• Journal of the Korean Geotechnical Society
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• v.40 no.3
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• pp.55-63
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• 2024

Xanthan gum biopolymer is an ecofriendly ground stabilizer that maintains stability in a wide range of temperatures and pH values. The binding effect of sandy soil particles realized by injecting xanthan gum biopolymer is dependent on the xanthan gum matrix, which is formed during the drying process; thus a study on the effects of the drying process of the xanthan gum solution on the changes in stiffness characteristics of sandy soil is required. In this study, shear wave velocity and electrical resistivity were monitored in sandy soil specimens saturated with biopolymer solutions of different gravimetric concentrations to investigate the improvement effects of biopolymer-treated sandy soils with the drying process. The experimental results reveal that both shear wave velocity and electrical resistivity increase during drying process. The results demonstrate the stiffness improvement effects of biopolymer-treated sandy soils. In addition, a higher stiffness improvement effect was monitored in the biopolymer-treated sandy soils with a higher gravimetric concentration. The results of this study may be used to estimate the stiffness improvement effects of sandy soils treated with biopolymer solutions with the drying process.

• Journal of the Korean Geotechnical Society
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• v.19 no.5
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• pp.243-252
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• 2003

Environmental Double Pile method was presented as a device to improve low permeable contaminated soil. EDP is one of the latest technology in a concept of one step process that is applied to low permeable contaminated ground to reutilize the site by enhancing drainage, contaminated remediation, bearing capacity of piles. In order to evaluate on-site applicability of this technology, qualities of EDP's drainage, strength and remediation were assessed through a series of experiments; EDP was verified to achieve remediation and improvement of soft ground.

• Korean Journal of Optics and Photonics
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• v.12 no.1
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• pp.10-16
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• 2001

A new digital serrodyne (DS) signal processor for the close-loop fiber optic gyroscope was designed and implemented. It is based on a new algorithm that can solve the remaining problems of the existing digital serrodyne processing by utilizing a new modulation wavefonn. The algorithm was implemented in an FPGA and tested. Theoretical limit and experimental value of the random walk were measured to be 2.6 and 3.3 deg/hr/$\sqrt{Hz}$, respectively. And drift of the processor is smaller than that by Shupe's effect.effect.

• Proceedings of the Korea Institute of Fire Science and Engineering Conference
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• 2011.11a
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• pp.537-540
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• 2011

중요 목조문화재를 산불이나 인접 건축물의 화재로부터 보호하기 위한 방안으로 수막노즐을 제시하였다. 바닥으로부터 일정압력 이상으로 상승하는 물줄기로 수막을 형성하여 복사열을 차단함으로써 $200^{\circ}C{\sim}250^{\circ}C$에서 발생하는 목재의 열분해를 막기 위한 것으로 기존에 설치되어 있는 강원도 낙산사와 전라남도 무위사의 수막노즐의 설치상태를 확인해 보았고 이를 보완 개량하기 위한 방안으로 평상시 덮개에 덮인 노즐을 설치하여 경관을 손상시키지 않게 하였고 사용 시 수직상승하여 물을 분사할 수 있는 상하승강식 노즐봉과 이를 효과적으로 설치하는 방법에 대하여 연구되었다.

• Journal of Environmental Impact Assessment
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• v.32 no.3
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• pp.157-165
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• 2023

In Korea, a major contaminant of farmland soils in the vicinity of abandoned mines is arsenic, for which the general soil reclamation method is contaminated soil stabilization and cover the stabilized soil with clean soil at a thickness of 40 cm. In a previous pot experiment study we confirmed the feasibility of a lower thickness (20 cm) of covering soil for such reclamation in abandoned coal mines, where arsenic contamination levels are generally lower than in metal mines. In this subsequent study a field experiment including rice plant cultivation in field test plots was conducted. For over 4 months, the transfer of arsenic from the contaminated soil to the unpolished rice grains was reduced by 44% when a clean soil covering with a thickness of 20 cm was applied. The maximum decrease (56%) was shown when the stabilization process was performed before the covering. These results reveal a lower thickness of clean soil covering has a high feasibility and it can increase cost-efficiency in the reclamation of an abandoned coal mine.

• Journal of the Korean Geosynthetics Society
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• v.14 no.2
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• pp.1-9
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• 2015

In this study, the objective of the study is to evaluate the effect of calcium carbonate powder, produced by the microbial reactions, on the strength of soft ground (sand). To analyze the cementation effects of calcium carbonate powder produced by microbial reactions on the strength of the sand, six different types of specimens (untreated, calcium carbonate, cement, carbonate+cement (1:9, 3:7, 5:5)) were made. The specimen were tested after curing (7 and 28 days). Uniaxial compressive strengths were measured on $D5cm{\times}H10cm$ specimens. Based on the test results, as both the weight ratio and the curing period increase, calcium carbonate, cement, and calcium carbonate+cement specimens showed an increase in the strength. In addition, compared with the strength of the specimen with cement, the strengths of the specimens with mixing ratios of 1:9, 3:7, and 5:5 (carbonate : cement) were found to be 93.5~95.8%, 825.%, 65.2~70.6%.

• Applied Biological Chemistry
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• v.6
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• pp.45-50
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• 1965

To confirm the increase effect of $MNH_4$ which has been compounded as a result of two years' potted rice experiments, we have established simple experiment areas in the paddy field of Kyung-Puk, Kyung-Nam and Chon-Puk Provinces and have done the completely randomized design experiments with the following results. 1. Comparison of the gross weight of the harvested rice (Straw included) : The $MNH_4$ 1-area has produced 10-28% more harvest than that of control-area. 2. Comparison of the weight of the Unpolished Rice: The $MNH_4$ 1-area has shown 10-23% increase compared with the control-area. 3. In the comparison of the nutrients of the rice from the $MNH_4-area$ with those of the rice from the control area, $MNH_4-area$ showed increase of $N_2$, $P_{2}O_5$ and $SiO_2$ but a slight decrease of $K_2O$.

• Proceedings of the Korean Society of Organic Agriculture Conference
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• 2009.12a
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• pp.306-306
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• 2009

본 실험은 백세주 주정박이 벼의 생육과 토양 비옥도 개선에 미치는 영향을 조사하였다. 백세주 주정박은 압착된 주박을 재 발효시켜 단식증류기로 증류하여 알코올을 회수 후 발생된다. 실험 처리구는 무시용, 요소, 주정박 처리구로 하였고, 벼 질소비료 표준시비량 11kg N/10a를 기준으로 하여 전량 기비로 사용하였다. 백세주 주정박의 유효성분과 유해성분을 분석하였고, 토양에 주정박을 시용 전 후의 이화학적 분석을 하였다. 벼 실험 품종은 오대벼(Oryza sativa L.)이고, 벼의 생육과 수량 및 미질을 분석하였다. 백세주 주정박의 pH는 3.60, 유기물함량 90.12%, 염농도 0.72ds/cm, 수분함량 88%, 질소 0.21%, 인산 0.24%, 칼리 0.09%로 나타났다. 유해성분(중금속)분석결과 비소 0.03ppm, 크롬 0.09ppm, 구리0.91ppm, 납 0.05ppm, 니켈 0.05ppm, 아연 1.30ppm, 망간 3.28ppm, 철 34.86ppm로 나타났다. 토양이화학적 분석결과 주정박 시용처리구의 유기물함량과 질소 및 인산은 각각 23.0g/kg. 0.11%, 89mg/kg로 무시용과 요소처리구에 비해 유의한 차이를 보였다. 벼 이식 후 140일째 생육분석결과 초장 82.60cm, 옆폭 1.40cm, 옆장 37.70cm, 지상부건물중 59.21g로 다른 2개 처리구에 비해 유의한 차이를 보였다. 벼의 수량은 주정박 시용 처리구가 449.0kg/10a로 무시용 89.66kg/10a와 요소 401.66kg/10a에 비해 유의적인 차이를 보였다. 백세주 주정박 시용을 통해 토양 개량 효과를 기대할 수 있고, 공시 토양의 토양 개량 효과가 벼의 생육에 긍정적인 영향을 끼치는 것으로 나타남에 따라 백세주 주정박의 토양개량제로서의 활용 가능성을 확인하였다.

• Journal of the Korean Geotechnical Society
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• v.34 no.12
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• pp.105-113
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• 2018

In this study, the engineering properties including bearing capacity of subgrades stabilized with a binder are analyzed by laboratory and field experiments. The main components of the binder are CaO and $SO_3$. After the binder was mixed with a low plasticity clay, the passing rates were relatively decreased as the sieve mesh size increased. Not only did the soil type change to silty sand, but engineering properties, such as the plasticity index and modified California bearing ratio (CBR), were improved for the subgrade. A comparison of the compaction curves of the stabilized subgrade and field soil compacted with the same energy demonstrated an increase of approximately 6% in the maximum dry unit weight, slight decrease in optimum moisture content, and considerable increase improvement in grain size. In the modified CBR test, the effect of unit weight and strength increase of the modified soil (with a specific amount of binder) was remarkably improved. As the proportion of granulated material increased after the addition of binder, the swelling was reduced by 3.3 times or more during initial compaction and 6.5 times by final compaction. The unconfined compressive strength of the specimens was maintained at the homogeneous value with a constant design strength. The stabilized subgrade was validated by applying it in the field under the same conditions; this test demonstrated that the bearing capacity coefficients at all six sites after one day of compaction exceeded the target value and exhibited good variability.

• Journal of the Korean Geotechnical Society
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• v.25 no.8
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• pp.33-45
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• 2009

The conventional single-core PBDs have been widely used in order to accelerate consolidation settlement of soft grounds. When using the single-core PBD in a thick clay deposit, a delay of consolidation may occur due to high confining pressure in the thick deposit and necking of drains. This study is to compare the performances of soil improvement by the single-core and double-core PBD installed at a site in Busan New Port which exhibits approximately a 40m-thick clay layer. An in-situ test program was performed at the test site where a set of the double-core PBDs and single-core PBDs were installed to compare the efficiency of each drain. In addition, the discharge capacity of each PBD has been measured using the modified Delft Test. A series of laboratory tests for estimating in-situ soil properties have also been performed in order to obtain input parameters for a numerical program ILLICON. The discharge capacity of the double-core PBD is higher than that of the single-core PBD in the modified Delft Test. However it is observed from the comparative in-situ test and numerical analysis that there is no difference in the performance of ground improvement between the two drain systems. This discrepancy comes from the fact that the amount of water released during consolidation in most common field conditions is much smaller than the capacity of even the single core PBD. And thus, considering actual field conditions, it can be concluded that the single-core PBD has enough discharge capacity even in the thick clay deposit such as this test site.