• Structural Monitoring and Maintenance
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• 제11권3호
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• pp.187-202
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• 2024

For the problems of high compressibility and low strength of peat soil formed by lake-phase deposition in Dianchi Lake, microbial-induced calcium carbonate deposition (MICP), phyto-urease-induced calcium carbonate deposition (EICP) and phyto-urease-induced calcium carbonate deposition combined with lignin (EICP combined with lignin) were used to reinforce the peat soil, the changes in mechanical properties of the soil before and after the reinforcement of the peat soil were experimentally investigated, and the effect and mechanism of peat soil reinforcing by the three reinforcing techniques were tested and analyzed using X-ray diffraction (XRD) and scanning electron microscope (SEM). The results show that: compared to the unreinforced remolded peat soil specimens, the unconfined compressive strength (UCS), cohesion and internal friction angle of the specimens reinforced by MICP, EICP and EICP combined with lignin techniques have been greatly improved, and the permeability resistance has been improved by two, two and three orders of magnitude, respectively; the different methods of reinforcing generate different calcium carbonate crystalline phases, with the EICP combined with lignin technique generating the most stable calcite, and the MICP and EICP techniques generating a mixed phase of calcite and spherulitic chalcocite. Analyses showed that for peat soil reinforcement, the acidic environment of peat soil inhibited the growth and reproduction of bacteria, EICP technology was superior to MICP technology, and the addition of lignin solved the defect of the EICP technology that did not have a "nucleation site", so EICP combined with lignin reinforcement was preferred for the improvement of peat soil.

• 한국환경농학회지
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• 제41권2호
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• pp.101-107
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• 2022

BACKGROUND: Soil amendment was necessary applied for the sand that had been used to root zone of green ground in golf course because of its low water retention power and cation exchangeable capacity. This study was conducted to evaluate the effect of the mixed ratio of peat moss and coconut coir as soil amendment materials on the soil physicochemical properties applied to rootzone based on sand. METHODS AND RESULTS: The soil amendments were blended at 0, 3, 5, 7 and 10% by soil volume. The pH in the peat moss treatment was lower than that of control (0% soil amendment), and pH and electrical conductivity (EC) in the coconut coir were higher. The blending ratio of peat moss was negatively correlated with pH of rootzone soil (p<0.01), and that of coconut coir positively with EC (p<0.01). As compared with control, capillary porosity, the physical factors such as air-filled porosity, total porosity, and hydraulic conductivity of rootzone soil were increased by applying peat moss and coconut coir. For correlation coefficients between percentage of soil amendments and soil physical factors, peat moss and coconut coir were positively correlated with porosity and hydraulic conductivity (p<0.01). CONCLUSION(S): These results indicated that the application of peat moss and coconut coir affected on the change of physicochemical properties of rootzone soil, and improved soil porosity and hydraulic conductivity.

• Geomechanics and Engineering
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• 제29권1호
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• pp.13-23
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• 2022

Peat soil has the characteristics of high moisture content, large void ratio and low shear strength. In this study, unconfined compressive strength and SEM tests are conducted to investigate the effects of ultrahigh moisture content, cement content, organic content and pH value on the strength of solidified peat. As an increase in the cement content and curing period, the failure mode of solidified peat soil changes from ductile failure to brittle failure. The influence of moisture content on the strength of solidified peat is greater than the cement content. As cement content increases from 10% to 30%, strength of solidified peat at a curing age of 28 days increases by 161%~485%. By increasing water content by 100%, decreases of solidified peat at a curing age of 28 days is 42%~79%. Compared with the strength of solidified peat with a pH value of 5.5, the strength of peat with a pH value of 3.5 reduces by 10% ~ 46%, while the strength of peat with a pH value of 7.0 increases by 8% ~ 38%. It is recommended to use filler materials for stabilizing peat soil with moisture content greater than 200%. Because of small size of clay particles, clay added in the cement solidified peat can improve much higher strength that that of sand.

• 현장농수산연구지
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• 제22권2호
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• pp.17-22
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• 2020

This study was conducted to find out the optimum composition of nursery soil for raising seedling of Zelkova serrata. The treatments were regulated with the three different soil types : full peat moss(PM 100%), peat moss + perlite + vermiculite(1:1:1), peat moss + perlite + vermiculite(1:2:1). The full peat moss(PM 100%) showed the highest photosynthetic activity such as maximum photosynthesis rate(PN max), water use efficiency(WUE), Fv/Fm, PIabs and SPAD value. And also, full peat moss(PM 100%) showed relatively better growth performances. As a result of surveying the whole experiment, full peat moss(PM 100%) soil increases growth performances and enhances overall quality.

• 한국환경보건학회지
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• 제33권5호
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• pp.462-469
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• 2007

Isolation and application of oil-degradation microbes from the oil-contaminated soil and the determination of optimal operation conditions about the peat moss, the addition for the oil-biodegradation. After all experiments, we have acquired three important conclusions: First, we found out the 4 microbes, Pseudomonas fluorescens, Pseudomonas aeruinosa, Kurtia sp., Bacillus ceres, with excellent capability for the oil-degradation; Second, the optimal operating conditions of the peat moss for TPH treatment were pH $7{\sim}8$, temperature $25{\sim}30^{\circ}C$, water content 20%, mixing 2 times/ day, addition volume 2%; Third, in case of the application to the oil-contaminated soil with 4 mixed microbes, the removal efficiency of TPH was increased from 54% to 83% in oil-contaminated soil and from 65% to 85% in oil-contaminated soil with the peat moss.

• 한국토양비료학회지
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• 제43권6호
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• pp.858-863
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• 2010

블루베리는 유기물 함량이 높고 물리성이 양호한 산성토양에서 안정적인 생육을 기대할 수 있다. 그러나 국내 작물 재배토양은 배수가 불량하고 유기물 함량이 낮은 알칼리 토양이 대부분이다. 따라서 블루베리 재배 농가들은 적합한 토양으로 개량하기 위하여 피트모스에 크게 의존하고 있으나, 작물생육과 경제성이 고려된 혼합비율의 정보가 미흡한 실정이다. 본 연구는 경제성과 안정생육을 고려한 적정 피트모스 혼합비율 구명과 이와 비슷한 물리 화학적 특성을 가진 톱밥과 코코피트의 적용 가능성을 검토하고자 본 연구를 수행하였다. 본 연구에 사용된 유기자재는 피트모스, 코코피트 그리고 신선한 톱밥이며, 각각의 유기자재는 토양에 부피비율로 0%, 12.5%, 50% 그리고 100%로 혼합하여 처리하였다. 시험 후 유기자재별 혼합비율에 따른 토양 pH는 피트모스와 톱밥이 각각 100%인 처리구가 3.67과 3.73으로 가장 낮았으며, 피트모스 50% 혼합구가 5.30으로 뒤를 이었다. 유기물 함량은 모든 자재가 혼합비율과 같은 경향을 나타냈으며, 이와 같은 경향은 코코피트 혼합구의 치환성 칼리 함량에서도 동일하였다. 그러나 유효인산과 치환성 칼슘과 마그네슘 함량은 혼합비율이 증가할수록 감소하는 경향이었다. 처리별 엽중 질소함량은 피트모스와 코코피트 처리에서 혼합비율이 증가할수록 감소하는 경향을 나타냈으며, 톱밥 처리는 혼합비율에 따른 경향이 나타나지 않았다. 인산 함량은 톱밥과 코코피트 처리에서 혼합비율이 증가할수록 감소하는 경향을 나타냈으나, 칼리 함량은 증가하는 경향이었고, 칼슘과 마그네슘 함량은 유기자재간 혼합비율간 차이가 없었다. 유기자재별 혼합비율에 따른 블루베리의 초장, 경경, 건물중 등의 생육은 피트모스 50%> 피트모스 12.5%> 코코피트 12.5% 순 이었으며, 피트모스 100% 처리구의 생육은 매우 저조하였다. 따라서 블루베리의 토양환경 개선과 우량한 생육을 위한 토양 개선자재로서는 피트모스가 가장 효과적이었음을 확인하였으며, 경제성을 고려한 혼합 비율은 25-50% 범위가 타당하다 보겠다.

• Geomechanics and Engineering
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• 제20권1호
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• pp.75-86
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• 2020

This study aims to simulate the stabilization process of fibrous peat samples using end-bearing Cement Deep Mixing (CDM) columns by three area improvement ratios of 13.1% (TS-2), 19.6% (TS-3) and 26.2% (TS-3). It also focuses on the determination of approximate stress distribution between CDM columns and untreated fibrous peat soil. First, fibrous peat samples were mechanically stabilized using CDM columns of different area improvement ratio. Further, the ultimate bearing capacity of a rectangular foundation rested on the stabilized peat was calculated in stress-controlled condition. Then, this process was simulated via a FEM-based model using Plaxis 3-D foundation and the numerical modelling results were compared with experimental findings. In the numerical modelling stage, the behaviour of fibrous peat was simulated based on hardening soil (HS) model and Mohr-Coulomb (MC) model, while embedded pile element was utilized for CDM columns. The results indicated that in case of untreated peat HS model could predict the behaviour of fibrous peat better than MC model. The comparison between experimental and numerical investigations showed that the stress distribution between soil (S) and CDM columns (C) were 81%C-19%S (TS-2), 83%C-17%S (TS-3) and 89%C-11%S (TS-4), respectively. This implies that when the area improvement ratio is increased, the share of the CDM columns from final load was increased. Finally, the calculated bearing capacity factors were compared with results on the account of empirical design methods.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2004년도 춘계학술발표회
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• pp.235-242
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• 2004

For this study, a Peliyagoda area located on a route was selected among many sections of a CKE(Colombo to Katunayake Expressway) route in Sri-Lanka. Its subground consists of a very weak and thick peat soil named amorphous or fibrous peat. All of data, obtained in the design process of soft ground treatment were analyzed to evaluate the settlement characteristics resulted from an embankment load and to present reasonable methods for estimation of secondary compression settlement. For these purposes, soil parameters were used obtainedby field and laboratory tests the settlement analyses were conducted base on the field monitoring results within 20 months. In addition, Reasonable methods were studied to estimate primary consolidation and secondary compression settlement.

• 한국습지학회지
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• 제22권4호
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• pp.328-336
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• 2020

본 연구에서는 국내 피트층의 토양특성(입지환경)을 분석하여 충남 태안군의 신규 피트 분포지역을 예측하고 피트층의 특성을 비교하였다. 국내에서는 충남 태안, 경기 평택, 강원 강릉, 울산, 전북 익산 및 전남 장흥 등에서 피트층에 대한 연구가 진행되었으며, 이 연구 지역들의 피트층 토양에 대한 분포지형, 퇴적양식, 배수등급 및 토양아목의 특성을 통해 입지환경을 분석하고 피트 분포 예측기준을 선정하였다. 충남 태안군의 사례연구를 통해 피트층 분포 지역은 두 가지 형태로 확인되었다. 첫 번째로는 곡간지, 충적붕적층, 배수 약간불량 및 aqualfs 특성을 보이는 지역과, 두 번째로는 해성평탄지, 충적층, 배수 매우불량 및 aquepts 지역들이었다. 실제 피트층의 분포 확인을 위해 현장 탐침조사를 수행하였으며, 신규 피트층과 기존 연구 결과를 비교한 결과 국내의 피트 발견지역은 모두 해안선에서 10 km 이내에 위치하며, pH 5, 휴믹산 15% 이내의 성분으로 구성된 dark brown 계열 색상의 피트로 확인되었다. 또한 신규 피트층은 타지역에 비해 깊이는 깊고 두께는 두꺼우나 분해도는 상대적으로 낮은 것으로 나타났다.

• 한국지하수토양환경학회:학술대회논문집
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• 한국지하수토양환경학회 2004년도 총회 및 춘계학술발표회
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• pp.135-138
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• 2004

본 연구는 중금속으로 오염된 폐수처리에 있어 친환경적 유기흡착제로서 휴믹물질의 활용성을 평가하기 위한 기초 연구로서 이탄(peat moss)으로부터 Humin을 분리 한 후, 중금속 이온(Cd(II),Cu(II))과의 흡착특성을 조사하였다. 이탄으로부터 추출한 peat-Humin의 함량은 94%이상을 나타냈으며, 분자의 작용기 특성은 일반 토양 휴믹물질(soil humic substance)과 유사하였다. peat-Humin과 중금속 이온(Cd(II),Cu(II))과의 흡착 반응은 5분내에 빠른 흡착형을 보였으며, pH 5-6에서 가장 높은 중금속 제거율을 보였다. pH 3의 산성조건에서도 50%정도의 제거율을 보였다. pH 5에서의 등온흡착 실험결과를 Freundlich 등온식에 적용하여 해석한 결과, 각의 중금속에 대한 peat-Humin의 흡착상수(Kf)는 Cd(II)이 8.07 그리고 Cu(II)가 4.56으로 나타났다.