journal of Advanced Marine Engineering and Technology
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• v.12 no.3
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• pp.57-67
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• 1988

Although handicapped by the inability to bridge the size gap between small laboratory sample and large engineering component, the V charpy test sample method does possess certain advantages, such as each of preparation, simplicity of test method, speed, low cost in test machinery, and low cost per test. On the other hand, the COD test method does posses advantages, which reduce the size gap between the laboratory sample and actual engineering component. Consequently, the correlation between V charpy absorbed energy and the critical COD value is required for estimating critical COD value from the simple V charpy test results. In this paper, the high tensile strength steel AH36 plate specimens having a single edge cracked notch were investigated to find out the correlation between V charpy absorbed energy and critical COD value in the welded parts under such various welding methods as shielded metal arc welding, the submerged arc welding and the electro gas welding by means of V charpy impact test and static 3-point bending test. Main results obtained are as follow ; 1. The relationships between V charpy absorbed energy Wc' and critical COD value ($\delta_c$)show; $\delta_c$=0.0065 Wc'+0.1906. 2. Ductile- brittle transition behaviours can be estimated by means of fracture appearance and general yielding behaviours. 3. The V charpy absorbed energy of SMAW is higher than that of SAW, EGW and similar relationships are obtained in the COD tests.