• 대한가정학회지
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• 제35권3호
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• pp.115-124
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• 1997

In this study, Water Repellent Finish was carried out before dyeing on cotton fabrics. It was aimed to improve on dyeing properties of cotton fabrics with direct dye. The results obtained were summerized as follows: 1. The K/S value of water repellent finished cotton fabrics increased. This phenomena in water repellent finished cotton fabrics were much more noticiable than unfinished cotton fabrics. 2. The color fastness(light, washing, and rubbing) of water repellent finished cotton-dyed were worse than those of unfinished cotton-dyed with direct dye. △E of water repellent finished cotton fabrics wasn't showed significant difference as compared with that of unfinished cotton fabrics. 3. The water repellency of finished cotton after dyeing got down from 100 to 70. That of finished-cotton before dyeing was 100. 4. Moisture regain, stiffness and weight of finished cotton fabrics were not almost differenciated with unfinished cotton fabrics. Moreover, the tensile strength of finished cotton fabrics was increased compared to that of unfinished cotton fabrics. As conclusion, according to the above results when the cotton fabrics were dyed with direct dye, it was much more effective that water repellent finished cotton fabrics were dyed rather than trational process, that is pre-dyeing after-finishing even if, by low liquor ratio. The physical properties of fabrics were maintained or increased.

• 수도
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• 제24권3호통권84호
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• pp.4-102
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• 1997

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2009년도 춘계학술대회 논문집
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• pp.319-322
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• 2009

This paper investigated environmental effects for passive, air-breathing, and vapor-feeding direct methanol fuel cells. In these experiments, experimental parameters are temperature($30^{\circ}C$, $40^{\circ}C$ and relative humidity(25%, 50%, 75%). From these experimental results, the water contents play a key role in terms of optimal ionic conductivity at the cathode catalyst layer. In case of pure methanol feeding, the performance is inversely proportional to the relative humidity. The water generation resulting from methanol crossover maintains ionic conductivity at the cathode. On the contrary, diluted methanol solution (50wt.%) lowers methanol crossover to the cathode. In order to increase ionic conductivity, the relatively high humidity is required to the cathode catalyst layer for the water generation. The relative humidity scales with the performance.

• Geomechanics and Engineering
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• 제14권2호
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• pp.187-193
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• 2018

Water inrush through the destruction of water resisting rock mass structure was divided into direct water inrush, key block water inrush and splitting water inrush. In the direct water inrush, the Reynolds numbers has a significant effect on the distribution of the water flow and vortex occurred in the large Reynolds numbers. The permeability coefficient of the fracture is much larger than the rock, and the difference is between 104 and 107 times. The traditional theory and methods are not considering the effect of inertia force. In the position of the cross fracture, the distribution of water flow can only be linearly distributed according to the fracture opening degree. With the increase of Reynolds number, the relationship between water flow distribution and fracture opening is studied by Semtex.

• 자원ㆍ환경경제연구
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• 제33권2호
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• pp.159-178
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• 2024

본 연구는 동태적 접근 방식을 이용하여, 지방 재정지출이 수질개선에 미치는 직접효과와 간접효과를 추정한다. 이를 위해 2010년부터 2018년까지 173개 시군구를 대상으로 패널자료를 구축하고, 2단계 동태패널모형을 추정한다. 실증분석 결과를 정리하면, 첫째, 수질 환경부문의 재정지출은 BOD 및 T-P 개선에 효과적인 것으로 나타났다. BOD에 비해 T-P에 대한 직접효과가 더 크게 나타났으며, 장기적으로 그 효과가 커지는 것으로 나타났다. 둘째, 수질개선을 위한 재정지출은 지역 소득에 긍정적인 영향을 미치는 것으로 나타났으며, 지역 소득과 BOD는 '역 U자형' 관계를 보였다. 수질 개선에 대한 재정지출의 평균적인 간접효과는 BOD에 대해서만 지역 경제성장 과정에서 수질을 악화시키는 것으로 나타났다. 셋째, BOD의 경우 수질개선에 대한 지방 재정지출 효과는 간접효과보다 직접효과가 컸으나, T-P의 경우 간접효과는 유의하지 않고, 직접효과에 의해서만 총효과가 결정되었다. 즉 지방 재정지출이 지역 경제성장을 통해 수질을 악화시킬 수 있지만, 수질을 직접적으로 개선하는 효과가 장·단기에 더욱 크게 나타났다.

• 상하수도학회지
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• 제25권3호
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• pp.399-405
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• 2011

In a desalination technology using RO membranes, chemical cleaning makes damage for membrane surface and membrane life be shortened. In this research cleaning technology using direct osmosis (DO) was introduced to apply it under the condition of high pH and high concentration of feed. When the high concentration of feed is injected to the concentrate side after release of operating pressure, then backward flow occurred from treated water toward concentrated for osmotic pressure. This flow reduces fouling on the membrane surface. Namely, flux of DO was monitored under pH 3, 5, 10 and 12 conditions at feed concentrations of NaCl 40,000 mg/L, 120,000 mg/L and 160,000 mg/L. As a result, DO flux in pH 12 increased about 21% than pH 3. DO cleaning was performed under the concentrate NaCl 160,000 mg/L of pH 12 during 20 minutes. Three kinds of synthetic feed water were used as concentrates. They consisted of organic, inorganic and seawater; chemicals of SiO2 (200 mg/L), humic acid (50 mg/L) sodium alginate (50 mg/L) and seawater. As a result, fluxes were recovered to 17% in organic fouling, 15% in inorganic fouling and 14% of seawater fouling after cleaning using DO under the condition of concentrate NaCl 160,000 mg/L of pH 12.

• 대한기계학회논문집
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• 제18권4호
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• pp.903-911
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• 1994

This study addresses the phenomena of bubbling, icing, eruption, component varieties of the evaporated natural gas, and volumetric heat transfer coefficients obtained during the operation of a proposed LNG evaporator between LNG and water in direct contact. In the present investigation, the explosive and eruption phenomena within the water column were not observed during the entire operation of the heat exchanger. Compared with the natural gas produced by conventional LNG evaporator, the analysis of the gas produced by the direct contact LNG evaporator shows that nitrogen, methane, and ethane components were reduced by 0.002~0.007mol%(4~14%), 1.6~1.92mol%(1.9~2.3%) and 0.17~1.28mol%(1.1~8.4%) respectively, while the moisture content was rather increased by 0.51~0.76mol%. The maximum volumetric heat transfer coefficient of the direct contact heat exchanger was found to be $21, 800kW/m^3\cdotK$.

• Journal of Advanced Marine Engineering and Technology
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• 제28권4호
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• pp.618-623
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• 2004

This paper has dealt with the heat storage characteristics of gel type micro size latent heat storage material slurry. The heat release operation to the gel type micro size latent heat storage material slurry was carried out using hot air bubbles by direct contact heat exchange. This experiment was carried out using phase change material of n-paraffin so the heat release amount is higher than cold water system. The parameters of this experiment were concentration of latent heat phase change material, height of heat release bath and inlet velocity of hot air. The main results obtained are as follows : (1) The effect of concentration of latent heat phase change material dispersed with water is very affective to the direct contact heat exchange between hot air and gel type micro size latent heat storage material slurry. (2) It is clarified that the most effective concentration of latent heat phase change material dispersed with water exists around 20mass% at this type of direct heat exchange model experiment.

• 설비공학논문집
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• 제3권3호
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• pp.153-160
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• 1991

Heat transfer characteristics of a direct contact heat exchanger utilizing sieve trays and spray nozzles for steam condensation for the purpose of combining with a LNG evaporator have been investigated with various cooling water flow rates and different vacuum pressures within the heat exchanger for the purpose of steam condensation. Temperature profiles and the volumetric overall heat transfer coefficients in a direct contact heat exchanger have been obtained for comparisons. The results show that the temperature differences between cooling water and steam along the direct contact heat exchanger height are rapidly decreasing and the volumetric overall heat transfer coefficients of the exchanger improves greatly as the inside vacuum pressure increases. The values of the overall heat transfer coefficients at P=-680mmHg have been increased significantly compared with at atmospheric pressure. At given pressure conditions, it is found that the values of average volumetric overall heat transfer coefficients for the sieve tray are found to be approximately 10% higher than those of the spray nozzle.

• 상하수도학회지
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• 제10권3호
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• pp.92-99
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• 1996

The effects of membrane fouling on the water permeability were examined using the hollow fiber microfiltration (HMF)membrane. A membrane module with a pore size of 0.1 micron was submerged in the permeation tank and water bath. The applied pressure was 12.4 kPa for direct solid-liquid separation of activated sludge. As the concentration of MLSS(880~2180mg/l) of the feed solution increased, the decreasing rates of the water flux increased and the membrane was clogged more rapidly. The water flux through the membrane did not increase effectively even with the increase in the applied pressure(40.0~93.3kPa). When the membrane was cleaned with water, the recovery rate of water flux were larger for lower applied pressure. The results indicated that the process of direct solid-liquid separation using HMF membrane was effective at lower pressure.