• Proceedings of the Korean Geotechical Society Conference
• /
• 1990.10a
• /
• pp.69-86
• /
• 1990

This paper discusses how to protect the principal structures adjacent to subway tunnels being constructed by the shield or cut-and-cover methods by referring to some actual examples.

• Proceedings of the SAREK Conference
• /
• 2003.07a
• /
• pp.23-23
• /
• 2003

• Magazine of the Korea Concrete Institute
• /
• v.19 no.3
• /
• pp.50-54
• /
• 2007

• Corrosion Science and Technology
• /
• v.6 no.4
• /
• pp.186-192
• /
• 2007

Carbonation is one of the most important factors causing the corrosion of reinforcement concrete. Nevertheless, experimental studies on the concrete carbonation have not been carried out sufficiently because of the slow process of carbonation process. Therefore, this study adopts an experimental system exploiting a vacuum instrument that has been recently developed to accelerate carbonation instead of existing experimental system to conduct rapid carbonation tests on Portland cement and fly-ash cement concretes. Test results revealed that, compared to water-cement ratio of 40%, the carbonation depth increases from 103% to 138% for an increase of water-cement ratio from 45% to 60%. These results are larger than the carbonation depths obtained by mathematical model, and such difference is increasing with larger water-cement ratios. The results also indicated that larger fly-ash contents lead to sharp increase of the carbonation depth, which is in agreement with previous experimental researches. The adoption of the new accelerated carbonation test system enabled to shorten effectively the time required to produce experimental data compared to the existing carbonation test method. The experimental data obtained in this study together with ongoing acquisition of data using the new carbonation test method are expected to contribute in the understanding of the carbonation process of concrete structures in Korea.

• Advances in concrete construction
• /
• v.5 no.3
• /
• pp.241-255
• /
• 2017

Concrete is known to be the most used construction material worldwide. The environmental and economic aspects of Ordinary Portland Cement (OPC) containing concrete have led research studies to investigate the possibility of incorporating supplementary cementitious materials (SCMs) in concrete. Metakaolin (MK) is one SCM with high pozzolanic reactivity generated throughout the thermal activation of high purity kaolinite clay at a temperature ranging from $500^{\circ}C$ to $800^{\circ}C$. Although many studies have evaluated the effect of MK on mechanical properties of concrete and have reported positive effects, limited articles are considering the effect of MK on durability properties of concrete. Considering the lifetime assessment of concrete structures, the durability of concrete has become of particular interest recently. In the present work, the influences of MK on mechanical and durability properties of concrete mixtures are evaluated. Various experiments such as slump flow test, compressive strength, water permeability, freeze and thaw cycles, rapid chloride penetration and surface resistivity tests were carried out to determine mechanical and durability properties of concretes. Concretes made with the incorporation of MK revealed better mechanical and durability properties compared to control concretes due to combined pozzolanic reactivity and the filler effect of MK.

• KIEAE Journal
• /
• v.14 no.4
• /
• pp.61-68
• /
• 2014

Due to rapid climate changing and the need for energy conservation, environment friendly initiatives have emerged, and regulations to support establishment of green structures in construction have been legislated and enacted. In this study, the supporting of green build method act for rapid climate change and energy conservation. Using green build method, protecting surrounding ecosystem and developing green building continuously, I suggest alternative for protection of the environment. Identifies Envelope Design Elements among various construction Green Building Design Guidelines. Green buildings that we extract the Green Building envelope design from Design Guideline, select the object building through the green buildings examples of public institution relocation projects. Since then analyzes the planned schematic design and Green Envelope Design Elements and Green Building Certification(G-SEED). So, that future directions for planning correlation of Green Building and Design Guidelines about Green Design Elements Can be presented.

• Proceedings of the Korean Institute of Building Construction Conference
• /
• 2017.05a
• /
• pp.210-211
• /
• 2017

According to KS F 2560, water-reducing agents used when mixing concrete are to undergo quality evaluation testing slump, air contents, setting time, etc., when delivered from the admixture factory to the ready mixed concrete site. Yet in actual acceptance testing this could be substituted by the score report of the admixture company, in which a possibility of low reliability lies. Therefore this study sought to analyze whether by artificially changing the solid content rate of lignin- and naphthalene-based water-reducing agents and using a liquid densimeter evaluate the quality of the admixture. The results showed that the Type B liquid densimeter was most appropriate and 50cc the most appropriate capacity for the mass cylinder. Also, judging from the changes in density and pH according to the changes in solid content rate, it concludes that a rapid appraisal of the quality of lignin- and naphthalene-based water-reducing agents would be possible using a Type B liquid densimeter.

• Environmental Engineering Research
• /
• v.24 no.3
• /
• pp.397-403
• /
• 2019

Microcystis sp. is one of the most common harmful cyanobacteria that release toxic substances. Counting algal cells is often used for effective control of harmful algal blooms. However, Microcystis sp. is commonly observed as a colony, so counting individual cells is challenging, as it requires significant time and labor. It is urgent to develop an accurate, simple, and rapid method for counting algal cells for regulatory purposes, estimating the status of blooms, and practicing proper management of water resources. The flow cytometer and microscope (FlowCAM), which is a dynamic imaging particle analyzer, can provide a promising alternative for rapid and simple cell counting. However, there is no accurate method for counting individual cells within a Microcystis colony. Furthermore, cell counting based on two-dimensional images may yield inaccurate results and underestimate the number of algal cells in a colony. In this study, a three-dimensional cell counting approach using a novel model algorithm was developed for counting individual cells in a Microcystis colony using a FlowCAM. The developed model algorithm showed satisfactory performance for Microcystis sp. cell counting in water samples collected from two rivers, and can be used for algal management in fresh water systems.

• Proceedings of the Korean Institute of Building Construction Conference
• /
• 2021.11a
• /
• pp.204-205
• /
• 2021

In the event of a fire in a high-rise building, rapid evacuation through the stairwell is a very important factor in rapid evacuation. However, in the event of an actual fire, most of the occupants evacuate at the same time, resulting in a stay in the stairwell, reducing the evacuation speed. In Korea, conditions for buildings are created to evacuate quickly and safely while introducing performance-oriented designs to solve these problems, but there is no research data related to the evacuation speed due to joining in the event of vertical evacuation. Therefore, in this study, by analyzing the experiment conducted at W University in Japan, the density-speed relationship when staying in the staircase room was derived, and the regression equation was derived based on the results.

• Proceedings of the Korean Institute of Building Construction Conference
• /
• 2022.11a
• /
• pp.189-190
• /
• 2022

Power plants that produce electricity through thermal power plants mainly store coal in outdoor storage yards. In particular, coal is directly exposed to rainwater during rainfall, including torrential rain. There is no separate drainage facility in the outdoor coal yard, and coal is simply stored on the ground. Accordingly, during rainfall, coal dust flows down by rainwater, and a large amount of rainwater that is not drained overflows the outdoor coal yard, overflowing the surrounding facilities and causing environmental pollution. Therefore, in this study, a drainage system was developed for the rapid drainage of an outdoor coal mine, and the quality of the water was evaluated when rainwater mixed with drainage characteristics and coal dust was discharged through the drainage system.