• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2010년도 추계 학술발표회
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• pp.1190-1200
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• 2010

A method was developed to determine resilient modulus for crushed rock-soil mixtures whose usage has been increased recently without engineering specifications. The method is based on the subtle different modulus called nonlinear dynamic modulus and was lately implemented in residual soils and engineered crushed-stones. Hereby. the same method was expanded to crushed rock-soil mixtures containing as large grain diameter as 300mm. The method utilize field direct-arival tests for the determination of maximum Young's modulus, and a large scale free-free resonant column test, which is recently developed to is capable to test as large grain diameter as 25mm, for modulus reduction curves. The prediction model of resilient modulus was evaluated for crushed rock-soil mixtures of a highway construction site at Gimcheon, Korea.

• Geomechanics and Engineering
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• 제8권5호
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• pp.675-685
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• 2015

Weathering is the breaking/cutting down process of rocks due to physical and chemical processes in natural as well as artificial environment including $CO_2$ injection for storage in the sediment, or natural resource recovery process. This study suggests an alternative method to estimate the degree of weathering for granites. A series of laboratory and field experiments are performed to measure electrical resistivities on various rock samples experienced different degrees of weathering and their residual soils under different saturation conditions. It is found that the normalized electrical resistivity increases with a decrease in water absorption and the saturation. Simple boundaries are suggested to identify the weathering degree of granites, based on limited data. Field test results for three sites confirm that the suggested method could be estimated well the degree of weathering of granites compared with the other methods suggested previously. Although further research is required, this study suggests that an electrical resistivity could be an effective approach to estimate the degree of weathering of granites compared with the other methods suggested previously.

• 한국지하수토양환경학회:학술대회논문집
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• 한국지하수토양환경학회 2002년도 추계학술발표회
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• pp.75-80
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• 2002

Enormous volumes of mining wastes from the abandoned and closed mines are disposed without a proper treatment at Southeastern part of Kangwon Province. Erosion of these wastes contaminates soil, surface water, and sediments with heavy metals. Objectives of this research were to fractionate heavy metals in the mine waste and to assess the potential S. P. A. G.(Soil Pollution Assesment Guidance) of each metal fraction. Mine wastes analyzed for physical and chemical properties. pH of wastes ranged from 3.3 to 8.0. Contents of total N and loss on ignition matter were in the ranges of 0.2~5.6%, and 0.8~15.3%, respectively. Heavy metals in the wastes were higher in the coal mines than those in the other mine wastes. Total concentrations of metals in the wastes were in the orders of Pb > Zn > Cu > Cd, exceeded the corrective action level of the Soil Environment Conservation Law and higher than the natural abundance levels reported from uncontaminated soils. Relative distribution of heavy metal fractions was residual > organic > reducible > carbonate > adsorbed, reversing the degree of metal bioavailability. Mobile fractions of metals were relatively small compared to the total concentrations. Soil Pollution Assesment Guidance(SPAG) values were ranged from 0.08 to 9.14 based on labile fraction of metal concentrations. SPAG values of labile concentration were lower than those of total concentration.

• 한국지하수토양환경학회지:지하수토양환경
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• 제16권6호
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• pp.95-105
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• 2011

Total extraction method and environmental standards for heavy metals in soils were revised in regulation recently. In case of Area 3, as the law amended, the soil pollution level has gone up to 4 to 13 times higher depending on the type of heavy metal. In this study, it compares the properties of heavy metals of soil by sequential extraction and total extraction methods depending on the analysis method, using the soil around mine. In case of arsenic, the soil pollution level has gone up to 4 times higher, but 6 to 10 times in the sample soil. Also, according to the results of portability evaluation depending on the type of existence form of heavy metal it exists as residual form in mine waste rock, which is less likely to move, while it exists as migrated form in tailing. Therefore, it should be considered to evaluate the soil pollution and decide the contaminated bounds depending on the existence form of heavy metals on soil to restore the polluted soil.

• 한국농공학회논문집
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• 제46권6호
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• pp.61-69
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• 2004

The aim of the work described in this paper was to confirm the application of the equation of the soil-water characteristic curves on an unsaturated soil. A series of suction test for unsaturated soils was conducted on the selected 4 kinds of soil using modified pressure extractor apparatus. And it was carried out to analyse The experimental parameters which can be describe the soil-water characteristics, were determined by using the data obtained from the experiment. From the results, it was found that The matric suction varied according to the grain size distribution, amount of fine grain particles and void ratio. Also it was found that the residual degree of saturation was decreased with in crease of the void ratio, but the pore size distribution index and air entry value were increased with in crease of the void ratio. And The application of the soil-water characteristic curve equation was confirmed for the various conditions and the various state by the comparison between the measured degree of saturation and the predicted degree of saturation.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2008년도 춘계학술대회 논문집
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• pp.1695-1704
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• 2008

The problems associated with constructing high-speed concrete track embankments over soft compressible soil has lead to the development and/or extensive use of many of the ground improvement techniques used today. Drains, surcharge loading, and geosynthetic reinforcement, have all been used to solve the settlement and embankment stability issues associated with construction on soft soils. However, when time constraints are critical to the success of the project, owners have resorted to another innovative approach. Especially, the design criteria of residual settlement is limited as 30mm for concrete track embankment, it is very difficult to satisfy this standard using the former construction method. Pile net method consist of vertical columns that are designed to transfer the load of the embankment through the soft compressible soil layer to a firm foundation and one or more layers of geosynthetic reinforcement placed between the top of the columns and the bottom of the embankment. This paper will present the guidelines for the design of pile net method to supported embankments. These guidelines were developed based on a review of current design methodologies and a parametric study of design variables using numerical modeling.

• Applied Biological Chemistry
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• 제21권3호
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• pp.185-192
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• 1978

제초제((除草劑)중 국내에서 많이 사용되는 nitrofen(NIP, TOK), butachlor (Machete) 및 alachlo (Lasso의 잔류성(殘留性)을 조사하기 위하여 가수분해를 거치지 않고 전자(電子)포획검출기가 부설된 깨스크로마토그래피로 분석하는 방법을 확립시킨 후 이들 제초제를 유지(油脂)작물인 유채(油菜), 대두(大豆) 및 수도(水稻)의 재배포장에 사용(施用)하였을 때의 잔류량(殘留量)을 분석하였다. 그 결과 세가지 제초제(除草劑)는 사용후 2주일만에 급격히 감소하였으며 그 이후에는 점차적으로 감소하여 10%수준에 도달하였다. 그러나 유지(油脂)원료인 세 작물의 종자(種子)에는 분석한계치(分析限界値)안에서 전혀 검출(檢出)되지 아니하였다.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2008년도 추계 학술발표회
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• pp.966-973
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• 2008

In recent, the collapses of cut-slope is gradually increased due to the heavy rains accompanied by typhoon. Specially, many cut-slope failures and landslides was happened to Goheung, Yeosu, Suncheon region, Jeonranamdo in the middle of September 2007. The slope of investigation is width 20 m, height 22 m, and the circular failure was occurred. The parent rocks of the slope are pyroclastic rock, namely andesite, andesitic tuff et al. and the weathering grade is completely weathered to residual soils owing to rapid weathering process and has the existence of fault zone and mafic dyke. Also, lots of extension cracks are presented and the hydrologic condition is very deteriorated. As a result of the limit equilibrium analysis, the safety factor is 1.09(in dry season) and 0.64(in wet season). For the stabilization of the cut-slope, we decided to use the retaining wall, anchors and drainage apparatus.

• Geomechanics and Engineering
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• 제16권6호
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• pp.635-642
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• 2018

Braced excavation systems are commonly required to ensure stability in construction of basements for shopping malls, underground transportation and other habitation facilities. For excavations in deposits of soft clays or residual soils, stiff retaining wall systems such as diaphragm walls are commonly adopted to restrain the ground movements and wall deflections in order to prevent damage to surrounding buildings and utilities. The ground surface settlement behind the excavation is closely associated with the magnitude of basal heave and the wall deflections and is also greatly influenced by the possible groundwater drawdown caused by potential wall leakage, flow from beneath the wall, flow from perched water and along the wall interface or poor panel connections due to the less satisfactory quality. This paper numerically investigates the influences of excavation geometries, the system stiffness, the soil properties and the groundwater drawdown on ground surface settlement and develops a simplified maximum surface settlement Logarithm Regression model for the maximum ground surface settlement estimation. The settlements estimated by this model compare favorably with a number of published and instrumented records.

• Nuclear Engineering and Technology
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• 제11권1호
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• pp.47-54
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• 1979

수도(水稻)에 의한 $^{65}$ Zn 표지 및 비표지 아연비료의 잔류(殘留) 효과의 포장실험 결과를 요약하면 다음과 같다. 수량면에서 본 아연비료의 잔효(殘效)는 약간 있었다. 수량에 미치는 아연시비법(施肥法)의 영향을 보면 아연 건층시비가 포층시비 보다 효과가 컸다. 아연 시비 수준별로 본 수량은 5kg Zn/ha 전층 시비가 10, 20kg Zn/ha 건층시비 보다 좋았다. 아연비료 형태별로 수량을 비교해 보면 $^{65}$ ZnSO$_4$ 가 Urea-$^{65}$ Zn 복합비료 보다 좋았다. 이와 같은 경향은 1차년도 실험 결과와 같았다. 수도체(水稻體)의 아연 전 흡수량은 유기물 첨가토양(처리 2와 8)과 Urea-$^{65}$ Zn 복합비료 시용구에서는 전년도 보다 현저하게 증가되었다. 수도체의 % Zndff값은 전년도에 얻어진 값 보다 훨씬 감소되었다. 수도체의 비료 아연 흡수량은 대부분의 아연 처리구에서 전년도 보다는 약간 감소되었으나 유기물 시용토양에 아연을 전층시비했을 때와 Urea-$^{65}$ Zn 복합비료 시용구에서는 전년도의 값 보다는 오히려 증가되었다. 아연 전층시비법은 표층시비법 보다 수도체의 비료 아연 흡수량은 많았다. 수도체의 전아연 흡수량에 대해서 비료에 유래된 아연의 기여율은 4.6%-24.3% 범위하였다. 5kg Zn/ha 수준에서 $^{65}$ Zn 표지 아연 비료의 이용 효율은 0.213%-0.58%였다.