• Journal of the Korean Magnetics Society
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• v.1 no.2
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• pp.60-68
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• 1991

In compacting the melt-spun $Nd_{14}Fe_{76}Co_{4}B_{6}$ and $Nd_{10.5}Fe_{79}Co_{2}Zr_{15}B_{7}$ magnetic powders. the difference in composition induces a different behavior of closed packing rate as a function of aspect ratio of the powders. The $Nd_{10.5}Fe_{79}Co_{2}Zr_{1.5}B_{7}$ alloy having a low Co/Fe ratio (low density) shows the better green density to have an enhanced closed packing rate. An empirical power equation relating the green density with the compacting pressure was obtained such as ${\phi}(g/cm^{2})=5.2~5.6{\times}P^{0.045~0.065}(ton/cm^{2})$. The $Nd_{14}Fe_{76}Co_{4}B_{6}$ alloy having a high Nd/Fe ratio possesses much finer grain size(50~60 nm) than that of $Nd_{10.5}Fe_{79}Co_{2}Zr_{1.5}B_{7}$ alloy and shows the higher coercivity($iH_{c}=14~15kOe$). The higher Nd/Fe ratio in the melt-spun Nd-Fe-Co-B alloy, where the domain wall pinning mechanism was found to be predominant, assists the formation of Nd-rich grain boundary phase acting as a pinning site. The grain boundary ranges over $12~16\;{\AA}$ thick in the Nd-Fe-Co-B alloy while it ranges over $8~12\;{\AA}$ thick in the Nd-Fe-Co-Zr-B alloy.

• Journal of Sericultural and Entomological Science
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• v.45 no.1
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• pp.6-9
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• 2003

This experiment was done to know developmental characteristics of Sericin jam. Incubation periods were 10 day 2 hr, and 10 day 1 hr. 11 day 1 hr for Nd-s jam, N $d^{H}$ jam, and Baegok jam, respectively. Hatching rates were 83.9, 83.3 and 96.0% for Nd-s jam, N $d^{H}$ jam, and Baegok jam. Larval periods were, 20 days 1 hr for Nd-s jam, 20 days 5 hrs for N $d^{H}$ jam, and 22 days 12 hrs for Baegok jam. Death rate of larvae was highest in N $d^{H}$ iam, followed by Nd-s jam and Baegok jam. Pupation rate was highest in Baegok Jam followed by Nd-s jam and that of N $d^{H}$ jam was the lowest among the three. Cocoon weight was 1.39, 1.08, and 2.01 g for Nd-s jam, N $d^{H}$ jam, and Baegok jam, respectively. Shell weight were 13, 3, and 48 cg for Nd-s jam, N $d^{H}$ jam, and Baegok jam. Cocoon shell ratios were 9.0% for Nd-s jam, 2.8% for N $d^{H}$ jam and 23.9% for Baegok jam. Cocoon sizes were 30.6${\times}$15.8 mm for Nd-s jam, 24.7${\times}$14.9 mm for N $d^{H}$ jam and 35.8 ${\times}$ 20.5 mm(1${\times}$w) for Baegok jam.w) for Baegok jam.

• Journal of the Korean Magnetics Society
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• v.4 no.3
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• pp.244-248
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• 1994

Magnetic and Magneto-optical characteristics of NdTbFeCo alloy films and NdTbFeCo/TbFeCo double-layered films have been investigated. It was observed that the Kerr rotation(${\theta}_{k}$) in the short wavelength region increased and the coercivity decreased as the substitutional amount of Nd for Tb in NdTbFeCo film at the constant FeCo content. In spite of the increased ${\theta}_{k}$, a small coercivity of NdTbFeCo film made this medium unsuitable for magneto-optical recording medium at short wavelength. An effort was made to improve coercivity by exchange coupling with TbFeCo film of high coercivity. In the exchange-coupled $Nd_{16.9}Tb_{15.2}Fe_{50.4}Co_{17.5}(150\;{\AA})/Tb_{21.1}Fe_{65.0}Co_{13.9}(300\;{\AA})$ double-layered film, the magnetization reversal switching field and the Kerr rotation angle were increased to about 6.0 KOe and $0.32^{\circ}$ at 500 nm, respectively. This result indicates that exchange-coupled NdTbFeCo/TbFeCo film can be a promising candidate for agneta-optical rerding medium short wavelenhth.

• Journal of the Korean Ceramic Society
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• v.34 no.2
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• pp.139-144
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• 1997

Structurally, the rare earth cuprate superconductor of Nd2-xCexCuO4-$\delta$ has T' structure and has been known as having a quite complicated microstructural phenomena, so far. In order to be superconductivity, both small amount of cation substitution of Nd3+ by Ce4+ and oxygen reduction are required. In the present study the crystallographic study on the structural transition for the Nd2-xCexCuO4-$\delta$ crystal has been con-ducted by observing the CBED (Convergent Beam Electron Diffraction) pattern with STEM(Scanning Transmission Electron Microscope). Three different samples of Nd2CuO3,Nd1.85Ce0.15CuO4 and Nd1.85Ce0.15CuO3.965 were prepared by solid-state sintering and their CBED patterns were observed by STEM to study the structural transition accompanying the substitution of Ce and the reduction of oxygen. Experimental HOLZ lines of these samples were compared with those plotted by a computer-programmed simulation to de-termine the lattice parameter of Nd2-xCexCuO4-$\delta$ crystal.

• Journal of Life Science
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• v.14 no.4
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• pp.627-635
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• 2004

In order to distinguish the genetic polymorphism among the olive flounder (Paralichthys olivaceus) obtained from East sea of Jumunjin, aquaculture of Tongyoung and Geoje, and East sea of North Korea, the ND-4 and cytochrome b genes of olive flounder were divided into 5 regions. Each region was analyzed by degenerating gel electrophoresis scanning (DGES), and by subsequent DNA sequencing. The DGES disclosed characteristic DNA polymorphisms in ND-4-2 and ND-4-3 regions of olive flounder, which were also confirmed by the DNA sequencing. The olive flounders obtained from the different marine areas showed DNA mutations in ND-4-2 region (G390A, C402T, and A411G； GenBank： AB028664), and also showed frequent DNA mutations in ND-4-3 region (C515G, C537T, C538T, A567G, G714A, C736T, G756A, A759T, T817C, and T829G), white the cytochrome b gene showed no DNA mutation both in the DGES and DNA sequencing. These data suggest that the ND-4-2 and ND-4-3 regions are candidate loci to distinguish the origin of olive flounder, and that the DGES used in this study provided fast and reliable informations for the genetic polymorphism.

• Electrical & Electronic Materials
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• v.10 no.8
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• pp.819-829
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• 1997

The microwave dielectric materials of the BaO-Nd$_2$O$_3$-TiO$_2$and BaO-(Sm, Nd)$_2$O$_3$-TiO$_2$system were synthesized by conventional ceramic processing and sintered 1220 to 140$0^{\circ}C$ for 2 hours respectively. Their crystallization and dielectric properties were examined. In the BaO-Nd$_2$O$_3$-TiO$_2$ and BaO-(Sm, Nd)$_2$O$_3$-TiO$_2$system. Nd$_2$Ti$_2$O$_{7}$ and (Sm, Nd)$_2$Ti$_2$O$_{7}$ were observed as a second phase respectively. The maximum relative dielectric constant were 79,99 for the BaO-Nd$_2$O$_3$-TiO$_2$system and 105.07 for the BaO-(Sm,Nd)$_2$O$_3$-TiO$_2$system and their Q-value were over 2000 at 3GHz.GHz.

• Nuclear Engineering and Technology
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• v.33 no.4
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• pp.375-385
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• 2001

The total burnup in the spent U$_3$Si/Al fuel samples from Hanaro reactor was determined by destructive methods using $^{148}$ Nd, the sum of $^{143}$ Nd and $^{144}$ Nd, the sum of $^{145}$ Nd and $^{146}$ Nd, and the sum of total Nd isotopes($^{143}$ Nd, $^{144}$ Nd, $^{145}$ Nd, $^{146}$ Nd, $^{148}$ Nd and $^{150}$ Nd) monitors. The fractional($^{235}$ U) turnup in the spent fuel samples was also determined by U and Pu mass spectrometric method. The samples were dissolved in a mixture of 4 M HCI and 10 M HNO$_3$ without any catalyst. The separation of U, Pu and Nd from the spiked and unspiked sample solutions was achieved by two sequential anion exchange separation methods. The isotope compositions of these elements, after their separation from the fuel samples were measured by mass spectrometry. The contents of the elements in the spent fuel samples were determined by isotope dilution mass spectrometric method(IDMS) using $^{233}$ U, $^{242}$ Pu and $^{150}$ Nd as spikes. The effective fission yield was calculated from the weighted fission yields averaged over the irradiation period. The difference between total turnup values determined by various Nd monitors were in the range of 1.8%.

• Journal of the Korean Magnetics Society
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• v.2 no.1
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• pp.37-43
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• 1992

Minor phases in cast and hot-pressed R(R=Pr, Nd)-Fe-B magnet were investigated through thermomagnetic analysis. The relationship between minor phases and coercivities of R-Fe-B magnets was studied. ${\alpha}-Fe$ and $Nd_{2}Fe_{17}$ were precipitated in as-cast Pr-Fe-B and Nd-Fe-B alloys respectively. These phases were considered to deteriorate the magnetic properties of R-Fe-B magnets. During the heat treatment, ${\alpha}-Fe$ and $Nd_{2}Fe_{17}$ were annihilated and the magnetic properties of cast R-Fe-B magnet were improved. Hot-pressed Nd-Fe-B magnet showed better thermal stability than sintered magnet.

• Journal of the Korean Magnetics Society
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• v.8 no.4
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• pp.210-215
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• 1998

$Nd_{15}Fe_{77}B_8$ and $Nd_{16}Fe_{76}B_8$ powders were prepared by mechanical alloying in Ar atmosphere, and their phases and magnetic properties were investigated with as a function of the annealing temperature. It was found that the mechanical alloyed $Nd_{16}Fe_{76}B_8$ powder for 450 hours was amorphous phase with a part of $\alpha$-Fe crystallites. The obtained powders at 700 $^{\circ}C$ for 30 minute resulted in two phase of $Nd_2Fe_{14}B$ and $NdB_6$ by the solid-state reaction. The mechanical alloyed $Nd_{16}Fe_{76}B_8$ powder for 450 hour and annealed at 700 $^{\circ}C$ for 30 minute was showed $_iH_c\;of\;9.91\;kOe,\; B_{max}\;of\;12.93\;kG,\;Br\;of\;7.6\;kG\;and\;(BH)_{max}\;10.1\;MGOe$.

• 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.