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        검색결과 17

        1.
        2023.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Seawater evaporation and purification powered by solar energy are considered as a promising approach to alleviate the global freshwater crisis, and the development of photothermal materials with high efficiency is imminent. In this study, cellulose nanofiber (CNF)/MXene/Ni chain (CMN) aerogels were successfully synthesized by electrostatic force and hydrogen bond interaction force. CMN10 achieved a favorable evaporation rate as high as 1.85 kg m− 2 h− 1 in pure water, and the corresponding evaporation efficiency could be up to 96.04%. Even if it is applied to seawater with multiple interference factors, its evaporation rate can still be 1.81 kg m− 2 h− 1. The superior seawater evaporation activity origins from the promoted separation of photoexcited charges and photothermal conversion by the synergy of Ni chain and MXene, as well as the water transport channel supported by the 3D structure frame of CNF. Most importantly, CMN aerogel can maintain water vapor evaporation rates above 1.73 kg m− 2 h− 1 under extreme conditions such as acidic (pH 2) and alkaline (pH 12) conditions. In addition, various major ions, heavy metals and organic pollutants in seawater can be rejected by CMN10 during desalination, and the rejection rates can reach more than 99.69%, ensuring the purity of water resources after treatment. This work shows the great potential of CMN aerogel as a high-efficiency solar evaporator and low-cost photothermal conversion material. Cellulose nanofiber (CNF)/MXene/Ni chain (CMN) aerogels demonstrated high evaporation of water from sea water.
        4,300원
        3.
        2020.09 KCI 등재 구독 인증기관 무료, 개인회원 유료
        These experiments were to investigate the variations of rye on forage quality, productivity and β-carotene concentration affected by maturity in Pyeongchang region. Limited information are available about how forage quality and β-carotene content are affected by various factors. Samples were collected from rye harvested every 5 days, from April 25 to May 31 (April 25, April 30, May 4, May 9, May 15, May 21, May 25 and May 31). Dry matter (DM) content, plant height, DM yield and total digestible nutrient (TDN) yield increased continuously with the progressed maturity. However, crude protein (CP) content, in vitro dry matter digestibility (IVDMD) and relative feed value (RFV) decreased markedly with the delay of harvesting, while TDN content decreased from April 25 till May 15, then followed by a stable fluctuation. Conversely, acid detergent fiber (ADF) and neutral detergent fiber (NDF) value increased and then fluctuated slightly after blooming stage. For quality of plant parts, stem contained the lowest CP content and RFV value, and the highest ADF and NDF contents compared with other parts, while the grain showed the higher CP, IVDMD, RFV and lower fiber contents than others. With the plant matured, leaf proportion decreased while stem and grain proportion increased, and feed value of all the three parts decreased till blooming stage and followed by a stable phase. β-carotene concentration showed its highest on jointing stage, and then fell down sharply on the sequential stages. In conclusion, harvest around May 15 (blooming) is proper for forage rye if directly consumed by livestock as green chop in Pyeongchang under the consideration of both nutritive yield and forage quality.
        4,000원
        4.
        2019.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        This study was conducted to investigate the effect of whole crop rice based TMR on the meat quality of Korean Native Cattle (Hanwoo). Sixteen Hanwoo steers (average 8 months old) were divided into the control group (commercially marketed TMR) and the WCR-TMR group (whole crop rice based TMR). Feeding trials were carried out up to 30 months of age, and after slaughter, the strip loin were collected and analyzed for meat quality. There were no significant differences in proximate compositions of Hanwoo (P>0.05), and crude protein, crude fat and crude ash were 19.51∼20.23 %, 11.53∼11.35 % and 1.10∼1.12 %, respectively. There was no significant difference in water holding capacity and cooking loss between treatments (P>0.05), but it was slightly lower in the control group. Among the various functional components in meat, β-carotene was not detected, but α-tocopherol was significantly higher in WCR-TMR group and vitamin A content in control (P<0.05). The a*-value in the meat color index decreased significantly with longer storage period in the control group, whereas the WCR-TMR fed group showed no significant difference (P>0.05) according to the storage period. There were no difference between the treatments in the TBARS (2-Thiobarbituric acid reactive substances) value used as an indicator of lipid oxidation and in fatty acid content. But the control group had high myristic acid content, whereas the WCR-TMR supplemented group showed higher oleic acid and linoleic acid content. In conclusion, feeding of WCR based-TMR increased the α-tocopherol content, which is a functional ingredient in meat, and the other components were not significantly different from the control. Therefore, it was judged that there was no significant difference between WCR based and conventional TMR in meat quality characteristics.
        4,000원
        5.
        2019.06 KCI 등재 구독 인증기관 무료, 개인회원 유료
        This experiment was conducted to investigate the effect of whole crop rice (WCR) based TMR on growth performance and carcass characteristics of Hanwoo steers. WCR “Yeongwoo”was harvested at yellow ripen stage and ensiled for 60 days. The crude protein (CP), acid detergent fiber (ADF), neutral detergent fiber (NDF), in vitro dry matter digestibility (IVDMD) and total digestible nutrient (TDN) content was 8.4 %, 28.0 %, 53.8 %, 72.4 % and 66.8 %, respectively. For silage quality, pH was 4.37 and lactic and butyric acid content were 2.84 and 0.04 % in DM. Sixteen Hanwoo steers (8-mon-old) were allocated into either a control (commercial TMR) and WCR-TMR (WCR-based TMR) group. The TMR were fed according to the feeding stage phase: growing (Initiate∼14 month), early fattening (15 month∼21 month) and late fattening (22 month∼30 month). The body weight of control group increased (P<0.05) until early fattening stage, but late growing stage of WCR-TMR group was higher than that of control (P<0.05). Average daily gain (ADG) was significantly greater (P<0.05) in WCR-TMR group (total 0.78 kg/head) compared to control (total 0.66 kg/head) except for late fattening stage. The marketing weight and carcass weight were higher in WCR-TMR group (726 vs 765 kg; 417.8 vs 450.4 kg). The back fat thickness (11.75 vs 13.00 mm), Longissimus dorsi area (88.00 vs 89.88 ㎠) and yield index (65.87 vs 64.30) were not different between the two groups (P>0.05) and also no difference in meat yield grade (A : B : C = 2 : 4 : 2). Marbling score (4.00 vs 4.13), meat color (4.75 vs 4.75), fat color (3.13 vs 2.88), texture (1.25 vs 1.50) and maturity (2.00 vs 2.00) were not significant difference between the two groups and meat quality grade (1++:1+:1:2:3=0:2:4:2:0) was also not different. In conclusion, TMR feeding based on WCR silage showed superiority in carcass yield and ADG compared to control TMR. It is considered that the use of WCR for feed is a necessary option for the substitution of the imported forages and the government's policy for rice production adjustment.
        4,000원
        12.
        2004.09 KCI 등재 구독 인증기관 무료, 개인회원 유료
        본 연구는 동충하초속균의 자실체 인공 재배를 위한 기초자료를 얻고자 제주도 한라산에서 채집한 Cordyceps longissima, C. militaris, C. pruinosa 등 야생 동충하초의 형태적, 생리적 특성조사를 수행하였다. Cordyceps longissima : 지좌는 숙주에서 1~2개 발생하며 곤봉형 또는 불규칙형으로 표면이 다소 거칠고 적갈색을 띤다. 두부는 23~59×6~8 ㎜이며, 병부는 원통형으로 37~151×2.5~4.0 ㎜이다. 자낭각은 묻힌형으로 553~600×215~270 ㎛. 자낭은 가는 원통형으로 330~510×5~6 ㎛이며, 자낭포자는 11~13×1.4~1.8 ㎛이다. 자실체는 매미목 매미과의 곤충에서 발생하였다. 균사 생장은 MCM 배지에서 25℃, 4주 배양시 73 ㎜이며, 균사의 색택은 진황색을 나타내었다. 탄소원으로는 단당류인 glucose, 질소원으로는 potassium nitrate를 가장 잘 이용하였다. C. militaris : 지좌는 숙주에서 1~3개 발생하며 곤봉형으로 주황색을 띤다. 두부는 9~23×6~8㎜이며, 병부는 원통형으로 27~30×6~7 ㎜이다. 자낭각은 반묻힌형으로 465~510×260~310 ㎛. 자낭은 가는 원통형으로 320~385×4.2~4.8 ㎛이며, 자낭포자는 2.2~4.5×1.2~1.4 ㎛이다. 자실체는 나비목 곤충의 번데기에서 발생하였다. 균사 생장은 PDA 배지에서 25℃, 4주 배양시 71 ㎜이며, 균사의 색택은 연노랑색을 나타내었다. 탄소원으로는 단당류인 frucose, 질소원으로는 potassium nitrate를 가장 잘 이용하였다. C. pruinosa : 지좌는 숙주에서 1개 발생하며 곤봉형으로 주홍색을 띤다. 두부는 7~9×3~4이며, 병부는 원통형으로 13~22× 2~3 ㎜이다. 자낭각은 반묻힌형으로 350~520×130~310 ㎛. 자낭은 원통형으로 256~270×5~6㎛이며, 자낭포자는 3.2~5.1×0.8~1.3 ㎛이다. 자실체는 나비목 곤충의 번데기에서 발생하였다. 균사 생장은 PDA 배지에서 25℃, 4주 배양시 60 ㎜이며, 균사의 색택은 연붉은색을 나타내었다. 탄소원으로는 단당류인 arabinose와 mannose, 질소원으로는 sodium nitrite를 가장 잘 이용하였다.
        4,000원
        13.
        2002.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Nanostructured high strength metastable Al-, Mg- and Ti-based alloys containing different amorphous, quasicrystalline and nanocrystalline phases are synthesized by non-equilibrium processing techniques. Such alloys can be prepared by quenching from the melt or by powder metallurgy techniques. This paper focuses on one hand on mechanically alloyed and ball milled powders containing different volume fractions of amorphous or nano-(quasi)crystalline phases, consolidated bulk specimens and, on the other hand. on cast specimens containing different constituent phases with different length-scale. As one example. - based metallic glass matrix composites are produced by mechanical alloying of elemental powder mixtures containing up to 30 vol.% particles. The comparison with the particle-free metallic glass reveals that the nanosized second phase oxide particles do not significantly affect the glass-forming ability upon mechanical alloying despite some limited particle dissolution. A supercooled liquid region with an extension of about 50 K can be maintained in the presence of the oxides. The distinct viscosity decrease in the supercooled liquid regime allows to consolidate the powders into bulk samples by uniaxial hot pressing. The additions increase the mechanical strength of the composites compared to the metallic glass. The second example deals with Al-Mn-Ce and Al-Cu-Fe composites with quasicrystalline particles as reinforcements, which are prepared by quenching from the melt and by powder metallurgy. (x =5,6,7) melt-spun ribbons containing a major quasicrystalline phase coexisting with an Al-matrix on a nanometer scale are pulverized by ball milling. The powders are consolidated by hot extrusion. Grain growth during consolidation causes the formation of a micrometer-scale microstructure. Mechanical alloying of leads to single-phase quasicrystalline powders. which are blended with different volume fractions of pure Al-powder and hot extruded forming (x = 40,50,60,80) micrometer-scale composites. Compression test data reveal a high yield strength of 700 MPa and a ductility of 5% for than the Al-Mn-Ce bulk samples. The strength level of the Al-Cu-Fe alloys is 550 MPa significantly lower. By the addition of different amounts of aluminum, the mechanical properties can be tuned to a wide range. Finally, a bulk metallic glass-forming Ti-Cu-Ni-Sn alloy with in situ formed composite microstructure prepared by both centrifugal and injection casting presents more than 6% plastic strain under compressive stress at room temperature. The in situ formed composite contains dendritic hcp Ti solid solution precipitates and a few -(Cu, Sn) grains dispersed in a glassy matrix. The composite micro- structure can avoid the development of the highly localized shear bands typical for the room temperature defor-mation of monolithic glasses. Instead, widely developed shear bands with evident protuberance are observed. resulting in significant yielding and homogeneous plastic deformation over the entire sample.
        4,800원
        17.
        2016.10 서비스 종료(열람 제한)
        Background : Invitro antioxidant activity, polyphenol and flavonoid aglycone contents in black and green tea products of balloon flower leaves were investigated to provide valuable information for the further development and utilization of resources of Platycodon grandiflorum. Methods and Results : Flavonoid aglycone contents were investigated using HPLC (SHIMADZU, Japan) with a hypersil ODS column (125 mm × 4 mm, 5-μm particle, HP). DPPH and ABTS radical scavenging activities were measured by method of Lee & Lee (2004) with slight modification. Antioxidant activity, polyphenol and flavonoid contents in green tea were significantly higher than these in black tea. PC analysis indicated that first principal components explained 79.9% of the total variability for five traits investigated. PC2 explained 19.7% of the variation. Conclusion : It can be concluded from these results that these characteristics can reveal the active compound variation of black and green tea products of balloon flower leaves. These results provide scientific evidence for the utilization of balloon flower leaves.