• The Korean Journal of Ceramics
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• v.5 no.2
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• pp.178-182
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• 1999

Simple binary $Na_2S-SiO_2$ oxysulfide glasses were prepared by a conventional melt-quench method in order to investigate the role of sulfur in glass structure and the electronic state. By X-ray photoelectron spectroscopy(XPS) measurement, S2p binding energy of the glass was observed at approximately 161eV which was close to that of ionic $S^{2-}$. The coordinating state around silicon atoms were investigated by ${29}^Si$ MAS-NMR measurement. The chemical shift observed from NMR supported that sulfur atom was joined to a silicon atom by substituting for an oxygen atom and was present as a non-bridging sulfide ion in low alkali content. On the other hand, it could be presumed that a portion of sulfur anions existed in an isolated state from the glass-network frame at high alkali content. The state of these sulfurs was also studied by Raman spectroscopy in detail.

• Proceedings of the Korea Concrete Institute Conference
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• 2008.04a
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• pp.917-920
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• 2008

ECC is a special kind of high performance cementititous composite which exhibits typically more than 2% tensile strain capacity by bridging microcracks at a crack section. Therefore, micromechanics should be adopted to obtain multiple cracking and strain hardening behavior. This paper propose a linear elastic analysis method to simulate the multiple cracking and strain hardening behavior of ECC. In an analysis, the stress-crack opening relation modified considering the orientation of fibers and the number of effective fibers is adopted. Furthermore, to account for uncertainty of materials and interface between materials, the randomness is assigned to the tensile strength(${\sigma}_{fci}$), elastic modulus($E_{ci}$), peak bridging stress(${\sigma}_{Bi}$) and crack opening at peak bridging stress(${\delta}_{Bi}$), initial stress at a crack section due to chemical bonding, (${\sigma}_{0i}$), and crack spacing(${\alpha}_cX_d$). Test results shows the number of cracking and stiffness of cracked section are important parameters and strain hardening behavior and maximum strain capacity can be simulated using the proposed method.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.17 no.8
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• pp.69-76
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• 2016

As the number of SNS users increases, so does their self-disclosure. This study examined the factors affecting self-disclosure based on Social Capital Theory and Regulatory Focus Theory. The (extent of self-disclosure by users/number of users disclosing themselves) in SNSs is expected to differ depending on their social capital (bonding capital vs. bridging capital) and regulatory focus (promotional vs. defensive). As a result of this study, it is found that bridging capital is positively related to self-disclosure in profile and in conversation, while bonding capital is positively related to self-disclosure only in conversation. With regard to regulatory focus, promotional orientation has a significant effect on self-disclosure in profile and in conversation, while defensive orientation is negatively related to self-disclosure in profile, but not related to self-disclosure in conversation. Promotional orientation is found to moderate the effect of bridging capital on self-disclosure.

• Korean journal of communication and information
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• v.78
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• pp.7-34
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• 2016

The purpose of this study is to examine the factors that influence the risk perception of reality on social media. Specifically, we analyzed how exposure to risk issues through media and bridging/bonding social capital influence social and personal risk perception. Here, we categorized risk issues into infectious diseases, sex crimes, and radioactive contamination. Findings are as follows. The effect that the type of media and social capital have on risk perception vary depending on the risk issues. Regarding issues of disease and radiation, bridging social capital had a positive effect on social risk perception whereas bonding social capital had a negative effect on personal risk perception. In the case of sex crimes, bonding social capital affected both social and personal risk perception negatively, and an interaction effect between exposures and social capital could be found. The significance of this study is that it considers both media variables from previous studies and social capital variables essential to social media studies and combines the two in order to study the factors that influence risk perception.

• Analytical Science and Technology
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• v.20 no.2
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• pp.124-130
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• 2007

In this study, we present the preparation and characterization of oxidized fullerene and fullerene dimer [$C_{120}$]. From the XRD data, other weak peaks with pristine fullerene [$C_{60}$] peaks were observed in the X-ray diffraction patterns for fullerene dimer [$C_{120}$]. SEM micrographs for the fullerene dimer [$C_{120}$] indicated that practically all the surface state was shown the drastic morphology changes and its outer surface is clearly visible and resulted in clogging and frost-like formation. From the MALDI-TOF mass spectra, the differences in the spectra recorded on two kinds of fullerene are due to the oxidation including chemical bonding and bridging between the $C_{60}$ molecules. We also obtained additional information from FT-IR spectra on functional component on the chemically modified surface of oxidized fullerene and fullerene dimer [$C_{120}$].

• Proceedings of the Polymer Society of Korea Conference
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• 2006.10a
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• pp.295-295
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• 2006

In present study, poly(acrylic acid) (PAA) and hydrophobically modified poly(ethylene oxide) (HM-PEO) multilayers based on the hydrogen bonding between the component polymer pair have been prepared by the LbL deposition method. Dip assembled HM-PEO/PAA multilayers yield unique film morphologies in comparison with PEO/PAA multilayers due to the micellar formation of HM-PEO owing to the hydrophobic attraction between alkyl chains end-capped with the PEO chains. Individual HM-PEO micelles were connected through the bridging PEO chains to form temporary networks on multilayer surface and induced peculiar surface morphology on HM-PEO/PAA multilayers above the critical number of bilayers.

• Bulletin of the Korean Chemical Society
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• v.20 no.10
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• pp.1149-1152
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• 1999

1H NMR spectrum of a DMF-d7 solution containing 4-aminopyrimidine and [SiW11CoIIO39]6- (SiW11Co) shows separate peaks from two linkage isomers, a and b, in which N(1) and N(3) of the pyrimidine ring are coordinated to SiW11Co, respectively. The signal from the amine group in the isomer a exhibits temperature dependence that is characteristic of a two-site exchange problem. Rates of internal rotation of the amine group were determined by simulating the NMR spectra at 5-35℃. The amine group of free 4-aminopyrimidine also shows temperature-dependent spectra at lower temperatures; rates of internal rotation at (-25)-25℃ were determined. The internal rotation of the amine group in the complex is much slower than that for free 4-aminopyrimidine, indicating that π-character of the C-N bond increases on coordination to SiW11Co. The amine group in the isomer b does not show such behavior. It is probable that hydrogen bonding between N-H and a bridging oxygen atom of SiW11Co prevents it from rotating at low temperatures.

• Analytical Science and Technology
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• v.18 no.5
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• pp.391-395
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• 2005

The title complex, $[Cd(N_3)_2(2-ethylimidazole)_2]$, I, has been prepared and characterized by X-ray single crystallography. The complex I crystallizes in the monoclinic system, Cc space group with a = 16.200(3), b = 12.926(3), $c=7.007(1){\AA}$, ${\beta}=102.29(3)^{\circ}$, $V=1433.7(5){\AA}^3$, Z = 4, $R_1=0.0239$ and ${\omega}R_2=0.0604$ for 1874 independent reflections. Cd(II) atom has a slightly distorted octahedral coordination geometry, with four end-on (${\mu}-1$,1) bridging azido ligands and two 2-ethylimidazole ligands bonding through nitrogen atom. The central cadmium(II) atoms are run in parallel to the c-axis and are doubly bridged with neighboring cadmium(II) atoms by the end-on (${\mu}-1$,1) bridging azido ligands. Thus, this complex has a one-dimensional zigzag chain structure in which the 2-ethylimidazole is in the cis conformation.

• The Journal of the Korea Contents Association
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• v.22 no.8
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• pp.258-273
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• 2022

This study examines the effect of SNS tourism value (economic, social) and social capital (bonding, bridging) on SNS tourism satisfaction using SNS and the effect of SNS tourism satisfaction on reuse intention. In addition, in the relationship between SNS tourism satisfaction and reuse intention, a future-oriented time perspective variable was applied to investigate the moderating effect. We verified 326 people who had accommodation tourism experience using SNS. SPSS 25.0 and Smart PLS 3.0 were used to analyze reliability and validity. The study results are as follows. First, economic and social values had a positive effect on satisfaction. Second, it was found that bridging social capital had a positive effect on satisfaction, but bonding social capital had no effect. Third, satisfaction was confirmed to have a positive effect on reuse intention. Fourth, in the relationship between satisfaction and reuse intention, the future-oriented time perspective was found to have a significant moderating effect. The overall implications are presented through the research results, and it is expected that these will be used as basic data for the development plan of the tourism industry.

• Journal of Service Research and Studies
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• v.14 no.3
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• pp.60-78
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• 2024

Social Network Service(SNS) has fundamentally changed the scope, boundaries, and dynamics of social interactions, becoming an integral part of everyday social communication for individuals and significantly altering the decision-making processes of individuals and organizations. Although prior studies have agreed that individual motivations significantly affect travel experience sharing behavior on SNS, different motivations need to be further examined. Also, there is little empirical study that examines the relationships between social capital and motivations. To address these gaps, this study developed a research model to investigate how two types of social capital (i.e., bridging and bonding) influence individual motivations (i.e., self-enhancement and altruism motivations), which in turn contributes to travel experience sharing behavior on SNS. The online survey was conducted from March 3 to March 17, 2021, and 516 responses were included in the data analysis. Structural Equation Modeling was applied to test the hypotheses in a research model. This research provided a comprehensive exploration of the relationship between motivations and social capital, contributing to a better understanding of why tourists share their travel experiences on SNS.