• Earthquakes and Structures
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• v.9 no.6
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• pp.1193-1219
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• 2015

The purpose of this study is to evaluate the seismic performance of high-rise reinforced concrete (RC) box-type wall structures commonly used for most residential buildings in Korea. For this purpose, an analytical model was calibrated with the results of the earthquake simulation tests on a 1:5 scale 10-story distorted model. This calibrated model was then transformed to a true model. The performance of the true model in terms of the stiffness, strength, and damage distribution through inelastic energy dissipation was observed with reference to the earthquake simulation test results. The model showed high overstrength factors ranging from 3 to 4. The existence of slab in this box-type wall system changed the main resistance mode in the wall from bending moment to tension/compression coupled moment through membrane actions, and increased the overall resistance capacity by about 25~35%, in comparison with the common design practice of neglecting the slab's existence. The flexibility of foundation, which is also commonly neglected in the engineering design, contributes to 30~50% of the roof drift in the stiff direction containing many walls. The possibility of concrete spalling and reinforcement buckling and fracture under the maximum considered earthquake (MCE) in Korea appears to be very low when compared with the case of the 2010 Concepcion, Chile earthquake.

• Wind and Structures
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• v.18 no.1
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• pp.1-20
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• 2014

Modern design of long suspension bridges must satisfy at the same time spanning very long distances and limiting their response against several external loads, even if of high intensity. Structural Control, with the solutions it provides, can offer a reliable contribution to limit internal forces and deformations in structural elements when extreme events occur. This positive aspect is very interesting when the dimensions of the structure are large. Herein, an updated numerical model of an existing suspension bridge is developed in a commercial finite element work frame, starting from original data. This model is used to reevaluate an optimization procedure for a passive control strategy, already proven effective with a simplified model of the buffeting wind forces. Such optimization procedure, previously implemented with a quasi-steady model of the buffeting excitation, is here reevaluated adopting a more refined version of the wind-structure interaction forces in which wind actions are applied on the towers and the cables considering drag forces only. For the deck a more refined formulation, based on the use of indicial functions, is adopted to reflect coupling with the bridge orientation and motion. It is shown that there is no variation of the previously identified optimal passive configuration.

• Earthquakes and Structures
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• v.8 no.3
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• pp.591-617
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• 2015

Standards for seismic assessment and retrofitting of buildings provide deformation limit states for structural members and connections. However, in order to perform fully consistent performance-based seismic analyses of soil-structure systems; deformation limit states must also be available for foundations that are vulnerable to nonlinear actions. Because such limit states have never been established in the past, a laboratory testing program was conducted to study the rotational capacity of small-scale foundation models under combined axial load and moment. Fourteen displacement-controlled monotonic and cyclic tests were performed using a cohesionless soil contained in a $2.0{\times}2.0{\times}1.2m$ container box. It was found that the foundation models exhibited a stable hysteretic behavior for imposed rotations exceeding 0.06 rad and that the measured foundation moment capacity complied well with Meyerhof's equivalent width concept. Simplified code-based soil-structure analyses of an 8-story building under an array of strong ground motions were also conducted to preliminary evaluate the implication of finite rotational capacity of vulnerable foundations. It was found that for the same soil as that of the experimental program foundations would have a deformation capacity that far exceeds the imposed rotational demands under the lateral load resisting members so yielding of the soil may constitute a reliable source of energy dissipation for the system.

• Journal of Construction Engineering and Project Management
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• v.1 no.3
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• pp.45-51
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• 2011

During disaster response, prioritization of limited resources is one of the most important but challenging tasks. At the same time, it is imperative to timely provide to the rescuers with the adequate heavy equipment to facilitate lifesaving operations. However, supply of high demand equipment is usually insufficient during the initial phase of disaster response, challenging lifesaving operations. At the same time, resources outside of the disaster affected zone converge into the area to assist the response efforts, which is the effect of convergence that often made resource coordination challenging in large scale disasters. Meanwhile, the initial condition of the disaster is usually best known by civilians already at the area before and during impact of the disaster. The knowledge of the civilians is not always received and considered by the responding organizations. With the help of these civilians, critical information such as victim location, infrastructure damage, and risk condition could be better know before any response actions are taken. To efficiently collect information and utilize the converging resources, this paper proposes a geospatial information repository for initial condition reporting and update to guide search and rescue operations and deployment of equipment with safety considerations for the rescuers in large scale disaster response scenarios.

• Proceedings of the Korean Institute Of Construction Engineering and Management
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• 2007.11a
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• pp.425-430
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• 2007

Although waste management in construction industry has a significant impact on both economical and environmental issues, the current level of waste management performance in Korean construction is reported as relatively low. In this context, this study aimed to suggest the considerations for the improved construction waste management guideline, which leads to the effective waste management on a construction site. In order to reach this goal, the existing domestic construction waste management guidelines were analyzed based on the criteria of the environmental management procedure of ISO 14001. These considerations were described in three aspects such as "planning", "implementation and operation", and "checking and corrective actions".

• Journal of the Korean Society of Safety
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• v.26 no.5
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• pp.65-72
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• 2011

The use of waste concrete can resolve the environmental pollution and shortage of natural aggregate. However, recycled aggregate includes substantial amount of cement paste. So, these aggregates are more porous, and less resistant to mechanical actions than natural aggregates. So, recently, the new manufacture processes of high quality recycled aggregates were suggested such as heating and solving to acid liquid. But the method of solving to acid liquid is not economical and produces additional environmental pollution. In this paper, for the purpose of manufacture of high quality recycled aggregates, the heating processes was added to the existing process of recycled aggregates. To find the optimum process, the experiment was performed by using the method of statistical experiment design, and the heating temperatures(4 levels : 300, 450, 600 and $750^{\circ}C$) and heating times(4 levels : 5, 20, 40, 60 minute) were main experimental variables. By the test results, the optimum manufacturing condition of coarse recycled aggregate was $600^{\circ}C$ and 40 minute, and for the fine recycled aggregate, a little heating made a satisfaction to the KS standard quality code.

• Structural Monitoring and Maintenance
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• v.2 no.2
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• pp.145-164
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• 2015

Bridge scour is the predominant cause of overwater bridge failures in North America and around the world. Several sensing systems have been developed over the years to detect the extent of scour so that preventative actions can be performed in a timely manner. These sensing systems have drawbacks, such as signal inaccuracy and discontinuity, installation difficulty, and high cost. Therefore, attempts to develop more efficient monitoring schemes continue. In this study, the viability of using optical dissolved oxygen (DO) probes for monitoring scour depths was explored. DO levels are very low in streambed sediments, as compared to the standard level of oxygen in flowing water. Therefore, scour depths can be determined by installing sensors to monitor DO levels at various depths along the buried length of a bridge pier or abutment. The measured DO is negligible when a sensor is buried but would increase significantly once scour occurs and exposes the sensor to flowing water. A set of experiments was conducted in which four dissolved oxygen probes were embedded at different soil depths in the vicinity of a mock bridge pier inside a laboratory flume simulating scour conditions. The results confirmed that DO levels jumped drastically when sensors became exposed during scour hole evolution, thereby providing discrete measurements of the maximum scour depth. Moreover, the DO probes could detect any subsequent refilling of the scour hole through the deposition of sediments. The effect of soil permeability on the sensing response time was also investigated.

• Geomechanics and Engineering
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• v.11 no.6
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• pp.805-820
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• 2016

A fully coupled non-linear effective stress response finite difference (FD) model is built to survey the counter-intuitive recent findings on the reliance of pore water pressure ratio on foundation contact pressure. Two alternative design scenarios for a benchmark problem are explored and contrasted in the light of construction emission rates using the EFFC-DFI methodology. A strain-hardening effective stress plasticity model is adopted to simulate the dynamic loading. A combination of input motions, contact pressure, initial vertical total pressure and distance to foundation centreline are employed, as model variables, to further investigate the control of permanent and variable actions on the residual pore pressure ratio. The model is verified against the Ghosh and Madabhushi high acceleration field test database. The outputs of this work are aimed to improve the current computer-aided seismic foundation design that relies on ground's packing state and consistency. The results confirm that on seismic excitation of shallow foundations, the likelihood of effective stress loss is greater in deeper depths and across free field. For the benchmark problem, adopting a shallow foundation system instead of piled foundation benefitted in a 75% less emission rate, a marked proportion of which is owed to reduced materials and haulage carbon cost.

• Journal of Soil and Groundwater Environment
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• v.23 no.6
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• pp.1-8
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• 2018

In this study, formaldehyde and benzene were selected as the arbitrary chemicals in accidental leakage to environment, and their physicochemical and biological characteristics and toxicity were studied. Also, the fate of these chemicals in soil and groundwater was studied based on the results of previous studies. They can be released into the atmosphere as gas or vapor phase, which then can be photochemically degraded. Since they have relatively high water solubility, they are likely to have high mobility in water and soil. Volatilization of these chemicals from soil is affected by the soil moisture content. Biodegradation of formaldehyde and benzene is one of the important pathways as well. Therefore, it is necessary to study the environmental impacts of leakage accidents of flammable chemicals such as formaldehyde and benzene. Further research on the fate of flammable chemicals in the environment is needed to take appropriate response actions to leakage accidents of flammable chemicals, and this will contribute to the development of practical guidelines to cope with leakage accidents.

• The Journal of Asian Finance, Economics and Business
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• v.10 no.2
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• pp.281-300
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• 2023

Recently, the call for better accountability and social responsibility from corporations has been regularly voiced, both in the academic literature and in public discussions. This poses a challenge to the existing literature in understanding consumption behaviors to direct them toward sustainable development. This study investigates the purchase intention of Gen Z consumers in Vietnam with green packaging products. Data were collected from 914 respondents by online questionnaire and then analyzed using OLS. The results suggest the significant influence of customers' income and packaging in driving customers' intention to use environmentally-friendly products. Specifically, consumers in a higher income class participate more actively in green purchases. However, problems associated with inadequate packaging are also illustrated, resulting in the poor perception of green messages and poor practice of ecological actions. Besides, subjective norms and green trust are found to be adversely related to green consumer intention. In addition, gender disparity in green behavior is reported, where female consumers show a higher tendency to ecological consumption than their male counterparts. Other demographic factors are also included in the model as control variables, which are age, education, price, environmental literacy, environmental concern, and psychological awareness, but they do not have a significant impact on green purchase intention.