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        검색결과 4,563

        2201.
        2009.06 KCI 등재 구독 인증기관 무료, 개인회원 유료
        The purpose of this paper is to give information on e-CPC implementation in the manufacturing industry by studying and analyzing a small and medium sized manufacturing company. After analyzing Various factors on J’s e-CPC implementation such as environmen
        4,000원
        2202.
        2009.06 KCI 등재 구독 인증기관 무료, 개인회원 유료
        This paper presents a novel single-step method to prepare the Ag nanometallic particle dispersed fluid (nanofluid) by electrical explosion of wire in liquid, deionized water (DI water). X-ray diffraction (XRD), field emission scanning electron microscope (FE-SEM) and transmission electron microscope (TEM) were used to investigate the characteristics of the Ag nanofluids. Zeta potential was also used to measure the dispersion properties of the as-prepared Ag nanofluid. Pure Ag phase was detected in the nanofluids using water. FE-SEM analysis shows that the size of the particles formed in DI water was about 88 nm and Zeta potential value was about -43.68 without any physical and chemical treatments. Thermal conductivity of the as-prepared Ag particle dispersed nanofluid shows much higher value than that of pure DI water.
        4,000원
        2203.
        2009.06 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Eu red phosphor was prepared by microwave synthesis. The crystal phase, particle morphology, and luminescent properties were characterized by XRD, SEM, and spectrofluorometer, respectively. The prepared :Eu particles had good crystallinity and strong red emission under ultravioletet excitation. The crystallite size increased with calcination temperature and satuarated at . The primary particle size initially formed was varied from 30 to 450 nm with microwave-irradiation (MI) time. It was found that the emission intensity of :Eu phosphor strongly depends on the MI time. In terms of the emission intensity, it was recommended that the MI time should be less than 15 min. The emission intensity of :Eu phosphor prepared by microwave syntehsis strongly depended on the crystallite size of which an optimal size range was 50-60 nm
        4,000원
        2204.
        2009.06 KCI 등재 구독 인증기관 무료, 개인회원 유료
        A visible-light photoactive photocatalyst was synthesized successfully by means of cogrinding of anatase- in ambient, followed by heat-treatment at in air environment. In general, it is well known that the grinding-operation induces phase transformation of a- to rutile . This study investigates the influence of the amount of gas on the phase transformation rate of a- and enhancement of visible-light photocatalytic activity, and also examines the relation between the photocatalytic activity and the period of grinding time. The phase transformation rate of a- to rutile is retarded with the amount of NH3 injected. And the visible-light photocatalytic activity of samples, was more closely related to the period of grinding time than amount injected, which means that the doping amount of nitrogen into more effective to mechanical energy than amount injected. XRD, XPS, FT-IR, UV-vis, Specific surface area (SSA), NOx decomposition techniques are employed to verify above results more clearly.
        4,000원
        2205.
        2009.06 KCI 등재 구독 인증기관 무료, 개인회원 유료
        The calcination and hydrogen-reduction behavior of Fe- and Ni-nitrate have been investigated. /NiO composite powders were prepared by chemical solution mixing of Fe- and Ni-nitrate and calcination at for 2 h. The calcined powders were hydrogen-reduced at for 30 min. The calcination and hydrogen-reduction behavior of Fe- and Ni-nitrate were analyzed by TG in air and hydrogen atmosphere, respectively. TG and XRD analysis for hydrogen-reduced powders revealed that the /NiO phase transformed to phase at the temperature of . The activation energy for the hydrogen reduction, evaluated by Kissinger method, was measured as 83.0 kJ/mol.
        4,000원
        2218.
        2009.05 KCI 등재 SCOPUS 구독 인증기관 무료, 개인회원 유료
        Mn-substituted BiFeO3(BFO) thin films were prepared by r.f. magnetron sputtering under an Ar/O2mixture of various deposition pressures at room temperature. The effects of the deposition pressure andannealing temperature on the crystallization and electrical properties of BFO films were investigated. X-raydiffraction patterns revealed that BFO films were crystallized for films annealed above 500oC. BFO filmsannealed at 550oC for 5 min in N2 atmosphere exhibited the crystallized perovskite phase. The (Fe+Mn)/Biratio decreased with an increase in the deposition pressure due to the difference of sputtering yield. The grainsize and surface roughness of films increased with an increase in the deposition pressure. The dielectricconstant of BFO films prepared at various conditions shows 127~187at 1kHz. The leakage current densityof BFO films annealed at 500oC was approximately two orders of magnitude lower than that of 550oC. Theleakage current density of the BFO films deposited at 10~30m Torr was about 5×10-6~3×10-2A/cm2 at 100kV/cm. Due to the high leakage current, saturated P-E curves were not obtained in BFO films. BFO film annealedat 500oC exhibited remnant polarization(2Pr) of 26.4µC/cm2 at 470kV/cm.
        4,000원
        2219.
        2009.05 KCI 등재 SCOPUS 구독 인증기관 무료, 개인회원 유료
        The electrocatalytic behavior of the PtCo catalyst supported on the multi-walled carbon nanotubes (MWNTs) has been evaluated and compared with commercial Pt/C catalyst in a polymer electrolyte membrane fuel cell(PEMFC). A PtCo/MWNTs electrocatalyst with a Pt:Co atomic ratio of 79:21 was synthesized and applied to a cathode of PEMFC. The structure and morphology of the synthesized PtCo/MWNTs electrocatalysts were characterized by X-ray diffraction and transmission electron microscopy. As a result of the X-ray studies, the crystal structure of a PtCo particle was determined to be a face-centered cubic(FCC) that was the same as the platinum structure. The particle size of PtCo in PtCo/MWNTs and Pt in Pt/C were 2.0 nm and 2.7 nm, respectively, which were calculated by Scherrer's formula from X-ray diffraction data. As a result we concluded that the specific surface activity of PtCo/MWNTs is superior to Pt/C's activity because of its smaller particle size. From the electrochemical impedance measurement, the membrane electrode assembly(MEA) fabricated with PtCo/MWNTs showed smaller anodic and cathodic activation losses than the MEA with Pt/C, although ohmic loss was the same as Pt/C. Finally, from the evaluation of cyclic voltammetry(CV), the unit cell using PtCo/MWNTs as the cathode electrocatalyst showed slightly higher fuel cell performance than the cell with a commercial Pt/C electrocatalyst.
        4,000원
        2220.
        2009.05 KCI 등재 구독 인증기관 무료, 개인회원 유료
        천연조미소재 개발을 위하여 고압/효소분해 시스템에서 멸치 단백질의 분해 품질특성을 탐색한 결과, 최적 조건은 효소농도 0.6%, 온도 50oC, 처리시간 24시간 및 압력 50 MPa로 확인되었다. 멸치 단백질의 처리방법에 따른 품질특성을 비교한 결과, 최적조건하에서 고압/효소 처리한 멸치 가수분해물의 품질특성이 가열추출물인 대조구에 비하여 2.8배, 2배, 1.4배 증가하여 고압/효소 처리에 의한 단백질 가수분해물 생산은 가열추출법이나 고압반응에 비하여 효율적인 방법으로 나타났다. 효소종류에 따른 분해력은 복합효소로 가수분해한 경우 상업효소에 비하여 큰 증가율을 나타내어 복합효소의 분해력이 상업효소에 비하여 우수하였다. 고압/효소 처리 후의 멸치 가수분해물은 정미성 아미노산으로 알려져 있는 glutamic acid, glycine, arginine 및 alanine 등의 함량이 대조구나 압력 처리구의 유리아미노산 함량에 비하여 증가하였다. 결론적으로 고압/효소분해 처리공정은 멸치 단백질의 효과적 분해와 정미성 아미노산 생산에 효율적인 기술임을 확인하였다.
        4,000원