• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.13 no.3
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• pp.206-213
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• 2000

The microstructure and electrical properties of Pr$_{6}$/O sub 11/-Based ZnO varistors with Nd$_2$O$_3$ was doped in the range of 0.0 to 2.0 mol% were investigated. Most of the added Nd$_2$O$_3$were segregated at the nodal points and grain boundaries and were found to form the Nd-rich phase. In addition the bulk intergranular layer at the grain boundaries and nodal points was consisted of Nd-rich phase and Pr-rich phase. the average grain size was decreased in the range of 7.8 to 5.6${\mu}{\textrm}{m}$ with increasing Nd$_{2}$/O sub 3/ additive content. The nonlinearity of ZnO varistors sintered at 130$0^{\circ}C$ was much more excellent than that at 135$0^{\circ}C$ ZnO varistors doped with 1.0mol% Nd$_{2}$/O sub 3/ exhibited the best nonlinearity. which is 65.2 in the nonlinear exponent and 4.5$\mu$A in the leakage current. Consequently. it is estimated that Pr$_{6}$/O sub 11/ -based ZnO varistors doped with 1.0 mol% Nd$_{2}$/O sub 3/ are to be sufficiently used as basic composition to fabricate good varistors in the future.ure.

• Transactions on Electrical and Electronic Materials
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• v.3 no.2
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• pp.24-27
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• 2002

The NdBaCuO superconductor samples were zone-melted in low oxygen partial pressure (1%O$_2$+99%Ar). The zone-melting temperature was decreased about 12$0^{\circ}C$ film 1,06$0^{\circ}C$, the zone-melting temperature in air. Thus the loss of liquid phase (BaCuO$_2$ and CuO) was reduced during: the zone-melting process. The content of non-superconducting phase Nd422 in zone-melted NdBaCuO samples was clearly decreased and, therefore, the substitution of Nd for Ba was occurred. The superconductivity of zone-melted Nd$_{1+x}$Ba$_{2-x}$Cu$_3$O$_{y}$ prepared under low oxygen partial pressure was distinctively improved.d.d.d.

• Korean Journal of Materials Research
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• v.6 no.2
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• pp.133-137
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• 1996

본연구에서는 n-type 세라믹 초전도체인 Nd2-xCexCuO4상의 산소함량에 따른 \ulcorner기적저항의 변화를 고찰하고자 하였다. 일반적인 소결과 어닐링과정을 결쳐 제조된 Nd1.85Ce0.15CuO4-x 시편을 여러 온도와 산소분압의 분위기하에서 어닐링시킴으로써 산소의 함유량이 다른 시편들을 준비하였고 각각의 시편의 산소함량은 TGA(Thermogravimetric Analysis0에 의해 측정하였다. Nd1.85Ce0.15CuO4-x시편의 전기적 저항 측정은 표준 4-탐침방법을 이용하여 액체헬륨을 주입시켜 상온으로부터 4K까지 측정하였다. Nd1.85Ce0.15CuO4-x시편의 산소함량, 3.96$\leq$4-x$\leq$4.0의 범위에서 전기적저항을 측정한 결과 초전도특성이 나타나기 시작한 임계산소함량은 4-x=3.990이었고 이때의 임계온도 Tc=12K이었다. 또한 임계온도, Tc는 산소함량 4-x=3.96에서 24K로 측정되었다. 특이할 만한 현상은 CuO/Cu2O 열역학적 상전이가 일어나는 조건이 Nd1.85Ce0.15CuO4-x 시편의 초전도가 일어나는 임계와 일치하였다. 즉, Cu2O가 안정한 영역에서는 초전도특성이 나타났고 CuO가 안정한 영역에서는 초전도특성이 나타나지 않았다.

• Journal of the Mineralogical Society of Korea
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• v.32 no.2
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• pp.127-143
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• 2019

The geology of the Chulmasan area consists of Precambrain Sogeunri formation, granitic gneiss, foliated biotite granite, foliated mica granite, basic dyke and acidic dyke. REE mineralization in the area occurs at granitic gneiss and foliated mica granite. Minerals with minor amounts of REE and Th from granitic gneiss and foliated mica granite are zircon ($Y_2O_3$ 0.00~1.18 wt.%, $Gd_2O_3$ 0.00~0.59 wt.%, $Er_2O_3$ 0.00~0.22 wt.%, $Yb_2O_3$ 0.00~0.34 wt.%, $Lu_2O_3$ 0.00~0.48 wt.%, $ThO_2$ 0.00~0.33 wt.%), thorianite ($Nd_2O_3$ 0.00~0.24 wt.%, $Lu_2O_3$ 0.00~0.26 wt.%), berthierine ($La_2O_3$ 0.04~0.26 wt.%, $Nd_2O_3$ 0.00~0.20 wt.%, $Tb_2O_3$ 0.04~0.12 wt.%, $Dy_2O_3$ 0.17~0.26 wt.%, $Er_2O_3$ 0.33~0.44 wt.%, $Lu_2O_3$ 0.00~0.19 wt.%, $ThO_2$ 0.61~0.93 wt.%), chlorite ($La_2O_3$ 0.44~0.68 wt.%, $Ce_2O_3$ 0.12~0.13 wt.%, $Nd_2O_3$ 0.31~0.44 wt.%, $Eu_2O_3$ 0.03~0.08 wt.%, $Dy_2O_3$ 0.09~0.21 wt.%, $Ho_2O_3$ 0.04~0.14 wt.%, $Er_2O_3$ 0.18~0.32 wt.%, $Lu_2O_3$ 0.07~0.21 wt.%, $ThO_2$ 0.00~0.97 wt.%), biotite ($Nd_2O_3$ 0.02~0.08 wt.%, $Gd_2O_3$ 0.07~0.08 wt.%, $Tb_2O_3$ 0.02~0.07 wt.%, $Dy_2O_3$ 0.35~0.43 wt.%, $Ho_2O_3$ 0.15~0.26 wt.%, $Er_2O_3$ 0.24~0.28 wt.%, $Yb_2O_3$ 0.06~0.18 wt.%, $ThO_2$ 0.00~0.12 wt.%), orthoclase ($Dy_2O_3$ 0.05~0.12 wt.%, $Ho_2O_3$ 0.05~0.06 wt.%, $Er_2O_3$ 0.28 wt.%, $Yb_2O_3$ 0.06~0.12 wt.%) and plagioclase ($Ho_2O_3$ 0.01~0.03 wt.%, $Er_2O_3$ 0.10~0.27 wt.%, $ThO_2$ 0.11~0.13 wt.%). REE minerals (bastnaesite and fergusonite) were sealed fractures in mainly fledspar, mica, zircon, apatite and ilmenite. Therefore, bastnaesite and fergusonite from the Chulmasan area were formed from redissolution/reconcentration of REE-and Th-bearing minerals from granitic gneiss and foliated mica granite at late stage by several igneous activies and metamorphism.

• Applied Chemistry for Engineering
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• v.24 no.3
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• pp.227-230
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• 2013

The phase change of $(U_{1-x}Nd_x)_3O_8$ powder produced by oxidation of Nd-doped $UO_2$ pellet at $500^{\circ}C$ was investigated by high temperature oxidation heat treatment at $900{\sim}1500^{\circ}C$ under an air atmosphere. The XRD analysis results showed that the formation of $(U_{1-y}Nd_y)O_{2+z}$ phase and $U_3O_8$ phase from metastable $(U,Nd)_3O_8$ phase initiated at a temperature of $1000^{\circ}C$. The relative integrated intensity of $(U_{1-y}Nd_y)O_{2+z}$ phase to $U_3O_8$ phase increased with increasing of the oxidation temperature from 1100 to $1500^{\circ}C$. And also, it was found from the SEM observation that the particle size of $(U_{1-y}Nd_y)O_{2+z}$ phase increased with increasing of the oxidation temperature. However, electrone probe X-ray microanalyzer (EPMA) analysis results showed that Nd contents in $(U_{1-y}Nd_y)O_{2+z}$ phase decreased with increasing of the oxidation temperature. This behavior on the ground of XRD, SEM, and EPMA analysis data could be interpreted in terms of the transportation of U ions from $U_3O_8$ phase into $(U_{1-y}Nd_y)O_{2+z}$ phase through the interface of two phases during high temperature oxidation.

• Korean Journal of Environmental Agriculture
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• v.15 no.3
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• pp.282-288
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• 1996

Because of the high water content of the household garbage, it is difficult to compost it. Therefore, this study was conducted to investigate the possibility of using coal fly ash as humidity conditioner for the household garbage composting. The summarized results are as follows : 1. The maximum temperatures were $35^{\circ}C$ in spring, $47^{\circ}C$ in summer, and $43^{\circ}C$ in winter during the composting periods. 2. The mass was reduced to 70.5% after 60 days. The average volume reduced down to 74.7% after 60 days. 3. The seasonal variation of pH values showed a similar tendency and reached 8.5 after 60 days. 4. The water content was reduced at an early stage of composting and not much changed thereafter. It had 49.7% in spring, 33.9% in summer, and 56.5% in winter after 60 days. Ash contents were not much changed during the composting periods. 5. The contents of inorganic compounds were in the range of $0.06{\sim}4.03%$ $P_2O_5$, $0.01{\sim}2.87%$ CaO, $0.18{\sim}1.43%$ MgO, and $0.39{\sim}2.03%$ $K_2O$. Heavy metal contents were in the range of $ND{\sim}14.08$ Hg ${\mu}g/kg$, $ND{\sim}0.80$ Cd mg/kg, $4.99{\sim}28.95$ Cu mg/kg, $ND{\sim}242.62$ Cr mg/kg, $ND{\sim}20.24$ Pb mg/kg, and $ND{\sim}59.87$ Zn mg/kg.

• Transactions on Electrical and Electronic Materials
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• v.3 no.3
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• pp.21-24
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• 2002

Two kinds of $Nd_{1+X}Ba_{2-X}Cu_3O_{7-{\delta}}$, the sintering samples and zone melting samples, were heat-treated under pure Ar at 950$^{circ}C$. The substitution of Nd ion for Ba ion in the $Nd_{1+X}Ba_{2-X}Cu_3O_{7-{\delta}}$ before and after the heat treatment was investigated by XRD. In order to confirm the effects of the heat treatment, the Tc and Jc of samples with/without the heat treatment under Ar were comparatively studied. $Nd_{1+X}Ba_{2-X}Cu_3O_{7-{\delta}}$ samples were oxygenated under pure oxygen at $300^{circ}C$. From the XRD pattern it was found that the sample with x<0.4 was transferred from tetragonal phase to orthorhombic phase after the oxygenation, while the sample with x>0.4 did not show the phase transition even after a long time oxygenation. Therefore, the low oxygen partial pressure (Ar+1 % O$_2$) was used for the ambient atmosphere of the zone-melting samples, which could reduce the melting temperature and depress the substitution of Nd for Ba. After the improvement in the zone-melting process, the Jc value was increased to 2 x $10^4$A/$cm^2$ (0 T, 78 K). The particle orientation and the structure of zone-melted NdBaCuO were studied by the XRD and SEM analysis.

• The Journal of Korean Obstetrics and Gynecology
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• v.25 no.1
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• pp.79-92
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• 2012

Purpose: Obesity affects dysfunction of Hypothalamus-Pituitary-Ovary(H-P-O) axis. Dysfunction of H-P-O axis could be related to Skin Resistance Variability (SRV). This study investigated the impacts of obesity which related to female age on SRV. Methods: We randomly selected 400 women who had taken CP-6000A test and InBody test on the same day at Oriental Hospital of Sangji University from Jan. 2008 to Jun. 2011. In this study, the Body Mass Index(BMI) range of normal group is 18.5~24.9, obesity group is over 25, the age range of childbearing age group is 24~34 years, post-menopause group is 50~65 years. 139 women that met the criteria of this study were assorted by their BMI and age. After detection of SRV, SPSS 19.0 has conjugated for data analysis and the independent samples t-test and paired samples t-test were used to verify the results. Results: At 1st and 2nd trial, the height of 3 area of childbearing age obesity group was significantly higher than that of childbearing age normal group. At 1st and 2nd trial, the height of 1, 2 area of childbearing age obesity group was higher than that of childbearing age normal group, but there were no significant difference. At 1st and 2nd trial, the height of 1, 2, 3 area of post-menopause obesity group was mostly higher than that of post-menopause normal group, but there were no significant difference. Conclusions: This study showed the SRV of obesity group was higher than that of normal group in most of 1, 2, 3 area. Further study will be needed.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.35 no.3
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• pp.292-296
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• 2022

(La_0.5Nd_0.2Sr_0.3)MnO₃ specimens were prepared by a solid-state reaction. In all specimens, X-ray diffraction patterns of an orthorhombic structure were shown. The fracture surfaces of (La_0.5Nd_0.2Sr_0.3)MnO₃ specimens showed a transgranular fracture pattern be possibly due to La ions (0.122 nm) as a perovskite A-site dopant substituting for Nd ions (0.115 nm) having a small ionic radius. The full-width at half maximum (FWHM) of the Mn 2p XPS spectra showed a value greater than that [8] of the single valence state, which is believed to be due to the overlapping of Mn²⁺, Mn³⁺, and Mn⁴⁺ ions. The dependence of Mn 2p spectra on the Mn³⁺/Mn⁴⁺ ratio according to sintering time was not observed. Electrical resistivity resulted in the minimum value of 100.7 Ω-cm for the specimen sintered for 9 hours. All specimens show a typical negative temperature coefficient of resistance (NTCR) characteristics. In the 9-hour sintered specimen, TCR, activation energy, and B25/65-value were -1.24%/℃, 0.19 eV, and 2,445 K, respectively.

• Bulletin of the Korean Chemical Society
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• v.24 no.1
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• pp.49-54
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• 2003

TiO₂nanoparticles were synthesized using the metallorganic chemical vapor deposition process. Particles with and without metal ion dopants were obtained. X-ray photoelectron and energy dispersive X-ray spectroscopic measurements confirmed the stoichiometry of the TiO₂nanoparticles. X-ray diffraction patterns showed a polycrystalline anatase structure of TiO₂. Transmission electron microscopy revealed that these particles are of nanoscale dimensions. Exact particle size and size distribution analyses were carried out by dynamic light scattering. The average particle size was determined to be 22 nm. The nanosize particles provided large surface area for photocatalysis and a large number of free surface-charge carriers, which are crucial for the enhancement of photocatalytic activity. To improve the photocatalytic activity, metal ions, including transition metal ions $(Pd^{2+},\;Pt^{4+},\;Fe^{3+})$ and lanthanide ion $(Nd^{3+})$ were added to pure TiO₂nanoparticles. The effects of dopants on photocatalytic kinetics were investigated by the degradation of 2-chlorophenol under an ultraviolet light source. The results showed that the TiO₂nanoparticles with the metal ion dopants have higher photocatalytic activity than undoped TiO₂. The $Nd^{3+}$ ion of these dopant metal ions showed the highest catalytic activity. The difference in the photocatalytic activity with different dopants is related to the different ionic radii of the dopants.