• Proceedings of the Korean Society of Dyers and Finishers Conference
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• 2009.03a
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• pp.241-242
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• 2009

• Journal of the Korean Wood Science and Technology
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• v.31 no.4
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• pp.44-49
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• 2003

This study was carried out to evaluate the weathering durability of waterborne preservative (AAC, ACQ, CCA, CuAz) treated Japanese red pine (Pinus densiflora S. et Z.) sapwood samples by accelerated weathering, and to find out the factor of stability. When considered the color changes, weight losses, surface degradation, and microstructure changes due to weathering, ACQ-, CCA-, and CuAz-treated samples were durable against weathering; the weathering durability of AAC-treated samples was poor and similar to untreated controls. The lignin content in aqueous extracts collected from ACQ-, CCA-, and CuAz-treated samples during weathering was lower than that from untreated and AAC-treated ones. From these findings, we might concluded that weathering durability of ACQ-, CCA-, and CuAz-treated samples was enhanced by the fixation of preservative component(s) onto the lignin structure, which is very susceptible to weathering.

• Computers and Concrete
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• v.12 no.6
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• pp.755-774
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• 2013

Considering the well known environmental issues of cement manufacturing (direct and indirect levels of $CO_2$ emissions), clinker replacement by supplementary cementing materials (SCM) can be a very promising first step in reducing considerably the associated emissions. However, such a reduction is possible up to a particular level of SCM utilization, influenced by the rate of its pozzolanic reaction. In this study a (4-step) structured methodology is proposed in order to be able to further adjust the concrete mix design of a particular SCM, in achieving additional reduction of the associated levels of $CO_2$ emissions and being at the same time accepted from a derived concrete strength and service life point of view. On this note, the aim of this study is twofold. To evaluate the environmental contribution of each concrete component and to provide the best possible mix design configuration, balanced between the principles of sustainability (low environmental cost) and durability (accepted concrete strength and service life ). It is shown that such a balance can be achieved, by utilising SCM by-products in the concrete mix, reducing in this way the fixed environmental emissions without compromising the long-term safety and durability of the structure.

• Proceedings of the Korean Geotechical Society Conference
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• 2009.03a
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• pp.836-843
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• 2009

The Water Glass grouting method has been applied frequently to impermeable grouting in practice. But there is raising problems which are durability decrease by passage time and environmentally adverse effect. So, Earth Natural Grouting method which uses micro cement is developed to overcomes the problems of the Water Glass grouting method. And it is displayed ground injection extent like Water Glass grouting method. For verifying impermeability of ENG, it is carried out a triaxial permeability test about manufacturing specimen of ENG, SGR method which is a presentative Water Glass grouting method. Although Coefficient of permeability, k, of SGR is measured a little high than k of ENG whose value is $a{\times}10^{-6}cm/sec$, the value of ENG belong to impermeable rage. And, k of SGR shows relatively rapid increase according to cure time due to durability decrease of water glass. Also, in-situ test result of ENG has similar value with SGR method for similar ground.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2005.11a
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• pp.29-32
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• 2005

Recently, for the problem solution of demand and supply imbalance of fine aggregate due to the shortage of natural fine aggregate and the environment regulation on sea sand extraction in the construction field, the studies for the application of recycled fine aggregate using waste concrete are being progressed versatilely. The purpose of this study is to investigate quality of recycled fine aggregate manufactured by drying manufacturing system which is the manufacture method of high duality recycled fine aggregate, and to analyze on thehardened and durability properties of recycled concrete using it. Therefore it is to present the fundamental data for application and utilization of recycled concrete. The results of this study are as follows; Quality of recycled fine aggregate by drying manufacturing system is improved, and compressive strength, carbonation depth and chloride ion penetration depth of recycled concrete using high quality recycled fine aggregate are similar to those of normal concrete using natural and crashed sand. But, resistance to $H_{2}SO_{4}$ show decreased somewhat.

• Advances in concrete construction
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• v.11 no.2
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• pp.151-161
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• 2021

The major shortcoming of concrete in most of the applications is its high self-weight and thermal conductivity. The emerging trend to overcome these shortcomings is the use of foam-concrete, which is a lightweight concrete consisting of cement, filler, water and a foaming agent. This study aims at the development of a cost-effective high-volume fly-ash foam-concrete insulation wall cladding for existing buildings using natural fiber like rice straw in different proportions. The paper reports the results of systematic studies on various mechanical, acoustic, thermal and durability properties of foam-concrete with and without replacement of cement by fly-ash. Fly-ash replaces 60 percent by weight of cement in foam-concrete. The water-solid ratio of 0.3, the filler ratio of 1:1 by weight, and the density of 1100 kg/㎥ (approx.) are fixed for all the mixes. Rice straw at 1%, 3% and 5% by weight of cement was added to improve the thermal and acoustic efficiency. From the investigations, it was inferred that the strength properties were increased with fly-ash replacement up to 1% rice straw addition. In furtherance, addition of rice straw and fly-ash resulted in improved acoustic and thermal properties.

• The Journal of Natural Sciences
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• v.8 no.2
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• pp.111-118
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• 1996

In order to improve the chemical durability of glass in the $Na_2O$-CaO-$SiO_2$ system, it was investigated in the effect of $B_2O_3$ and ZnO addition and changing amount of each composition, $Na_2O$, $Al_2O_3$, $Li_2O$. In this minimize the change of softening point of glass was as follow.(wt%)$B_2O_3$:3.36%, ZnO:2.88%, $Na_2O$:9.93%, $Al_2O_3$, $Li_2O$:0.19%, $SiO_2$:70.56%, CaO:11.22%, $K_2O$:0.14%

• Geomechanics and Engineering
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• v.33 no.1
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• pp.29-40
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• 2023

Xanthan gum and starch compound biopolymer (XS), an environmentally friendly soil-binding material produced from natural resources, has been suggested as a slope protection material to enhance soil strength and erosion resistance. Insufficient wet strength and the consequent durability concerns remain, despite XS biopolymer-soil treatment showing high strength and erosion resistance in the dried state, even with a small dosage of soil mass. These concerns need to be solved to improve the field applicability and post-stability of this treatment. This study explored the utilization of an alkaline-based cation crosslinking method using calcium hydroxide and sodium hydroxide to induce non-thermal gelation, resulting in the enhancement of the wet strength and durability of biopolymer-treated soil. Laboratory experiments were conducted to assess the unconfined compressive strength and cyclic wetting-drying durability performance of the treated soil using a selected recipe based on a preliminary gel formation test. The results demonstrated that the uniformity of the gel structure and gelling time varied depending on the ratio of crosslinkers to biopolymer; consequently, the strength of the soil was affected. Subsequently, site soil treated with the recipe, which showed the best performance in indoor assessment, was implemented on the field slope at the bridge abutment via compaction and pressurized spraying methods to assess feasibility in field implementation. Moreover, the variation in surface soil hardness was monitored periodically for one year. Both slopes implemented by the two construction methods showed sufficient stability against detachment and scouring, with a higher soil hardness index than the natural slope for a year.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.22 no.2
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• pp.205-212
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• 1998

Experiments were conducted to investigate the temperature profile and the emissions conversion efficiency of catalytic converters for natural gas vehicles. Two types of the catalyst structure and several transient engine operating conditions were used. The dual-bed catalyst effectively reduced the emissions in a transient period due to the low heat capacity of the front bed. The lanthanoid additives were effective in improving catalyst durability. When the natural gas fueled engine were operated outside of a very narrow window of excess air ratio (from 0.993 to 1.004), the HC and NOx conversion efficiency dropped off. The drop-off were especially fast on the lean side of the window.

• Transactions of the Korean Society of Automotive Engineers
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• v.22 no.6
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• pp.128-133
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• 2014

In this study, Two kinds of pad models with different configurations as the part of brake system are investigated by structural and fatigue analyses. As the maximum equivalent stress of model 2 becomes higher to the extent of 60% than that of model 1, model 2 can endure more load than model 1. In cases of two kinds of models, the maximum fatigue life at 'Sample history' becomes longer 60 times than 'SAE bracket history' and this life in case of 'SAE transmission' becomes longer 3.5 times than the case of 'SAE bracket history'. Maximum fatigue damages in cases of 'SAE bracket history', 'SAE transmission' and 'Sample history' at model 1 become higher than model 2. Model 2 is thought to have more fatigue durability than model 1. These study results can be effectively utilized with the design of brake pad by anticipating and investigating prevention and durability against its fatigue damage.