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        검색결과 636

        181.
        2015.10 KCI 등재 구독 인증기관 무료, 개인회원 유료
        생약재 5종(상황버섯, 황금, 단삼, 뽕잎 및 작약)의 물 추출물을 동량으로 혼합한 조성물(MHE-1)과 동일한 추출 수율이 되도록 생약재를 혼합한 후 물 추출한 조성물(MHE-2)의 항산화 및 항염증 활성을 비교 분석하였다. 조성물의 총 페놀 및 플라보노이드 함량은 MHE-2에서 더 많았다. DPPH, ABTS 및 superoxide anion 라디칼 소거활성, Fe+2 킬레이팅 활성, 환원력 및 xanthine oxidase 저해활성 등의 항산화 활성은 MHE-2가 더 우수하였다. 항염증 활성은 LPS에 의한 염증 유발군에 비해 조성물 처리 구에서 유의적으로 NO 생성을 억제하였으며, 100μg/mL 농도로 처리 시 PGE2와 cytokine인 TNF-α, IL-2 및 IL-6의 생성도 유의적으로 감소시켰으나 두 조성물간에 차이는 적었다. 이상의 결과를 볼 때 여러 종류의 생약재를 혼합한 조성물의 생리활성은 원재료를 혼합하여 추출하는 것이 추출물의 생리활 성 증대에 효과적인 것으로 판단된다.
        4,600원
        182.
        2015.10 KCI 등재 SCOPUS 구독 인증기관 무료, 개인회원 유료
        GNPs have several excellent mechanical properties including high strength, a good young’s modulus, thermal conductivity, corrosion resistance, electronic shielding, etc. In this study, CF/GNP/Epoxy composites were manufactured using GNP weight ratios of 0.15 wt%, 0.3 wt%, 0.5 wt%, 0.7 wt% and 1 wt%. The composites were manufactured with a mechanical method (3-roll-mill). Tensile, impact and wear tests were performed according to ASTM standards D3039, D256 and D3181, respectively. The results show that the CF/GNP0.3wt%/Epoxy composites have good mechanical properties, e.g., tensile strength and impact and wear resistance. In this study, both carbon fabric and GNPs were used as reinforcements in the composites. The mechanical properties increased and weight loss decreased as the GNP content in the resin films was increased.
        4,000원
        184.
        2015.09 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Carbon composites for flexible fiber heating element were examined to improve the electrical conductivity in this study. Carbon composites using carbon black, denka black, super-c, super-p with/without CNF or dispersant such as BCS03 and Sikament-nn were prepared. Carbon composite slurry was coated on plane film and yarns(cotton, polyester) and the performances of prepared heating materials were investigated by checking electrical surface resistance, adhesion strength. The plane heating element using carbon black under natural drying condition(25℃) had better physical properties such as surface resistance(185.3 Ohm/sq) and adhesion strength(above 90%) than those of other carbon composite heating elements. From these results, polyester heating element coated by carbon black showed better electrical line resistance(33.2 kOhm/cm) than cotton heating element. Then, it was found that polyester heating element coated by carbon black with CNF(3 wt%) and BCS03(1 wt%) appeared best properties(0.604 kOhm/cm).
        4,000원
        185.
        2015.09 KCI 등재 구독 인증기관 무료, 개인회원 유료
        The repair of manhole raise has been caused much construction times and disruption of traffic flow, serious environmental pollution from crushed construction wastes, and budget waste due to the repeated repair construction works. In order to overcome such problems, we have developed the new manhole repairing composite structures by using a glass fiber-reinforced polymer (GFRP) pipe, which can raise manhole to the regular height of the overlayed road pavement with rapid construction and minimum traffic jams. This environmental-friendly technology is method completed by the methyl methacrylate monomer (MMA) double wide flanged GFRP pipe composite structures in order to raise manhole to the regular height. In this paper, two kinds of the compressive strength tests of MMA mortar composites were conducted and evaluated by a general compressive strength test, and compressive strength test after freezing-thawing resistance test. It was found that this MMA mortar composites will be used for the application of the double wide flanged GFRP pipe composite structures.
        4,000원
        187.
        2015.08 KCI 등재 SCOPUS 구독 인증기관 무료, 개인회원 유료
        This paper investigates the dependency of the critical content for electrical conductivity of carbon powder-filled polymer matrix composites with different matrixes as a function of the carbon powder content (volume fraction) to find the break point of the relationships between the carbon powder content and the electrical conductivity. The electrical conductivity jumps by as much as ten orders of magnitude at the break point. The critical carbon powder content corresponding to the break point in electrical conductivity varies according to the matrix species and tends to increase with an increase in the surface tension of the matrix. In order to explain the dependency of the critical carbon content on the matrix species, a simple equation (Vc* = [1 + 3(γc1/2 − γm1/2)2/(ΔqcR]−1) was derived under some assumptions, the most important of which was that when the interfacial excess energy introduced by particles of carbon powder into the matrix reaches a universal value (Δqc), the particles of carbon powder begin to coagulate so as to avoid any further increase in the energy and to form networks that facilitate electrical conduction. The equation well explains the dependency through surface tension, surface tensions between the particles of carbon powder.
        4,000원
        188.
        2015.06 KCI 등재 구독 인증기관 무료, 개인회원 유료
        The microstructures and cyclic voltammograms of Al-Si/C nano-composites were investigated as the anode of lithium ion batteries. Al-Si nanoparticles were prepared by the arc-discharge method. Al-Si/C nanoparticles were obtained by coated Al-Si nanoparticles with the precursor of glucose (C6H12O6) as carbon source. It was indicated that the post carbon coating treatment can reduce Al2O3 film on Al-Si particles, and new phase Al4C3 formed in the process can activate the inactivated materials of electrode in a certain extent.
        4,000원
        189.
        2015.06 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Flow mark is a sort of surface defect on the composite that can arise during the filling stage of the injection molding process. The purpose of this study is to clarify a mechanism of the flow mark which appears on the surface of injection molded Polypropylene (PP) through the characterization of the surface structure. The materials used in this report are PP/rubber and PP/talc compounding, which are widely used in automobile part. The flow mark shows two different constitutions, such as a luster part and a cloud part on the surface of the injection molded PP. We have investigated the surface structure of PP/rubber and PP/talc composites by using scanning electron microscope (SEM), energy dispersive x-ray spectroscopy (EDAX) and optical microscopy (OM). As a result, the cloud part contains higher contents of the rubber and talc compare to the luster part.
        4,000원
        190.
        2015.06 KCI 등재 구독 인증기관 무료, 개인회원 유료
        The functional wood plastic composite(WPC) is one of the noted materials for landscape architecture and residential construction. Iron band, embossing and drain holes are improve the strength and skid resistance of the WPC. In this study, we had developed an automatic manufacturing system for the functional WPC that has vertical pattern embossing and drain holes. The system is consist of an automatic vertical pattern embossing device, multi-spindle drilling M/C, sanding device, inspection equipment, and some facilities developed in the previous research. The performance tests on the several functional items of the system and manufactured WPC represented satisfactory values except the skid resistance and absorption thickness expansion rate.
        4,000원
        191.
        2015.06 KCI 등재 SCOPUS 구독 인증기관 무료, 개인회원 유료
        In order to prepare anode materials for high power lithium ion secondary batteries, carbon composites were fabricated with a mixture of petroleum pitch and coke (PC) and a mixture of petroleum pitch, coke, and natural graphite (PCNG). Although natural graphite has a good reversible capacity, it has disadvantages of a sharp decrease in capacity during high rate charging and potential plateaus. This may cause difficulties in perceiving the capacity variations as a function of electrical potential. The coke anodes have advantages without potential plateaus and a high rate capability, but they have a low reversible capacity. With PC anode composites, the petroleum pitch/cokes mixture at 1:4 with heat treatment at 1000 oC (PC14-1000C) showed relatively high electrochemical properties. With PC-NG anode composites, the proper graphite contents were determined at 10~30 wt.%. The composites with a given content of natural graphite and remaining content of various petroleum pitch/cokes mixtures at 1:4~4:1 mass ratios were heated at 800~1200 oC. By increasing the content of petroleum pitch, reversible capacity increased, but a high rate capability decreased. For a given composition of carbonaceous composite, the discharge rate capability improved but the reversible capacity decreased with an increase in heat treatment temperature. The carbonaceous composites fabricated with a mixture of 30 wt.% natural graphite and 70 wt.% petroleum pitch/cokes mixture at 1:4 mass ratio and heat treated at 1000 oC showed relatively high electrochemical properties, of which the reversible capacity, initial efficiency, discharge rate capability (retention of discharge capacity in 10 C/0.2 C), and charge capacity at 5 C were 330 mAh/g, 79 %, 80 %, and 60 mAh/g, respectively.
        4,000원
        192.
        2015.06 KCI 등재 구독 인증기관 무료, 개인회원 유료
        It should be noted that the use of the lathe scrap for making fiber reinforced cementitious composites(FRCCs) raised friendly environmental effect as well as economy because the lathe scrap is a by-product of steel manufactures and is occurred when lathe and milling works of them are conducted to process steel manufactures. Thus, the purpose of this research is to investigate the effect of measurements of lathe scrap on the characteristics of FRCCs. For this purpose, various lathe scraps were collected from processing plants of metal, and then these were processed 10mm, 20mm, and 40mm in lengths for 2mm and 4mm in widths, respectively. FRCCs containing lathe scraps were made according to their widths and lengths, and then characteristics such as the workability, compressive strength, and flexural strength of those were evaluated. As a result, it was observed from the test results that the optimum measurements of the lathe scrap for manufacturing FRCCs was 2mm in width and 40mm in length.
        4,000원
        194.
        2015.04 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Carbon fibers (CFs) have a unique combination of properties which allow them to be widely used as reinforcing materials in advanced polymer composites. The mechanical properties of CF-reinforced polymer composites are governed mainly by the quality of interfacial adhesion between the CFs and the polymer matrix. Surface treatments of CFs are generally carried out to introduce chemical functional groups on the fiber surfaces, which provide the ability to control the surface characteristics of CFs. In this study, we review recent experimental studies concerning various surface treatment methods for CFs. In addition, direct examples of the preparation and properties of CF-reinforced thermosetting composites are discussed.
        4,200원
        195.
        2015.04 KCI 등재 구독 인증기관 무료, 개인회원 유료
        In this study, we have developed an automatic manufacturing system for functional wood plastic composites(WPC) which are one of spotlighting materials for landscape architecture and residential construction material. In addition to the existing facilities, this manufacturing system is consist of an automatic hole manufacturing device, iron band supply and winding device, mold with the iron band insert system, calibration unit, control system, etc. We have performed the performance tests for the system such as the specific gravity, bending strength, screw holding power, percentage of moisture content, formaldehyde, absorption thickness, expansion rate, cold resistance(appearance & bending strength), and shock resistance. As a result, the performance of the prototype system satisfies all the objects of this study.
        4,000원
        196.
        2015.04 KCI 등재 구독 인증기관 무료, 개인회원 유료
        WS2-W-WC embedded carbon nanofiber composites were fabricated by using electrospinning method for use in high-performance supercapacitors. In order to obtain optimum electrochemical properties for supercapacitors, WS2 nanoparticles were used as precursors and the amounts of WS2 precursors were controlled to 4 wt% (sample A) and 8 wt% (sample B). The morphological, structural, and chemical properties of all samples were investigated by means of field emission photoelectron spectroscopy, transmission electron microscopy, X-ray diffraction, and X-ray photoelectron spectroscopy. These results demonstrated that the embedded phases of samples A and B were changed from WS2 to WS2-W-WC through carbothermal reaction during carbonization process. In particular, sample B presented high specific capacitance (~119.7 F/g at 5 mV/s), good high-rate capacitance (~60.5%), and superb cycleability. The enhanced electrochemical properties of sample B were explained by the synergistic effect of the using 1-D structure supports, increase of specific surface area, and improved conductivity from formation of W and WC phases.
        4,000원
        197.
        2015.04 KCI 등재 SCOPUS 구독 인증기관 무료, 개인회원 유료
        Ceramics biomaterials are useful as implant materials in orthopedic surgery. In this study, porous HA(hydroxyapatite)/β-TCP(tricalcium phosphate) composite biomaterials were successfully fabricated using HA/β-TCP powders with 10-30 wt% NH4HCO3 as a space holder(SH) and TiH2 as a foaming agent, and MgO powder as a binder. The HA/β-TCP powders were consolidated by spark plasma sintering(SPS) process at 1000 oC under 20 MPa conditions. The effect of SH content on the pore size and distribution of the HA/β-TCP composite was observed by scanning electron microscopy(SEM) and a microfocus X-ray computer tomography system(SMX-225CT). These microstructure observations revealed that the volume fraction of the pores increased with increasing SH content. The pore size of the HA/β-TCP composites is about 400-500 μm. The relative density of the porous HA/β-TCP composite increased with decreasing SH content. The porous HA/β-TCP composite fabricated with 30%SH exhibited an elastic modulus similar to that of cortical bone; however, the compression strength of this composite is higher than that of cortical bone.
        4,000원