• 한국토양환경학회지
• /
• 제1권1호
• /
• pp.67-79
• /
• 1996

점토는 물과 같이 극성이 큰 유체가 존재할 때 매우 낯은 투수계수를 갖게된다. 따라서 극성이 매우 낮은 탄화수소계연료나 할로겐화 유기용제등은 간극수(pore water)를 밀어내지 못하기 때문에 점토공극내로 이동할 수 없다. 최근들어 대기오염 저감대책의 하나로 알콜이나 MTBE(methyl-tert-butyl ether)등과 같은 가솔린 산소첨가제의 사용량이 늘어나고 있는 추세에 있다. 이들 산소첨가제는 극성을 띠고 있으며 물에 대한 용해도가 매우 높기 때문에 간극수를 교체하여 가솔린이나 유기용제등의 점토층내 이동을 촉진시킬 가능성을 갖고 있다. 본 연구에서는 가솔린-알콜 혼합연료(gasohol)의 압밀점토층 내에서의 이동을 실험적으로 살펴보았다. 카올린슬러리를 압밀시켜 제조한 점토층에 가솔린, 알콜, 그리고 물의 혼합액을 152 Pa하에서 접촉시켰다. 점토층내로의 유체이동은 교체된 간극유체유량을 측정함으로써, 그리고 현상학적인 관찰은 핵자기 공명상(magnetic resonance image; MRI)을 측정해봄으로 추적하였다. 또한 점토시료의 구조는 environmental scanning electron microscopy (ESEM)를 이용하여 분석하였다. 연구결과를 볼 때 가솔린만 존재시 접촉 14일 이후에도 물로 포화된 점토층내로 가솔린이 이동하지 못한 반면 gasohol 혼합체는 접촉후 단 20분이내에 점토층을 완전 통과하여 탄화수소계연료에 첨가된 알콜이 점토층내로의 이동을 한층 강화하는 것으로 나타났다. Gasohol과 접촉시 이러한 점토의 투수계수 증가는 알콜로 인해 점토의 공극구조가 붕괴되어 더 큰 공극을 형성시켰기 때문인 것으로 판단되었다. 또한 공극직경(pore diameter)이 증가함으로 gasohol이 간극수를 교체하는데 필요한 모세압력이 감소되어 gasohol이 쉽게 점토증을 이동하게 되는 것이다.

• 한국환경복원기술학회지
• /
• 제25권6호
• /
• pp.35-50
• /
• 2022

As the water shortage has become a noticeable issue due to climate change, forests play an importance role as the provider of water supply service. There is, however, little information about the relationships between the factors used in the estimation of water supply service and coarse pore fraction of forest soil which determines the potential of water supply. To find out whether there would be an amelioration in the scoring system of water supply service estimation, we examined all factors except meteorological one and additionally, analyzed 4 extra factors that might be related with coarse pore fraction of soil. A total of 2,214 soil samples were collected throughout South Korea to measure coarse pore fractions from 2015 to 2020. First, the result of average coarse pore fraction of all samples showed 32.98±6.59% which was consistent with previous studies. And the results of non-parametric analysis of variance indicated that only two of eleven factors that was used in the scoring system matched the results of coarse pore fraction of forest soils. Tree canopy coverage showed no difference among categories, and slope also showed no significance at level of 0.05 in the linear regression analysis. Additionally, the applicability of 4 extra factors were confirmed, as the result of coarse pore fractions of soil samples were different for various categories of each factor. Therefore, the scoring system of water supply service of forest should be revised to improve accuracy.

• 한국지반공학회논문집
• /
• 제39권8호
• /
• pp.29-39
• /
• 2023

흙은 간극수와 이중층수를 통해 전기적 흐름이 발생하기 때문에 간극수 및 이중층수의 연결성, 즉 포화도에 따라 전기전도도가 변화한다. 본 연구에서는 간극수 전도가 지배적인 사질토와 표면 전도 효과가 두드러진 세립토에서 포화도에 따른 전기전도도를 분석하고, 수정된 Archie의 방정식을 통해 불포화토의 전기전도도를 표면 전도와 간극수 전도의 합으로 표현하고자 한다. 4개의 전극이 설치된 플라스틱 셀에 다양한 포화도(40%-100%)와 간극률(0.45-0.82)를 갖는 시료를 조성하였으며, 간극수의 농도를 조절하기 위해 시료 조성에 사용된 간극수는 0M(증류수)-0.5M NaCl 용액을 사용하였다. 시험 결과, 사질토의 전기전도도는 포화도의 지수함수로 표현되었으며, 포화도의 지수는 간극수의 농도와 관계없이 1.93로 결정되었다. 반면 세립토의 경우, 포화도의 지수는 간극수의 농도에 따라 큰 차이를 보였다. 이는 각 간극수의 농도에서 흙의 전기전도도에 대한 표면전도의 상대적인 크기가 다르기 때문이다. 다시 말해, 포화도가 간극수전도와 표면전도에 미치는 영향이 다르며, 수정된 Archie의 방정식으로 흙의 전기전도도를 예측하기 위해서는 간극수 전도와 표면 전도에 각각 다른 포화도의 지수를 사용해야함을 의미한다.

• 한국물환경학회지
• /
• 제26권6호
• /
• pp.1000-1007
• /
• 2010

In this study, toxicity monitoring of sediments collected from 25 stations in the Geum river basin was conducted using Daphnia magna and Moina macrocopa. According to the results of acute toxicity tests (immobilization and mortality) of organic extracts of semdiments, Miho stream showed much less toxicity than Gap and Nonsan streams. In particular, significant toxicity was observed in both species for St.15 and St.16 sediment samples that passed through Deajeon city as a branch of Gap stream. For Nonsan stream, St.23 sediment showed high toxicity toward M. macrocopa. This site seemed to be affected by upper agricultural industrial complex. Additionally, M. macrocopa showed a higher sensitivity than D. magna for organic extracts of sediments. In the case of toxicity tests using sediment pore water and aqueous extracts, only pore water of St.27 sediment was toxic against D. magna. Toxicity identification evaluation showed that hydrogen sulfide was likely a major toxicant in the pore water.

• 한국산림과학회지
• /
• 제83권4호
• /
• pp.473-479
• /
• 1994

본 연구는 임지의 수저류능력을 토양공극 구분에 의한 실제 이용가능수량으로 평가하여 지속적인 수자원의 확보를 위한 기초자료를 제공할 목적으로 수행하였으며, 그 결과는 다음과 같다. 1. 조공극은 임지>임간나지>초지의 순으로 높았고, 토심이 깊을수록 전공극, 조공극, 이용가능수량은 감소하는 반면, 세공극은 점차 증가하는 것으로 나타났다. 2. 토양의 공극과 이학적 특성은 지피상태별로 표층(0~20cm)에서 고도의 유의차를 보이는 반면, 토심 20~40cm와 토심 40~60cm에서는 큰 차이가 없었다. 한편, 동일 시험구에서 표층(0~20cm)과 토심 20~40cm와는 큰 차이를 보이나 토심 20~40cm와 토심 40~60cm와는 큰 차이가 없었다. 3. 전 시험구에서 이용가능수량은 조공극과 고도의 상관관계를 나타냈다. 4. 조공극량과 토심을 이용하여 나타낸 이용가능수량으로 각 지피상태별 수저류량 추정모델을 산출할 수 있었다.

• 한국습지학회지
• /
• 제2권1호
• /
• pp.69-85
• /
• 2000

Wetlands are generally thought to be among the most fertile and productive ecosystems of the world. They provide a variety of ecological functions to the landscape. In recent years there has been considerable research activity to generate more scientific documentation on the ecological functions of wetlands. Many pollutants released to the environment settle and accumulate in the silt and mud called sediment on the bottoms of wetlands. Contaminated sediment can cause adverse effects to aquatic organism and eventually to ecological system. Sediment toxicity test with water fleas has been done by standardized preparation method of pore and elutriate water methods described in the literature for the need to protect Woopo wetlands. The results of Daphnia magna, Ceridaphnia dubla and Simocephalus sp. toxicity test were compared and discussed in terms of the relative sensitivity and discrimination abilities with both pore and elutriate water obtained from the sediments of Woopo wetlands.

• 한국농공학회지
• /
• 제45권6호
• /
• pp.144-152
• /
• 2003

Laboratory experiments were carried out to investigate the influence of pore water contamination on the treatment effect of sandy soil which was solidified by Portland cement. In the experiments, setting time of hydraulic cement that was mixed with contaminated mixing water was measured using Vicat equipment and observed the tendency of setting process with the kind of contaminants, organic or inorganic components. It was shown that organic contaminants of the mixing water affect largely on the initial setting process of hydraulic cement and inorganics, expecially heavy metals, did not affect on the initial setting process, otherwise it was appeared that setting time of the sandy soil that was contaminated with inorganic components was apparently faster than the sandy soil that did not include inorganic components even though organic concentrations was relatively low level (COD=200∼300) in the mixing water. The results of unconfined compression strength test (UCST) were well consistent with the results of Vicat equipment test.

• Membrane and Water Treatment
• /
• 제8권5호
• /
• pp.499-515
• /
• 2017

The purpose of this study was to investigate membrane fouling caused by microalgal cells in submerged membrane systems consisting of polymeric and ceramic microfiltration membranes. In this study, one polymeric (flat-sheet, pore size: $0.2{\mu}m$) and two ceramic (flat-sheet, pore size: $0.2{\mu}m$ and cylindrical, pore size: $1{\mu}m$) membranes were used. Physical cleaning was performed with water and air to determine the potential for reversible and irreversible membrane fouling. The study results showed that substantial irreversible membrane fouling (after four filtration cycles, irreversible fouling degree 27% (cleaning with water) and 38% (cleaning with air)) occurs in the polymeric membrane. In cleaning studies performed using water and air on ceramic membranes, it was observed that compressed air was more effective (recovery rate: 87-91%) for membrane cleaning. The harvesting performance of the membranes was examined through critical flux experiments. The critical flux values for polymeric membrane with a pore size of $0.20{\mu}m$ and ceramic membranes with a pore size of $0.20{\mu}m$ and $1{\mu}m$ were ${\leq}95L/m^2hour$, ${\leq}70L/m^2hour$ and ${\leq}55L/m^2hour$, respectively. It was determined that critical flux varies depending on the membrane material and the pore size. To obtain more information on membrane fouling caused by microalgal cells, the characterization of the fouled polymeric membrane was performed. This study concluded that ceramic membranes with a pore size of $0.2-1{\mu}m$ in the submerged membrane system could be efficiently used for microalgae harvesting by cleaning the membrane with compressed air at regular intervals.

• 한국지반공학회:학술대회논문집
• /
• 한국지반공학회 2004년도 춘계학술발표회
• /
• pp.274-281
• /
• 2004

In this paper, the existing Stokoe type torsional shear equipment is modified to saturate the specimen and measure excess pore water pressure during undrained testing. Two types of sands, Geumgang and Toyoura sands, were collected and TS tests were performed at various densities drainage conditions, and confining pressures. The cyclic threshold shearing strains were estimated based on the variations of shear modulus, material damping ratio and pore pressures with loading cycles. The effects of relative density, confining pressure, and drainage condition on the cyclic threshold shearing strains were investigated.

• Coupled systems mechanics
• /
• 제3권2호
• /
• pp.233-245
• /
• 2014

Coupled finite element analysis is carried out to study the effect of degree of saturation on the vertical displacements and pore water pressures simultaneously by developing a FORTRAN90 code. The finite element formulation adopted in the present study is based upon Biot's consolidation theory to include partially saturated soils. Numerical methods are applied to a two-dimensional plane strain strip footing (flexible) problem and the effect of variable degree of saturation on the response of excess pore water pressure dissipation and settlement of the footing is studied. The immediate settlement in the case of partly saturated soils is larger than that of a fully saturated soil, the reason being the presence of pore air in partially saturated soils. On the other hand, the excess pore water pressure for partially saturated soil are smaller than those for fully saturated soil.