• 제목/요약/키워드: Air to water

검색결과 6,150건 처리시간 0.036초

조간대에서 조위에 따른 기온과 수온 변화 : 여수 오도섬 (Variations in Air Temperature and Water Temperature with Tide at the Intertidal Zone : Odo Island, Yeosu)

  • 조원기;강동환;김병우
    • 한국환경과학회지
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    • 제31권12호
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    • pp.1027-1038
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    • 2022
  • The intertidal zone has both land and marine characteristics and shows complex weather environments. These characteristics are suited for studying climate change, energy balance and ecosystems, and may play an important role in coastal and marine weather prediction and analysis. This study was conducted at Odo Island, approximately 300m from the mainland in Yeosu. We built a weather observation system capable of real-time monitoring on the mud flat in the intertidal zone and measured actual weather and marine data. Weather observation was conducted from April to June 2022. The results showed changes in air temperature and water temperature with changes in the tide level during spring. Correlation analysis revealed characteristic changes in air temperature and water temperature during the day and night, and with inundation and exposure.

기후변화 시나리오별 한강유역의 수계별 수온상승 가능성 (Potential Impacts of Climate Change on Water Temperature of the Streams in Han-River Basin)

  • 김민희;이정희;성경희;임철수;황원재;현승훈
    • 한국물환경학회지
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    • 제38권1호
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    • pp.19-30
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    • 2022
  • Climate change has increased the average air temperature. Rising air temperature are absorbed by water bodies, leading to increasing water temperature. Increased water temperature will cause eutrophication and excess algal growth, which will reduce water quality. In this study, long-term trends of air and water temperatures in the Han-river basin over the period of 1997-2020 were discussed to assess the impacts of climate change. Future (~2100s) levels of air temperature were predicted based on the climate change scenarios (Representative concentration pathway (RCP) 2.6, 4.5, 6.0, and 8.5). The results showed that air and water temperatures rose at an average rate of 0.027℃ year-1 and 0.038℃ year-1 respectively, over the past 24 years (1997 to 2020). Future air temperatures under RCP 2.6, 4.5, 6.0, and 8.5 increased up to 0.32℃ 1.18℃, 2.14℃, and 3.51℃, respectively. An increasing water temperature could dissolve more minerals from the surrounding rock and will therefore have a higher electrical conductivity. It is the opposite when considering a gas, such as oxygen, dissolved in the water. Water temperature also governs the kinds of organisms that can live in rivers and lakes. Fish, insects, zooplankton, phytoplankton, and other aquatic species all have a preferred temperature range. As temperatures get too far above or below this preferred range, the number of individuals of the species decreases until finally there are none. Therefore, changes of water temperature that are induced by climate change have important implications on water supplies, water quality, and aquatic ecosystems of a watershed.

상수도관의 물 흐름 방향을 고려한 공기주입 세척 및 단방향 플러싱 공법의 세척 효과 비교 연구 (Comparative study on cleaning effects of air scouring and unidirectional flushing considering water flow direction of water pipes)

  • 서지원;이규상;김기범;형진석;김태현;구자용
    • 상하수도학회지
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    • 제33권5호
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    • pp.353-366
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    • 2019
  • This research proposes an optimal flushing operation technique in an effort to prevent secondary water pollutions and accidents in aged pipes, and to improve the cleaning effect of unidirectional flushing. Water flow directions were analyzed using EPANET 2.0, while flushing and air scouring experiments in forward and reverse directions were performed in the field. In 42 experiments, average residual chlorine concentration and turbidity were improved after cleaning compared to before cleaning. It was found that even when the same cleaning method was used, further improvement of cleaning effect was possible by applying air injection and reverse direction cleaning techniques. By means of one-way ANOVA(Analysis of variance), it was also possible to statistically verify the need of actively utilizing air injection and reverse direction cleaning. Based on correlation between turbidity and TSS, the total amount of suspended solids removal was estimated for 874 flushing operations and 194 air scouring operations. The result showed that air scouring used more discharge water than flushing by an average of $4.9m^3$ yet with larger amounts of suspended solids removal by an average of 145.9 g. The result of analysis on turbidity values from 887 flushing operations showed low cleaning effect of unidirectional flushing for the pipes with diameters over 300 mm. In addition, the turbidity values measured during cleaning showed an increasing tendency as pipe age increased. The methodology and results of this research are expected to contribute to the efficient maintenance and improvement of water quality in water distribution networks. Follow-up research involving the measurement of water quality at regular time intervals during cleaning would allow a more accurate comparison of discharge water quality characteristics and cleaning effects between different cleaning methods. To this end, it is considered necessary to develop a standardized manual that can be used in the field and to provide relevant trainings.

전자빔을 이용한 흐름반응기에서의 Trichloroethylene/Air 분해 (Decomposition of Trchloroethylene/Air Mixture by Electron Beam Irradiation in a Flow Reactor)

  • 원양수;한도홍;박완식;;이홍승
    • 한국대기환경학회지
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    • 제17권1호
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    • pp.97-104
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    • 2001
  • Decomposition of trichloroethlyene(TCE) in electron beam irradiation was examined on order to obtain information on the treatment of VOC in air. Air containing vaporized TCE has been studied in a flow reactor with different reaction environments, at various initial TCE concentration and in the presence and absence of water vapor. Maximum decomposition was observed in oxygen reaction environment and the degree of decomposition was about 99% at 20kGy for 2,000ppm initial TCE. The concentration of TCE exponentially decreased with dose in air and pure oxygen. The effect of water vapor on TCE decomposition efficiency was examined. The decomposition rate of TCE in the presence of water vapor (5,600 ppm) was approximately 10% higher than that in the absence of water vapor. Dichloroacetic acid, dichloroacethyl chloride and dichloroethyl ester acid were identified as primary products of this reaction adn were decomposed and oxidized to yield CO and $CO_2$. Perchloroethylene, hexachloroethane, chloroform and carbon tetrachloride were also observed as highly chlorinat-ed by products.

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충진층식 세정집진기의 집진특성 실험 (An Experiment on the Particle Collection Characteristics in a Packed Wet Scrubber)

  • 유경훈;노희환;최은수;김종균
    • 설비공학논문집
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    • 제15권4호
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    • pp.305-311
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    • 2003
  • DOP aerosol particles with geometric mean diameter of 0.5-3.0 ${\mu}{\textrm}{m}$, geometric standard deviation of 1.1-1.3 and total number concentration of 1,500-8,000 Particles/㎤ were used to determine collection efficiencies of a packed wet scrubber with respect to particle size. The tested operating variables included air velocity and water injection rate. It was shown from the experimental results that the collection efficiencies increased with increasing water injection rate and decreasing air velocity. Meanwhile, as for the particle size variation, all of the collection efficiency curves increased rapidly between 0.57-1.41${\mu}{\textrm}{m}$ for the range of water injection rate above 30 L/min. It was also seen that the collection efficiency of a packed wet scrubber is mainly governed by the mechanism of inertial impaction.

Study of Flooding Prevention on Cathode Gas Diffusion Layer for Dynamic Load Fuel Cell

  • Choi, Dong-Won;You, Jin-Kwang;Rokhman, Fatkhur;Bakhtiar, Agung;Choi, Kwang-Hwan
    • 한국태양에너지학회:학술대회논문집
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    • 한국태양에너지학회 2011년도 추계학술발표대회 논문집
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    • pp.270-273
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    • 2011
  • Water management is important in proton exchange membrane fuel cell because the water balance has a significant impact on the overall fuel cell system performance. In fuel cell vehicle, the vehicle's power demand is dynamic; therefore, the dynamic water management system is required. This present study proposes a method to control the humidity of the input air in cathode side of the fuel cell vehicle. The simulation using several driving cycles shows the proposed air humidification control obtains a relatively good result. The liquid saturation level is seen constant at the target level although still there are small deviations at driving cycles which having averagely high power demands.

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녹지 조건에 따른 최고기온의 비교연구 (Comparative Study of Maximum Temperature Condition in Green Space)

  • 윤용한
    • 아시안잔디학회지
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    • 제15권4호
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    • pp.181-186
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    • 2001
  • 본 연구는 토지피복현황과 수림형태 등이 다양한 도시녹지를 대상으로 기온저감효과와의 관련성을 파악한 결과 아래와 같은 효과가 실증되었다. 그 결과를 바탕으로 녹지 내의 토지피복현황과 기온분포, 토지피복비율 및 녹적량과 기온 저감효과와의 관련성을 회귀분석 등에 의해 해석하였다. 그 결과, 포장면과 나지 주변에서는 고온역이, 수림지와 수면 주변에서는 저온역이 형성되었다. 특히, 교목+소교목층으로 피복되어 있는 구역과 수림으로 둘러싸인 수면, 소하천 주변에는 상대적으로 낮은 기온이었다. 또한, 저온을 형성하는 메커니즘은 토지피복비율(수림지, 초지, 수면)등이고, 그 토지피복의 종류와 비율에 따라 기온저감효과가 서로 달랐다. 더욱이 녹정량과 기온과의 관계는 부의 상관을 나타냈고, 그 효과는 교목, 소교목, 관목의 순이다.

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에너지플러스 시뮬레이션을 통한 하천수 열원 히트펌프 시스템의 적용 가능성 분석 (An Applicability Analysis of River Water Source Heat Pump System using EnergyPlus Simulation)

  • 손병후
    • 한국지열·수열에너지학회논문집
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    • 제18권2호
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    • pp.10-21
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    • 2022
  • A water source heat pump (WSHP) system is regarded as an energy-efficiency heating and cooling supply system for buildings due to its high energy efficiency and low greenhouse gas emissions. Recently, water sources such as river water, lake water, and raw water are attracting attention as heat sources for a heat pump system in Korea. This paper analyzed the applicability of a river water source heat pump system (RSHP). The river water temperature level was compared with the outdoor air and ground temperature levels to present applicability. In addition, the cooling and heating performance were compared through a simulation approach for the RSHP and a ground source heat pump (GSHP) applied to a large-scale office building. To compare the temperature level, the actual data were applied to the river water and the outdoor air, while the simulation results were applied to the ground circulation water. The results showed that the change in river water temperature throughout the year was similar to the change in outdoor air temperature. However, unlike the outdoor air temperature, the difference between the hourly and daily average river water temperatures was not large. The temperature level of river water was lower during the heating season and somewhat higher during the cooling season than that of the ground circulation water. Finally, the performance of the RSHP system was 13.4% lower than that of the GSHP system on an annual-based.

무기질 폴리머계 흡수방지재를 도포한 모르터의 발수성능 평가에 관한 실험적 연구 (An Experimental Study on the Water Repellent Property of Mortar Applied Water Repellent Agent of Inorganic Polymer Type)

  • 이일형;엄덕준;오상근
    • 한국건축시공학회:학술대회논문집
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    • 한국건축시공학회 2004년도 학술.기술논문발표회
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    • pp.33-37
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    • 2004
  • Recently, Growing tendency for structure surface to use water repellent agent has increased steadily. But investigation of it's protection and durability property is not sufficient. Therefore, this paper shows the investigation about repellent property and micro structure's change in surface layer of mortar that is applied by water repellent agent. Water repellent property, absorption coefficient, air permeability, porosity and observation of micro construct was investigated according to water repellent agent type. The test results indicated that mortar applied water repellent agent appears tiny absorption coefficient, but air permeability is maintained. The reason is because silane solution is coating at capillary surface of a wall and minute pore structure is changeless.

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액적충돌침식으로 인한 배관감육 예측체계 구축에 관한 연구 (A Study on the Development of Prediction System for Pipe Wall Thinning Caused by Liquid Droplet Impingement Erosion)

  • 김경훈;조연수;황경모
    • Corrosion Science and Technology
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    • 제12권3호
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    • pp.125-131
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    • 2013
  • The most common pipe wall thinning degradation mechanisms that can occur in the steam and feedwater systems are FAC (Flow Acceleration Corrosion), cavitation, flashing, and LDIE (Liquid Droplet Impingement Erosion). Among those degradation mechanisms, FAC has been investigated by many laboratories and industries. Cavitation and flashing are also protected on the piping design phase. LDIE has mainly investigated in aviation industry and turbine blade manufactures. On the other hand, LDIE has been little studied in NPP (Nuclear Power Plant) industry. This paper presents the development of prediction system for pipe wall thinning caused by LDIE in terms of erosion rate based on air-water ratio and material. Experiment is conducted in 3 cases of air-water ratio 0.79, 1.00, and 1.72 using the three types of the materials of A106B, SS400, and A6061. The main control parameter is the air-water ratio which is defined as the volumetric ratio of water to air (0.79, 1.00, 1.72). The experiments were performed for 15 days, and the surface morphology and hardness of the materials were examined for every 5 days. Since the spraying velocity (v) of liquid droplets and their contact area ($A_c$) on specimens are changed according to the air-water ratio, we analyzed the behavior of LDIE for the materials. Finally, the prediction equations(i.e. erosion rate) for LDIE of the materials were determined in the range of the air-water ratio from 0 to 2%.