• 한국의류학회지
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• 제34권7호
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• pp.1175-1183
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• 2010

This study investigates the effect of polarity of oily soil on adhesion of oily and particulate soil to PET fabric in oily/particulate mixed soil systems. The potential energy of interaction between two particles was examined as a fundamental environment of adhesion of soil to fabrics. The ${\zeta}$-potential of ${\alpha}-Fe_2O_3$ particles was measured by a microelectrophoresis method, and the potential energy of interaction between two particles was calculated by using the Verwey-Overbeek theory. The ${\zeta}$-potential of particle and the potential energy of interaction between two particles was slightly influenced by the polarity and type of oily soil, but increased with the increased anionic surfactant concentration and amount of oily soil. The adhesion of oily soil to fabric increased with the additional amount of polarity of oily soil and decreased surfactant concentration that was relatively high at a temperature of $60^{\circ}C$ surfactants solution. The adhesion of ${\alpha}-Fe_2O_3$ particle to PET fabric decreased with an increased amount and polarity of oily soil and increased surfactant concentration Although some similarity exists, the general trend of the adhesion to fabric by particulate soil differ from oily soil.

• 한국조경학회지
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• 제25권2호
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• pp.94-103
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• 1997

The purpose of this study is to find out the effects of brick paved under-surface soil physical properties which are changed by fixed trampling. Thus, a sandy loam which is known as a profitable soil for plants is used an experimental soil to study the changes of the soil physical properties. It is related to sand bed's thickness & particle size which are settled by experimental variable factors. According to the variation of sand bed's particle size, bulk density and soil hardness at natural dryed soilcondition result in 0.075~2.00mm>2.00~5.00mm>2.00~8.00mm>5.00~8.00mm, and water content at natural dryed soil condition are observed being insensible change rate from the point that sand thickness is 30~40mm and more sand bed's thickness constructed by the variation of sand bed's thickness.

• 한국의류학회지
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• 제34권4호
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• pp.653-662
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• 2010

This study investigates the effect of particle size on the detergency of particulate soil using an $\alpha-Fe_2O_3$ particle as the model. Monodispersed spherical $\alpha-Fe_2O_3$ particles were prepared by the hydrothermal aging of an acidic $FeCl_3$ and HCl solution. The $\xi$-potential of PET fiber was measured by the streaming potential method. The potential energy of interaction between the particle and fiber was calculated using the heterocoagulation theory for a sphere-plate model. The $\xi$-potential of PET fiber and potential energy of interaction between particles and fiber increased with a decreasing particle size in a DBS solution. However, in the nonionic surfactant solution, the $\xi$-potential signs of PET fiber and $\alpha-Fe_2O_3$ particles were (-) and (+), respectively; there was no repulsive power between the particles and substrate. The adhesion of particles to the fabric increased with increasing particle size in the anionic surfactant solution and their removal from the fabric increased with a decreasing particle size. The adhesion of particles to the fabric and their removal from the fabric was biphasic with a maximum and minimum at 0.1% concentration of the surfactant solution. In the nonionic surfactant solution the adhesion of particles to fabric and their removal from the fabric were greater than the ones in the anionic surfactant DBS solution.

• Geomechanics and Engineering
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• 제9권6호
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• pp.815-827
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• 2015

The mechanical behavior of soil and soil-rock mixture is investigated via the discrete element method. A non-overlapping combination method of spheres is used to model convex polyhedron rock blocks of soil-rock mixture in the DEM simulations. The meso-mechanical parameters of soil and soil-rock interface in DEM simulations are obtained from the in-situ tests. Based on the Voronoi cell, a method representing volumtric strain of the sample at the particle scale is proposed. The numerical results indicate that the particle rotation, occlusion, dilatation and self-organizing force chains are a remarkable phenomena of the localization band for the soil and soil-rock mixture samples. The localization band in a soil-rock mixture is wider than that in the soil sample. The current research shows that the 3D discrete element method can effectively simulate the mechanical behavior of soil and soil-rock mixture.

• 한국농공학회논문집
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• 제65권3호
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• pp.15-28
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• 2023

The compaction properties of the soil change depending on the physical properties, and are also affected by crushing of the particles. Since the particle size distribution of soil affects the engineering properties of the soil, it is necessary to analyze the material properties to understand the compaction characteristics. In this study, the size of each sieve was classified into four in the particle size analysis as a material property, and the compaction characteristics were evaluated by multiple regression and maximum dry unit weight. As a result of maximum dry unit weight prediction, multiple regression analysis showed R² of 0.70 or more, and DNN analysis showed R² of 0.80 or more. The reliability of the prediction result analyzed by DNN was evaluated higher than that of multiple regression, and the analysis result of DNN-T showed improved prediction results by 1.87% than DNN. The prediction of maximum dry unit weight using particle size distribution seems to be applied to evaluate the compacting state by identifying the material characteristics of roads and embankments. In addition, the particle size distribution can be used as a parameter for predicting maximum dry unit weight, and it is expected to be of great help in terms of time and cost of applying it to the compaction state evaluation.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2010년도 춘계 학술발표회
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• pp.314-323
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• 2010

Recently, granular soils having a large particle size are frequently used as a filling material in the construction of foundation, harbor, dam, and so on. The shear behavior of this granular soil plays a key role in the stability of structures. For example, soil particle crushing occurring at the interface between structure and soil and/or within soil mass can cause the disturbance of ground characteristics and consequently induce an issues in respect of stability of structures. In order to investigate the shear behavior according to an existence and nonexistence of particle crushing, numerical analyses were conducted by using the DEM(Discrete Element Method)-based software program PFC(Particle Flow Code). Using the crushing model and non-crushing model which were created in this study, numerical analyses of ring shear test were conducted and their results were analyzed and compared. In general, landslide and slope stability are accompanied by a large displacement and consequently not only a peak strength but also a residual strength are very important in the analysis of landslide and slope stability. However the direct shear test which has been commonly used in the determination of shear strength parameters has a limitation on displacement therefore the residual strength parameters can not be obtained. The characteristics of residual shear behavior were investigated through the numerical analyses in this study.

• 한국지반공학회논문집
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• 제30권11호
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• pp.25-37
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• 2014

현장 지반에는 점토 또는 모래만 존재하기 보다는 다양한 크기의 흙이 서로 섞여 존재하는 경우가 많다. 본 연구에서는 이와 같이 모래가 포함된 점토에서 함수비 증가에 따른 흙의 유동 특성을 예측하기 위해 흙기둥 붕괴실험과 이를 위해 개발한 입자법으로 대변형 시뮬레이션을 실시하였다. 먼저 카올리나이트에 모래 함유량을 0, 10, 25, 그리고 50%까지 증가시키면서 직경 7cm, 높이 13cm의 흙기둥 붕괴실험을 실시하였으며, 시간에 따른 흙기둥의 형상 변화를 관찰하였다. 모래 함유량이 다른 각각의 흙기둥에 함수비를 40, 60, 그리고 80%로 증가시키면서 총 12 종류의 흙기둥 붕괴실험을 실시하였으며, 본 연구에서 개발한 입자법으로 시간에 따른 흙기둥의 변화를 시뮬레이션하였다. 점토의 함수비와 모래 함유량에 따른 비배수전단강도와 소성지수의 변화를 고려한 최대소성전단계수를 입자법의 점성항에 적용하여 토사 대변형을 시뮬레이션하였다. 실험 결과 모래 함유량이 동일한 경우 함수비가 증가할수록 변형이 크게 발생하였으며, 동일한 함수비라도 모래 함유량이 증가함에 따라 흙기둥의 변형은 크게 발생하였다. 최대 변형은 함수비 80%, 모래 함유량 50%인 흙기둥의 직경이 7cm에서 22cm로 3배 이상 발생하였으며, 이와 같은 흙기둥 실험에서 관찰된 토사의 대변형 거동 및 응력 변화를 개발한 입자법이 비교적 잘 예측할 수 있었다.

• Geomechanics and Engineering
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• 제36권3호
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• pp.295-301
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• 2024

Understanding the post-liquefaction shear behavior is crucial for predicting and assessing the damage, such as lateral flow, caused by liquefaction. Most studies have focused on the behavior until liquefaction occurs. In this study, we performed undrained multi-stage tests on clean sand, sand-silt mixtures, and silty soils to investigate post-liquefaction shear strain based on soil compressibility. The results confirmed that it is necessary to consider the soil compressibility and the shape of soil particles to understand the post-liquefaction shear strain characteristics. Based on this, an index reflecting soil compressibility and particle shape was derived, and the results showed a high correlation with post-liquefaction small resistance characteristic regardless of soil type and fine particle content.

• 한국지하수토양환경학회지:지하수토양환경
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• 제28권6호
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• pp.9-15
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• 2023

In order to properly evaluate the spatio-temporal variations of groundwater flow, the data obtained in field experiments should be corroborated into numerical simulations. Particle tracking method is a simple simulation tool often employed in groundwater simulation to predict groundwater flow paths or solute transport paths. Particle tracking simulations visually show overall the particle flow path along the entire aquifer, but no previous simulation studies has yet described the parameter values at grid nodes around the particle path. Therefore, in this study, a new technical approach was proposed that enables acquisition of parameters associated with particle transport in grid nodes distributed in the center of the particle path in groundwater. Since the particle tracking path is commonly referred to as streamline, the algorithm and codes developed in this works designated streamline analysis method. The streamline analysis method can be applied in two-dimensional and three-dimensional finite element or finite difference grid networks, and can be utilized not only in the groundwater field but also in all fields that perform numerical modeling.

• Journal of Microbiology and Biotechnology
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• 제23권9호
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• pp.1279-1286
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• 2013

Particle size and metal species are important to both soil microbial toxicity and phytotoxicity in the soil ecosystem. The effects of CuO and ZnO nanoparticles (NPs) and microparticles (MPs) on soil microbial toxicity, phytotoxicity, and bioaccumulation in two crops (Cucumis sativus and Zea mays) were estimated in a soil microcosm. In the microcosm system, soil was artificially contaminated with 1,000 mg/kg CuO and ZnO NPs and MPs. After 15 days, we compared the microbial toxicity and phytotoxicity by particle size. In addition, C. sativus and Z. mays were cultivated in soils treated with CuO NPs and ZnO NPs, after which the treatment effects on bioaccumulation were evaluated. NPs were more toxic than MPs to microbes and plants in the soil ecosystem. We found that the soil enzyme activity and plant biomass were inhibited to the greatest extent by CuO NPs. However, in a Biolog test, substrate utilization patterns were more dependent upon metal type than particle size. Another finding indicated that the metal NP uptake amounts of plants depend on the plant species. In the comparison between C. sativus and Z. mays, the accumulation of Cu and Zn by C. sativus was noticeably higher. These findings show that metal oxide NPs may negatively impact soil bacteria and plants. In addition, the accumulation patterns of NPs depend on the plant species.