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        검색결과 644

        181.
        2018.02 KCI 등재 구독 인증기관 무료, 개인회원 유료
        A theoretical model has been studied to describe the sound radiation analysis for a railway under the action of harmony line moving forces. When a railway is analyzed, it had been modeled as curved beams with distributed springs and dash-pots that represent the radial, tangential stiffness and damping of rail, respectively. The reaction due to fluid loading on the vibratory response of the curved beam is taken into account. The curved beam is assumed to occupy the plane y=0 and to be axially infinite. The curved beam material and elastic foundation are assumed to be lossless Bernoulli-Euler beam theory including a tension force(T), damping coefficient(C) and stiffness of foundation(Κ2) will be employed. The expression for sound power is integrated numerically and the results examined as a function of Mach number(M), wave-number ratio(γ) and stiffness factor(Ψ).
        4,000원
        196.
        2017.04 KCI 등재 구독 인증기관 무료, 개인회원 유료
        이 연구에서는 지표 관측 자료와 위성 자료 그리고 GWNU 단층 복사 모델을 이용하여 맑은 상태의 전천 일사 량을 계산하였으며, 전운량에 따라 관측 및 모델의 일사량 값을 비교 분석하였다. 연구 자료는 2012년 강릉원주대학교 복사 관측소의 전천 일사량, 기온, 기압, 습도, 에어로졸 등의 관측 자료와 OMI 센서의 오존전량 자료 그리고 구름의 유무 및 전운량을 판단하기 위하여 자동 전운량 장비인 Skyview 자료를 이용하였다. 전운량이 0 할인 맑은 날의 경우 관측 값과 모델 값이 0.98로 높은 상관계수를 나타내었으나 RMSE가 36.62Wm−2로 비교적 높게 나타났다. 이는 Skyview 장비가 얇은 구름이나 박무 및 연무 등의 기상상태를 판단하지 못하였기 때문이다. 흐린 날의 경우 구름의 영 향을 보정하기 위해 전운량과 두 값의 차에 대한 비율을 이용한 회귀식을 복사 모델에 적용하였으며, 장비의 오탐지를 제외한 경우 상관계수가 0.92로 높은 상관성을 보였으나 RMSE가 99.50 Wm−2으로 높은 값을 보였다. 더 정확한 분석 을 위해서는 직달 성분의 차폐 유무 및 구름 광학 두께를 포함한 다양한 구름 요소의 추가적인 분석이 요구된다. 이 연구결과는 분 또는 시간에 따른 일사량을 산출하여 일사량이 관측되지 않는 지역에서 유용하게 사용될 수 있다.
        4,300원
        197.
        2017.03 KCI 등재 구독 인증기관 무료, 개인회원 유료
        This study was conducted to investigate the effect of ultraviolet light (UV-B) on plant growth and petal antioxidants of edible flower pansy (Viola × wittrochiana ‘Rose’ and ‘Yellow’, V. cornuta ‘Purple’). The plants were grown under white LED of 100 μmol·m-2·s-1 PPFD and treated by UV-B of 10, 20 and 30 minutes per day: UVB-10, UVB-20, and UVB-30 respectively. The plant growth was significantly inhibited as longer UV-B radiation exposure, even ‘Rose’ could not f lower under UVB-30. NPQ increase was observed in all cultivars with longer UV-B irradiation exposure. Also, anthocyanin in ‘purple’ and ‘Rose’ or carotenoid in ‘Yellow’ increased in the petals as longer UV-B radiation exposure. Unexpectedly the contents of total phenol and DPPH did not show the significance in UV-B treatments. In conclusion, the applicable UVB exposure to edible pansy in order to more accumulate antioxidants in petals would be in 20 minutes per day.
        4,000원
        198.
        2017.03 KCI 등재 구독 인증기관 무료, 개인회원 유료
        The seaweed Ecklonia cava, a brown algae abundant in JeJu Island, South Korea, has large amounts of the polyphenol compound phloroglucinol (PG, 1,3,5-trihydroxybenzene), which has been proposed to exert interesting biological properties including antioxidant and radioprotective effects against ionizing radiation-induced damages in various cells and tissues. To identify antioxidant and radioprotective effects of PG in skin tissues, we exposed mice to 8.5 Gy whole body irradiation (WBI) at day 6 after depilation with and without PG treatment. In PG treated cases, PG was applied twice, once at 17.8 hours before and then at the time of WBI. At 8 hours after WBI, a reduction in the formation of thiobarbituric acid-reactive substrates (TBARS) was observed in the PG treated group. Upon western blot analysis, PG treatment overexpressed the MnSOD, catalase, and GPx-1, although the difference was not significant. In parallel with the results of western blot analysis, the percentage of MnSOD-and catalase-positive cells was significantly increased at 8 and 24 hours after WBI, while no significant difference was observed over 48 hours in PG treated skins. Moreover, PG treatment increased the percentage of Ki-67 positive cells compared with that of irradiated only mice at 8 hours after WBI. Our results suggest that PG is effective at attenuating oxidative stress, and that the promotion of antioxidant enzymes such as MnSOD and catalase may be an important aspect for its radioprotection in skin.
        4,300원
        199.
        2016.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Free radicals originate due to the radiolysis of cytoplasmic water with low “Linear Energy Transfer” (LET) radiations. Naringenin (Ng) is a natural antioxidative compound found in citrus fruits. This study revealed that Naringenin (Ng) reduced the radiation damage of critical organs by scavenging oxidative free radicals. In the study, Ng was orally administrated to rats daily for 7 consecutive days, prior to whole body exposure to gamma-rays. The scavenging efficacy was evaluated biochemically by measuring the concentration of cytotoxic byproducts and the activity of enzymes relevant to oxidative free radicals, after extracting the organs from the exposed rat. We observed increased levels of malondialdehyde (MDA) concentration, and decrease in the activities of superoxide dismutase (SOD) and catalase (CAT) in the exposed control group. However, pretreatment with Ng significantly reduced the MDA concentration, and increased the activities of SOD and CAT, as compared to the control group, due to the free radical scavenging by Ng. The results indicate that Ng administration prior to irradiation could protect critical organs from radiation damage.
        4,000원
        200.
        2016.11 구독 인증기관·개인회원 무료
        Salined water electrolysis is one of representative commercial processes to produce valued chemicals such as chlorine, hydrogen. The most important issue in the electrolysis is to reduce energy consumption. A plausible solution is to accelerate Na+ion transport through cation exchange membranes and to reduce interfacial resistance with electrodes. The conventional membrane materials are based on PFSAs such as Nafion®. In spite of their robust chemical resistance, there are several critical demerits including expensive production cost and difficult tuning capability. For this, a SPAES random copolymer-silica nanocomposite is used as a membrane matrix with a high ionic conductivity and radiation-grafted with a highly sulfonated poly(strylene) to provide a branched polymer architecture for improved interfacial characteristics.