• Land and Housing Review
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• v.7 no.4
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• pp.165-175
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• 2016

The Sejong Metropolitan Autonomous City is launched on July 1, 2012, and Phase 1 of the Multifunctional Administrative City Construction Project was completed in late 2015. Therefore, it is necessary through the results of the first phase of the project to check whether Sejong city can achieve the target population and number of households by 2030 and to use to determine the number and type of housing to be supplied next. Based on the presented results of the Phase 1 project period, this study estimate the population and number of households in 2030. For forecasting future population the population growth rate seen in the future of Sejong City's population forecast published by the National Statistical Office and the performance against plans Step 1 were used for forecasting future population. The results of analysis showed that the Multi-functional Administrative City is difficult to attract five hundred thousand people and two hundred thousand houses. In the analysis of households by type The Multi-functional Administrative City is The large proportion of 3-4 person households and high-income earners and Homeowners. But it increased the proportion of households with 1-2 people and rent house of the city grows in size and it is likely to change the level of income. Therefore, it is determined that there is a need to reflect these elements in next housing.

• Journal of the Korea institute for structural maintenance and inspection
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• v.15 no.6
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• pp.92-99
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• 2011

Ultra High Performance Concrete(UHPC) is a superior structural material with high strength and durability. Construction of light and slim structures is realized to apply this expectable new materials in practice. This research is a part of the project to develop UHPC precast deck system for hybrid cable stayed bridge. The main object of this study is to investigate behavior of the lap-spliced reinforced connection in UHPC. The major parameter considered in experimental plan was lap-spliced length. The 4-points bending test for 12 specimens were conducted to verify the effect of considered parameters. Test results show that the minimum value of lap spliced length of 300mm which specified in current korea high bridge design code was very conservative for UHPC precast deck system.

• Computers and Concrete
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• v.24 no.5
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• pp.459-468
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• 2019

The stability and safety of concrete plug structure of diversion tunnel is crucial for the impoundment of upstream reservoir in hydropower projects. The ongoing Wudongde hydropower plant in China plans to adopt straight column plugs and curved column plugs to replace the traditional expanded wedge-shaped plugs. The performance of the proposed new plug structures under high water head is then a critical issue and attracts the attentions of engineers. This paper firstly studied the joint bearing mechanism of plug and surrounding rock mass and found that the quality and mechanical properties of the interfaces among plug concrete, shotcrete, and surrounding rock mass play a key role in the performance of plug structures. By performing geophysical and mechanical experiments, the contact state and the mechanical parameters of the interfaces were analyzed in detail and provide numerical analysis with rational input parameters. The safety evaluation is carried out through numerical calculation of plug stability under both construction and operation period. The results indicate that the allowable water head acting on columnar plugs is 3.1 to 7.4 times of the designed water head. So the stability of the new plug structure meets the design code requirement. Based on above findings, it is concluded that for the studied project, it is feasible to adopt columnar plugs to replace the traditional expanded wedge-shaped plugs. It is hoped that this study can provide reference for other projects with similar engineering background and problems.

• Steel and Composite Structures
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• v.41 no.5
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• pp.681-695
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• 2021

Many existing transmission or communication towers designed several decades ago have undergone nonreversible performance degradation, making it hardly meet the additional requirements from upgrades in wind load design codes and extra services of electricity and communication. Therefore, a new-type non-destructive reinforcement method was proposed to reduce the on-site operation of drilling and welding for improving the quality and efficiency of reinforcement. Six built-up steel angle members were tested under compression to examine the reinforcement performance. Subsequently, the cyclic loading test was conducted on a pair of steel angle tower sub-structures to investigate the reinforcement effect, and a simplified prediction method was finally established for calculating the buckling bearing capacity of those new-type retrofitted built-up steel angles. The results indicates that: no apparent difference exists in the initial stiffness for the built-up specimens compared to the unreinforced steel angles; retrofitting the steel angles by single-bolt clamps can guarantee a relatively reasonable reinforcement effect and is suggested for the reduced additional weight and higher construction efficiency; for the substructure test, the latticed substructure retrofitted by the proposed reinforcement method significantly improves the lateral stiffness, the non-deformability and energy dissipation capacity; moreover, an apparent pinching behavior exists in the hysteretic loops, and there is no obvious yield plateau in the skeleton curves; finally, the accuracy validation result indicates that the proposed theoretical model achieves a reasonable agreement with the test results. Accordingly, this study can provide valuable references for the design and application of the non-destructive upgrading project of steel angle towers.

• Korean Journal of Construction Engineering and Management
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• v.14 no.5
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• pp.84-91
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• 2013

In 2012, Korean overseas construction market has achieved 64.9 billion dollars of contract order and its amount has increased since the mid 2000's. However, importance of qualitative growth based on profitability as well as quantitative growth is also emphasized. This study analyzed overseas plant project's subcontract process management which is closely related to cost management as one of the qualitative growth methods. In order to select major subcontract processes, extensive literature review and focus group interview(FGI) were implemented and then professionals with years of experience in the overseas plant projects were participated in the questionnaire survey. The collected data were analyzed by Benefit-Structure Analysis(BSA) model. The findings of this study include: (1) the seven and six subcontract processes are positioned in the area of importance control factor and in the area of maintenance/control factor, respectively; (2) administration capability attainment is needed for the six subcontract processes in the area of importance control factor and sustainable management system is required for the processes in the maintenance/control factor area. The further research will identify key subcontract processes to be managed for overseas plant projects by Korean EPC contractors based on the findings of this research.

• Journal of the Korean Wood Science and Technology
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• v.43 no.6
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• pp.876-883
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• 2015

Han-green project, which pursues Korean style post and beam timber house with traditional construction technique of Han-ok, has been carried out in KFRI (Korea Forest Research Institute) since 2006. Recently, the improvement of its building energy performance was studied with energy-saving elements. This study was conducted to provide the insulation details of building envelopes in a post-beam timber house for recent enhanced insulation standards and following effect on building energy performance. The level of thermal transmittance (U-value) values of building envelopes was composed of two stages: present Korean insulation standards and passive house. To evaluate building energy performance, the building airtightness values of two stages was ACH50 = $3.0h^{-1}$ for common domestic timber house constructed recently, and ACH50 = $0.6h^{-1}$ for passive house. Consequently, four cases of the building energy performance according to the combination of U-value with airtightness were evaluated. The test house for evaluation was located in Seoul and its energy performance was evaluated with CE3 commercial building energy simulation program. The result showed that enhanced insulation from level I to II reduced $14kWh/(m^2{\cdot}a)$ of annual heating energy demand regardless of airtightness.

• Journal of Venture Innovation
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• v.7 no.1
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• pp.151-166
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• 2024

The global economic growth rate has been slowed due to changes in the economic and social environment related to the recent trends in the construction market and construction industry, prolonged inflation, intense tensions among countries, and increased interest rates. Since the workers in the construction industry, due to the nature of the industry, move to another site after the completion of an awarded project rather than staying for a long time while performing work at one workplace, various issues are brought out such as poor working environment resulting from unfairness in construction contracts, aging of workers, their anxiety, and job instability. The previous studies on the turnover intention of construction industry workers mainly dealt with external aspects such as leadership, job embeddedness, and organizational citizenship behavior, while the psychological impact was overlooked. The purpose of this study was to develop a measure to reduce or alleviate turnover intention of construction industry workers by verifying empirically the relationship among psychological capital, organizational commitment, and turnover intention among them. For the purpose, whether psychological capital influences organizational commitment and turnover intention, the impact of organizational commitment on turnover intention, and whether organizational commitment has a mediating effect in the relationship between psychological capital and turnover intention, among 310 construction industry workers in the metropolitan area. The results are as follows: First, hope and self-efficacy were found to have a negative (-) effect on turnover intention, while resilience and optimism from psychological capital did not have a significant effect. Second, hope, resilience, and optimism from psychological capital were found to have a positive (+) effect on organizational commitment, while self-efficacy from psychological capital had no significant effect. Third, organizational commitment was found to have a significant mediating effect on the relationship between hope from psychological capital and turnover intention. The results of this study showed that, in construction industry workers, psychological capital affects turnover intention through the mediating effect of organizational commitment. While previous studies mainly considered external influences on the turnover intention of construction industry workers, this study has academic implications in that it sought to strengthen organizational commitment and alleviate turnover intention by approaching psychological aspects. As a practical implication, it was found that higher self-efficacy and hope for work in the organization, from psychological capital, in the construction industry workers were found to lower turnover intention through job performance in a psychologically stable state. It is considered, therefore, that various systems, including job autonomy and flexible work, should be established to improve self-efficacy and hope.

• Journal of Korean Tunnelling and Underground Space Association
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• v.26 no.2
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• pp.91-111
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• 2024

Most of utility cable tunnels are constructed utilizing shield TBM as part of the underground transmission line project. The TBM chamber is the only space inside the tunnel that encounters rock and soil, and is the place with the highest frequency of accident exposure, such as collapse and collision accidents. Since there is currently no way to measure the disc cutter wear from outside the chamber, frequent inspection by workers is essential. Accordingly, in this study, in order to prevent safety accidents inside the TBM chamber and expect the effect of shortening the construction period by reducing the number of chamber openings, the concept of disk cutter wear measurement technology was established and a prototype was produced. By considering prior technology and determining that magnetic sensors are most suitable for the excavation environment, wear measurement sensor package were developed integrating magnetic sensors, wireless communication modules, power supply, external casing, and monitoring systems. To verify the performance of the prototype in an actual excavation environment, a full-scale tunnelling test was performed using a 3.6 m EPB shield TBM. Based on the full-scale tests, five prototypes were operated normally among eight prototypes. It was analyzed that sensor measurement, wireless communication, and durability performance were secured within a maximum thrust of 3,000 kN and a rotation speed of 1.5 RPM.

• Journal of the Korean GEO-environmental Society
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• v.19 no.4
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• pp.27-32
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• 2018

There were many ground excavation projects from past to present to make effective use of the limited land. And it is very important to predict the ground behavior depending on construction stage for ground excavation. Excavation of the ground involves changes in the stress and displacement of the ground around the excavated surface. Thus it affects the stability of the adjacent structure as well as the excavated surface. Therefore, it is very important to predict the ground behavior and stability of adjacent structure. And nowadays, numerical analysis methods are most often used to predict the effects of ground excavation. Recent, improvements of numerical analysis programs, along with improved computer performance, have helped solve complicated ground problems. However, except some specialized numerical analysis, most numerical analysis often predicts larger excavation floor displacement than field data due to adopt the Mohr-Coulomb analysis model. As a result, it raise the problem that increasing the amount of support on ground and structure. In this study, ground behavior analysis depending on analysis model (Mohr-Coulomb, Duncan-Chang, Modified Mohr-Coulomb and Hardening Soil model) has been carried out through the numerical analysis. When numerical analysis is carried out, this study is expected to be used as a basic data for adopting a suitable analysis model in various ground excavation project.

• Korean Journal of Construction Engineering and Management
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• v.13 no.5
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• pp.3-11
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• 2012

The most of domestic bridge has an used life under 30 years, Future maintenance budgets can be expected to increase. However, because of bridge maintenance budgets are limited, demand for asset management being performed to achieve required performance within available budget is increasing. To perform effective asset management of bridges should be made the best use of information to occur in all phase of construction project. Therefore, the development of system and DB is required to support asset management by effective information management. The objective of this study is the development of the BIM-based bridge asset management model. Through previous research survey, BIM capabilities and asset management components were established and mutual linkages were examined. Bridge asset management model was composed of alternate assessment model. In addition, BIM-based asset management model was performed case studies to verify feasibility and applicability. The proposed model can be applied to a current bridge maintenance procedures and supported to perform effective bridge maintenance tasks within a limited budget.