• Journal of Korean Society of Steel Construction
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• v.11 no.4 s.41
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• pp.409-416
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• 1999

The fatigue crack growth analysis based on the fracture mechanics is useful to the estimation of the fatigue life on welded structures under cyclic loading. The analysis procedure in fatigue crack growth under uniform axial loading is applicable to bending fatigue problem as well. The intent of the present study is to show the procedure for calculating the fatigue crack propagation lifetimes of deckplates under bending stress and to explain the crack growth rates for the two dimensional crack problems. It is shown that the fatigue crack grows at a decreasing rate and the fatigue life depends on the initial crack length and the crack shape. The numerically predicted crack growth agree with the experimental data.

• Journal of Korean Society of Steel Construction
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• v.8 no.4 s.29
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• pp.133-133
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• 1996

Application of the relationship $da/dN=C({\Delta}K)^{m}$ is effective in the analysis of fatigue crack growth life. The values of material constant C and m have great influences on the predicted fatigue life and the relationship between fatigue crack growth rate(da/dN) and stress intensity factor range(${\Delta}K$) is effective in fatigue crack growth behavior. In this paper, fatigue crack growth behavior of the welded joints in HT60 grade TMCP(Thermo Machanical Control Process) steel have been studied. To evalute the fatigue crack growth rates of HT60 grade TMCP steel, fatigue test was performed by base metal(BM), heat affected zone(HAZ) and weld metal(WM) in TMCP steel at room temperature. We determined the relationship of $da/dN-{\Delta}K$ by correlation between C and m obtained from the Paris-Erdogan power law data supplied HT60 grade TMCP steel. The obtained results from this study indicate that fatigue crack growth rate of TMCP steel is not influenced by softening effect which occurs in the HAZ when high heat input weld is carried out. Softening effects, which affect fatigue properties. are shown that it is not affected to the fatigue growth rates significantly.

• Journal of Environmental Science International
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• v.32 no.3
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• pp.161-171
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• 2023

The present study evaluated growth factors affecting oak community plantations through literature review and a field survey. Specifically, 41 related literature sources were analyzed and field surveys were conducted to collect growth data. Previous studies were analyzed to identify variables with high frequency of use. The frequency of use was in the order of tree size > environment > planting density > forest age. Analysis of factors impacting height and diameter growth revealed that the growth rate of species other than Quercus variabilis was negative in the field survey. This may be because of differences between the actual trees planted and specifications in the construction drawings, which may be attributed to the site conditions and decisions made by the project subject during construction. Furthermore, simple linear regression analysis was conducted with time, height at planting, density, and species code as the independent variables and growth rate as the dependent variable. A strong positive linear correlation was noted between height and diameter. This work builds a foundation for developing a forest restoration model and simulation program based on a regression model derived from the four variables tested.

• Journal of Construction Engineering and Project Management
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• v.4 no.2
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• pp.12-22
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• 2014

Over the last decade, Saudi Arabia has experienced significant economic increases as evidenced by the 30% growth in its gross domestic product; furthermore, the construction industry has increased 10% in the same time period. Due to this significant growth, the construction industry is encountering issues related to construction quality resulting in significant waste and associated environmental impacts. In this research, we applied our previously developed framework that integrates three different methods-Lean, Green, and Six-sigma - to a residential construction complex in Saudi Arabia. Our aim of this case study was to explore the application of the framework in practice to glean quantitative results and further validate the framework. In the case study, we used the developed framework to identify a significant issue related to quality and delays - final completion of 53 residential units was delayed because of failed exterior buildings surfaces. We then used the framework to define the causes behind the defects via a field investigation of the 53 units. Of the defect, construction execution was responsible for 43% of the defect, 31% untrained workers, 19% unfavorable construction weather condition, with 7% accounting for other issues. A procedure was developed in concert with the construction manager and overall developer reducing the amount of rework and waste causes revealed by the field examination and the framework. Although two steps were added to the original construction process to overcome waste causes, still save a lot of resources and reduces environmental impact. In summary, we found that the Lean, Green, Six-sigma framework increased productivity, quality, and reduced waste.

• Korean Journal of Construction Engineering and Management
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• v.14 no.5
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• pp.103-112
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• 2013

After 1990s, the influence of construction industry has been decreased on national economy and construction business condition has been changed on economic recession and boom repeatedly. Larger fluctuation of business condition makes a forecast of it to be more difficult. Uncertainty in business prediction results in damages on construction companies and stakeholders. Therefore, study on forecasting a construction business is very important. This study suggests the Construction Industry Production Index(CIPI) to predict a construction business in consider of temperature effects. The results show that construction business is much influenced by temperature effects certainly and GDP. With the CBFM, this study examines CIPI for 2013 with two scenarios: 1)with GDP growth rate of 3.5% 2)with GDP growth rate of 2.4%. Thus, CIPI would be used as the economic state index to display the construction business conditions. Also, CIPI will be utilized as basic methodology in the impact of climate change in the construction industry.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2012.05a
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• pp.133-135
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• 2012

The Fire growth rate(kW/s²) is significant impact on initial fire behavior in fire safety design of buildings. As a result of domestic existing combustibles, this study analyzed considering matters in techniques for calculating caloric values, and then made an investigation sheet. By utilizing written combustion sheets, the study could suggest a standard model at common houses and dense ones after getting caloric value information in dense ones. As a result, fire growth rate is experiment 1(0.01), experiment 2(0.0048), FDS(0.0072), MATSUYAMA equation(0.0144).

• Korean Journal of Construction Engineering and Management
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• v.13 no.5
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• pp.125-134
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• 2012

In the construction industry, "Green" is emerging as a keyword of new growth engine. Since green construction competitiveness is essential for contractors' survival and growth, it is important to understand what constitutes green construction competitiveness. The objective of the study is to identify elements of green construction competitiveness and to discuss relationships between their importance and current level based on the Gap analysis. A better understanding of the elements of green construction competitiveness assists contractors in formulating green strategies. It also provides insight into what motivates contractors in establishing related policies and regulations. The study identifies that in general there exists a gap between the importance and current level of green construction competitiveness. It also demonstrates that CEO' competence shows a less gap between the importance and current level but firms' competence is an area of weakness. Finally a substantial gap is observed in the field of green R&D strategies and sub-contracting partners.

• Journal of Korea Planning Association
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• v.54 no.6
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• pp.27-42
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• 2019

The purpose of this study is to identify the spatial characteristics of the parcels in which building construction occurred. In recent, urban development patterns in Korea have been shifting from the past. Small-scale development at parcel level is becoming more important in accordance with individual location needs in the low-growth era unlike public lead large-scale urban development in the rapid growth period. Therefore, it is necessary to study the spatial characteristics of the parcels where small-scale development takes place for future urban development management. This study used the chi square independence test, t-test and ANOVA (analysis of variance) to identify the spatial characteristics. The results of the study show that there is a spatial characteristics difference not only between building construction and non-building construction parcels, but also by type of building construction. The parcel where the building construction occurred have a higher proportion in detached house, major commercial districts, district unit planning areas, and commercial areas. In addition, it is caused by parcels, which are large scale and economically valuable, and are influenced by traffic factors such as urban centers and subway accessibility. As a result of each type of building construction, the parcels where the building use change occurred have spatial characteristic difference compared to other building construction, while the spatial characteristics are similar between the new construction/extension and new construction/extension with change of use. Based on this results, it will be possible to identify areas with high demand for small-scale development in the future and to utilize them for planning management of urban development. Furthermore, it will be possible to manage development demand by type of building construction, and to prepare differentiated plans considering the appropriateness of development plan, availability of infrastructure, and harmony with surrounding environment.

• International Journal of Safety
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• v.4 no.1
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• pp.23-26
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• 2005

In spite of the rapid economic growth in Korea, safety cultures in construction industry have not much improved during last ten years. When it is compared to other developed countries of safety, accident rate of Korean construction sites shows bleak figures. This study compares the safety figures of Korea with the UK figures in order to find out what is needed for the safety of the construction sites in Korea. By comparing occupations, age groups, kind of accident, and agent, this study found several differences and similarities, and derived the directions for better safety management.

• Journal of Korean Society on Water Environment
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• v.29 no.4
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• pp.551-558
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• 2013

The feasibility of water supply as in-stream flow for Mangwall stream was analyzed in terms of water quality and cultivation periphyton using two different types of water resources (e.g., surface water and bank filtration from Han River basin) and three different types of media (e.g., tile, concrete and pebble). The concentrations of organic and inorganic contaminants from the bank filtration were lower than those from surface water by 17.5 - 55.0%. Using water samples collected from Mangwall stream, surface water, and bank filtration, chlorophyll-a, phaeopigment, and growth rate of periphyton were investigated. During 30 day incubation for each water sample, it was observed that filamentous cyanobacteria, Oscillatoriaceae, accounted for 98%, and water velocity of 5 cm/s was optimum for the in situ filamentous cyanobacteria growth. Also, it was deducted for water velocity and chl-a to have an inverse correlation. Meanwhile, the greater the specific surface area of media, the higher the concentration of chl-a. From these results, both water velocity and specific surface area of media should be considered as an combined parameter to deter the growth of filamentous cyanobacteria.