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        검색결과 66

        21.
        2015.09 KCI 등재 구독 인증기관 무료, 개인회원 유료
        n-Butanol and ethyl acetate extracts of thermal treatment yam (Dioscorea batatas DECNE.) belonging to the family Dioscoreaceae were measured for their radical scavenging activity and lipid peroxidation inhibition ability. In this study, ethyl acetate extract showed the most potent antioxidant activity evaluated by ferrous ion chelating activity and NO radical scavenging activity. Nevertheless, n-butanol extract was more effective in inhibiting linoleic acid peroxidation. A significant difference between n-butanol extract and ethyl acetate extract in nitrite scavenging activity β-carotene bleaching assays could not be found. Also, the results of this study showed that thermal treatment yam could be used as easily accessible source of natural antioxidants and as a possible food supplement.
        4,000원
        22.
        2015.06 KCI 등재 구독 인증기관 무료, 개인회원 유료
        To better investigate the antioxidative property of thermal treatment yam (Dioscorea batatas DECNE.) in Korea, some established methods were used. 70% Methanol, 70% ethanol and chloroform–methanol (CM, 2:1, v/v) extracts were collected. 70% Methanol extract exhibited stronger antioxidative activity evaluated by ferrous ion chelating activity, NO radical scavenging activity and β-carotene bleaching assays. On the contrary, CM extract was the most effective in inhibiting linoleic acid peroxidation. Yam available in Korea was also analyzed for its bioactive compounds such as lycopene, chlorophyll a, b, tannin, phytic acid and total saponin contents. Total saponin was abundant in thermal treatment, which determined to be 42.52±1.88 mg/g. Based on the results obtained from this study, thermal treatment yam could be used as natural antioxidant source due to its high antioxidant activity and bioactive compound contents.
        4,000원
        23.
        2015.05 KCI 등재 구독 인증기관 무료, 개인회원 유료
        본 연구에서는 피망의 동결 전 가열처리 조건을 선정하 기 위해 열수침지, 과열증기 및 볶음 처리 조건에 따른 품 질 특성 변화를 조사하였다. 피망의 외관, 색도, 경도, 미세 구조 관찰 등의 결과로 각 방법별 두 가지 조건을 선정 후 영양학적 품질 조사를 실시하였다. 가열처리 후 피망의 ΔE 값은 처리 시간에 따라 감소하는 경향을 보였고, 특히 볶음 처리시 감소폭이 큰 것으로 나타났다. 열수침지 및 과열증기 처리에 따른 pH 변화는 적었지만, 볶음 처리 후 감소하였다. 경도는 가열처리 후 대체적으로 감소하는 경 향을 보였고, 열수침지 및 볶음 처리 시간이 길수록 경도 는 급격히 감소하는 경향을 보였다. 피망의 일반성분, 비타 민 C, 유리당 및 유기산 함량은 가열처리 방법 및 처리 시간에 따라 유의적인 영향을 받았다. 비타민 C 함량은 열 수침지>과열증기>볶음 처리 순으로, 처리 시간이 길수록 감소량이 큰 것으로 나타났다. 피망의 수용성 성분인 유리 당 및 유기산 함량은 볶음 처리에 비해 열수침지 및 과열 증기 처리시 감소량이 많았다. Peroxidase 활성은 짧은 시 간의 열수침지(2분) 및 과열증기(3분) 처리에도 약 90% 이 상의 불활성화율을 나타냈지만, 볶음 처리시에는 peroxidase 활성 억제 효과가 20% 이하로 낮았다. 이상의 결과로부터 피망의 가열처리 조건은 색도, 경도, 비타민 C, 유리당 등 변화는 적고 peroxidase 억제 효과가 높은 증기처리법으로 3분간 처리하는 것이 적합할 것으로 판단된다.
        4,000원
        24.
        2015.04 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Response surface methodology (RSM) based on a Box-Behnken Design (BBD) was applied to optimize the thermal-alkaline pre-treatment operating conditions for anaerobic digestion of flotation scum in food waste leachate. Three independent variables such as thermal temperature, NaOH concentration and reaction time were evaluated. The maximum methane production of 369.2 mL CH4/g VS was estimated under the optimum conditions at 62.0°C, 10.1% NaOH and 35.4 min reaction time. A confirmation test of the predicted optimum conditions verified the validity of the BBD with RSM. The analysis of variance indicated that methane production was more sensitive to both NaOH concentration and thermal temperature than reaction time. Thermal-alkaline pretreatment enhanced the improvement of 40% in methane production compared to the control experiment due to the effective hydrolysis and/or solubilization of organic matters. The fractions with molecular weight cut-off of scum in food waste leachate were conducted before and after pre-treatment to estimate the behaviors of organic matters. The experiment results found that thermal-alkaline pre-treatment could reduce the organic matters more than 10kD with increase the organic matters less than 1kD.
        4,000원
        25.
        2015.03 KCI 등재 구독 인증기관 무료, 개인회원 유료
        The aim of this study was to investigate the antioxidant activity of thermal treatment yam (Dioscorea batatas DECNE.) in Korea. Thermal treatment yam was extracted by different solvents including 70% methanol, 70% ethanol and chloroform–methanol mixture (CM, 2:1, v/v). Then color property, total phenol content and antioxidant activity were analyzed. Yam possessed high L* value and H° value, which were 54.92±2.18 and 73.20±0.77, respectively. Thermal treatment yam exhibited great antioxidant activity evaluated by ABTS [2,2′ -azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) diammonium salt] radical scavenging activity, DPPH (2,2-diphenyl-1-picrylhydrazyl) radical scavenging activity, reducing power, and ferric reducing antioxidant power. Total phenol contents of various extracts from thermal treatment yam increased in the following order: 70% methanol extract (63.53±0.33 mg CAE/g), 70% ethanol extract (69.47±1.00 mg CAE/g) and CM extract (97.49±0.66 mg CAE/g), respectively. The same trend was also could be found in antioxidant activity assays except for reducing power assay. These results implied that these extracts from thermal treatment yam might be useful to take a good part in prevention of human diseases and aging.
        4,000원
        26.
        2015.03 KCI 등재 구독 인증기관 무료, 개인회원 유료
        In this study, the thermal treatment yam (Dioscorea batatas DECNE.) was analyzed for its proximate and nutritional compositions including mineral, vitamin, amino acids and fatty acids. Thermal treatment yam is mainly consisted of carbohydrate (70.3%) with small amounts of crude protein (15.8%), crude ash (5.1%) and crude fat (1.6%). It was found to be a good source of essential minerals such as K (1100.2 mg/100 g), Mg (99.4 mg/100 g), Ca (54.8 mg/100 g) and Na (44.9 mg/100 g) but Zn (4.8 mg/100 g) and Fe (0.2 mg/100 g) content was low. Little amounts of vitamin E (8.3 mg/100 g), vitamin C (3.5 mg/100 g) and vitamin B1 (2.1 mg/100 g) could be found. The amino acid analysis revealed that the yam was superior with respect to serine (1454.2 mg%), lysine (684.6 mg%) and histidine (684.6 mg%). Essential amino acids were calculated to be 2849.3 mg%. The amino acid profiles showed that thermal treatment yam is limiting in isoleucine and phenylaline. Linoleic acid was the most predominant fatty acids with the value of 47.3% followed by palmitic acid (24.7%) and oleic acid (12.7%). And the unsaturated fatty acids including oleic acid and linoleic acid were present in big quantities in thermal treatment yam.
        4,000원
        27.
        2015.01 KCI 등재 구독 인증기관 무료, 개인회원 유료
        In this study, in order to improve the thermal and electrical properties of epoxy/graphene nanoplatelets (GNPs), surface modifications of GNPs are conducted using silane coupling agents. Three silane coupling agents, i.e. 2-(3,4-epoxycyclohexyl)-ethyltrimethoxysilane (ETMOS), 3-glycidoxypropyltriethoxysilane (GPTS), and 3-glycidoxypropyltrimethoxysilane (GPTMS), were used. Among theses, GPTMS exhibits the best modification performance for fabricating GNP-incorporated epoxy composites. The effect of the silanization is evaluated using transmission electron microscopy (TEM), scanning electron microscopy, thermogravimetric analysis, and energy dispersive X-ray spectroscopy. The electrical and thermal conductivities are characterized. The epoxy/silanized GNPs exhibits higher thermal and electrical properties than the epoxy/raw GNPs due to the improved dispersion state of the GNPs in the epoxy matrix. The TEM microphotographs and Turbiscan data demonstrate that the silane molecules grafted onto the GNP surface improve the GNP dispersion in the epoxy.
        4,000원
        28.
        2014.06 KCI 등재 구독 인증기관 무료, 개인회원 유료
        FeS2 has been widely used for cathode materials in thermal battery because of its high stability and currentcapability at high operation temperature. Salts such as a LiCl-KCl were added as a binder for improving electrical per-formance and formability of FeS2 cathode powder. In this study, the effects of the addition of Li2O in LiCl-KCl binderon the formability of FeS2 powder compact were investigated. With the increasing amount of Li2O addition to LiCl-KClbinder salts, the strength of the pressed compacts increased considerably when the powder mixture were pre-heat-treatedabove 350oC. The heat-treatment resulted in promoting the coating coverage of FeS2 particles by the salts as Li2O wasadded. The observed coating as Li2O addition might be attributed to the enhanced wettability of the salt rather than itsreduced melting temperature. The high strength of compacts by the Li2O addition and pre-heat-treatment could improvethe formability of FeS2 raw materials.
        4,000원
        29.
        2013.02 구독 인증기관 무료, 개인회원 유료
        Ocean discharge of sewage sludge, which started in the year of 1993 in Korea, was stopped in the beginning of 2012, Landfill of sewage sludge was also prohibited in 2003 owing to public acceptance of the lanfill sites, and partially reopened in 2007 due to the necessity of organic component in sludge to produce methane gas. Sludge recycle ratio will increase in sewage sludge treatment by volume reduction and drying, and then recycle of the thermal energy as fuel in power plant and also material as raw material of cement. Several drying processes are compared with reasoning and an appropriate drying sequence is suggested.
        4,000원
        30.
        2012.10 KCI 등재 SCOPUS 구독 인증기관 무료, 개인회원 유료
        Metal nanowires can be coated on various substrates to create transparent conducting films that can potentially replace the dominant transparent conductor, indium tin oxide, in displays, solar cells, organic light-emitting diodes, and electrochromic windows. One issue with these metal nanowire based transparent conductive films is that the resistance between the nanowires is still high because of their low aspect ratio. Here, we demonstrate high-performance transparent conductive films with silver nanofiber networks synthesized by a low-cost and scalable electrospinning process followed by two-step sequential thermal treatments. First, the PVP/AgNO3 precursor nanofibers, which have an average diameter of 208 nm and are several thousands of micrometers in length, were synthesized by the electrospinning process. The thermal behavior and the phase and morphology evolution in the thermal treatment processes were systematically investigated to determine the thermal treatment atmosphere and temperature. PVP/AgNO3 nanofibers were transformed stepwise into PVP/Ag and Ag nanofibers by two-step sequential thermal treatments (i.e., 150˚C in H2 for 0.5 h and 300˚C in Ar for 3 h); however, the fibrous shape was perfectly maintained. The silver nanofibers have ultrahigh aspect ratios of up to 10000 and a small average diameter of 142 nm; they also have fused crossing points with ultra-low junction resistances, which result in high transmittance at low sheet resistance.
        4,000원
        31.
        2011.09 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Kenaf fibers, cellulose-based natural fibers, were used as precursor for preparing kenafbased carbon fibers. The effects of carbonization temperature (700℃ to 1100℃) and chemical pre-treatment (NaOH and NH4Cl) at various concentrations on the thermal change, chemical composition and fiber morphology of kenaf-based carbon fibers were investigated. Remarkable weight loss and longitudinal shrinkage were found to occur during the thermal conversion from kenaf precursor to kenaf-based carbon fiber, depending on the carbonization temperature. It was noted that the alkali pre-treatment of kenaf with NaOH played a role in reducing the weight loss and the longitudinal shrinkage and also in increasing the carbon content of kenaf-based carbon fibers. The number and size of the cells and the fiber diameter were reduced with increasing carbonization temperature. Morphological observations implied that the micrometer-sized cells were combined or fused and then re-organized with the neighboring cells during the carbonization process. By the pre-treatment of kenaf with 10 and 15 wt% NaOH solutions and the subsequent carbonization process, the inner cells completely disappeared through the transverse direction of the kenaf fiber, resulting in the fiber densification. It was noticeable that the alkali pre-treatment of the kenaf fibers prior to carbonization contributed to the forming of kenaf-based carbon fibers.
        4,000원
        32.
        2010.06 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Boron doped fullerene C60 (B:C60) films were prepared by the thermal evaporation of C60 powder using argon plasma treatment. The morphology and structural characteristics of the thin films were investigated by scanning electron microscope (SEM), Fourier transform infra-red spectroscopy (FTIR) and x-ray photo electron spectroscopy (XPS). The electrochemical application of the boron doped fullerene film as a coating layer for silicon anodes in lithium ion batteries was also investigated. Cyclic voltammetry (CV) measurements were applied to the B:C60 coated silicon electrodes at a scan rate of 0.05 mVs-1. The CV results show that the B:C60 coating layer act as a passivation layer with respect to the insertion and extraction of lithium ions into the silicon film electrode.
        3,000원
        33.
        2009.04 KCI 등재 구독 인증기관 무료, 개인회원 유료
        The effects of thermal treatment conditions on ADU (ammonium diuranate) prepared by SOL-GEL method, so-called GSP (Gel supported precipitation) process, were investigated for kernel preparation. In this study, ADU compound particles were calcined to particles in air and Ar atmospheres, and these particles were reduced and sintered in 4%-/Ar. During the thermal calcining treatment in air, ADU compound was slightly decomposed, and then converted to phases at . At , the phase appeared together with . After sintering of theses particles, the uranium oxide phases were reduced to a stoichiometric . As a result of the calcining treatment in Ar, more reduced-form of uranium oxide was observed than that treated in air atmosphere by XRD analysis. The final phases of these particles were estimated as a mixture of and .
        4,000원
        34.
        2009.03 KCI 등재 구독 인증기관 무료, 개인회원 유료
        The thermal stability and mechanical properties of Nephila clavata and Bassaniana decorata spider silks were measured and compared with those of aramid and polyester fibers. The thermal stability of the spider silk was lower than those of the commercial aramid and polyester fibers. However, the mechanical properties of the spider silk were far superior to that of the polyester fiber. The effect of the water content of the spider silk on its thermal stability and mechanical property was examined by conducting the silk to heat treatment at 100℃ under vacuum for various times. The results indicated that spider silk subjected to heat treatment for 1.5 hr had excellent thermal stability and mechanical property.
        4,000원
        38.
        2002.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        In order to investigate the effect of irradiation by 60Co-γrays as well as the e thermal treatment on the dielectric deterioration in ethylene propylene rubber, insulating material for electric cables used in atomic power plants, charging discharging current, residual built- up voltage and dielectric properties are measu discussed in this study. Variance in the characteristic of relative dielectric constant as a function of tem was observed in relatively high dose of irradiation. Since glass transition tem appeared at tens of degree Celsius below zero, the characteristic is attributed orientation polarization. Dielectric loss is generally increased, with increasing d irradiation in the characteristic of dielectric loss as a function of temperature, No d loss by thermal treatment was observed. Dielectric resistance decreases with increa of irradiation in the characteristic of charging current as a function of temperature be considered that dielectric resistance seems to be recovered by thermal treatm characteristic of discharging current as a function of time in the specimen less ir become similar to that of the unirradiated, when thermal treated. A peak is shown residual built- up voltage as a function of time, and the corresponding time of the shorten as increasing dose of irradiation. It is also observed that the corresponding the peak is lengthened by thermal treatment.
        4,000원
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