• 한국농공학회논문집
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• 제49권4호
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• pp.63-70
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• 2007

The soil samples used in this study were prepared with the residual granite soils passed through the #4 sieve and obtained from Pocheon in Gyeonggi-Ki do. Specifically, five types of samples were prepared. Sample A which is a natural state soil was classified as SM according to the uses. Samples of B, C, D, and E were prepared by mixing Sample A with bentonite and were classified as SC according to the uses. The plasticity indexes of samples B, C, D, and E were 15, 25, 30, and 40, respectively. The specimens, whose dimensions are 100mm by 127.5mm, were prepared by A method of ASTM D 698 with the Proctor mold. In experiments, the loading with the 1%/min was applied. Four different disk diameters, 13mm, 26mm, 38mm, and 52mm were used in the Improved Unconfined Penetration (IUP) tests. To compare the tensile strengths, the split tensile tests were also conducted on the same specimens used for the IUP tests. To find out the effects of moisture contents, plasticity Index of specimens on the tensile strength, six different water contents were used for making a specimen.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2008년도 추계 학술발표회
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• pp.1098-1108
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• 2008

Batch type and column type experiments were performed in order to predict adsorption and movement within soil. Clay minerals montmorillonite and kaolinite were respectively added to paraquat which is a cationic compound with long residual time, 2,4-D which is an anionic compound with relatively short residual time and napropamide which is an amphoteric compound. Therefore, it is very important to determine the movements of toxic pollutants in the ground soil to establish measures to prevent soil grounds contamination and to restore contaminated soils effectively, because contamination of soil is getting severe due to these toxic wastes, industrial waste water, and agricultural chemicals, etc. Therefore, in this study, we have carried out column and batch experiments by using general toxic organic compounds as test samples in order to restore contaminated soils effectively as well as to prepare a basic data to develop absorbents that will remove various toxic organic compounds, with a grandiose purpose to prevent contaminations of soil and grounds due to various toxic organic compounds.

• 한국의류산업학회지
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• 제13권3호
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• pp.425-431
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• 2011

The purpose of this study was to investigate washing effects according to the rinsing conditions and the characteristics of soiled fabrics. In this study rinsing conditions including rinsing cycle, time, temperature, and bath ratio were examined. The foamability of rinsing bath was also examined. The quantity of LAS in the rinsing bath and extracts of test fabrics was analyzed after washing and rinsing, respectively. The results of these experiments were as follows: The washing effects of soiled fabrics were varied from the kinds of soils and rinsing conditions. The removal of soils from fabrics was increased by the first rinsing after washing effectively. The priorities of rinsing conditions were rinsing temperature> rinsing time > rinsing cycles> references. Foamability was result from residual LAS in rinsing bath and fabrics extracts after rinsing. The residual quantity of LAS was references > rinsing cycles> rinsing time> rinsing temperature, which shown rinsing temperature was the most efficient factor of the rinsing performance.

• 터널과지하공간
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• 제7권1호
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• pp.31-38
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• 1997

Residual shear strength should be taken into consideration as well as peak one when analysing stability of slopes constituted by weathered rock or overconsolidated soils since such materials could be subjected to progressive failure mechanism. When landslide of a slope is related to progressive failure phenomenon, the failure might occur even though shear strength of the slope materials does not reach their residual shear strength over the whole slip surface. Therefore, stability of the slope concerned may be overstimated or underestimated when using only its peak or residual shear srength parameters. Mechanical description for progressive failure phenomenon is given by Bjerrum(1967). In parameters. Mechanical description for progressive failure phenomenon is given by Bjerrum(1967). In this study, his theory has been extended to estimate the distance of failed zone for a plane slope and the results calculated by this extended equatio has been compared with that obtained by numerical modelling using FLAC. In addition, stress state on the slip surface has been, in detail, analysed to understand failure mechanism when a limited progressive failure occurs. Effects of mechanical and hydraulic factors on progressive failure have also been analysed.

• 약학회지
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• 제18권1호
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• pp.29-38
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• 1974

In order to study the residual amounts of absorbed organochlorine pasticides in vegetables, heptachlor and endrin were sprayed 2,4 and 6kg per 10a., respectively, before sowing the seeds in the station. The experiemental study is primarily concerned with the absorption in lettuce nad garland chrysanthemum. The absorption of each pesticide into lettuce and garland chrysanthemum, and residual pesticides in soil by timne have been analyzed by the gas chromtographic method, and the ratio of residual pesticides in vegetablesand soil were estimated. Heptachlor, heptachlor epoxide and endrin in lettuce nad garland chrysanthemum at the market in Seoul area hvae also analyzed and found extremely low level of pesticides in comparison with the level in above experimental vegetables as well as same vegetables in Japan.

• 한국토양비료학회지
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• 제40권2호
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• pp.164-171
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• 2007

공단인근의 여러 중금속이 복합적으로 오염된 토양에서 중금속의 존재형태와 미나리 중 함량과의 관계를 평가하기 위하여 미나리 재배토양, 농수로 퇴적 저니토 및 대조토양과 동일지점에서의 미나리를 채취하여 분석 검토하였다. 토양의 중금속 총함량 중 Cd, Cu 및 Ni의 평균농도가 Kloke (1979)가 제안한 중금속의 허용한계치를 초과하였다. 중금속별 토양 내 주된 존재형태는 Cd이 치환태였고, 다른 중금속 (Cu, Zn, Ni 및 Pb)은 Fe-Mn 산화물 및 잔류 형태로 나타났다. 재배토양과 농수로 저니토의 형태별 함량에 의하여 환산된 잠재적인 중금속 이동계수는 Cd>Zn>Ni>Cu>Pb 순이였고, 특히 Cd의 경우 대조토양에 비하여 매우 높은 것으로 알수 있었다. 토양의 Cd 전함량과 토양 내 이동성이 높은 치환성 및 Fe-Mn 산화물 분포비율과는 정의 상관, 이동성이 낮은 잔류태와는 부의 상관을 보였다. 미나리 부위별 중금속은 대부분이 뿌리에 축적되었으며, 지상부로의 이행성은 Cd과 Zn가 줄기에서 높았고, Cu와 Ni 함량은 오히려 잎에서 높았다. 토양 중금속 중 Cd, Cu 및 Ni의형태별 함량과 미나리 중 함량과 관련성이 높았고, 특히 치환성 Cd과 Ni 함량은 미나리 중 함량과 고도의 정의상관을 보였다.

• 한국해양공학회지
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• 제24권5호
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• pp.39-47
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• 2010

In this paper, a total stress analysis method for gravity quay walls is suggested. The method can evaluate the displacement of the quay walls considering the effect of excess pore pressure developed in backfill soils. This method changes the stiffness of backfill soils according to the expected magnitude of the excess pore pressure. For practical application, evaluation methods are suggested for determining the excess pore pressure ratio developed in the backfill soils and the backfill stiffness that corresponds to the excess pore pressure ratio. This method is important in practical applications because the displacement of the quay walls can be evaluated by using only the basic input properties in the total stress analysis. The applicability of the suggested method was verified by comparing the results of the analysis with the results of 1-g shaking table tests. From the comparison, it was found that the calculated displacements from the suggested method showed good agreement with the measured displacements of the quay walls. It was also found that the excess pore pressure in backfill soils is a governing influence on the dynamic behavior of quay walls.

• Geomechanics and Engineering
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• 제33권5호
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• pp.453-462
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• 2023

Intermediate Geomaterials (IGMs) are natural formation materials that exhibit the engineering behavior (strength and compressibility) between soils and rocks. The engineering behavior of such material is highly unpredictable as the IGMs are stiffer than soils and weaker/softer than rocks. Further, the characterization of such material needs exposure to both soil and rock mechanics. In most conventional designs of geotechnical structures, the engineering properties of the IGMs are either aligned with soils or rocks, and this assumption may end up either in an over-conservative design or under-conservative design. Hence, many researchers have attempted to evaluate its actual engineering properties through laboratory tests. However, the test results are partially reliable due to the poor core recovery of IGMs and the possible sample disturbance. Subsequently, in-situ tests have been used in recent years to evaluate the engineering properties of IGMs. However, the respective in-situ test finds its limitations while exploring IGMs with different geological formations at deeper depths with the constraints of sampling. Standard Penetration Test (SPT) is the strength-based index test that is often used to explore IGMs. Moreover, it was also observed that the coefficient of variation of the design parameters (which represents the uncertainties in the design parameters) of IGMs is relatively high, and also the studies on the probabilistic characterization of IGMs are limited compared with soils and rocks. With this perspective, the present article reviews the laboratory and in-situ tests used to characterize the IGMs and explores the shear strength variation based on their geological origin.

• 한국지반환경공학회 논문집
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• 제14권5호
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• pp.41-47
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• 2013

일반적으로 입도분포가 양호하며 조밀한 흙은 공학적 성질이 우수하다. 불포화토의 공학적 성질, 즉 전단강도, 압축성, 투수성 등의 거동은 흙의 함수특성곡선과 밀접한 관계가 있다. 따라서 사질토의 입도분포 및 다짐상태와 관련있는 균등계수와 공극율이 그 흙의 함수특성곡선에 미치는 영향을 연구하는 것은 중요하다. 본 연구에서는 6개의 사질토 시료에 대하여 템페셀을 사용하여 함수특성곡선시험을 하였다. 시험결과를 Fredlund and Xing 모델식으로 최적화하여 모델식의 매개변수를 구하였고, 시료의 균등계수와 공극율이 매개변수에 미치는 영향을 조사하였다. 시료의 잔류흡수력은 시료의 공극율이 작을수록, 그리고 균등계수가 클수록 증가하였으며, 함수특성곡선의 최대경사는 시료의 균등계수와 상관없이 공극율이 작을수록 완만해짐을 알 수 있었다.

• 한국지반공학회논문집
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• 제19권2호
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• pp.27-38
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• 2003

본 연구에서는 불포화토의 전단강도 특성과 이를 예측하는 모델에 대해 다루었다. 특히, 순연직응력(net normal stress)이 흙수분 특성곡선에 미치는 영향과 불포화토의 전단강도 발현에 미치는 영향에 대해 중점적으로 연구하였다. 이를 위해서 국내에 산재해 있는 화강풍화잔적토를 시료로 하여 불포화삼축압축 시험과 SWCC 시험 등을 실시하였으며, 특히, 순연직응력을 일정하게 유지시킨 상태에서 SWCC를 구할 수 있게 끔 기존의 장비를 개량하였다. 불포화토의 전단강도 시험결과와 기존의 강도예측모델에 의해 예측된 강도포락선을 비교해 본 결과, 흙수분 특성곡선과 흡인력 (matric suction)을 한 축으로 하는 강도포락선의 기울기가 순연직응력에 따라 변화함을 발견할 수 있었다. 따라서, 보다 정확하게 불포화토의 전단강도 포락선을 묘사하기 위해서는 흡인력에 미치는 순연직응력의 영향이 고려되어야 하는 것으로 나타났다. 본 논문에서는 기 언급한 내용에 근거하여 수정된 불포화토 전단강도 예측모델을 제안하였다.