• The Korean Journal of Ecology
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• 제15권1호
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• pp.1-7
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• 1992

The dvelopment of leaves in soybean(glycine max cv. yellow grain and glycine max cv. black grain)plant were assessed for the applicability of the plastochron index. The plastochron ages versus time in days were respectively 6.4 days in black grain and 9.6 days in yellow grain. Plots of plastochron indes(pi) versus time were linear, there were two distinct groups of regression line. when a point of intersection in the lines were upper than the reference length, pi was estimated n+(ln Ln-ln LR)/(ln Ln-ln Ln+2) or (n-1)+(ln Ln-1-ln LR)/(ln Ln-1-ln Ln+1) . When a point of intersection in the lines were less than the reference length, pl was estimated n+(ln Ln-ln LR)/(ln Ln-ln Ln+2) or (n-1)+(ln Ln-1-ln LR)/(ln Ln-1-ln Ln+1) . The growth rate of black grain plants analysed by pl was higher than yellow grain plants.

• 대한종양외과학회지
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• 제14권2호
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• pp.120-127
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• 2018

Purpose: The purpose of this study was to determine the immunologic role of lymph node (LN) and stage migration by assessing LN count and metastatic LN count. Methods: A total of 2,117 patients with gastric adenocarcinoma located in the body and antrum who underwent distal/subtotal gastrectomy with D2 LN dissection between January 1, 1998 and December 31, 2008 were enrolled. LN count and number of metastases were determined in the N1 tier (area of D1 dissection) and N2 tier (area of D2 dissection). The lower and upper quartiles of LN counts in the same pN stage were grouped to compare the prognosis and LN positivity according to the LN tier. Results: Stage migration from N1 tier to N2 tier occurred in 3.2% of cases. The 5-year disease-specific survival rates of the upper and lower LN count groups within the N1 tier were 91.0% and 86.7% (P=0.01), respectively. LN positivity in the N2 tier of the lower LN count group was higher than that of the upper LN count group (14.1% vs. 8.2%, P<0.01). Stage migration in the N2 tier of the lower LN count group was also higher than that of the upper LN count group (4.6% vs. 1.8%, P<0.01). Conclusion: The lower LN count group had a decreased survival rate compared to that of the upper LN count group, suggesting that perigastric LN has an immunological defense role in weakening the disseminating power of metastatic tumor cells, as indicated by the LN count.

• Bulletin of the Korean Chemical Society
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• 제34권12호
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• pp.3609-3614
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• 2013

Orthorhombic and hexagonal lanthanum(III) hydroxycarbonate ($LaCO_3OH$) and $Ln^{3+}$-doped $LaCO_3OH$ ($LaCO_3OH:Ln^{3+}$, where Ln = Ce, Eu, Tb, and Ho) powders were prepared by a hydrothermal reaction under ambient pressure and characterized by thermogravimetry, powder X-ray diffraction, infrared and luminescence spectroscopy, and field-emission scanning electron microscopy. The polymorph of $LaCO_3OH$ depended on the reaction temperature, inorganic salt additive, species of $Ln^{3+}$ dopant, and solvent. The calcination of orthorhombic $LaCO_3OH:Ln^{3+}$ (2 mol %) powers at $600^{\circ}C$ yielded a mixture of hexagonal and monoclinic $La_2O_2CO_3:Ln^{3+}$ powders. The relative quantity of the latter increased with decreasing ionic radius of the $Ln^{3+}$ dopant ion and increasing doping concentrations. On the other hand, the calcination of hexagonal $LaCO_3OH:Ln^{3+}$ (2 mol %) powders at $600^{\circ}C$ resulted in a pure hexagonal $La_2O_2CO_3:Ln^{3+}$ powder, regardless of the species of $Ln^{3+}$ ions (Ln = Ce, Eu, and Tb). The luminescence spectra of $LaCO_3OH:Ln^{3+}$ and $La_2O_2CO_3:Ln^{3+}$ were measured to examine the effect of their polymorph on the spectra.

• 전자공학회논문지D
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• 제35D권10호
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• pp.51-59
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• 1998

(Na½Ln½) TiO₃(Ln = La, Pr, Nd, Sm)은 양의 온도계수(190 ∼ 480ppm/℃), 고유전율(99∼127)의 특성을 갖고 있다. 반면에 MgTiO₃는 음의 온도계수(-45ppm/℃), 저유전손실(110,000㎓)을 갖고 있다. 그래서 xMgTiO₃(1-x) (Na½Ln½) TiO₃의 유전특성에 관심을 갖게 되었고, 초고주파 대역에서의 유전특성을 측정하고 미세구조를 관찰하여, 몰비변화와 소결온도변화에 따른 경향성을 파악하였으며, 그 원인을 연구하였다. 그 결과 MgTiO₃와 (Na½Ln½) TiO₃는 구조적으로 새로운 고용체나 이차상을 형성하지 않는 혼합상을 이루고 있었다. 그리고 이들의 유전특성은 (Na½Ln½) TiO₃와 MgTiO₃의 중간 값을 나타냈고, logarithmic mixing rule로써 유전특성을 예측할 수 있다. 이중에서 온도에 안정한 조성은 Ln = La, Pr, Nd으로 치환되었을 경우 각각 x = 0.9, 0.87, 0.84이었다. 이때의 유전율은 22 ∼25, Qf값은 55000 ∼ 28000㎓를 나타내었다. 이로써 온도에 안정한 유전특성을 갖는 새로운 유전체 재료를 개발하였으며, 특히 Ln = La으로 치환되었을 경우 다른 조성에 비하여 유전특성이 좋을 뿐아니라, 소결온도 범위가 넓어 공정상의 잇점을 가지고 있다.

• Bulletin of the Korean Chemical Society
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• 제27권11호
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• pp.1839-1843
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• 2006

Hydrothermal reactions of $Ln(NO_3)_3{\cdot}5H_2O $ (Ln = Eu (1), Sm (2), Ho (3), Dy (4)) with 3,5-pyridinedicarboxylic acid (3,5-pdcH2) in the presence of 4,4'-bipyridine led to the formation of the 3-D Ln(III)-coordination polymers with a formula unit of $[Ln_2(3,5-pdc)_2(C_2O_4)(H_2O)_4]{\cdot}2H_2O$. These polymers contain a bridging oxalate ligand ($C_2O_4\;^2$). On the basis of GCMS study of the mother liquor remaining after the reaction, we proposed that the $C_2O_4\;^2$ formation proceeds in three steps: (1) Ln(III)-mediated decarboxylation of $3,5-pdcH_2$ to give $CO_2$, (2) the reduction of $CO_2$ to $CO_2\;^{\cdot}$ by the Ln(II) species, and (3) the reductive coupling of the two $CO_2\;^{\cdot}$ radicals to the oxalate ($C_2O_4\;^2$) ion. All polymers were structurally characterized by X-ray diffraction.

• 한국잠사곤충학회지
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• 제42권1호
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• pp.1-5
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• 2000

To investigate the possibility of crypreservation of mulberry seeds in liquid nitrogen(LN$_2$), characteristics of the seeds were examined after picking mulberry syncarps and drying-heat treatment. Storage in LN$_2$has the potential of providing indifinite preservation of valuable seed germplasm. Determining the tolerance of seeds among given cultivars to LN$_2$cooling and subsequent rewarming is the first step to establishing the feasibility of LN$_2$storage. Seeds of 4 mulberry varities were treated to LN$_2$(-196$\^{C}$) for 24 hours after drying heat treatment. Seed moisture content of Daeryukppong was the highest. As moisture content of mulberry seed was below 1%, storage in LN$_2$was safe. And drying heat treatment for 60 minutes was suitable to prevent decreased germination rate and germination vigor of seeds. The seeds of Cheongilppong were unsuibable to cryopreserve in LN$_2$for longterm storage.

• Bulletin of the Korean Chemical Society
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• 제17권2호
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• pp.168-172
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• 1996

The variations of the structural detail of layered perovskite-type oxides, Na2Ln2Ti3O10 (Ln=La, Nd, Sm, Gd), have been refined by Rietveld analyses of their powder X-ray diffraction data. Although the c-axis strongly decreases from Ln=La to Nd, Sm, or Gd, the length of Na-O bond along the c-axis that is regarded as the sodium layer spacing is not dependent on the unit cell parameter. Such a behavior is explained by the fact that Na-O bond is in competition with Ti-O one of the perovskite slab. Increased covalency of this Ti-O bond by the lattice contraction leads to weakening of the attaching strength of Na ion. This picture is consistent with the experimental observation that Na ion conductivity of Na2Ln2Ti3O10 increases from Ln=La to Nd, Sm, or Gd despite strong contraction of the unit cell volume.

• 대한화학회지
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• 제43권3호
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• pp.257-263
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• 1999

2,6-diformyl-p-creso1(DFPC)로부터 합성한 Ln-거대고리([20]DOTA) 착물, [Ln([20]DOTA)(NO3)(H2O)](NO3)2 xH2O{Ln(III)=Pr, Sm, Gd, Dy}를methanol용매에 2일정도 정치함으로써 [Ln([20]DOTA)(NO3)(CH3OH)]2+을 얻을 수 있다. 이 lanthanide-거대고리 착물에서 배위 된 CH3OH이 주게원자가 N인 보조리간드,La(=한자리 리간드;pyidine, imidazole, triethylamine, diethylamine, piperidine)에 의해 치환될 때 평형상수(K)를 25 oC, ㅒ=0.1M에서 분광학적 방법으로 결정하였다. 보조리간드의 pKa는 pyridine

• Bulletin of the Korean Chemical Society
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• 제34권11호
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• pp.3420-3424
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• 2013

The reaction of $LnCl_3{\cdot}7H_2O$ [Ln = La (1), Ce (2)] with salicylic acid (HL) and 1,10-phenanthroline (Phen) at $20^{\circ}C$ in $H_2O$/ethanol gave after work-up and recrystallization two novel lanthanide complexes with general formula $[Ln(Phen)_2(L)_3(HL)]{\cdot}H_2O$. Compounds 1 and 2 were characterized by IR and UV-Vis spectroscopy, TGA, CHN as well as by X-ray analysis. According to these results, compounds 1 and 2 are isostructural and contain $Ln^{3+}$ ions with coordination number nine. Complexes 1 and 2 consist of two Phen, one neutral HL and three L anions (two L anions act as monodentate ligands and the third one is chelating to $Ln^{3+}$). Thermal decomposition led to primary loss of the Phen molecules. Then HL molecules and finally L moieties left the material to give $Ln_2O_3$.

• 대한안전경영과학회:학술대회논문집
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• 대한안전경영과학회 2002년도 춘계학술대회
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• pp.207-214
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• 2002

This paper presents some physical evidences indicating that reduced friction occurs in an cryogenic machining process, in which LN2 is applied selectively in well-controlled jets to the selected cutting zone. In machining tests, cryogenic machining reduced the force component in the feed direction, indicating that the chip slides on the tool rake face with lower friction. This study also found that the effectiveness of LN2 lubrication depends on the approach how LN2 is applied regarding cutting forces related.