• Bulletin of the Korean Chemical Society
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• v.22 no.2
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• pp.213-218
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• 2001

Presented are the STM images of self-assembled monolayer of 2-mercaptoethanol on Au(111). Striped structures of ($6{\times}3_{\frac{1}{2}}$), ($5{\times}3_{\frac{1}{2}}$), ($4{\times}3_{\frac{1}{2}}$) and compact-($5{\times}3_{\frac{1}{2}}$) were observed after annealing at $80^{\circ}C.$ Analysis of the ordered structures revealed that the basic fundamental units of the ordered structures were three crystallographically non-equivalent ($3_{\frac{1}{2}}{\times}3_{\frac{1}{2}}$) $R30^{\circ}$ assemblies, and that the way of combination of the assemblies produced the four different structures. The($6{\times}3_{\frac{1}{2}}$) structure ( $\theta$ = 0.33) was composed of one ($3_{\frac{1}{2}}{\times}3_{\frac{1}{2}}$)$R30^{\circ}$ assembly, while the ($5{\times}3_{\frac{1}{2}}$) ( $\theta$ = 0.30) and ($4{\times}3_{\frac{1}{2}}$) ( $\theta$ = 0.38) structures were consisted of two ($3_{\frac{1}{2}}{\times}3_{\frac{1}{2}}$) $R30^{\circ}$ assemblies, separated by 5a and 4a, respectively. Furthermore, the compact-(5X 3½) structure ( $\theta$ = 0.50) was obtained by overlapping three ($3_{\frac{1}{2}}{\times}3_{\frac{1}{2}}$) $R30^{\circ}$ assemblies. In spite of the diversity in the adsorption structures, all the adsorption sites of 2-mercaptoethanol were fundamentally identical. On the other hand, the unannealed primitive SAM of 2-mercaptoethanol was characterized by two observations: a short-range order keeping the adsorbed molecules at approximately $3_{\frac{1}{2}}$ a and the small domains of the striped structures supporting that the observed surface structures on the annealed surface were the extension of the primitive layer of 2-mercaptoethanol. Comparing these observations with the already published structures of ethanthiol, it was concluded that the interaction between the hydroxyl groups of 2-mercaptoethanol might play a significant role in the adsorption step of 2-mercaptoethanol on Au(111) to organize the adsorption structures different from those of ethanthiol.

• Korean Journal of Materials Research
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• v.27 no.10
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• pp.534-543
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• 2017

$Gd_2O_3:Eu^{3+}$ red phosphors were prepared by template method from crystalline cellulose impregnated by metal salt. The crystallite size and photoluminescence(PL) property of $Gd_2O_3:Eu^{3+}$ red phosphors were controlled by varying the calcination temperature and $Eu^{3+}$ mol ratio. The nano dispersion of $Gd_2O_3:Eu^{3+}$ was also conducted with a bead mill wet process. Dependent on the time of bead milling, $Gd_2O_3:Eu^{3+}$ nanosol of around 100 nm (median particle size : $D_{50}$) was produced. As the bead milling process proceeded, the luminescent efficiency decreased due to the low crystallinity of the $Gd_2O_3:Eu^{3+}$ nanoparticles. In spite of the low PL property of $Gd_2O_3:Eu^{3+}$ nanosol, it was observed that the photoluminescent property was recovered after re-calcination. In addition, in the dispersed nanosol treated at $85^{\circ}C$, a self assembly phenomenon between particles appeared, and the particles changed from spherical to rod-shaped. These results indicate that particle growth occurs due to mutual assembly of $Gd(OH)_3$ particles, which is the hydration of $Gd_2O_3$ particles, in aqueous solvent at $85^{\circ}C$.

• Journal of the Korean Chemical Society
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• v.51 no.6
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• pp.526-535
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• 2007

Ru(II)-terpyridine complexes (8, 9, 11) linked with adamantyl or β-cyclodextrin moieties were synthesized and characterized based on their 1H and 13C NMR spectra as well as MS spectra. Ru(II)-terpyridine complexes (8, 11) linked with adamantyl moiety were readily dissolved in aqueous solution via encapsulation by β-cyclodextrin when they were mixed with an equimolar amount of β-cyclodextrin. In the similar way, the adamantane guest of the Ru(II)-terpyridine complexes (8, 11) were encapsulated by β-cyclodextrin moiety of the ruthenium complex 9 to afford supramolecular assemblies in aqueous environment. Formation of assemblies was corroborated by 1H NMR spectroscopy.

• Journal of Convergence for Information Technology
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• v.7 no.6
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• pp.53-59
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• 2017

This study was attempted to identify the domestic research related to depression and stress. The subjects of the analysis were 1,875 college degree theses thrown in the National Assembly Library searched by the depression and stress keyword as of November 30, 2016. The analysis method visualizes atypical data with Word Cloud, which is one of the text mining techniques. We also used the R'LDA package and LDA to classify treatment and subjects. As a result of the analysis, 233(12.4%) of the total papers with therapeutic keywords were found. Application of treatment methods was art therapy, music therapy, horticultural therapy, cognitive behavior therapy, clinical art therapy, cognitive therapy, psychological therapy, depression treatment, group therapy, laughter treatment sequence. The study subjects were adolescents, elderly, patient, mother, child, female, parents, and college students in order. The results of LDA topic analysis for adolescents were classified into four topics: self-support, treatment program, relationship effect, and variable study.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.8 no.1
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• pp.96-102
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• 2007

Welding deformation causes critical problems under construction and in use of steel structures by varying the magnitude of the steel structures and deteriorating mechanic strength. Existing method to construct steel structures in civil engineering needs preassembly process for a part of or the whole structures on a broad space to examine the size of structures inevitably varied in the process of welding (assembly process). It leads to waste of time, space and human efforts, worry of safety accidents with the characteristic of the work to be performed on a high place, and non-efficiency and non-economy by using such supplementary equipments as crane. This paper, to remove the needless preassembly process by pre-estimating welding deformation produced under construction of large steel structures, devises a method modeling welded part for applying the equivalence load method and examines the effects of welding sequence and self weight on welding deformation by the method.

• Journal of the Korean Society for Library and Information Science
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• v.52 no.1
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• pp.313-340
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• 2018

The purpose of this study was to design a PCSI model that can be applicable to measurement of library user satisfactions, which can be used in evaluating organizational performance. The National Assembly Library (NAL) was selected as a case to design a PCSI-based model and to test the model by conducting a self-administered survey of 341 internal and external library users. The model was validated to have a satisfactory model fit. Fitting the model, the study confirms that the service qualities of the NAL affect user satisfactions, which in turn affects organizational performances. The PCSI score of the library was 80.4, which can be used as a useful index that can compare the library's performance with other organizations in the similar public domain. Major contributions of this study are two-fold: the PCSI-based model proposed in this study provides a theoretical basis that assesses organizational performance of libraries via user satisfaction; and libraries can utilize the model as a management tool to assess the organizational performance from the user perspective.

• Journal of Advanced Navigation Technology
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• v.27 no.1
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• pp.102-110
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• 2023

The MATS(Missile Assembly Test Set) is manufactured and used to check the function of the missile during the period of development for the guided missile system, and the requirements for power and communication are managed for equipment production. The MATS developer implements software according to the proposed communication standard to guarantee the reliability of the data that communicates with the guided missile. The test bed is built and self-performance evaluation is performed after implementation. And the verification process is performed using the standard equipment. The characteristics of periodic delay for data transmission must be reflected when building a test bed. This paper describes a test bed construction method for data processing with periodic delay. Also This paper compares and evaluates the performance by changing the previously designed algorithm.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.17 no.6
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• pp.255-261
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• 2016

$CaCO_3$ was applied in various industries including rubber, plastics, paint, paper, food additives, and acid neutralizer, etc., owing to its excellent physical and chemical characteristics as well as various appearances of crystals and many reserves. In particular, research on controlling the structure and shape of $CaCO_3$ has attracted considerable attention recently, because the whiteness and physical characteristics of $CaCO_3$ depend on the size and shapes of the particles. In this study, $CaCO_3$ was synthesized using $CaCl_2$ and $(NH4)_2CO_3$, which has multi-shapes and structures, using a self-assembly method with a hydrothermal method. The structure and morphology of the $CaCO_3$ could be controlled by adjusting the pH and precursor concentration. In particular, the pH adjustment appeared to be a critical factor for the morphology and crystal form. In addition, the calcite and cubic shape were obtained at pH 7, while the mixed calcite, aragonite structure, and rod shapes appeared at pH 7 and over. Through an analysis of the particle formation process, the formation of the calcium carbonate particles was confirmed. The physicochemical properties of the synthesized $CaCO_3$ were analyzed by SEM, XRD, EDS, FTIR, and TG/DTA.

• Applied Chemistry for Engineering
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• v.28 no.4
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• pp.404-409
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• 2017

Natural polymer chitosan has been widely applied to medical fields due to its biochemical activities such as anticancer, antibacterial and lowering cholesterol in addition to biocompatibility and biodegradability. Currently, researches are being actively conducted to develop various drug-encapsulated chitosan nanoparticles for curing different diseases by applying chitosan to a drug delivery system. The free amine ($-NH_2$) group present in chitosan can bind to various hydrophobic groups by physical and chemical modification and the chitosan with hydrophobic groups can form shell-core nanoparticles by self-assembly when dispersed in water. In addition, an insoluble drug can increase the solubility against water when it was encapsulated in the core of chitosan nanoparticles. Also, the therapy effect can be maximized by minimizing side effects of drugs such as proteins, anticancer drugs and vaccines when they were encapsulated in the core of chitosan nanoparticles. Moreover, it is possible to control the particle size and release rate according to the hydrophobic group introduced to chitosan, so that it can be applied to a wide range of medical fields. The purpose of this review is to discuss the preparation and property of chitosan nanoparticles modified with various hydrophobic groups, and the application to drug delivery systems according to their property.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.19 no.6
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• pp.305-310
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• 2009

$TiO_2$ thin films consisting of positively charged poly (diallyldimethylammonium chloride) (PDDA) and negatively charged titanium (IV) bis (ammonium lactato) dihydroxide (TALH) were successfully fabricated on a poly (methyl methacrylate) (PMMA) by layer-by-layer (LBL) self-assembly method. By the measurement of quartz crystal microbalance (QCM), it was found that as the solution pH of TALH decreased, the deposition volume of TALH increased and the thickness of (PDDA/TALH) thin film coated on the surface of PMMA particles increased. The PMMA particles coated with the coating sequence of (PDDA/TALH)n showed the variation of color changes as a function of the number of bilayer. The number of bilayer (n) of (PDDA/TALH) thin films was 10 and 20, the values of $a^*$ and $b^*$ decreased from those of PMMA particles without coating films and the color changes was shifted to green and blue direction in the $a^*$, $b^*$ chromaticity diagram. And then, the number of n increased to 30 and 40, the values of $a^*$ and $b^*$ increased and the color changes was shifted to red and yellow direction, respectively. Finally the PMMA particles coated with $(PDDA/TALH)_{50}$ thin film showed a little same value of $a^*$ and $b^*$ with the PMMA particles without (PDDA/TALH) thin film.