• Geomechanics and Engineering
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• v.25 no.1
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• pp.31-40
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• 2021

Injection grouting is one of the most common ground improvement practice to increase the strength and reduce the hydraulic conductivity of soils. Owing to the environmental concerns of conventional grout materials, such as cement-based or silicate-based materials, bio-inspired biogeotechnical approaches are considered to be new sustainable and environmentally friendly ground improvement methods. Biopolymers, which are excretory products from living organisms, have been shown to significantly reduce the hydraulic conductivity via pore-clogging and increase the strength of soils. To study the practical application of biopolymers for seepage and ground water control, in this study, we explored the injection capabilities of biopolymer-based grout materials in both linear aperture and particulate media (i.e., sand and glassbeads) considering different injection pressures, biopolymer concentrations, and flow channel geometries. The hydraulic conductivity control of a biopolymer-based grout material was evaluated after injection into sandy soil under confined boundary conditions. The results showed that the performance of xanthan gum injection was mainly affected by the injection pressure and pore geometry (e.g., porosity) inside the soil. Additionally, with an increase in the xanthan gum concentration, the injection efficiency diminished while the hydraulic conductivity reduction efficiency enhanced significantly. The results of this study provide the potential capabilities of injection grouting to be performed with biopolymer-based materials for field application.

• Journal of the Architectural Institute of Korea Structure & Construction
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• v.34 no.3
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• pp.37-42
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• 2018

The use of fly ash in construction materials is increasing worldwide due the various advantages of using it, such as to produce durable concrete, or to use less cement and thus lower carbon dioxide emissions. The quality of fly ash is often determined by loss on ignition value (LOI), where an upper limit of LOI is set in each country for quality control purpose. However, due to many reasons, production of high LOI fly ash is increasing that cannot be utilized in concrete, ending up in landfill. In this study, the effect of fly ash use in cementitious materials on nitrogen oxides adsorption is examined. In particular, the effect of using high LOI, and thus high carbon content fly ash on nitrogen oxides adsorption is investigated. The results suggest that the higher carbon content fly ash is related to higher nitrogen dioxide adsorption, although normal fly ash was also more effective in nitrogen dioxide adsorption than ordinary portland cement. Also, higher replacement rate of up to 40% of fly ash is beneficial for nitrogen dioxide adsorption. These results demonstrate that high carbon fly ash can be used as construction materials in an environmentally friendly way where strength requirement is low and where nitrogen oxides emissions are high.

• Journal of the Korean Society of Environmental Restoration Technology
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• v.6 no.4
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• pp.74-84
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• 2003

This study focuses on the technology to reduce destruction and damages of an ecosystem in the process of road construction. The authors investigated the ecological conservation activities and restoration technology which were applied to the construction of 2 bridges in Japan. The key results are as following : First, the most important thing in constructing eco-road was the linear design. Second, we need to adopt the environmental construction forms and materials to the design of structure. Finally, we have to use environment-friendly methods for the sake of the ecosystem at the real construction stage. Adopting those technologies has at least a few merits. First, we can achieve out goals : conservation and restoration in the local habitat. Second, we can save money instead of building a eco-bridge. There is a further advantage which makes it possible to develop environment-friendly technologies than before by drawing developers' attention.

• Proceedings of the Korean Geotechical Society Conference
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• 2008.03a
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• pp.762-765
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• 2008

Shotcrete is NATM technique after tunnel excavation as major tunnel support for ground stability, curtail of execution period and reduction of execution expenses instead of general lining method. It is trend using constantly shotcrete lining. This high-strength shotcrete is require to use as constantly shotcrete lining. This brought out the solution of environmental pollution and harmfulness about human. Accordingly, in this study Specimens of strength measurement was made to develop shotcrete possible to develop in early materials with Cement Mineral Accelerator as NATM method construction. It's compared with existing shotcrete material, Unconfined Compression test, flexural strength test were experimented. The fish poison test was experimented to evaluate an influence of environment. On results of test, Unconfined Compressive Strength and flexural strength was equivalent with 28-day strength of existing material. On results of fish poison evaluation research subject material was founded environmentally friendly for existing shotcrete.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.67 no.9
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• pp.1181-1188
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• 2018

In order to develop new insulating materials for GIS Spacer using environmentally friendly insulating gas, three kinds of dispersed liquid nano composites of solid epoxy /nano layered silicate filled material were prepared. And the epoxy/nano/micro silica composite was prepared by mixing epoxy/nano 3 phr dispersion/4 kinds of filler contents(40,50,60, 70wt%). The electrical insulation breakdown strengths of the nano and nano/micro mixed composites were evaluated by using 8 kinds of samples including the original epoxy. The mechanical tensile strength of the epoxy / nano / micro silica composite were evaluated, also. The TEM was measured to evaluate the internal structure of nano/micro composites. As a result, it was confirmed that the layered silicate nano particles was exfoliated through the process of inserting epoxy resin between silicate layers and the layers. In addition, dispersion of nano / micro silica resulted in improvement of electrical insulation breakdown strength with increase of filling amount of dense tissue with nanoparticles inserted between microparticles. In addition, the tensile strength showed a similar tendency, and as the content of microsilica filler increased, the mechanical improvement was further increased.

• Structural Engineering and Mechanics
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• v.86 no.2
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• pp.181-195
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• 2023

To predict the rheological behaviours along with the compressive strength of self-compacting concrete that incorporates environmentally friendly ingredients as cement substitutes, a comparative evaluation of machine learning methods is conducted. To model four parameters, slump flow diameter, L-box ratio, V-funnel time, as well as compressive strength at 28 days-a complete mix design dataset from available pieces of literature is gathered and used to construct the suggested machine learning standards, SVM, MARS, and Mp5-MT. Six input variables-the amount of binder, the percentage of SCMs, the proportion of water to the binder, the amount of fine and coarse aggregates, and the amount of superplasticizer are grouped in a particular pattern. For optimizing the hyper-parameters of the MARS model with the lowest possible prediction error, a gravitational search algorithm (GSA) is required. In terms of the correlation coefficient for modelling slump flow diameter, L-box ratio, V-funnel duration, and compressive strength, the prediction results showed that MARS combined with GSA could improve the accuracy of the solo MARS model with 1.35%, 11.1%, 2.3%, as well as 1.07%. By contrast, Mp5-MT often demonstrates greater identification capability and more accurate prediction in comparison to MARS-GSA, and it may be regarded as an efficient approach to forecasting the rheological behaviors and compressive strength of SCC in infrastructure practice.

• Steel and Composite Structures
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• v.50 no.4
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• pp.443-458
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• 2024

The construction industry, one of the biggest producers of greenhouse emissions, is under a lot of pressure as a result of growing worries about how climate change may affect local communities. Geopolymer concrete (GPC) has emerged as a feasible choice for construction materials as a result of the environmental issues connected to the manufacture of cement. The findings of this study contribute to the development of machine learning methods for estimating the properties of eco-friendly concrete, which might be used in lieu of traditional concrete to reduce CO₂ emissions in the building industry. In the present work, the compressive strength (f_c) of GPC is calculated using random forests regression (RFR) methodology where natural zeolite (NZ) and silica fume (SF) replace ground granulated blast-furnace slag (GGBFS). From the literature, a thorough set of experimental experiments on GPC samples were compiled, totaling 254 data rows. The considered RFR integrated with artificial hummingbird optimization (AHA), black widow optimization algorithm (BWOA), and chimp optimization algorithm (ChOA), abbreviated as ARFR, BRFR, and CRFR. The outcomes obtained for RFR models demonstrated satisfactory performance across all evaluation metrics in the prediction procedure. For R² metric, the CRFR model gained 0.9988 and 0.9981 in the train and test data set higher than those for BRFR (0.9982 and 0.9969), followed by ARFR (0.9971 and 0.9956). Some other error and distribution metrics depicted a roughly 50% improvement for CRFR respect to ARFR.

• Korean Journal of Organic Agriculture
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• v.22 no.1
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• pp.129-145
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• 2014

To evaluate the potential of Hypochoeris radicata L. for the development of environment-friendly organic materials, its growth characteristics, allelopathic effects and antifungal activity was investigated. The growth characteristics of H. radicata L. was investigated by measuring comparative number of shoot and flower, and the diameters of clones in mowing areas and non-mowing areas, respectively. As a result, the number of shoot and flower, and diameters of clones of H. radicata L. grown in mowing areas were much higher than those grown in non-mowing areas. Water extracts of H. radicata L. inhibited seed germination, and shoot, root and root hair growth of 14 test plants including Trifolium pratense, Festuca myuros, Bidens bipinnata and finally reduced heir biomass remarkably. The inhibitory effect of the extract was different depending on the kind and the part of tested plants. The extracts showed high antifungal activity against Pythium spp. and Phytophthora However, it showed comparably less antifungal activity against Rhizoctonia solani than Pythium spp. and Phytophthora. In conclusion, cutting H. radicata L. resulted increase of its vegetative and seed propagation and helped it to form large colony. Also it had an effect on growth of microbes and germination and growth of other plants. Therefore H. radicata L. holds the competitive dominant position in plant ecosystem in Jeju Island and it can be used as candidate of environment-friendly organic materials.

• Journal of the Korean Wood Science and Technology
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• v.37 no.6
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• pp.537-545
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• 2009

The objective of this study was to investigate potential usage of environmentally friendly building materials, liquid mortar and dry cement mortar mixed with charcoal, based on the test of their physical and chemical properties. From the test results of physical and chemical properties of the liquid mortar mixed with charcoal, liquid mortar containing over 20% of charcoal, the consistency viscosity and the non-volatile content met a standard requirement. Drying time was delayed with increase in charcoal contents in the liquid mortar, however they were fully cured within 60 minutes in all treated levels. Other properties were acceptable at standard requirement. From the results, it was found that the proper charcoal addition level to the liquid mortar was 25%. In the results on dry cement, it was found that samples containing 5% of charcoal showed the maximum compressive strength, whereas samples containing over 20% of charcoal did not reach the minimum requirement of KS standard. Water retention ability constantly increased as the charcoal ratio increased. The conventional dry cement mortar adsorbed 59.5% of it, in the test of adsorption rate on ammonia gas, whereas cement mortar containing 10% of charcoal showed 71.6% of ammonia gas adsorption.

• Journal of the Korean Institute of Gas
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• v.27 no.3
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• pp.1-10
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• 2023

Due to the development of the industrial revolution, regulations on exhaust emissions have been continuously strengthened to reduce the rapidly increasing greenhouse gas emissions. The use of environmentally friendly fuels is essential to meet these regulations. Hydrogen has been attracting attention as a future environmentally friendly fuel, but due to its material properties, it faces significant challenges in handling and storage. As an alternative, ammonia has been proposed. Ammonia can be easily liquefied at room temperature compared to hydrogen and has a high energy density. In order to examine the applicability of ammonia as an engine fuel, experiments were conducted to investigate the effects of changes in combustion control parameters in a direct injection ammonia combustion engine. The experiments were conducted by varying two variables: spark timing and excessive air ratio. Observations were made on combustion stability and the trends of exhaust emissions such as nitrogen oxides and unburned ammonia under the conditions of an engine speed of 1,500 rpm and medium to high loads (brake torque of 200 Nm). By optimizing the combustion control parameters, conditions for stable combustion even when using ammonia as the sole fuel were identified, and plans are underway to apply strategies for future expansion of the operating range.