• 국제학술발표논문집
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• The 3th International Conference on Construction Engineering and Project Management
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• pp.1140-1147
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• 2009

Productivity measurement of construction machinery is a significant issue faced by many contractors especially those involved in earthwork projects. Traditionally, equipment production rate has been estimated using data available in manufacturers' catalogues, results of previous construction projects, or personal experience and assessments of the site personnel. Actual production rates obtained after the completion of a project demonstrate the fact that most of these methods fail to provide accurate results and as a direct consequence, may lead to unrealistic project cost estimations prepared by the contractors. What makes this more critical is that in most cases, inadequate cost estimations lead the entire project to exceed the initial budget or fall behind the schedule. In this paper, a linear regression method to estimate bulldozer productivity is introduced. This method has been developed using SPSS-16 software package. The presented method is used to estimate the productivity of Komatsu D-155A1 series which is commonly used in many earthmoving operations in Iran. The data required for the numerical analysis has been collected from actual site observation and productivity measurement of 60 pieces of D-155A1 series currently being used in several earthmoving projects in Iran. Comparative analysis of the output data of the presented regression method and the existing productivity tables provided by the manufacturer shows that when compared to the actual productivity data collected on the jobsite, a significant increase in accuracy and a remarkable reduction of data variance can be achieved by using the presented regression method.

• 국제학술발표논문집
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• The 5th International Conference on Construction Engineering and Project Management
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• pp.231-234
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• 2013

According to the recent development of USN technology, it has been applied in various fields of construction management. In particular, the concrete curing management using the wireless measurement system is actively being conducted. However, the existing method has limitations such as the reinstallation of temperature sensors and repositioning of repeaters. It is also not easy to acquire the measured data. Thus, this study focuses on the concrete curing management. This study proposes data acquisition method using the smartphone on construction site and tests applicability of the data measuring device and the smartphone. The test allows us to suggest the actual communication distance on construction site and to determine the correction value that is applied to the measured temperature. The data acquisition method proposed in this study is intended to enable appropriate management on construction site and will be able to be applied effectively to a variable construction site. It can also be used in all fields of construction management.

• 국제학술발표논문집
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• The 5th International Conference on Construction Engineering and Project Management
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• pp.488-493
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• 2013

Accurate initial cost estimates are essential to effective management of construction projects where many decisions are made in the course of project management by referencing the estimates. In practice, the initial estimates are frequently derived from historical actual cost data, for which standard distribution-based techniques are widely applied in the construction industry to account for risk associated with the estimates. This approach assumes the same probability distribution of estimate errors for any selected estimates. This assumption, however, is not always satisfied. In order to account for the probabilistic nature of estimate errors, an alternative method for measuring the risk associated with a selected initial estimate is developed by applying the Bayesian probability approach. An application example include demonstrates how the method is implemented. A hypothesis test is conducted to reveal the robustness of the Bayesian probability model. The method is envisioned to effectively complement cost estimating methods that are currently in use by providing benefits as follows: (1) it effectively accounts for the probabilistic nature of errors in estimates; (2) it is easy to implement by using historical estimates and actual costs that are readily available in most construction companies; and (3) it minimizes subjective judgment by using quantitative data only.

• 국제학술발표논문집
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• The 3th International Conference on Construction Engineering and Project Management
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• pp.153-160
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• 2009

The demand for super tall building construction is increasing worldwide. There has been a constant request for achieving early payback on investment by shortening the construction time. This pertains especially for the case of huge investment projects such as super tall building construction. It is very important to shorten the construction time for the building framework, which requires substantial construction time and cost, and this is directly related to the establishment of an optimum lift plan for construction. When there is a problem in the selection of the lift equipment, it is almost impossible to revise the selection, resulting in a possible failure of the project. Thus, the purpose of this study is to analyze the function and logic for the development of the process for the selection of lift equipment for super tall building projects and further development of making the analyzed process into a system. In line with this research objective, the process of selecting the optimum lift equipment by domestic construction company was investigated and analyzed as well as collecting the actual field data. The actual data were obtained by sensors installed on tower cranes at three construction sites with the help from the construction company.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2009년도 춘계 학술논문 발표대회 학계
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• pp.171-174
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• 2009

The standard estimation system, used to estimate the predetermined cost of construction work, is measured by the standard and typical construction methods and field conditions. And the standard estimation system is applied to basic data for the measuring of construction cost, such as the consumed quantity of material, labor hours, and machinery cost. However it does not reflect sufficiently for the diversity and reality of constructions work Therefore, this study is recognized the necessity of new cost estimation models for the rational construction cost estimation. To improve estimation technique and construction ability, it was analyzed labor hours, production volume based on the work crew in construction work.

• 한국재난정보학회 논문집
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• 제9권1호
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• pp.11-21
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• 2013

본 연구는 2004년 이후 도입된 실적 공사비 제도에 의하여 착공된 지하철 건설공사를 대상으로 실적공사비, 공사규모 그리고 시간을 고려하여 공사비를 예측하는 식을 제시하였다. 11개의 지하철공사 자료를 이용하여 지하철 공사비 예측을 위한 비용-규모 지수 n(신뢰범위:0.5~0.7)을 구한 결과, 총공사비 0.713, 순공사비 0.77로 도출되었다. 본 연구에서 제시한 공사비 예측 식 모델은 향후 지하철 공사 적용 현장의 사업기획, 예비조사, 타당성조사, 기본설계 단계에서 개산 공사비를 추정하는데 효과적으로 적용할 수 있을 것이다.

• 한국산학기술학회논문지
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• 제21권3호
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• pp.497-502
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• 2020

소요군에서 원하는 성능의 함정을 적기에 획득하기 위해서는 정확하게 일정을 예측하고 계획하여 함정을 건조해야 한다. 하지만 지금까지 함정의 건조기간을 산정한 연구를 살펴보면, 전문가 집단의 설문을 통한 주관적인 연구방법으로 수행되어 건조기간 산출의 정확성과 일관성이 부족하고, 실 데이터를 바탕으로 이루어진 학술적 연구는 없었다. 따라서 본 연구에서는 함정 건조기간 산출의 정확성을 높이고 일관성을 유지하기 위해 실 데이터를 바탕으로 선형회귀분석을 통해 예측 모델을 제시하고자 한다. 이를 위해 먼저 함정사업의 절차 및 특성을 이해하고 함정사업 유경험자를 대상으로 함정 건조기간에 영향을 미칠 것으로 추측되는 요인을 찾아보았다. 그 다음 과거 연구개발된 함정들의 실적을 바탕으로 함정 건조기간에 영향을 미칠 것으로 추측되는 요인들의 실 데이터를 최대치로 수집하고 단계적 회귀분석을 실시하였다. 그 결과 함정 건조기간에 영향을 미치는 요인으로 소요군 주관 시험평가 항목수, 장비수, 연구개발 장비수가 선정되었다. 수집한 데이터를 회귀방정식에 대입하여 내적 타당성을 확인해본 결과 평균 96.5%의 정확도를 보였다.

• 한국건축시공학회지
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• 제16권2호
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• pp.133-140
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• 2016

건설공사에 있어 노무량은 건설공사비 산정을 위한 기준으로 사용되고 있고, 건설산업의 생산성을 파악하는 근거자료로도 활용되고 있다. 하지만 노무량의 기준이라고 하는 표준품셈과 실제투입 노무량과 큰 차이를 보이고 있어 이를 해결할 수 있는 방안이 필요하다. 따라서 본 연구에서는 실제투입 노무량을 좀 더 정확하고 간편하게 입력할 수 있는 시스템을 구축하기 위하여 전통적인 종이와 펜을 이용한 수기방식을 그대로 따르면서 전자문서화에 대한 이중부담이 없는 디지털펜을 이용하는 방안을 제시하고자 한다. 본 연구를 통해 실투입 작업정보를 단순히 저장하는 것뿐만 아니라 웹을 통한 공유 및 활용을 통해서 공사비 산정업무의 생산성 측면에서도 기여할 것으로 사료된다.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2021년도 가을 학술논문 발표대회
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• pp.250-251
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• 2021

A subcontract work order is the basis of the construction process and consists of the root and trunk of the construction industry. The construction process through a subcontract work order is an important element of project success, and it is the basic unit of creating profit in the construction industry. Therefore, correct analysis and forecasting of subcontract work orders allow correct estimation of construction cost and profit which is the foundation of corporate decision making. This study has started to provide predictions of subcontractor's bidding-ratio for decision-making. Since the actual project data has been used in this study, the contribution level of the model is highly expected in actual field. The statistical confidential level of adjusted decision coefficient is concluded low because of limited sample numbers. However, its accuracy and confidence level can be increased through increasing sample numbers, considering more variables, and studying of reducing error.

• 한국환경과학회지
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• 제22권5호
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• pp.533-542
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• 2013

In this study, estimation methods for actual evapotranspiration have been studied using the concept of potential and actual evapotranspiration. Among the diverse estimation methods, SWAT-K application is chosen for hydrological modeling. For Jeju island we have characterized annual and monthly evapotranspiration using SWAT-K. In the results, simulated potential evapotranspiration reached to the 91% of small pan evaporation. With respect to the temperature lapse rate($-6^{\circ}C/km$) depending on the altitude of Halla mountain, evapotranspiration rate decreased by 7.5% compared to the status when the temperature data from the Jeju weather station were applied to the watershed. As the average of annual rainfall increased, potential evapotranspiration was increased, actual evapotranspiration was, however, decreased.