• Korean Journal of Mineralogy and Petrology
• /
• v.36 no.4
• /
• pp.273-288
• /
• 2023

The Gubong Au-Ag deposit, which has been one of the largest deposits (Unsan, Daeyudong, Kwangyang) in Korea, consists of eight lens-shaped quartz veins (a mix of orogenic-type and intrusion-related types) that filled fractures along fault zones within Precambrian metasedimentary rock. Korea Mining Promotion Corporation found a quartz vein (referred to as the No. 6 vein with a grade of 27.9 g/t Au and a width of 0.9 m) at a depth of -728 ML by drilling (No. 90-12) conducted in 1989. Korea Mining Promotion Corporation conducted drilling (No. 04-1) in 2004 to investigate the redevelopment's possibility of the No. 6 vein. The author studied the occurrence and chemical composition of chlorite and white mica using wallrock, wallrock alteration and quartz vein samples collected from the No. 04-1 drilling core in 2004. The alteration of studied samples occurs chloritization, sericitization, silicification and pyritization. Chlorite and white mica from mineralized zone at a depth of -275 ML occur with quartz, K-feldspar, calcite, rutile and pyrite in wallrock alteration zone and quartz vein. Chlorite and white mica from ore vein (No. 6 vein) at a depth of -779 ML occur with quartz, calcite, apatite, zircon, rutile, ilmenite, pyrrhotite and pyrite in wallrock alteration zone and quartz vein. Chlorite from a depth of -779 ML has a higher content of Al and Mg elements and a lower content of Si and Fe elements than chlorite from a depth of -275 ML. Also, Chlorites from a depth of -275 ML and -779 ML have higher content of Si element than theoretical chlorite. Compositional variation in chlorite from a depth of -275 ML was mainly caused by phengitic or Tschermark substitution [Al^{3+,VI + Al3+,IV} <-> (Fe²⁺ or Mg²⁺)^VI + (Si⁴⁺)^IV], but compositional variation from a depth of -779 ML was mainly caused by octahedral Fe²⁺ <-> Mg²⁺ (Mn²⁺) substitution. The interlayer cation site occupancy (K+Na+Ca+Ba+Sr = 0.76~0.82 apfu, 0.72~0.91 apfu) of white mica from a depth of -275 ML and -779 ML have lower contents than theoretical dioctahedral micas, but octahedral site occupancy (Fe+Mg+Mn+Ti+Cr+V+Ni = 2.09~2.13 apfu, 2.06~2.14 apfu) have higher contents than theoretical dioctahedral micas. Compositional variation in white mica from a depth of -275 ML was caused by phengitic or Tschermark substitution [(Al³⁺)^VI + (Al³⁺)^IV <-> (Fe²⁺ or Mg²⁺)^VI + (Si⁴⁺)^IV], illitic substitution and direct (Fe³⁺)^VI <-> (Al³⁺)^VI substitution. But, compositional variation in white mica from a depth of -779 ML was caused by phengitic or Tschermark substitution [(Al³⁺)^VI + (Al³⁺)^IV <-> (Fe²⁺ or Mg²⁺)^VI + (Si⁴⁺)^IV] and direct (Fe³⁺)^VI <-> (Al³⁺)^VI substitution.

• Journal of Microbiology and Biotechnology
• /
• v.18 no.4
• /
• pp.663-669
• /
• 2008

The solvent-tolerant bacterium Enterobacter sp. VKGH12 is capable of utilizing n-butanol and contains an $NAD^+$-dependent n-butanol dehydrogenase (BDH). The BDH from n-butanol-grown Enterobacter sp. was purified from a cell-free extract (soluble fraction) to near homogeneity using a 3-step procedure. The BDH was purified 15.37-fold with a recovery of only 10.51, and the molecular mass estimated to be 38 kDa. The apparent Michaelis-Menten constant ($K_m$) for the BDH was found to be 4 mM with respect to n-butanol. The BDH also had a broad range of substrate specificity, including primary alcohols, secondary alcohols, and aromatic alcohols, and exhibited an optimal activity at pH 9.0 and $40^{\circ}C$. Among the metal ions studied, $Mg^{2+}$ and $Mn^{2+}$ had no effect, whereas $Cu^{2+},\;Zn^{2+}$, and $Fe^{2+}$ at 1 mM completely inhibited the BDH activity. The BDH activity was not inhibited by PMSF, suggesting that serine is not involved in the catalytic site. The known metal ion chelator EDTA had no effect on the BDH activity. Thus, in addition to its physiological significance, some features of the enzyme, such as its activity at an alkaline pH and broad range of substrate specificity, including primary and secondary alcohols, are attractive for application to the enzymatic conversion of alcohols.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.16 no.12
• /
• pp.8679-8683
• /
• 2015

Using a surface modification technique, ion beam assisted deposition (IBAD) of Ti thin film it becomes possible to prepare an active ceramic surface to braze $Al_2O_3$-STS304 with conventional Ag-Cu eutectic composition filler metal. Researches on bonding formations at interfaces of ceramic joints were mainly related on the development of filler metals to ceramic, the process parameters, and clarifications of reaction products. From the results, the reactive brazing is a very convenient technique compared to the conventional Mn-Mo method. However melting point of reactive filler is still higher than that of Ag-Cu eutectic and it forms the brittle inter metallic compound. Recently several new approaches are introduced to overcome the main shortcomings of the reactive metal brazing in ceramic-metal, metal vapor vacuum arc ion source was introduced to implant the reactive element directly into the ceramics surface, and sputter deposition with sputter etching for the deposition of active material.

• The Korean Journal of Food And Nutrition
• /
• v.22 no.2
• /
• pp.223-228
• /
• 2009

The principal objective of this study was to determine the available components in different varieties of Discorea spp. The Discorea spp. samples were divided into three groups by variety. The three groups were divided into Jangma(D. batatas Decaisne), Danma(D. japonica Decaisne), and Doonggunma(D. opposita Thumb), and then assessed with regard to the content of proximate compositions, minerals, sugars, crude saponin, and diosgenin. No substantial differences were noted to exist among samples in terms of carbohydrate and crude protein contents. The crude lipid contents were detected in the following order : Danma(D. japonica Decaisne, $0.71{\pm}0.15%$) > Jangma(D. batatas Decaisne, $0.65{\pm}10.12%$) > Doonggunma (D. opposita Thumb, $0.49{\pm}0.10%$). The Danma(D. japonica Decaisne) samples were determined to harbor the highest K($2.07{\pm}0.91%$), Ca($0.21{\pm}0.12%$), Fe($110.7{\pm}0.0$ mg/kg), Mn($20.6{\pm}3.4$ mg/kg) and Zn($31.2{\pm}3.9$ mg/kg) contents among all tested samples. The predominant sugar components in all samples were mannose($70.7{\pm}1.3{\sim}80.5{\pm}1.5%$), glucose($18.2{\pm}1.2{\sim}28.3{\pm}2.5%$) and sucrose($60.3{\pm}3.7{\sim}83.6{\pm}6.5%$). The crude saponin and diosgenin contents for Jangma(D. batatas Decaisne), Danma(D. japonica Decaisne) and Doonggunma(D. opposita Thumb) varieties were : $1.7{\pm}0.4%$, $3.9{\pm}0.8%$ and $3.2{\pm}0.7%$, and $13.59{\pm}1.74$ mg/g, $14.25{\pm}1.60$ mg/g and $18.00{\pm}1.92$ mg/g, respectively.

• The Korean Journal of Food And Nutrition
• /
• v.21 no.1
• /
• pp.35-42
• /
• 2008

To develop physiological functionality of Omija extracted with water was evaluated on antioxidative activity. Omija, high acid material with pH 3.6, contain $57.5{\pm}1.03%$ of moisture, and $18.8{\pm}0.12%$ of crude fat. This material have $12.6{\pm}0.04%$ of carbohydrate and $11.1{\pm}0.07%$ of crude protein as well, but ash and crude protein contents were found less than 10%. 10 mineral contents were also found, too; K and Ca showed the highest level, then Al, Mg, Na and Mn were followed. In composition amino acid contents, glutamic acid took the largest portion, $131.7{\pm}1.3$ mg/100 g, aspartic acid $51.5{\pm}0.6%$, and other composition amino acid under 50%. In case of free sugar contents, 7 types were found. Most of them were glucose and fructose. Total phenolic compounds showed the highest level, $2,862.6{\pm}31.7$ mg/100 g. $197.8{\pm}14.6$ mg/100 g of flavonoid and $225.6{\pm}18.2$ mg/100 g were included. In terms of electron donating ability, radical scavenging ability activated as the amount of Omija extract increased. In particular, Omija extract in 1,000 ${\mu}g/m{\ell}$ demonstrated almost similar electron donating ability, $72.4{\pm}0.21%$, to BHT. It was also found that antioxidant activities of electron donating ability, SOD-like ability, hydroxyl radical scavenging ability and nitrite scavenging ability were highly promoted as Omija extract concentration increased. The nitrite scavenging ability was significant when the extract belonged to strong acid region and doping concentrations increased.

• Korean Journal of Soil Science and Fertilizer
• /
• v.47 no.6
• /
• pp.391-397
• /
• 2014

Acid mine drainage occurrence is a serious environmental problem by mining industry; it usually contain high levels of metal ions, such as iron, copper, zinc, aluminum, and manganese, as well as metalloids of which arsenic is generally of greatest concern. It causes mine impacted soil pollution with mining and smelting activities, fossil fuel combustion, and waste disposal. In the present study, three bacterial strains capable of producing urease were isolated by selective enrichment of heavy metal contaminated soils from a minei-mpacted area. All isolated bacterial strains were identified Sporosarcina pasteurii with more than 98% of similarity, therefore they were named Sporosarcina sp. KM-01, KM-07, and KM-12. The heavy metals detected from the collected mine soils containing bacterial isolates as Mn ($170.50mg\;kg^{-1}$), As ($114.05mg\;kg^{-1}$), Zn ($92.07mg\;kg^{-1}$), Cu ($62.44mg\;kg^{-1}$), and Pb ($40.29mg\;kg^{-1}$). The KM-01, KM-07, and KM-12 strains were shown to be able to precipitate calcium carbonate using urea as a energy source that was amended with calcium chloride. SEM-EDS analyses showed that calcium carbonate was successfully produced and increased with time. To confirm the calcium carbonate precipitation ability, urease activity and precipitate weight were also measured and compared. These results demonstrate that all isolated bacterial strains could potentially be used in the bioremediation of acidic soil contaminated by heavy metals by mining activity.

• Journal of Environmental Science International
• /
• v.22 no.12
• /
• pp.1661-1669
• /
• 2013

This study conducted a laboratory simulation using artificial and natural rainfall in order to investigate the runoff characteristics of livestock resources through the analysis of the surface runoff water and infiltration water by rainfall intensity and fertilization level. Cattle manure and pig liquid fertilizer was used as livestock resource. As a result of this study, it was observed that the surface runoff occurred over 32 mm/hr rainfall intensity, and flow rate of the surface runoff water and the runoff ratio of contaminant parameters from livestock resource was increased, as rainfall intensity was stronger. With doubled fertilization level, T-N increased in compost and the amount of $COD_{Mn}$ runoff also considerably increased in liquefied fertilizer. In the case of natural rainfall, the runoff ratio of T-P clearly increased in compost and the T-N of final surface runoff ratio in compost and liquefied fertilizer was ranged from 0.13047 to 0.13623 with stronger rainfall intensity.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
• /
• v.21 no.12
• /
• pp.1077-1082
• /
• 2008

To fabricate a multi-layered piezoelectrics/electrodes structure, the piezoelectrics should be sintered at the temperature lower than $950^{\circ}C$ to use the silver electrode, which is cheaper than the electrodes containing noble metals such as Pd and Pt. Therefore, in this study, we modified the composition of $Pb(Zr,Ti)O_3$-based material as $(Pb_{0.98}Cd_{0.02})(Ni_{1/3}Nb_{2/3})_{0.25}Zr_{0.35}Ti_{0.4}O_3$ to lower the sintering temperature and to improve the piezoelectric properties. Small amount of $MnCO_3$, $SiO_2$, and $Pb_3O_4$ were also added to lower the sintering temperature of the ceramic. The prepared raw powders were mixed by using a ball mill for 24 hours. And then the mixed powders were calcinated for 2 hours at $800^{\circ}C$. The calcinated powders were again crushed with the ball mill for 72 hours. The final powders were pressed for making the shape of ${\emptyset}15\;mm$ disk. The disk-type samples were sintered at temperature range of $850{\sim}950^{\circ}C$. The crystal phases of the sintered specimens were perovskite structure without secondary phases. All of the measured electrical properties such as electromechanical coupling coefficients ($k_p$), mechanical quality factors ($Q_m$), and piezoelectric charge constants ($d_{33}$) were decreased with decreasing the sintering temperatures. The electrical properties measured at the sample sintered at $950^{\circ}C$ were 54% of $k_p$, 503 of $Q_m$, and 390 pC/N of $d_{33}$, respectively. These properties were considered to be fairly good for the application of multi-layered piezoelectric generators or actuators.

• Proceedings of the KIEE Conference
• /
• 1992.07b
• /
• pp.744-746
• /
• 1992

In this study, we investigated structural, electrical characteristics and studied the conditions which improved hydrostatic constants in hydrophones as we changed x = 0.1, 0.25, 0.35, 0.4 and y = 0.04, 0.08, 0.12, 0.16 in $(Pb_{1-x}Ca_x)[(Mg_{1/3}Nb_{2/3})_yTi_{1-0.01}Mn_{0.01}]O_3$ ceramics in which Ca was substituted with Pb and $Pb(Mg_{1/3}Nb_{2/3})O_3$ was added to decrease sintering temperature in $PbTiO_3$. When Ca was substituted 0.25[mol], the largest electro-mechanical anisotropy ($k_t/k_p$) was found ($k_t{\fallingdotseq}50,k_p{\fallingdotseq}4$), and the less $Pb(Mg_{1/3}Nb_{2/3})O_3$ and the stronger poling field, the larger this anisotropy was. When Ca=0.25[mol], $Pb(Mg_{1/3}Nb_{2/3})O_3=0.08[mol]$ were substituted, ($k_t/k_p$)(=12, 3) was large, permittivity was low and hydrostatic constants were high. Therefore, this composition is promising as wide band ultrasonic devices in water.

• Microbiology and Biotechnology Letters
• /
• v.22 no.2
• /
• pp.175-181
• /
• 1994

A bacterial strain producing highly viscous polysaccharide(A29 POL) was isolated from soil and identified sa Bacillus sp. A29. The cultural conditions of the Bacillus sp. A29 for the polysaccharide prouction were dextrin 12%, soytone 0.2%, SnCl$_{2}$ $\cdot $2H$_{2}$O 0.02%, Na$_{2}$HPO$_{4}$ $\CDOT $12H$_{2}$O 0.36%, L-alanine 0.01%, initial pH6.8, and 30$\circ $C at pH 3 FOR 4 days. Final viscosity of the culture broth was 65, 000 cp and then the amount of produced polysaccharide was 8.3 g/l. A29 POL was composed of glucose and xylose. A29 POL showed high viscosity at low concentration(0.1%) and in the presence of the salts such as NaCl or CaCl$_{2}$. A29 POL showed high viscosity acid condition and at alkali condition and high pseudoplasticity in the presence of a NaCl or CaCl$_{2}$. It was shown that the viscosity at high temperature(80$\circ $C) was decreased but it was recovered at low temperature (20$\circ $C. A29 POL was able to from film and gel in the presence of MgSO$_{4}$ $\CDOT $7H$_{2}$O, Na$_{2}$CO$_{3}$ \CDOT $H$_{2}$O, MnSO$_{4}$ $\CDOT $ 7H$_{2}$O. A29 POL had anionic charge.