• Korean Chemical Engineering Research
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• v.49 no.5
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• pp.676-680
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• 2011

Investigated was the effect of the crucial polymerization conditions such as methyl acrylate(MA) mole fraction in feed, polymerization temperature and time on Atom Radical Transfer Polymerization(ATRP) behavior of styrene and methyl acrylate(MA). As MA mole fraction in feed increased, molecular weight(MW) of the resulting copolymer increased. At polymerization time of 3 hrs the composition of MA in the resulting copolymer was shown to have a linear relationship with the mole fraction of MA in feed. MW was increased and the composition of MA in copolymer was decreased as the polymerization time increased, showing the characteristics of ATRP. MW was also increased as polymerization temperature increased, and the composition of MA in copolymer was shown to be increased drastically at polymerization temperature of $110^{\circ}C$.

• 한국석유지질학회:학술대회논문집
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• autumn
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• pp.50-67
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• 1999

Biostratigraphic and paleoenvironmental analyses are carried out on cutting samples from the Dolgorae wells drilled in the Ulleung basin. The clayey, silty, and sandy sediments of the wells yield various microfossil assemblages of relatively good preservation, among which five fossil groups are reported; a total of 97 foraminiferal species of 66 genera, 19 nannofossil species of 12 genera, 86 ostracod species of 41 genera, 107 diatom species of 44 genera, and 124 dinoflagellate cysts species of 45 genera. Based on microfossils the geologic ages of the Dolgorae wells are dated to be from late Early Miocene to Early Pleistocene. Several biohorizons are defined in Neogene successions by the LOD (Last Ocurrence Datum) and FOD (First Ocurrence Datum) of marker species including G. truncatulinoides (LOD: 1.9 Ma) of foraminifera; C. macintyeri (LOD: 1.64-1.60), G. oceanica (FOD: 1.65 Ma), G. caribbeanica (1.72 Ma), D. brouweri (LOD: 2 Ma), R. pseudoumbilica (LOD: 3.66 Ma), P. lacunosa (FOD: 4.2 Ma) of nannofossils; S. ellipsoideus (LOD: 4 Ma), S. palcacantha (LOD: 10.2), C. giusepei (LOD: 14 Ma) of dinocysts; D. seminae v. fossilis (FOD: 3.7 Ma), T. antiqua (LOD: 1.7 Ma), T. convexa (LOD: 2.4 Ma), N. kamtschatica (LOD: 2.58 Ma), T. oestrupii(FOD: 5.1 Ma) of diatoms. Abundance patterns of microfossils throughout the wells reflect changes in paleoenvironmental and sedimentological settings of the basin in relation to sea-level variations. According to these data the large-cycle and small-cycle changes of transgression and regression phases are observed in terrestrial to marine sediments. This high-resolution sequence biostratigraphy established by various fossil groups enabled more reliable correlation between strata and refined interpretation on deposition systems of the basin. It also proved to provide fundamental and precise informations regarding stratigraphic correlation, tectonic events, basin, and depositional history for hydrocarbon explorations, especially in collaboration with seismic-stratigrahic analyses.

• Korean Journal of Materials Research
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• v.11 no.5
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• pp.345-353
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• 2001

The present study was carried out to investigate the effect of zirconium addition to $Al_3$Nb intermetallic on the crystal structural modification and microstructural characterization of $Al_3$Nb intermetallic. Elemental Al, Nb, Zr powders and arc melted $Al_3$Nb and $Al_3$Zr intermetallic mixed powders were used as starting materials. MA was carried out in an attritor rotated with 300 rpm for 20 hours. The behavior of MA between two starting materials was some-what different in which the value of internal strain of the elemental powders was higher than that of the intermetallic powder. The intermetallic powder was much more disintegrated during the MA processing. In the case of the elemental powders, AlNb$_2$ phase were transformed to Al(Nb.Zr)$_2$ as a result of ternary addition of Zr element. With the successive heat treatment at 873K for 2 hours, the Al(Nb.Zr)$_2$ phase was transformed to more stable $Al_3$(Nb.Zr) phase. This transformation was clearly confirmed by the identification of X-ray peak position shift. On the other hand, in the carte of the intermetallic powder, there was no evidence of phase transformation to other ternary intermetallic compounds or amorphous phases, even in the case of additional heat treatment. However, nano-sized intermetallic with $Al_3$Nb and $Al_3$Zr were just well distributed instead of phase transformation.

• The Journal of the Petrological Society of Korea
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• v.14 no.2 s.40
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• pp.93-107
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• 2005

We determined $^{40}Ar/^{39}Ar$ ages of the Tertiary dike swarms and volcanic rocks distributed in the SE Korea where the most prevalent crustal-deformation and volcanism occurred during the period. In previous study, it was disclosed that the mafic dike swarms on both sides (east and west) of the Yeonil Tectonic Line (YTL) were originated from a same magma although they are consistently aligned with different intrusion directions of NS and NE, respectively. Ages of the mafic dike swarms of this study are $47.3\pm0.8Ma$ and $48.0\pm1.3Ma$, respectively and confirm such conclusion. These facts clarify that the YTL acted as a westernmost limit of the crustal deformation, especially clockwise crust-rotation, during the Miocene. Frequent occurrence of basic dikes indicate strongly that the southeastern part of the Korean Peninsula was under E-W extensional stress field at about 48 Ma, intimately related to the India-Asia collision and subsequent sudden change of the Pacific Plate motion. The ages of the uncommonly appearing intermediate and felsic dikes were determined as $55.9\pm1.5Ma$ and $53.0\pm1.0Ma$, respectively. Ages of the andesitic lava of the Hyodongri Volcanics, the dacitic lava of the Yongdongri Tuff, and dacitic rocks intruding and covering the Churyeong Breccia were determined as $24.0\pm0.5Ma,\;21.6\pm0.4Ma$, $21.8\pm0.1Ma,\;and\;22.0\pm0.5Ma$ respectively. The ages from the volcanics agrees well with the stratigraphy established by the latest field survey, which confirms that the $andesitic\~dacitic$ volcanism was followed by the basaltic volcanism during the Early Miocene.

• Journal of the Korean earth science society
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• v.36 no.1
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• pp.27-35
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• 2015

This study aims to establish the age of the Cretaceous Togeum Formation in Gurye that reported the discovery of dinosaur eggshells and bones. This study also investigates to determine the period of the dinosaurs' dominance in the region. K-Ar ages are measured on the whole volcanic rocks in the lower - and upper parts of the formation. The six samples dated are volcanic pebbles deposited in the Geumjeongri Conglomerate that is distributed underneath the Togeum Formation, and the ages dated as Aptian ($118.3{\pm}2.3Ma$) or Albian ($103.6{\pm}2.0$, $102.5{\pm}2.0$, $99.9{\pm}1.9Ma$), which all correspond to the Early Cretaceous. In addition, the ages of andesites and porphyritic andesites overlying the Togeum Formation are dated in a similar way. The result is that the ages are apparently corresponding to the Campanian ($83.9{\pm}1.6$, $74.2{\pm}1.5$Ma) of the Late Cretaceous. Field evidence and the age results indicate that the formation of the Togeum and the activities of dinosaurs dated back between 84 and 100Ma. It suggests that the Togeum Formation be somewhat older than the Boseong Seonso Formation (81Ma) which contains egg shells, the Haenam Uhangni Formation (79-81 Ma) that has dinosaur, pterosaur and webbed bird footprints, and also older than the theropod egg nests (77-83Ma) found in the Aphaedo area.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.25 no.6
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• pp.245-251
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• 2015

We have applied mechanical alloying (MA) to produce soft magnetic composite material using a mixture of elemental $Fe_2O_3$-Mg powders. An optimal milling and heat treatment conditions to obtain soft magnetic ${\alpha}$-Fe/MgO composite with fine microstructure were investigated by X-ray diffraction, differential scanning calorimetry (DSC) and vibrating sample magnetometer (VSM) measurement. It is found that ${\alpha}$-Fe/MgO composite powders in which MgO is dispersed in ${\alpha}$-Fe matrix are obtained by MA of $Fe_2O_3$ with Mg for 30 min. The saturation magnetization of ball-milled powders increases with increasing milling time and reaches to a maximum value of 69.5 emu/g after 5 h MA. The magnetic hardening due to the reduction of the ${\alpha}$-Fe grain size by MA was also observed. Densification of the MA powders was performed in a spark plasma sintering (SPS) machine at $800{\sim}1000^{\circ}C$ under 60 MPa. X-ray diffraction result shows that the average grain size of ${\alpha}$-Fe in ${\alpha}$-Fe/MgO nanocomposite sintered at $800^{\circ}C$ is in the range of 110 nm.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.23 no.6
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• pp.314-319
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• 2013

Fabrication of nanocomposite material for the $Fe_2O_3-Al$ system by mechanical alloying (MA) has been investigated at room temperature. It is found that ${\alpha}-Fe/Al_2O_3$ nanocomposite powders in which $Al_2O_3$ is dispersed in ${\alpha}-Fe$ matrix are obtained by mechanical alloying of $Fe_2O_3$ with Al for 5 hours. The change in magnetization and coercivity also reflects the details of the solid state reduction process of hematite by pure metal of Al during mechanical alloying. Densification of the MA powders was performed in a spark plasma sintering (SPS) machine using graphite dies at $1000^{\circ}C$ and $1100^{\circ}C$ under 60 MPa. Shrinkage change after SPS of MA'ed sample for 5 hrs was significant above $700^{\circ}C$ and gradually increased with increasing temperature up to $1100^{\circ}C$. X-ray diffraction result shows that the average grain size of ${\alpha}-Fe$ in ${\alpha}-Fe/Al_2O_3$ nanocomposite sintered at $1100^{\circ}C$ is in the range of 180 nm. It can be also seen that the coercivity (Hc) of SPS sample sintered at $1000^{\circ}C$ is still high value of 88 Oe, suggesting that the grain growth of magnetic ${\alpha}-Fe$ phase during SPS process tend to be suppressed.

• The Journal of Engineering Geology
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• v.19 no.4
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• pp.459-474
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• 2009

By the analysis of discontinuity at the outcrop and lineament on the satellite image, the joints have deeply relationship with the lineaments. The joint spaces at the drilling core are mostly 1~20 cm but at the rhyolite which is distributed near fault they have more closely. These volcanic rocks belong to the subalkaline series tuff, rhyolite, basalt in the study area from the diagram of $Nb/Y-Zr/TiO_2$. The composition diagram of Hf/3-Th-Nb/16 show destructive plate-margin basalt and their differentiates. The environment of formation of volcanics are normal continental arc. Most of LREE show high enriched pattern but HREE show depleted pattern. The K/Ar age of intermediate volcanics, tuff, rhyolite, crystal tuff are 55.3Ma, 77.25 Ma~91.22Ma, 63.16~64.39Ma, 54.49 Ma respectively.

• Journal of Animal Environmental Science
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• v.13 no.3
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• pp.153-160
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• 2007

Study for the effect of three different microbial feed additives(henceforth MA-A, MA-B, and MA-C) on feed coversion rate, and physical and chemical characteristics of swine finisher was conducted. MA-B had higher number of Lactobacillus spp. and yeast, compared to any other. The amylase activity of MA-B was also higher than any other. The daily feed intake rates of pigs fed control, MA-A, MA-B and MA-C were 3.15, 3.14, 3.31 and 3.42 kg, respectively. MA-C had the highest weight gain. However, there was no significant difference between treatments. The weights of feces daily excreted by pigs fed control, MA-A, MA-B, and MA-C were 2.14, 2.02, 2.18, and 2.23 kg/day, respectively. The volume of urine daily excreted by pigs fed control, MA-A, MA-B, and MA-C were 3.14, 3.26, 3.27, and $3.41\;{\ell}/day$, respectively. Water content, T-N, $P_{2}O_{5}$, and $K_{2}O$ in swine manure were not significantly different between treatments. The BOD were between 42,576 and $67,450\;mg/{\ell}$ for feces and were between 5,882.5 and $8,657.5\;mg/{\ell}$ for urine, respectively. The SS were between 138,000 and $180,000\;mg/{\ell}$ for feces and were between 875.0 and $1450.0mg/{\ell}$ for urine, respectively.

• Membrane Journal
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• v.17 no.2
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• pp.140-145
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• 2007

In this study, 3-(trihydroxysilyl)-1-propanesulfonic acid (THS-PSA) was added to poly(vinyl alcohol) (PVA) membranes crosslinked with poly(styrene sulfonic acid-co-maleic acid) (PSSA_MA) to improve the separation characteristics toward water vapors in the air. The prepared membranes varying both PSSA_MA and THS-PSA amounts were also synthesized at different cross linking temperatures. Then, in order to investigate the separation characteristics of the resulting membranes, the dynamic vapor sorption (DVS) and vapor permeation experiments were carried out. The increase of cross-linking temperature showed longer time to reach the equilibrium sorption state from the dynamic vapor sorption experiments. PVA/PSSA_MA (3%)/THA-PSA(7%) prepared at $120^{\circ}C$ gave the highest permeability of 480 barrer at $35^{\circ}C$.