• Korean Journal of Construction Engineering and Management
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• v.5 no.3 s.19
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• pp.146-152
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• 2004

Consideration of factors driving crew productivities is imperative for accurate construction time estimation. Their impacts need to be well understood by estimators. There have been, however, little studies that quantified relationships between crew productivities and factors. This paper quantifies impacts of $^{\circ}A$ECrew size $^{\circ}\phi$ on crew productivities, for three highway concrete bridge activities, namely Column, Cap, and Deck, based on data compiled from 17 on-going highway projects in Texas State, USA. It was found that, for Bridge Deck operation, an increase of one crew-worker of formwork and rebarwork by one, leads to an increase of the productivity (cy/crew day) by 2.5 and 2.9, respectively. For the other activities, larger crew sizes did not lead to better crew productivities.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2016.05a
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• pp.223-224
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• 2016

Recent local advantages to improve the aesthetics of building materials connected with one of the trend of Exposed Concrete and Construction Method in various facilities and to diversify Showing a tendency to both application and development. This exposed concrete form of the features and materials is, the impact of large commercial viability and can consider I can apply to the surface of construction on a surface The diversification of the material was soon exposed directly linked to the varying aesthetics of concrete, and currently take advantage of the form of material is based on such important factor in our country Based on the concept of Exposed Concrete utilized by some construction site, design and be considered is very important elements of the put to practical use.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2018.05a
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• pp.33-34
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• 2018

Currently, free-form building has been increased worldwide. However, as a finishing material of free-form building, the production of free-form concrete panels(FCPs) spends lots of cost and efforts since it is difficult to reuse the FCP formwork and lots of workers are needed to make free-form curve. In addition, the technology to produce the FCP economically and easily is insufficient. Therefore, the objective of this study is a basic study regarding production management for developing free-form concrete panels. To achieve the objective, the property of FCP and condition for effective production management and production process are analyzed. The results of this study can utilize to develop the algorithm for FCP production management.

• Journal of KIBIM
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• v.1 no.1
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• pp.13-17
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• 2011

Currently, a lot of design, engineering and construction companies has been interested in BIM(Building Information Modeling) technologies for higher productivity and efficiency. The information provided from BIM can be mostly used for automated quantity takeoff. But BIM has some problems for fully automated quantity takeoff to solve. The purpose of this study is to show the problems and suggest solutions through case study, especially with concrete and form work.

• Journal of the Korea Safety Management & Science
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• v.14 no.3
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• pp.39-48
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• 2012

Risk Assessment to list possible safety disasters and their probability and severity is the starting point for effective safety management on construction project site. However, the safety managers in owners, construction supervisors, contractors, and sub-contractors still have difficulties in judging the priorities of safety activities and preparing responses to each potential safety disasters. Therefore, this study aimed to suggest a systematic method in assessing safety risk prior to commencement with the agreement of stakeholders. FMECA(failure mode effects and criticality analysis) was selected as a main assessment tool and it was modified according to the characteristics of construction projects and trades. Each risk is, firstly, evaluated with occurrence probability, possible loss and impacts to projects, and detections, and then risk priority number(RPN) is calculated. Subsequently, the managers of each stakeholder discuss the types, timing, and responsibilities of responses as a group decision-making process.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 1999.10a
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• pp.176-183
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• 1999

This paper describes the application of discretized continuum-type optimality criteria (DCOC) for the reinforced concrete continuous beams. The cost of construction as objective function which includes the costs of concrete, reinforced steel, formwork is minimized. The design constraints include limits on the maximum deflection in a given span, on bending and shear strengths, optimality criteria is given based on the well known Kuhn-Tucker necessary conditions, followed by an iterative procedure for designs when the design variables are the depth and the steel ratio. The self-weight of the beam is included in the equilibrium equation of the real system. Two numerical examples of reinforced concrete continuous beams with rectangular cross-section are solved to show the applicability and efficiency for the DCOC-based technique

• Proceedings of the Computational Structural Engineering Institute Conference
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• 1997.10a
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• pp.171-178
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• 1997

This paper describes the application of discretized continuum-type optimality criteria (DCOC) for the multispan partially prestressed concrete beams. The cost of construction as objective function which includes the costs of concrete, prestressing steel, non-prestressing steel and formwork is minimized. The design constraints include limits on the maximum deflection, flexural and shear strengths, in addition to ductility requirements, and upper and lower bounds on design variables as stipulated by the design code. Based on Kuhn-Tucker necessary conditions, the optimality criteria are explicitly derived in terms of the design variables-effective depth, eccentricity of prestressing steel and non-prestressing steel ratio. The prestressing profile is prescribed by parabolic functions. The self-weight of the structure is included in the equilibrium equation of the real system, as is the secondary effect resulting from the prestressing force. Two numerical examples of multispan PPC beams with rectangular cross-section are solved to show the applicability and efficiency fo the DCOC-based technique.

• Proceedings of the Korea Concrete Institute Conference
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• 1996.10a
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• pp.440-446
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• 1996

In this study, a procedure for the economic design of reinforced concrete beams under several design constraints is outlined on the basis of discretized continuum-type optimality criteria (DCOC). The costs to be minimized involve those of concrete, reinforcing steel and formwork. The design constraints include limits on the maximum deflection in a given span, on bending and shear strengths, in addition to upper and lower bounds on design variables. An explicit mathematical derivation of optimality criteria is given based on the well known Kuhn-Tucker mecessary conditions, followed by an iterative procedure for designs when the design variables are the depth and the steel ratio. Self-weight of the spans is also included in the equilibrium equation of the real system and in the optimatlity criteria.

• Proceedings of the Korea Concrete Institute Conference
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• 2005.05b
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• pp.45-48
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• 2005

Self compacting concrete has the strong point in capability of concrete to be uniformly filled and compacted in every corners of formwork by its self-weight without vibration during placing. However, powder type self compacting concrete has the weak point in the heat of hydration, the drying shrinkage and the elastic property of concrete etc. Recently viscosity agent has been developed in order to overcome these weaknesses. In this study, self compacting concrete is made with viscosity agent based on polysaccharide derivative in order to develope the normal strength self compacting concrete. Slump flow, loss of slump flow and setting time are measured for comparison with normal concrete. Compressive strength, freezing and thawing test and carbonation test are conducted on normal and self compacting concrete using viscosity agent. In the experiment, we acquired good results in fresh and hardened self compacting concrete using viscosity agent based on polysaccharide derivative.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2019.05a
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• pp.61-62
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• 2019

With development of IT technology, the ubiquitous has been realized in various industry. In construction industry, as well, end-edge techniques have been introduced such as managing technique the temperature and compressive strength of the concrete placed in structure in domestic and abroad project sites. However, several problems were found during application at the actual field regarding difficulties of connecting Bluetooth communication due to the short communication range, diffuse reflection caused by aluminum formwork, and high cost by using one-time sensor. Therefore to recover these shortages, and improve the performances, the wireless sensor network based concrete IoT management system for concrete early-age quality management was developed.