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        검색결과 6

        2.
        2018.06 구독 인증기관 무료, 개인회원 유료
        Russian foreign policy on the Korean peninsula had always been defined by its economic and security priorities, but these priorities changed over the course of history. Division of Koreas, the ongoing nuclear crisis, economic sanctions and information war point to the continuous tensions between at least three regional powers: the United States, Russia and China. Russia in this context attempts to play an important role of a negotiations’ facilitator and behind-the-scene peace broker whose position may be unique in the ongoing talks. Its geographical proximity to Korea (Russian port of Vladivostok is situated in 100 km from the North Korean border), its historical ties to North Korea, but also its current economic ties to South Korea define its diplomatic position in ongoing negotiations. The fundamental goal of Russian policy in the region is the preservation of stability on the Korean peninsula. Russia seeks to find the optimal balance between all parties implicated in negotiations with the end-goal to play the role of a regional power broker and regain the influence it once had in the region.
        3,000원
        3.
        2018.04 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Adsorption is one of the best methods for wastewater purification. The fact that water quality is continuously decreasing requires the development of novel, effective and cost available adsorbents. Herein, a simple procedure for the preparation of a magnetic adsorbent from agricultural waste biomass and ferrofluid has been introduced. Specifically, ferrofluid mixed with wheat straw was directly pyrolyzed either by microwave irradiation (900 W, 30 min) or by conventional heating (550°C, 90 min). Magnetic biochars were characterized by X-ray powder diffraction, Mössbauer spectroscopy, textural analysis and tested as adsorbents of As(V) oxyanion and cationic methylene blue, respectively. Results showed that microwave pyrolysis produced char with high adsorption capacity of As(V) (Qm= 25.6 mg g–1 at pH 4), whereas conventional pyrolysis was not so effective. In comparison to conventional pyrolysis, one-step microwave pyrolysis produced a material with expressive microporosity, having a nine times higher value of specific surface area as well as total pore volume. We assumed that sorption properties are also caused by several iron-bearing composites identified by Mössbauer spectroscopy ([super] paramagnetic Fe2O3, α-Fe, non-stoichiometric Fe3C, γ-Fe2O3, γ-Fe) transformed from nano-maghemite presented in the ferrofluid. Methylene blue was also more easily removed by magnetic biochar prepared by microwaves (Qm=144.9 mg g–1 at pH 10.9) compared to using conventional techniques.
        4,300원
        6.
        2006.04 구독 인증기관·개인회원 무료
        By means of magnetic pulsed compaction and sintering of weakly aggregated alumina based nanopowders the jet forming nozzle samples for the hydroabrasive cutting were fabricated. The ceramics was obtained from pure alumina, as well as from alumina, doped by , MgO and AlMg. It was shown that the samples sintered from AlMg doped powder have the best mechanical properties and structural characteristics: relative density , channel microhardness. - 18-20 GPa, channel surface roughness , average crystallite size .