• Journal of Korean Society of Environmental Engineers
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• v.37 no.8
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• pp.472-479
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• 2015

This study was investigated occurrence and distribution patterns of UV filters in Nakdong River basin (mainstream, tributaries and sewage treatment plant (STP) effluents). 5 (EHS, BP-3, 4-MBC, BZC and EHMC) out of 7 UV filters were detected in 5 out of 20 sampling sites (mainstream and tributaries), 7 UV filters were not detected in mainstream samples, and the EHS, BP-3, 4-MBC, BZC and EHMC concentration levels in tributary samples were ND~60.8 ng/L, ND~72.1 ng/L, ND~57.2 ng/L, ND~60.1 ng/L and ND~85.2 ng/L, respectively. 5 (EHS, BP-3, 4-MBC, BZC and EHMC) out of 7 UV filters were detected in effluents of 11 STPs around the Nakdong River basin. The EHS, BP-3, 4-MBC, BZC and EHMC concentration levels in 11 STP effluents were ND~89.3 ng/L, ND~90.8 ng/L, ND~88.1 ng/L, ND~118.5 ng/L and ND~104.4 ng/L, respectively. According to the sampling season, distribution patterns and detected concentrations of 5 UV filters were similar in June and September 2014, but change ranges of distribution patterns and detected concentrations of 5 UV filters were highly variable in April and November 2014.

• Journal of Magnetics
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• v.15 no.1
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• pp.32-35
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• 2010

The effects of Cu-addition and die-upset temperature on the texture in the die-upset Nd-lean $Nd_xFe_{93.5-(x+y)}-Cu_yGa_{0.5}B_6$ (x = 9-12, y = 0-2) alloys were investigated. The die-upset Cu-containing Nd-lean $Nd_{12}Fe_{81.5-y}-Cu_yGa_{0.5}B_6$ (y = 1, 2) alloys showed a considerable texture. Texture in the Nd-lean alloys developed through basal plane slip deformation. The Cu-addition reduced the melting point of grain boundary phase facilitating grain gliding during the die-upsetting, and providing a greater chance for the $Nd_2Fe_{14}B$ grains to meet the deformation conditions. Die-upsetting at higher temperature facilitated grain gliding and plastic deformation, thus enhancing texture.

• ETRI Journal
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• v.18 no.1
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• pp.15-27
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• 1996

The effects of $Nd_2O_3$ and $TiO_2$ addition on the microstructures and microwave dielectic properties of $BaO-Nd_2O_3-TiO_2$ system were investigated. $BaNd_2Ti_4O_{12}$ or $BaNd_2Ti_{5}O_{14}$ phases were observed for compositions based on BaO/$Nd_2O_3$ = 1 ratio. The compositions deviated from $BaO/Nd_2O_3=1$ ratio were composed of major phases of $BaNd_2Ti_4O_{12}$ or $BaNd_2Ti_5O_{14}$, and the compound of $Nd_2O_3$ and $TiO_2(Nd_2Ti_2O_7)$ or that of BaO and $TiO_2(BaTi_4O_9)$. The microstructure of ceramic with $BaO{\cdot}Nd_2O_3{\cdot}4TiO_2$ composition varied from spherical grains to needlelike grains with increasing sintering temperature. With increasing $Nd_2O_3$, the optimum sintering temperature with maximum density increased, and the dielectric constant(${\varepsilon}_r$) and quality factor(Q) decreased due to the formation of secondary phases. With increasing $TiO_2$, the optimum sintering temperature and the dielectric constant decreased with increased Q value. And the temperature coefficient of resonant frequency, ${\tau}_f$ shifted toward positive direction. The dielectric ceramics with $BaO/Nd_2O_3=1$ showed Q values of above 2000 and dielectric constants of above 80 at 3GHz.

• Journal of the korean academy of Pediatric Dentistry
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• v.11 no.1
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• pp.25-39
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• 1984

The author has sought to determine the time and the sequence of permanent teeth eruption in Korean children. The study group consisted of 15,671 healthy children (male 8,015 ; female 7,656) aged 5-13 years old who lived in Seoul or Cheongju. The results were as follows : 1. The eruption times of permanent teeth were 0.45 years earlier in females than in males. 2. The ages corresponding to $ER_{50}$ of permanent teeth were as follows : In Maxilla 1) central incisor was 7.37 yrs 2) lateral incisor was 8.50 yrs 3) canine was 10.83 yrs 4) 1st premolar was 10.30 yrs 5) 2nd premolar was 11.09 yrs 6) 1st molar was 6.49 yrs 7) 2nd molar was 12.79 yrs In Mandible 1) central incisor was 6.40 yrs 2) lateral incisor was 7.41 yrs 3) canine was 10.18 yrs 4) 1st premolar was 10.26 yrs 5) 2nd premolar was 11.15 yrs 6) 1st molar was 6.32 yrs 7) 2nd molar was 12.05 yrs 3. The eruption sequence of permanent teeth by Z-test was as follow: In Male 1st : Mandibular 1st molar, and Mandibular central incisor 2nd : Maxillary 1st molar 3rd : Maxillary central incisor 4th : Mandibular lateral incisor 5th : Maxillary lateral incisor 6th : Mandibular canine, Maxillary and Mandibular 1st premolar 7th : Maxillary canine 8th : Maxillary and Mandibular 2nd premolar 9th : Mandibular 2nd molar 10th : Maxillary 2nd molar In Female 1st : Mandibular 1st molar, and Mandibular central incisor 2nd : Maxillary 1st molar 3rd : Mandibular lateral incisor, Maxillary central incisor 4th : Maxillary lateral incisor 5th : Mandibular canine, Maxillary and Mandibular 1st premolar 6th : Maxillary canine 7th : Maxillary and Mandibular 2nd premolar 8th : Mandibular 2nd molar 9th : Maxillary 2nd molar 4. The corresponding permanent teeth in the mandible generally erupted earlier than the corresponding permanent teeth in the maxilla by an average of 0.73 years, but the mean eruption time of mandibular 1st premolars was almost the same as those of maxillary 1st premolars, and the mean eruption time of mandibular 2nd premolars was 0.06 years later than those of maxillary 2nd premolars. 5. There is no significant difference between left and right arch in the eruption time and sequence. 6. Generally, the ages of permanent teeth eruption tended to be earlier than those of Dr. Cha's data from 1963.

• Journal of the Korean Ceramic Society
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• v.39 no.1
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• pp.26-32
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• 2002

The effects of $Nd_2O_3$ addition to $Q{\cdot}f_{0}(GHz)$ ceramics with ${\varepsilon}_r$ of 126, $Q{\cdot}f_{0}(GHz)$ of 2240 and of $68\;ppm/^{\circ}C$ on their microwave properties were investigated. For the addition of 5 wt% $Nd_2O_3$, the dielectric constant (${\varepsilon}_r$) showed maximum value of 131, then decreased with the further addition of $Nd_2O_3$. $Q{\cdot}f_{0}(GHz)$ value was still increased to 3533 with 9 wt% $Nd_2O_3$ addition, it is influenced by densification of grain boundary. With more addition of $Nd_2O_3$ up to 18 wt%, the abnormal grain growth have influence on the decreasing of $Q{\cdot}f_{0}(GHz)$ value. But with the further addition of $Nd_2O_3$ over 25 wt%, the $Q{\cdot}f_{0}(GHz)$ value was again increased by the effect of the second phase ($Nd_2Ti_2O_7$) forming. The temperature coefficient of resonant frequency (${\tau}_f$) was decreased from $+\;68\;ppm/^{\circ}C$ with the addition of $Nd_2O_3$, reached $0\;ppm/^{\circ}C$ at 12 wt% addition, and became negative with the further addition of $Nd_2O_3$. The optimum microwave dielectric properties were obtained for $0.3CaTiO_3-0.7(Li_{1/2}Nd_{1/2})TiO_3$ with 9 wt% $Nd_2O_3$ sintered at $1425^{\circ}C$ for 3 hrs. The dielectric constant (${\varepsilon}_r$), the $Q{\cdot}f_{0}(GHz)$ value, and the temperature coefficient of resonant frequency (${\tau}_f$) were 108, 3533, and $+\;6\;ppm/^{\circ}C$, respectively.

• Journal of the Korean Magnetics Society
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• v.4 no.2
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• pp.122-125
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• 1994

The magnetic properties of Nd-Fe-B alloys of containing 4 at.% Nd have been studied for the development of new type rare-earth magnets. The amorphous phase of a melt-spun $Nd_{4}Fe_{85.5}B_{10.5}$ alloy is transformed into the phases which have a small amount of $Nd_{2}Fe_{14}B_{1}$ in ${\alpha}-Fe$ matrix by annealing above their crystallization temperature. The addition of Mo, Nb, V or Cu to $Nd_{4}Fe_{85.5}B_{10.5}$ alloy results in the reduction of grain size and the sub¬sequent improvement of the coercivity. The coercivity of $Nd_{4}Fe_{82}B_{10}M_{3}Cu_{1}$(M = Mo, Nb, V) alloys increases in the order of M = V < Nb < Mo and shows the highest value of 2.7 kOe when M = Mo. On the other hand, the rem¬anence of these alloys shows the opposite trend and the rn>st improved value of 1.35 T is observed when M = V.

• Journal of the Korean Chemical Society
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• v.39 no.9
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• pp.692-697
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• 1995

The chemical compositions and possible structure for the complex of B15C5 with Nd(Ⅲ) have been determined by NMR spectrophotometry in acetone-d6. On the stepwise additions of Nd(Ⅲ) to B15C5 solution of constant concentration, all the resonances shifted to downfield and the mole ratio of B15C5 to Nd(Ⅲ) was found to be 1 : 1. From the line broadening of proton peaks of NMR spectra, it was found that oxygen atoms in B15C5 interact with Nd(Ⅲ) ion. And in IR spectra of Nd(Ⅲ)-B15C5 complex, the band of asymmetric C-C-O stretching vibration shifted to a lower frequency region upon complexation. We have proposed the possible structure of the Nd(Ⅲ)-B15C5 coordinated with the five ether oxygen atoms and with the three bidentate nitrato groups.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2007.10a
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• pp.271-274
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• 2007

본 연구는 $1.3{\mu}m$ 파장의 초고속 Nd:YAG레이저 펄스를 얻기 위해 AOM을 이용하여 모드록킹 Nd:YAG레이저 공진기를 구성하였다. 여기용 반도체 레이저는 중심파장 810nm, 출력 1.2W이며, 레이저 매질은 직경 3mm, 길이 10mm로 $Nd^{3+}$가 1.0at%로 도핑된 Nd:YAG Rod를 사용하였다. 모드록킹에는 음향광학 변조기(변조 주파수 40MHz)를 사용하여 펄스폭 ${\tau}p=80ps$의 극초단 펄스를 얻었다.

• Progress in Superconductivity and Cryogenics
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• v.4 no.1
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• pp.21-25
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• 2002

The effect of Ca-doping on the superconducting properties of Nd-Ba-Cu-O bulk superconductors, fabricated by the oxygen-controlled melt growth process, has been systematically investigated. Various c-axis textured bulk samples were grown using precursors with the nominal compositions of $Nd_{1.8-x}Ca_{x]Ba_{2.4}Cu_{3.4}O_{y}$ (x= 0.00, 0.02, 0.05, 0.10, 0.15) in a reduced oxygen atmosphere of 1%O$_2$ in Ar. Magnetization measurements revealed that the critical temperatures(Tc) were almost linearly depressed from 95K to 86K with increasing the Ca dopant from x : 0.0 to 0.15, respectively, and thus critical current densities(Jc) at 77K and for H//c-axis of specimens were gradually degraded with increasing x. Compositional analyses revealed that although the amounts of the Ca dopant both in $NdBa_2Cu_2O_y(Nd123) and Nd_4Ba_2Cu_2O_{10}(Nd422)$,/TEX> were increased with increasing x, only less than half of the initial Ca compositions were detected in melt-grown Ca-doped Nd-Ba-Cu-O bulk crystals. The supression of Tc is attributed to an increased Nd substitution for the Ba site in the Nd123 superconducting matrix with increasing the amount of the Ca dopant.

• Journal of Korean Society of Environmental Engineers
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• v.37 no.7
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• pp.396-403
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• 2015

This study was investigated occurrence and distribution patterns of organophosphorus flame retardants (OPFRs) in Nakdong River basin (mainstream, tributaries and sewage treatment plant (STP) effluents). 3 (TCEP, TCPP and TBEP) out of 9 OPFRs were detected in 6 out of 20 sampling sites (mainstream and tributaries), The TCPP and TBEP concentration levels in mainstream samples were ND~114.9 ng/L ng/L and ND~49.1 ng/L, respectively. And the TCEP, TCPP and TBEP concentration levels in tributary samples were ND~1,865.3 ng/L, ND~519.2 ng/L and ND~210.4 ng/L, respectively. 4 (TBP, TCEP, TCPP and TBEP) out of 9 OPFRs were detected in effluents of 11 STPs around the Nakdong River basin. The TBP, TCEP, TCPP and TBEP concentration levels in 11 STP effluents were ND~458.5 ng/L, ND~2,932.7 ng/L, ND~1,320.7 ng/L and ND~655.2 ng/L, respectively. According to the sampling season, change ranges of distribution patterns and detected concentrations of OPFRs were highly variable in the same sampling sites.