• Proceedings of the IEEK Conference
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• 2001.10a
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• pp.325-330
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• 2001

Shizhuyuan W-Mo-Bi-Ca $F_2$polymetallic ore is classified to the refractory one due to its complex property, fine dissemination and close association of minerals. Through several years of researches, in line with GY new mineral processing technology developed by Guangzhou Research Institute of Nonferrous Metals, in sulfide flotation circuit, an iso-flotability flowsheet is used to replace original overall bulk flotation flowsheet, and in tungsten flotation circuit, a new chelating type-GY reagent and a special pulp-conditioning system and a new technology of wolframite slime flotation are used to replace the traditional "Caustic Soda Method"$_{［1］}$, the metallurgical performance is greatly improved. Besides, GY New Method has created a favorable condition for comprehensive recovery of fluoride from tungsten flotation tailings. Notable economic benefit has been achieved.d.

• KSBB Journal
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• v.11 no.1
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• pp.115-123
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• 1996

Two kinds of mutants were isolated to clone a cluster of genes essential for zooglan biosynthesis. Zoogloea ramigera 115 strains produce capsular polysaccharide. To achieve conjugation in strain 115 and to facilitate recovery of product, a capsule non-forming strain was isolated via successive centrifugation and screening. The other kind of mutants devoid of or producing altered exopolysaccharides were obtained using classical transposon(Tn5) technique and screened for altered colony morphology and celluflour binding properties. Complementation of these mutants was achieved with Z. ramigera 115 slime gene library constructed in a broad host range cosmid vector and helper plasmid by triparental conjugation.

• The Korean Journal of Ecology
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• v.23 no.4
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• pp.331-337
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• 2000

Fourteen different taxa of dictyostelid cellular slime molds were recovered from the alpine and subalpine zone in Mt. Paektu. In subalpine zone, six species were recovered : Dictyostelium minutum, D. brefeldianum, D. crassicaule, D. capitatum, Polysphondylium solitarium and P. pallidum. One of these species which were isolated from the soils of Larix olgensis community exhibited several distinctive features which differed from the published species. This species was designated as a new species, Polysphondylium solitarium Kang et Chang, sp. nov. When cultivated at 22~24$^{\circ}C$ on low-nutrient agar media with Escherichia coli, Polysphondylium solitarium is distinguishable from other species by the following combination of features: (ⅰ) the sorocarps with vinaceous pigmentation; (ⅱ) pseudoplasmodia radial. usually centralized and rarely subdivided; (ⅲ) the various number of whorls; (ⅳ) the spores with unconsolidated and nonconspicuous polar granules. Also, we confirmed this new species by analyzing ribosomal DNA (ITS1, ITS2 and 5.8s DNA) sequences of P. solitarium and P. violaceum.

• Journal of Plant Biology
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• v.33 no.3
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• pp.159-168
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• 1990

The occurrence and distribution of cellular slime molds in major deciduous forests of South Korea were investigated. Ten species were isolated from the soils collected at ten sampling areas and cultured in hay infusion agar with E. coli. These include: Dictyostelium minutum Raper, Dictyostelium mucoroides Brefeld, Dictyostelium lacteum Van Tiegham, Dictyostelium polycephalum Raper, Dictyostelium fasciculutum Traub, Hohl and Cavender, Dictyostelium sp. Polysphondylium pallidum Olive, Polyshpondylium violaceum Brefeld, Copromyxellar sp. and Guttulinopsis vulgaris Olives. Among these species, Dictyostelium sp. and Copromyxellar sp. could not be identified. D. minutum and D. mucoroides occurred the most frequently in almost all the deciduous forests investigated in this study. Dictyostelium sp., D. fasciculutum and Copromyxella sp. occurred only in the north of the central region, but D. lacteum and D. polycephalum were found only in the south of that region. This indicates that distribution of these species may be affected by climate. The number of isolates per sampling site ranged from 2 to 6, averaging 4.3.

• Magazine of the Korea Concrete Institute
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• v.28 no.3
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• pp.18-22
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• 2016

• Proceedings of the Zoological Society Korea Conference
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• 1997.10b
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• pp.159.1-159
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• 1997

No Abstract, See Full Text

• Economic and Environmental Geology
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• v.33 no.2
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• pp.91-100
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• 2000

It has been more than ten years since Dukun mine was abandoned. Tailings of waste deposits and slime dumps in the abandoned Dukum mine have been left to be deserted for fifty years. The results of fifty years of neglecting are nothing short of major environmental problems. Slime dumps have been exposed to air and water in the mine over ten years and then soil profile has been formed well. Soil in the upper layer (A horizon) is the light gray color due to the leaching of cations. Soil in the lower layer (A2 horizon, 0.2∼0.3m)is tinted with reddish brown and yellowish brown color due to the development of iron oxides and iron hydroxides. Soil in the lower part of B horizon of (1.0∼3.0m) with the growth of copper and zinc oxides exposes to the bluish green, light blue, and dark gray. Ranging from 3m to 8m in depth, 85 samples were taken from 22 sampling sites with 50m intervals located on the slime dump area with hand auger and trench (open cut). As tailings was distributed, heavy metal elements extracted by the process of surface water and ground water move and disperse in to the hydrosphere. Waste dumps were distributed in and around the mine and water draining from those dumps be a potential source of contamination. Soils, thus, can be dispersed into downslope and downstream through wind and water by clastic movement. These materials may be deposited in another horizon if the water is withdrawn, or if the materials are precipitated as a result of differences in pH, or other conditions in deeper horizons. These were primarily associated with acid mine drainage. The characteristics and rate of release of acid mine drainage are influenced by various chemical and biological reactions at the source of acid generations. Prolonged extration of heavy metal elements has a detrimental effect on the agricultural land and residental area. Twenty soil samples were collected from the agricultural land in the area (0∼30 cm). Seventeen samples were also taken from the sediment in the stream running alongside the dumps. The dispersion patterns of heavy metal elements are as follows: The content of As ranged 2∼6 ppm in a horizon, 20∼125 ppm in B horizon with large amount of clay mineral is concentrated and the content of Cd ranged 1∼2 ppm in A horizon, 4∼22 ppm in B horizon. Like Cd, the content of As, Cu, Zn, Pb in B horizon is higher than that in A horizon (approximately 5∼100 times). When soil formation proceeds in stages, it is necessary to investicate the B horizon with the concentration of heavy metal and preventive measures will have to established.

• Resources Recycling
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• v.27 no.6
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• pp.23-29
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• 2018

Recently rapid economic growth and technological development have led to an increase in the generation of waste electrical and electronic equipment (WEEE). As the amount of electric and electronic waste generated increases, the importance of processing waste printed circuit boards (PCB) is also increasing. Various studies have been conducted to recycle various valuable metals contained in a waste PCB in an environmentally friendly and economical manner. To get anode slime containing Ag and Au, Anode copper prepared from PCB scraps was used by means of electro-refining. Ag and Au recovery was conducted by leaching, direct reduction, and ion exchange method. In the case of silver, the anode slime was leached at 3 M $HNO_3$, 100 g/L, $70^{\circ}C$, and Ag was recovered by precipitation, alkali dissolution, and reduction method. In the case of gold, the nitrate leaching residues of the anode slime was leached at 25% aqua regia, 200 g/L, $70^{\circ}C$, and Au was recovered by pH adjustment, ion exchange resin adsorption, desorption and reduction method. The purity of the obtained Au and Ag were confirmed to be 99.99%.

• Proceedings of the Zoological Society Korea Conference
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• 2001.10a
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• pp.152.2-152
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• 2001

No Abstract, See Full Text

• Proceedings of the Zoological Society Korea Conference
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• 1996.10a
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• pp.102.2-102
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• 1996

No Abstract, See Full Text