• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 1998.04a
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• pp.419-425
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• 1998

This paper presents a method of enhancing the accuracy of hybrid modelling that predicts dynamic characteristics of the coupled structure by synthesizing after FE analysis and vibration experimental analysis of the relevant individual substructure. Since most FE models in engineering problems are very large, dynamic analysis with the full FE model is costly. Frequency response function(FRF) synthesis after reducing the FE model can reduce this computational cost but introduce mode truncation error similarly in the case of considering only low-frequency mode after eigensolutions of the complete structure. This paper introduces a FRF of FE model for hybrid FRF synthesis, which is reduced by using IIRS methods and compensated through eigensolutions of the reduced model, and shows the effectiveness of the presented method.

• Journal of Powder Materials
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• v.10 no.5
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• pp.333-336
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• 2003

The purpose of this study is the fabrication of nano-sized Fe-Co alloy powders with soft magnetic properties by the slurry mixing and hydrogen reduction (SMHR) process. $FeCl_2$0 and $CoCl_2$ powders with 99.9% purities were used for synthesizing nanostructured Fe-Co alloy powder. Nano-sized Fe-Co alloy powders were successfully fabricated using SMHR, which was performed at 50$0^{\circ}C$ for 1 h in H$_2$ atmosphere. The fabricated Fe-Co alloy powders showed $\alpha$' phase (ordered body centered cubic) with the average particle size of 45 nm. The SMHR powder exhibited low coercivity force of 32.5 Oe and saturation magnetization of 214 emu/g.

• Journal of the Korean Operations Research and Management Science Society
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• v.1 no.1
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• pp.139-145
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• 1976

To evaluate the composite composed of Shell-Oil Co. itself and its sub-sidiary companies, the account data for 10 years from 1964 to 1973 was analyzed. Before analyzing, the formula needed to it was deduced and by synthesizing the deduced formula, the price earning ratio (R) was computed as the trial and error method. Resultantly the earning power (ic) was less than 5% ie. R=17.03. So this company showed the normal company earnings and allotment from 1964 to 1968. From 1968 to 1970, the allotment was increased but the earnings was decreased. And in spite of the successive increase of the allotment from 1970 to 1973, the company showed that it was the stable and profitable one with stable increase of earnings. In conclusion, this company showed the stable trend of increase in the allotment of earnings and earnings itself.

• Environmental Analysis Health and Toxicology
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• v.6 no.3_4
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• pp.143-148
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• 1991

This study was carried out to develop the low-priced adsorbent by synthesizing the zeolite of high cation exchange capacity with the natural zeolite and to examine the adsorbing ability of this zeolite. The dominant clay minerals were clinoptilolite and mordenite in natural zeolite, while phillipsite in the synthesized zeolite. Adsorption reaction of $NH_4^{+}$on zeolite was reached equilibrium after 2 hrs. The amount of adsorption was increased with increasing the concentration of $NH_4^{+}$or the pH of suspension. The cation exchange capacity of zeolite was slightly decreased below pH 4.0 by acidic treatment. It was estimated that the ability of the synthesized zeolite to remove noxious ions was better than that of the natural zeolite.

• Proceedings of the Korean Powder Metallurgy Institute Conference
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• 2000.11a
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• pp.10-10
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• 2000

Mechanical alloying (MA) is a powder metallurgy processing technique involving cold welding, fracturing, and rewelding of powder particles in a high-energy ball mill. This has now become an established commercial technique in producing oxide dispersion strengthened (ODS) nickel- and iron-based materials. The technique of MA is also capable of synthesizing non-equilibrium phases such as supersaturated solid solutions, metastable crystalline and quasicrystalline intermetallic phases, nanostructures, and amorphous alloys. In this respect, the capabilities of MA are similar to those of another important non-equilibrium processing technique, viz, rapid quenching of metallic melts. however, the science of MA is being investigated only during the past ten years or so. The technique of mechanochemistry, on the other hand, has had a long history and the materials produced this way have found a number of technological applications, e.g., in areas such as hydrogen storage materials, heaters, gas absorber, fertilizers. catalysts, cosmetics, and waste management. The present talk will concentrate on the basic mechanisms of formation of non-equilibrium phases by the technique of MA and these aspects will be compared with those of rapid quenching of metallic melts. Additionally, the variety of technological applications of mechanically alloyed products will be highlighted.

• Journal of the Korean Applied Science and Technology
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• v.26 no.2
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• pp.199-204
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• 2009

Silicone dioxide absorbed polyoxyethylene alkylether sulfate (EU-S133D) surfactant was prepared. Core-shell polymers of inorganic/organic pair, which have both core and shell component, were synthesized by sequential emulsion polymerization using Acrylate as a shell monomer and potassium persulfate (KPS) as an initiator. We found that when Acrylate core prepared by adding 2.0 wt% EU-S133D, silicone dioxide/Acrylate core-shell polymerization was carried out on the surface of silicone dioxide particle without forming the new silicone dioxide particle during acrylate shell polymerization in the inorganic/organic core-shell polymer preparation. The structure of core-shell polymer were investigated by measuring to the thermal decomposition of polymer composite using thermogravimetric analyzer and morphology of latex by scanning electron microscope(SEM).

• Advances in nano research
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• v.5 no.3
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• pp.253-260
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• 2017

We report a simple eco-friendly process for the synthesis of gold nanoparticles (AuNPs) using aqueous extract from Coffea Arabica fruit. The formation of AuNPs was confirmed using absorption spectroscopy and scanning electron microscopy images. FT-IR analysis demonstrates the major functional groups present in Coffee Arabica fruit extract before and after synthesizing AuNPs. The Face Center Cubic (FCC) polycrystalline nature of these particles was identified by X-Ray diffraction (XRD) analysis. Taking into account the contribution of the biomass surrounding the AuNPs, dynamic light scattering (DLS) results revealed an average particle size of ~59 nm.

• The Journal of the Acoustical Society of Korea
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• v.16 no.3
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• pp.5-12
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• 1997

In this paper, the 3 operator FM synthesis method has been devised on the basis of the analysis of Gayageum sounds. The parameters for the proposed synthesis algorithm has been implemented by C language. It is subjectively and objectively confirmed that the sounds synthesized by C language are very similar to the original sounds. The synthesis algorithm is also implemented by DSP, and the sounds from this experiment are close to the original ones.

• Journal of the Korean Applied Science and Technology
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• v.27 no.1
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• pp.56-60
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• 2010

Titanium dioxide particles are used as photocatalysts, sensors, adsorbents and catalyst. Core-shell polymers of inorganic/organic pair, which have both core and shell component, were synthesized by sequential emulsion polymerization using Acrylate as a shell monomer and potassium persulfate (KPS) as an initiator. We found that when Acrylate core prepared by adding 0.5~2.0 wt% EU-S133D, Titanium dioxide / Acrylate core-shell polymerization was carried out on the surface of Titanium dioxide particle without forming the new Titanium dioxide particle during acrylate shell polymerized in the inorganic/organic core-shell polymer preparation. The structure of core-shell polymer were investigated by measuring to the thermal decomposition of polymer composite using thermogravimetric analyzer(TGA) and morphology of latex by scanning electron microscope(SEM).

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2000.10a
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• pp.263-266
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• 2000

In this paper, we formed a transmitter and receiver by using two identical Chua's circuits and then formed wireless transmission line from the channel which was between those two circuits. We proposed a secure communication method in which the desired information signal was synthesized with the chaos signal created in a Chua's circuit and sent to the transmitter through channel. Then the signal was demodulated receiver of Chua's circuit. The method we used to accomplish the sun communication was synthesizing the desired information with the chaos circuit by parallel connection in a wireless transmission line. After transmitting the synthesized signal to the wireless transmission line, we confirmed the actuality of the secure communication by separating the information signal and the chaos signal in the receiver. In order to confirm the security, we compared the wiretapped signal and the recovery signal under the assumption that the wiretapping had taken place. In order to separate the two signals, we transformed the information signal to a current source in the transmitter and detected the current in the receiver.