• Journal of the Korean Chemical Society
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• v.36 no.1
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• pp.137-146
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• 1992

The adsorption properties of CO on the cation exchanged natural zeolite, $K_{111}$ and cation effects upon the CO adsorption were studied. $Na^+-,\;Cu^{2+}-\;and\;Ba^{2+}-\;K_{111}$ exhibited relatively good CO adsorption capacities and $Ba^{2+}- K_{111}$ treated by 0.4 N-$BaCl_2$ solution proved itself as the best adsorbent and superior to the synthetic zeolite 4A and 5A. The observed adsorption tendency due to the cations were in the order of $Ba^{2+}>Cu^{2+}>Na^+>K^+>Mg^{2+}>Ca^{2+}$. The cation exchanged number per unit cell as well as the kind of cation which forms bond with CO molecules in different intensities and other mineral factors such as pore size indicated to be important factors to the CO adsorption properties. The CNDO/2 calculations were performed to compare the adsorption tendencies and CO interaction energy of cations in $K_{111}$.

• Journal of the Korean Applied Science and Technology
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• v.9 no.1
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• pp.63-71
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• 1992

Four novel amphoteric surfactants of N-alkoxyethylcarboxybetaine series were synthesized via Schotten-Baurnman reaction between four alkyl chlorides contaning 10, 12, 14 and 16 carbon atoms in their N-alkyl group and dimethylaminoethanol to give the intermediate products, alkoxyethyldimethylamine, Quaternization of these intermediates was permitted to form 2-(alkoxyethyldimethylarnmonio) acetates, whose structures were identified by elemental analysis. IR spectrophotometry and $^1$Hnmr spectrometry. The yield of the final products was shown in the range of $74{\sim}77%$ based on the yield of the intermediate products, Surface tension of the aqueous solution of the final products was measured. and the critical micelle concentrations(cmc) were shown in the range of $2.82{\times}10^{-3}{\sim}2.67{\times}10^{-6}$mol/l, and the surface thension at erne was 35${\sim}$43dyne/cm. Cmc was lowered gradually by the increase of carbon numbers in N-alkyl ether containing group. The isoelectric point was shown in the range of 4.08${\sim}$6.03. It showed a tendency to lean toward the acidic site and its range was broadened as increase of the hydrophobic group length. A linear relationship between log erne and the number of carbon atoms(N) in the hydrophobic alkyl chain was shown in the relative equation of log cmc=2.49-0.50N.

• ETRI Journal
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• v.39 no.6
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• pp.866-873
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• 2017

We propose a multilayered-substrate-based power semiconductor discrete device package for a low switching loss and high heat dissipation. To verify the proposed package, cost-effective, low-temperature co-fired ceramic, multilayered substrates are used. A bare die is attached to an embedded cavity of the multilayered substrate. Because the height of the pad on the top plane of the die and the signal line on the substrate are the same, the length of the bond wires can be shortened. A large number of thermal vias with a high thermal conductivity are embedded in the multilayered substrate to increase the heat dissipation rate of the package. The packaged silicon carbide Schottky barrier diode satisfies the reliability testing of a high-temperature storage life and temperature humidity bias. At $175^{\circ}C$, the forward current is 7 A at a forward voltage of 1.13 V, and the reverse leakage current is below 100 lA up to a reverse voltage of 980 V. The measured maximum reverse current ($I_{RM}$), reverse recovery time ($T_{rr}$), and reverse recovery charge ($Q_{rr}$) are 2.4 A, 16.6 ns, and 19.92 nC, respectively, at a reverse voltage of 300 V and di/dt equal to $300A/{\mu}s$.

• Bulletin of the Korean Chemical Society
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• v.32 no.1
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• pp.286-290
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• 2011

Ginsenoside Rg3 was reported to have important biological activities. We demonstrate conjugation and quantification procedures of ginsenoside Rg3 to gold nanoparticles for future biological and medical applications. Ginsenoside Rg3 was conjugated to spherical gold nanoparticles using a bifunctional heptaethylene glycol linker. The sulfhydryl group of heptaethylene glycol was adsorbed onto gold nanoparticles, and carboxylic acid end of heptaethylene glycol was bonded through a hydroxyl group of Rg3 via ester bond formation. The conjugation of Rg3 was characterized with various spectroscopic techniques, high resolution-transmission electron microscopy, and using Rg3 monoclonal antibody. The Rg3- functionalized gold nanoparticles were $4.7{\pm}1.0$ nm in diameter with a surface charge of -4.12 mV. The total number of Rg3 molecules conjugated to a 3.6 mL solution of gold nanoparticle was determined to be $9.5{\times}10^{14}$ corresponding to ~6 molecules of Rg3/gold nanoparticle. These results suggest that ginsenoside Rg3 is successfully conjugated to gold nanoparticles via heptaethylene glycol linker. The quantification was performed by using Rg3 monoclonal antibody without interference of gold's intrinsic color.

• Bulletin of the Korean Chemical Society
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• v.31 no.10
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• pp.2761-2770
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• 2010

In this study, we have developed QSAR models for a series of 38 piperidine-4-carboxamide CCR5 antagonists using CoMFA, CoMSIA and HQSAR methods. Developed models showed good statistics in terms of $q^2$ and $r^2$ values. Best predictions obtained with standard CoMFA model ($r^2$ = 0.888, $q^2$ = 0.651) and combined CoMSIA model ($r^2$ = 0.892, $q^2$ = 0.665) with electrostatics and H-bond acceptor parameter. The validity of developed models was assessed by test set of 9 compounds, which showed good predictive correlation coefficient for CoMFA (0.804) and CoMSIA (0.844). Bootstrapped analysis showed statistically significant and robust CoMFA (0.968) and CoMSIA (0.936) models. Best HQSAR model was obtained with a $q^2$ of 0.662 and $r^2$ of 0.936 using atom, connection, hydrogen, donor and acceptor as parameters and fragment size (7-10) with optimum number of 6 components. Predictive power of developed HQSAR model was proved by test set and it was found to be 0.728.

• Journal of the Korean Ceramic Society
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• v.38 no.11
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• pp.1030-1036
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• 2001

Hydroxyapatite[COL] nanocomposite was prepared through coprecipitation process. The chemical bond formation between HAP and COL was confirmed by diffusive reflectance FT-IR and TEM observation. Higher concentration of COL in the preparation induced tiny nanocrystalline composite particles, but lower concentration of COL contributed to form the well developed HAP particles. From TEM observation and ED(Electron Diffraction) pattern the embedded HAP nanoparticles were oriented along the c-axis of COL fiber. In an aqueous system of constant [Ca$\^$2+/] and [PO$_4$$\^$3-/], quantity of soluble COL matrix was doing an important role of controlling the heterogeneous nucleation site for the formation of HAP nanocrystals. Higher concentration of COL will provide more nucleation sites for Ca$\^$2+/ and so the concentration of calcium ions for the total number of active nucleation sites will be getting relatively dilute.

• Transactions of the Korean hydrogen and new energy society
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• v.23 no.3
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• pp.199-206
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• 2012

HC-SCR was conducted over Co-Pt/ZSM5 catalyst coated over 200 cpsi cordierite in the condition of atomspheric pressure and $200^{\circ}C-500^{\circ}C$. Weight ratio of Co/Pt determined from EDX analysis was 8/2, which was almost equal to the weight ratio at preparation step. XPS showed that nitrates within cobalt precursor and chlorine withn Pt precursor were removed. TEM result demonstrated that crystallite size of cobalt and Pt was under 5nm. Among these tested hydrocarbon reductants, isobutane ($i-C_4H_{10}$) showed the highest de-$NO_x$ yield of 80% under the condition of the mole ratio of reductant/NOx=1.0 at $180^{\circ}C$. De-$NO_x$ yield from HC-SCR was increased as the carbon number of hydrocarbon reductant was increased. The decrease of bonding energy between C and H of HC reductant played a role to increase of de-$NO_x$ yield, which indicated that the dissociation step of C-H bond of hydrocarbon molecule might be the rate determining step of HC-SCR. The increase of oxygen concentration in the feed resulted in the decrease of de-$NO_x$ yield but the increase of CO and $N_2O$ yield.

• Genomics & Informatics
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• v.9 no.2
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• pp.69-73
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• 2011

The use of genomic information in genomic selection programs for dairy and beef cattle breeds has become a reality in recent years. In this investigation, we analyzed single-nucleotide polymorphisms (SNPs) for Hanwoo (n=50) and Holstein (n=50) breeds using the Illumina Bovine SNP50 BeadChip to facilitate genomic selection and utilization of the Hanwoo breed in Korea. Analysis of the entire genomes showed different spectra of SNP frequencies for Hanwoo and Holstein cattle. The study revealed a highly significant (p<0.001) difference between Hanwoo and Holstein cattle in minor allele frequency (MAF). The average MAFs were $0.19{\pm}0.16$ and $0.22{\pm}0.16$ for Hanwoo and Holstein, respectively. From the total of 52,337 SNPs that were successfully identified, about 72% and 79% were polymorphic in Hanwoos and Holsteins, respectively. Polymorphic and fixed SNPs were not distributed uniformly across the chromosomes within breeds or between the two breeds. The number of fixed SNPs on all chromosomes was higher in Hanwoo cattle, reflecting the genetic uniqueness of the Hanwoo breed. In general, the rate of polymorphisms detected in these two breeds suggests that the SNPs can be used for different applications, such as whole-genome association and comparative genetic studies, and are a helpful tool in developing breed identification genetic markers.

• Journal of Digital Convergence
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• v.12 no.10
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• pp.243-252
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• 2014

Many researches about the effect on politics, economics and Sociocultural phenomenon using the social media are in progress. Authors utilized NAVER Trend most famous web browsing service in korea, NAVER Blog social media, NAVER Cafe service and Open Data(API) and also used temperature, humidity index data of Korea Meteorological Administration. This study analyzed a change of the public's emotion in korea using Cluster analysis of vocabulary of taste among its of feelings and senses. K-means clustering was followed by decision of the number of groups which was used Chi-square goodness of fit test and ward analysis. Eight groups was made and it represented sensitive vocabulary. By Discriminant analysis, eight groups decided by Cluster analysis has 98.9% accuracy. The change of the public's emotion has capability to predict people's activity so they can share sensibility and a bond of sympathy developed between them.

• Journal of the Korea institute for structural maintenance and inspection
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• v.16 no.1
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• pp.110-119
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• 2012

Fiber reinforced polymer (FRP) reinforcing rebar with non-corrosive property is suggested as an alternative replacement to steel reinforcing rebar due to its enhanced durability and non-corrosive characteristics. Currently, a limited number of glass fiber reinforced polymer rebar (GFRP) are sold commercially due to their high cost, relatively low performances, and brittle failure characteristics. Therefore, the performance enhancements and cost reduction of GFRP rebar are needed to increase its applications in construction fields. The intent of this study is to develop high performance GFRP rebar by improving its tensile and shear properties. Also, in order to reduce manufacturing costs, factors such as material composition and manufacturing process were evaluated to improve manufacturing efficiency. Finally a GFRP rebar with enhanced material properties and less expensive than the GFRP rebar currently sold in the market was manufactured and evaluated for its application possibility in construction fields.