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        검색결과 1,829

        341.
        2017.08 KCI 등재 구독 인증기관 무료, 개인회원 유료
        This study investigated the effects of Goami 2 on the properties of Garaetteok. The moisture, crude protein, crude lipid and crude ash contents of the rice were 16.02, 5.40, 1.87 and 0.77%, respectively. The amylose contents (32.16%) and total dietary fiber contents (9.03%) were the highest in Goami 2. The water binding capacity of Goami 2 (167.84%) was higher than general rice flour. Using a rapid visco analyzer (RVA), the initial pasting temperature of Goami 2 was found to be the highest; also, the peak viscosities of Goami 2 were higher than general rice powder. To assess the effect of Goami 2 on the quality characteristics of Garaetteok, the rice-cake was made by adding various amounts of Goami 2 (0, 10, 20, 30, and 40% w/w) to rice. It was observed that higher the amount of added Goami 2, lower were the grades. In terms of the color values of Goami 2 addition, the L-values of Garaetteok were lower with increasing amount of Goami 2; addition of 40% Goami 2 had the lowest value. The textural properties (hardness) also showed that tteok containing the greater amounts of Goami 2 were considerably harder compared with the control. Sensory preference tests revealed that addition of less Goami 2 had the highest scores for appearance, color and overall acceptability, and the Goami 2 added was lower than control. Therefore, as compared to others cultivars, rice flour proved the most acceptable for the preparation of Garaetteok with cultivar rice.
        4,000원
        342.
        2017.08 KCI 등재 구독 인증기관·개인회원 무료
        This study added stevia leaf powder at ratios of 0.5, 1.0, 1.5, and 2.0 percent to Omija-pyun (Schisandra chinensis Jelly) as a natural low-calorie sweetener instead of sugar which is added to Omija-pyun in considerable amounts to evaluate quality characteristics and antioxidant activities compared to the control group with the addition of sugar. Moisture content of Omija-pyun expanded by increasing the measurement of stevia leaf powder (p<0.001), pH (p<0.01) and sugar content (p<0.001) decreased. L-values and b-values revealed a tendency to increase by adding more stevia leaf powder, but a-value revealed a tendency to decrease (p<0.001). Hardness (p<0.001) and chewiness (p<0.05) decreased by adding more stevia leaf powder. Based on the consumer preference evaluation, Omija-pyun with the addition of 0.5 percent stevia leaf powder was the most preferable in terms of color and flavor (p<0.001). The control group and Omija-pyun with the addition of 0.5 percent stevia leaf powder was the most preferable in terms of taste and texture (p<0.001). There were significant differences in the organoleptic properties except hardness between the samples by quantitative descriptive analysis. The control group revealed the highest preference in terms of redness and transparency, and redness and transparency tended to decrease by adding more stevia leaf powder (p<0.001). Organoleptic properties on bitterness and sourness were enhanced by adding more stevia leaf powder in the principal component analysis (PCA). Regarding antioxidant properties, total phenol compounds and flavonoid contents of Omija-pyun increased by adding more stevia leaf powder, and DPPH radical scavenging capacity also increased (p<0.001). Based on results, it is preferable to serve Omija-pyun with the addition of 1.0 percent stevia leaf powder instead of sugar within the context of quality and antioxidant activity.
        343.
        2017.08 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Fe3O4/Fe/graphene nanocomposite powder is synthesized by electrical wire explosion of Fe wire and dispersed graphene in deionized water at room temperature. The structural and electrochemical characteristics of the powder are characterized by the field-emission scanning electron microscopy, X-ray diffraction, Raman spectroscopy, field-emission transmission electron microscopy, cyclic voltammetry, and galvanometric discharge-charge method. For comparison, Fe3O4/Fe nanocomposites are fabricated under the same conditions. The Fe3O4/Fe nanocomposite particles, around 15-30 nm in size, are highly encapsulated in a graphene matrix. The Fe3O4/Fe/graphene nanocomposite powder exhibits a high initial charge specific capacity of 878 mA/g and a high capacity retention of 91% (798 mA/g) after 50 cycles. The good electrochemical performance of the Fe3O4/Fe/graphene nanocomposite powder is clearly established by comparison of the results with those obtained for Fe3O4/Fe nanocomposite powder and is attributed to alleviation of volume change, good distribution of electrode active materials, and improved electrical conductivity upon the addition of graphene.
        4,000원
        344.
        2017.08 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Titanium alloys have high specific strength, excellent corrosion and wear resistance, as well as high heatresistant strength compared to conventional steel materials. As intermetallic compounds based on Ti, TiAl alloys are becoming increasingly popular in the aerospace field because these alloys have low density and high creep properties. In spite of those advantages, the low ductility at room temperature and difficult machining performance of TiAl and Ti3Al materials has limited their potential applications. Titanium powder can be used in such cases for weight and cost reduction. Herein, pre-forms of Ti-Al-xMn powder alloys are fabricated by compression forming. In this process, Ti powder is added to Al and Mn powders and compressed, and the resulting mixture is subjected to various sintering temperature and holding times. The density of the powder-sintered specimens is measured and evaluated by correlation with phase formation, Mn addition, Kirkendall void, etc. Strong Al-Mn reactions can restrain Kirkendall void formation in Ti-Al-xMn powder alloys and result in increased density of the powder alloys. The effect of Al-Mn reactions and microstructural changes as well as Mn addition on the high-temperature compression properties are also analyzed for the Ti-Al-xMn powder alloys.
        4,000원
        345.
        2017.06 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Fe-6.5 wt.% Si alloys are widely known to have excellent soft magnetic properties such as high magnetic flux density, low coercivity, and low core loss at high frequency. In this work, disc-shaped preforms are prepared by spark plasma sintering at 1223 K after inert gas atomization of Fe-6.5 wt.% Si powders. Fe-6.5 wt.% Si sheets are rolled by a powder hot-rolling process without cracking, and their microstructure and soft magnetic properties are investigated. The microstructure and magnetic properties (saturation magnetization and core loss) of the hot-rolled Fe-6.5 wt.% Si sheets are examined by scanning electron microscopy, electron backscatter diffraction, vibration sample magnetometry, and AC B–H analysis. The Fe-6.5 wt.% Si sheet rolled at a total reduction ratio of 80% exhibits good soft magnetic properties such as a saturation magnetization of 1.74 T and core loss (W5/1000) of 30.7 W/kg. This result is caused by an increase in the electrical resistivity resulting from an increased particle boundary density and the oxide layers between the primary particle boundaries.
        4,000원
        346.
        2017.06 KCI 등재 구독 인증기관 무료, 개인회원 유료
        This experiment was carried out to enhance the availability of blackberry. Since it is difficult to use blackberry as a fresh fruit, we investigated the quality characteristics of blackberry powder obtained by various drying methods (freeze drying and hot-air drying at 40~80℃). The L- and b-values of freeze-dried powder was higher than hot-air dried powder. The pH (3.2) was lowest and the acidity (14.4%) was highest in freeze-dried powder. In freeze drying, the brix degree was 65.7 °Bx, but it increased from 54.7 °Bx to 68.5 °Bx with increasing temperature during hot air drying. The total polyphenol and flavonoids contents were the highest in freeze-dried powder, at 9.3 and 6.2 mg/g, respectively. The levels increased as temperature increased in hot air drying. Anthocyanin content in freeze-dried powder was 8.51 mg/g, while it sharply decreased to 1.17~2.45 mg/g in hot-air drying. Vitamin C content in freeze drying (979.4 μg/g) was higher than that in hot-air drying (48.3~303.2 μg/g). The sample concentration required for 50% reduction of DPPH free radical scavenging (RC50) was 79.7 μg/mL in freeze drying, and showed high antioxidant activity. Also it decreased from 122.4 μg/mL to 87.7 μg/mL with temperature increase during hot air drying. We therefore conclude from the above results that freeze drying is more suitable for the production of blackberry powder, because this method showed high value of chromaticity, total polyphenol, flavonoid, anthocyanin content, vitamin C and antioxidant activity.
        4,000원
        347.
        2017.06 KCI 등재 구독 인증기관 무료, 개인회원 유료
        An agricultural waste, pomegranate (Punica granatum L.) peel is known to be rich in total phenolics, which are flavonoids having strong antioxidant effects. In this study, pomegranate peel sponge cakes were prepared with varying ratios of freeze dried pomegranate peel powder (0, 1, 3, 5, 7% (w/w)) to examine their effect on quality characteristics, retrogradation and antioxidant activities. The specific gravity and moisture contents of 3, 5, and 7% pomegranate peel powder showed higher values than the control and 1% group. Addition of pomegranate peel powder increased the batter yield, while there was a significant decrease in baking loss. Increasing pomegranate peel powder content significantly decreased the lightness (L) (from 75.03 to 57.04) and pH values, whereas redness (a), yellowness (b) and ΔE were increased. Increasing concentration of the peel powder also increased the hardness and chewiness, while the springiness and cohesiveness decreased. Considering the Avrami equation, Avrami exponene (n) decreased from 1.8055 (control) to 0.9199 (7% pomegranate peel powder). Time constant (1/k) was lowest in control (at 17.64) and highest in the 7% group (39.84). Total polyphenol, flavonoid content, DPPH and ABTS radical scavenging activities significantly increased with increments in the content of pomegranate peel powder. A sensory evaluation by the 7-point scaling method showed that the sponge cake containing 7% pomegranate peel powder had the highest scores in color, flavor, sweetness, chewiness and overall acceptability. Hence, it is considered that sponge cake supplemented with 7% pomegranate peel powder is the most appropriate for quality characteristics, retrogradation and antioxidant activities.
        4,500원
        348.
        2017.06 KCI 등재 SCOPUS 구독 인증기관 무료, 개인회원 유료
        Photoelectron-hole separation efficiency plays an important role in the enhancement of the photocatalytic activity of photocatalysts towards the degradation of organic molecules. In this study, TiO2/TiOF2 heterostructured composite powders with suitable band structures, which structures are able to separate photoelectron-hole pairs, have been synthesized using a simple and versatile ultrasonic spray pyrolysis process. In addition, their phase volume fractions have been controlled by varying the pyrolysis temperature from 400 oC to 800 oC. The structural and optical properties of the synthesized powders have been characterized by X-ray diffraction, scanning electronic microscopy and UV-vis spectroscopy. The powder with a phase volume ratio close to 1, compared with single TiOF2 and other composite powders with different phase volume fractions, was found to have superior photocatalytic activity for the degradation of rhodamine B. This result shows that the TiO2/TiOF2 heterostructure promotes the separation of the photoinduced electrons and holes and that this powder can be applicable to environmental cleaning applications.
        4,000원
        349.
        2017.06 KCI 등재 구독 인증기관 무료, 개인회원 유료
        We investigated the antioxidant, physicochemical, and sensory characteristics of dried type sodium-reduced bibimbap using dandelion complex powder (DCP). DCP is known to add moisture to the skin and relieve symptoms of atopic dermatitis. The sodium content of the standard sample was 1,110.87 mg per serving. The sodium was significantly reduced by 30%, resulting in 762.62 mg of sodium for the reduced sodium group (p<0.05). The ash contents of the standard sample group with DCP showed the highest value (3.17%) in all samples and was affected by minerals of DCP (p<0.05). The total flavonoid contents and ABTS radical scavenging activity, indicators of antioxidant, anticancer and antibacterial activities, showed significantly high activities with addition of DCP (p<0.05). In the sensory results, bulgogi and savory flavor of the samples with DCP showed significantly higher values, and samples with DCP received the highest scores for after-taste. All samples were confirmed to be microbiologically safe according to the food code applied to food manufacturers. Pathogenic microorganisms tests were either negative or not detected in all samples.
        4,000원
        350.
        2017.06 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Transparent conducting electrodes (TCEs) are attracting considerable attention as an important component for emerging optoelectronic applications such as liquid crystal displays, touch panels, and solar cells owing to their attractive combination of low resistivity (< 10-3 Ω cm) and high transparency (>80%) in the visible region. The solutionbased process has unique properties of an easy fabrication procedure, scalability, and low cost compared to the conventional vacuum-based process and may prove to be a useful process for fabricating TCEs for future optoelectronic applications demanding large scale and flexibility. In this paper, we focus on the introduction of a solution-based process for TCEs. In addition, we consider the powder materials used to fabricate solution-based TCEs and strategies to improve their transparent conducting properties.
        4,200원
        351.
        2017.06 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Harmonic structure materials are materials with a core–shell structure having a shell with a small grain size and a core with a relatively large grain size. They are in the spotlight because their mechanical properties reportedly feature strength similar to that of a sintered powder with a fine grain size and elongation similar to that of a sintered powder with a coarse grain size at the same time. In this study, the tensile properties, microstructure, and stretchflangeability of harmonic structure SUS304L made using powder metallurgy are investigated to check its suitability for automotive applications. The harmonic powders are made by mechanical milling and sintered using a spark plasma sintering method at 1173 K and a pressure of 50 MPa in a cylindrical die. The sintered powders of SUS304L having harmonic structure (harmonic SUS304L) exhibit excellent tensile properties compared with sintered powders of SUS304L having homogeneous microstructure. In addition, the harmonic SUS304L has excellent stretch-flangeability compared with commercial advanced high-strength steels (AHSSs) at a similar strength grade. Thus, the harmonic SUS304L is more suitable for automotive applications than conventional AHSSs because it exhibits both excellent tensile properties and stretch-flangeability.
        4,000원
        352.
        2017.06 KCI 등재 구독 인증기관 무료, 개인회원 유료
        복분자, 갈근 및 녹차 추출분말이 각각 1%(w/w)로 첨가된 조미액으로 제조된 한우 육포의 품질특성 및 항산화 활성을 비교하였다. 복분자, 갈근 및 녹차 추출분말이 첨가된 조미액의 항산화 활성은 무첨 가구에 비해 유의적으로 높았다. 식물류 추출분말이 첨가된 육포의 전단가는 대조구에 비해 유의적으로 낮았으며, 색차(ΔE)는 시료 간에 미미하였으며, 전반적인 기호도는 녹차 추출분말이 첨가된 육포 (G-BJ)에서 다소 높게 평가되었다. 육포의 저장과정 중 수분활성도는 저장 2주째에 대조구에서 유의적 으로 증가되었으나, 식물 추출분말이 첨가된 육포는 저장 1주에 비해 유의적인 증감을 보이지 않았다. 저장 4주 경과 후에는 모든 시료에서 수분활성도가 다소간 증가되는 경향이었다. 식물 추출분말이 첨가 된 육포를 4주간 실온에 저장하는 동안 지질과산화물의 함량은 유의적으로 증가하였다. G-BJ는 4주간 저장되었을 때 2주간 저장된 시료에 비해 유의적인 증가 현상을 보이지 않았다. 식물 추출분말이 첨가 된 육포의 항산화 활성은 대조구에 비해 유의적으로 높았으며, 특히 G-BJ에서 가장 높았다. 한우 육포 의 제조 시 식물 추출분말의 첨가는 육포의 전단가 감소와 항산화 활성을 증가시킴으로써 육포의 품질 향상에 효과적일 것으로 예상된다.
        4,600원
        353.
        2017.06 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Porous polytetrafluoroethylene (PTFE) thin films are fabricated by spin-coating using a dispersion solution containing PTFE powders, and their crystalline properties are investigated after thermal annealing at various temperatures ranging from 300 to 500°C. Before thermal annealing, the film is densely packed and consists of many granular particles 200-300 nm in diameter. However, after thermal annealing, the film contains many voids and fibrous grains on the surface. In addition, the film thickness decreases after thermal annealing owing to evaporation of the surfactant, binder, and solvent composing the PTFE dispersion solution. The film thickness is systematically controlled from 2 to 6.5 μm by decreasing the spin speed from 1,500 to 500 rpm. A triboelectric nanogenerator is fabricated by spin-coating PTFE thin films onto polished Cu foils, where they act as an active layer to convert mechanical energy to electrical energy. A triboelectric nanogenerator consisting of a PTFE layer and Al metal foil pair shows typical output characteristics, exhibiting positive and negative peaks during applied strain and relief cycles due to charging and discharging of electrical charge carriers. Further, the voltage and current outputs increase with increasing strain cycle owing to accumulation of electrical charge carriers during charge-discharge.
        4,000원
        357.
        2017.05 KCI 등재 SCOPUS 구독 인증기관 무료, 개인회원 유료
        Abstract Y2Ti2O7 nanoparticles (0.3 mol%) have been successfully synthesized by the co-precipitation process. The samples, adjusted to pH7 with ammonia solution as catalyst and calcined at 700~900 ℃, exhibit very fine particles with close to spherical shape and average size of 10-30 nm. It was possible to control the size of the synthesized Y2Ti2O7 particles by manipulating the conditions. The Y2Ti2O7 nanoparticles were coated on a glass substrate by a dipping coating process with inorganic binder. The Y2Ti2O7 solution coated on the glass substrate had excellent adhesion of 5B; pencil hardness test results indicated an excellent hardness of 6H. The thickness of the thick film was about 30 μm. Decomposition of MB on the Y2Ti2O7 thin film shows that the photocatalytic properties were excellent.
        4,000원