• Geomechanics and Engineering
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• 제33권2호
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• pp.133-140
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• 2023

Soil erosion can cause scouring and failures of underwater structures, therefore, various soil improvement techniques are used to increase the soil erosion resistance. The microbially induced calcium carbonate precipitation (MICP) method is proposed to increase the erosion resistance, however, there are only limited experimental and numerical studies on the use of MICP treatment for improvement of surface erosion resistance. Therefore, this study investigates the improvement in surface erosion resistance of sands by MICP through laboratory experiments and numerical modeling. The surface erosion behaviors of coarse sands with various calcium carbonate contents were first investigated via the erosion function apparatus (EFA). The test results showed that MICP treatment increased the overall erosion resistance, and the contribution of the precipitated calcium carbonate to the erosion resistance and critical shear stress was quantified in relation to the calcium carbonate contents. Further, these surface erosion processes occurring in the EFA test were simulated through the coupled computational fluid dynamics (CFD) and discrete element method (DEM) with the cohesion bonding model to reflect the mineral precipitation effect. The simulation results were compared with the experimental results, and the developed CFD-DEM model with the cohesion bonding model well predicted the critical shear stress of MICP-treated sand. This work demonstrates that the MICP treatment is effective in improving soil erosion resistance, and the coupled CFD-DEM with a bonding model is a useful and promising tool to analyze the soil erosion behavior for MICP-treated sand at a particle scale.

• 한국토양비료학회지
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• 제47권3호
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• pp.205-212
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• 2014

Chronological changes of soil organic carbon (SOC) must be prepared by IPCC guidelines for national greenhouse gas inventories. IPCC suggested default reference SOC stocks for mineral soils and relative stock factors for different management activities where country own factors were not prepared. 3.4 million data were downloaded from agricultural soil information system and analyzed to get chronological changes of SOC for some counties and for land use in Korea. SOC content of orchard soil was higher than the other soils but chronological SOC changes of all land use had no tendency in differences with high standard deviation. SOC contents of counties depended on their own management activities and chronological SOC changes of districts also had no tendency in differences. Thus, Korea should survey the official records and relative stock factors on management activities such as land use, tillage and input of organic matter to calculate SOC stocks correctly. Otherwise, Korea should establish a model for predicting SOC by analyzing selected representative fields and by calculating SOC differences from comparing management activities of lands with those of representative fields.

• 한국초지조사료학회지
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• 제22권4호
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• pp.279-286
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• 2002

동일한 토양종류(토양명: 송정통)인 인접한 토양에서 신개간지와 다소 숙전화 된 기경작 초지토양 간의 비옥도 특성과 시비처리별 목초 생산성과 무기양분 함량차이를 비교.검토하고 자 기초시험으로 pot 시험을 수행하였다. 초지 토양의 비옥도 개량에 연관된 퇴비(I보), 석회 (II보) 및 인산(III보)의 시용효과를 단계별로 검토하였다. 본보(II)에서는 3요소 및 고토를 동일하게 기본시비를 한 조건에서 1) 무석회구, 2) 석회 보비구(27g), 3) 석회 다비구(54g, CaCO$_3$/pot)를 처리내용으로 한 두 토양간 석회의 비효를 비교.검토하였다. 1. 시험전 신개간지와 기존초지간 토양의 화학성(비옥도)에 큰 차이를 보였다. 초지토양 비옥도 등급기준(불량-보통-양호)에 기준 한 각 화학성을 신개간지 토양 ↔ 기경작 초지토양간의 차이를 일반적으로 비교하면 불량/보통 ↔ 보통/양호수준을 보였다. 2. 시험 후 토양특성의 변화를 보면 석회시 비로 두 토양 공히, 유효인산 함량은 약간 감소되었고, 유기물 함량은 변화를 보이지 안 했으며 치환성 Ca과 mg 함량이 높아졌다. 인산 흡수계수는 신개간 토양에서 크게 높아졌으나 기경작 초지토양에서는 석회 다비구에서 만 크게 높아졌다. 석회시비에 따른 유효인산 함량 의 저하와 인산흡수계수 상승의 부정적 영향을 퇴비와 병행시비의 경우 개선되었다. 3. 목초의 초기 생육상은 신개간지보다 기경작 초지토양에서 매우 양호하였고, 각 토양 공히 석회 다비구에서 불량해 진 경향을 보였다. 그러나 퇴비와 병행된 석회시비는 석회 단독 시비조건보다 크게 초기생육상이 양호해 졌다. 4. 목초의 수량은 대조구에서 신개간지에 비해 기경작 초지토양에서 50.9%의 더 높은 생산성을 보였다. 석회 보비구에서 각 토양 공히 대조구보다 15-18% 정도 증수하였고 반면에 석회 다비구는 보비구와 비슷하거나 다소 낮야지는 경향을 보였다. 5. 기경작 초지토양의 목초 중 Ca, mg 및 P 함량이 신 개간 토양의 목초 중 함량보다 다소 높았고 석회 보비구에서 Ca, mg 함량이 높아 졌으나 석회 보비구와 다비구간 차이는 경미하였다.

• 한국지하수토양환경학회:학술대회논문집
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• 한국지하수토양환경학회 2001년도 추계학술발표회
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• pp.51-54
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• 2001

This research was carried out to evaluate feasibility of using an Electrokinetic-Fenton(EK-Fenton) technique to treat hydrophobic organic pollutant(phenanthrene) from soils. Experiment examined the effect by introducing a continuous flow of a 3.5% hydrogen peroxide solution at the anode. An electric gradient of 1V/cm was applied to enhance the saturated flow in the soil cell for a period of 11 days. After 11 days or 1 pore volume, overall concentration of residual phenanthrene in the soil cell was 11% and residual phenanathrene concentration in the soil was found to increase with toward the cathode. This results indicated that Fenton-like reaction catalyzed by mineral surface was effective in oxidizing phenanthrene. This results also showed that hydrogen peroxide was effectively transported into the soil by electroosmotic flow as well as by diffusion.

• 한국지하수토양환경학회:학술대회논문집
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• 한국지하수토양환경학회 2006년도 총회 및 춘계학술발표회
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• pp.33-36
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• 2006

The reductive dechlorination of chlorinated organic compounds by soil minerals in soil and groundwater were carried out in this study. FeS, green rust, and magnetite were chosen as the representative soil minerals which were capable of degrading chlorinated compound in soil system. FeS was the most effective reductant in degradation of carbon tetrachloride. The reductive degradation of CT and 1,1,1-TCA by FeS was much faster than that of 1,2-DCB and 2,4-DCP. The reactivity of FeS was effectively improved by the addition of trace metals. The addition of Co to FeS suspension enhanced the reaction rate of 1,2-DCB by a factor of 46 compared to that by FeS without Co.

• 아시안잔디학회지
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• 제9권1호
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• pp.75-80
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• 1995

In eight golf courses of southern area fair way soil profile was investigated for soil physical, chemical properties, and root distribution. These were carried out only A horizon(lScm depth) in one golf course. Soil series was all different, Leaching to lower horizon was greator in order of Mg=$NO_3$> $NH_4$=Ca> K. Organic matter content was higher in B horizon than A in three golf courses. Soil phosphorus appeared to more down greatly in two golf courses. Soil pH was higher in lower horizon of all places. Such pH increase with depth seemed to he related with mineral leaching, Among the horizons of all golf courses BC showed significant correlation with K (EC =0.1025K +0.0157, r=0. 8012 p=0. 001 n=20). Both Fe and Mn were higher in A horizon.

• 한국잠사곤충학회지
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• 제26권2호
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• pp.7-10
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• 1984

뽕나무에 VA mycorrhizae의 1종인 Glomus mosseae, Mosse and frappe를 접종하여 소독을 하지 않은 토양에 심어 6월간 재배한 결과를 요약하면 다음과 같다. 가. VA mycorrhizae 접종 뽕나무는 전체 조장은 15%, 조경은 19%, 뽕잎량은 30%가 더 많았다. 나. VA mycorrhizae접종 뽕나무의 뽕잎 성분은 질소는 12%, 인산은 10%, CaO는 10%가 더 많았고 $K_2$O는 차이가 없었으며 MgO는 20%가 더 많았다. 다. VA mycorrhizae접종 뽕나무 뿌리는 질소는 20%가 더 적었고 인산은 21%가 더 많았다.

• 한국조경학회지
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• 제27권3호
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• pp.109-113
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• 1999

The objective of this research was to develop growth media for artificial ground by blending calcined clay and coconut peat. To achieve this, aggregates of clay particles were mixed with disel oil and heated to high temperature(1150~120$0^{\circ}C$) to expand clays. The particle sizes of expanded clay were controlled to 2~5mm in diameter. Then expanded clayes were mixed with coconut peat and changes of soil physicochemical properties and their effect on plant growth of Hedera L. were determined. The infiltration rate of calcined clay was very high, but the water holding capacity, the cation exchange capacity(CEC), and the nutrient contents were low. The characteritics of coconut peat was vice verse to calcined clay. This indicates that the mixture of calcined clay and coconut peat have the better characteristics than each material. As compared to mineral soil, the infiltration rate, the water holding capacity, the CEC and the nutrient contents increased, but bulk density decreased to about 1/4. And, Hedera L. grown in the mixture of calcined clay and coconut peat(6:4, v/v) had higher plant height, longer leaf length, more total number of leaves per plant and fresh weight than that grown in mineral soil, but statistical differences were not observed between two treatments.

• 한국지하수토양환경학회지:지하수토양환경
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• 제16권6호
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• pp.122-132
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• 2011

Mercury accumulates in biota mainly as methylmercury. In nature, methylmercury shows high affinity to organic matter and $CH_3Hg^+$-organic matter complexation affects the mobility and bioavailabiity of methylmercury. In this study, we examined the methylmercury binding sites in an aquatic humic acid as affected by the pH condition using Hg $L_{III}$-edge extended X-ray absorption fine structure (EXAFS). We evaluated methylmercury binding humic ligands using methylmercury-thiol, methylmerury-carboxyl, and methylmercury-amine complexation models. When $CH_3Hg^+$-to-humic reduced sulfur ratio is 0.3, we found that most of $CH_3Hg^+$ binds to thiol ligands at pH 5 and 7. At pH 7, however, some carboxyl or amine ligand contribution is observed, unlike at pH 5 where $CH_3Hg^+$ almost exclusively binds to thiol ligands. The carboxyl or amine ligand contribution may indicate that some types of thiol ligands in the natural organic matter have relatively low complexation constants or acid dissociation constants compared to those of some carboxyl or amine ligands. Analysis results indicate that ~0.2 fraction of methylmercury binds to amine or carboxyl ligands and ~0.8 to thiol ligands at pH 7.

• 생물환경조절학회지
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• 제3권1호
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• pp.66-71
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• 1994

겨울부터 봄에 걸친 배추의 시설보온재배에서 많이 발생되는 Tipburn현상의 원인을 구명하기 위하여 배추재배 시험구의 토양과 배추의 부위별 무기성분 분석을 했다. 실험결과는 다음과 같다. 1. Tipburn현상의 발생과 토양의 칼슘농도와는 관계가 없었다. 2. 배추부위별 칼슘농도는내엽<중엽<외엽이었고, 내엽맥<중엽맥<뇌엽맥의 순이었다. 3. 이상의 결과로 Tipburn현상의 발생원인은 배추생육의 일정시기에 배추 내엽으로부터 증산작용을 억제시키는 어떤 환경요인에 의해 1차적으로 발생된다고 생각된다.