• Economic and Environmental Geology
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• v.12 no.2
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• pp.51-73
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• 1979

The zinc-lead deposits at the Yeonhwa I mine were investigated in terms of ore-forming geologic setting, structural style of ore control, geometry of individual orebodies, zoning, paragenesis and chemical composition of skarn minerals, as well as metal grades and ratios of selected orebodies. The Yeonhwa I mine is characterized by a large swarm of chimney type massive orebodies with thin skarn envelopes, boldly developed through a thick sequence of Pungchon Limestone, the overlying Hwajeol Formation, and the underlying Myobong Slate of Cambrian age. Nearly 20 orebodies of similar shape, but of varying size are arranged in a V-shaped pattern with northwest and northeast trends, clearly indicating an outstanding ore control by a conjugate system of fractures with these trends. Important orebodies are the Wolam 1, 2, 3, and 5 orebodies in the west, and the Namsan 1, 2, 3. and 5 orebodies in the east, among others. The Wolam 1 orebody, which was observed from the -360 level through the -240, -120, and 0 levels to the surface outcrops (totaling a vertical height of about 500m), shows a vertical variation in skarn mineralogy, ranging from pyroxene-garnet zone on the lower levels. through pyroxene (without garnet) zone on the intermediate levels, and finally to rhodochrosite vein on the upper levels and surface. Microprobe analyses of pyroxene and garnet on a total of 14 mineral grains revealed that pyroxenes are manganoan salitic in most samples, with downward increase of Fe and Mn, whereas garnets are highly andraditic, containing fractions of subordinate grossular with downward decrease of Fe. This indicates a reverse relationship of Fe-contents between pyroxene and garnet with depth. Ore minerals are major sphalerite, subordinate galena, and minor chalcopyrite. Sulfide gangue minerals include major pyrrhotite, and minor pyrite and marcasite of later age. Two types of variational trends in metal grades and ratios with depth are present on the plots of assay data from the Wolam orebodies: one is a steady upward increase in Pb, Zn, and Pb:Zn ratios, with a terminal decline at the top of orebody: the other is an irregular or sinusoidal change. The former is characteristic of chimney-type orebodies, whereas the latter is of vein· shaped orebodies. The Pb grades show large variations among orebodies and from level to level, whereas the Zn grades are relatively constand or less variable.

• Economic and Environmental Geology
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• v.41 no.1
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• pp.93-113
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• 2008

This study presents petrochemistry and $^{40}Ar/^{39}Ar$ absolute ages of subsurface volcanic rock cores from twenty(20) boreholes in the eastern lowland (altitude loom below) of Jeju Island, Handeong-Jongdal-Udo-Susan-Samdal-Hacheon areas, and discusses topography and volcanism in the area. The subsurface volcanic rock cores are mainly basalts in composition with minor tholeiitic andesites and basaltic trachyandesites. Sequences of intercalated tholeiitic, transitional and alkalic lavas suggest that tholeiitic and transitional to alkalic lavas must have erupted contemporaneously. Especially, occurrences of trachybasalts and basaltic trachyandesites at the bases in the area imply that the volcanism in the area was initiated with slightly differentiated alkaline magma activity. The $^{40}Ar/^{39}Ar$ absolute ages of the subsurface volcanic rock cores range from $526{\pm}23ka\;to\;38{\pm}4Ka$. The lava-forming Hawaiian volcanic activities of the eastern lowland can be divided into five sequences on the basis of sediment distribution, whole rock geochemistry and $^{40}Ar/^{39}Ar$ absolute ages of the subsurface volcanic rock cores; stage I-U$(550{\sim}400Ka)$, stage II$(400{\sim}300Ka)$ and stage III$(300{\sim}200Ka)$ during syn-depositional stage of Seoguipo Formation, and stage IV$(200{\sim}100Ka)$ and stage V(younger than 100Ka) during post-depositional stage. In the eastern lowland of Jeju Island, compositional variations and local occurrences of the subsurface volcanic rocks as well as existences of various intercalated sediment layers (including hydrovolcanogenic clasts) suggest that the volcanism must have continued for long time intermittently and that the land has been progressively glowed from inland to coast by volcanic activities and sedimentation. It reveals that the subsurface volcanic rocks in the eastern lowland of Jeju Island must have erupted during relatively younger than 200Ka of stages IV and V. The results of this study are partly in contrast with those of previous studies. This study stresses the need that previous reported volcanic activities in Jeju Island based on K-Ar ages of volcanic rocks should be carefully reviewed, and that stratigraphic correlation from boreholes should be conducted by quantitative criteria combined with petrography and petrochemstry as well as radiometric studies of volcanic rock cores.

• Journal of Soil and Groundwater Environment
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• v.7 no.4
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• pp.68-76
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• 2002

In this study, we have investigated the geochemical behavior and fate of heavy metals in acid rock drainage (ARD). The ARD was collected from the area of the former Dongrae pyrophyllite mine. The Dongrae Creek waters were strongly acidic (pH : 2.3~4.2) and contained high concentrations of $SO_4$, Al, Fe, Mn, Pb, Cu, Zn, and Cd, due to the influence of ARD generated from weathering of pyrite-rich pyrophyllite ores. However, the water quality gradually improved as the water flows downstream. In view of the change of mole fractions of dissolved Fe, Al and Mn, the generated ARD was initially both Fe- and AA-ich but progressively evolved to more Al-rich toward the confluence with the uncontaminated Suyoung River. As the AR3 (pH 2.3) mixed with the uncontaminated waters (pH 6.5), the pH increased up to 4.2, which caused precipitation of $SO_4$-rich Fe hydroxysulfate as a red-colored, massive ferricrete precipitate throughout the Dongrae Creek. Accompanying the precipitation of ferricrete, the Dongrae Creek water progressively changed to more Al-rich toward downstream sites. At the mouth of the Dongrae Creek, it (pH 3.4) mixed with the Suyoung River (pH 6.9), where pH increased to 5.7, causing precipitation of Al hydroxysulfate (white precipitates). Neutralization of the ARD-contaminated waters in the laboratory caused the successive formation of Fe precipitates at pH<3.5 and Al precipitates at higher pH (4~6). Manganese compounds were precipitated at pH>6. The removal of trace metals was dependent on the precipitation of these compounds, which acted as sorbents. The pHs for 50% sorption ($pH_{50}$) in Fe-rich and Al-rich waters were respectively 3.2 and 4.5 for Pb, 4.5 and 5.8 for Cu, 5.2 and 7.4 for Cd, and 5.8 and 7.0 for Zn. This indicates that the trace metals were sorbed preferentially with increasing pH in the general order of Pb, Cu, Cd, and Zn and that the sorption of trace metals in Al-rich water occurred at higher pH than those in Fe-rich water. The results of this study demonstrated that the partitioning of trace metals in ARD is not only a function of pH, but also depends on the chemical composition of the water.

• Korean Journal of Food Science and Technology
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• v.25 no.5
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• pp.468-474
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• 1993

A dehydrating sheet comprises polymeric water absorber. which are packed in a semipermeable cellophane film bag allowing selective permeation of water. This sheet dehydration is quite different from conventional drying method such as sun drying, hot-air blast drying and cold air blast drying in a sense that samples are dried without heat treatment. As a part of the studies to develope a new processing method for effective utilization of dark muscle fishes, the preparation of a good quality salted and semi-dried mackerel by the dehydrating sheet was attempted. The dehydration time for preparation of a salted and semi-dried mackerels containing approximately equal moisture content were revealed $180{\sim}510min$ in conventional drying method and $90{\sim}160min$ in this sheet dehydration, respectively. The moisture and histamine contents of those salted and semi-dried mackerels were $59.4{\sim}62.4%$ and $2.5{\sim}3.6 mg/100g$, respectively. The changes in peroxide value, fatty acid composition, brown pigment formation, myofibrillar protein solubility and Ca-ATPase activity during processing of the salted and semi-dried mackerel prepared by the sheet dehydration were more lower than those of products prepared by conventional drying methods. Therefore, these result showed that the quality of a salted and semi-dried mackerel prepared by the sheet dehydration was imperial to that of those products by conventional drying method.

• Korean Journal of Food Science and Technology
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• v.35 no.6
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• pp.1079-1085
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• 2003

Modified atmosphere packaging was applied to oyster mushrooms (Pleurotus ostreatus) to study the effect of storage temperatures and packaging materialso. Whole mushrooms (200g) were package with polyethylene film $(PE,\;60{\mu}m\;thickness)$, ethylene vinyl acetate (EVA), or ceramic film (containing 5% zeolite) and stored at 0, 5, 10 and $20^{\circ}C$. Weight loss, color, firmness, gas composition $(O_2,\;CO_2)$ inside the film package and ethanol content in the tissue of MA packaged mushrooms were examined. Mushroom that were packed unwrapped in a conventional hardboard box (2 kg) lost marketability at a very early stage of storage due to weight loss, shrinkage, browning, and spore formation. During storage, film packaging prevented or retarded the deterioration of the mushrooms in the aspects of appearance, texture, and discoloration. Firmness slightly decreased with storage time. Total color difference was much higher in the control than in the film-packaged mushroom and rapidly increased at the early of storage. Correlation analysis showed a high correlation between total color difference and b values. These results were characterized by the reduced respiration rate resulting from elevated carbon dioxide and reduced oxygen levels in the package. At all storage temperatures, ethanol content in the tissue increased slightly at the early part of storage and rose considerably towards the end of the storage period. Ethanol content in the oyster mushrooms was higher in the stipe than in pileus tissues. The shelf life of the oyster mushrooms was about $8{\sim}11$ days at $0^{\circ}C$, about $4{\sim}6$ day at $5^{\circ}C$, about $2{\sim}3$ days at $10^{\circ}C$, and about $1{\sim}2$ days at $20^{\circ}C$.

• Applied Biological Chemistry
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• v.44 no.4
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• pp.224-229
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• 2001

This study was carried out to examine the quality stability of powdered soup using powder from oyster wash water (PSW). To compare the quality stability, powdered soup from oyster hot-water extracts (PSE) was also prepared by mixing hot-water extract powder (15 g), table salt (5 g), cream powder (19 g), milk replacer (12 g), wheat flour (20 g), corn flour (15 g), starch (5 g), glucose (7.5 g), and onion powder (1.5 g). In preparing PSW, powder from oyster wash water, instead of powder from oyster hot-water extracts, was added and other additives were the same proportion as PSE. The PSW and PSE were packed with laminated film bag (OPP,$20\;{\mu}m$; PE, $20{\mu}m$; paper, $45\;g/m^3$; PE, $20\;{\mu}m$; Al, $7\;{\mu}m$; PE, $20\;{\mu}m$), and then stored at ambient temperature for 12 months. The moisture content, water activity, peroxide value, and fatty acid composition showed little changes during storage of the PSW, The pH, volatile basic nitrogen content, and brown pigment formation increased slightly, while white index decreased slightly during storage of PSW. No significant difference was observed in the changes of food components between PSW and PSE during storage. According to a sensory evaluation, the change in quality of PSW was negligible during 12 months of storage. From the results of the chemical experiment and sensory evaluation, PSW packed with laminated film bag (OPP, $20\;{\mu}m$; PE, $20\;{\mu}m$; paper, $45\;g/{\mu}m$; PE, $20\;{\mu}m$) was revealed to be preserved in good quality during 12 months of storage.

• Journal of the Korean Magnetics Society
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• v.15 no.1
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• pp.42-47
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• 2005

Nanocrystalline Nd-Fe-B powder was synthesized by a new thermochemical process that combined with past reduction-diffusion process and spray-dry process. In this process, Ca reduction process is vary important due to formation of hard magnetic$Nd_{2}Fe_{14}B$ phase from various oxides by Ca powder. Therefore, the final products are essentially affected a shape, size, and composition etc. of the Ca reduced powders. Ca reduction was performed to way that raw powders just mixed with Ca powder in proper ratio unlike to compress into compact. The powders after mixture-type Ca reduction mainly composited with $Nd_{2}Fe_{14}B$ phase even relativily low reaction temperature ($800^{\circ}C$) and all particle size of powder were distributed less than 1 ${\mu}m$ except for powder after Ca oxides as magnetic properties of powders after cake-type Ca reduction, with the consequence that high magnetic properties has been expected. The magnetic properties of powders prepared by mixture-type Ca ruduction, with the conseqence that high magnatic properties has been expected. The magnetic properties of powders prepared by mixture-type Ca reduction process showed $_iH_c$ = 5.9 kOe, $B_r$ = 5.5 kG, (BH)max = $Nd_{2}Fe_{14}B{\to}Nd_{2}Fe_{17}B$ decomposition by violent exothermic reaction during washing.

• Economic and Environmental Geology
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• v.44 no.4
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• pp.273-288
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• 2011

Chon-Ashuu copper mining claim area is located, in terms of the geotectonic setting, in the northern part of the suture line which is bounded with the marginal part of Issik-kul micro-continent on the southern part of North Tien-Shan terrane. The geological blocks of Chon-Ashuu districts belong to the southern tip of Kazakhstan orocline. The rock formation of this area are composed of the continental crust or/and arc collage and the paleo-continental fragments-accretionary wedge complex of pre-Altaid orogenic materials. ASI(Alumina Saturation Index) of Paleozoic plutonic rocks in Chon-Ashuu area belong to the peraluminous and metaluminous rocks which were generated from fractional crystallization of Island and volcanic arc crusts in syn-post collisional plate. The geology of the ChonAshuu area consists of upper Proterozoic and Paleozoic rock formations. According to Harker variation diagrams for Chon-Ashuu arenaceous sedimentary rocks, the silty sandstone of Chon-Ashuu area showing the mineralogical immaturity were derived from Island arc or the marginal environments of active continent in Cambro-Carboniferous period. Numerous intrusive rocks of Chon-Ashuu area are distributed along north east trending tectonic structures and are bounded on four sides by the conjugate pattern. The most common type of the plutonic rocks are granodiorite and monzodiorite. According to the molecular normative An-Ab-Or composition (Barker, 1979), the plutonic rocks in Chon-Ashuu area are classified into tonalite - trondhjemite - granodiorite (TTG) series which are an aggregation of rocks which is the country rock of copper mineralization, that are formed by melting of hydrous mafic crust at high pressure.

• Economic and Environmental Geology
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• v.34 no.6
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• pp.507-522
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• 2001

At the Tongyeong mine, quartz, rhodochrosite (kutnahorite), muscovite, illite, pyrite, galena, chalcopyrite. sphalerite, acanthite, and hessite are the principal vein minerals. They were deposited under epithermal conditions in two stages. Ore mineral assemblages and associated gangue phases in stage can be clearly divided into two general associations: an early cycle (band) that appeared with introduction of most of the sulfides and electrum, and a later cycle in which base metal and carbonate-bearing assemblages (mostly rhodochrosite) became dominant. Tellurides and some electrum occur as small rounded grains within subhedral-to euhedral pyrite or anhedral galena in stageII. Sulfide mineralization is zoned from pyrite to galena and sphalerite. We have used computer modeling to simulate formation of four stages of vein genesis. The reaction of a single fluid with andesite host rock at 28$0^{\circ}C$, isobaric cooling of a single fluid from 26$0^{\circ}C$ to 12$0^{\circ}C$, and boiling and mixing of a fluid with both decreasing pressure and temperature were studied using the CHILLER program. Calculations show that the precipitation of alteration minerals is due to fluid-andesite interaction as temperature drops. Speciation calculations confirm that the hydrothermal fluids with moderately high salinities and pH 5.7 (acid), were capable of transporting significant quantities of base metals. The abundance of gold in fluid depends critically on the ratio of total base metals and iron to sulfide in the aqueous phase because gold is transported as an Au(HS)$_2$- complex, which is sensitive to sulfide activity. Modeling results for Tongyeong mineralization show strong influence of shallow hydrogenic processes such as boiling and fluid mixing. The variable handing in stageII mineralization is best explained by maltiple boilings of hydrothermal fluid followed by lateral mixing of the fluid with overlying diluted, steam-heated ground water. The degree of similarity of calculated mineral assemblages and observed electrum composition and field relationships shows the utility of the numerical simulation method in identifying chemical processes that accompany boiling and mixing in Te-bearing Au-Ag system. This has been applied in models to narrow the search area for epithermal ores.

• Journal of Embryo Transfer
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• v.21 no.2
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• pp.157-162
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• 2006

It is well known that unidentified factors in sera, hormones and growth factors promote the proliferation of granulosa cells and nuclear maturation of bovine COCs (cumulus oocytes complexes) in vitro. Attempts had been developed the simple composition of culture media and similar system to in vivo conditions has been applied. In the present study, we investigated the effect of FGF (fibroblast growth factor) on in vitro maturation and in vitro development of Hanwoo COCs. When the COCs were matured in HPM 199 (Inst. of Functional peptide, Japan) containing 0.1, 1 and 10 ng/ml FGF for 24 hr, maturation rates to metaphase II ($70.0{\sim}75.0%$) were significantly higher (p<0.05) than that of control group (0 ng/ml FGF, 37.5%). When matured COCs with FGF were cultured in maturation medium after in vitro fertilization, developmental rates to blastocysts were 9.5, 0 and 2.9%, respectively, compared to 25.0% of the control group (p<0.05). When the matured COCs with FGF were cultured in HPM 199 (IFP971, Inst. of Functional peptide, Japan) containing 10% FBS, 0.8% BSA or 0.1% PVA (polyvinyl alcohol), the blastocyst formation rates were 12.4, 12.8 and 8.5%, respectively, while the rates of matured COCs with FGF and cultured with IVMD and IVD (Inst. of Functional peptide, Japan) without serum were 38.4% and 34.8%, respectively (p<0.05). These results suggested that FGF is available for in vitro maturation of bovine COCs and is not suitable for in vitro development, but further investigation would be need for finding the synergistic autocrine/paracrine fashion of other growth factors in early bovine embryo development.