• Resources Recycling
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• v.13 no.6
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• pp.31-36
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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 were varried 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 x=0.2, respectively at stoichiometry, 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 370 kA/m. The squareness in 2nd quarter of BH curve with x=0.2 was smoothly improved to compared with x=0.3.

• Journal of Conservation Science
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• v.33 no.6
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• pp.485-495
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• 2017

The purpose of this study is to evaluate the functionality and lightfastness of the natural pigments according to the type of Seokganju used as Dancheong. The commercially available red iron-oxide-based natural pigments that are called Seokganju and Daija manufactured by traditional methods in Korea and Japan were selected. The analysis of the constituent minerals and constituents of 8 kinds of collected Seokganju showed that most of them contained hematite. There are two types of Seokganju according to the $Fe_2O_3$ contents. The type of Seokganju can be characterized not only using the main component but also from the burn-out processing. The chromaticity results for Seokganju with a high $Fe_2O_3$ concentration indicate dark red or grayish brown, while those for Seokganju with a low $Fe_2O_3$ concentration indicate yellowish red or yellowish brown. Samples were prepared by mixing with a glue solution and functional properties were evaluated based on the opacity and spreadability. Coated samples were used in the lightfastness test. The spreadability and opacity of the pigments were measured differently depending on the main component. Most Seokganju samples a showed slight color change until $9,000kJ/m^2$ but rapid color changes were detected after $18,000kJ/m^2$. In particular, burnt Seokganju showed superior lightfastness.

• Asian Pacific Journal of Cancer Prevention
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• v.15 no.1
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• pp.49-54
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• 2014

Background: Hydrogels are a class of polymers that can absorb water or biological fluids and swell to several times their dry volume, dependent on changes in the external environment. In recent years, hydrogels and hydrogel nanocomposites have found a variety of biomedical applications, including drug delivery and cancer treatment. The incorporation of nanoparticulates into a hydrogel matrix can result in unique material characteristics such as enhanced mechanical properties, swelling response, and capability of remote controlled actuation. Materials and Methods: In this work, synthesis of hydrogel nanocomposites containing magnetic nanoparticles are studied. At first, magnetic nanoparticles ($Fe_3O_4$) with an average size 10 nm were prepared. At second approach, thermo and pH-sensitive poly (N-isopropylacrylamide -co-methacrylic acid-co-vinyl pyrrolidone) (NIPAAm-MAA-VP) were prepared. Swelling behavior of co-polymer was studied in buffer solutions with different pH values (pH=5.8, pH=7.4) at $37^{\circ}C$. Magnetic iron oxide nanoparticles ($Fe_3O_4$) and doxorubicin were incorporated into copolymer and drug loading was studied. The release of drug, carried out at different pH and temperatures. Finally, chemical composition, magnetic properties and morphology of doxorubicin-loaded magnetic hydrogel nanocomposites were analyzed by FT- IR, vibrating sample magnetometry (VSM), scanning electron microscopy (SEM). Results: The results indicated that drug loading efficiency was increased by increasing the drug ratio to polymer. Doxorubicin was released more at $40^{\circ}C$ and in acidic pH compared to that $37^{\circ}C$ and basic pH. Conclusions: This study suggested that the poly (NIPAAm-MAA-VP) magnetic hydrogel nanocomposite could be an effective carrier for targeting drug delivery systems of anti-cancer drugs due to its temperature sensitive properties.

• Conservation Science in Museum
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• v.17
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• pp.69-84
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• 2016

Yuso is the term for decorative tassels of a braided string which hangs a scroll painting. This study, drawing on extant research concerning the yuso made for Joseon period portrait scrolls of kings and meritorious retainers, focuses on the yuso created to hang literati portraits. Concretely, It examines yuso of seven portraits in the collection of the National Museum of Korea in order to characterize their appearance and determine their material composition. The study found that most of the yuso are sixteen-strand strings braided into a rounded cross-section(dongdahoe). The seven yuso, of which six are red and one indigo-blue, reflect the popular style associated with Joseon period literati portraits. The yuso for the portrait of Yun Geup(duksu 3503) is made from gilded paper. Analysis showed Fe particles present in a red pigment underlying the gold layer, suggesting the presence of red ochre(seokganju), an iron oxide mineral. The yuso of the portrait of Shin Im(duksu 4846) is used a paper which contains gold as well as traces of Pb, Hg and Ag. The paper in the yuso for the portrait of Yi Seongwon(bongwan 10122) mainly consisted of Ag, indicating silver paper having been used in its fabrication. The inner paper in the yuso of the portrait of Yi Seogu(sinsu 1065) is a leather combined with Ag, Fe, and Br, according to chemical analysis. The FTIR of the leather sample reveals that the spectrum in the fingerprint region is nearly identical to that of sheepskin, indicating the yuso was made from gold-coated sheepskin.

• Journal of the Mineralogical Society of Korea
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• v.32 no.4
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• pp.273-285
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• 2019

This study is aimed to interpret the raw material characteristics and manufacturing technology through physical, mineral and geochemical analysis of the brown-glazed stonewares and roof tiles excavated from the Hong Nang Sida temple in Laos, which was built in the 12th century. The glaze of brown-glazed stoneware is a typical lime serial with CaO content of more than 15 % and they were vitrified. The body is the combination of quartz, mullite and cristobalite, but had not vitrified texture, and therefore, which is assumed to have been fired more than 950 ℃. Meanwhile, The roof tiles are unglazed and its outer color is reddish brown, whitish grey and bluish grey. The bluish gray tiles has sandwich structure, which seem to experience imperfect reducing environment. The tile samples with a number of amorphous iron oxide nodule had a very similar chemical composition. In conclusion, it is assumed that the clay source was made from raw material produced from the same bedrock. The firing temperature of roof tiles were divided into less than 900 ℃, 900~950 ℃ and greater than 950 ℃ according to detection of micas, hercynite and mullite.

• Journal of Magnetics
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• v.11 no.4
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• pp.195-207
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• 2006

The recently published and new results on design and fabrication of magnetophotonic crystals of different dimensionality are surveyed. Coupling of polarized light to 3D photonic crystals based on synthetic opals was studied in the case of low dielectric contrast. Transmissivity of opals was demonstrated to strongly depend on the propagation direction of light and its polarization. It was shown that in a vicinity of the frequency of a single Bragg resonance in a 3D photonic crystal the incident linearly polarized light excites inside the crystal the TE- and TM-eigen modes which passing through the crystal is influenced by Brags diffraction of electromagnetic field from different (hkl) sets of crystallographic planes. We also measured the faraday effect of opals immersed in a magneto-optically active liquid. It was shown that the behavior of the faraday rotation spectrum of the system of the opal sample and magneto-optically active liquid directly interrelates with transmittance anisotropy of the opal sample. The photonic band structure, transmittance and Faraday rotation of the light in three-dimensional magnetophotonic crystals of simple cubic and face centered cubic lattices formed from magneto-optically active spheres where studied by the layer Korringa-Kohn-Rostoker method. We found that a photonic band structure is most significantly altered by the magneto-optical activity of spheres for the high-symmetry directions where the degeneracies between TE and TM polarized modes for the corresponding non-magnetic photonic crystals exist. The significant enhancement of the Faraday rotation appears for these directions in the proximity of the band edges, because of the slowing down of the light. New approaches for one-dimensional magnetophotonic crystals fabrication optimized for the magneto-optical Faraday effect enhancement are proposed and realized. One-dimensional magnetophotonic crystals utilizing the second and the third photonic band gaps optimized for the Faraday effect enhancement have been successfully fabricated. Additionally, magnetophotonic crystals consist of a stack of ferrimagnetic Bi-substituted yttrium-iron garnet layers alternated with dielectric silicon oxide layers of the same optical thickness. High refractive index difference provides the strong spatial localization of the electromagnetic field with the wavelength corresponding to the long-wavelength edge of the photonic band gap.

• Journal of the Korean Ceramic Society
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• v.40 no.8
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• pp.758-764
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• 2003

The cylindrical ${\gamma}$-alumina pellets were prepared by forming, hydration, drying and calcination after mixing amorphous alumina and pore generating agent with water. Concentration of Fe(NO$_3$)$_3$ㆍ9$H_2O$ that was catalyst precursor was fixed and made mixing solution that changed concentration of $CH_3$COOH in range of 2.5~20%, and here ${\gamma}$-alumina pellets were immerged and were hydrothermaly treated for 3 h at $200^{\circ}C$. And then we investigated creation and change of crystal, pore characteristics, $N_2$ adsorption and desorption isotherms, changes of acid site and mechanical strengths etc. According to the concentration of $CH_3$COOH, the crystals grew to acicular shape of 0.5~2${\mu}m$ length, and crystal structure showed the pseudo-boehmite structure. When hydrothermaly treated in 10% $CH_3$COOH solution, pore volume between 100~1000 $\AA$ was highest by 0.86 cc/g, and width of hysteresis curved line due to $N_2$ adsorption/desorption appeared as was smallest. When concentration of $CH_3$COOH was in range of 5~15%, new C-H functional groups were formed. Mechanical strength of pellets was highest by 1.35 MPa when $CH_3$COOH concentration was 2.5%.

• Journal of the Korean Magnetics Society
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• v.6 no.4
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• pp.204-210
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• 1996

M type hexa-ferrites were prepared by means of a solid state reaction using mill scale, $Fe_{2}O_{3}$, and the mixture of mill scale and $Fe_{2}O_{3}$. The mixture of powders were calcined at $1150^{\circ}C$ for 2 hrs. and sintered at $1250^{\circ}C$ for 2 hrs, with varing the mole ratio of $Fe_{2}O_{3}$/$BaCO_{3}$, by 5.2~6.0. And the magnetic properties and morphologies of Baferrites with impurities such as $SiO_{2},\;Al_{2}O_{3},\;MgO,\;CaO\;and\;Na_{2}O$ in the mill scale were investigated. The magnetic properties were worsened by the addition of $Na_{2}O because of non-reacted iron oxide and intermediate compound of $BaFe_{2}O_{4}$ but they were improved apparently by the addition of $Si_{2}$ and $Al_{2}O_{3}$ in the composition of $BaO.5.6Fe_{2}O_{3}$. Moreover, $M_{s}$ decreased but $_{B}H_{C}$ increased through the addition of $Al_{2}O_{3}$ in Ba-ferrite. ${(BH)}_{max}$ of sintered BM($BaCO_{3}$, mill scale mixture) and BFM($BaCO_{3}$, $Fe_{2}O_{3}$, and null scale mixture) were 0.86 and 1.04 MGOe, respectively, and the magnetic properties were changed around $440^{\circ}C$.

• 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.