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        검색결과 1,708

        381.
        2018.12 KCI 등재 SCOPUS 구독 인증기관 무료, 개인회원 유료
        In this study, glass fibers are fabricated via a continuous spinning process using manganese slag, steel slag, and silica stone. To fabricate the glass fibers, raw materials are put into an alumina crucible, melted at 1550℃ for 2 hrs, and then annealed at 600℃ for 2 hrs. We obtain a black colored glass. We identify the non-crystalline nature of the glass using an XRD(x-ray diffractometer) graph. An adaptable temperature for spinning of the bulk marble glass is characterized using a high temperature viscometer. Spinning is carried out using direct melting spinning equipment as a function of the fiberizing temperature in the range of 1109℃ to 1166℃ , while the winder speed is in the range of 100rpm to 250rpm. We investigate the various properties of glass fibers. The average diameters of the glass fibers are measured by optical microscope and FE-SEM. The average diameter of the glass fibers is 73 μm at 100rpm, 65 μm at 150rpm, 55 μm at 200rpm, and 45 μm at 250rpm. The mechanical properties of the fibers are confirmed using a UTM(Universal materials testing machine). The average tensile strength of the glass fibers is 21MPa at 100rpm, 31MPa at 150rpm, 34MPa at 200rpm, and 45MPa at 250rpm.
        4,000원
        382.
        2018.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        The impact of different mixing methods and sintering temperatures on the microstructure and piezoelectric properties of PZNN-PZT ceramics is investigated. To improve the sinterability and piezoelectric properties of these ceramics, the composition of 0.13Pb((Zn0.8Ni0.2)1/3Nb2/3)O3-0.87Pb(Zr0.5Ti0.5)O3 (PZNN-PZT) containing a Pb-based relaxor component is selected. Two methods are used to create the powder for the PZNN-PZT ceramics. The first involves blending all source powders at once, followed by calcination. The second involves the preferential creation of columbite as a precursor, by reacting NiO with Nb2O5 powder. Subsequently, PZNN-PZT powder can be prepared by mixing the columbite powder, PbO, and other components, followed by an additional calcination step. All the PZNNPZT powder samples in this study show a nearly-pure perovskite phase. High-density PZNN-PZT ceramics can be fabricated using powders prepared by a two-step calcination process, with the addition of 0.3 wt% MnO2 at even relatively low sintering temperatures from 800℃ to 1000℃. The grain size of the ceramics at sintering temperatures above 900℃ is increased to approximately 3 μm. The optimized PZNN-PZT piezoelectric ceramics show a piezoelectric constant (d33) of 360 pC/N, an electromechanical coupling factor (kp) of 0.61, and a quality factor (Qm) of 275.
        4,000원
        383.
        2018.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        To abate the problem of odor from restaurants, a hybrid adsorbent consisting of organic and inorganic materials was developed and evaluated using acetaldehyde as a model compound was deveioped and evaluated. Powders of activated carbon, bentonite, and calcium hydroxide were mixed and calcinated to form adsorbent structure. The surface area of the hybrid adsorbent was smaller than that of high-quality activated carbon, but its microscopic image showed that contours and pores were developed on its surface. To determine its adsorption capacity, both batch isotherm and continuous flow column experiments were performed, and these results were compared with those using commercially available activated carbon. The isotherm tests showed that the hybrid adsorbent had a capacity 40 times higher than that of the activated carbon. In addition, the column experiments revealed that breakthrough time of the hybrid adsorbent was 2.5 times longer than that of the activated carbon. These experimental results were fitted to numerical simulations by using a homogeneous surface diffusion model (HSDM); the model estimated that the hybrid adsorbent might be able to remove acetaldehyde at a concentration of 40 ppm for a 5-month period. Since various odor compounds are commonly emitted as a mixture when meat is barbecued, it is necessary to conduct a series of experiments and HSDM simulations under various conditions to obtain design parameters for a full-scale device using the hybrid adsorbent.
        4,000원
        384.
        2018.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        PURPOSES: The objective of this study is to evaluate the properties of eco-friendly waterproofing materials for bridge decks. METHODS: Various waterproofing materials and construction methods that are widely used in Korea were evaluated. Then, the problems in field application were identified. In order to solve these problems, it is necessary to improve constructability and stability. Thus, the properties of heating waterproofing membranes and waterproofing systems using recycling additives were evaluated. In addition, a field test was conducted to ensure the construct-ability and stability. RESULTS AND CONCLUSIONS : Waterproofing materials were developed using waste tires and carbon black the results of the softening point test, tensile adhesion test, and shear adhesion test. A new sheet system, which consists of mesh and vinyl, was also determined from the sheet test. The properties of waterproofing materials were better than those developed under the "A Asphalt Concrete Pavement Construction Guidelines" according to the results of laboratory tests and the report of the authorized testing agency. Finally, the field test showed that the materials met quality standards. In future research, it will be necessary to conduct continuous field tests and follow-up inspections.
        4,200원
        385.
        2018.12 구독 인증기관 무료, 개인회원 유료
        현대사회는 반려동물을 기르는 가정이 증가하고 있다. 인간을 비롯한 반려동물도 일상 생활 속에서 피부질환의 위험에 놓여있고, 이에 따라 피부에 자극을 주지 않는 천연 세정 제품에도 큰 관심이 집중되고 있다. 천연제품이 대중화되어가고 있지만, 편리성과 즉효성을 장점으로 내세우는 일반 세제와 비누보다 천연제품의 이점을 보여주는 정확한 사례가 적다. 이를 알아보기 위해 기존에 사용되었던 세정제 제품을 직접 제작한 천연비누로 교체하였을 때의 피부변화를 실험하였다. 더 정확한 결과 값 측정을 위해 일제히 통제된 환 경에서 지정된 15마리의 실험견들을 선별하고, 유 수분 측정기와 관찰현미경을 이용해 연구를 진행하였고, 천연비누의 교체로 유분, 수분 함량은 증가하였고, 개선된 피부 상태를 확인했다.
        4,000원
        386.
        2018.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        PURPOSES : The objective of this study is to evaluate the performance of combined organic and inorganic hybrid mortar used as repair materials (UM mortar) for concrete road facilities by comparison with cement repair materials (RM mortar). METHODS: In order to produce UM mortar, four different levels of inorganic materials were adopted and the ratio of main resin to hardener was fixed at 1:2. For comparison, RM mortar made with cement repair materials was also produced. Fluidity, strength characteristics, length change, and freezing-thawing resistance of the mortars were measured at the predetermined periods. In addition, the microstructures of the mortars was performed on the 28-day mortar samples to examine the properties of the interfacial transition zone (ITZ). RESULTS : It was observed that the mechanical properties, except for compressive strength, and freezing-thawing resistance of UM mortars were much better than those of RM mortar. Furthermore, showing a densified ITZ properties on the UM mortars from the microstructural observation, the usage of UM mortars exhibited a beneficial effect on the enhancement of mortar properties. CONCLUSIONS: It is concluded that the application of combined organic and inorganic hybrid mortars is a possible option for the repair of deteriorated concrete road facilities.
        4,000원
        388.
        2018.11 구독 인증기관·개인회원 무료
        Three new asymmetric light emitting organic compounds were synthesized with diphenylamine or triphenylamine side groups; 10-(3,5-diphenylphenyl)-N,N-diphenylanthracen-9-amine (MADa), 4-(10-(3,5-diphenylphenyl)anthracen-9-yl)-N,N-diphenylaniline (MATa), and 4-(10-(30,50-diphenylbiphenyl-4-yl) anthracen-9-yl)-N,N-diphenylaniline (TATa). MATa and TATa had a PLmax at 463 nm in the blue region, and MADa had a PLmax at 498 nm. The EL efficiency and color coordinate values (respectively) were 10.3 cd/A and (0.199, 0.152; bluish-green) for the MADa device, 4.67 cd/A and (0.151, 0.177) for the MATa device, and 6.07 cd/A and (0.149, 0.177) for the TATa device. The TATa device had a high external quantum efficiency (EQE) of 6.19%, and its luminance and power efficiencies and life-time were more than twice those of the MADN device.
        389.
        2018.11 구독 인증기관·개인회원 무료
        We synthesized new hole-transporting material, N,N'-diethyl-3,3'-bicarbazyl (E-Cvz-2), 9,9'-diethyl-6-(9-ethyl-carbazol-3-yl)-3,3'-bicarbazole (E-Cvz-3), 6-(9,9'-diethyl-3,3'-bicarbazol-6-yl)-9,9'-diethyl-3,3'-bicarbazole (E-Cvz-4A) and 9-ethyl-6-(9-ethyl-3,9'-bicarbazol-6-yl)-3,9'-bicarbazole (E-Cvz-4B). EL luminance efficiencies of E-Cvz-2, E-Cvz-3, E-Cvz-4A and E-Cvz-4B devices were found to be 4.77, 5.68, 4.27 and 4.64 cd/A, respectively, when synthesized materials are using as a HTL material. The luminance efficiency of E-Cvz-3 is 25% higher than that of NPB, a commercialized HTL material used as a reference in this study.
        390.
        2018.11 구독 인증기관·개인회원 무료
        Water electrolysis is a representative electrochemical process to generate hydrogen gas together with oxygen gas by applying electric power. Perfluorinated sulfonic acid (PFSA) ionomers have been widely used as electrode binder materials, in addition to polymer electrolyte membrane materials for water electrolysis to generate hydrogen and oxygen gases with a high purity simultaneously. PFSA binder materials act as physical supports for inorganic catalyst materials in both electrodes. The binder materials play role in transporting protons for hydrogen gas and oxygen gas evolution reaction in the cathode and the anode, respectively. In this study, PFSA ionomers with different chemical architectures and equivalent weights were used as binder materials for water electrolysis. The structure property performance relationship was disclosed.
        391.
        2018.11 구독 인증기관·개인회원 무료
        CO2 separation technology for carbon capture, which is one of the hot issues to reduce greenhouse gases from industrial flue gas, has been intensively investigated so far. Despite of several benefits, the membrane technology has some obstacles like large-scale module fabrication, membrane durability, need of pre-treatment or high pressure drive for its industrial application. Also, the power plant flue gas with normally 10~20% of CO2 content should be concentrated upto 99% for being compressed and liquefied to transportable CO2 by pipeline, indicating the need of high selective membrane process as well as high recovery. In this work, the possibility of membrane process for post-combustion treatment in terms of recent technology will be announced. The practically applicable process for CO2 capture also be suggested briefly.
        394.
        2018.10 KCI 등재 SCOPUS 구독 인증기관 무료, 개인회원 유료
        Visible and IR windows require a combination of high optical transparency and superior thermal and mechanical properties. Materials, fabrication and characterization of transparent ceramics for visible/IR windows are discussed in this review. The transparent polycrystalline Y2O3, Y2O3-MgO nanocomposites and MgAl2O4 spinel ceramics are fabricated by advanced ceramic processing and the use of special sintering technologies. Ceramic processing conditions for achieveing fully densified transparent ceramics are strongly dependent on the initial powder characteristics. In addition, appropriate use of sintering technologies, including vacuum sintering, hot-pressing and spark plasama sintering methods, results in outstanding thermal and mechanical properties as well as high optical transparency of the final products. Specifically, the elimination of light scattering factors, including residual pores, second phases and grain boundaries, is a key technique for improving the characteristics of the transparent ceramics. This paper discusses the current research issues related to synthesis methods and sintering processes for yttria-based transparent ceramics and MgAl2O4 spinel.
        4,500원
        400.
        2018.10 KCI 등재 구독 인증기관 무료, 개인회원 유료
        The purpose of this study was to investigate the characteristics of macaroons prepared using natural color materials (Opuntia ficus-indica var. saboten (Re-N), mulberry leaf (Gr-N), pumpkin (Ye-N), and cocoa powder (Br-N)) and corresponding artificial food colorants (red (Re-A), yellow (Ye-A), green (Gr-A) and brown (Br-A)). The moisture content of macaroons prepared using natural color material was higher compared to the macaroons prepared using artificial food colorant. DPPH and ABTS radical scavenging activity was similar in both types of macaroons. Lightness and redness of Re-N, Gr-N, Ye-N, and Br-N macaroons were lower than Re-A, Gr-A, Ye-A and Br-A macaroons. Yellowness of Re-N was higher because of the browning reaction. The texture profile analysis revealed lower hardness when natural color powder was employed. In the sensory evaluation, overall acceptability was not significantly different between natural colored and artificial colored macaroons. As a result, macaroons with the natural color material were softer and showed higher antioxidative activity, however, organoleptic properties were not much different when compared with macaroons with artificial colors. Apparently, it is stated that more studies on the development of macaroons with more enhanced physical functionality and good taste using natural materials should be performed.
        4,000원