• Journal of the Korean Institute of Landscape Architecture
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• v.28 no.5
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• pp.48-57
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• 2000

This paper is dealing with the fundamental properties of planting concrete, replacing the existing cover concrete on the roof of a building. This study is to find out the physical characteristics of the planting concrete and rearing characteristics of the grass throughout the modeling experimental materials. As the results of the experiment, the physical properties of planting concrete show the following results; when the paste to aggregate ratio is 0.2~ 0.4, voids volume : 30~17%, unit weight: 1,710~2,010kg/m3, compressive strength : 45~145kgf/$\textrm{cm}^2$, its pH is more than 11, but is reduced to the proper degree for planting after being neutralized. Kentucky bluegrass covered with planting concrete is grown well. The planting concrete used with blast furnace slag cement shows a better properties at the height, the width and the covering rate by 1.1cm, 0.5mm and 7%, respectively, than those used with ordinary portland cement. Also, the less the paste to aggregate ratio is, the better the plant grows. The orders of the effects of temperature control are as follows; the system of planting concrete with grass>the system of planting concrete without grass>the system of mixed soil>the existed roof system. In case, the planting concrete is placed to the roofs of buildings instead of normal concrete slab, and a number of favorable effect can be expected such as the improvement os environmental factors, the reduction of construction cost, the saving of energy and the reduction of environment load. The future research on the change of a variety of the aggregate conditions and the application of the practical structures should be made, and also the research of the endurance also be performed.

• Journal of the Korea Concrete Institute
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• v.20 no.2
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• pp.175-183
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• 2008

Domestically, application of High Flowing Self-Compacting Concrete (HSCC) is limited to building structures and it is difficult to find examples of application in civil infrastructural constructions. However, in the case of North America and Europe, by introducing precast and prestressed system, HSCC is being used for high-density reinforced bridge members. Hence it is assessed that broadening the utilization of HSCC into areas such as bridges and civil construction is required. Therefore in this research, to apply HSCC to high-density reinforced bridge members, ground granulated blast-furnace slag and fly ash were mixed in binary and ternary systems. Also the dynamical characteristics of HSCC, following 1st class regulations of Japan Society of Civil Engineers (JSCE), were assessed to enable application on high-density reinforced structures. The test results revealed ternary system mixture showed better mechanical characteristics than binary system mixture and the application on high-density reinforced precast bridge members seems possible.

• Journal of the Korea Concrete Institute
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• v.17 no.4 s.88
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• pp.559-567
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• 2005

The objective of this study is to optimize the use of mineral admixtures (silica fume, fly ash, and blast furnace slag) in high-performance concrete for bridge deck overlay. For this purpose, high-performance concrete, incorporating mineral admixtures, was tested for compressive strength and permeability. The Box Behnken design was used to determine the optimum mix proportions of the mineral admixtures. The optimized mix compositions were then technically evaluated. Test results are compare with the performance specification for high performance concrete overlay on bridge deck. The optimum mix proportions were shown to possess acceptable properties. Also, it is possible to save the construction and materials costs result from a reduction In actual material cost and from the use of widely avaliable truck mixers instead of mobile mixers.

• Korean Journal of Metals and Materials
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• v.49 no.1
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• pp.25-31
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• 2011

Solid oxide fuel cells (SOFCs) have many attractive features for widespread applications in generation systems. Recently, stainless steels have attractive materials for metallic bipolar plate because metallic bipolar plates have many benefits compared to others such as graphite and composite bipolar plates. SOFC operates on high temperature of about $800{\sim}1000^{\circ}C$ than other fuel cell systems. Thus, many studies have attempted to reduced the operation temperature of SOFC to about $600{\sim}800^{\circ}C$, which is the intermediate temperature (IT) of SOFC. Low cost and high-temperature corrosion resistance are very important for the practical applications of SOFC in various industries. In this study, two specimens, 304 and 430 stainless steels with and without different pre-surface treatments on the surface were investigated. And, specimens were exposed at high temperature in the box furnace under oxidation atmosphere of $800^{\circ}C$. Oxidation behavior have been investigated with the materials exposed at different times (100 hrs and 400 hrs) by SEM, EDS and XRD. By increasing exposure time, the amount of metal oxide increased in the order like; STS304 < STS430 and As-received < As-polished < Sand-blast specimens.

• Journal of the Korean Recycled Construction Resources Institute
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• v.10 no.4
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• pp.577-583
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• 2022

In this study, the characteristics of self-healing mortars produced using an inorganic self-healing material consisting of ground granulated blast furnace slag, expansion agent, and anhydrite, were investigated. For three types of self-healing mortars with different amounts of the inorganic healing material, compressive strength was measured and the self-healing performance was evaluated through the constant water head permeability test. The healing rate and equivalent crack width according to crack-induced aging were used as indicies of healing performance evaluation. Considering the development of compressive strength of the self-healing mortars, the change in the healing rate with healing periods, and the economic feasibility, the optimal amount of inorganic self-healing materials was suggested as 20 % of the mass of cement.

• Journal of ILASS-Korea
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• v.21 no.4
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• pp.184-194
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• 2016

Many industrial processes require reliable temperature measurements in harsh environments with high temperature, dust, humidity, and pressure. However, commercially-available conventional temperature measurement devices are not suitable for use in such conditions. This study thus proposes a reliable, durable two-color radiation thermometer (RT) for harsh environments that was developed by selecting the appropriate components, designing a suitable mechanical structure, and compensating environmental factors such as absorption by particles and gases. The two-color RT has a simple, compactly-designed probe with a well-structured data acquisition system combined with efficient LabVIEW-based code. As a result, the RT can measure the temperature in real time, ranging from 300 to $900^{\circ}C$ in extremely harsh environments, such as that above the burden zone of a blast furnace. The error in the temperature measurements taken with the proposed two-color RT compared to that obtained using K-type thermocouple readouts was within 6.1 to $1.4^{\circ}C$ at a temperature range from 200 to $700^{\circ}C$. The effects of absorption by gases including $CO_2$, CO and $H_2O$ and the scattering by fine particles were calculated to find the transmittance of the two wavelength bands of operation through the path between the measured burden surface and the two-color probe. This method is applied to determine the transmittance of the short and long wavelength bands to be 0.31 and 0.51, respectively. Accordingly, the signals that were measured were corrected, and the true burden surface temperature was calculated. The proposed two-color RT and the correction method can be applied to measure temperatures in harsh environments where light-absorbing gases and scattering particles exist and optical components can be contaminated.

• Journal of Soil and Groundwater Environment
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• v.21 no.6
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• pp.135-145
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• 2016

MgO recently has been regarded as the alternative material for replacement of cement. The aim of this study is to investigate the effects of accelerated carbonation on the strength development of MgO-based binder which is binary mixtures of magnesium oxide (MgO) with portland cement (PC) or ground granulated blast furnace slag (GGBS) or fly ash (FA). The compressive strengths of all binders were higher in the 20% $CO_2$ condition and for longer curing time. The strength were generally higher as the following order: MgO/PC > MgO/GGBS > MgO/FA system. The binder composed of 20% MgO and 80% PC showed highest compressive strength (38.0MPa) which was higher than PC. The correlation analysis of the porosity and compressive strength showed that compressive strength was higher when porosity was lower. The hydration and carbonation products of MgO including brucite ($Ca(OH)_2$), magnesite ($MgCO_3$) and nesquehonite ($MgCO_3{\cdot}3H_2O$) presumably filled the pores and contributed to strength development. Thermogravimetric analyses elucidated that 0.34 kg of $CO_2$ could be stored the 50% MgO/50% PC binder which performed the maximum $CO_2$ uptake at 20% $CO_2$ condition.

• Journal of the Korea institute for structural maintenance and inspection
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• v.16 no.6
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• pp.56-62
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• 2012

The results presented in this paper form part of an investigation into the optimization of a ternary blended cementitious system based on ordinary Portland cement (OPC)/blast furnace slag(BFS)/fly ash(FA) for the development of ultra high strength concrete. Concrete covering a wide range of BFS/FA blending proportions were investigated. Compressive strength at the ages of 3, 7 and 28 days for concrete specimens containing 0%, 10%, 20% and 30%FA along with 0%, 30%, 40% and 50%BFS as partial cement replacement at a water-binder ratio of 0.18 were investigated. Tests on porosity and pore size distribution were conducted using mercury intrusion porosimetry. The results show that the combination of FA10 and BFS30 can improve both short- and long-term properties of concrete as results of reducing of pores larger than 50nm.

• Proceedings of the Korea Concrete Institute Conference
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• 2008.04a
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• pp.725-728
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• 2008

This study was to establish 3 levels of high fineness fly ash like 4000, 6000, and 8000 class and 30% replacement ratio in order to analyze mechanics and shrinkage properties of concrete by using high fineness fly ash. Furthermore, this study was to make a plan in two levels of water-binder ratio like 40% and 50%. In addition, as a result of measurement by the establishment of combined condition of ternary system as 20% replacement ratio level of three sorts of ground granulated blast furnace slag, there was a tendency to be equal or higher to the plain concrete as the fineness of fly ash increased in strength property. Simultaneously, this study had a tendency in the relationship between the compressive strength and elastic modulus that the more the fineness of fly ash, the more the elastic modulus increased a little. In addition, this study had a tendency that the more elastic modulus moved to the long-term aged one, the more it increased definitely. The effect on the fineness of fly ash remained at a low level in the drying shrinkage. This study has shown that the more the fineness increased, the more the elastic modulus decreased.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.28 no.1A
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• pp.155-163
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• 2008

On the construction site with trends of large scale, high rise and specialization, testing construction of high performance concrete, superior to conventional concrete, is continued to increase. For bridge construction, application of full staging method is gradually decreasing due to noise, dust, and prolonged construction period. Recently, precast construction, which is optimized to urban environment and shorter work period, gains popularity significantly. In bridge structure, overcrowding arrangement of bar is used to ensure its safety. For the manufacturing of overcrowding arrangement of bar, High flowing self-compacting concrete, which is superior to conventional concrete in flowability and compacting property, should be implemented. In this study, the application of blast-furnace slag and fly ash to binary and ternary blended system on the High flowing self-compacting concrete for bridge structure with overcrowding arrangement of bar is evaluated by flowability in accordance with the first class regulations of Japan Society of Civil Engineering (JSCE).