• 제목/요약/키워드: adverse effect

검색결과 2,341건 처리시간 0.031초

공력에 의한 HEMU-400x 고속열차의 주행안정성 평가 (Stability Evaluation on Aerodynamics of High Speed Railway Train)

  • 최지훈;박태원;심경석;곽민호;이동호
    • 한국소음진동공학회논문집
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    • 제22권3호
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    • pp.244-252
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    • 2012
  • Recently, the speed of a train has been increased. So the trains are being exposed to wind more severely than before. Because of the operation of high speed trains and lightweight of the train, risks of train derailment have being increased. In this study, aerodynamic effects of a newly designed high speed train, HEMU-400x, are evaluated. For aerodynamic effect evaluation, analysis method is selected by examining the safety standards for high speed train. The condition of aerodynamic effects is selected by adverse effect conditions. In order to calculate $C_s$ coefficients, numerical analysis is conducted. Using $C_s$ coefficients, the side force is calculated. Through dynamics analysis, derailment and wheel unloading are obtained. Using these results, derailment evaluation is performed.

전기자동차 보급 전망에 따른 배전계통에서의 영향 평가 (Influence Evaluation of Electric Vehicle Load on Distribution Systems by the penetration rate of Electric Vehicle)

  • 김철우;한승호;송택호;정문규
    • 대한전기학회:학술대회논문집
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    • 대한전기학회 2011년도 제42회 하계학술대회
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    • pp.256-257
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    • 2011
  • The development for Eco-friendly cars has been expanded as the concern about environmental pollution and a rise in gas prices. The Electric Vehicle(EV) and Plug in Hybrid Electric Vehicle(PHEV) are generally connected on distribution power systems to charge the traction batteries. The growing number of EV/PHEVs could have a effect on distribution power systems and result in overload of power utilities and power quality problems. In order to reduce the adverse effect on distribution power systems, the influence of electric vehicle loads should be evaluated. In this paper, the influence of electric vehicle loads is evaluated by using OpenDSS(Open Source Distribution System Simulator) according to the penetration rate of electric vehicle.

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열 및 열-기계적 피로에 의한 내열합금 표면의 홈의 형상변화 (Morphological Change of the Surface Groove on a Heat Resistant Alloy Due to Thermal and Thermo-Mechanical Cycling)

  • 이봉훈;선신규;강기주
    • 대한기계학회:학술대회논문집
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    • 대한기계학회 2007년도 춘계학술대회A
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    • pp.11-16
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    • 2007
  • The existence of grooves on the surface of bond coat has significant effect on the instability of thermal barrier system. In this work, the thermal-mechanical fatigue experiments were performed under various thermal and mechanical loads for FeCralloy specimens with and without yttrium dopant to observe the deformation of surface grooves. The effect of temperature, fatigue load and the ratio of curvature on the deformation of grooves were investigated. As the results, it has been found that the higher load level and the higher curvature ratio induces the larger deformation near the grooves. However, the addition of yittrium dopant induces the adverse results.

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Active vibration control of smart composite structures in hygrothermal environment

  • Mahato, P.K.;Maiti, D.K.
    • Structural Engineering and Mechanics
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    • 제44권2호
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    • pp.127-138
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    • 2012
  • The composite materials may be exposed to environmental (thermal or hygral or both) condition during their service life. The effect of environmental condition is usually adverse from the point of view of design of composite structures. In the present research study the effect of hygrothermal condition on the design of laminated composite structures is investigated. The active fiber composite (AFC) which may be utilized as actuator or sensor is considered in the present analysis. The sensor layer is used to sense the level of response of the composite structures. The sensed voltage is fed back to the actuator through the controller. In this study both displacement and velocity feedback controllers are employed to reduce the response of the composite laminate within acceptable limit. The Newmark direct time integration scheme is employed along with modal superposition method to improve the computational efficiency. It is observed from the numerical study that the laminated composite structures become weak in the presence of hygrothermal load. The response of the structure can be brought to the acceptable level once the AFC layer is activated through the feedback loop.

Synthesis of Epoxy Functional Siloxane and its Effect on Thermal Stress

  • Hyun, Dae-Sup;Jeong, Noh-Hee
    • 한국응용과학기술학회지
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    • 제26권4호
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    • pp.379-384
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    • 2009
  • Epoxy resin based encapsulants are widely used in semiconductor packaging applications. Epoxy resin based encapsulants are often subject to crack or delamination during the reliability test due to the thermal stress caused by high modulus nature of epoxy resins. Epoxy functional siloxanes are often added into epoxy resin to reduce the modulus so that the thermal stress can be reduced. Epoxy functional siloxanes, additives for reduced modulus, were synthesized and added into the curable epoxy resins. The modulus and the coefficient of thermal expansion (CTE) were also measured to investigate the thermal stress and to see whether the epoxy functional siloxane adversely affects the CTE or not. As a result, around 26% to 72% of thermal stress reduction was observed with no adverse effect on CTE.

가솔린첨가제 MTBE의 인체 및 생태영향 (Effects of Gasoline Additive, Methyl tert-Butyl Ether (MTBE) to Human Health and Ecosystem)

  • 안윤주;이우미
    • Environmental Analysis Health and Toxicology
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    • 제21권2호
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    • pp.93-102
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    • 2006
  • Methyl tert-butyl ether (MTBE), an octane booster that is added to the reformulated gasoline, has been a widespread contaminant in aquatic ecosystem. MTBE is a recalcitrant pollutant having low biodegradability. Due to its higher water solubility and low octanol-water partition coefficient, it can be rapidly transported to the surrounding water environment. Also, MTBE is a known animal carcinogen, and is classified as a possible human carcinogen by U. S. Environmental Protection Agency. The adverse effect of MTBE to aquatic biota was widely reported. In Korea, the recent detection of MTBE in groundwater near gasoline filling stations has drawn concern to public health and ecosystem. To address this concern, the effect of MTBE to human health and ecosystem was discussed in this review. Also, ecotoxicity data of MTBE for fish, invertebrates, and algae were extensively compared to estimate the hazard concentration 5($HC_5$) of MTBE as a screening level.

Synergistic effect of a mixed herbal extract on bone loss in ovariectomized (OVX) rats

  • Ha , Hye-Kyung;Lee, Je-Hyun;Lee, Han-Gu;Song, Kye-Yong;Kim, Chung-Sook
    • 대한약학회:학술대회논문집
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    • 대한약학회 2002년도 Proceedings of the Convention of the Pharmaceutical Society of Korea Vol.2
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    • pp.385.3-386
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    • 2002
  • Current therapeutics for osteoporosis are often associated with adverse effects with long-term use. The purpose of this study was to find out herbal drug interaction and to apply an alternative drug candidate for osteoporosis based on a traditional medicinal herb that may have fewer side effects and less uterine hypertrophy. Effect of 219-H. a mixed herbal extract including Astragali Radix. was investigated on osteoporosis in vitro and in vivo models. (omitted)

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Effect of Certain Insecticides in Controlling Pesudodendrothrips mori in Mulberry

  • Misra, Sunil;Reddy, C.Rajagopal;Sivaprasad, V.;Reddy, K.Dharma;Chandrashekhariah
    • International Journal of Industrial Entomology and Biomaterials
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    • 제7권1호
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    • pp.83-86
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    • 2003
  • Mulberry plantations are prone to several kinds of insect pests including the thrips, Pesudodendrothrips mori. The thrips infestation affects the qualitative and quantitative characters of mulberry leaf, which in turn affects the silkworm cocoon crop. In the present study, four commercial insecticides viz., Rogor, Quinalphos, Confidor and Methyl parathion were tested for their efficacy in the control of P. mori thrips. These insecticides were observed to kill 68-80% within 24 hrs in vivo and 100% after 12 hrs post-treatment in vitro. Confidor (0.05%) and Quinalphos (0.2%) were most effective in controlling the thrips incidence. The insecticide-sprayed mulberry leaves did not show any adverse effect on the rearing of silkworms.

The effect of the dissolved oxygen concentration on the production of manganese peroxidase by Phaenerochaete chrysosporium

  • 최수형;구만복
    • 한국생물공학회:학술대회논문집
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    • 한국생물공학회 2000년도 추계학술발표대회 및 bio-venture fair
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    • pp.171-174
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    • 2000
  • 본 연구는 용존산소의 양에 따른 MnP의 생산양상을 체계적으로 연구하였으며, 과량의 산소 공급 시 MnP 생산이 저해될 수 있음을 산소공급에 따른 과량의 $H_2O_2$생산 측면에서 설명하고 있다. 또한 보다 높은 MnP 생산을 위한 산소공급방법을 제시하고자 하였다.

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Antioxidant effect of myricetin with other antioxidants, taurine and $\beta$-carotene on mouse melanoma cell

  • Yu, Ji-Sun;Kim, An-Keun
    • 한국응용약물학회:학술대회논문집
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    • 한국응용약물학회 2003년도 Annual Meeting of KSAP : International Symposium on Pharmaceutical and Biomedical Sciences on Obesity
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    • pp.69-69
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    • 2003
  • There are now increasing evidences that free radicals and reactive oxygen species are involved in a variety of pathological events. Reactive Oxygen Species (ROS) are produced during normal cellular function. ROS lead to lipid peroxidation, massive protein oxdiation and degradation. Under normal conditions, antioxidant are substnaces that either directly or indirectly protect cell against adverse effect of ROS. several biologically important compound include ${\beta}$-carotene, taruine and flavonoids reported have antioxidant function. The various antioxidant either scavange superoxide and free radicals or stimulate the detoxification mechanisms within cells resulting in increased detoxification of free radicals formation and thus in prevention of many pathophysiologic processes. This study carried out to investigate the antioxidant activity of flavonoids, myricetin with other antioxidants, ${\beta}$-carotene and taurine on B16Fl0. In order to investigate the efficacy of antioxidant activity, we measured cell viability, antioxidant enzyme activity (SOD, GPX, CAT) and intracellular reactive oxygen intermediate (ROI). In this results, we show that these flavonoids with other antioxidant substrates are increased antioxidant activity level.

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