• Information and Communications Magazine
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• v.24 no.7
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• pp.69-78
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• 2007

본고에서는 광대역 무선 멀티미디어 재난통신 기술의 기술개발 동향 및 표준화 동향을 알아본다. 기술 개발동향의 경우는 정보시스템, 센서망, 통신 인프라 측면에서 개발하고 있는 프로젝트 내용을 분석하고 필요한 기술들을 알아본다. 표준의 경우는 MESA, ETSI (EMTEL, TETRA, SES) 등 주요 표준 단체의 표준 추진현황을 살펴보고 내용을 설명한다.

• Magazine of the Korea Concrete Institute
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• v.26 no.1
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• pp.51-55
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• 2014

• Proceedings of the Korean Nuclear Society Conference
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• 2005.05a
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• pp.247-248
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• 2005

• Bulletin of the Korean Chemical Society
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• v.24 no.5
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• pp.671-673
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• 2003

• Proceedings of the Korean Vacuum Society Conference
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• 2007.08a
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• pp.379-379
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• 2007

• Korean Chemical Engineering Research
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• v.54 no.1
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• pp.36-43
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• 2016

Hydrosilylation reactions of 2.4.6.8-tetrahydro-2.4.6.8-tetramethylcyclotetrasiloxane with allyl butyrate catalyzed by Karstedt's, $H_2PtCl_6$ and Pt/C catalyst were studied and 2.4.6.8-tetra (propyl butyrate)-2.4.6.8-tetramethylcyclotetrasiloxane was obtained. The reaction order, activation energies and rate constants were determined. Ringopening polymerization of 2.4.6.8-tetra (propyl butyrate)-2.4.6.8-tetramethylcyclotetrasiloxane in the presence of $CaF_2$, LiF, KF and anhydrous potassium hydroxide in $60-70^{\circ}C$ temperature range was carried out and methylsiloxane oligomers with regular arrangement of propyl butyrate pendant groups were obtained. The synthesized products were studied by FTIR and NMR spectroscopy. The polysiloxanes were characterized by wide-angle X-ray, gel-permeation chromatography and DSC analyses. Via sol-gel processes of oligomers doped with lithium trifluoromethylsulfonate or lithium bis (trifluoromethylsulfonyl)imide, solid polymer electrolyte membranes were obtained. The dependences of ionic conductivity of obtained polyelectrolytes on temperature and salt concentration were investigated, and it was shown that electric conductivity of the polymer electrolyte membranes at room temperature changed in the range $3.5{\times}10^{-4}{\sim}6.4{\times}10^{-7}S/cm$.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.9 no.1
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• pp.34-38
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• 1999

$PbTiO_3$(PT)thin films were prepared by simultaneous of $TiO_2$ and PbO on Si(100) substrate using metaloganic chemical vapor deposition (MOCVD). Titanium tetra-isopropoxide (TTIP) and $Pb(TMHD)_2$were used as source materials. As evaporation temperature and flow rate of TTIP were examined the crystal structure of PT thin films using XRD with setting deposition temperature, flow rate of Pb, and total flow rate of $520^{\circ}C$, 30 sccm, and 750 sccm, respectively. PT thin films could be deposited under 48~$50^{\circ}C$ and 18~22sccm of evaporation temperature and flow rate of TTIP, respectively. It was found that lead, oxygen, and silicon diffused at the iaterface between the film and the substrate.

• The Journal of the Korea institute of electronic communication sciences
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• v.11 no.8
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• pp.729-734
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• 2016

The current domestic railway wireless communication networks transmit and receive data using several communication schemes such as VHF, TRS-ASTRO, and TRS-TETRA depending on the specific region. Recently, LTE scheme has been adopting in railway wireless communication systems to provide various services and increase reliability. It is critical to support the network interoperability between the existing communication schemes and new communication scheme for seamless data transmission. In this paper, we propose two interoperability schemes in railway communications networks, i.e., network oriented scheme and terminal oriented scheme. We consider the operation scenario for each scheme and compare two interoperability schemes. The practical implementation issues are also discussed based on suggested schemes.

• YAKHAK HOEJI
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• v.40 no.2
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• pp.170-176
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• 1996

A chemical examination of the aerial parts of Euphorbia pekinensis $R_{UPRECHT}$. (Euphorbiaceae) has led to the isolation of seven hydrolyzable tannins and ten fl avonoid glycosides. The former ones have been identified as gallic acid, methylgallate, 3-O-galloyl shikimic acid, 1,3,4,6-tetra-O-galloyl-${\beta}-_D$-glucose, 1,2,3,4,6-penta-O-galloyl-${\beta}-_D$-glucose, corilagin, geraniin and the latter ones as isoquercitrin, quercitrin, astragalin, afzelin, prunin, rutin, kaempferol-3-O-rutinoside, quercetin-3-O-(2"-O-galloyl)-${\beta}-_D$-glucoside and quercetin-3-O-(2"-O-galloyl)-${\alpha}-_L$-rhamnoside on the basis of chemical and spectroscopic evidence.

• Journal of Aquaculture
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• v.11 no.3
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• pp.295-301
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• 1998

Since the end of the Pliocene, ancestral strains of Astyanax fasciatus have been accidently washed into different caves at the time of flooding and have lost their eyes and body pigments. Availability of this independently derived cave fish and their ancestral form within a single species provided a unique opportunity for studying the process of molecular evolution of the visual pigment gene. The nucleotide sequence comparisons of an ancestral river fish and two cave fish showed that nucleotide polymorphism of a green-like visual pigment gene between the eyed and blind form of A. fasciatus was much higher than that between the same blind form. Considering the number of nucleotide substitutions per nucleotide site and the direction of the nucleotide substitutions, more nucleotide substituions between the different forms of fish rater than the same one were probably due to more frequent mutations in the eyed river form. Nucleotide substitutions per site at the intron have been ocurred more than three times faster than those at the exon. This result indicates that the functional constraint has affected the green-like visual pigment gene of the blind cave fish although its eye sight is no longer required.