• Proceedings of the Korean Magnestics Society Conference
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• 2002.12a
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• pp.232-233
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• 2002

Nanostructed high energy Nd-Fe-B based bulk magnet can be prepared by hot-working process (hot press and die-upset) from melt-spun amorphous or nanocrystalline powder.[1] Recently, we have investigated a modified method, current-applied pressure-assisted (CAPA) process, to produce nanocrystalline isotropic and anisotropic NdFeB magnets. The process consists of current-applied pressing the melt-spun powders to obtain isotropic precursor subsequent current-applied deforming the precursor to obtain textured magnet.[2-3] (omitted)

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.8 no.4
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• pp.655-659
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• 1998

The effect of quenching speed of melt-spinning on intrinsic coercivity ($_iH_c$$) of annealed ribbons and the crystallization behavior from amorphous $Nd_{14.73}Fe_{78.67}B_{6.60}$ alloy have been studied. We have found that the intrinsic coecivity for annealed melt-spun ribbon is reduced with increasing of quenching rate. $\alpha$-Fe and $Fe_3B$ were formed as intermediate phases prior to the formation of $Nd_2Fe_{14}B$ phase during crystallization. The $Fe_3B$ is disappeared with crystallization of $Nd_2Fe_{14}B$ phase. But the $\alpha$-Fe phase is retained in fully crystallized ribbon by annealing. The intrinsic coercivity loss of annealed ribbon with increasing of quenching speed is believed to be due to existence of soft magnetic phase $\alpha$-Fe in annealed ribbons.

• Journal of Magnetics
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• v.4 no.4
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• pp.131-135
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• 1999

The HDDR characteristics of the Nd-Fe-B-type isotropic and anisotropic HDDR alloys were investigated using three types of alloys: alloy A $(Nd_{12.6}Fe_{81.4}B_6), alloy B (Nd_{12.6}Fe_{81.3}B_6Zr_{0.1}), and alloy C (Nd_{12.6}Fe_{68.8}Co_{11.5}B_6Ga_{1.0}Zr_{0.1}$). The alloy A is featured with the isotropic HDDR character, while alloy B and C are featured with the anisotropic HDDR character. Hydrogenation and disproportionation characteristics of the alloys were examined using DTA under hydrogen gas. Recombination characteristics of the alloys were examined by observing the coercivity variation as a function of recombination time. The present study revealed that the alloy C exhibits slightly higher hydrogenation and disproportionation temperatures compared to the alloy A and B. Recombination of the anisotropic alloy B and C takes place more rapidly with respect to the isotropic alloy A. The intrinsic coercivities of the recombined materials rapidly increased with increasing the recombination time and then showed a peak, after which the coercivities decreased gradually. The degraded coercivity was, however, recovered significantly on prolonged recombination treatment. Compared with the isotropic HDDR alloy A the anisotropic HDDR alloy B and C are notable for their greater recovery of coercivity. The significant recovery of coercivity was accounted for the in terms of the development of well-defined smooth grain boundary between the recombined grains on prolonged recombination.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.30 no.6
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• pp.923-928
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• 1997

The occurrence of butyltin compounds in the seawater and sediment of Masan Bay was investigated. The concentrations were in the range of $ND-0.059{\mu}g/\ell$ for tributyltin (TBT), $ND-0.091{\mu}g/\ell$ for dibutyltin (DBT) and $ND-0.720{\mu}g/\ell$ for monobutyltin (MBT) in the seawater, and $ND-0.233{\mu}g\;TBT/g.dry$, $ND-0.197{\mu}g-DBT/g.dry$ and $ND-0.684{\mu}g-MBT/g.dry$ in the sediment. Among the butyltin compounds, the major component in the seawater was MBT, while the predominant species in the sediment changed with time. The tributyltin concentrations in the sediment are approximately three orders of magnitude greater than the associated water column levels. Sediment/water partition coefficients (K) of TBT were between $0.6\times10^3\;and\;5.0\times10^3$.

• Korean Journal of Optics and Photonics
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• v.17 no.5
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• pp.455-460
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• 2006

The output characteristics of a ceramic Nd:YAC laser pumped by a fiber-coupled laser diode was investigated. An efficiency and a slope efficiency of 33.8 % and 39.3 % respectively were obtained, under an output coupler reflectance of 90.4 %. The laser power has decreased suddenly due to the thermal tensing effect more than 6 W pumping powers.

• Journal of Sericultural and Entomological Science
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• v.45 no.1
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• pp.10-17
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• 2003

This study was carried out to analyze physicochemical characteristics of sericin cocoon from silkworm, Bombyx mori. The degumming loss increased with increasing treatment time up to 2 hr, and temperature up to 130$^{\circ}C$. At 130$^{\circ}C$, degumming loss of Nd-s jam and Nd$\^$H/ jam were 100% while that of Baegok jam was 24%. Nd-s jam and Baegok jam ha high glycine content of 29.1∼46.3 mol% where as Nd$\^$H/ jam had high serine content of 32.6 mol%. Thermal denaturation temperatures were found at 218$^{\circ}C$ for Nd-s jam, 216$^{\circ}C$ for Nd$\^$H/ jam, and 218$^{\circ}C$ for Baegok jam. Before degumming, crystallinities obtained by FT-IR analysis were 44.3, 43.7, and 59.9% for Nd-s jam, Nd$\^$H/ jam, and Baegok jam respectively. After degumming, crystallinity increased to 61.8% for Baegok jam. Before degumming, crystallinitics obtained from XRD were 35.9, 33.5, and 47.2%, for Nd-s jam, Nd$\^$H/ jam, and Baegok jam. After degumming, crystallinity increased to 49.8% for Baegok jam. The molecular weight of Nd$\^$H/ jam were 9,417 in 1 hr, 3,744 in 2 hr, 4,944 in hr, and 3,910 in 6 hr.

• The Journal of the Petrological Society of Korea
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• v.13 no.3
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• pp.142-151
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• 2004

The metamorphic rocks of Yongin-Anseong area in Gyeonggi massif are composed of high-grade gneisses and schists which are considered as Precambrian basement, and Jurassic granite which intruded the metamorphic rocks. In this paper, we discuss the geochemical characteristics of metamorphic rocks and granites in this area based on REE and Nd isotope geochemistry. And we also discuss the petrogenetic relationship between metamorphic rocks and granites in this area. Most of Nd model ages (T$\_$DM/$\^$Nd/) from the metamorphic rocks range ca. 2.6Ga～2.9Ga which are correspond to the main crustal formation stage in Gyeonggi massif by Lee et. al. (2003). And Nd model ages show that the source material of quartzofeldspathic gneiss is slightly older than that of biotite banded gneiss. In chondrite-normalized rare earth element pattern, the range of (La/Yb)$\_$N/ value from biotite banded gneiss is 37～136, which shows sharp gradient and suggests that biotite banded gneiss was originated from a strongly fractionated source material. However, that of amphibolite is 4.65～6.64, which shows nearly flattened pattern. Particularly, the chondrite normalized REE patterns from the high-grade metamorphic rocks show the REE geochemisoy of original source material before metamorphism. In addition, the values of (La/Yb)$\_$N/ and Nd model ages of granite are 32～40 and 1.69Ga～2.08Ga, respectively, which suggest that the source material of granite is different from that of Precambrian basement such as biotite banded gneiss and quartzofeldspthic gneiss in the area.

• Resources Recycling
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• v.26 no.4
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• pp.79-87
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• 2017

Extraction and separation behaviors of La, Ce, Pr, Nd and Sm from light rare earth multi - component mixed solutions by Cyanex 572 were studied. As extractant concentration increased, the $pH_{50}$ values of all the five components decreased. When extractant concentration was larger than 0.6 M, the separation factor of La and Ce, Nd and Sm was higher than 10, while the separation factor between Ce and Pr, Pr and Nd was as low as 0.5~2.2. Addition of TBP to the 0.6 M Cyanex 572 had little synergistic effect on the phase separation rate and separation factor. From the analysis of experiment results, group separation of [La]/[Pr, Nd, Sm] and [Pr, Nd]/[Sm] could be possible, but in case of the group separation between [La, Ce] and [Pr, Nd] was not available because of the low separation factor between Ce and Pr.

• 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 POULTRY JOURNAL
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• v.38 no.2 s.436
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• pp.84-87
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• 2006

최근 문제가 되고 있는 ND가 현재의 양상으로 발생하기 시작한 것은 벌써 8년여가 된다. 필자가 양계전문병원을 시작할 무렵이 ND가 서서히 전국적으로 확산되던 시기이니, 대략 그 정도가 지난 것으로 보인다. 물론 지역별로 분석을 해보면 서해안쪽과 호남지역은 부분적으로 5~6년 정도 ND로 인한 피해를 경험한 지역도 있다. ND가 본격적으로 발병하기 시작할 무렵에는 많은 사람들이 유행적인 발병, 다시 말하면 일정기간 폭발적으로 발병하다가 없어질 질병으로 예상하였지만, 예상은 여지없이 빗나가고 오랜기간을 농가에 지속적으로 피해를 입히는 질병으로 남아 있다. 본소에서 질병관리를 하는 농장들에 대해 2000년도부터 ND를 혈청학적으로 집중 모니터링하기 시작했다. 본소가 출입하는 모든 농장들의 전 계군에 대해 일정간격으로 질병발생 여부에 상관없이 혈청모니터링을 실시하다보니 농장별 ND발생의 특징과 매년 ND가 발생하는 동향에 약간의 변화들을 감지할수 있었다. 그 대표적인 발생 동향으로 첫째 산란을 시작하기 전 높은 면역을 부여해주지못한 계군에서 산란급상승 기간 중에 ND발생으로 인한 피해를 들 수 있으며, 둘째는 주로 동절기에만 발생하던 ND가 이제는 1년 내내 발생하는 양상으로 바뀌어 온 것 등 두 가지 동향에 대해 분석을 해보기로 한다. ND의 발생동향 분석이 ND예방에 어떻게 참고가 될 것인지는 그것을 정확히 인식하기 위한노력을 기울이는 농장들과 발생동향에 따른 대책을 적극 수행하는 농장들에 달려있다. ND발생시 피해의 정도를 결정하는 것은 여러가지이다. 계군의 면역상태와 고른 면역 정도, 영양상태, 환경조건, ND바이러스의 병원성 정도 등 여러 조건에 따라 ND에 의한 피해 정도가 결정된다. 이러한 조건 중 어느 하나도 중요하지 않은 것은 없으며 이것들은 ND로 인한 피해정도를 결정하는 중요한 요소들이다.