• Title/Summary/Keyword: 물의 순환

Search Result 2,166, Processing Time 0.025 seconds

Policy for Water Cycle of Agricultural Reservoirs Considering Downstream - Focused on HRT of Agricultural Reservoir in Chungcheongnam-do and Daejeon Metropolitan City - (하천(河川)을 고려한 호소(湖沼)의 물 순환 정책방안 -충남·대전지역 농업용 호소의 체류시간을 중심으로-)

  • Yi, Sang-Jin
    • The Journal of the Korea Contents Association
    • /
    • v.11 no.9
    • /
    • pp.246-253
    • /
    • 2011

  • Several problems occurred due to the use of the wrong water cycle system in the watershed. This was caused by a dry stream in the lower parts of the tributaries and the deterioration in value of usage by water pollution in accordance with water storage. This was maintained for a long period of time in the reservoir which secured the agricultural water. As a result of the operational status in the agricultural reservoirs focused on Chungcheongnam-do and Daejeon metropolitan city, a dry stream appeared because hydraulic retention time(HRT) in the majority of reservoirs was maintained for 8 months of the year. The water quality in the agricultural reservoir was fairly related to the water cycle system due to rainfall and input of pollutants from the population and livestock in the watershed. Consequently, the storage water volume and the time period of the water in the reservoir should be controlled by the reduction of the pollution load in the water and the prevention of a dry stream. Also, the water cycle system in the watershed should be improved by maintaining a short HRT of the reservoir.

  • https://doi.org/10.5392/JKCA.2011.11.9.246 인용 PDF KSCI

Effect of Hydrogen Recirculation on the Performance of Polymer Electrolyte Membrane Fuel Cell with Dead Ended Mode (Dead ended 모드에서 수소 재순환이 고분자전해질연료전지의 성능에 미치는 영향)

  • Kim, Junseob;Kim, Junbom
    • Korean Chemical Engineering Research
    • /
    • v.57 no.4
    • /
    • pp.531-538
    • /
    • 2019

  • As the performance of PEMFC has been improved, the water and heat generated by reaction have increased so, the water and heat management of PEMFC is becoming more important. In this study, hydrogen recirculation was applied as the water management technique and the effect of recirculation flow rate, purge interval and duration on the performance of PEMFC was investigated. Anode pressure, fuel humidity and utilization, water discharge amount was measured to check the effect of purge conditions on performance. As the recirculation flow rate has increased, the performance of PEMFC became lower due to decrease of anode outlet pressure. According to the purge conditions, instantaneous voltage drop has occurred because of accumulated water. In frequent purge conditions, the performance of PEMFC gradually decreased due to fuel humidity control failure. Stable performance and high fuel utilization was achieved on this work by analyzing the effect of purge conditions.

  • https://doi.org/10.9713/kcer.2019.57.4.531 인용 PDF KSCI HTML

Wind-Driven Circulation Using a Curvilinear Hydrodynamic Three-Dimensional Model (곡선형격자 삼차원 수치모형을 이용한 바람에 의한 물의 순환)

  • Lee, Hye-Keun
    • Journal of Korean Society of Coastal and Ocean Engineers
    • /
    • v.6 no.1
    • /
    • pp.1-11
    • /
    • 1994

  • A curvilinear hydrodynamic three-dimensional model is presented for the study of wind-driven circulation in a shallow lake. Numerical results are compared with field data. Thermal stratification effects were found to be critical to the successful simulation of circulation under increasing winds. When there ate insufficient meteorological data, the so-called inverse method can be used for the estimation of heat flux.

  • PDF