• Fashion & Textile Research Journal
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• v.20 no.6
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• pp.704-712
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• 2018

This study analyzed working postures using the Ovako Working Posture Analysis System (OWAS) to improve work clothes for construction workers. A video taken at a construction work site was stopped at regular intervals and the postures of relevant body parts proposed by OWAS was recorded. Additionally, based on analysis of the working postures code, the level of work action for each postures was classified from stage I to IV. General workers frequently straightened or bent forward at the waist, and used their legs to stand, bend, or walk. Wood workers moved extensively from the waist, keeping their legs relatively straight and their arms held below their shoulders, repeatedly tapping with a hammer weighing less than 10.0kg. Rebar bending workers mainly bent forward at the waist, with both legs bent or standing with one leg bent. Rebar transport and fixing workers walked with the waist straight, and occasionally one or both hands held above the shoulders. Their work also involved holding a hook, which weigh less than 10.0kg, in their hands, and the difficult task of lifting and placing long rebars, which weigh from 10.0 to 20.0kg or more. Concrete pouring workers bent or twisted their back to the side. Therefore, this study suggests that design goals should be different when developing workwear for each type of worker.

• Journal of the Korea Institute of Building Construction
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• v.14 no.1
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• pp.87-93
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• 2014

A tightened coupler with two way-threading is suggested to overcome the previous one-way threaded coupler. The experiment and a mock-up test were conducted to analyze the constructability of the suggested coupler. The aim of the mock-up test was to assemble the suggested coupler in horizontal rebar of mat footing and vertical rebar of semi-fabricated column bars. The method using the suggested coupler in semi-fabricated column bars is developed by analyzing the problem of fabricated column bars using the one-way threaded coupler. The result of the mock-up test showed that the time required to assemble the suggested coupler in the horizontal bars is shorter than it is for the one-way threaded coupler. In addition, the method using the suggested coupler in semi-fabricated column bars has advantages such as lower working loads, supporting safe work and strongly tightening the rebar. From these results, it is revealed that the suggested coupler is adequate to use in rebar work in terms of cost, quality and time.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.29 no.5
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• pp.447-454
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• 2016

In the meantime, looking at the present status of how to estimationte the quantity of rebar based on 3D BIM getting the limelight in these days, commercial BIM tools provide rebar modeling functions however it takes a vast amount of modeling time for modeling of rebar in use of that function hence there is no BIM software at present for practical use. Therefore, in this study, we organized and presented a practical rebar quantity estimationtion process in BIM-based design work-site and intended to develop a program named Rebar Automatic Arrangement Program - hereinafter called RAAP - which enables automatic rebar arrangement based on much more precise cross-sectional information of bars in column, beam, slab and wall than the one from existing 2D method under the conditions without any cross-sectional information in the initial design phase. In addition, we intended to establish rebar quantity estimationtion process in the initial design phase through interworking of modeling & quantity estimationtion functions in consideration of joint, anchoring length of BuilderHUB as a BIM software with RAAP. The results from this study are practical in developing a technology that is able to estimationte quantity with more improved reliability than the one from existing 2D-based methods with less effort when the quantity of framework is estimationted in the uncompleted state of cross-sectional design for structural members in the initial design phase of a construction project. And it is expected that it could be utilized as a basic study from which a reasonable quantity estimationtion program can be established in the initial design phase.

• Journal of the Korea Concrete Institute
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• v.18 no.2 s.92
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• pp.233-238
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• 2006

In lifetime estimation, the FEM analysis method is proposed for predicting corrosion failure time of concrete structures exposed to sea-water. This study shows that the corrosion rate of rebar in artificial pore solution can be transferred to the corrosion rate of rebar in concrete using the relationship between pore volume and concrete volume by Jennings' model. And this study considered the pitting corrosion effects of reinforcement bar on corrosion failure analysis, rebar size to cover depth and nonlinear crack analysis. These analysis results have good accordance with the experimental results of Williamson's work. This methodology can be applied to lifetime prediction procedure of reinforced concrete structures and also gives more reasonable results of concrete cover failure time estimation of reinforced concrete structures exposed to sea-water.

• Journal of the Korean institute of surface engineering
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• v.52 no.6
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• pp.364-370
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• 2019

Fe-Mn-Si-Ni-Cr-TiC alloys have a shape memory property, recovering initial shape by heating. With an aim to improve a durability and stability of building and infrastructure, this Fe-based shape memory alloy (FSMA) can be employed to reinforce concrete structure with creation of compressive residual stress. In this work, corrosion resistance of FSMA was compared with general rebar and S400 carbon steel to evaluate the stability in concrete environment. Potentiodynamic polarization test in de-ionized water, tap-water and 3.5 wt.% NaCl solution with variations of pH was used to compare the corrosion resistance. FSMA shows better corrosion resistance than rebar and S400 in tested solutions. However, Cl-containing solution is critical to significantly reduce the corrosion resistance of FSMA. Therefore, though FSMA can be a promising candidate to replace the rebar and S400 for the reinforcement of concrete structure, serious cautions are required in marine environments.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2005.05a
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• pp.161-164
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• 2005

According to the trend of tail building, it is essential to improve productivity in tall building construction. However, the study on that is insufficient until now. Therefore, the purpose of this study is to propose a new work process of efficient concrete structural fame work to improve productivity in tall building construction. The results of being applied proposed work process are that the 5day cycle time of concrete structural frame work is cut by 0.5day and the quantity of rebar to be demanded in concrete structural frame work is reduced.

• Journal of the Korea Institute of Building Construction
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• v.8 no.5
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• pp.67-73
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• 2008

Recent trends in construction towards larger scale and taller buildings are causing problems by ineffective existing management approach in construction industry have emerged. Delivering necessary materials and mobilizing the human resources and equipment In a timely manner to keep labor on schedule have become a critical issue to be addressed. In particular, many specialty contractors carrying out multiple projects have been experiencing difficulties mobilizing the manpower on time and in right places due to poor communication at each stage of labor supply, resulting in waste of valuable resources. Hence, it's imperative for the specialty contractors to obtain specific information on labor demand so as to set up a communication and labor management system to ensure the right human resources will be mobilized in the right place at the right time. The study therefore is aimed at developing an optimal human resources management system for specialty contractors performing multiple projects. To that end, the study is focused on rebar and concrete work. The outcome of the study is expected to help allocate the right human resources to the right place in a timely fashion, thereby achieving an effective workflow at construction sites.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.33 no.3
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• pp.317-331
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• 2023

Objectives: Construction workers are exposed to various hazardous substances simultaneously. However, little is known about the exposure hazards in construction industry. This study was aimed at identifying the risk of exposure hazards among construction workers. Methods: The expert survey (n=29) was conducted, including construction industry health managers (n=11) and work environment monitoring experts (n=18), on exposure probability, intensity and risk of hazardous substances by construction occupations Results: The exposure hazards of 30 construction occupations were identified and summarized through a literature review and expert survey. The most prevalent hazards were in order of noise, awkward posture, heat/cold, crystalline silica, cement/concrete dust, metal fumes, and volatile organic compounds. The hazards with highest risk score(over seven points) at construction occupations were noise(formwork carpenter, concrete finisher, rebar worker, demolition worker, driller/rock blaster), hazardous rays(welder), heat/cold (earthworks, formwork carpenter, rebar worker, concrete placer, scaffolder), awkward posture(bricklayer, caulker/tile setter, rebar worker) and heavy lifting(bricklayer, rebar worker). Among construction workers, the job types with the highest risk of exposure to carcinogens, and in which occupational cancer has been reported, were in order of stonemason, concrete finisher, rock blaster, welder, insulation installer, painter, scaffolder, plant worker and earthworks in order Conclusions: Systematic research and discussion on occupational disease among construction workers and its various hazardous factors are needed to establish job exposure matrix for facilitating standard for promptly processing the workers' compensation.

• Proceedings of the Korea Concrete Institute Conference
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• 1999.04a
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• pp.789-792
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• 1999

Reinforced concrete structures covered creek for road vehicle located in urban areas have been experiencing corrosion of concrete and reinforcing steel caused by $H_2S$ gases generated by anaerobic bacterial. H2S gases react with oxygen and water to form sulfuric acid ($H_2SO_4$). This acid chemically attacks concrete, and sulfate ions penetrate into the concrete, causing rebar corrosion. In this work, to determine the conditions of RC culvert boxes which were constructed in the 1970s, various tests were conducted, including carbonation depth, compressive strength, half-cell potential measurements, and XRD analyses. Results indicated that the concrete deterioration was caused by sulfate attack and rebar corrosion. This paper discusses the evaluation on the durability of reinforced concrete structures covered creek for road vehicle.

• Korean Journal of Construction Engineering and Management
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• v.8 no.1 s.35
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• pp.57-65
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• 2007

Rebar work is a labor intensive operation, and with labor shortage and high-wage era, the cost is rising, so re-bar manufacturing system in plant is adapted. However there remains a lot of problems. Although manufacturing system in plant, which greatly effects the building's safety, endurance, and construction time, is an important phase in construction, it holds serious problem of quality and productivity deterioration due to its characteristic of intensive-labor and maintaining of old work methods resulting in poor management, and costs increase. Therefor in this study to investigate current situation and problems of rebar work in plant and to find methods of betterment, a survey was conducted to factory engineers in 18 companies.