• Journal of Korean Society of Environmental Engineers
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• v.35 no.8
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• pp.607-612
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• 2013

Soil ecological risk assessment requires terrestrial toxicity data based on trophic levels including plants, earthworms, nematodes, and springtails. To expand the trophic levels, it is needed to consider primary producer algae, nearly distributed in terrestrial environment, as representative terrestrial test species. In this study, we collected research cases focused on soil-related test species and exposure media from SCI papers, and analyzed exposure media, test species, test chemicals, and other test methods, for reviewing research trends of soil-related algal toxicity. Up to now, in the soil-related algal toxicity, test species were 8 cases (Pseudokirchneriella subcapitata, Chlorella vulgaris, Scenedesmus bijugatus, Chlorococcum infusionum, Scenedesmus subspicatus, Nostoc linckia, Synechococcus elongatus, and Chlorococcum sp.) and endpoints were cell count or photosynthetic pigment content. Also, 5 of exposure media were liquid medium, soil extracts, porewater, agar medium, and soil. Most of papers used algae isolated from natural soils or soil extracts. There were only one case for assessing algal toxicity in soil medium. More researches regarding algal toxicity in soil environments need to be conducted consistently.

• Clean Technology
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• v.16 no.2
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• pp.145-152
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• 2010

Various technical methods are applied for removing water from the water-retaining media, and the energy efficiency is the main concern in those methods. The electroosmotic process is studied as an efficient way for dewatering. An experimental electroosmotic reactor is designed and used for evaluating the effects of operational variables. The operational variables such as the electrical fields and the structure of water-retaining medias were studied. Three different shapes of polarized electric fields in ranges of 0-100 V/cm and 0-10 kHz are used as the source of electric voltage. The effect of electroosmotic process with respect to the structural variation is estimated by filling the electroosmotic reactor with the glass beads in 0.18 mm, 0.35 mm and 1.2 mm in diameters. 6% of water removal is obtained in the simulating electroosmotic reactor of glass beads. The estimated energy consumption in the simulating electroosmotic was 330~490 cal/g-water.

• Journal of Soil and Groundwater Environment
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• v.14 no.6
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• pp.101-107
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• 2009

Carboxymethyl cellulose (CMC) as stabilizer is expected to facilitate in-situ delivery of zero-valent iron (ZVI) nanoparticles in a contaminated aquifer because it increases dispersity of ZVI nanoparticles. This work investigated the transport of CMC-stabilized ZVI nanoparticles (CMC-Fe) using column breakthrough experiments. The ZVI nanoparticles (100 mg/L Fe) were transportable through sand porous media. In contrast, non-stabilized ZVI nanoparticles rapidly agglomerate in solution and are stopped in sand porous media. At pH 7 of solution approximately 80% CMC-Fe were eluted. When the pH of solution is below 5, 100% CMC-Fe were eluted. These results suggest that the mobility of CMCFe was increased as pH decreases. In the mobility test under different ionic strengths using $Na^+$ and $Ca^{2+}$ ions, there was no signigficant difference in the mobility of CMC-Fe. Also, in the experiments of effect of clay and natural organic mater (NOM) on the mobility of ZVI, there was no significant difference in the mobility of CMC-Fe not only between 1 and 5% clay, but 100 and 1000 mg/L NOM. The results from this work suggests that the CMC-Fe nanoparticles could be easily delivered into the subsurface over a broad range of ionic strength, clay and NOM.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.7 no.3
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• pp.458-464
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• 2006

Bioremediation has been recognized as one of the best tools for hydrocarbon contaminated soil and nearby groundwater which had been heavily polluted in industrial areas. Degradation of PAHs in PAH-polluted loam soil were investigated under polyurethane foam environment with adsorbed bacteria Pseudomonas sp. (KCCM 40055) in order to acquire vital data for the environmentally-friendly process and material. macroporous commercial polyurethane foam that is widely used for microbial attachment in such as sewage treatment was selected for experiments. We also examined the microbial adherence upon the media. SR9-35C/G among the PU samples showed the highest degree of attachment and bioconversion. The conversion efficiency increased with moisture content of soil.

• Journal of the Mineralogical Society of Korea
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• v.22 no.4
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• pp.313-324
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• 2009

We explore the effect of particle shape and size on 3-dimensional (3D) network and pore structure of porous earth materials composed of glass beads and silica gel using NMR micro-imaging in order to gain better insights into relationship between structure and the corresponding hydrologic and seismological properties. The 3D micro-imaging data for the model porous networks show that the specific surface area, porosity, and permeability range from 2.5 to $9.6\;mm^2/mm^3$, from 0.21 to 0.38, and from 11.6 to 892.3 D (Darcy), respectively, which are typical values for unconsolidated sands. The relationships among specific surface area, porosity, and permeability of the porous media are relatively well explained with the Kozeny equation. Cube counting fractal dimension analysis shows that fractal dimension increases from ~2.5－2.6 to 3.0 with increasing specific surface area from 2.5 to $9.6\;mm^2/mm^3$, with the data also suggesting the effect of porosity. Specific surface area, porosity, permeability, and cube counting fractal dimension for the natural mongolian sandstone are $0.33\;mm^2/mm^3$, 0.017, 30.9 mD, and 1.59, respectively. The current results highlight that NMR micro-imaging, together with detailed statistical analyses can be useful to characterize 3D pore structures of various porous earth materials and be potentially effective in accounting for transport properties and seismic wave velocity and attenuation of diverse porous media in earth crust and interiors.

• Water for future
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• v.25 no.3
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• pp.65-77
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• 1992

The purpose of this study is to analyse existing hysteresis models and to propose a new type of model. The existing hysteresis models are classified by three types: interpolation model, scaling model and domain model, of which the domain model is based on the theoretical approach. Models which need one branch of hysteresis loop for calibration are developed based on the independent domain concept, however, they are not successful to accurately simulate the real data and Rubicon Sandy Loam and Dune Sand. There is a possibility that a new model is based on the dependent domain model considering the pore blockage effect against air entry for homogeneous porous media(modelIII-1, Mualem, 1984). Concludingly, a new type of hysteresis model is proposed by simplifying ModelIII-1 using a proper assumption.

• Journal of the Korea Organic Resources Recycling Association
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• v.17 no.4
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• pp.103-111
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• 2009

Moisture is one of the important design factors that affects to the changes of physical properties and air permeability in the composting matrix. This study examines the effects of moisture during the wetting and drying procedure on physical properties like bulk density, particle size, free air space and air permeability in the sawdust used as the bulking agent in composting process. During both procedures of wetting and drying of the water, with increasing moisture content, bulk density and particle size increased, but FAS decreased. In the range of near 40 to 60% moisture content on a wet basis, particle size and FAS in wetting procedure were larger and higher than those in drying procedure. During wetting procedure, pressure drop continuously decreased ranging from near 20 to 60% moisture content, despite of decreasing FAS as a consequence of increasing moisture, and then over the range of 60% moisture content, pressure drop rapidly increased to the saturated moisture condition while the pore space was filled with the water. On the other hand, during drying procedure, pressure drop decreased from the saturated condition to 40% moisture content. In the recommended range of 50 to 60% moisture content for composting operation, pressure drop in wetting procedure were lower than in drying procedure. For the enhancement of the air permeability in the composting matrix, the wetting procedure was proper than the drying procedure, and the optimum moisture content for the efficient composting operation was appeared to be near 60%.

• Economic and Environmental Geology
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• v.46 no.1
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• pp.51-61
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• 2013

Researches on the oil recovery enhancement using the nanotechnology has recently been studied in the United States. The previous researches has focused mainly on the flow characteristics of nanoparticles in porous media, and the stability of the nano-emulsion itself. However, the analysis did not deal with the size effects between a nano-emulsion and the pore size which has an important role when nano-emulsion flows in the porous media. In this research, nano-based emulsion was fabricated which is able to be applied for the enhanced oil recovery techniques and its characteristics was analyzed. In addition, in order to identify the characteristics of nano-emulsions flowing through the porous media, the size effect was analysed by filtering test. According to the results, when the emulsion was fabricated, SCA(Silane Coupling Agent) or PVA(Poly Vinyl Alcohol) are added to improve the stability of emulsion. As the ratio of the decane to water increased, the viscosity of emulsion and the droplet size also increased. For the filtering test at the atmospheric conditions, the droplet did not go through the filter; only the separated water from the emulsion was able to be filtered. This phenomenon occurred because the droplet was not able to overcome the capillary pressure. At the filtering test by suction pressure, most of the emulsion was filtered over the filter size of $60{\mu}m$. However, the ratio of filtration was rapidly degraded at less than $45{\mu}m$ filters. This is caused due to deformation and destruction of the droplet by strong shear stress when passing through the pore. The results from the study on the basic characteristic of nano-emulsion and filtering test will be expected to play as the important role for the fabrication of the stable nano-emulsion or the research on the recovery of residual oil in porous media.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.24 no.5
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• pp.415-421
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• 2012

Stirling engine is an external combustion engine, whose efficiency approaches that of Carnot engine with the help of a regenerator. The regenerator is a heat exchanger composed of porous medium, whose performance is dependent on the pore structure. Three types of pore structures are considered in the present study. They are wire screen, random wire and composite structure, i.e. a combination of wire screens with different hydraulic diameters. The porosity more highly affects the performance of a regenerator compared to the hydraulic diameter. The random wire can yield high effectiveness even at a high porosity. The composite mesh gives better performance when the hydraulic diameter decreases in the direction from hot side to cold side.

• 한국신재생에너지학회:학술대회논문집
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• 2008.05a
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• pp.595-596
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• 2008

가스 하이드레이트의 생성속도와 전환율을 높이며, 동시에 생성유도시간을 억제하기 위한 방법으로 다공질 물질을 활용하여 공극 내에 물을 함침시킨 후 가스와 반응시키는 제조방법을 개발하였다. 내용적 10 L 의 대용량 고압 반응기를 제작하여 실험을 수행하였으며, 장치 대형화에 따른 다공질 실리카겔의 다짐현상에 의한 발열제어 등에 대한 문제점은 특별히 나타나지는 않았다. 하이드레이트 형성을 위한 구동력이 높을수록 생성속도가 좋아지는 것을 확인하였다. 일반 벌크상 하이드레이트 제조법과 비교하여 매우 높은 생성속도 및 전환율, 거의 제거된 생성유도시간 등은 응용기술로 활용하기에 매우 바람직한 특성으로써 선택적인 가스분리, 가스저장 매체로 활용이 가능하다.