• Tunnel and Underground Space
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• 제28권1호
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• pp.97-110
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• 2018

The application of sprayed waterproofing membrane with high adhesion and ductility is considered to be promising as a measure for repair and reinforcement of a tunnel structure. Therefore, a powder-type and one-component membrane prototype with high tensile and bond strengths was made in this study. Then, its reinforcement effect on a shield segment was evaluated by carrying out a series of full-scale loading tests of segment specimens on which the membrane was sprayed. From the tests, it was confirmed that the initial cracking loads increased by approximately 34% due to cracking retardation by membrane coating. Even though the increase of failure loads were not so high as cracking loads, the strain-softening behaviors were observed from specimens coated by the membrane. Therefore, it is expected that the membrane coated on the inner surface of a lining might be effective in preventing its brittle failure.

• Journal of the Mineralogical Society of Korea
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• 제19권3호
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• pp.129-138
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• 2006

In this study, we identified the secondary precipitates from Samsan-jeil and Sambong mine, Goseong, Gyeongnam by means of scanning electron microscopy, electron probe microanalysis and X-ray powder diffraction analysis. Copper sulfide minerals had been produced from the mines during last few decades, however they are not worked. White and blue precipitates were found at the downstream of mine rock dump at Sambong mine and green one was at Samsan-jeil mine. The white precipitate covered the host rock surface with thickness of $30{\mu}m$, and is a kind of diatom with $10{\mu}m$ in length and $3{\mu}m$ in width. It is a species Fragilaria constuens, which is contained a order Pennales(pennate diatom) and lives in fresh water. The blue precipitate is the alteration product of chalcopyrite. It resultes in the increase in the ratio Cu:Fe from 5 to 13. The green precipitate has worm-like morphology with $10{\sim}20nm$ in diameter and $200{\sim}300nm$ in length. It is mainly composed of secondary copper sulfate such as woodwardite. However, it could be formed by the activity of microorganism, because the copper content is more than any secondary copper sulfate reported in copper sulfide mine. In order to identity the green precipitate exactly, the further research is needed.

• The Journal of the Petrological Society of Korea
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• 제25권2호
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• pp.107-119
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• 2016

Trace element abundances in the igneous rocks are important data for petrogenetic interpretation. Their concentrations are generally measured using ICP-MS from the dissolved solution. The acid digestion of rock powder can be performed by conventional teflon vial or pressure bomb. In this paper, we investigated a problem that happened during acid digestion experiment using conventional teflon vial or pressure bomb of BCR2 and GSP2 USGS rock standard materials. The results show that the measured concentrations of the elements like Cr, Ni, Zn, Ta, W in the BCR2 are different from the recommended values of USGS whereas those of the elements like Rb, Sr, Zr, Hf, Ta, W in the GSP2 are different from those values. Our experiment shows that defect of specific elements like Cr, Ni may happen during the sample digestion. Our results also indicate that the Cr, Ni, W, Zr, Hf, Ta concentration obtained based on an acid digestion of geological samples need to be careful in their geochemical interpretation.

• Journal of the Computational Structural Engineering Institute of Korea
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• 제31권5호
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• pp.251-258
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• 2018

In construction site, conventional methods such as jackhammer or explosive methods(dynamite) have been often used for the demolition of structures. Use of those methods are more carefully treated in environmentally and historically sensitive area. For those reasons, use of Soundless Chemical Demolition Agent(SCDA) is getting the spotlight. The SCDA is a powder which has expansive strength when it is mixed with water. In these Characteristics, SCDA can destroy the concrete or rock as it is poured into boreholes of the concrete or rock structures. However, there is no industrial standard for the use of SCDA effectively yet. In this study, experimental study to measure the expansive pressure was conducted depending on various boundary conditions such as waterproof, length of the steel pipe, submerged of steel pipe. Furthermore, computational analysis using damage plasticity model to predict the minimum required pressure of the SCDA for the concrete demolition depending on spacing between holes(k-factor) and compressive strength of the concrete was conducted. Obtained results indicates that water heat dissipation with submerged steel pipe shows the stable pressure for measuring the SCDA and hole distance(k-factor) is the most important factor for crack initiation of concrete.

• Tunnel and Underground Space
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• 제34권2호
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• pp.89-103
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• 2024

In the disposal environment, gases can be generated at the interface between canister and buffer due to various factors such as anaerobic corrosion, radiolysis, and microbial degradation. If the gas generation rate exceeds the diffusion rate, the gas within the buffer may compress, resulting in physical damage to the buffer due to the increased pore pressure. In particular, the rapid movement of gases, known as gas breakthroughs, through the dilatancy pathway formed during this process may lead to releasing radionuclide. Therefore, understanding these gas generation and movement mechanism is essential for the safety assessment of the disposal systems. In this study, an experimental apparatus for investigating gas migration within buffer was constructed based on a literature review. Subsequently, a gas injection experiment was conducted on a compacted bentonite block made of Bentonile WRK (Clariant Ltd.) powder. The results clearly demonstrated a sharp increase in stress and pressure typically observed at the onset of gas breakthrough within the buffer. Additionally, the range of stresses induced by the swelling phenomenon of the buffer, was 4.7 to 9.1 MPa. The apparent gas entry pressure was determined to be approximately 7.8 MPa. The equipment established in this study is expected to be utilized for various experiments aimed at building a database on the initial properties of buffer and the conditions during gas injection, contributing to understanding the gas migration phenomena.

• Journal of the Korean Society of Clothing and Textiles
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• 제34권12호
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• pp.1933-1946
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• 2010

This paper is a comparative analysis of the $19^{th}$ century practice of indigo dyes and dyeing in Korea and England. From over hundreds species of indigo plants in the world, it was dyer's knotweed and woad that were cultivated in Korea; however, the only indigo plant grown in England was woad. Indigo dye was produced in the form of damp indigo sediment (jeon) in Korea; however, imported indigo (as a main dye) and couched woad (as an additional dye) were indigo dyes used in England. There existed three kinds of indigo vats, the ice vat, ash-water vat, and indigo sediment (jeon) vat, in Korea. The fresh leaves of indigo were used for both the ice vat and ash-water vat. The ice vat was very convenient for preparation, but had a weakness in the inability to produce a very deep shade of blue. The ash-water vat and indigo sediment (jeon) vat were in use for producing a very deep shade of blue. The indigo sediment Goon) vat was employed presumably only by professional dyers. The indigo vat practiced in England was categorized into two types; one was woad-indigo vat, and the other was an indigo powder vat prepared by using imported indigo rock. There was a tendency to adopt different kinds of indigo vats according to the material to be dyed. The woad-indigo vat was employed for the dyeing of wool. A few of chemical vats with imported indigo were adopted, especially for the dyeing of cotton. Indigo dyers in 19th century Korea were differentiated from the rest of the dyers. They managed the growing of indigo plants as well as the production of indigo sediment (jeon). Woad dyers in 19th century England handled woolen cloth as well as worsted and woolen yarn in general. However, they sometimes dyed silk skein as well. They produced several colors such as black, blue, slates, grays, by using both woad and imported indigo.

• Journal of the Mineralogical Society of Korea
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• 제19권2호
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• pp.71-80
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• 2006

We examined the mineralogical composition of pyrite-bearing rocks by quantitative powder X-ray diffraction analysis using the matrix-flushing method and ROCKJOCK (a full pattern fitting computer program). The neutralization potential (NP) and acid generating potential (AP) were calculated on the basis of mineralogical compositions. The mineralogical AP was compared with the conventional AP calculated from bulk sulfur concentration to assess the applicability to the prediction of acid rock drainage(ARD). The pyrite content calculated by matrix-flushing method showed a high positive correlation($r^2$=0.95) with those by ROCKJOCK. The pyrite contents by matrix-flushing method was 1.45 times larger than those by ROCKJOCK. The pyrite content and mineralogical AP obtained by the matrix-flushing method had a better correlation($r^2$=0.98) with those by the total sulfur concentrations in the all samples except KB sample. The mineralogical NPs of YJ sample were 23.0 and 34.0(kg $CaCO_3$ equivalent per tonne) by matrix-flushing method and ROCKJOCK, respectively. The AP calculated by matrix-flushing method and ROCKJOCK program were 47% and 72% of those by the conventional ABA test. We hereby suggested that the quantitative analysis using XRD data can be applied to prediction of ARD. For more reliable calculation of the mineralogical NP and AP, other sulfide and carbonate minerals such as pyrrhotite, dolomite, ankerite, siderite, rhodochrosite which can affact the mineralogical NP and AP should be considered.

• Korean Journal of Soil Science and Fertilizer
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• 제27권3호
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• pp.158-167
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• 1994

The various weathering products derived from andesitic rocks in the Guweol mountain area of Pusan have been studied in order to investigate the occurrence, characteristics and evolutional trend of clay minerals in the weathered rock and soil using mainly X-ray powder diffraction method. Kaolinite and halloysite are very abundant in the weathered rocks and soils derived from andesitic rocks of this area. Also, $12{\AA}$- and $14{\AA}$-minerals occur in the considerable amount. $12{\AA}$-minerals have been identified as mica/vermiculite interlayer minerals showing the $25{\AA}$ basal reflection. Their crystal sizes are relatively big showing more than 10 micron in diameter. Two types of $14{\AA}$-mineral, which are vermiculite/smectite interlayer mineral and Al-vermiculite, have been observed. Kaolin minerais consist of kaolinite, $10{\AA}$ and $7{\AA}$ halloysite. Kaolinite relatively dominates in the strongly weathered soil of the area. In contrast with kaolinite. $12{\AA}$- and $14{\AA}$-minerals such as vermiculite/smectite and mica/vermiculite interlayer minerals tend to occur in the weakly to intermediately weathered products. Based on their occurrences, it strongly suggests that they are intermediate products in the course of the weathering process from the parent materials into the kaolin mineral.

• Journal of Conservation Science
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• 제18권
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• pp.63-74
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• 2006

All rock materials of the three storied stone pagoda in Seoakri were composed of light gray alkali granite with medium grained and developed with small mialolitic cavities. This stone pagoda is preserving almost archetype except the head part because there was repair work already. But, foundation, basement and roof rocks are serious state by microbial invasion such as lichens. Because there are tree and grass that cause direct effect to stone pagoda surrounding. Therefore, conservation treatment executed the primary dry cleaning and secondary wet cleaning treatment. Stone surface is partly not removed well such as lichens which part removed using cleansing device that use high temperature steam. Some treated part concrete and epoxy resin remove and retreatment with mixing talc and alkali granite powder to epoxy resin. Did color matching at mixing process of epoxy resin and fillers to properties with set the feel of a material. Also, drainage ditched to minimize inflow of rainwater fall from slope that is on the east of stone pagoda, tree and grass in stone pagoda surrounding wished to do remove and control occurrence of lichens hereafter minimizing moisture conteats.

• Journal of the Korean earth science society
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• 제26권7호
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• pp.674-682
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• 2005

The Samsung mine is located in Jeongsan-myeon, Cheongyang-gun, Chungcheongnam-do, and is produces sericite ores. The purpose of this study is to investigate the geology and mineralogy of sericite one and its host-rock together with the alteration processes and age of sericitization. Geological survey, polarizing microscopy, X-ray powder diffraction, electron microprobe analysis, X-ray fluorescent analysis, differential thermal analysis, and K/Ar isotope study have been employed for this study. The mine area is composed of Precambrian granite-gneiss and mica schist, and also Jurassic biotite granite. Serictization has occured within the granite-gneiss, and is interpreted to be formed by hydrothermal alteration. The sericite was formed by the breakdown of orthoclase, plagioclase, and biotite, respectively. With sericitization intensity increase, $SiO_2\;and\;Na_2O$ contents are decreased, while $Al_2O_3\;and\;K_2O$ increased. The formation age of sericite has been determined to be Jurassic, which corresponds well to the intrusion age of the biotite granite nearby.