• Journal of the Korea institute for structural maintenance and inspection
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• v.9 no.4
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• pp.177-186
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• 2005

The latest concrete structure has showed that the deterioration of durability has been increased by the damage from salt, carbonization, freezing & thawing and the others. Therefore, the measures for the concrete which has deteriorated durability have been taken. Among them, it has been often used that surface treatment which cuts off the deterioration factors of durability by protecting the surface of concrete. However, troubles such as fracture and rupture in the repair layer have been reported as time goes by due to the difference between the organic repair material like epoxy and concrete properties. Researchers have been developing the repair material which can cut off the deterioration factors of durability such as $CO_2$ gas, chloride ion and water by making the formation of concrete elaborate through the reaction with calcium ion when the surface improving agent is coated on the concrete. The main ingredient of that is inorganic substance which is the same as the concrete property. This study was evaluated the surface improving agent for permeability, watertightness, air-permeability, chemical resistance and elution resistance. As a result, it has been reported that the surface improving agent improves watertightness and air-permeability by penetration more than 10mm within concrete. Therefore, it is concluded that the surface improving agent developed in this research prevents deterioration of concrete durability when it is coated on the concrete structure.

• Journal of the Korean Recycled Construction Resources Institute
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• v.6 no.4
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• pp.119-126
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• 2012

Portland cement production-1.5billion tonnes yearly worldwide-contributes substantially to global atmospheric pollution(7% of total of $CO_2$ emissions). Attempts to increase the utilization of fly ash, by-products from thermal power plant to partially replace the cement in concrete are gathering momentum. But most of fly ash is currently dumped in landfills, thus creating a threat to the environment. Many researches on alkali-activated concrete that does not need the presence of cement as a binder have been carried out recently. Instead, the sources of material such as fly ash, that are rich in Silicon(Si) and Aluminium(Al), are activated by alkaline liquids to produce the binder. Hence concrete with no cement is effect reduction of $CO_2$ gas. In this study, we investigated the influence of the compressive strength of mortar on alkaline activator and curing condition in oder to develop cementless fly ash based alkali-activated concrete. In view of the results, we found out that it was possible for us to make alkali-activated mortar with 70MPa at the age of 28days by using alkaline activator manufactured as 1:1 the mass ratio of 9M NaOH and sodium silicate and applying the atmospheric curing after high temperature at $60^{\circ}C$ for 48hours.

• Journal of the Korea Concrete Institute
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• v.23 no.4
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• pp.487-494
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• 2011

In this research, the possibility of using bottom ash as a binder for the alkali-activated cement mortar is studied. Several experiments were performed to investigate the variation of the material properties according to the mix proportion. In the experimental program, the flowability and compressive strength were evaluated for various values of water/ash ratio, activator/ash ratio, sodium silicate to sodium hydroxide ratio, curing temperature, and the fineness of bottom ash as the main variables. The experimental results showed that high strength of 40 MPa or greater could be achieved in $60^{\circ}C$ high temperature curing condition with proper flowability. For $20^{\circ}C$ ambient temperature curing, the 28 days compressive strength of approximately 30MPa could be obtained although the early-age strength development was very slow. Based on the results, the range of optimized mix design of bottom-ash based alkali-activated cement mortar was suggested. In addition, using the artificial neural network analysis, the flowability and compressive strength were predicted with the difference in the mix proportion of the bottom-ash based alkali-activated cement mortar.

• Journal of Conservation Science
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• v.25 no.4
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• pp.439-450
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• 2009

The purpose of this study is to find out characteristics of the fillers made by epoxy resin (L-30) and filling epoxy resin (L-50) with talc, quartz sand and wollastonite with different mixture ratio of 5%, 50%, 80%, 120%, and 150%. The viscometer and colorimeter were used to measure the viscosity and chromaticity of the fillers. Additionally, IC and SEM were used to reveal characteristics of the filler, and checked ultrasonic wave velocity, compressive strength and contact angle to estimate the stability between the filler and stones which are essential for conservation treatments. The filler mixed with the talc had the lowest value in the ultrasonic wave velocity analysis, and its compressive strength decreased as the mixing rate of talc increased. On the other hand, wollastonite had higher values than others in the ultrasonic wave velocity and the compressive strength regardless of epoxy resin type, also, these values increased as mixing rate increased. The properties of the filler, which include the granularity and shape, have influence on characteristics of the stone conservation adhesives. Thus, the filler type, characteristic, and mixture ratio must be considered for effective conservation treatment.

• Journal of Conservation Science
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• v.35 no.6
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• pp.612-620
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• 2019

A woolen tapestry curtain, owned by the Seoul Museum of Craft Art, is composed of tabby by cotton-warp and wool-weft threads and its patterned part is shown as a tapestry; paint with pigment has been added to it. The chromaticity of this curtain was measured and the substances in the deep red color were confirmed as Hg by an analysis of the ingredients through X-ray fluorescence. This is presumed to be cinnabar or vermilion. Analyses were performed on a total of seven fabric samples, including the warp & weft of the fabric, its trimming, and its back fabric. As a result, the warp of the woolen tapestry curtain was determined to be a cotton fiber with a middle hole or lumen in the cross-section. Furthermore, an infrared peak likewise showed O-H and C-O binding. Wool fibers as wefts were identified with circular and oval cross-sections and IR peaks showed N-H/O-H stretching and amide(-CONH-). The animal hair samples used in the wool fiber are believed to have come from long-tailed goral or goats and the possibility of using easy-to-spin sapsal dog hair is also not to be overlooked. This was determined through a contrast analysis by the Cultural Heritage Administration to identify the animal species used in the tapestry.

• Journal of Conservation Science
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• v.31 no.4
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• pp.411-427
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• 2015

The purpose of the present study is to examine the objects excavated from the archaeological site of the Nogye Village in terms of their relationships with the iron production facilities such as 1ho smithing hearth and 2ho smelting furnace. 32 samples including slags, iron ores, and wall were analyzed to identify the mineralogical and chemical characterization. In addition, in the case of the 1ho smithing hearth slag, differing points of the cross-section were analyzed to examine its formation in depth. The analysis results suggest that the slags from the each site adjacent to the 1ho smithing hearth and 2ho furnace are related to smithing and smelting process respectively. Furthermore, it is possible to draw some conclusions that the aspects of the increased contents of nonferrous elements such as CaO in the slags in comparison with those of the iron ores are due to various factors such as charcoal ash and analytical reasons rather than an addition of CaO as flux.

• Applied Chemistry for Engineering
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• v.18 no.1
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• pp.24-28
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• 2007

The etching of zinc oxide (ZnO) thin films has been studied using a high density plasma in a $Cl_2/Ar$ gas. The etch characteristics of ZnO thin films were systematically investigated on varying $Cl_2$ concentration, coil rf power, dc-bias voltage, and gas pressure. With increasing $Cl_2$ concentration, the etch rate of ZnO thin film increased, the redeposition around the etched patterns decreased but the sidewall slope of the etched patterns slanted. As the coil rf power and dc-bias voltage increased, the etch rates of ZnO thin films increased and etch profiles of ZnO thin films were improved. With increasing gas pressure, the etch rate of ZnO thin films slightly increased but little change in etch profile was observed. Based on these results, the optimal etching conditions of ZnO thin film were selected. Finally, the etching of ZnO thin films with a high degree of anisotropy of approximately $75^{\circ}{\sim}80^{\circ}$ without the redepositions and residues was successfully achieved at the etching conditions of 20% $Cl_2$ concentration, coil rf power of 1000 W, dc-bias voltage of 400 V, and gas pressure of 5 mTorr.

• Journal of the Korean Recycled Construction Resources Institute
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• v.6 no.1
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• pp.63-71
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• 2011

Portland cement production is under critical review due to high amount of $CO_2$ gas released to the atmosphere. Attempts to increase the utilization of a by-products such as fly ash and ground granulated blast-furnace slag to partially replace the cement in concrete are gathering momentum. But most of by-products is currently dumped in landfills, thus creating a threat to the environment. Many researches on alkali-activated concrete that does not need the presence of cement as a binder have been carried out recently. In this study, we investigated the influence of alkali activator and superplasticizer on the flowability and compressive strength of the alkali-activated mortar in oder to develop cementless alkali-activated concrete using blast furnace slag. In view of the results, we found out that the type and mixture ratio of alkali activator, the type and adding order of superplasticizer results to be significant factors. When cementless alkali-activated mortar using blast furnace slag manufactured with 1:1 the mass ratio of 9M NaOH and sodium silicate, and added superplasticizer before alkali activator in the mixer, we can be secured workability with 180 mm of flow during 1 hours and compressive strength of about 50 MPa under $20^{\circ}C$ curing condition at age of 28days.

• Journal of Conservation Science
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• v.28 no.4
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• pp.377-385
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• 2012

Anoxic treatments using argon and nitrogen gas in controlled atmospheres have been used as a alternative to methyl bromide for insect disinfection in museums. Anoxic chamber system was manufactured and installed at The National Folk Museum of Korea for the first time in Korea. The internal capacity of anoxic chamber is 0.5m3 in which is able to use argon, nitrogen and carbon dioxide gas. This system is equipped with oxygen concentration, temperature and ralative humidity control devices and automatically controlled oxygen concentration from 0.01 to 20%, temperature from 10 to $50^{\circ}C$ and relative humidity 30 to 80%. To control the oxygen concentration, anoxic chamber system is adopted semi-dynamic method which supplies mixture of humidified gas and dry gas whenever oxygen concentration in chamber becomes higher than setting value. It has kept regularly oxygen concentration, temperature and relative humidity for 20 days using argon gas. To evaluate the disinfection of cigarette beetle larvae and adults and varied carpet beetle larvae, the anoxic chamber system maintained 0.01% of oxygen concentration, $25^{\circ}C$ in temperature and 50% in relative humidity for 30 days. Cigarette beetle larvae were killed in 7 days and adults in 3~5 days. And varied carpet beetle larvae were killed in 3 days. It reaches the conclusion form the evaluation this anoxic chamber system can be used to develop anoxic treatment as an alternative of methyl bromide for insect disinfection of infested cultural properties in museums.

• Resources Recycling
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• v.18 no.2
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• pp.39-50
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• 2009

Portland cement production is under critical review due to high amount of $CO_2$ gas released to the atmosphere. Attempts to increase the utilization of fly ash, a by-products from thermal power plant to partially replace the cement in concrete are gathering momentum. But most of fly ash is currently dumped in landfills, thus creating a threat to the environment. Many researches on alkali-activated concrete that does not need the presence of cement as a binder have been carried out recently. Instead, the source of material such as fly ash, that are rich in Silicon(Si) and Aluminium(Al), are activated by alkaline liquids to produce the binder. Hence concrete with no cement is effective in the reduction of $CO_2$ gas. In this study, we investigated the influence of the compressive strength of mortar on alkaline activator and curing condition in order to develop cementless fly ash based alkali-activated concrete. In view of the results, we found out that it was possible for us to make alkali-activated mortar with 70MPa at the age of 28days by using alkaline activator manufactured as 1:1 the mass ratio of 9M NaOH and sodium silicate and applying the atmospheric curing after high temperature at $60^{\circ}C$ for 48hours.