• Composites Research
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• v.35 no.4
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• pp.261-268
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• 2022

Ultra-high temperature ceramics (UHTC) such as ZrB₂, ZrC, HfB₂, HfC and TaC have been recently investigated for the application to hyper-sonic systems such as nose-cone, rocket nozzle and leading edge. In this paper, the recent research results about UHTC have been reviewed. Domestic and international research results about UHTC mainly during the last 5 years were briefly summarized. Also, the results of C³HARME project, which was one of the Horizon 2020 program in EU, to get over the problems of UHTC such as brittleness through the fabrication of ultra-high temperature ceramic matrix composites (UHTCMC) were briefly introduced.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.42 no.5
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• pp.681-688
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• 2022

According to a recent study, most construction companies in Korea do not manage risk effectively, and it is judged that the risk management system needs to be improved. In addition, most risk-related studies deal with risks from a macroscopic perspective, and there are few studies dealing with process risks at the project construction stage. Therefore, this study tried to suggest a risk response plan through analysis and classification of risk factors that may occur in retaining work among process risks. To this end, a workshop was held for risk experts to identify and analyze risks that may occur during the construction of retaining work for apartments. As a result of the study, it was expected that savings of KRW 4.97 billion would be possible in the 95 % confidence interval, and the maximum possible cost was reduced from KRW 15 billion to about KRW 10 billion. Based on the risk reduction ratio, it was found that risks that can be reduced without any special input cost, risks with large effects in response to risks, and risks with insignificant effects were found. Therefore, using the types and risk factors presented in this study as guides, it is expected that it will be helpful in successfully operating the project if an appropriate response strategy is prepared and systematically responded to the site conditions.

• Korean Journal of Construction Engineering and Management
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• v.18 no.6
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• pp.65-77
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• 2017

Recently, many Korean major construction companies are suffering from profit loss mainly due to a direct impact from delays in their overseas projects. In general, changes are inevitable in a large-scale project, and most of changes are directly linked to construction delay. Therefore, in the event that an extension of time is necessary due to a change, the contractor must manage the delay based on the condition of the contract to effectively manage risks from delay to the completion date. Thus it is important to understand delay protocol defined in the condition of the contract early in the project, but there have been few or no study to propose methodology or tool to support this effort. This paper presents a review on the project planning and controling practices of major Korean construction companies along with the issues on delay claims and disputes in mega-international projects and suggests a tool to assess delay risk in the condition of the contract. To propose a delay risk assessment model for international construction projects, major standard conditions of contract have been reviewed including FIDIC Red Book(1999), PSSCOC(2014) and SIA 9th Edition(2010). To reflect recent trend of major international owners, standard conditions which they are utilizing for their projects also have been reviewed including those of ARAMCO and QP. The model provides a categories of risks to be reviewed on the condition of the contract along with standard level of the risk which is common in the international standard form of the contracts. This study also performed a case study on an actual international project to confirm the effectiveness of proposed model to identify and respond to a delay risk of a project.

• Korean Journal of Construction Engineering and Management
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• v.20 no.2
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• pp.37-43
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• 2019

After the new standards for labor hours has been released, various problems come up in construction field, such as income reduction of employees, extension of construction period and increased construction cost. Although it is expected that the impact of the new standard on the construction industry is more worse than other industries form the view of productivity, not much works have been done to identify those impacts. Thus, this research proposes the standard construction processes, excavation cycle, and unit construction period for NATM tunnel project based on 'Construction Standard Production Rates.'The study also investigated the impact of reduced labor hours on the management of work crews, construction periods and costs of tunnel projects. The results showed that under the 52 labor hour standard, the construction periods for the excavation work and whole project was increased by 20% and 8.9%, respectively, but the construction costs for the excavation work and whole project was decreased by 1.4% and 0.6%, respectively.

• Korean Journal of Construction Engineering and Management
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• v.19 no.2
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• pp.50-60
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• 2018

Recently, modular construction method has been widely applied to projects with repetitive processes including dormitory, the residential facility, and the hotel construction due to reduced labor input and shortened construction schedule. Generally, about 40% of total on-site construction cost excluding unit installation cost, is put on exterior finishing work, and thus management of finishing work is deemed important in maintaining the targeted schedule and cost. Since limited equipment is shared so that subsequent activities are not affected while carrying out on-site installation and finishing work, lifting plan becomes more important for modular projects with greater portion of finishing work load. In this regard, tower crane operation plan may take the form of a single cycle or multiple cycles in which equipment efficiency can be affected. However, difficulties exist in evaluating alternatives to tower crane operation plans supporting unit installation and finishing work. Therefore, this study aims to evaluate the alternative of tower crane operation method according to the cyclic period setting in modular building site to determine the effect on T/C uptime and process by parameterizing lifting time for unit and exterior finishing material, lift cycle for unit and exterior finishing material and time required for finishing work. Accordingly, this study develops a simulation model that can increase the tower crane efficiency by controlling the work speed. An academic contribution of this study is to suggest a resource leveling method applying the concept of lifting cycle, and further is expected to be managerially used as a basis for an alternative evaluation of equipment plan.

• Journal of the Korea Institute of Building Construction
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• v.19 no.3
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• pp.263-272
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• 2019

Building Information Modeling (BIM) and modular construction are regarded as important technologies that have contributed to advancements in the construction industry. However, the utilization of BIM in current modular construction projects is limited; moreover, there are no specific guidelines pertaining the applications of BIM in modular construction projects. Therefore, this study aims to analyze the utilization of BIM for onsite construction planning in modular construction projects. First, a realistic BIM application was selected through literature review and expert interviews. Then, the construction plan of the modular projects was analyzed to classify the BIM application items into five different categories. The utilization of BIM in each category was then analyzed in terms of necessity and efficiency using a questionnaire. Finally, the BIM Utilization Index (BIM UI) was suggested based on the findings of the survey. As a results, the BIM UI for module point details, lifting plan, other installation details, site layout plan, and schedule plan was 0.811, 0.787, 0.770, 0.729, and 0.699, in the descending order of usability. In addition, through the findings of the study and interviews with experts, a case study for implementation of BIM in modular construction plan was conducted. The results of this study can be used as application guidelines for BIM in future modular construction projects.

• Proceedings of the Korean Institute Of Construction Engineering and Management
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• autumn
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• pp.598-601
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• 2003

As the scale of construction work is enlarged, complicated and diversified, construction information from the large number of construction sites is happened and reported to the head office. To control much information generated in construction sites simultaneously, the necessity of supporting system which can extract necessary information is increased. However, compare with large companies, medium-sized companies's organization of head office and management system is weak, so it's difficult to manage multi-projects. Among these site managements, resource management is an important management area. But, resource planning is based on experience and judgement and have not associated with schedule information. So when schedule if changed, the plan must be amended manually. This study investigates material-planning model for multi-project management which is connected with daily report system and scheduling software.

• Korean Journal of Construction Engineering and Management
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• v.2 no.4 s.8
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• pp.127-134
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• 2001

Effectiveness of Just in time managing system can be obtained by removing unexpected lead-time and maintaining consistency on the physical transportation of construction resource. Construction resource management is essential on checking on load data from production of shop to field, and it is based on building resource life cycle information. In this study, production, transportation, and assembly disciplines of concrete construction should real time communications exchanging information related to shop-field with each other, Establishing information support system is an important initial step for promoting active cooperations among these resource life cycle on data flow. To achieve this, on suitable using management point, we suggest a concrete construction control model.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.36 no.8
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• pp.865-871
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• 2012

Because of the increasing cost of oil and natural gas, energy production technologies using coal, including synthetic natural gas (SNG) and integrated gasification combined cycle (IGCC), have attracted attention because of the relatively low cost of coal. During the early stage of a project, the developer or project owner has many options with regard to the selection of a gasifier. In particular, from the viewpoint of feasibility, the gasifier is a key factor in the economic evaluation. This study compares the technical aspects of gasifiers for a real SNG production project in an early stage. A fixed-bed slagging gasifier, wet-type entrained gasifier, and dry-type entrained gasifier, all of which have specific advantages, can be used for the SNG production project. Base on a comparison of the process descriptions and performances of each gasifier, this study presents a selection guideline for a gasifier for an SNG production project that will be beneficial to project developers and EPC (Engineering, Procurement, Construction) contractors.

• Proceedings of the Korean Institute Of Construction Engineering and Management
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• 2006.11a
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• pp.264-267
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• 2006

Timely completion and a satisfied owner are the prime objectives of a construction project. The success to achieve these objectives of a project is fully depend on the working approaches (attitude) of a contractor company. Attitude is very difficult to be measured directly; therefore it must be inferred from assumed relationship with observable indicators. Commonly, behavior shown by a person or organization represents its attitude about things or persons or issues. The aim of this paper is to develop a framework for measuring attitude of contractors in an ongoing construction project. In this paper a set of key attitude indicators (KAIs) measured both objectively and subjectively have been developed through a field survey. The validity of the proposed KAIs is also tested by four case studies. The results of the study show that the KAIs stated in the paper can reasonably measure the attitude of contractors and can be helpful for the owners and project managers to control their projects effectively. This study also provides significant insights into developing a general and comprehensive base for further study.