• The Journal of Asian Finance, Economics and Business
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• 제7권5호
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• pp.305-314
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• 2020

The paper explores the return migration choice of graduates, which takes place during the transition from higher education to the labor market. Graduate students, after a short time in temporary migration to cities for studying, have to make a decision of returning back home or staying in migration in urban areas for working. Drawing on the mechanism identified in the literature on internal migration, this empirical research tests the effects of two factors: place attractiveness and social supports factors on graduates' decision to return migration to hometown. A binary logit regression analysis was conducted with data from 502 surveyed graduates in Hanoi, Vietnam. The analysis of the motives reported by graduates indicates that return migration decisions cannot be reduced to a single dimension. Perceived attractiveness of a region such as quality of living environment, job opportunities, and social context of individuals positively impact on student' decision to return migration after graduation. The research results imply that, in a collectivistic country like Vietnam, students' choice of future career is strongly influenced by their social context, and choosing a place to work is not simply a matter of earning a higher salary or enjoying better working conditions, but is also related to family issues.

• Applied Science and Convergence Technology
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• 제24권6호
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• pp.224-227
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• 2015

Ferroelectric $Pb_2(Sc,Nb)O_6$ were prepared under two different sintering conditions using the oxide mixing method and the electrical properties were measured. The sintering conditions were $1350^{\circ}C$ for 25 minutes and $1400^{\circ}C$ for 20 minutes. EDX spectroscopy and XRD were used to determine the crystalline characteristic of the $Pb_2(Sc,Nb)O_6$ compositions Pyrochlore phase showed about 2% in all $Pb_2(Sc,Nb)O_6$ specimens. It expands the growth of crystals in samples sintered at $1400^{\circ}C$ than $1350^{\circ}C$, but all samples were the optimal crystallization. The temperature and frequency dependence of the complex dielectric constant and admittance were measured to analyze the electrical properties. The high dielectric constant of the specimens reflects the good stoichiometry and crystallization. The maximum value of the dielectric constant in the two specimens treated with sintering at $1350^{\circ}C$ and $1400^{\circ}C$ were more than 27,000, and the dielectric loss at room temperature is smaller than 0.05. The maximum dielectric constant decreased with increasing frequency, the transition temperature also increased in $Pb_2(Sc,Nb)O_6$ compositions. The admittance and susceptance values reach a peak at all temperatures, and the magnitude of the peak increases with increasing measuring temperature. Strong frequency dependent of maximum admittance, susceptance, dielectric constant and dielectric loss were observed.

• 대한수학교육학회지:학교수학
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• 제11권4호
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• pp.707-722
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• 2009

이 논문에서는 최근 유럽, 특히 프랑스에서 많은 연구자들에 의해 고려되어지고 있는 수학 교육의 다양한 이론들을 소개한다. 그 중에서도 Chevallard (1985;1992;1998)에 의해 논의되었던 교수학의 인류학적 이론(The Antro-pological Theory of the Didactic)에 대해 간단히 소개한 다음, 이것에 의해 제안된 인식론적 모델인 인간행동학(Praxeology)에 대해 논의한다. 또한 교수학에 인류학을 도입해야 하는 필요성과 이 이론이 어떻게 교수학적 변환 과정을 통하여 발전되었는지 그 배경과 교수학의 인류학적 이론의 기본 요소들을 제시된다. 마지막으로 '수열의 극한' 교수에 대한 문제를 이 이론에 근거하여 분석한다.

• 아동학회지
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• 제26권1호
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• pp.317-328
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• 2005

This study investigated the effects of mothers' perceived social support, stress, and children's temperament on parenting self-efficacy of boy's and girl's mothers among 416 Korean mothers living in Seoul, Korea. Results showed that mothers' parenting self-efficacy of boys and girls were positively related to mothers' perceived social support and children's temperament. On the other hand, parenting self-efficacy of both boys' and girls' mothers were negatively related to mothers' stress. Multiple regression indicated that mothers' perceived social support and children's temperament were the significant predictors for mothers' parenting self-efficacy of boys and girls. Husbands' support, support from social network, approach-withdrawal, and activity level-general were the significant predictors for mothers' parenting self-efficacy of boys. Husbands' support, support from social network, conflict with their children, transition of husband's job, difficulty of finance and business were the significant predictors for mothers' parenting self-efficacy of girls. Husbands' support was the strongest predicator of mothers' parenting self-efficacy of boys and girls.

• Macromolecular Research
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• 제13권6호
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• pp.491-498
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• 2005

Fluorene-containing, spiro-type, conjugated polymers were synthesized via the cyclopolymerization of dipropargylfluorenes (2-substituted, X=H, Br, Ac, $ NO_{2}$) with various transition metal catalysts. The polymerization of dipropargylfluorenes proceeded well using Mo-based catalysts to give a high polymer yield. The catalytic activities of the Mo-based catalysts were found to be more effective than those of W-based catalysts. The palladium (II) chloride also increased the polymer yield of the polymerization. The polymer structure of poly(dipropargylfluorene)s was characterized by such instrumental methods as NMR ($^{1}H_{-}$, $^{13}C_{-}$), IR, UV-visible spectroscopies, and elemental analysis as having the conjugated polymer backbone bearing fluorene moieties. The $^{13}C_{-}$NMR spectral data on the quaternary carbon atoms in polymers indicated that the conjugated cyclopolymers have the six-membered rings majorly. The poly(dipropargylfluorene) derivatives were completely soluble in halogenated and aromatic hydrocarbons such as methylene chloride, chloroform, benzene, toluene, and chlorobenzene. The poly(dipropargylfluorene) derivatives were thermally more stable than poly(dipropargylfluorene) itself, and X-ray diffraction analyses revealed that the polymers are mostly amorphous. The photoluminescence peaks of the polymers were observed at about 457-491 nm, depending on the substituents of fluorene moieties.

• 반도체디스플레이기술학회지
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• 제11권4호
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• pp.37-42
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• 2012

Nanoimprint lithography (NIL) has attracted broad interest as a low cost method to define nanometer scale patterns in recent years. A major disadvantage of thermal NIL is the thermal cycle, that is, heating over glass transition temperature and then cooling below it, which requires a significant amount of processing time and limits the throughput. One of the methods to overcome this disadvantage is to improve the cooling performance in NIL process. In this paper, the performance of the cooling system of thermal NIL is numerically investigated by SolidWorks Flow Simulation program. The calculated temperatures of nanoimprint device were verified by the measurements. By using the analysis model, the effects of the change of flow velocity and cooler location on the cooling performance are investigated. For the 6 cases (0.1 m/s, 0.5 m/s, 1 m/s, 3 m/s, 5 m/s, 10 m/s) of flow velocity and for the 6 cases of distances (50 mm, 40 mm, 30 mm, 20 mm, 10 mm, 1 mm) of cooler location, the heat conjugated flow analyses are performed and discussed.

• Journal of Applied Biological Chemistry
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• 제43권3호
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• pp.156-160
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• 2000

The possible mechanism of the DNA strand breaking activity of the hot-water extract of Fructus Chaenomelis (dried fruit of Chaenomeles sinensis) in a closed circular duplex replica form DNA (RFI DNA) was studied through agarose gel electrophresis under various conditions. Induction of DNA strand scission by the hot-water extract of C. sinensis occurred in dose and time-dependent manners. $Cu^{2+}$ was indispensable for the induction of DNA strand breakage. Exogeneous chelating agents inhibited the DNA breaking activity, conforming the catalytic action of $Cu^{2+}$ on generation of free radicals responsible for oxidative damage. Antioxidant enzymes and some radical scavengers were used to investigate the major radical species triggering the DNA strand scission, demonstrating that a highest inhibitory activity was found in the presence of catalase, while less in the presence of tiron (a scavenger for superoxide radical), 2-aminoethyl-isothiuroniumbromide-HBr, cysteamine (scavengers for hydroxyl radical), and 1,4-diazabicyclo [2,2,2] octane (a scavenger for singlet oxygen) in decreasing order. The findings implied that oxygen radical species generated in presence of transition divalent cation during the oxidation of some compounds contained in the hot-water extract of C. sinensis is mainly responsible for inducing genotoxicity.

• The Journal of Asian Finance, Economics and Business
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• 제7권10호
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• pp.87-94
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• 2020

This study aims to evaluate the effectiveness of sterilization in Vietnam. We estimate a simultaneous equation by using Two-Stage least squares (2SLS) regression analysis. The time-series data was collected for the first quarter of 2004 to the fourth quarter of 2018. In particular, the effectiveness of sterilization is considered in terms of dollarized economy, since making the transition from a centrally planned to a market economy system, the Vietnamese economy has remained in a state of dollarization. In addition, we also assess whether the global financial crisis had an impact on the sterilization effectiveness of the State Bank of Vietnam (SBV). On the basis of the estimated sterilization and offset coefficients, our results suggest that the State Bank of Vietnam (SBV) has not been able to fully neutralize the impact on the domestic money supply when intervening in the foreign exchange market, and the capital inflows respond strongly to changes in domestic monetary conditions. The results also show that the global financial crisis has changed the effectiveness of these sterilization policies. An analysis of this study's empirical findings provides the opportunity to derive some recommendations that may assist in increasing the effectiveness of the State Bank of Vietnam's sterilization policies in the process of accumulating international reserves.

• Transactions on Electrical and Electronic Materials
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• 제9권2호
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• pp.47-51
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• 2008

In this paper, thermal stability of Nickel silicide formed on p-type silicon wafer using Ni-V alloy film was studied. As compared with pure Ni, Ni-V shows better thermal stability. The addition of Vanadium suppresses the phase transition of NiSi to $NiSi_2$ effectively. Ni-V single structure shows the best thermal stability compared with the other Ni-silicide using TiN and Co/TiN capping layers. To enhance the thermal stability up to $650^{\circ}C$ and find out the optimal thickness of Ni silicide, different thickness of Ni-V was also investigated in this work.

• 반도체디스플레이기술학회지
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• 제10권1호
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• pp.95-99
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• 2011

$(1-x)BaTiO_3+(x)Cd_5(PO_4)_3Cl$ ceramics were prepared by the conventional ceramic technique, i.e., solid state reaction at high temperature. The concentration of $Cd_5(PO_4)_3C$ was varied from 0.01 to 0.15 mole fraction. In order to study the phase transitions of our ceramics, the Raman scattering spectra were measured as functions of concentration x and temperature. It was found that the soluble limit of $Cd_5(PO_4)_3Cl$ in $BaTiO_3$ was the x=0.05 composition and $BaTiO_3$ phase disappeared above x=0.10. A new phase identified as $Ba_4Ti_3P_2O_{15}$ was detected in all samples of our compositions. The Curie temperature shifts up to $130^{\circ}C$ as the concentration x increases from zero to 0.05 and shift down to $95^{\circ}C$ as further increases to 0.08. For the increase of the Curie temperature, it is suggested that it can result from the inhibition of displacement of $Ti^{4+}$ in the distorted octahedron due to well dispersed $Ba_4Ti_3P_2O_{15}$ and $Cd_5(PO_4)_3Cl$ phase.