• 한국농공학회지
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• 제15권1호
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• pp.2904-2912
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• 1973

The density of soil is one of the most important of its engineering properties, and many soil-engineering operations directed toward improving the density characteristics of matecal. This report is a study on relationship between density, permiabilty and other physical properties of compacted soil in various desity grades. The results of the study can be summariged as follow: 1. The optimum moisture content of soil increses with increasing of fine particles and a relationship between both parameter is $w_0=0.1765.n$ Where, n is passing percentage from #200 sieve. 2. The porosity of soil increases with increasing of optimum water content as $e=aw_0+b$ without having relation to compaction ratio. 3. The increment of permeability of soil is high when the compaction ratio is increased and the phenomenon is conspicuous in case of course soil and non-plastic soil. 4. The permeability of soil decreases with increasing of optrimum water content and the phenomenon is conspicuous when compaction ratio decreases. And the permeability is almost constant when optimum water content is more than 25 percent, even though compaction ratio changes. 5. The permeablity of soil increanses when the amount of fine particles is very few, the permeability is almost constant as being impervious condition without having relation to compaction ratio when there in more than 90 percent of fine particles(less than #200 sieve).

• 한국지하수토양환경학회지:지하수토양환경
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• 제23권1호
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• pp.25-29
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• 2018

The effect of soil grinding on total As and Pb concentrations determined by aqua regia method was examined. Among six field-collected, air-dried soil samples tested, soils A, B, C, and E were directly sieved through a $150-{\mu}m$ sieve without grinding and showed 2.18 to 3.03 times higher total As concentrations and 2.62 to 3.45 times higher total Pb concentrations than those of the soil samples prepared to allow all soil particles to pass through the $150-{\mu}m$ sieve by grinding. The reason can be ascribed to the fact that those soils contain fine particles (i.e., < $150{\mu}m$ in diameter) only 4.6 to 6.8% of the total soil weights. On the other hand, for D and F soils, fine particles smaller than $150{\mu}m$ accounted for 57 and 46%, respectively, so that the effect of grinding on As and Pb concentrations were relatively low (As: 1.15 and 1.23 times, Pb: 1.36 and 1.49 times, respectively). The result demonstrates that grinding prior to $150-{\mu}m$ sieving is necessary to ensure the homogeneity of soil samples and hence to obtain more accurate heavy metal concentrations in soils. This is especially true for soil samples with less fine soil particles and/or microaggregates (i.e., below $150{\mu}m$).

• Agricultural and Biosystems Engineering
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• 제1권1호
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• pp.1-6
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• 2000

Using the modified DEM (Distinct Element Model), which we proposed, the effect of cross section of tire lug on the tire performance was simulated. Though the DEM has an advantage over the FEM when it is applied to simulate the behavior of discrete assembly of particles such as soil, there was still a problem in the case of conventional DEM, that the simulated movement of particles was too free. We constructed a new mechanical model (modified DEM) which can take account of the effect of adhesion between particles. It is shown that the soil deformation is simulated by the modified DEM better than the conventional DEM. Comparing the simulated soil reaction to the tire lug with the experimental results, the adequate DEM parameters were found. It is also indicated possible to find the effect of lug cross section shape on the tractive performance of tire by the DEM simulation.

• 한국지반공학회지:지반
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• 제13권2호
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• pp.55-64
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• 1997

계면활성제를 이용하여 홀입자에 흡착된 유기오염물질을 탈착시키는 실험을 실시하였다. 용매로는 중성 세제와 음이온성 세제가 사용되었으며 이를 이용하여 흙으로부터 퀴놀린 및 2-나주들을 분리하였다. 음이온성 세제로 퀴놀린은 약 80%, 2-나푸톨은 90% 가량 탈착되었으며, 중성 세제보다 음이온성 세제가 위의 두 오염물질에 대하여는 덜 효과가 좋은 것으로나타났다. 이온이 제거된 물로 두 오염물질에 대한 탈착실험을 행하여 계면활성제의 탈착능을 물과도 비교하여 보았다.

• 한국농공학회지
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• 제37권3_4호
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• pp.61-71
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• 1995

Natural ground is a composite consisted of the three phases of water, air and soil paircies. Among the three components, water as a material is weU understood but soil particles are not in foundation engineering. Especially, weathered granite soil generally shows a large volumetric expansion when they freeze. And, the stability and durability of the soil have shown decreased with repetitive freezing and thawing processes. These unique charcteristics may cause various construction and management problems if the soil is used as a construction material and foundation layers. This project was initiated to investigate the soil's physical and engineering characteristics resulting from freezing and freezing-thawing processes. Research results may be used as a basic data in solving various problems related to the soil's unique characteristics. The following conclusions were obtained: The degree of decomposition of weathered granite soil in Kangwon-do was very different between the West and East sides of the divide of the Dae-Kwan Ryung. Soil particles distributed wide from very coarse to fine particles. Consistency could be predicted with a function of P200 as LL=0.8 P200+20. Permeability ranged from 10-2 to 10-4cm/sec, moisture content from 15 to 20% and maximum dry density from 1.55 to 1.73 g /cmΥ$^3$ By compaction, soil particles easily crushed, D50 of soil particles decreased and specific surface significantly increased. Shear characteristics varied wide depending on the disturbance of soil. Strain characteristics influenced the soil's dynamic behviour. Elastic failure mode was observed if strain was less than 1O-4/s and plastic failure mode was observed if strain was more than 10-2/s. The elastic wave velocity in the soil rapidly increased if dry density became larger than 1.5 g /cm$^3$ and these values were Vp=250, Vg= 150, respectively. Frost heave ratio was the highest around 0 $^{\circ}C$ and the maximum frost heave pressure was observed when deformation ratio was less than 10% which was the stability state of soil freezing. The state had no relation with frost depth. Over freezing process was observed when drainage or suction freezing process was undergone. Drainage freezing process was observed if freezing velocity was high under confined pressure and suction frost process was occurred if the velocity was low under the same confined process.

• 환경위생공학
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• 제19권4호
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• pp.9-18
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• 2004

In this study, the observation data for the yellow sandy dust phenomena from the year 1999 to 2003 at background sites in Korea were collected at Global Atmospheric Observatory at An-Myeon island and its temporal variation were analyzed. The chemical characteristics of the fine particles were also analyzed in order to evaluate sources of the yellow sandy dust particles. The results showed that the monthly average mass concentration of the fine particles was the highest in springtime and the lowest in summertime in general. The magnitude of its variation was also the highest in March in which the occurrence of yellow sandy dust was the most frequent and thus the number of samples was the largest, while the lowest in June through September. The yearly variation of ion components contributions to the total mass concentration of the fine particles was slowly decreasing, showing that $63\%$ in 1999, $59\%$ in 2000 and $56\%$ in 2003. The most prevalent ion components in the fine particles were found to be $NO_3$ and $SO_4^{2-}$, which are known to be source materials of acidic precipitation, and $NH_4^+$, a neutralizing material of the acid precipitation. Relative proportion of metal components in the fine particles was calculated as $14\%$ in average, and their concentrations are in an order of Fe > Al > Na > Ca > Zn > Pb > Cu > Mn > Ni > Cd > Cr > Co > U. The results indicated that main sources of the metals was soil-originated Fe, Al, Ca, and Mg, and the contribution of anthropogenic air Pollution-originated Zn, Pb, Cu, Mn were also high and keep slightly increasing. Statistical analysis showed that the chemical components could be divided into soil-originated group of Mg, Al, Ca, Fe, and Mn and air pollution-originated group of $NO_3$, Zn, Pb, and they are occupying more than $60\%$of all the components in the dusty sand. The results explain that An-Myeon island is more influenced by soil-originated source than ocean-originated one and also the influencing strength of anthropogenic poilution-originated source is less than $50\%$ of that of soil-originated sources. Compared to non-yellow sandy period, the yellow sandy dust period showed that the amounts of soil-originated $Mg^{2+}$ and $Ca^{2+}$ and ocean-originated $Na^+$ and $Cl^-$ were increased to more than double and the metals of Mg, Al, Ca, Fe were also highly increased, while micro metal components such as Pb, Cd, Zn, which have a tendency of concentrating in air, were either decreased or maintained at nearly constant level. In the period of yellow sandy dust, a strong positive correlation was observed between water soluble ions and between metals in terms of its concentration, respectively. Factor analysis showed that the first group being comprised of about $43\%$ of the total inorganic components was affected by soil and they are ions of $Na^+,\;Mg^{2+}\;and\;Ca^{2+}$ and metals of Na, Fe, Mn and Ni. The result also showed that the metals of Mg and Cr were classified as second group and they were also highly affected by soil sources.

• 한국초전도ㆍ저온공학회논문지
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• 제25권3호
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• pp.13-17
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• 2023

Magnetic separation technology for small paramagnetic particles has been desired for the volume reduction of contaminated soil from the Fukushima nuclear power plant accident and for the separation of scale and crud from nuclear power plants. However, the magnetic separation for paramagnetic particles requires a superconducting high gradient magnetic separation system applied, hence expanding the bore diameter of the magnets is necessary for mass processing and the initial and running costs would be enormous. The use of high magnetic fields makes safe onsite operation difficult, and there is an industrial need to increase the magnetic separation efficiency for paramagnetic particles in as low a magnetic field as possible. Therefore, we have been developing a magnetic separation system combined with a selection tube, which can separate small paramagnetic particles in a low magnetic field. In the previous technique we developed, a certain range of particle size was classified, and the classified particles were captured by magnetic separation. In this new approach, the fluid control method has been improved in order to the selectively classify particles of various diameters by using a multi-stage selection tube. The soil classification using a multi-stage selection tube was studied by calculation and experiment, and good results were obtained. In this paper, we report the effectiveness of the multi-stage selection tube was examined.

• 한국지하수토양환경학회지:지하수토양환경
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• 제9권4호
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• pp.52-61
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• 2004

음이온 비소와 양이온 아연 및 니켈로 오염된 토양을 산세척으로 복원하기 위해서 토양세척 파일럿 장비를 이용해서 토양의 물성과 산세척 특성 및 미세토양과 용존 오염물의 발생 특성을 고찰하였다. 비소와 아연 및 니켈의 pH $2{\sim}3$에서 산세척시 황산과 인산은 공존 경쟁 음이온의 존재로 비소의 제거 효율을 높였고, 염산은 비소, 니켈, 아연을 동시에 효율적으로 제거하였다. 세척조에서 화학적 용출은 임계체류시간 이상에서 세척 효율이 일정해졌고, 산에 의한 용출 가능한 존재형태는 교환성 및 산화물 결합과 유기성 결합형태, 그리고 부분적으로 잔류형태였다. 오염 토양의 입도에 따른 과립의 토양입자의 토양세척 효율은 높지만, 미세입자($<74{\mu}m$)는 오염물질의 농집 현상이 일어나서 제거효율이 감소했다. 또한, $<149{\mu}m$ 이하의 미세토양을 물리적 입도 분리시 전체 세척효율이 향상되었다. 따라서, 미세토양의 양이 최소가 되고 화학적 용출이 최대가 되는 세척 효율 교차지점에서 화학적 용출과 미세토양의 분리가 토양세척의 증가된 효율을 보여 주었다.

• 농업과학연구
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• 제48권4호
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• pp.843-853
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• 2021

The objectives of this paper were to simply estimate soil loss levels as caused by wind in reclaimed tidal flat land (RTFL) and the threshold wind velocity in the RTFL. For this experiment, RTFL located at Haenam Bay was selected and a total of 150 soil samples were collected at the Ap horizon from the five soil series. The particle distribution curves, including the limit of the non-erodible particle size (D > 0.84 mm) for each Ap horizon soil, show that the proportions of non-erodible particle sizes that exceeded 0.84 mm were 4.3% (Taehan, TH), 8.9% (Geangpo, GP), 0.5% (Bokchun, BC), 1.6% (Poseung, PS) and 1.4% (Junbook, JB), indicating that the amount of non-erodible soil particles increased with an increase in the sand content. The average monthly, daily and instantaneous wind velocities were higher than the threshold friction velocity (TFV) calculated according to the dynamic velocity (V_d) by Bagnold, while the average monthly wind velocity was lower than those of the TFV suggested by the revised wind erosion equation (RWEQ) and wind erosion prediction system (WEPS). The susceptible proportions of erodible soil particles from the Ap horizon soil samples from each soil series could be significantly influenced by the proportion of sand particles between 0.025 and 0.5 mm (or 0.84 mm) in diameter regardless of the threshold wind velocity. Thus, further investigations are needed to estimate more precisely soil erosion in RTFL, which shows various soil characteristics, as these estimations of soil loss in the five soil series were obtained only when considering wind velocities and soil textures.

• 한국초전도ㆍ저온공학회논문지
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• 제23권3호
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• pp.26-31
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• 2021

Advanced classification of Cs contaminated soil by using a magnetic force-assisted selection pipe was investigated. A selection pipe is a device that sort particles depending on their particle size, based on the relationship between buoyancy, drag, and gravity force acting on the particles. Radioactive cesium is concentrated in small-particle size soil components with a large specific surface area. Hence, the volume of the Cs contaminated soil can be reduced by recycling the large-particle size soil components with low radioactive concentration. One of the problems of the selection pipe was that the radioactive concentration of the stayed soil in the selection pipe exceeds 8000 Bq/kg, which is the standard value of recycling of Cs contaminated soil, due to low classification accuracy. In this study, magnetic fields were applied to the lab-scale selection pipe from upper side to improve the classification accuracy and to reduce the radioactive concentration of the stayed soil.