• Journal of the Korean Ceramic Society
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• v.53 no.1
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• pp.116-121
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• 2016

The amount of carbon dioxide ($CO_2$) released while producing building materials is substantial and has been targeted as a leading contributor to global climate change. One of the most typical methods of reducing $CO_2$ in building materials is the addition of slag and fly ash, like pozzolan material another method is to reduce $CO_2$ production by developing carbon negative cement. MgO-based cement from the low-temperature calcination of magnesite required less energy and emitted less $CO_2$ than the manufacturing of Portland cements. It is also believed that adding reactive MgO to Portland-pozzolan cements can improve their performance and also increase their capacity to absorb atmospheric $CO_2$. In this study, basic research on magnesia cement using $MgCO_3$ and magnesium silicate ore (serpentine) as the main starting materials, as well as blast furnace slag for the mineral admixture, was carried out for industrial waste material recycling. In order to increase the overall hydration activity, $MgCl_2$ was also added. In the case of the addition of $MgCl_2$as accelerating admixture, there was a promoting effect on the compressive strength. This was found to be due to the production of needle-like dense Mg-Cl hydrates. Mgnesia cement has a high viscosity due to its high specific surface area therefore, when the PC-based dispersing agent was added at a level of more than 1.0%, it had the effect of improving fluidity. In particular, the addition of $MgCl_2$ in magnesia cement using $MgCO_3$and magnesium silicate ore (serpentine) as main starting materials led to a lower expansion ratio and an increase in the freeze-thaw resistance finally, the addition of $MgCl_2$ as accelerating admixture led to good overall durability.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2010.05a
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• pp.243-246
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• 2010

Recently, global warming problem is a major issue in international community. The carbon dioxide ($CO_2$) emissions in the construction industry is one of the main factors causing a global warming problem. Accordingly, various researches on $CO_2$ emissions caused by the construction industry is needed and construction methods which is low $CO_2$ emissions should be developed. In this study, $CO_2$emission cost is compared with roof waterproofing types in construction phase. As a result, the $CO_2$ emission costs of asphalt waterproofing is the highest. This research is to provide basic information for selecting appropriate construction methods in aspect of low $CO_2$ emission cost.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2003.11a
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• pp.27-31
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• 2003

To maintain serviceability of concrete structure more than proper it is necessary not only predict service life through periodical monitor but also need monitoring system to recognize optimal time and method for repair. Recently, CPGFRP, replacing some GFRP with CF, is developed and used for monitoring concrete fraction. But dramatic resistance change of CPGFRP is showed below 0.5% strain and it is not small strain in terms of monitoring micro crack in concrete. In other word, monitoring with CF is not suitable in low stress hut hight stress. In this study, we accessed applicable possibility and reliability of CPGFRP composite as monitoring sense that is proved very sensitive to stress through domestic and oversea previous study. CPGFRP composite plays a role in specimen like steel and increases flexural strength. CPGFRP composite shows resistance increasement in micro crack. In particular, CPUFRP is more sensitive than strangage in low stress. Resistance change ratio curve is very similar to strain curve so sensitivity and reliability is very excellent to monitor concrete fracture.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2003.05a
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• pp.27-31
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• 2003

To maintain serviceability of concrete structure more than proper it is necessary not only predict service life through periodical monitor but also need monitoring system to recognize optimal time and method for repair. Recently, CPGFRP, replacing some GFRP with CF, is developed and used for monitoring concrete fraction. But dramatic resistance change of CPGFRP is showed below 0.5％ strain and it is not small strain in terms of monitoring micro crack in concrete. In other word, monitoring with CF is not suitable in low stress but hight stress. In this study, we accessed applicable possibility and reliability of CPGFRP composite as monitoring sense that is proved very sensitive to stress through domestic and oversea previous study. CPGFRP composite plays a role in specimen like steel and increases flexural strength. CPGFRP composite shows resistance increasement in micro crack. In particular, CPGFRP is more sensitive than strangage in low stress. Resistance change ratio curve is very similar to strain curve so sensitivity and reliability is very excellent to monitor concrete fracture.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2023.05a
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• pp.115-116
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• 2023

This study aims to investigate and improve the carbon dioxide sequestration capability and the mechanical properties of non-hydraulic low calcium silicate cement especially designed for CO₂ reaction and ordinary Portland cement subjected to the carbonation curing facilitating pH swing method. Nitric acid (HNO₃) was utilized as an liquid for the mixing of cement paste to enhance the initial dissolution of Ca ions from the cements by promoting low pH environment and prevent the direct precipitation of Ca with the anion, owing to the high solubility of Ca(NO₃)₂ in water. The results presented that the higher the concentration of HNO₃, the higher the compressive strength and CO₂ sequestration (until 0.1 M). Ca dissolution caused by the harsh acid attack onto the anhydrous cement particle lead to the higher carbonation reaction degree, forming abundant CaCO₃ crystals after the reaction. However, cement paste mixed with excessively high concentration of HNO₃ presented deterioration due to the too harsh pH environment and abundant NO₃- ions which are known to retard the reaction of cement.

• 한국태양에너지학회:학술대회논문집
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• 2011.04a
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• pp.179-184
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• 2011

The development of new energy has attracted consideration attention due to the high oil price and environmental problems. In advanced country, they have tried to carry out a long range plan for energy. We need to develop new energy for Low Carbon Green Growth in Korea. The building is 30% among ratio of energy consumption in Korea. And in the past, heating energy was high ratio for energy using at home. But recently, the demand for cooling energy keeps growing due to rising average temperature on the earth and improvement of life quality. In this situation, the energy of lake water and ocean water has studied to utilize in advanced country because of low temperature at underwater. But the study for deep water is still a lot left to do. In this study, we analyzed district cooling system and the present condition. Analyzing the deep lake water cooling system in Toronto, we found an application of district cooling system using deep ocean water. Deep lake water uses heat source for district cooling and water source for city in Toronto. So reducing the initial cost, this city had economic effect. When DLWC was applied at existing building, the heat exchanger was installed instead of cooling tower and refrigerator. And the heat exchanger used to connect main pipe with cool water on city. System using deep ocean water can be applied as a similar way to supply cool water from lake to building.

• Journal of the Korean Recycled Construction Resources Institute
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• v.10 no.3
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• pp.227-234
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• 2022

In this study, the rheological properties of cement paste composites applied with carbon-based nano-materials were experimental analyzed. Flow table and rheological properties, compressive strength were measured in the cement paste using graphene oxide asqueous solution and carbon nanotube aqueous solution. When carbon nano-materials was mixed in an aqueous solution, flow decreased and plastic viscosity and shear stress were increased. In particular, graphene oxide rapidly increased the plastic viscosity and shear stress. In the case of carbon nanotube aqueous solution, when less than 0.2 % was mixed, the increase rate was low compared to graphene oxide. This is because the specific surface area of graphene, which is in the form of a plate, is large. The compressive strength showed a small amount in strength increase when graphene mix, and CNT had a strength about 112 % of OPC. Carbon-based nanomaterials, is considered that CNT are suitable more to be used construction materials. However, extra studies on the surfactant to be used for mixing proportion and dispersion will be needed.

• Resources Recycling
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• v.24 no.2
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• pp.13-22
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• 2015

$CO_2$ emitted from building materials and construction materials industry reaches about 67 million tons, which occupy about 30 % of $CO_2$ emitted from the construction field. Controls on the use of consumed fossil fuels and reduction of emission gases are essential for the reduction of $CO_2$ in the construction area as we reduce the second and third curing to emit $CO_2$ in the construction materials industry. Accordingly, this study applied the low energy curing admixture (hereinafter "LA") to the extruded panels to observe the physical properties, depending on the mixing amount of fiber, type of fiber and mixing ratio of fiber. The type of fiber did not appear to be a main factor to affect strength, while the LA mixing ratio and mixing amount of fiber appeared to be major factors to affect strength. Especially, the highest strength was developed when the LA mixing ratio was 40%, whereas the test object with the mixing ratio of 50% resulted in the decrease of strength. In addition, it appeared that the mixing ratio of fiber greatly affected flexural strength and strength increased as the mixing ratio increased.

• JSTS:Journal of Semiconductor Technology and Science
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• v.14 no.2
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• pp.153-162
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• 2014

We show that carbon nanotube sensors with gold particles on the single-walled carbon nanotube (SWNT) network operate as Schottky barrier transistors, in which transistor action occurs primarily by varying the resistance of Au-SWNT junction rather than the channel conductance modulation. Transistor characteristics are calculated for the statistically simplified geometries, and the sensing mechanisms are analyzed by comparing the simulation results of the MOSFET model and Schottky junction model with the experimental data. We demonstrated that the semiconductor MOSFET effect cannot explain the experimental phenomena such as the very low limit of detection (LOD) and the logarithmic dependence of sensitivity to the DNA concentration. By building an asymmetric concentric-electrode model which consists of serially-connected segments of CNTFETs and Schottky diodes, we found that for a proper explanation of the experimental data, the work function shifts should be ~ 0.1 eV for 100 pM DNA concentration and ~ 0.4 eV for $100{\mu}M$.

• Journal of the Economic Geographical Society of Korea
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• v.24 no.4
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• pp.400-410
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• 2021

This study analyzed the determinants of carbon dioxide emissions through the expanded STIRPAT model using panel data from 16 metropolitan cities and provinces in Korea from 2000 to 2019. After testing cross-sectional dependence and coefficient heterogeneity of panel data, we performed analysis using MG, CCEMG, and AMG estimation methods reflected these characteristics. The results of analysis using the AMG estimation method are as follows. The coefficients of income, population, and energy intensity were statistically significant with a positive sign, but urbanization was statistically insignificant. Reduction of carbon dioxide emissions in Korea can be achieved through an increase in energy efficiency and sustainable economic growth. It is necessary to establish a policy that can contribute to sustainable economic growth by inducing productivity improvement through technology innovation reducing carbon dioxide emissions in the long-term as well as building a low-carbon society through active development of carbon dioxide reduction technology.