• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2008.11a
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• pp.157-157
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• 2008

As the minimum feature size of semiconductor devices scales down to nano-scale regime, ultra shallow junction is highly necessary to suppress short channel effect. At the same time, Ni-silicide has attracted a lot of attention because silicide can improve device performance by reducing the parasitic resistance of source/drain region. Recently, further improvement of device performance by reducing silicide to source/drain region or tuning the work function of silicide closer to the band edge has been studied extensively. Rare earth elements, such as Er and Yb, and Pd or Pt elements are interesting for n-type and p-type devices, respectively, because work function of those materials is closer to the conduction and valance band, respectively. In this paper, we increased the work function between Ni-silicide and source/drain by using Pd stacked structure (Pd/Ni/TiN) for high performance PMOSFET. We demonstrated that it is possible to control the barrier height of Ni-silicide by adjusting the thickness of Pd layer. Therefore, the Ni-silicide using the Pd stacked structure could be applied for high performance PMOSFET.

• Korean Journal of Materials Research
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• v.17 no.4
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• pp.203-206
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• 2007

Effects of doping rare earth elements on Ln site of $Ln_{0.7}Ca_{0.3}MnO_3$ (Ln = N d, Sm and La) were examined from structure, magnetic and electrical properties. Size of a-axis increased as following order of La < Nd < Sm, whereas c-axis was not much changed. Curie temperatures of 170 K for $Nd_{0.7}Ca_{0.3}MnO_3$, 110 K for $Sm_{0.7}Ca_{0.3}MnO_3$ and 250 K for $La_{0.7}Ca_{0.3}MnO_3$ were obtained. This result coincides with change of Mn-O bond length causing by a-axis lattice constant. The highest magnetroresistance ratios were 22% at 77 K for $Sm_{0.7}Ca_{0.3}MnO_3$, 32% at 110 K for $Nd_{0.7}Ca_{0.3}MnO_3$, and 33% at 180 K for $La_{0.7}Ca_{0.3}MnO_3$.

• Journal of Magnetics
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• v.8 no.1
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• pp.1-6
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• 2003

The new class of $Gd_5(Si_xGe_{1-x})_4$ compounds undergoes a simultaneous magnetic/structural phase transition giving a high level of strain that can be induced either by change in temperature or by application of a magnetic field. Profound changes of structural, magnetic, and electronic changes occur in the $Gd_5(Si_xGe_{1-x})_4$ system lead to extreme behavior of the material such as the giant magnetocaloric effect, colossal magnetostriction, and giant magnetoresistance. These unique material characters can be utilized for various applications including magnetic solid refrigerants, sensors, and actuators.

• The Journal of the Petrological Society of Korea
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• v.5 no.2
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• pp.135-141
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• 1996

La-Ce method is one of new geochronological methods developed recently. La and Ce are one of the rare earth elements, and, with Sm-Nd system. La-Ce system is very useful in understanding the evolution processes of crust and mantle. In this paper, I introduce the basic concept of the La-Ce method, and apply it in clarifying LREE pattern of source material of leuco-granitic gneisses from the Imweon area, Kangwon-do, and K-rich granite from the Anshan area in Liaoning Province, NE China. Sm-Nd data on the Anshan K-rich granites give an age of $3.16{\pm}0.06$ Ga($2{\sigma}$), with initial $^{143}Nd/^{144}Nd$=$0.50846{\pm}0.00005$ (${\epsilon}_{Nd}$=-1.5). On the basis of Ce and Nd isotopic ratio, leucogranitic gneiss and K-rich granite has been fractionated from the source material which had had similar to CHUR (chundritic uniform reservoir). And the initial ${\epsilon}_{Nd}$ value suggest that the crustal formation age of the Liaoning Province area, NE China was early Archean.

• Journal of the Korean Ceramic Society
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• v.44 no.5 s.300
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• pp.155-159
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• 2007

Blue light-emitting phosphors having the excitation spectrum range of the medium-long ultraviolet ($280nm{\sim}400nm$) have been prepared by solid state reaction method. As a starting material the natural alkaline feldspar powder produced from the domestic mine field in Buyeo, Chungnam-do. The photoluminescence characteristics and crystal structures have been analyzed for the phosphor samples. The powder mixture of the natural alkaline feldspar and the rare-earth oxide was calcined at $800{\sim}1000^{\circ}C\;for\;3{\sim}4h$ in air. The calcined samples we fully ground at room temperature and then heat-treated in the mild reducing gas atmosphere of $5%H_2-95%N_2$ mixture at $1100{\sim}1150^{\circ}C\;for\;3{\sim}4h$. The natural alkaline feldspar material consists of the monoclinic orthoclase ($KAlSi_3O_8$) and the triclinic albite ($NaAlSi_3O_8$) phases. At the $0.5wt%Eu_2O_3$ addition the PL spectrum showed the maximum intensity and with further increase of $Eu_2O_3$ the PL intensity decreased. The albite phase disappeared in the $Eu_2O_3$ doped phosphors. The effect of the co-doped activator on the PL characteristics have been also discussed.

• Proceedings of the Korean Vacuum Society Conference
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• 2013.08a
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• pp.147-147
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• 2013

Multiferroic material $BiFeO_3$ (BFO) is a typical multiferroic material with a room-temperature magnetoelectric coupling in view of high magnetic- and ferroelectric-ordering temperatures (Neel temperature $T_N$ ~ 647 K and Curie temperature TC ~1,103 K). Rare-earth ion substitution at the Bi sites is very interesting, which induces suppressed volatility of the Bi ion and improved ferroelectric properties. At the same time, the Fe-site substitution with magnetic ions is also attracting, since the enhanced ferromagnetism was reported. In this study, BFO, $Bi_{0.9}Dy_{0.1}FeO_3$ (BDFO), $BiFe_{0.97}Co_{0.03}O_3$ (BFCO) and $Bi_{0.9}Dy_{0.1}Fe_{0.97}Co_{0.03}O_3 $ (BDFCO) compounds were prepared by conventional solid-state reaction and wet-mixing method. High-purity $Bi_2O_3$, $Dy_2O_3$, $Fe_2O_3$ and $Co_3O_4$ powders with the stoichiometric proportions were mixed, and calcined at $500^{\circ}C$ for 24 h. The samples were immediately put into an oven, which was heated up to 800oC and sintered in air for 1 h. The crystalline structure of samples was investigated at room temperature by using a Rigaku Miniflex powder diffractometer. The field-dependent magnetization measurements were performed with a vibrating-sample magnetometer. The electric polarization was measured at room temperature by using a standard ferroelectric tester (RT66B, Radiant Technologies). Dy and Co co-doping at the Bi and the Fe sites induce the enhancement of both magnetic and ferroelectric properties of $BiFeO_3$.

• Resources Recycling
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• v.22 no.4
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• pp.55-61
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• 2013

In this study, eco efficiency analysis is performed to analyze Neodymium (Nd) containing permanent magnet recycling process. Life cycle assessment (LCA) and life cycle costing (LCC) are used to apply eco efficiency analysis. In the environmental aspects, global warming potential (GWP) of 1kg permanent magnet is 1.25E + 00 kg $CO_2$ eq. and abiotic resource depletion potential (ADP) is 1.10E - 02 Sb eq. This recycling process costs about 2130 KWR. Environmental efficiency of GWP is at 6.43 and ADP is at 5.32 when compared with vigin metal. Economic efficiency is at 6.74. This study confirms that Nd containing permanent magnet recycling process is sustainable system because of environmental and economical improvement.

• Korean Journal of Metals and Materials
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• v.49 no.12
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• pp.937-944
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• 2011

Studies have been carried out in order to reduce fuel-cladding chemical interaction (FCCI) behavior of metallic fuel in sodium-cooled fast reactors (SFR) using an electroplating technique. A $20{\mu}m$ thick Cr layer has been plated by the electrochemical method in the Sargent bath over the HT9 (12Cr-1Mo) clad material and diffusion couple tests of the U-10Zr metallic fuel as well as the rare earth alloy (70Ce-29La) have been conducted. The results show that the Cr plating can prevent FCCI behavior along the fuel-clad interface. However, cracks developed through the thickness during plating, which resulted in the migration of some fuel constituents. Variation of bath temperature, application of pulse current, and post heat treatment have been conducted to control such cracks. We found out that some conditions like the pulse current and the post heat treatment enhanced the layer property by reducing the internal cracks and improving the diffusion couple test.

• Journal of Conservation Science
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• v.30 no.2
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• pp.205-217
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• 2014

The stone artifacts in Bronze age from the Sinsongri sites in Seosan, Korea were studied on material characteristics and provenance presumptions. The use and rock names of the artifacts are a stone before processing, two semifinished stone arrowheads and a grinding stone plate by slates. In addition, there is semifinished stone arrowhead by andesitic rocks. The slate could be observed easily around the site, and the andesitic rock could be confirmed typical occurrences of the all kinds of rocks around the Kanwoldo and Hwangdori, Anmyun area above 10km from the site. As a result of analysis which is comparing between stone artifacts and same kinds of raw material rocks, the stone artifacts made by slates have similar lithology and geochemical characteristics however, the stone artifacts made by andesitic rocks are found a some different part of characteristics to the same kind of raw material rocks. Comparing of major, rare earth, compatible and incompatible elements about stones artifacts made by slates and by the same kinds of raw material rocks have same geochemical patterns. However stone artifacts made by andesites and the raw material rocks are confirmed some differences of geochemistry. Therefore the slate stone artifacts in Sinsongri site suggest that these are domestic-type which are made of the rocks around the site, and it was understood that the andesitic stone artifacts are foreign-type which need to get more geological survey and study about different volcanic artifacts of the site around the area.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.4 no.3
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• pp.215-225
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• 1999

To study the vertical variations of major elements, trace elements and rare earth elements(REEs) contents in deep-sea sediments, six cores from Korea Deep-sea Environmental Study area(KODES) were analyzed. Topmost sediment layers of KODES area are divided into two Units; brown-colored and peneliquid Unit I and pale brown-colored and relatively solidified Unit II. Contents of major elements, REEs, Cu, Sr and Rb in each Unit are almost same, while contents of Mn, Ni and Co in Unit I are two or three times higher than those in Unit II. R-mode factor analysis represents that surface sediments are composed of alumino-silicate phase (AI-Ti-K-Mg-Fe-Rb-Ce), apatite phase (Ca-P-Cu-Sr-Trivalent Rare Earth Elements) and Mn-oxide phase(Mn-Ni-Co). Factor scores in silicate and apatite phases in each Unit are nearly same, whereas those in Mn-oxide phase in Unit I is higher than those in Unit II. While NilCu ratio in Unit I is two times higher than that in Unit II. We interprete the geochemical fractionation of Ni and Cu as a result that Ni can be remobilized in oxygen-depleted micro-environment in Units I and II and then easily reprecipitated in Unit I, while most of Cu supplied together with organic material is decomposed mostly in Unit I and sorbed into apatite.