• Economic and Environmental Geology
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• v.29 no.5
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• pp.545-559
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• 1996

Rare metal (Nb-Zr-REE) ore deposits are located in the Chungju area. Geotectonically, the rare metal ore deposits are situated in the transitional zone between Kyeonggi massif and Okcheon belt. The rare metal deposits are distributed in Kyemyeongsan Formation which consist of schist and alkaline igneous rocks. Alkali granite has suffered extensive post-magmatic metasomatism and hydrothermal processes. The ore contains mainly Ce-La, Ta-Nb, Y, Y-Nd, Nd-Th group minerals. More than 15 RE and REE minerals are found in the ore deposits. Allanite, one of the Ce-La rich REE minerals belonging to the epidote group, is the most common mineral in the studied area. The allanite- bearing rocks may be devided into seven types by features of occurrence and mineral associations; zircon type (ZT), allanite-vein type (AT), feldspar type (KT), fluorite type (FT), quartz-mica type (QT), iron-oxide type (MT), and amphibole type (HT). The allanite veins (AT) and zircon rich rocks (ZT) contain the highest total REE contents. Differences in REE abundance can be interpreted in terms of varying portions of magmatic hydrothermal fluid. Petrographical and chemical data are presented for allanites which were collected from different types. The allanites show wide variations in optical properties, due in part to differences in their chemical composition (depending on the types) and to the degree of crystallinity of the individual specimens. Allanite metamicts in biotite are generally surrounded by well developed pleochroic haloes. Usually, allanite is accompanied by zircon and other REE-bearing minerals. CaO and total REE contents $({\sum}RE_2O_3)$ range from 9.29 to 18.79% and 11.66 to 26.31%, respectively. Also, SiO, (28.87~32.61%), $Al_2O_3$ (8.30~16.88%), and $Fc_2O_3$ (16.74~24.38%) contents show varying contents from type to type. The ${\sum}RE_2O_3$ of allanite has positive relationships with $Fe_2O_3$ and negative relaton with CaO, $SiO_2$, and $Al_2O_3$ Backscattered electron microscope images (BEl) of allanite shows that the its mineral composition and texture is very complex. The allanite-bearing hosts show distinct light REE enrichment with strong negative Eu anomaly except for HI. The HT has an almost flat REE distribution pattern with a small negative Eu anomaly. The chemical variation of the allanites with occurrences and mineral association can be related to condition of temperature and oxidation states in precipitation environment.

• Journal of environmental and Sanitary engineering
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• v.7 no.2
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• pp.95-110
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• 1992

Much progress has been made in understanding the subcellular events of the human lung injuries after acute exposure to environmental air pollutants. Host of those events represent oxidative damages mediated by reactive oxygen species such as superoxide, hydrogen peroxide, and the hydroxy, free radical. Recently, nitric oxide (NO) was found to be endogenously produced by endothelial cells and cells of the reticulo-endothelial system as endothelialderived relaxation factor (EDRF) which is a vasoactive and neurotransmitter substance. Together with superoxide, NO can form another strong oxidant, peroxonitrite. The relative importance of exogenous sources of $N0/N0_2$ and endogenous production of NO by the EDRF producing enzymes in the oxidative stresses to the heman lung has to be elucidated. The exact events leading to chronic irreversible damage are still yet to be known. From chronic exposure to oxidant gases, progressive epithelial and interstitial damages develop. Type I epithelial cells become thicker and cover a smaller average alveolar surface area while thee II cells proliferate instead. Under acute damages, the extent of loss of the alveolar epithelial cell lining, especially type II cells appears to be a good predictor of the ensuing irreversible damage to alveolar compartment. Interstitial matrix undergo remodeling during chronic exposure with increased collagen fibers and interstitial fibroblasts. However, Inany of these changes can be reversed after cessation of exposure. Among chronic lung injuries, genetic damages and repair responses received particular attention in view of the known increased lung cancer risks from exposure to several air pollutants. Heavy metals from foundry emission, automobile traffics, and total suspended particulate, especially polycystic aromatic hydrocarbons have been positively linked with the development of lung cancer. Asbestos in another air pollutant with known risk of lung cancer and mesothelioma, but asbestos fibers are nonauthentic in most bioassays. Studies using the electron spin resonance spin trapping method show that the presence of iron in asbestos accelerates the production of the hydroxy, radical in vitro. Interactions of these reactive oxygen species with particular cellular components and disruption of cell defense mechanisms still await further studies to elucidate the carcinogenic potential of asbestos fibers of different size and chemical composition. The distribution of inhaled pollutants and the magnitude of their eventual effects on the respiratory tract are determined by pollutant-independent physical factors such as anatomy of the respiratory tract and level and pattern of breathing, as well as by pollutant-specific phyco-chemical factors such as the reactivity, solubility, and diffusivity of the foreign gas in mucus, blood and tissue. Many of these individual factors determining dose can be quantified in vitro. However, mathematical models based on these factors should be validated for its integrity by using data from intact human lungs.

• Journal of the Korean Ceramic Society
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• v.40 no.7
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• pp.683-689
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• 2003

The cylindrical ${\gamma}$-alumina pellets were prepared using amorphous alumina and pore generating agent. Its were immersed in aqueous solution of the mixture of Fe(NO$_3$)$_3$.9$H_2O$ and $CH_3$COOH, Fe(NO$_3$)$_3$.9$H_2O$ and $CH_3$COOH and HNO$_3$, and Fe(NO$_3$)$_3$.9$H_2O$ and HNO$_3$. The pellets thus were hydrothermally treated at 20$0^{\circ}C$ for 3 h in autoclave, and were investigated morphologies and changes of crystal pore characteristics, $N_2$ adsorption and desorption isotherms, active sites and mechanical strength etc. According to the preparation method, acicular platelet pseudo-boehmite crystals of 0.1~0.3 ${\mu}{\textrm}{m}$ size were transformed into acicular pseudo-boehmite cristals of 0.5~2 ${\mu}{\textrm}{m}$ size having the same crystal structure. When ${\gamma}$-alumina pellets were immersed in aqueous solution of the mixture of Fe(NO$_3$)$_3$.9$H_2O$ and $CH_3$COOH and then were hydrothermally treated, pore volume between 100 $\AA$ and 1000 $\AA$ was increased from 0.34 ㏄/g to 0.86 ㏄/g, and the gap of $N_2$ adsorption and desorption hysteresis loop was decreased due to increasement of pore size. New active site that could adsorb the C-H functional group was created on the catalist. Also, mechanical strength of catalyst was increased from 1.06 ㎫ to 1.36 ㎫.

• Journal of the Mineralogical Society of Korea
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• v.31 no.1
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• pp.23-32
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• 2018

Noerok ia a green pigment used in Joseon dynasty, and its main usage was for forming foundation layers of Dancheong, the ornamental paintings on the surface of traditional buildings in Korea, such as the Daeung-jeon(main hall) of Bulguk-sa temple. In this research, we investigated the mineralogical characteristic changes of Noerok, a traditional Korean pigment, depending on its firing temperature. The Noerok that we experimented on was mined from Noeseong Mountain, Pohang where it is locally reserved. The major composition mineral is Celadonite, and the main constituent elements are Fe, Si, K and Mg, that refers to the existence of Fe-rich mica. As a result of phased firing experiment from $105^{\circ}C$ to $1000^{\circ}C$, the color was changed from green to pale green, then to brown, and finally to red in order. In the thermal analysis, endothermic reaction induced by the dehydration of crystalline water was confirmed at around $616^{\circ}C$. In the mineralogical change, the crystal surface [($11{\bar{1}}$) and ($02{\bar{1}}$)] of the mineral collapsed at temperatures above $600^{\circ}C$, and iron oxide was formed at $1000^{\circ}C$ or higher. Therefore, it is estimated that the crystallization temperature of Noerok is below $600^{\circ}C$, and it is also considered that it has undergone the alteration phase up to stage I, based on the presence of only a celadonite.

• Proceedings of the Korean Institute of Resources Recycling Conference
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• 2004.12a
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• pp.27-34
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• 2004

This experiment was carried out to examine the effects of morphology on properties of La-Co substituted SrM ferrite. The magnetic properties of calcined and sintered materials varied with the substitutional amount of La and Co elements in Sr-ferrite. In the substituted SrM ferrite, the atomic fraction x of La is directly related to the mole ratio n of iron oxide and the atomic fraction y of Co by equation x=2ny. The HcJ values of the calcined powder were about 270 kA/m and 240 kA/m with x=0.3 and K=0.2, respectively at stoichiometriy, n=6.0. Crystallites of the sintered material were grown with a plate shape, and their size decreased with increasing mole ratios. Such a shape was caused by the initial state of crystallite formed after calcination. In case of x=0.3 and n=6.0, Br was 415 mT and HcJ was 355 kA/m, and in x=0.2 and n=6.0, Br was 410 mT and HcJ was 370kA/m. The squareness in 2nd quarter of BH curve with x=0.2 was smoothly improved compared with x=0.3

• Membrane Journal
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• v.22 no.6
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• pp.461-469
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• 2012

This study was carried out to find the optimum chemical cleaning (CIP) conditions for ceramic microfiltration membrane process of Y drinking water treatment plant. B train consists of coagulation as pretreatment process with membrane was chemically cleaned 9 times more than that of A train with ozonation and coagulation. The frequent CIP of B train was due to improper CIP method suggested by membrane manufacture as well as different membrane fouling between A and B train resulting from the different pretreatment processes. That is, recovery rate of CIP was overestimated because the rate was calculated based on normalized trans membrane pressure (TMP) rather than normalized permeability. And also, iron oxide fouling was ineffectively removed by citric acid. By using a mixture of 1% citric acid and 0.1 N sulfuric acid as reagent for acid CIP step, the recovery rate of CIP was the highest while CIP efficiency by 0.1 N sulfuric acid was the lowest. When sulfuric acid concentration increased from 0.1 N to 0.3 N in mixture, total recovery rate of CIP was not increased due to the decreased CIP efficiency in alkali CIP step by 0.3% NaOCl although its rate in acid CIP step was increased. It was proved through the experiment result of CIP sequence changes that an acid followed by alkali CIP was more effective than that of the reverse method.

• Conservation Science in Museum
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• v.23
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• pp.71-90
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• 2020

The scientific analysis of a 'F-51D Mustang Fighter'(Registered Cultural Heritage 666), one of the War Memorial of Korean collections, was carried out. The paint layer and canopy were discolored due to a constant outdoor exhibit. The results obtained through the scientific survey and analysis processes were intended to be used as basic data for the future dismantling and restoration of the fighter. The analysis results for the pigment components have confirmed red oxide of iron, Fe₂O₃ organic pigments, such as Cobalt Blue, phthalocyanine blue, etc., yellow PbCrO₄, white TiO₂, black Fe₃O₄, and gray Fe₃O₄ + TiO₂. It has been also confirmed that Alkyd resin was mainly used for painting. The fighter's canopy was Poly methyl methacrylate(PMMA), and Al was detected as the main component of the fighter body, wings, and tails.

• Journal of Conservation Science
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• v.36 no.5
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• pp.383-392
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• 2020

This study aimed to examine the characteristics of paint used for modern art works by conducting sectional observations, inorganic component analysis, and infrared spectroscopic analysis on the painted layers of 3 painted sculpture works exhibited in the Yongdam Dam Environmental Sculpture Park and Naejangsan Sculpture Park in the Jeollabuk-do area. The observations indicate that the cross section is composed of various layers of 2-3 folds, the thickness of the layers was uneven at approximately 23-150 ㎛, and putty was used for plate treatment prior to painting. Inorganic component analysis results show that putty containing calcium carbonate, iron oxide, diatomite, and titanium dioxide was used for the putty layer. It is also assumed that paint mixed with green (Cr₂O₃), blue(sodaliteblue), red(chromered), andwhite(TiO₂) colors were used for the painted layers. As a result of infrared spectroscopic analysis to confirm the types of paint, it is estimated that the paint was mixed with polyester resin and an extender.

• Journal of Conservation Science
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• v.36 no.5
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• pp.351-367
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• 2020

The pigments of three old and new celestial charts folding screens(『Celestial Chart(Folding Screen)』 and 『Old and New Celestial Charts, Eight-Panel Folding Screen』 of National Folk Museum of Korea and 『Koudou-Nanboku-Ryousouseizu』 of National Diet Library of Japan) were analyzed to estimate their dating. It was estimated that the 『Celestial Charts(Folding Screen)』 was painted using traditional pigments from the Joseon dynasty such as azurite, indigo lake, malachite, atacamite, vermilion, iron oxide, cochineal, gamboge, orpiment, lead white, talc and soot. The green and blue colors of the 『Old and New Celestial Charts, Eight-Panel Folding Screen』 and 『Koudou-Nanboku-Ryousouseizu』 were painted using artificial inorganic pigments such as emerald green and ultramarine blue. These pigments were imported from Europe post the mid-19th century. In the 『Old and New Celestial Chart, Eight-Panel Folding Screen』, only artificial inorganic pigments were used for green and blue colors. However in the 『Koudou-Nanboku-Ryousouseizu』, emerald green and atacamite in green color, and ultramarine blue and indigo lake in blue color were used together. Based on both the results of pigment analysis and the study of star charts and inscriptions, the 『Celestial Charts(Folding Screen)』 was painted post mid-18th century. The 『Koudou-Nanboku-Ryousouseizu』 and 『Old and New Celestial Charts, Eight-Panel Folding Screen』 were painted after green and blue artificial pigments were imported in the mid-19th century. The 『Koudou-Nanboku-Ryousouseizu』 in which both traditional and western artificial pigments were used, can be dated earlier than the 『Old and New Celestial Chart, Eight-Panel Folding Screen』.

• Economic and Environmental Geology
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• v.29 no.4
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• pp.411-419
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• 1996

The Janggun magnetite deposits occur as the lens-shaped magnesian skarn, magnetite and base-metal sulfide orebodies developed in the Cambrian Janggun Limestone Formation. The K-Ar age of alteration sericite indicates that the mineralization took place during late Cretaceous age (107 to 70 Ma). The ore deposition is divided into two stages as a early skarn and late hydrothermal stage. Mineralogy of skara stage (107 Ma) consists of iron oxide, base-metal sulfides, Mg-Fe carbonates and some Mg- and Ca-skarn minerals, and those of the hydrothermal stage (70 Ma) is deposited base-metal sulfides, some Sb- and Sn-sulfosalts, and native bismuth. Based on mineral assemblages, chemical compositions and thermodynamic considerations, the formation temperature, $-logfs_2$, $-logfo_2$ and pH of ore fluids progressively decreased and/or increased with time from skarn stage (433 to $345^{\circ}C$, 8.8 to 9.9 atm, 29.4 to 31.6 atm, and 6.1 to 7.2) to hydrothermal stage (245 to $315^{\circ}C$, 11.2 to 12.3 atm, 33.6 to 35.4 atm, and 7.3 to 7.8). The ${\delta}^{34}S$ values of sulfides have a wide range between 3.2 to 11.6‰. The calculated ${\delta}^{34}S_{H_2S}$ values of ore fluids are relatively homo-geneous as 2.9 to 5.4‰ (skam stage) and 8.7 to 13.5‰ (hydrothermal stage), which are a deep-seated igneous source of sulfur indicates progressive increasing due to the mixing of oxidized sedimentary sulfur with increasing paragenetic time. The ${\delta}^{13}C$ values of carbonates in ores range from -4.6 to -2.5‰. Oxygen and hydrogen isotope data revealed that the ${\delta}^{38}O_{H_2O}$ and ${\delta}D$ values of ore fluids decreased gradually with time from 14.7 to 1.8‰ and -85 to -73‰ (skarn stage), and from 11.1 to -0.2‰ and -87 to -80‰ (hydrothermal stage), respectively. This indicates that magmatic water was dominant during the early skarn mineralization but was progressively replaced by meteoric water during the later hydrothermal replacement.