• Economic and Environmental Geology
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• v.27 no.6
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• pp.523-535
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• 1994

The strata-bound type iron ore bodies in the Chungju mine are interbedded with metamorphic rocks which are intruded by Mesozoic granitic rocks. The iron ore deposit occurs as layer or lens shape which are concordant with the metamorphic rocks. The iron ore is classified into banded and massive types based on the mode of texture and occurrence. Grain size and iron-oxides tend to become coarser toward massive ore than banded ore. Banded ores commonly contain internal layers defined by alternating magnetite- rich, hematite-rich, magnetite-hematite, and quartz-rich mesobands. The banded iron ore consists of hematite, magnetite, quartz, feldspar, and minor amounts of biotite, muscovite, chlorite, carbonates, epidote, allanite, and zircon. Massive ores which are characterized by high magnetite content occur in contact of granitic rocks. The massive iron ores consist mostly of magnetite and quartz, with minor amounts of hematite, pyrite, microcline, biotite, muscovite, chlorite, carbonates, epidote, allanite and zircon. Magnetite from banded and massive ores is almost pure $Fe_3O_4$ in composition, including 0.14 to 0.27 wt.% MnO and 0.10 to 0.15 wt.% MnO, respectively. Hematite of the ore contains 0.87 to 1.27 wt.% $TiO_2$ in banded ore and 3.44 to 6.96 wt.% $TiO_2$ in massive ore, respectively. Biotite shows a little compositional variation depending on ore types. Biotite of the banded ore has lower FeO, $TiO_2$ and $Al_2O_3$, and higher MgO and $SiO_2$ than the massive ore. The modes of occurrence and petrography of ore implies that massive ores might have been formed either under more reducing environments or higher temperature condition than banded ore. Banded ores might represent early episode of iron enrichment due to regional metamorphism. Massive ores might be related to the contact metamorphism resulting from late granitic intrusion.

• The Korean Journal of Ecology
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• v.23 no.3
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• pp.281-291
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• 2000

The objectives of this study were to classify quantitatively vegetational types of P. densiflora for. erecta forest. The results were summarized as follows. 1) According to the canonical correspondence analysis(CCA), variables such as topography, altitude, available P/sub 2/O/sub 5/, and Mg/sup 2＋/were highly correlated on three axes. Based on the correlations between vegetation units and environmental factors, Rhododendron micranthum community tended to be more distributed in the such situations of high altitude, upper topography, high C/N ratio, low level of Mg/sup 2＋/and Ca/sup 2＋/. Vaccinium koreanum community tended to be more distributed in the such conditions of high altitude, upper topography, high level of Ca/sup 2＋/and Ma/sup 2＋/. 2) According to the results of importance value analysis, Tree layer and Subtree layer in study areas showed high Ⅳ along with P. densiflora for. erecta, Quercus mongonlica, Q. variabilis, Q. serrata, Fraxinus rhychophylla and shrub layer indicated that Ⅳ of P. densiflora for, erecta in Sokwang-ri area was higher than those of the other areas. Therefore, it was considered that P. densiflora for. erecta forest of Sokwang-ri area could be naturally regenerated. 3) According to results of species diversity, the species diversity of Uljin region showed the least low value as 0.6622, other regions appeared about 0.7. In the diversity by vegetation types, Acer pseudosieboldianum community showed high value. 4) According to the analysis of community similarity, Sokwang-Ri region was lowly correlated with Uljin region, while the index among the other areas appeared above 0.6. 5) According to the analysis of interspecific association, it was divided into 2 groups. The species of first group were mainly involved in character species, and the species of second group were involved in differential species groups.

• Economic and Environmental Geology
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• v.29 no.4
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• pp.421-428
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• 1996

The occurrence, optical property, chemical composition, crystal structure and formation environments of the phillipsite within deep-sea manganese nodules were systematically investigated in this study. Phillipsite in manganese nodules occurs in nucleus of nodules along with consolidated bottom sediments, weathered volcanic debris, and interstitial grains in the each layer of manganese encrusts. Phillipsite is predominantly pseudomorphs of volcanic shards, and occurs as white to pale yellow in color lath-shaped and equant crystals. These show aggregations of prismatic, blocky, and bladed of 2 to $20{\mu}m$ long, and 2 to $5{\mu}m$ thick. The simplified average chemical formula of phillipsite is $({Ca_{0.1}Mg_{0.3}Na_{1.1}K_{1.5}})_3{(Fe_{0.3}Al_{4.2}Si_{11.8})O_{32}{\cdot}10H_2O}$ with a very siliceous and alkalic. The $Si/(Al+Fe^{+3})$ ratio is 2.37 to 2.78 and alkalis greatly exceed the divalent exchangeable cations, and Na/K ratio is 0.59 to 0.81. The phillipsite is monoclinic ($P2_l/m$) with the unit-cell parameters, $a=10.005{\AA}$, $b=14.129{\AA}$, $c=8.686{\AA}$, ${\beta}=124.35^{\circ}$, and $V=1013.6{\AA}^3$. Phillipsites in manganese nodules formed apparently authigenically at a temperature less than $10^{\circ}C$, and they crystallized at a pressure of less than 0.7 kb, and pH of about 8 in deep-sea environments.

• Journal of the Korean Wood Science and Technology
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• v.28 no.4
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• pp.41-50
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• 2000

Cement-bonded particleboard is being used as outdoor siding material all over the world, because this composite particularly bears a light weight, high resistance against fire, decay, and crack by cyclic freezing and thawing, anti-shock property, and strength enhancement. Construction systems are currently changing into a frame-building style and wooden houses are being constructed with prefabrication type. Therefore, they require a more durability at outdoor-exposed sides. In this study, the cement hydration property for Korean pine particle, Japanese larch particle and face- and middle layer particles (designated as PB particle below) used in Korean particleboard-manufacturing company was investigated, and the rapid manufacturing characteristics of cement-bonded particleboard by supercritical $CO_2$ curing was evaluated. Korean pine flour showed a good hydration property, however, larch flour showed a bad one. PB particle had a better hydration property than larch flour. The addition of $Na_2SiO_3$ indicated a negative effect on hydration, however, $MgCl_2$ had a positive one. Curing by supercritical $CO_2$ fluid gave a conspicuous enhancement in the performances of cement-bonded particleboards compared to conventional curing. $MgCl_2$ 3%-added PB particle had the highest properties, and $MgCl_2$ 1%-added Korean pine particle had the second class with the conditions of cement/wood ratio of 2.7, a small fraction-screened particle and supercritical curing. On the contrary, the composition of non-hammermilled or large fraction-screened particle at cement/wood ratio of 2.2 was poorer. Also, the feasibility for actual use of 3%-added, small PB particle-screened fraction was greatest of all the conventional curing treatments. Relative superiority of supercritical curing vs. conventional curing at dimensional stability was not so apparent as in strength properties. Through the thermogravimetric analysis, it was ascertained that the peak of a component $CaCO_3$ was highest, and the two weak peaks of calcium silicate hydrate and ettringite and $Ca(OH)_2$ were present in supercritical treatment. Accordingly, it was inferred that the increased formation of carbonates in board contributes to strength enhancement.

• The Korean Journal of Mycology
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• v.14 no.1
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• pp.61-70
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• 1986

Sterigmatocystin bears a close structural relationship to aflatoxin $B_1$ and is a carcinogenic compound that has been shown to affect various species of experimental animals. Reaction and toxicity of sterigmatocystin in the artificial gastric juice were investigated. Sterigmatocystin was degraded in artificial gastric juice and extracted by the method of A.O.A.C. After cleaned up by silica gel column chromatography, this substance was detected and characterized by thin layer chromatography, UV, IR and mass spectra. It showed $R{\mathcal{f}}$ 0.4 and brick-red color by TLC. Especially, in the mass spectrum of it, fragment peak at m/e 327 was due to the loss of the $-CH_3$ and $-H_2O$, fragment peak at m/e 341 was due to the loss of the $H_2O$ and $-H^+$, and fragment peak at m/e 239 was due to the loss of the 2-chloro-tetrahydrofuran and methyl group from the parent molecule. Therefore, a degraded substance of sterigmatocystin reacted in artificial gastric juice (Sub. K) was estimated with additional formation of hydrochloric acid. In four-day-old chicken embryos, the mean lethal dose $(LD_{50})$ was $140\;{\mu}g/egg$, and 90 to 100% of the embryos were killed with 1 mg/egg. This $LD_{50}$ $140\;{\mu}g/egg$ compared with an $LD_{50}$ $14.69\;{\mu}g/egg$ for sterigmatocystin (acute toxicity) showed the substance to be much less toxic than sterigmatocystin.

• Journal of the Mineralogical Society of Korea
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• v.4 no.2
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• pp.129-140
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• 1991

Two illite polytypes, 2M1 and 1Md, have been identified from the sericite deposits of the Bobae mine, Kimhae, Kyungsangnam-do. Each polytype has characteristic grain size, chemical composition, and occurrence. 2M1 illite occurs predominantly in the sericitic alteration zone, while 1Md illite occurs predominantly in the propylitic alteration zone, implying that the former was formed in the higher temperature than the latter. Illites can be subdivided into two types based on their crystal sizes;(1) the $\mu\textrm{m}$-sized illite which is below 0.01mm(100$\mu\textrm{m}$) in size and consists of 2M1 and 1Md type, (2) the mm-sized illite which is above 0.01mm in size and consists only of 2M1 type. Especially illite below 1$\mu\textrm{m}$ is premominantly of 1Md type. Therefore, it seems likely that illite crystal size is to some extent related to the polytype. XRD data show that there is no interstratified layer in illites regardless of the crystal size and polytype. Activity of muscovite component of the $\mu\textrm{m}$-sized illite is 0.843 while that of the mm-sized illite is 0.790. However, the latter is more similar to muscovite in crystal structure than the former is. The mm-sized illite has less Al and more Kthan the $\mu\textrm{m}$-sized illite. In both illites, Si contents show a positive relation to octahedral Mg. Fluid inclusion study and mineral association show that the formation temperature of illite is $270-330^{\circ}C$. The major chemical processes leading to the formation of sericitic deposit as well as the alteration zones are the leaching of SiO2 from the country rock and the addition of Al2O3 and K2O into the sericitic ores.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2001.02a
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• pp.14-28
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• 2001

As basic study for purpose bioremedation in oil-contaminated environment, Primarily, we isolated biosurfactant producer- strains utilized of oil-agar plate, and measured surface tension and emulsifying activity. We investigated in oil-contaminated soil and sea water. In this laboratory, Pseudomonas sp. EL-012S strain isolated from oil-contaminated soil was able to product novel biosurfactant under the optimal culture condition. Its condition was n-hexadecane 2.0%, NH$_4$NO$_3$0.4%, Na$_2$HPO$_4$0.6%, KH$_2$PO$_4$0.4%, MgSO$_4$.7$H_2O$ 0.02%, CaCl$_2$.2$H_2O$ 0.001%, FeSO.7$H_2O$ 0.001%, initial pH 7.0 and aeration at 3$0^{\circ}C$, respectively. This biosurfactant was produced in both late-exponential and early-stationary phase. The biosurfactant from Pseudomonas sp. EL-012S was composed of carbohydrate, lipid and protein. The purified-biosurfactant was examined two (biosurfactant type I, II) with the silica gel G60 column chromatography and the purified biosurfactant confirmed thin layer chromatography, high performed liquid chromatography and gas chromatography. The biosurfactant type I involved in carbohydrate-lipid-protein characteristics lowered surface tension of water to 27dyne/cm and interfacial tension 4.5dyne/cm aginst to n-hexadecane and the biosurfactant type B involved in carbohydrate lipid characteristics lowered surface tension of water to 30dyne/cm and interfacial tension 8dyne/cm against to n-hexadecane. Specially type I had the properties such as strong emulsifying activity, emulsion stability, pH-stability, thermo-stability, high cleaning activity and forming ability.

• Journal of The Korean Society of Grassland and Forage Science
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• v.18 no.3
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• pp.223-232
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• 1998

The main experiment related to this report was undertaken to assess the effects of two rates of $Ca(OH)_2$ (0, 250 kg/10a only at establishment) and five rates of $N-P_20_5-K_20$ (0-0-0, 0-10-10, 6-15-15, 12-20-20, 24-25-20 kg/10a/year) on the pasture establishment, forage yield and quality, and vegetation etc. After this 10-year main e experiment pasture had been used to assess the effects of the above treaments on the soil characteristics in oversown hilly pasture of a grass-clover sward. soil properties of mutual ratios of exchangeable cations at d different soil depth, and the visible characteristics of soil conservation obtained are summarized as follows; 1. Compared with the properties of soil fertility and the level for the likelihood grass tetany, the mutual ratios of exchangeable cations in soils; Ca:Mg:K(% of CEC), Ca:Mg:K(K=I), $K/\sqrt{Ca+Mg}$, Mg/K, K/Mg, and Ca/Mg, were discussed at different soil depth. Before and after experiment, these ratios were generally unbalance and unsuitable, and were rather worsened in the order of Mg>Ca>K under the conditions of liming and NPK fertilization without Mg. 2. The ratios of Ca and Ca/Mg were increaby liming, whereas it of $K/\sqrt{Ca+Mg}$ was redused. The ratios of K and $K/\sqrt{Ca+Mg}$ in control and the heavy fertillization of NPK(especially N) were rather lowered than those in the low and medium fertilizations of NPK. 3. The prperties of consevation were closely related with the forage productivity/vegetation rates, as affected by liming and the application rates of NPK. In control of NPK, It was shown to be the worst soil conservation; severly eroded(3rd grade), exporsure of subsoil, redish brown in soil colour, and 18.8% of cobble and stony in covering rate. 4. The improvement of soil conservation was greatly enhanced by increasing the NPK rate. In the medium and heavy fertilizations of NPK, it was shown to be the favorable improvement of soil conservation; slightly eroded(lst grade), covered with humus layer/grass residues in surface soil, dark brown in surface soil colour, under 1% of cobble and stony in covering rate. The increasing of legume yield/vegetation rate by liming rather enhanced the soil conservation of grassland.

• Korean Journal of Soil Science and Fertilizer
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• v.34 no.3
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• pp.178-184
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• 2001

A study was carried out to investigate the effect of rice bran and charcoal meal application on growth in rice and bacterial population in paddy soil. Four different treatments were applied ; at whole layer placement of rice bran 1.8Mg/ha(1.8WR), surface of rice bran 1.8Mg/ha(1.8SR), charcoal meal 3.0Mg/ha(3.00M), and combined rice bran 1.8Mg/ha and charcoal meal 3.0Mg/ha (1.8R+3.0C) through field experiment. $NH_4-N$ and $NO_3-N$ in soil were high in the application of 1.8SR and 1.8R+3.0C until heading stage after rice bran application. Amount of nitrogen absorbed by rice plant were the highest in application of 1.8R+3.0C, and the lowest in application of 3.0CM. Rice yield was no differences among treatments. A number of total aerobic bacteria were the highest in application of 1.8R+3.0C at panicle formation stage of rice. Cellulose decomposers were high in application of 1.8SR at tillering stage and in application of 1.8R+3.0C at harvesting stage. The microorganisms of ammonia-oxidizing and denitrifying bacteria showed higher number in the application of 1.8R+3.0C and 1.8SR at tillering stage than heading stage. Azotobacter had tendency to decreased with the passage of time, but increased when rice bran was added. Athiorhodacea were numerous in the application of 1.8WR, but a few in the application of 3.0CM through growing period of rice plant.

• Journal of Electrical Engineering and Technology
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• v.13 no.4
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• pp.1638-1643
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• 2018

Multi-layer ceramic capacitors as decoupling capacitor were fabricated by dielectric composition with a high dielectric constant. The fabricated decoupling capacitors were embedded in the PCB of the 10G RF transceiver module and evaluated for the characteristics of electrical noise by the level of AC input voltage. In order to further improve the electrical properties of the $BaTiO_3$ based composite, glass frit, MgO, $Y_2O_3$, $Mn_3O$, $V_2O_5$, $BaCO_3$, $SiO_2$, and $Al_2O_3$ were used as additives. The electrical properties of the composites were determined by various amounts of additives and optimum sintering temperature. As a result of the optimized composite, it was possible to obtain a density of $5.77g/cm^3$, a dielectric constant of 1994, and an insulation resistance of $2.91{\times}10^{12}{\Omega}$ at an additive content of 5wt% and a sintering temperature of $1250^{\circ}C$. After forming a $2.5{\mu}m$ green sheet using the doctor blade method, a total of 77 layers were laminated and sintered at $1180^{\circ}C$. A decoupling capacitor with a size of $0.6mm(W){\times}0.3mm(L){\times}0.3mm(T)$ (width, length and thickness, respectively) and a capacitance of 100 nF was embedded using a PCB process for the 10G RF Transceiver modules. In the range of AC input voltage 400mmV @ 500kHz to 2200mV @ 900kHz, the embedded 10G RF Transceiver modules evaluated that it has better electrical performance than the non-embedded modules.