• 한국수소및신에너지학회논문집
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• 제28권4호
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• pp.331-337
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• 2017

Proton Exchange Membrane Water Electrolysis (PEMWE) is one of the most popular and widely used methods for hydrogen production. PEMWE contributes to eco-friendly system via its energy storage system application, hence making it environmentally friendly to use. However, its main drawback is contamination of proton exchange membrane during water electrolysis. Existing cation such as magnesium, calcium and the likes are the cause for membrane contamination. As a result, the cation contamination give rise to degradation of performance of electrolysis and the reverse electrolysis is effective method to remove cation.

• 한국수소및신에너지학회논문집
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• 제15권2호
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• pp.159-165
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• 2004

Fuel cell makes electricity through chemical reaction. Bipolar-plate distribute hydrogen, oxidation using channel geometry condensation of water vapor inside channels of bipolar-plates lowers efficiency of fuel cell. Usually high pressured gas supply is used to solve the water condensation problem with serpentine type channel geometry. In this study, a new channel geometry shows feasible to minimize lowering efficiency due to water condensation through numerical and experimental analysis.

• 설비공학논문집
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• 제24권3호
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• pp.265-270
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• 2012

A finned tube type heat exchange module has been proposed for a multi-burner water tube boiler. Fin density and length increase in streamwise direction to equalize the evaporation for each module, which makes it difficult to apply conventional bulk design procedure. The design program has been improved by updating data for every row of tubes along the flow. A numerical simulation has been also conducted to evaluate the effect of inlet conditions and validated with experiment. The heat transfer of the first row has been underpredicted by the conventional Zhukauskas correlation, since the acceleration of the flow due to the blockage is not fully inflected. The fin tip temperature is also underpredicted by Bessel solution, because of the interaction with neighboring fins.

• 태양에너지
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• 제5권2호
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• pp.35-45
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• 1985

A solar hot water storage tank was designed and constructed to examine the heat exchange performances on load side for the solar thermal storage in a single loop solar water heating system. In the tank helically coiled tube was immersed. The hot water was circulated from either top or bottom. The circulation flow rate was varied from 500 ml/min to 20,000 ml/min. The effect of flow rate was observed. The thermal performances according to the flow rate and flow direction were examined. The temperature distributions in the tank and inside of the tubes were plotted along the process of cooling.

• 한국항해항만학회:학술대회논문집
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• 한국항해항만학회 2002년도 춘계학술대회논문집
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• pp.205-218
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• 2002

Recently, the water pollution of coastal sea area including harbor, bay and inland sea has been very serious and it causes various environmental impacts. In this study, water flow system of Danghang Bay, which has the narrow and long topographical characteristics with the narrow bay mouth and its flow is influenced principally by the tidal current, is investigated experimentally and numerically. In order to understand the tidal system of Danghang Bay, harmonic analysis is performed based on measured tidal range and flow velocity In addition, numerical model for tidal exchange is developed considering conditions of Danghang Ray. Calculated results show good agreement with measurements. Lastly. based on the proposed numerical model, exchange ratio of seawater volume in Danghang Bay is predicted.

• 대한화학회지
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• 제37권9호
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• pp.820-825
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• 1993

새로운 HDBPDA 이온교환체, {(4,5) : (13,14)-dibenzo-6,9,12-trioxa-3,15,21-triazabicyclo[15.3.l]heneicosa-(1,17,19)(18,20,21) triene ion exchanger: HDBPDA ion exchanger}의 이온교환용량은 3.8 meq/g이었다. 그리고 이 이온교환체에 대한 알칼리 및 알칼리토금속 이온들의 분포계수를 물과, 여러 농도의 염산용액중에서 측정하였다. 금속이온들의 분포계수는 염산농도의 영향을 거의 받지 않았으나, 대체적으로 염산의 농도가 감소할수록 점진적으로 약간 증가하는 경향을 보였다. 그리고 물속에서의 분포계수가 가장 컸다. HDBPDA 이온교환체를 사용하여 알칼리 및 알칼리토금속 이온들을 컬럼이온교환크로마토그래피로 분리하였으며, 이때 용리액으로 물을 사용하였다. 또한 알칼리 및 알칼리토금속 이온들의 분포계수는 그들 이온들의 이온반경이 증가함에 따라 증가하였다.

• 대한가정학회지
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• 제17권1호
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• pp.22-28
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• 1979

The phyio-chemical properties of Ion exchange salt, crude salt, particaly refined salt, and Isoized salt were determined. The basic amount of salt used in cooking were standardized . Acceptabilities as to the taste and saltiness of food prepared with the standard amounts of various kinds of salt were compared. Whereupon, the following conclusion was obtained. 1) Crude salt showed 12.23 per cent water content, the highest among the kinds of salt examined, while particaly refined salt had 2.53% water content. Refined salt, Ion exchange salt, and Iodized salt showed 0.36%, and 0.28%, respectively. 2) Where the same amount of salt was dissolved in the same amount of water, crude salt and partialy refined salt were dissolved twice as Ion exchange salt of fine-grain form, refined salt, and Iodized salt. In actual cooking, Ion exchanges salt and refined salt are used only half as much as raw salt, and it can be said that the time required for dissolving salt is the same. 3) The comparison between content and weight of various kinds of salt showed that the weights of Ion exchange salt, Iodized salt, and refined salt were two times as heavy as crude salt and partialy refined condition of same content. 40 The threshold concentration of salt is the sensed degree of saltiness. Different concentrations were recorded for various for various kinds of salt, the threshold concentration of Ion exchanges salt showed the lowest degree of 0.05, while that of partialy refined salt was 0.09 equivalent to 1.8 times that of the former. 5) Experimental cooking involving various kinds of salt indicated that where salt was used accurately, soup, vegetables, kimchi, and soybean sauce which were prepared with Ion exchanges salt showed the best acceptability , but no statistical differences could be noted among sarious kinds of salt used in preparing those foods.

• 멤브레인
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• 제25권2호
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• pp.144-151
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• 2015

수용성 고분자인 poly(vinyl alcohol) (PVA)에 가교제인 sulfosuccinic acid (SSA)를 첨가하여 가교반응을 통해 물에 용해되지 않는 막을 제조하였으며, 이온교환능력을 부여하기 위해 poly(4-styrene sulfonic acid-co-maleic acid) (PSSA_MA)를 PVA 질량대비 70, 80, 90 wt%로 달리 첨가하여 막을 제조하였다. 제조한 막의 특성을 알아보기 위해 FT-IR, 함수율, 이온교환용량, 이온전도도, 메탄올 투과도를 측정하였다. 함수율과 이온교환용량, 이온전도도는 PSSA_MA 함량이 증가할수록 증가하는 경향을 나타내었으며 메탄올 투과도는 감소하는 경향을 나타내었다. 특성평가 결과 본 실험 막의 최적 조성은 PVA10/SSA9/PSSA_MA80으로 도출되었다.

• Nuclear Engineering and Technology
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• 제37권6호
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• pp.595-604
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• 2005

A new instrument, an average BDFT (Birectional Flow Tube), was proposed to measure the flow rate in single and two phase flows. Its working principle is similar to that of the Pilot tube, wherein the dynamic pressure is measured. In an average BDFT, the pressure measured at the front of the flow tube is equal to the total pressure, while that measured at the rear tube is slightly less than the static pressure of the flow field due to the suction effect downstream. The proposed instrument was tested in air/water vertical and horizontal test sections with an inner diameter of 0.08m. The tests were performed primarily in single phase water and air flow conditions to obtain the amplification factor(k) of the flow tube in the vertical and horizontal test sections. Tests were also performed in air/water vertical two phase flow conditions in which the flow regimes were bubbly, slug, and churn turbulent flows. In order to calculate the phasic mass flow rates from the measured differential pressure, the Chexal drift-flux correlation and a momentum exchange factor between the two phases were introduced. The test results show that the proposed instrument with a combination of the measured void fraction, Chexal drift-flux correlation, and Bosio & Malnes' momentum exchange model could predict the phasic mass flow rates within a $15\%$ error. A new momentum exchange model was also proposed from the present data and its implementation provides a $5\%$ improvement to the measured mass flow rate when compared to that with the Bosio & Malnes' model.

• 한국농공학회논문집
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• 제51권6호
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• pp.53-62
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• 2009

The EFDC (Environmental Fluid Dynamics Code), a numerical model for simulating three-dimensional (3D) flow, transport, and biogeochemical processes in surface water systems including rivers, reservoirs, and estuaries, was applied to assess the effect of sea water and fresh water exchange rates ($Q_e$) on the mixing characteristics of a conservative pollutant (tracer) induced from upstreams and salinity in Saemangeum Lake, Korea. The lake has been closed by a 33 km estuary embankment since last April of 2006, and now seawater enters the lake partially through two sluice gates (Sinsi and Garyuk), which is driving the changes of hydrodynamic and water quality properties of the lake. The EFDC was constructed and calibrated with surveyed bathymetry data and field data including water level, temperature, and salinity in 2008. The model showed good agreement with the field data and adequately replicated the spatial and temporal variations of the variables. The validated model was applied to simulated the tracer and salinity with two different gate operation scenarios: RUN-1 and RUN-2. RUN-1 is the case of real operation condition ($Q_e=25,000,000\;m^3$) of 2008, while RUN-2 assumed full open of Sinsi gate to increase $Q_e$ by $120,000,000\;m^3$. Statistical analysis of the simulation results indicate that mixing characteristics of pollutants from upstream can be significantly affected by the amount of $Q_e$.