• 통합자연과학논문집
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• 제6권2호
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• pp.104-110
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• 2013

1-Aza-12-crown-4 macrocyclic ligand was combined with styrene (2th petroleum in 4th class hazardous materials) divinylbenzene copolymer having 1%, 2%, 3%, and 6% crosslinks by a substitution reaction, in order to synthesize resin. These synthetic resins were confirmed by chlorine content, elementary analysis and IR-spectrum. As the results of the effects of pH, equilibrium arrival time, crosslink of synthetic resin, and dielectric constant of a solvent on uranium ion adsorption for resin adsorbent, the uranium ion showed high adsorption at pH 3 or over and adsorption equilibrium of uranium ion was about 2 hours. In addition, adsorption selectivity for the resin in methanol solvent was the order of uranium ($UO_2{^{2+}}$) > iron ($Fe^{3+}$) > lutetium ($Lu^{3+}$) ions, adsorbability of the uranium ion was in the crosslinks order of 1%, 2%, 3%, and 6% was increased with the lower dielectric constant.

• 한국세라믹학회지
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• 제33권10호
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• pp.1131-1137
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• 1996

The dielectric properties and phase stabilities of Pb(Zn0.6Mg0.4)1/3Nb2/3O3 [PZMN]system were investigated into substitution of A-site with Ba, Sr and Ca ions. The A-site substitutions led to the complexity of components of perovskite phase and then DPT coefficient increased. The A-site substitutions of Ba or Sr ion perovskite single phase could be easily formed by columbite process due to increase of perovskite phase stability. The variation of lattice parameters in specimen obeyed Vegard's law and curie temperature and dielectric constant of specimen decreased linearly. But Ca substitution led to perovskite phae instability. The lattice parameter dielectric constant and curie temperature of specimens drasticaly decreased with formation of pyrochlore phase.

• Journal of Electrochemical Science and Technology
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• 제15권1호
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• pp.161-167
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• 2024

Despite the important role of manganese (Mn) in cobalt-free, Ni-rich cathode materials, existing reports on the effects of Mn as a substitute for cobalt are not consistent. In this work, we analyzed the performance of cathodes comprised of Li(Ni_1-xMn_x)O₂ (LNMO). Both beneficial and detrimental results occurred as a result of the Mn substitution. We found that a complex interplay of effects (Li/Ni mixing driven by magnetic frustration, grain growth suppression, and retarded lithium insertion/extraction kinetics) influenced the performance and was intimately related to calcination temperature. This indicates the importance of establishing an optimal reaction temperature for the development of high-performance LNMO.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2002년도 가을 학술발표회 논문집
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• pp.17-22
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• 2002

Chloride ions have a tendency to penetrate into concrete and proceed the corrosion by depassivating rebar surface. Thus the deteriorated concrete is subject to experience severe degrading of durability under marine environment. Physical properties of mortar, such as, compressive strength and penetration depth of chloride ion were investigated. And to investigate the effect of containing SG, FA in mortar, the diffusion coefficient of chloride was measured through an electro - migration test. The diffusion coefficient of chloride was decreased with the increase of replacement ratio of SG compared with plain specimen.

• 한국결정성장학회지
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• 제8권1호
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• pp.160-168
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• 1998

치환에 의한 wagnerite의 색상변화 및 고용체 형성한계를 살펴보기 위해 wagnerite ($A_2XO_4Z$)를 합성한후 각 구성원소들을 치환하였다. Ca-wagnerite의 Ca 대신에 Mg, Co, Ni, Cu로 치환하여 용해도가 한정된 고용체를 얻었다. 이들 중 (Mg,Ca)-wagnerite와 (Co,Ca)-wagnerite의 경우에만 단일상의 wagnerite를 합성하였으며 이들의 색상은 각각 백색과 자주색이었다. 그 외의 조성 및 (Ni,Ca)-wagnerite와 (Cu,Ca)-wagnerite의 경우에는 여러상이 혼재해 있는 것으로 나타났다. $A^{5+}$자리에 Li을 치환해 보았으며 또한 $X^{5+}$대신 V을 치환하여 진한 자주 및 금색, 옅은 노란색의 wagnerite를 합성하였으며, Z- 대신 Cl을 치환한 경우 단일상의 wagnerite을 얻지 못하였다.

• Progress in Superconductivity
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• 제13권3호
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• pp.163-168
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• 2012

The effects of Ta substitution on the superconducting and magnetic properties of the $(Ru_{1-x}Ta_x)Sr_2(Gd_{1.4}Ce_{0.6})Cu_2O_z(0{\leq}x{\leq}0.5)$ system have been investigated. The X-ray diffraction measurements indicate that the Ta ion replaces Ru sites up to x = 0.4. It is found that the Ta substitution for Ru significantly reduces the weak-ferromagnetic component of the field-cooled magnetic susceptibility without an appreciable change of room temperature thermopower at lower Ta doping level below x = 0.2. The resistive transition temperature tends to decrease monotonically from 27 K for the x = 0 sample to 16 K (9 K) for the x = 0.4 (x = 0.5) sample. These results suggest that superconductivity of the $(Ru_{1-x}Ta_x)Sr_2(Gd_{1.4}Ce_{0.6})Cu_2O_z$ compound is not significantly affected by the magnetic state of the Ru sublattice. The experimental results are discussed in connection with previous reports on the effects of Nb substitution.

• 한국세라믹학회지
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• 제34권8호
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• pp.897-907
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• 1997

Thin films of Bi4-xSmxTi3O12(0$\leq$x$\leq$2) were prepared on Pt/Ti/SiO2/Si(100) at $700^{\circ}C$ using spin-coating with sols derived from Bi-Sm-Ti complex alkoxides. From X-ray diffraction analysis, it was observed that Sm-substituted phases resembled ferroelectric Bi4Ti3O12 in structure. Variations of their lattice parameters depending on the amount of Sm-substitution showed that an anomalous structural distortion might exist at x=1. The grain sizes of the thin films decreased from 0.115 ${\mu}{\textrm}{m}$ to 0.078${\mu}{\textrm}{m}$ with increasing the amount of Sm-substitution. The dielectric constants and the remanent polarizations of the thin films decreased with increasing the amount of the Sm-substitution, which were related to decrease of the stereo-active Bi3+ ion contributing to polarization. However, these values were exceptionally high at x=1, compared to those of the other substituted phases. Such an anomaly suggests that the phase of x=1 has 1:1 chemical ordering between Sm and Bi in structure. The thin films of all compositions except x=2 showed ferroelectricity. The thin film of x=2 was paraelectric, whose grains were too fine to exhibit ferroelectricity.

• 한국세라믹학회지
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• 제23권1호
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• pp.7-12
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• 1986

Dielectric properties of $Ba_{0.9}Ca_{0.1}(Ti_{1-x}Sn_x)O_3$ were investigated from x=0 to 0.20, and temperature range -4$0^{\circ}C$~13$0^{\circ}C$ Density and grain size decreased with increasing Sn content due to grain growth inhibitor. Dielectric constant below the Curie temperature increased with increasing Sn content and dissipation factor dec reased. These results are due to grain size effect and internal stress. Curie temperature was shifted to lower temperature with increasing ratio of total polarizability to volume resulting from substitution of $Ba^{2+}$ ion with $Ca^{2+}$ ion $Ti^{4+}$ ion with $Sn^{4+}$ ion.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2018년도 춘계 학술논문 발표대회
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• pp.54-55
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• 2018

Reinforced concrete is a building material that is generally used in modern society. Securing the performance of reinforced concrete is directly connected to the durability and longevity of the building. One of the major factors that deteriorate the durability of concrete is harmful ion. Recently, the quality and improvement method of reinforced concrete for penetration of harmful ion has been studied. In this study, the bead type ion exchange resin is substituted for 0%, 3%, and 6% of the fine aggregate volume in the mortar. The speciments underwent underwater curing and were checked for compressive strengths of 3 days and 28 days. From the results of compressive strength, it can be seen that the higher the substitution ratio of the ion exchange resin, the lower the early strength and long-term strength development, especially the early strength development.

• Bulletin of the Korean Chemical Society
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• 제35권5호
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• pp.1506-1510
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• 2014

A kinetic study on nucleophilic substitution reaction of 5-nitro-8-quinolyl picolinate (6) with alkali-metal ethoxides (EtOM; M = K, Na, and Li) in anhydrous ethanol is reported. The plot of $k_{obsd}$ vs. [EtOM] curves upward in the absence of crown ethers but is linear with significantly decreased reactivity in the presence of crown ethers. Dissection of $k_{obsd}$ into $k_{EtO}$- and $k_{EtOM}$ (i.e., the second-order rate constants for the reactions with the dissociated $EtO^-$ and ion-paired EtOM, respectively) has revealed that the ion-paired EtOM is significantly more reactive than the dissociated $EtO^-$ (e.g., $k_{EtOM}/k_{EtO^-}$ = 33.4-141). This indicates that the reaction of 6 is catalyzed by $M^+$ ions in the order $Na^+$ > $Li^+$ > $K^+$ and the catalytic effect disappears in the presence of a proper crown ether. Picolinate ester 6 is much more reactive and is more strongly catalyzed by $M^+$ ions than 5-nitro-8-quinolyl benzoate (5). It has been concluded that $M^+$ ions catalyze the reaction of 6 by increasing electrophilicity of the reaction center through a cyclic transition state, which is structurally not possible for the reaction of 5.