• 국제학술발표논문집
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• The 9th International Conference on Construction Engineering and Project Management
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• pp.792-799
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• 2022

Building Information Modeling (BIM) technology is a key component of modern construction engineering and project management workflows. As-is BIM models that represent the spatial reality of a project site can offer crucial information to stakeholders for construction progress monitoring, error checking, and building maintenance purposes. Geometric methods for automatically converting raw scan data into BIM models (Scan-to-BIM) often fail to make use of higher-level semantic information in the data. Whereas, semantic segmentation methods only output labels at the point level without creating object level models that is necessary for BIM. To address these issues, this research proposes a hybrid semantic-geometric approach for clutter-resistant floorplan generation from laser-scanned building point clouds. The input point clouds are first pre-processed by normalizing the coordinate system and removing outliers. Then, a semantic segmentation network based on PointNet++ is used to label each point as ceiling, floor, wall, door, stair, and clutter. The clutter points are removed whereas the wall, door, and stair points are used for 2D floorplan generation. A region-growing segmentation algorithm paired with geometric reasoning rules is applied to group the points together into individual building elements. Finally, a 2-fold Random Sample Consensus (RANSAC) algorithm is applied to parameterize the building elements into 2D lines which are used to create the output floorplan. The proposed method is evaluated using the metrics of precision, recall, Intersection-over-Union (IOU), Betti error, and warping error.

• Current Optics and Photonics
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• 제2권2호
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• pp.119-124
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• 2018

The errors in retrieved aerosol backscattering coefficients due to different lidar ratios are analyzed quantitatively in this paper. The actual calculation shows that the inversion error of the aerosol backscattering coefficients using the Fernald backward-integration method increases with increasing inversion distance. The greater the error in the lidar ratio, the faster the error in the aerosol backscattering coefficient increases. For the same error in lidar ratio, the smaller actual aerosol backscattering coefficient will get the larger relative error of the retrieved aerosol backscattering coefficient. The errors in the lidar ratios for dust or the cirrus layer have great impact on the retrievals of backscattering coefficients. The interval between the retrieved height and the reference range is one of the important factors for the derived error in the aerosol backscattering coefficient, which is revealed quantitatively for the first time in this paper. The conclusions of this article can provide a basis for error estimation in retrieved backscattering coefficients of background aerosols, dust and cirrus layer. The errors in the lidar ratio of an aerosol layer influence the retrievals of backscattering coefficients for the aerosol layer below it.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2019년도 추계 학술논문 발표대회
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• pp.14-15
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• 2019

In this paper, it was tried to prove the possibility and effect of coordinate measurement by using MEP layout equipment at the construction stage, and to propose a method to improve measurement accuracy during construction. For this study, the passenger terminal site, which is a long span structure, was selected and compared with three dimensional CAD drawings and construction measurement results using MEP layout equipment for the precise construction of long-span irregular curved roof layers. As a result, it was found that it is possible to construct three-dimensional curved roof layers using MEP layout equipment through measurement and analysis.

• 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.

• 한국건설관리학회논문집
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• 제15권5호
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• pp.22-30
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• 2014

본 논문은 시기별 국내 건설경기 변화와 해외건설수주 간의 관계성을 벡터오차수정모형을 통해 비교분석하는 것을 목적으로 한다. 분석결과 IMF 외환위기 이후에는 주거용 건설경기가 하락할 경우에만, 해외건설시장 진출이 더욱 활발히 나타나는 것으로 확인되었다. 게다가 IMF 외환이기 이전보다 외환위기 이후에는 국내 주거용 건설경기 변화에 즉각적으로 반응하여 해외건설시장 진출 규모가 확대되는 것으로 나타났다. 이와 같은 현상은 국내 건설업체들의 사업 포트폴리오 상 주거용 건설경기에 매우 민감하게 반응할 수밖에 없음에 기인한다. 즉 국내 주택시장 침체는 국내 건설업체의 경영상태에 심각한 영향을 미치게 되고, 이를 긴급히 타개하기 위하여 해외건설시장 진출 규모를 확대한 것으로 판단된다. 본 연구에서 분석을 통해 확인한 바와 같이 주택경기 침체에 따른 건설업체 경영상태 악화를 개선하기 위하여 해외건설시장 진출의 외연적확대는 오히려 건설업체 경영상태를 더욱더 악화시키는 결과를 초래한 것이다. 이에 따라 급박한 상황에서의 사업 전환은 오히려 수익률 확보보다 회사 내 현금흐름 확보를 위한 수단으로 전락할 수도 있기 때문에 전략적 유연성을 확보할 수 있도록 사업 다각화 수준을 지속적으로 일정 범위 안에서 관리할 필요가 있을 것으로 판단된다.

• Journal of Korean Vacuum Science & Technology
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• 제2권2호
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• pp.57-62
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• 1998

The resonance frequencies, shunt impedances and Q-values for the higher-order modes in our designed cavity are calculated by the computer codes URMEL and MAFIA. A new computer code is developed to calculate the complex tune shifts for the randomness of the higher-order mode frequencies due to the construction errors of a cavity. The results with the construction errors are compared to those fo without error cases for the dipole mode and quadrupole mode.

• 국제학술발표논문집
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• The 3th International Conference on Construction Engineering and Project Management
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• pp.606-615
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• 2009

Estimating the reasonable construction-cost according to the construction phase in public construction is an important element for securing and executing a national budget efficiently. As a general rule, the predetermined cost of construction is estimated at the end of the design of the target structure. Therefore, it seems to be a considerably difficult problem to estimate the approximate cost of construction, only with its basic information of the bridge in the design planning phase and the early design stage where we can not have specific detailed-section of the target structure. In this paper, we present the calculation of construction-cost in the planning phase based on the analysis of factors affecting the cost of construction conducted in the previous study. Beside, to estimate the cost of construction in early design phase, we would like to present the calculation of construction-cost in the early design phase by executing the analysis of data collected from 61 steel box bridges. It was found from the result of study that the estimated cost of construction gained by the calculation of construction-cost in this paper reduces the error between the real cost of construction and that by the existing method of using.

• Journal of Construction Engineering and Project Management
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• 제4권4호
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• pp.9-16
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• 2014

The purpose of this paper is to develop a model for forecasting early design construction cost of building projects using Artificial Neural Network (ANN). Eighty questionnaires distributed among construction organizations were utilized to identify significant parameters for the building project costs. 169 case studies of building projects were collected from the construction industry in Gaza Strip. The case studies were used to develop ANN model. Eleven significant parameters were considered as independent input variables affected on "project cost". The neural network model reasonably succeeded in estimating building projects cost without the need for more detailed drawings. The average percentage error of tested dataset for the adapted model was largely acceptable (less than 6%). Sensitivity analysis showed that the area of typical floor and number of floors are the most influential parameters in building cost.

• 토지주택연구
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• 제8권1호
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• pp.23-29
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• 2017

The BIM design is expected to expand to the domestic and overseas construction industries, depending on the effect of construction productivity and quality improvement. However, with the obligation of Public Procurement Service to design the BIM design, it includes a design error and the problem of utilization of 3D design by choosing a simple 2D to 3D remodelling method that can not be modelled in 3D modeling or use of the construction and maintenance phases. The results reviewed by BIM design results were largely underutilized and were not even performed with the verification of the error. In order to resolve this, one must develop the check system that secures the quality of BIM design and ensure that the reliability of BIM results are available. In this study, it is designed to develop a program that can automatically verify the design of the BIM design results such as violation of the rules of the BIM design, design flaws, and improve the usability of the BIM design. In particular, this programs were developed not only to identify programmes that were not commercially available, but also to validate drawings in low-light computer environments. The developed program(LH-BIM) store the information of attribute extracted from the Revit file(ArchiCAD, IFC file included) in the integrated DB. This provides the ability to freely lookup the features and properties of drawings delivered exclusively by the LH-BIM Program without using the Revit tools. By doing so, it was possible to resolve the difficulties of using traditional commercial programs and to ensure that they operate only with traditional PC performance. Further, the results of the various BIM software can be readily validated, which can be solved the conversion process error of IFC in the case of SMC. Additionally, the developed program has the ability to automatically check the error and design criteria of the drawings, as well as the ability to calculate the area estimation. These functions allow businesses to apply simple and easy tasks to operate tasks of BIM modelling. The developed system(LH-BIM) carried out a verification test by reviewing the review of the BIM Design model of the Korea Land & Housing Corporation. It is hoped that the verification system will not only be able to achieve the Quality of BIM design, but also contribute to the expansion of BIM and future construction BIM.

• 한국건축시공학회지
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• 제20권2호
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• pp.155-162
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• 2020

본 연구에서는 비정형 패널 제작 기술력 향상을 위한 기초적인 연구로 비정형 패널의 오차율을 분석하였다. 이에 본 연구에서는 우선적으로 비정형 패널 제작시 매끄러운 형상을 표현하기 위해 콘크리트 대신 혼합모르타르를 사용하여 적정 배합비를 도출하였다. 그 후 도출한 배합비를 적용하여 비정형 패널을 CNC장비를 통해 제작하였으며 패널의 오차율을 분석하였다. 본 연구에서는 두 가지의 배합을 선정하였으며 선정한 첫 번째 배합은 혼합시멘트 페이스트 배합, 두 번째 배합은 혼합모르타르 배합이었다. 실험결과 두 배합모두 품질적 측면에서 만족하는 정량적 수치를 보였다. 하지만 두 배합모두 양생하는 방법에 차이를 두었고 이로 인해 오차가 발생했다. 이를 통해 오차율은 사용재료의 특성과 재료 간 화학반응의 문제보다는 패널을 양생하는 방법에 따라 더 많은 영향을 끼치는 것으로 판단하였다. 본 연구는 현재 기초적인 연구수행으로 추후 본 연구를 토대로 추가적인 연구를 진행한다면 콘크리트 타설시 흘러내림을 방지하는 방안과 오차율을 줄일 수 있는 양생방법을 찾는 연구가 함께 병행되어야 한다. 위와 같은 연구수행을 통해 비정형 패널 제작에 대한 연구 및 개발에 기여할 수 있으며 나아가 비정형 건축시장에서 경쟁력을 확보할 수 있다.