• Proceedings of the Membrane Society of Korea Conference
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• 1993.10a
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• pp.52-53
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• 1993

투과증발 분리를 위하여 여러가지 막 소재와 공정을 개발하기 위한 노력이 다방면에서 이루어지고 있으며, 이에 관한 자료도 많이 제시되고 있으나 고분자 분리막의 개발은 아직도 미흡한 상태이다. 한편 투과증발 분리는 공정자체는 매우 간단하면서도 분리막의 투과성능에 따라 분리효율이 달라지기 때문에 여러종류의 막의 개발이 필요하다. 따라서 본 연구에서는 물/유기용제 혼합액에서 물을 분리하기 위하여 친수성이 강한 두 고분자 재료인 poly(vinyl alcohol)(PVA)와 carboxymehtylcellulose(CMC)를 브랜드하여 목적하는 분리기능을 갖는 새로운 막을 제조하여, 물/유기용제, 혼합액의 분리특성을 브랜드비와 온도 및 농도 그리고 분리시간에 따라 각각 검토하였다.

• Journal of Korean Society of Environmental Engineers
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• v.32 no.5
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• pp.461-468
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• 2010

This study investigated variation of rainwater quality by seasonal and storage duration of rainwater in Changwon city. Seasonally, the pollutants concentration of rainwater were higher in spring and winter. In the case of rainwater and storage rainwater quality, pH of rainwater was 4.3, storage rainwaters were 6.0 and Turbidity increased about 8 times from 1.82 NTU to 14.61 NTU. The changes of storage water quality during the storage period, initial KMnO4 consumption rainwater was exceeded drinking water standard. Total solid in rainwater was detected as 116 mg/L, it tended to stable at around 70∼80mg/L after storage period for a 6day.

• Membrane Journal
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• v.10 no.3
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• pp.130-138
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• 2000

Polyethersulfone (PES) asymmetric membranes for gas separation were prepared by dry/wet phase inversion method and their separation properties for CO$_2$ and N$_2$ gases were investigated. The effects of important variables such as composition of casting solution and evaporation time in preparation of asymmetric gas membrane on membrane morphology and the separation properties were analyzed and the optimum condition of membrane preparation was established. To compensate the defects like pinholes existed on skin layer of the membrane prepared, the membranes were coated with silicone resin. By comparing separation properties after coating with those before coating, we found that the coating of silicone resin was effective to enhance the separation properties. The casting solution mainly used in this study consisted of PES, N-methyl-2-pyrrolidone, acetone, ethanol and distilled water was used as coagulation agent. It was shown that the selectivity for CO$_2$/N$_2$ was getting higher but the permeability decreases, as the contents of PES and volatile organic solvent and evaporation time increased. The selectivity for CO$_2$/N$_2$ and permeability of CO$_2$ of the membrane prepared under the optimum condition were found to be 61 and 21 GPU, respectively.

• Journal of the Korean Geotechnical Society
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• v.32 no.5
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• pp.37-48
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• 2016

This study aims to figure out the behavior of runoff and drainage of pervious sidewalk block in actual construction environment by experiments. The specimens with surface layer and bedding layer are subjected to the drainage test by considering unsaturated condition and unique rainfall condition in urban areas. The repeated drainage test and clogging test were conducted with time intervals, and 3D X-ray CT image analysis and evaporation test were carried out for a quantitative analysis of drainage test. The results present that the spatial distribution of pores by evaporation for time intervals induces runoff. Especially, the bedding layer under the block is significantly critical in overall hydraulic behavior such as drainage and evaporation compared to the surface layer. Moreover, the sediments in pores promote the change in pores by evaporation and this induces deteriorated drainage capacity which is hard to recover. In addition, it is revealed that the maximum runoff height grows as the drainage capacity declines depending on the pre-wetting condition.

• Membrane Journal
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• v.3 no.3
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• pp.117-125
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• 1993

The CA reverse osmosis membranes were prepared and were studied the effects of parameters in membrane performance. The dope solutions were composed of polymer, formamide, acetone and 2-methoxyethanol. And it was prepared flat type membranes. The membranes were measured flux and rejection. The experimental factors such as polymer concentration, additive type, solvent evporation period, annealing temperture, and applied pressure were changed to investigate the effects of these on the membranes. And the transport parameters were also calculated at reverse osmosis medel for prepared membranes.

• Journal of Korea Water Resources Association
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• v.52 no.5
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• pp.325-335
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• 2019

To characterize historical droughts in the conterminous United States (CONUS), we estimated the actual evapotranspiration ($ET_a$) in the CONUS using the generalized complementary relationship (GCR) for 1895-2016. The $ET_a$ estimates were compared against simulations from the Noah land surface model (LSM). In this study, the evapotranspiration (ET) deficit defined as the difference between the wet-environment ET ($ET_w$) and $ET_a$ was then normalized to calculate the Standardized Evapotranspiration Deficit Index (SEDI) across the CONUS for the years 1895-2016. The SEDI was compared to the Standard Precipitation Index (SPI) at various time scales. The results showed that the GCR $ET_a$ was slightly higher than the Noah LSM-simualted $ET_a$. As time scales increased, the correlation between the SEDI and the SPI was higher. This study suggests that the GCR has promise as a tool in the estimation of $ET_a$ and SEDI can be useful for the drought characterization.

• Journal of Energy Engineering
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• v.23 no.3
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• pp.174-180
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• 2014

Experimental study of liquid nitrogen pool spread is carried out when it is continuously released. The liquid nitrogen spreads over a cement mortar plate with continuous release. Evaporation rate per unit area of the liquid nitrogen is measured using a digital balance, and a spreading distance of the liquid pool is measured by thermocouples. It is discovered that the evaporation rate per unit area of liquid nitrogen tends to decrease as the liquid pool spreads.

• Journal of Korean Society for Geospatial Information Science
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• v.14 no.2 s.36
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• pp.55-62
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• 2006

Droughts have been an important factor in disaster management in Korea because she has been grouped into nations of lack of water. Satellite imagery can be applied to droughts monitoring because it can provide periodic data for large area for long time. This study aims to present a process to analyze droughts in large area using satellite imagery. We estimated evapotranspiration in large area using NDVI data acquired from satellite imagery. For satellite imagery, we dealt with MODIS data operated by NASA. The evapotranspiration estimated from satellite imagery was combined with precipitation data and potential evapotranspiration data to estimate water balances. Using water balances we could analyze droughts effectively in our object area. As the result of this study, we could increase the usability of satellite imagery, especially in droughts analysis.

• Membrane Journal
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• v.9 no.4
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• pp.215-220
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• 1999

The asymmetric polyimide [PI] membrane with good solvent-resisting and heat-resisting properties was prepared by using the phase inversion method from polyamic acid, and its pervaporation separation characteristics of water-acetic acid system were studied. It was appeared from the prepared membranes that the best non-solvent of polyamie acid for the phase inversion was toluene. The best heat-treatment condition for the imidization of polyamic acid was 1 hr heating at each of the temperatures, 373, 473, and 573 K The thermal durability and chemical stability during the pervaporation separation of water-acetic acid of the prepared PI membrane was superior. The pervaporation characteristics of prepared membrane were 180 of separation factor and 0.5 kg/$m^2$hr of total flux for 80 wt% acetic acid feed.

• Proceedings of the Korea Water Resources Association Conference
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• 2017.05a
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• pp.217-217
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• 2017

물 순환이란 물이 지표면으로부터 증발하거나 바다로부터 증발하여 습한 공기가 기단을 형성한 후 적합한 조건이 형성되면 강수를 초래하는 과정이라고 볼 수 있다. 여기서 강수는 여러 경로 즉, 증발산, 지표흐름, 침투, 침루 등을 통해 다시 순환과정을 거친다. 최근 도시화로 인한 불투수면적의 증가로 기후변화, 홍수지체시간 감소, 첨두 및 유출총량의 증가, 침투능 및 증발산량의 감소 등 자연하천의 유출특성과는 다른 유출특성이 나타나며, 물 순환 체계가 왜곡되어 지하수위는 낮아지고, 하천의 유량은 감소되는 등 하천의 정상적인 기능이 저하되고 있다. 이에 우리나라에서는 환경부 및 국토교통부 등 정부기관과 지방자치단체에서 법과 조례를 제정하여 저영향개발기법 (LID, Low Impact Development)을 적용하도록 권고하고 있으며 신도시 개발사업 시 왜곡된 도시의 물 순환체계를 개선하기 위하여 저영향개발기법을 적용하고 있다. 저영향개발 기법의 정량적인 효과를 검증하기 위해서는 미환경청 (U.S. EPA., United States Environmental Protection Agency)에서 개발한 SWMM모델을 이용하여야 한다. 본 연구에서는 도시화로 인해 왜곡된 물순환체계 개선을 위하여 다양하게 설계된 저영향개발기법의 정량적인 효율을 SWMM 모델을 통해 산정하고, 장기적인 측면에서 물순환 회복에 적합한 저영향개발기법의 배치 최적화를 제안하고자 한다.