• 한국환경과학회지
• /
• 제4권4호
• /
• pp.379-386
• /
• 1995

합성 Pyrethroid계 pennethrin[3-phenoxybenzyl(1RS)-cis,trans-3-(2,2-dichlorovinyI)-2,2-dimethylcyclopropanecarboxylate]은 直接接觸 殺蟲劑로서, 哺乳動物에는 매우 底毒性이므 로 使用훌이 增加되고 있다. 따라서 土훌中 pennethrin의 動態를 豫願할 必要가 있다. Permethrin을 GC-ECD로 分析하였으며, cis-pennethrin은 32.5%였고 trans-pennethrin은 67.4%였다. Commerce silty clay loam 土壤에서 Koc값은 CIS 및 trans-pennethrin이 각각 938 및 877였다. 土壤 컬럼$(5.4 cm i.d. \times 26 cm length)$을 利用한 溶脫實廣올 하였다. 3배의 pore 부피에 해당하는 물로 cis-pennethrin올 浸出할 경우, 處理된 土壞層에 74.00%였고 6.10%만 아래충으로 移動되었으며,0.07%의 澈훌만 漫出水로 浸出되었다. Pennethrin은 土황에 강하게 吸훌되기 때문에, 土壤 column에서의 漫出量도 매우 적었다. 따라서 自然系에서의 漫出(Leaching) 및 유거(Runoff)농도는 매우 낮을 것으로 據測된다.

• 한국토양비료학회지
• /
• 제42권6호
• /
• pp.454-459
• /
• 2009

전북 부안군 소재 계화도간척지 시험포장에서 토양의 염류가 논토양의 투수성에 미치는 영향을 알고자 염농도가 높은 지점과 낮은 지점을 대상으로 시료를 채취하여 토양의 물리 화학성을 조사한 결과는 다음과 같다. 시험토양은 포화침출액 전기전도도($EC_{e}$)가 고염지 표토 $25.2dS\;m^{-1}$, 고염지 심토 $37.8dS\;m^{-1}$, 저염지 표토 $3.0dS\;m^{-1}$, 저염지 심토 $3.4dS\;m^{-1}$로 시험토양을 염류토양 분류기준에 의거 분류한 결과, 고염지 표토는 saline soil, 고염지 심토는 saline-sodic soil이었고 저염지 표토 및 심토는 일반 토양(normal soil)에 해당되었다. 토주실험 결과 저염지 표토의 포화수리전도도 (Ksat)는 $0.623cm\;hr^{-1}$이었으나, 고염지 표토에서는 용출수의 하향이동이 거의 일어나지 않았다. 고염지 표토를 토양 무게에 대하여 1:2의 비율로 증류수, 1N NH4OAc, 0.1eq L-1oxalic acid로 연이어 세척하여 수용성 및 치환성 이온을 부분 제거하고 컬럼에 충전하여 포화수리전도도를 측정한 결과, $K_{sat}$값은 세척전에 투수가 거의 일어나지 않았던 것에 비하여 크게 증가하여 $0.68cm\;hr^{-1}$을 나타내었다. 세척비율 1:3과 1:7에서 같은 방법으로 포화수리전도도를 측정한 결과 $K_{sat}$값은 각각 $0.71cm\;hr^{-1}$, $0.73cm\;hr^{-1}$을 나타내었고 토양에 대한 희석요인이 증가할수록 $K_{sat}$값은 더 증가하는 경향을 나타냈다. 고염지 표토 토양을 $1N\;NH_4OAc$로 1시간 진탕 세척하여 수용성 및 치환성 양이온의 대부분을 제거한 후 컬럼에 충전하여 포화수리전도도를 측정한 결과, $K_{sat}$값은 $0.23cm\;hr^{-1}$으로 크게 증가하였고, 수용성 및 치환성 양이온을 제거한 고염지 표토 토주의 하단에 NaCl용액을 농도별로 상향 포화시켜 처리한 후 포화수리전도도를 측정한 결과 $K_{sat}$값은 NaCl 처리 농도별로 $0.13{\sim}0.15cm\;hr^{-1}$을 나타내었으며 NaCl의 처리 농도가 증가함에 따라 $K_{sat}$값은 더 낮아지는 경향을 보였다.

• 한국환경농학회지
• /
• 제15권4호
• /
• pp.464-471
• /
• 1996

Commerce silty clay loam 토양에서 제초제 trifluralin의 용탈을 조사하였다. Trifluralin의 Koc값은 875이었다. 토양 컬럼(5.4 cm i.d. ${\times}$ 26 cm length)을 이용한 용탈실험에서, 3배의 pore부피에 해당하는 물로 trifluralin을 침출 할 경우, 토양 층에는 99.993%이었고, 0.007%의 미량만 침출수로 침출 되었다. 야외포장 실험에서는 미국 Louisiana Baton Rouge에 있는 포장에 trifluralin을 1683g/ha 살포하였다. 처리 31일 후, 0-60cm 토양 층에 있는 trifluralin 전체 량의 96.9%가 0-10cm 토양 층에 분포되었다. 또한, 62일 후 1m 및 2m 지하수에서 trifluralin의 농도는 0.04-0.08ng/mL이었다. 이는 미국 EPA의 음용수 중 trifluralin의 허용농도인 2.0ng/mL보다 낮았다. Trifluralin은 토양에 강하게 흡착되었기 때문에 토양 column 및 야외 포장에서의 침출량은 매우 적었으며, 토양 column 및 야외 포장에서의 결과는 일치하였다.

• 한국지반공학회논문집
• /
• 제24권9호
• /
• pp.13-21
• /
• 2008

분배성 추적자 시험법은 LNAPLs(light nonaqueous phase liquids)로 오염된 지반을 조사하는데 아주 유용한 방법이다. 하지만 토양 내 유기물질로 흡착되는 분배성 추적자는 잠재적으로 분배성 추적자 시험법의 정확성에 영향을 끼칠 수 있다. 연구 결과, 추적자의 액상-LNAPL 간 분배 계수는 선형 관계를 보였다. 토양의 흠착능력을 평가하기 위해 흡착 등은 실험을 수행한 결과, Freundlich 흡착 등은 양상과 거의 일치하였고, 추적자의 흡착 정도는 토양 내 유기물질 함량이 증가함에 따라 증가하였다. 또한, 토양 유기물의 흡착능에 따른 잠재적 영향을 판단하고, 추적자 시험법에 의한 LNAPLs 예측의 오차를 수정하기 위해 서로 다른 유기물 함량을 가진 4개의 컬럼 실험을 수행하였다. 컬럼 실험 결과, 오염물질이 없더라도 주문진 표준사와 유기물질이 섞인 컬럼에서는 추적자의 분리 현상이 발생하였다. 오염물질로 케로진을 주입한 이후에 다시 추적자 시험법을 수행하여 파괴곡선을 구한 결과, 토양 유기물질에 대한 추적자의 흡착으로 인해 추적자의 지연계수(R)가 커졌고 LNAPLs의 오염도가 과대평가 되었다. 또한 컬럼 실험 결과를 바탕으로 유기물 함량과 LNAPLs의 예측도 사이의 관계식을 제안하였다.

• 한국지반공학회:학술대회논문집
• /
• 한국지반공학회 2010년도 추계 학술발표회
• /
• pp.1201-1212
• /
• 2010

In order to investigate on the effect of stabilization methods for rice paddies contaminated by heavy metals, a series of lab-scale model test was carried out by applying the characteristics of submerged Paddy soil. To perform the lab-scale model test, columns were made by acrylic with the dimension of diameter=10cm, thickness=0.5cm and were filled with soils which was contaminated were mixed with stabilization agents(lime stone 5% and steel refining slag 5% respectively). To manipulate the reduction condition, soils in the columns were submerged with distilled water. And then soil water and subsurface water in each column were sampled in the regular term and analysed the various physical and chemical properties.

• 한국콘크리트학회:학술대회논문집
• /
• 한국콘크리트학회 1998년도 가을 학술발표대회 논문집(III)
• /
• pp.603-608
• /
• 1998

This study was performed to examine the effect of time dependent properties on RC columns in subway structures subjected to high filled soil layer. By using Program TCC which is a modified version of CPF for the present purpose, a typical column in subway structure was analyzed. Four different model equations for predicted time dependent concrete properties(ACI, CEB-FIP, Bazant & Panula and Korea Bridge Specification) was employed, and the results were compared. It was found that a relevant creep coefficient is recommended to be 1.0 for designing columns in subway structure, and the sol filling work would be performed at least 3 months later after the concrete casting in order to ensure durability by reducing the negative effect of concrete time dependent properties.

• Geomechanics and Engineering
• /
• 제9권4호
• /
• pp.415-426
• /
• 2015

Researches have been done to discover ways to strengthen peat soil deposits. In this model study, fibrous peat that is the most compressible types of peat has been reinforced with precast peat columns stabilized with ordinary Portland cement and polypropylene fibres. Rowe cell consolidation tests as well as plate load tests (PLTs) were conducted on various types of test samples to evaluate the strength and deformation of untreated peat and peat reinforced by various types of columns. PLTs were conducted in a specially designed and fabricated circular steel test tank. The compression index ($C_c$) and recompression index ($C_r$) of fibrous peat samples reduced considerably upon use of precast columns. Also, PLT results confirmed the results obtained from Rowe cell tests. Use of polypropylene fibres added to cement further decreased ($C_c$) and ($C_r$) and increased load bearing capacity of untreated peat. Finite element method (FEM) using Plaxis 3D was carried out to evaluate the stress distributions along various types of tested samples and also, to compare the deformations obtained from FEM analysis with the actual maximum deformations found from PLTs. FEM results indicate that most of the induced stresses are taken on the upper portion of tested samples and reach their maximum values below the loading plate. Also, a close agreement was found between actual deformation values obtained from PLTs and values resulted from FEM analysis for various types of tested samples.

• Structural Engineering and Mechanics
• /
• 제31권5호
• /
• pp.545-566
• /
• 2009

Bridge columns are subjected to combined actions of axial force, shear force and bending moment during earthquakes, caused by spatially-complex earthquake motions, features of structural configurations and the interaction between input and response characteristics. Combined actions can have significant effects on the force and deformation capacity of RC columns, resulting in unexpected large deformations and extensive damage that in turn influences the performance of bridges as vital components of transportation systems. This paper evaluates the seismic response of three prototype reinforced concrete bridges using comprehensive numerical models that are capable of simulating the complex soil-structural interaction effects and nonlinear behavior of columns. An analytical approach that can capture the shear-flexural interacting behavior is developed to model the realistic nonlinear behavior of RC columns, including the pinching behavior, strength deterioration and stiffness softening due to combined actions of shear force, axial force and bending moment. Seismic response analyses were conducted on the prototype bridges under suites of ground motions. Response quantities of bridges (e.g., drift, acceleration, section force and section moment etc.) are compared and evaluated to identify the effects of vertical motion, structural characteristics and the shear-flexural interaction on seismic demand of bridges.

• Interaction and multiscale mechanics
• /
• 제2권4호
• /
• pp.397-411
• /
• 2009

The effect of soil-structure interaction on a simple single storeyed and two bay space frame resting on a pile group embedded in the cohesive soil (clay) with flexible cap is examined in this paper. For this purpose, a more rational approach is resorted to using the three dimensional finite element analysis with realistic assumptions. The members of the superstructure and substructure are descretized using 20 node isoparametric continuum elements while the interface between the soil and pile is modeled using 16 node isoparametric interface elements. Owing to viability in terms of computational resources and memory requirement, the approach of uncoupled analysis is generally preferred to coupled analysis of the system. However, an interactive analysis of the system is presented in this paper where the building frame and pile foundation are considered as a single compatible unit. This study is focused on the interaction between the pile cap and underlying soil. In the parametric study conducted using the coupled analysis, the effect of pile spacing in a pile group and configuration of the pile group is evaluated on the response of superstructure. The responses of the superstructure considered include the displacement at top of the frame and moments in the superstructure columns. The effect of soil-structure interaction is found to be quite significant for the type of foundation used in the study. The percentage variation in the values of displacement obtained using the coupled and uncoupled analysis is found in the range of 4-17 and that for the moment in the range of 3-10. A reasonable agreement is observed in the results obtained using either approach.

• 한국지하수토양환경학회:학술대회논문집
• /
• 한국지하수토양환경학회 1998년도 공동 심포지엄 및 추계학술발표회
• /
• pp.201-205
• /
• 1998

Leakage of hydrocarbon compound from underground storage tank has been a significant issue to the hazard of environmental contaminants. It is therefore necessary to develop the measurement technique of hydrocarbon compound concentration. In this study, the possibility of TDR application to measure concentration of hydrocarbon compound, especially diesel, in a sandy soil was investigated. Experiments were conducted in two different conditions. The first one was to measure the resistances of the soil columns packed according to the various ratios of tab water and diesel content in the total voids. The other was to measure the resistance of the soil under the flow condition where diesel oil was allowed to infiltrate into the KCl-saturated soil column. The experimental results showed that there exists a significant relationship between oil% and TDR-measured resistance. This suggests that TDR can be an effective device to measure the concentration of hydrocarbon compound in a soil.