• Magazine of the Korean Society of Agricultural Engineers
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• v.20 no.4
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• pp.4799-4804
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• 1978

In order to investigate the effect of delayed compaction on the strength of the lime soil mixtures, labroatory test with two kind of soils was performed at four levels of lime content, at five levels of water content, and at six love's of delayed times. The results are summarized as follows; 1. Maximum dry density and optimum moisture content decreased with increase of the delayed times. The decreasing rate of those values at the earlier delayed time were large, and those values showed almost constant after about four hours of delayed time. 2. According to the increase of the delayed time, the decreasing rate of maximum dry density and optimum moisture content was large ia S-2 sampl, but was a little in S-1 sample. 3. Unconfined compressive strength of lime soil mixtures decreased with the increase of the delayed time, and the decreasing rate of its strength increased with the increase of the lime content. 4. Water content corresponding to the maximum strength was a little higher than the optimum moisture content along the increase of lime content and delayed time but its value was large in fine soil.

• Proceedings of the Korean Geotechical Society Conference
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• 2006.03a
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• pp.1126-1131
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• 2006

This study is part of the project that develops the permeable preactive barrier to be applied in a landfill. The geotechnical applicability of the permeable preactive barrier that filters the leachate from the landfill was evaluated. Dry specimens were made using a mixture of sand, loess and bentonite. A series of experiments are performed to determine the unconfined compressive strength and permeability of various mixing ratio of bentonite, loess, and sand. The laboratory test indicate that the optimum-mixing ratio that satisfied the regulation of unconfined compressive strength(490kPa) and coefficient of permeability$(10^{-3}\sim10^{-4}cm/s)$ of the landfill was when the ratio of sand and loess was 8:2 with bentonite content of 2%. The permeable preactive barrier is different from an impermeable barrier in that it permits a limited diffusion of the leachate, which will be directly purified biologically and chemically in the landfill.

• Journal of the Korean GEO-environmental Society
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• v.14 no.6
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• pp.31-38
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• 2013

This study carried out fundamental study on the forest road pavement method of cementing the ground using the compaction equipment after laying by mixing with eco-friendly stabilizer, natural soil and water. Target strength of pavement was set to 2.0MPa and the specimen was produced per mixing ratio of cement, kinds of natural soil and curing period to evaluate the durability and unconfined compressive strength. Unconfined compressive strength test was conducted to compare strength by producing the test specimen mixing environment-friendly cement as well as the test specimen mixing cement with the same mixing ratio. To evaluate the durability, surface abrasion test and water flow resistance test were conducted. In addition, SB and GB tests were conducted using iron marble and golf ball to evaluate the walking satisfaction since it can be used by visitors due to the feature of forest road.

• Proceedings of the Korean Geotechical Society Conference
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• 2009.09a
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• pp.1001-1010
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• 2009

The study that unconfined compression strength of intact rock which is the most important factor to determine the bearing capacity effects discontinuities in rock mass has been carried out actively so far. However, the study which is related to lithological characters such as vesicle which is one of the primary characteristics of Basalt has barely been conducted. On this study, We have analyzed the correlation-ship between vesicle and unconfined compression strength and the effect on the bearing capacity, based on the reviewing on the changes of unconfined compression strength as the amount of vesicle of Basalt. It is impossible to analyze the amount of vesicle of Basalt as measuring unit. So it was analyzed by the ratio of the core sample's surface area and another area that vesicle takes up. Also, unconfined compression strength was calculated by point load test and unconfined compression strength test. The analysis shows that vesicle area ratio and unconfined compression strength have the exponential relationship and vesicle area ration is the factor to determine the bearing capacity of Basalt. It is considered that the reliability of calculating of the bearing capacity of Basalt will be improved as we study the correlation-ship between the vesicle area ratio and rock mass grade hereafter.

• Journal of the Korean Geotechnical Society
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• v.22 no.10
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• pp.33-45
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• 2006

C.S.G is a material made by adding cement and water to rock-like material such as riverbed gravel or excavation muck that can be obtained easily near dam si. Recently, the use of C.S.G is gradually increasing as the construction material for dam, road, revement and so on. Commonly, the strength characteristics of C.S.G is affected by various influence factors such as grade, unit cement, age and water contents. In this study, a series of compaction test and unconfined compressive strength test were performed to investigate the relationship between a strength and influence factors such as three kinds of gradation, age, unit cement and water contents with riverbed gravel in Hwa Buk dam. The results show that strength Properties of C.S.G is variously affected by these influence factors. Especially, gradation and water contents are found to be very important factors fur determining the strength of C.S.G material. And, from the results of experimental study, the correlation equations between uncompressive strength and these factors are proposed.

• Journal of the Korean GEO-environmental Society
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• v.14 no.6
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• pp.39-46
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• 2013

The field of ground amelioration, many construction methods have been developed more prosperously up to now, but even now, the majority focuses on the improvement of ground strength. And they could not suggest concrete solutions to the occurrence of environmental issues. To address this problem, soil improvement methods employing organic acid materials have recently been developed as eco-friendly technologies for increasing the soil strength, but details regarding the basic stabilization mechanism are not known yet. Against this background, this research was conducted to examine the soil stabilization mechanism; for this purpose, unconfined compressive strength and pH tests were conducted by using an improved eco-friendly organic acid material. The test results revealed that the samples processed with the organic acid showed a considerable increase in the unconfined compressive strength over time as compared to the strength of the samples that were processed without the organic acid. It was also confirmed that the organic acid material promoted microbial breeding and improved the soil structure by reducing the volume of the voids in the soil. Therefore, the sustainable development of this method needs to be analysed more in the future.

• Geomechanics and Engineering
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• v.6 no.5
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• pp.437-453
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• 2014

This paper studies the swelling and strength characteristics of unimproved and improved expansive soils in terms of the swell potential, swelling pressure, rate of secondary swelling, unconfined compressive strength and California bearing ratio (CBR). The admixtures used in this study are locally available cement and fly ash. The soils used in this study were taken from the Mae Moh power plant, Lampang Province, in northern Thailand. A conventional consolidation test apparatus was used to determine the swelling of the soil specimen. The optimum admixture contents are determined to efficiently reduce the swelling of unimproved soil. The rate of secondary swelling for unimproved soil is within the range of highly plastic montmorillonite clay, whereas the specimens improved with optimum admixture contents can be classified as non-swelling kaolinite. A soil type affects the swelling pressure. Expansive soil improvement with fly ash alone can reduce swelling percentage but cannot enhance the unconfined compressive strength and CBR. The strength and swelling characteristics can be predicted well by the swelling percentage in this study.

• Journal of Ocean Engineering and Technology
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• v.19 no.6 s.67
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• pp.44-49
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• 2005

This paper investigates strength characteristics and stress-strain behaviors of unreinforced and reinforced lightweight soils. Lightweight soil, composed of dredged soil, cement, and air-foam, was reinforced by a waste fishing net, in order to increase its compressive strength. Test specimens were fabricated by various mixing conditions, such as cement content, initial water content, air content, and waste fishing net; then, unconfined compression tests were carried out on these specimens. From the test results, it was shown that reinforced lightweight soil had different behavior after failure, even though it had similar behavior as unreinforced lightweight soil before failure. The test results also showed that stress became constant after peak strength in reinforced lightweight soil, while the stress decreased continuously in unreinforced lightweight soil. It was observed that the strength was increased due to reinforcing effect by the waste fishing net for most cases, except high water content greater than $218\%$. In the case of high water content, a reinforcing effect is negligible, due to slip between waste fishing net and soil particles. In reinforced lightweight soil, secant modulus (E50) was increased, due to the inclusion of waste fishing net.

• Structural Engineering and Mechanics
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• v.36 no.6
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• pp.759-783
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• 2010

In this paper, compressive strength of carbon fiber reinforced polymer (CFRP) confined concrete cylinders is formulated using a hybrid method coupling genetic programming (GP) and simulated annealing (SA), called GP/SA, and a robust variant of GP, namely multi expression programming (MEP). Straightforward GP/SA and MEP-based prediction equations are derived for the compressive strength of CFRP-wrapped concrete cylinders. The models are constructed using two sets of predictor variables. The first set comprises diameter of concrete cylinder, unconfined concrete strength, tensile strength of CFRP laminate, and total thickness of CFRP layer. The most widely used parameters of unconfined concrete strength and ultimate confinement pressure are included in the second set. The models are developed based on the experimental results obtained from the literature. To verify the applicability of the proposed models, they are employed to estimate the compressive strength of parts of test results that were not included in the modeling process. A sensitivity analysis is carried out to determine the contributions of the parameters affecting the compressive strength. For more verification, a parametric study is carried out and the trends of the results are confirmed via some previous studies. The GP/SA and MEP models are able to predict the ultimate compressive strength with an acceptable level of accuracy. The proposed models perform superior than several CFRP confinement models found in the literature. The derived models are particularly valuable for pre-design purposes.

• Magazine of the Korean Society of Agricultural Engineers
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• v.44 no.4
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• pp.123-128
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• 2002

This study was performed to use fiber mixed soil which has clayey soil or sandy soil with fibrillated fiber or monofilament fiber on purpose of construction materials, filling materials, and back filling materials. In addition, this study was conducted to analyze strength properties and fiber reinforcing effect with fiber mixed soil by direct-shear test. In case of fibrillated fiber mixed soil, the more quantity of fiber was in both cohesive soil and sandy soil, the larger shear stress was in respective step of normal load. The respective mixed soil at 0.5% and 0.1% mixing ratio of monofilament fiber mixed soil showed maximum shear stress. According to unconfined compression or direct-shear test, making specimen of the monofilament fiber mixed soil, it is required to be careful and stable mixing method, while it is expected that monofilament fiber mixed soil doesn't increase strength.