• Steel and Composite Structures
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• 제45권1호
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• pp.67-82
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• 2022

In this paper, buckling and free vibration of imperfect, functionally graded beams, including porosities, are investigated, using a higher order shear strain theory. Due to defects during the manufacturing process, micro porosities may appear in the material, hence the appearance of this imperfection in the structure. The material properties of the beams are assumed to vary regularly, with power and sigmoid law, in the direction of thickness. A novel porosity distribution affecting the functionally graded volume fraction is presented. For the compact formulation used for cementite-based materials and already used in P-FGM, we have adapted it for the distribution of S-FGM. The equations of motion in the FG beam are derived using Hamilton's principle. The boundary conditions for beam FG are assumed to be simply supported. Navier's solution is used to obtain the closed form solutions of the FG beam. The numerical results of this work are compared with those of other published research to verify accuracy and reliability. The comparisons of different shear shape functions, the influence of porosity, thickness and inhomogeneity parameters on buckling and free vibration of the FG beam are all discussed. It is established that the present work is more precise than certain theories developed previously.

• Journal of Construction Engineering and Project Management
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• 제5권2호
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• pp.11-15
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• 2015

The Last PlannerSystem (LPS) has been implemented on construction projects to increase work flow reliability, a precondition for project performance againstproductivity and progress targets. The LPS encompasses four tiers of planning processes:master scheduling, phase scheduling, lookahead planning, and commitment / weeklywork planning. This research highlights deficiencies in the current implementation of LPS including poor lookahead planning which results in poor linkage between weeklywork plans and the master schedule. This poor linkage undetermines the ability of theweekly work planning process to select for execution tasks that are critical to projectsuccess. As a result, percent plan complete (PPC) becomes a weak indicator of project progress. The purpose of this research is to improve lookahead planning (the bridgebetween weekly work planning and master scheduling), improve PPC, and improve theselection of tasks that are critical to project success by increasing the link betweenShould, Can, Will, and Did (components of the LPS), thereby rendering PPC a betterindicator of project progress. The research employs the case study research method to describe deficiencies inthe current implementation of the LPS and suggest guidelines for a better application ofLPS in general and lookahead planning in particular. It then introduces an analyticalsimulation model to analyze the lookahead planning process. This is done by examining the impact on PPC of increasing two lookahead planning performance metrics: tasksanticipated (TA) and tasks made ready (TMR). Finally, the research investigates theimportance of the lookahead planning functions: identification and removal ofconstraints, task breakdown, and operations design.The research findings confirm the positive impact of improving lookaheadplanning (i.e., TA and TMR) on PPC. It also recognizes the need to perform lookaheadplanning differently for three types of work involving different levels of uncertainty:stable work, medium uncertainty work, and highly emergent work.The research confirms the LPS rules for practice and specifically the need to planin greater detail as time gets closer to performing the work. It highlights the role of LPSas a production system that incorporates deliberate planning (predetermined andoptimized) and situated planning (flexible and adaptive). Finally, the research presents recommendations for production planningimprovements in three areas: process related, (suggesting guidelines for practice),technical, (highlighting issues with current software programs and advocating theinclusion of collaborative planning capability), and organizational improvements(suggesting transitional steps when applying the LPS).

• 대한토목학회논문집
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• 제28권4D호
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• pp.505-512
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• 2008

단지개발사업은 다양한 구조물이 결합된 사업으로 과거에는 주거, 상업단지 등 단일목적을 갖는 사업위주로 진행되었으나, 최근에는 IT 기술의 발전, 삶의 질 향상 및 생활패턴 변경 등에 따라 U-city를 비롯한 다양한 목적을 갖는 복합단지 형태의 개발이 이뤄지고 있다. 이러한 단지개발과 관련된 인적자원은 각 대학의 도시계획 및 공학, 토목 및 건축공학과에서 이뤄지고 있으며, 도시계획 및 도시공학과에서는 단지개발계획을, 토목 및 건축공학과는 계획을 바탕으로 하는 설계 및 시공과 관련한 교육을 담당하고 있다. 사업의 원활한 진행을 위해 계획 및 설계, 시공은 연속적으로 이뤄져야 하나 현재의 교육과목을 살펴보면 이러한 연속성을 기대하기에는 어려움이 있다. 이에 단지개발 계획수립의 전문가 가 기초적인 엔지니어링 지식을 확보하고 또한 단지개발사업의 설계 및 시공인력은 단지계획 전반을 이해할 수 있도록 기존의 교과목 또는 내용이 개선되어야 할 필요가 있다. 이에 본 연구는 기존 도시계획 및 공학과와 단지개발의 주요 구조물 설계 및 시공과 관련한 토목공학 관련 학과의 교육 내용을 살펴보고, 두 학과의 업무교차가 발생하는 설계단계에 대해 업무를 수행하는 전문인력을 대상으로 업무 중요성을 조사하였다. 이를 통해 단지개발 사업진행 간 설계업무를 이해하고 이와 관련한 설계업무의 효율성을 개선하기 위한 방안을 제시하고자 한다.

• 대한토목학회논문집
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• 제34권3호
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• pp.999-1006
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• 2014

국토해양부에서 2011년 시설물별 탄소배출량 산정가이드라인을 통해 제시한 토공장비의 $CO_2$ 배출계수는 IPCC 탄소배출계수를 활용하여 연료사용량을 기반으로 만들어졌다. 하지만 이 방식은 현장의 다양한 조건을 반영하지 못한다는 단점이 있다. 따라서 이러한 단점을 보완한 새로운 배출계수가 필요하다. 본 연구에서는 토공장비를 대상으로 농도-유속측정(C-FVM)을 이용한 직접측정방식으로 $CO_2$ 배출량을 산정하고, 국토해양부에서 제시한 배출계수와 비교분석 후 토공장비의 새로운 $CO_2$ 배출계수를 제시하고자 한다.

• 한국재난정보학회 논문집
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• 제10권1호
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• pp.15-24
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• 2014

본 연구는 설계 과정의 분해, 시공 과정의 조립, 공사비 적산 등 공사의 계획과 관리에 걸친 모든 공사 관리의 업무를 체계화할 수 있는 공동주택의 공사정보분류체계를 제시하였다. 또한, 본 연구는 이 공사정보분류체계를 작업순서에 따라 관계형 데이터베이스(Data Base)로 구축 방법을 제시하였고, 구축된 데이터베이스를 근거로 적산 자동화 시스템 개념 모형을 구축하였다. 이러한 적산 자동화 시스템 개념 모형은 기존 적산 시스템들의 근본적인 문제점이었던 부적절함을 해소하여 공동주택 건설현장에서 효과적으로 적용가능한 과학적인 적산 시스템으로 활용할 수 있을 것이다.

• 대한토목학회논문집
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• 제30권5D호
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• pp.461-465
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• 2010

본 연구의 목적은 예비타당성조사에서 수행한 도시부 간선도로 확장공사로 인한 부(-)의 편익을 산정하고 이것이 경제성 평가에 미치는 영향을 분석하는 것이다. 북부간선도로 태릉-구리 간 확장사업의 실제 예비타당성조사 단계에서 통상적인 편익 산출 방법론을 적용하였으며, 공사로 인한 차량운행비용, 통행시간, 교통사고, 환경비용의 부(-)의 편익을 산출하였다. 분석 결과, 부(-)의 편익의 적용여부는 사업의 경제적 타당성 평가에 많은 영향을 주는 것으로 나타났다. 하지만 공사기간, 공사의 종류, 공사구간 및 교통량 등에 따라 부(-)의 편익에 많은 영향을 주는 감소되는 용량 및 자유속도가 현저하게 다를 수 있으며, 향후에는 이러한 요소와 용량 및 자유속도에 대한 상세한 연구가 필요할 것이다.

• 대한안전경영과학회지
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• 제14권4호
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• pp.23-29
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• 2012

There are insufficient models that find problems and solutions for accident prevention through risk assessment and suggest safe work process and work instruction from foundation works to finish work for accident decrease. This paper presents a quantitative risk assessment model by analysis of risk factors in each process such as appurtenant works, temporary works, structural works, equipment work, finishing work and etc based on accident examples and investigation on actual condition in plants construction work. In addition, the safety management system was developed to perform risk assessment of plants construction and use it for effective safety training for labor.

• 한국BIM학회 논문집
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• 제3권3호
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• pp.9-18
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• 2013

In case of applying the BIM method in the civil engineering of irregularly shaped structure, BIM method began to be introduced in the current building engineering area compared with the expected effects of the relatively high construction productivity has been recognized. In this paper, I have developed quantity calculation algorithms applying it to earthwork and bridge construction, tunnel construction, retaining wall construction, culvert construction and implemented BIM based 3D-BIM Modeling quantity calculation. Structure work in which errors occurred in range between -6.28% ~ 5.17%. Especially, understanding of the problem and improvement of the existing 2D-CAD based of quantity calculation through rock type quantity calculation error in range of -14.36% ~ 13.07% of earthwork quantity calculation. It's benefit and applicability of BIM method in civil engineering. In addition, routine method for quantity of earthwork has the same error tolerance negligible for that of structure work. But, rock type's quantity calculated as the error appears significantly to the reliability of 2D-based volume calculation shows that the problem could be. Through the estimating quantity of earthwork based 3D-BIM, proposed method has better reliability than routine method. BIM, as well as the design, construction, maintenance levels of information when you consider the benefits of integration, the introduction of BIM design in civil engineering and the possibility of applying for the effectiveness was confirmed. In addition, as the beginning phase of information integration, quantity document automation program has been developed for activation of BIM. And automatically enter the program code number, linkage and manual volume calculation program, quantity document automation programs, such as the development is now underway, and step-by-step procedures and methods are presented.

• 대한토목학회논문집
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• 제32권1D호
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• pp.41-49
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• 2012

정보기술 중에서 오랫동안 제조업 분야에서 군림해왔던 바코드 기술을 대체하고 있는 RFID 기술은 제조업뿐만 아니라 국방, 물류, 운동, 건설 등 산업 전반에서의 그 활용 효과가 입증되고 있다. 건설 분야에서도 건축을 중심으로 RFID를 적용하려는 연구들이 계속되고 있지만 단순 공종 또는 자재관리용도의 실험적 적용이 대부분이었다. 이에 본 연구에서는 대표적인 토목공사인 터널공사의 NATM 공법에 대하여 5개 시공 프로세스의 사이클 타임 분석을 목적으로 시공단계별 RFID 적용 방법론을 제시하였고, 실제 현장 적용을 통해 방법론을 검증하였다. 이로써 각 시공단계에서 RFID를 통해 실측 정보를 제공함으로써 향후 공정율 예측 및 후속공종 계획 수립시에 효과적으로 활용될 수 있으며, 토목분야에서의 RFID 현장 적용성을 확대하는 시도가 될 수 있을 것으로 기대된다.

• 한국안전학회지
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• 제33권2호
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• pp.76-85
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• 2018

The interest in the Building Information Modeling (BIM) technology has risen remarkably due to the effects on construction work period reduction, cost reduction, work safety improvement, and other factors. In civil engineering field, BIM applications mainly focus on data modeling and virtual construction. In this study, we present the BIM-based virtual construction and analyze the effects of BIM for the railway facilities so that the conventional approach to the equipment operation plan can be improved in order to prevent safety accidents which can result from unclear information during the operation plan. The BIM-based virtual construction technology is applied to establish the construction plan for the site with constraints, the installation of steel girder needs to be completed, avoiding interference with the existing high-speed railway operation within a given limited time. A virtual construction model consisting of topography, structures, equipments, and avatar was built and more detailed model, including safety guard rails, was then created. Specifications of the construction equipment were input as a database, and the virtual construction model was manipulated in the equipment operation planning. Through the BIM-based virtual construction, including the verification of alternative construction method, 311 million won was saved and the construction period was shortened by 87 days compared to the original plan. In addition, it was shown that the interest and participation of the construction workers can be increased by providing the 3D virtual scene for real construction work and various safety hazards occurring during equipment operation can be effectively removed in advance by the interactive worker education.