• 한국정보컨버전스학회:학술대회논문집
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• 2008.06a
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• pp.99-102
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• 2008

Mineralogical studies of ore and alteration minerals have been conducted for the Hugo Dummett porphyry copper deposit. The Hugo Dummett porphyry copper gold deposit is located in the South Gobi region, Mongolia and currently being explored. This deposit divided into the Cu-rich Hugo Dummett South and the Cu-Au-rich Hugo Dummett North deposits. The Hugo Dummett deposits contain 1.08% copper(1.16 billion tonnes in total) and 0.23 g/t gold(Oyunchimeg et al., 2006). Copper-gold mineralization at these deposit are centered on a high-grade copper(typically>2.5%) and gold(0.5-2 g/t) zone of intense quartz stockwork veining. The high grade copper and gold zone is mainly within the Late Devonian quartz monzodiorite intrusions and augite basalt, also locally occurs in dacitic rocks. Intense quartz veining forms a lens up to 100 m wide hosted by augite basalt and partly by quartz monzodiorite. Although many explorations have been carried out, only a few scientific works were done in the Oyu Tolgoi mining area. Therefore the nature of copper-gold mineralization and orgin of the deposit is not fully understood. Copper-gold mineralization in the Hugo Dummett deposits occurs in dominantly quartz monzodiorite and minor augite basalt, dacitic rocks and locally biotite granodiorite. Chalcopyrite, pyrite, bornite, molybdenite, tennantite, tetrahedrite, enargite, sphalerite, chalcocite, covellite, eugenite, galena and gold occur as main ore minerals in the Hugo Dummett North and South deposits. These sulfides occur as: (1) a vague vein-like trail 1-3cm long and 2-3 mm wide, (2) minute, discontinuous cracks within quartz(micron scales), and (3) irregular blebs/spots(micron scales)and (4) disseminated within the sericite and plagioclase, commonly concentrated in the quartz. Sulfide minerals commonly display as a replacement, intergrown and minor exsolution texture in the both of the Hugo Dummet deposits.

• Journal of the Korean Society for Library and Information Science
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• v.48 no.3
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• pp.5-26
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• 2014

The legal deposit for the national library in all countries is the most important mean for acquiring the country's off-line and on-line publications. Because of many limitations of legal deposit system, however, the National Library of Korea does not properly collect the useful materials produced or manufactured in Korea. In order to solve this problem, the author analyzed the status of collection development by legal deposit and estimated the total amount of domestic publications. Based on the these results, author suggested five plans for strengthening the national collections in terms of the provisional 'deposit law', the further development and complementary of current legal deposit regulations (guidelines and standards), desirable amendments of the legal deposit provisions in library act, reasonable division of the deposit targets, and optimization strategies of acquisition scope by material types.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2001.11a
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• pp.29-30
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• 2001

This paper presents some results of plasma nitriding on hard chromium deposit. The substrates were C45 steel and $30~50{\;}\mu\textrm{m}$ of chromium deposit by electroplating was formed. Plasma nitriding was carried out in a plasma nitriding system with $95NH_3{\;}+{\;}SCH_4$ atmosphere at the pressure about 600 Pa and different temperature from $450^{\circ}C{\;}to{\;}720^{\circ}C$ for various time. Optical microscopy and X-ray diffraction were used to evaluate the characteristics of surface nitride layer formed by nitrogen diffusion from plasma atmosphere inward iCr coating and interface carbide layer formed by carbon diffusion from substrate outward Cr coating. The microhardness was measured using microhareness tester at the load of 100 gf. Corrosion resistance was evaluated using the potentiodynamic measurement in 3.5% NaG solution. A saturated calomel electrode (SiCE) was used as the reference electrode. Fig.1 shows the typical microstructures of top surface and cross-section for nitrided and unnitrided samples. Aaer plasma nitriding a sandwich structure was formed consisting of surface nitride layer, center chromium layer and interface carbide layer. The thickness of nitride and carbide layers was increased with the increase of processing temperature and time. Hardness reached about 1000Hv after nitriding while 900Hv for unnitrided hard chromium deposit. X-ray diffraction indicated that surface nitrided layer was a mixture of $Cr_2N$ and CrN at low temperature and erN at high temperature (Fig.2). Anodic polarization curves showed that plasma nitriding can greatly improve the corrosion resistance of chromium e1ectrodeposit. After plasma nitriding, the corrosion potential moved to noble direction and passive current density was lower by 1 to 4 orders of magnitude compared with chromium deposit(Fig.3).

• The Journal of the Petrological Society of Korea
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• v.14 no.3 s.41
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• pp.169-179
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• 2005

Acidic metavolcanic rocks distributed around the Chungju iron deposit show significantly high abundances of rare earth elements and high field strength elements. Relatively high ${\epsilon}_{Nd}$(0) values and lack of negative Nb anomaly suggest that assimilation of crustal material is not involved in their generation. They are plotted within the within-plate environment according the tectonic discrimination diagrams. Such geochemical characteristics are very similar to the acidic metavolcanic rocks of Munjuri Formation. They also show geochemical characteristics of Al-type magma of Eby (1992). All such diagnostic characters indicate differentiation of mantle-derived magma produced from the rift environment, related to the breakup of continent. In contrast to the alkali granites and the rare metal deposit both having age of c. 330 Ma, Sm-Nd isotopic data of the acidic metavolcanic rocks do not form well defined isochron. However, the alkali granites reveal low ${\epsilon}_{Nd}$(0) values, while the acidic metavolcanic rocks and the rare metal deposit both have significantly higher ${\epsilon}_{Nd}$(0) values. Considering such differences, we propose following generation hypothesis: The acidic metavolcanic rocks around Chungju iron deposit was erupted at 750 Ma as rest of the acidic metavolcanic rocks of Gyemyeongsan and Munjuri Formations. About 330 Ma ago, partial melting of existing Al-type igneous materials and some old crustal materials produced alkali granite. The rare metal deposit was also produced by redistribution of related materials within the acidic volcanics due to hydrothermal activities occurred at the same time. Sm-Nd isotopic systematics of the acidic metavolcanic rocks were disturbed during the regional metamorphic event at ca. 280 Ma.

• Economic and Environmental Geology
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• v.30 no.4
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• pp.379-393
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• 1997

Geology of the Zbezkazgan copper deposit in Kazhkstan is mainly composed of Permian and Carboniferous sedimenary rocks in which copper minerals are mainly contained in grey sandstone of Carboniferous age. There are 28 layers of copper ore bodies in Zbezkazgan suite. Thickness of the ore bodies ranges from one to 35 meters, grade of the crude ore ranges from 2 to 5 wt % Cu and the extension of the orebodies is 5 to 7 km. Microscopic study on specimens from the Zbezkazgan ore deposit has exposed clues to understand the origin of this deposit. Alternatively deposited grey sandstone and red sandstone are mainly composed of quartz and feldspar grains. A big difference between the grey sandstone and the red sandstone is in grain size, the former is larger than the latter. Chalcocites as main copper minerals have cemented through grain boundary. It is assumed that quartz, feldspar and copper were derived from granitoid in which copper mineralization had taken place before exposing to weathering. The chalcocites were precipitated by a sudden change of geochemical condition (Eh, pH, temperature, etc.) of fluid which had carried quartz, feldspars, copper ions and sulphate during formation of grey sandstones. The copper ions and sulphate were stable in fluid during sedimentation of oxidation environment, however, the copper ions were no more stable at the reduced environment and changed to stable forms to precipitate copper minerals by reaction of copper ions and hydrogen sulfides. This chemical precipitation of copper minerals in the sandstone attributes to the assumption of hydrothermal origin on this sedimentary origined deposit.

• Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
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• 2002.10a
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• pp.251-255
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• 2002

Eutrophic matters accumulated on the bottom of sea, river and lake cause red tide phenomenon in ocean and outbreak green algae in river and lake. Systems are developed to remove the noxious deposit. But the existing systems remove not only the eutrophic matters but also natural materials, sand, pebbles etc. that should remain at the bottom. This paper describes a new system that can safely, and economically take away the noxious deposit in underwater. High pressure water jet is used to induce vortices in the triangular suction section, and air-lifting pump to lift up the deposit. The mixture of the water and deposit is filtered through the drum filters. An under camera shows the under water situation along the moving direction of the system that is controlled by a remote operator. This remote controlled moving system obliterate the necessity of the diver that usually costs high. The experimental results show the effectiveness of the suggested system.

• Corrosion Science and Technology
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• v.11 no.6
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• pp.275-279
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• 2012

Ni-W alloy deposits have lately attracted the interest as an alternative surface treatment method for hard chromium electrodeposits because of higher wear resistance, hardness at high temperature, and corrosion resistance. This study deals with influences of process variables, such as electodeposition current density, plating temperature and pH, on the internal stress of Ni-W nanocrystalline deposits. The internal stress was increased with increasing the applied current density. With increasing applied current density, the grain size of the deposit decreases and concentration of hydrogen in the deposit increases. The subsequent release of the hydrogen results in shrinkage of the deposit and the introduction of tensile stress in the deposit. Consequently, for layers deposited at high current density, cracking occurs readily owing to high tensile stress value. By increasing the temperature of the electrodeposition from $60^{\circ}C$ to $80^{\circ}C$, the internal stress was decreased. It seems that an increase in the number of active ions overcoming the activation energy at elevated temperature caused a decline in the concentration polarization and surface diffusion. It decreased the level of hydrogen absorption due to the lessened hydrogen evolution reaction. Therefore, the lower level of hydrogen absorption degenerated the hydride on the surface of the electrode, resulting in the reduction of the internal stress of the deposits. By increasing the pH of the electrodeposition from 5.6 to 6.8, the internal stress in the deposits were slightly decreased. It is considered that the decrease in internal stess of deposits was due to supply of W complex compound in cathode surface, and hydrogen ion resulted from decrease of activity.

• Journal of Electrochemical Science and Technology
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• v.1 no.2
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• pp.117-120
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• 2010

Materials used as fuel cell electrode should be light, high conductive, high surface area for reaction, catalytic surface and uniformity of porous structure. Nickel is widely used in electrode materials because it itself has catalytic properties. When used as electrode materials, nickel of only a few im on the surface may be sufficient to conduct the catalytic role. To manufacture the nickel with porous structure, Electroless nickel plating on carbon fiber be conducted. Because electroless nickel plating is possible to do uniform coating on the surface of substrate with complex shape. Acidic bath and alkaline bathe were used in electroless nickel plating bath, and pH and temperature of bath were controlled. The rate of electroless plating in alkaline bath was faster than that in acidic bath. As increasing pH and temperature, the rate of electrolee plating was increased. The content of phosphorous in nickel deposit was higher in acidic bath than that in alkaline bath. As a result, the uniform nickel deposit on porous carbon fiber was conducted.

• Journal of the Korean Geographical Society
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• v.42 no.1 s.118
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• pp.15-26
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• 2007

This study aims to estimate the similarities of lacustrine deposits of lava-dammed Yeoncheon paleo-lake by geochemical analysis such as XRF, ICP-AES, and 14C and OSL age datings in Chugaryeong Rift Valley of Central Korea. OSL age of the lacustrine coastal deposit(YC1) is estimated as 0.11-0.13 Ma. It indicates that paleo-deposits may have remained during at least 20,000 years from 0.13 Ma The origin analysis of deposits were carried out by comparison between lacustrine mud layers($YC1{\sim}2$) and various geomorphic materials of vicinity As a result, the similarity of the origin is highest between the paleo-coastal alluvial deposit of Chatan River(YC8), and surface clay deposit of Jeongok lava plateau(YC9) Next higher similarity is between paleo-lacustrine bottom deposit(YC2) and west valley-side mountain slope colluvial materials(YC5). Another high similarities are among present Chatan River channel sediment(YC7), acustrine coastal deposit(YC1) and east valley-side mountain slope colluvial materials(YC4).

• Journal of the Korean institute of surface engineering
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• v.37 no.2
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• pp.80-85
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• 2004

Chromium-carbon (Cr-C) and chromium-carbon-phosphorus (Cr-C-P) alloy deposits using trivalent chromium sulfate baths containing potassium formate were prepared to study their current efficiency, hardness change and phase transformations behavior with heat treatment, respectively. The current efficiencies of Cr-C and Cr-C-P alloy deposits increase with increasing current density in the range of 15-35 A/dm$^2$. Carbon content of Cr-C and phosphorous of Cr-C-P layers decreases with increasing current density, whereas, the carbon content of Cr-C-P layer is almost constant with the current density. Cr-C deposit shows crystallization at $400^{\circ}C$ and has (Cr+Cr$_{ 23}$$C_{6}$) phases at $800^{\circ}C$. Cr-C-P deposit shows crystallization at $600^{\circ}C$ and has (Cr+Cr$_{23}$ $C_{6}$$+Cr_3$P) phases at $800^{\circ}C$. The hardness of Cr-C and Cr-C-P deposits after heating treatment for one hour increase up to Hv 1640 and Hv 1540 and decrease about Hv 820 and Hv 1270 with increasing annealing temperature in the range of $400～^{\circ}C$, respectively. The hardness change with annealing is due to the order of occurring of chromium crystallization, precipitation hardening effect, softening and grain growth with temperature. Less decrease of hardness of Cr-C-P deposit after annealing above $700^{\circ}C$ is related to continuous precipitation of $Cr_{23}$ $C_{6}$ and $Cr_3$P phases which retard grain growth at the temperature.