• Fibers and Polymers
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• 제3권1호
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• pp.24-30
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• 2002

Wool yams were coated with conducting Polypyrrole by chemical synthesis methods. Polymerization of pyrrole was caned out in the presence of wool yarn at various concentrations of the monomer and dopant anion. The changes in tensile, moisture absorption, and electrical Properties of the yam upon coating with conductive polypyrrole are Presented. Coating the wool yams with conductive Polypyrrole resulted in higher tenacity, higher breaking strain, and lower initial modulus. The changes in tensile properties are attributed to the changes in surface morphology due to the coating and reinforcing effect of conductive Polypyrrole. The thickness of the coating increased with the concentration of p-toluene sulfonic acid, which in turn caused a reduction in the moisture regain of the wool yin. Reducing the synthesis temperature and replacing p-toluenesulfonic acid by anthraquinone sulfonic acid resulted in a large reduction in the resistance of the yam.

• 대한음성학회지:말소리
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• 제44호
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• pp.145-156
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• 2002

This paper describes the reduction of DB without degradation of speech quality in Corpus-based Speech synthesizer of the Korean language. In this paper, it is proposed that the frequency of every unit in reduced DB reflect the frequency of units in the Korean language. So, the target population of every unit is set to be proportional to its frequency in Korean large corpus (780k sentences, 45Mega phones). Secondly, the frequent instances during synthesis should be also maintained in reduced DB. To the last, it is proposed that frequency of every instance be reflected in clustering criteria and used as another important criterion for selection of representative instances. The evaluation result with proposed methods reveals better quality than that using conventional methods.

• 한국분말재료학회지
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• 제13권5호
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• pp.336-339
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• 2006

Magnetic properties of nanostructured materials are affected in complicated manner by their microstructure such as pain size (or particle size), internal strain and crystal structure. Thus, studies on the synthesis of nanostructured materials with controlled microstructure are necessary fur a significant improvement in magnetic properties. In the present work, nanostructured Fe-Co alloy powders with a grain size of 50 nm were successfully fabricated from the powder mixtures of (99.9% purity) $FeCl_2$ and $CoCl_2$ by chemical solution mixing and hydrogen reduction.

• 한국분말재료학회지
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• 제4권4호
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• pp.304-309
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• 1997

The synthesis of W-l5wt%Cu nanocomposite powder by hydrogen reduction of ball milled W-Cu oxide mixture was investigated in terms of powder characteristics such as particle size, mixing homogeneity and micropore structure. It is found that the micropores in the ball milled oxide (2-50 nm in size) act as an effective removal path of water vapor, followed by the formation of dry atmosphere at reaction zone. Such thermodynamic condition enhances the nucleation of W phase but suppresses the growth process, being in favor of the formation of W nanoparticles (about 21 nm in size). In addition, the superior mixing homogeneity of starting oxide mixture turned out to Play a significant role for forming extraordinary chemical homogeneity of W-l5wt%Cu nanocomposite powder.

• 전자공학회논문지A
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• 제33A권10호
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• pp.177-185
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• 1996

This paper describes several algorithms for technolgoy mapping of logic functions into interesting and popular FPGAs that use look-up table memories. In order to improved the technology mapping for FPGA, some existing multi-level logic synthesis, decomposition reduction and packing techniques are analyzed and compared. And then new algorithms such as merging fanin, unified reduction and multiple disjoint decomposition which are used for combinational logic design, are proposed. The cost function is used to minimize the number of CLBs and edges of the network. The cost is a linear combination of each weight that is given by user. Finally we compare our new algorithm with previous logic design technique. In an experimental comparison our algorithm requires 10% fewer CLB and nets than SIS-pga.

• Journal of Electrochemical Science and Technology
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• 제7권1호
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• pp.13-26
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• 2016

Nanoparticles (NPs), which have been investigated intensively as electrocatalysts, are usually synthesized by chemical methods that allow precise size and shape control. However, it is difficult to control the components and compositions of alloy NPs. On the other hand, the conventional physical method, sputtering with solid substrates, allows for facile composition control but size control is difficult. Recently, “liquid medium sputtering” has been suggested as an alternative method that is capable of combining the advantages of the chemical and conventional physical methods. In this review, we will discuss NP synthesis via the liquid medium sputtering technique using ionic liquid and low-volatile polymer media. In addition, potential applications of the technique, including the generation of oxygen reduction reaction electrocatalysts, will be discussed.

• 대한기계학회논문집A
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• 제25권3호
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• pp.495-501
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• 2001

In this paper, a new technique which models the joints characteristics through reduction of DOFs of structures with joints using component mode synthesis (CMS) method is proposed. Bolt joints are modeled by mass-spring systems. Also generalized mass and stiffness matrices for this models are introduced. Because bolt joints have influence on eigenvalues of structures, exact eigenvalues from modal test are used. The results show that the behaviors of structures with bolt joints depend to a large extent on the translational DOFs and not on rotational DOFs of mass and stiffness matrices of bolts. Furthermore it is confirmed that lumped mass-spring systems as models of bolt joints are effective models considering the facts that joint characteristics converged to constant values in some iterations and eignevalues from proposed method are in good agreement with ones from modal test.

• 약학회지
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• 제35권4호
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• pp.314-318
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• 1991

A convenient method for the synthesis of indoprofen, which is a potent antiinflammatory agent, w described. Ethyl $\alpha$-(4-aminophenyl)propionate was prepared by nitration of ethyl $\alpha$-phenylpropionate, followed by reduction. Ethyl $\alpha$-[4-(1, 3-dioxo-2-iso-indolinyl)phenyl]propionate was obtained from condensation reaction of phthatic anhydride and ethyl $\alpha$-(4-aminophenyl)propionate. Indoprofen was prepared by reduction of ethyl $\alpha$-[3-(1, 3-dioxo-2-iso-indolinyl)phenyl]propionate with zinc dust-acetic acid, followed by hydrolysis of the resultant ethyl $\alpha$-[4-(1-oxo-2-iso-indolinyl)pheriyl]propionate.

• 약학회지
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• 제36권1호
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• pp.12-16
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• 1992

A new method for the synthesis of alminoprofen, which is a non-steroidal antiinflammatory agent, was described. Ethyl 2-phenyl-propionate(4) was prepared by Friedel-Crafts reaction of benzene with ethyl ${\alpha}-chloro-{\alpha}(methylthio)acetate(1)$, followed by methylation and desulfurization of the resultant ethyl 2-(methylthio)phenylacetate(2). Ethyl 2-(p-aminophenyl)propionate(6) was obtained by nitration of (4) and successive reduction of ethyl 2-(p-nitrophenyl)propionate(5). Alminoprofen was synthesized by reaction of (6) with methallyl chloride, followed by hydrolysis of the resultant ethyl 2-(p-methylallylaminophenyl)propionate (7).

• 한국세라믹학회지
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• 제22권5호
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• pp.35-42
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• 1985

$eta$-Sialon powders were prepared by reduction-nitridation from mixture of Wando pyrophyllite and graphite as a reducing agent at 135$0^{\circ}C$ in 80% $N_2$-20% $H_2$ atmosphere. As the reaction products $Si_2ON_2$, $\beta$-$Si_3N_4$ a--$Si_3N_4$ and $\beta$-SiC were observed. Additive agents of MgO, CaO, $Y_2O_3$ were used for promoting the reduction and nitridiation aeaction. The present study was conducted to investigate the effects of silica-carbon ratio ($SiO_2$/C=weight ratio), raction time gas flow rate pellet size and powder packing on synthesis of $\beta$-Sialon from Wando pyropyllite.