• Journal of Conservation Science
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• v.35 no.6
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• pp.573-587
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• 2019

In this study, reproducing specimens were made from mixing domestically produced magnetite, clay and non-plastic raw materials to reproduce the pigments used in the manufacture of traditional cheolhwa buncheong stoneware. In order to reveal the color fomation of glaze, 30 specimens with good color development were analyzed scientifically. Magnetite, which is the main raw material of the pigment, is a pigment capable of creating a dark black color in a reducing environment at 1,200℃. However, it reacts with the additionally added lime component and discolors to greenish yellow color in oxidizing environment at 1,230℃. Hematite is not significantly affected by the firing temperature and environment, but develops a dark black color when mixed with clay with iron content of more than 10%. The fluidity of the pigment is determined by R₂O₃/RO₂ value, which also affects the color development. In the microtexture observation, the color formation of the glaze layer and the iron oxide crystals identified some differences depending on the particle size of the pigment and the firing environment. Reproduced specimens made of magnetite are present in the form of aggregates of iron oxide in the interface between glaze layer and slip layer in the oxidizing environment at 1,200℃. However, in the reducing environment, aggregates of iron oxides do not exist in the reproduced specimens, and they are homogeneously distributed in the glaze layer and formed a dark black color. In contrast, hematite-based specimens form dendritic structures in the glaze layer in an oxidizing environment and develop black.

• 기계와재료
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• v.11 no.3 s.41
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• pp.147-157
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• 1999

• Journal of the Korean Society for Environmental Technology
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• v.19 no.6
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• pp.493-502
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• 2018

The purpose of this study was to develop EM media for water treatment and to remove nitrogen and phosphorus which cause water algae boom in water system. The ideal mixing ratio of raw material such as clay: zeolite: vermiculite: activated carbon for manufacturing the EM media was 10: 2.5: 0.1: 2, and the calcination temperature was $700^{\circ}C$. The comparison of the physical properties of manufactures using distilled water and EM activated liquid as the material mixture are as follows. Porosity and density of EM media were 39.98 % and $1.13kg/m^3$, adsorption efficiencies of nitrogen and phosphorus were 69.3 % and 38.9 %. In contrast, porosity and density of distilled water media were 37.80 % and $1.11kg/m^3$, and adsorption efficiencies of nitrogen and phosphorus were 62.5 % and 37.8 %. The adsorption rate of nitrogen and phosphorus in the EM media was higher than that of the distilled water made one by 6.8 % and 1.1 %, respectively. The adsorption characteristics of the media to nitrogen and phosphorus could be expressed by the Freudlich adsorption isotherm. The change of calcination time did not affect the adsorption efficiency of phosphorus and nitrogen when EM media was formed, but it was considered that it affects the strength of media. Nitrogen removal efficiency was the best record in 4 hours of calcination time and 3 hours of calcination time in phosphorus removal efficiency.

• Journal of the Korean Geotechnical Society
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• v.17 no.4
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• pp.191-198
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• 2001

국내 도로포장의 주요 파손형태는 주변환경 및 반복 교통하중 조건에 의한 소성변형(rutting), 피로균열, 반사균열, 온도균열 등이 있는데, 포장이 설계수명에 도달하기 이전에 주로 발생하며 이로 인한 도로포장의 유지관리에 막대한 국가예산이 낭비되고 있는 실정이다. 본 연구에서는 토목섬유 아스팔트 포장 시스템을 체계적으로 정립하기 위해 휠트래킹 시험과 균열저항성 시험을 수행하여 토목섬유 아스팔트 포장의 소성변형 및 균열 저항성을 분석하였다. 이러한 실험결과를 통해 아스팔트 포장에서의 토목섬유 보강 효과가 평가되었다.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2006.04a
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• pp.379-382
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• 2006

본 연구에서는 다양한 토지이용의 불교란 토양칼럼 시료를 대상으로 토양 물리화학 특성 및 자연강우에 대한 토양배수 양상을 분석하였다. 공극률은 토양컬럼에서의 유효공극률과 투수계수 및 자연강우에 대한 배수율과 대체로 정의 상관관계를 보인다. 미국 통일분류법에 따라 토양을 분류하였을 때 소성성이 낮은 실트질 토양과 점토질 토양은 유효공극률이 낮으면서 배수율도 낮고, 소성성이 없는 실트질이 섞인 자갈(유구-논)과 실트질 모래는 유효공극률이 비교적 높으면서 배수율이 다소 높았다. 불교란 토양컬럼을 완전 포화상태에서 자연배수할 때 대부분의 토양은 50시간 전후로 거의 다. 배수되며 $150{\sim}200$시간 경과되면 거의 모든 토양에서 완전배수가 되었다. 일부 500여시간이 경과되어도 지속적으로 배수되는 토양이 있는데 이는 토양수분보유특성에 기인하는 것으로 사료된다. 배수량으로 가정한 함양량 실측실험에서는 오송(전의)임야 > 무주-밭, 무주-논 > 유구-임야 > 김해-밭 > 유구-논, 유구-밭 순으로 높았으며 이들 시료들의 함양률은 50% 이상이었다. 토성에 따른 자연강우 배수상태를 보면, 소성성이 낮은 실트질 토양의 배수율이 낮고, 실트질 모래는 다양한 배수상태를 보이나 대체로 배수율이 높다. 그리고 1차, 2차 실험에서 선행 강우 5mm 미만은 토양배수에 영향을 미치지 않았다.

• Journal of Korean Society of Environmental Engineers
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• v.31 no.5
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• pp.371-377
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• 2009

In oxy-fuel combustion, $CO_2$ concentration in the flue gas may be enriched up to 95% owing to the gas recirculation. Under the high $CO_2$ concentration, the calcination characteristic of limestone is different from that of the conventional air combustion system. In this study, three types of limestone taken from different regions in Korea were used as $SO_2$ absorbent and their calcination characteristics depending on calcination temperature were investigated. The experiments were performed to examine the effects of operating variables such as absorbent species, reaction temperatures on the $SO_2$ removal efficiency and reacted limestone particles were captured to examine the sulfur contents. The degree of calcination and the specific surface area increased with calcination temperature and $SO_2$ removal efficiency increased with reaction temperature. The results showed remarkable difference in $SO_2$ removal efficiencies between the limestone types. The sulfur content of the reacted limestone with the highest $SO_2$ removal efficiency was about 10%.

• Journal of the Korea Concrete Institute
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• v.19 no.2
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• pp.233-239
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• 2007

The main objective of this study was to evaluate the effect of recycled PET fiber made from waste PET bottle on the control of plastic shrinkage cracking of cement based composites. PET is blown as a plastic material and used in a variety products such as a beverage bottle. However, waste PET bottles are thrown after the usage, raising huge problems in terms of the environment. Thus, the research on the method to recycle the PET bottles indicates important aspects in environment and economy. The method to recycle waste PET bottles as a reinforcing fiber for cement based composites is one of effective methods in terms of the recycle of waste PET bottles. In this research, the effect of recycled PET fiber geometry and length on the control of plastic shrinkage was examined through thin slab tests. A test program was carried out to understand the influence of fiber geometry, length and fiber volume fraction. Three type of recycled PET fibers including straight, twist crimped and embossed type. Three volume fraction and two fiber length were investigated for each of the three fiber geometry. Test results indicated that recycled PET fibers are effective in controlling plastic shrinkage cracking in cement based composites. In respect to effect of length of fiber, longer fiber was observed to have efficient cracking controlling with low volume fraction in same fiber geometry while shorter fiber controled plastic shrinkage cracking efficiently as addition rate increase. Also, embossed type fibers were more effective in controlling plastic shrinkage cracking than other geometry fiber at low volume fraction. But, for high volume fraction, straight type fibers were most effective in plastic shrinkage cracking controlling in cement based composites.

• Economic and Environmental Geology
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• v.47 no.6
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• pp.645-655
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• 2014

In order to obtain pure metallic Te from gold concentrate, roasting treatment, hypochlorite leaching, Fe removal and electrolysis experiments were carried out. The contents of Au, Ag and Te from the concentrate sample and roasted sample were much more soluble in the hypochlorite solution than in aqua regia digestion, whereas the metals Pb, Zn, Fe and Cu were easier to leach with the aqua regia than the hypochlorite. With the addition of NaOH in the hypochlorite leaching solution prior to electrolysis, the Fe removal rate achieved was only 96% in the concentrate sample, while it reached 98% in the roasted sample. The results of electrolysis for 240 min, 98% of the metallic copper was recovered from the concentrate sample, while 99% was obtained from the roasted sample due to the removal of S by roasting. The amount of anode slime was also greater in the electrolytic solution with the roasted sample than with the concentrate sample. The results on the anode slime after the magnetic separation process showed the amount of metallic pure native tellurium recovered was greater in the roasted sample than in the concentrate sample.

• Proceedings of the Korean Vacuum Society Conference
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• 2012.08a
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• pp.202-202
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• 2012

염료감응태양전지(DSSC)의 광변환 효율을 향상시키기 위하여 진공챔버에서 450도 고온에서 O2, Ar, and N2 혼합가스를 주입하여 다양한 plasma로 TiO2 박막을 처리하면서 소성시켰다. TiO2 표면을 cleaning하고 활성화함으로서 염료의 결합력을 향상시키는 것 외에 TiO2 내부의 oxygen vacancy를 변화를 관찰하였다. 실험에 사용한 박막은 glass 위에 FTO 박막을 입히고, 다공성 TiO2 나노입자 박막을 코팅하여 제조하였다(porous TiO2 나노입자(${\sim}12{\mu}m$)/FTO(Fluorine doped Tin oxide; $1{\mu}m$)/glass). 완성된 광전극에 대해서 XRD, XPS, EIS, FE-SEM 등을 이용하여 분석하였다. 또한 이렇게 전처리된 광전극을 사용한 DSSC를 제작하였다. 그리고 Solar-simulator를 통해 그 효율을 측정하여 '플라즈마환경에서 소성된 광전극에 대한 DSSC의 광변환효율에 미치는 효과'을 고찰하였다.

• Korean Journal of Mineralogy and Petrology
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• v.33 no.4
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• pp.407-417
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• 2020

The capacity of the designated landfill site for asbestos-containing waste is approaching its limit because the amount of asbestos-containing slate is increasing every year. There is a need for a method that can safely and inexpensively treat asbestos-containing slate in large capacity and at the same time recycle it. A cement kiln can be an alternative for heat treatment of asbestos-containing slate. We intend to develop a pilot scale device that can simulate the high temperature environment of a cement kiln using a high temperature plasma reactor in this study. In addition, this reactor can be used to inactivate asbestos in the slate and to synthesize one of the minerals of cement, to confirm the possibility of recycling as a cement raw material. The high-temperature plasma reactor as a pilot scale experimental apparatus was manufactured by downsizing to 1/50 the size of an actual cement kiln. The experimental conditions for the deactivation test of the asbestos-containing slate are the same as the firing time of the cement kiln, increasing the temperature to 200-2,000℃ at 100℃ intervals for 20 minutes. XRD, PLM, and TEM-EDS analyses were used to characterize mineralogical characteristics of the slate before and after treatment. It was confirmed that chrysotile [Mg3Si2O5(OH)4] and calcite (CaCO3) in the slate was transformed into forsterite (Mg2SiO4) and calcium silicate (Ca2SiO4), a cement constituent mineral, at 1,500℃ or higher. Therefore, this study may be suggested the economically and safely inactivating large capacity asbestos-containing slate using a cement kiln and the inactivated slate via heat treatment can be recycled as a cement raw material.