• 한국약용작물학회지
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• 제23권4호
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• pp.271-276
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• 2015

This study was conducted to investigate the effect of shading degree and rooting media on the growth of Caragana sinica and Sedum middendorffianum after cutting. In C. sinica, the highest rooting rate was obtained in cuttings planted in horticultural soil (Sunshine Mix #1) and peat moss mixture (peat moss : perlite = 1 : 1, v/v) under one layer of 35% shading and in cuttings planted in kanumatsuchi soil mixture (kanumatsuchi soil : decomposition of granite = 1 : 1, v/v) under non-shading. Whereas, regardless of shading degree, most cuttings of S. middendorffianum rooted in both horticultural soil and peat moss mixture. Cuttings of C. sinica showed the highest root length, 10.4cm in kanumatsuchi soil mixture under one layer of 35% shading but the highest fresh and dry weight of roots in kanumatsuchi soil mixture under non-shading. In S. middendorffianum, the highest root length, fresh and dry weight of root were obtained in cuttings planted in horticultural soil under non-shading. With these results, we recommended that cuttings of C. sinica should be propagated in kanumatsuchi soil mixture under non-shading and cuttings of S. middendorffianum in horticultural soil under non-shading.

• Geomechanics and Engineering
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• 제30권5호
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• pp.479-487
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• 2022

This study evaluates the performance of gravel impact compaction piers system (GICPs) in strengthening retrofitting a very loose silty sand layer with a very high liquefaction risk with a thickness of 3.5 meters in a multilayer coastal soil located in Bushehr, Iran. The liquefiable sandy soil layer was located on clay layers with moderate to very stiff relative consistency. Implementation of gravel impact compaction piers is a new generation of aggregate piers. After technical and economic evaluation of the site plan, out of 3 experimental distances of 1.8, 2 and 2.2 meters between compaction piers, the distance of 2.2 meters was selected as a winning option and the northern ring of the site was implemented with 1250 gravel impact compaction piers. Based on the results of the standard penetration test in the matrix soil around the piers showed that the amount of (N₁)₆₀ in compacted soils was in the range of 20-27 and on average 14 times the amount of (1-3) in the initial soil. Also, the relative density of the initial soil was increased from 25% to 63% after soil improvement. Also the safety factor of the improved soil is 1.5-1.7 times the minimum required according to the two risk levels in the design.

• The Korean Journal of Ecology
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• 제19권5호
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• pp.393-402
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• 1996

Density fluctuations of soil microarthropods at the Piagol, Mt. Chiri was assessed on the basis of 113, 096 individuals collected from March 1993 to February 1994. Of 6 classes, and 18 orders, the Arachnida and Insecta were the most numerous members with abundance of 51.4% and 46.3%, respectively. The mean density of the Acari was $13, 310/m^2$ of microarthropods. The Acari were abundant in autumn and less found in winter and the density fluctuation of the Collembola followed a similar trend. The vertical distribution of the mesofauna revealed from the soil samples taken from the surface to 5 and from 5 to 10 cm in depths was as follows. In 5~10 cm layer. Collembola was numerous with abundance of 54.7%, followed by 40.1% fo Acari and the soil microarthropods reached the highest density peak in spring, while the lowest in winter. Populations concentrated in the 0~5 cm layer as much as 62.2% throughtout the season and 82.4% throughtout the altitudes. The Acari / Collembola (A/C) ratio in the 0~5 cm layer was higher than that in the 5~10 cm.

• Geomechanics and Engineering
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• 제34권6호
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• pp.665-681
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• 2023

Liquefaction is one of the most devastating geotechnical phenomena that severely damage vital structures and lifelines. Before constructing structures on problematic ground, it is necessary to improve the site and solve the geotechnical problem. Among ground improvement methods dealing with liquefaction, gravel drain (GD) columns and deep soil mixing (DSM) columns are popular. In this study, the results of a series of seismic experiments in a 1g environment on a structure located over liquefiable ground with different thicknesses reinforced with GD and DSM techniques were presented. The dynamic response of the reinforced ground system was investigated based on the parameters of subsidence rate, excess pore water pressure ratio, and maximum acceleration. The time history of the input acceleration was applied harmonically with an acceleration range of 0.2g and at frequencies of 1, 2, and 3 Hz. The results show that the thickness of the liquefiable layer and the frequency of the input motion have a significant impact on the effectiveness of the improvement method and all responses. Among the two techniques used, DSM in thick liquefied layers was much more efficient than GD in controlling the subsidence and rupture of the soil under the foundation. Maximum settlement values, settlement rate, and foundation rotation in the thicker liquefied layer at the 1-Hz input frequency were higher than at other frequencies. At low thicknesses, the dynamic behavior of the GD was closer to that of the DSM.

• 대한토목학회논문집
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• 제10권1호
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• pp.163-172
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• 1990

비점성토 지반으로부터 세립토가 과다하게 유실되는 것을 방지하기 위한 geotextile 필터의 유효구멍크기를 평가하는 기준은 흙/geotextile 시스템을 통과하는 물의 흐름형태에 따라 크게 달라진다. 일방향흐름을 받는 흙/geotextile 시스템에서는 장기간 물의 흐름에 의해 geotextile과 인접한 지반흙내에 자체적인 흙필터층(soil filter layer) 이 형성될 수 있으므로 geotetile은 보다 큰 흙입자의 유실을 억제시킴으로써 효율적인 필터기능을 수행할 수 있는 반면, 교번흐름을 받는 흙/geotextile 시스템에서는 완전한 흙필터층의 형성이 곤란하므로 보다 작은 흙입자의 유실까지 억제시켜야 한다. 본 연구에서는 이러한 2가지 개념을 토대로 하여 흐름형태별로 이론적인 geotextile의 필터기준을 제안하였으며, 이 필터기준의 타당성을 평가하기 위해 실내 필터특성실험을 수행하였다. 실험결과, 높은 동수경사와 짧은 주기 및 낮은 수직하중 등에서 세립토의 유실이 크게 발생하였기 때문에, 이러한 설계인자들의 영향을 평가하여 수정된 geotextile의 필터기준을 제시하였다.

• 한국산림과학회지
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• 제112권4호
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• pp.490-501
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• 2023

본 연구에서는 강우의 침투과정 및 수분 재분포 현상을 분석하기 위하여 실내 컬럼실험을 수행하였으며, 토층 내 함수비를 효율적으로 측정하기 위하여 딥러닝 기법 중 하나인 합성곱신경망(Convolutional Neural Network, CNN)을 사용하여 함수비 예측 모델을 구축하였다. 컬럼실험으로부터 획득된 디지털 이미지를 구축된 CNN 모델에 적용한 결과 시간에 따른 토층별 함수비를 효과적으로 측정할 수 있었으며, 토층별로 설치된 함수비 센서에 따른 함수비와도 비교적 잘 일치하는 것으로 나타났다. 결과적으로 CNN을 활용하여 토층 내 연속적인 함수비 분포를 파악하는 것이 가능하였으며, 토성 및 지반 함수비 조건에 따른 침투 과정을 효과적으로 분석할 수 있었다.

• Geomechanics and Engineering
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• 제37권4호
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• pp.341-358
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• 2024

This paper reports several plane-strain trapdoor tests conducted to investigate the effects of reinforcement on soil arching development under localized surface loading with a loading plate width three times the trapdoor width. An analogical soil composed of aluminum rods with three different diameters was used as the backfill and Kraft paper with two different stiffness values was used as the reinforcement material. Four reinforcement arrangements were investigated: (1) no reinforcement, (2) one low stiffness reinforcement R1, (3) one high stiffness reinforcement R2, and (4) two low stiffness reinforcements R1 with a backfill layer in between. The stiffness of R2 was approximately twice that of R1; therefore, two R1 had approximately the same total stiffness as one R2. Test results indicate that the use of reinforcement minimized soil arching degradation under localized surface loading. Soil arching with reinforcement degraded more at unloading stages as compared to that at loading stages. The use of stiffer reinforcement had the advantages of more effectively minimizing soil arching degradation. As compared to one high stiffness reinforcement layer, two low stiffness reinforcement layers with a backfill layer of certain thickness in between promoted soil arching under localized surface loading. Due to different states of soil arching development with and without reinforcement, an analytical multi-stage soil arching model available in the literature was selected in this study to calculate the average vertical pressures acting on the trapdoor or on the deflected reinforcement section under both the backfill self-weight and localized surface loading.

• Journal of Ecology and Environment
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• 제30권1호
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• pp.17-21
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• 2007

The organic carbon (OC) distribution of Pinus densiflora forest in Songgye valley at Mt. Worak National Park were studied as a part of the National Long-Term Ecological Research in Korea. In order to investigate the OC distribution, OC in plant biomass, litterfall, litter layer on forest floor, and soil were estimated. The density of P. densiflora forest was 1,300 trees/ha, average DBH was $15.2{\pm}6.17\;cm$ and average tree height was $10.7{\pm}2.56\;m$. The shrub layer was dominated by shrubby Quercus variabilis, Fraxinus sieboldiana and lndigofera kirilowii with low frequency, and herb layer was dominated by Pteridium aquilinum and Miscanthus sinensis. Total amount of OC stored in this pine forest was 142.78 ton C/ha. Organic carbon stored in soil and plant biomass accounted for 59.2% and 37.8%, respectively. Amount of OC distributed in trees, shrubs, herbs and litter layer in this pine forest was 51.79, 2.03, 0.12 and 4.29 ton C/ha, respectively. Amount of OC returned to forest floor via litterfall was $1.50\;ton\;C\;ha^{-1}\;yr^{-1}$. Soil organic carbon (SOC) decreased along the soil depth. Total amount of SOC within 50cm soil depth was $84.55\;ton\;C\;ha^{-1}\;50\;cm-depth^{-1}$.

• 한국환경과학회지
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• 제19권11호
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• pp.1337-1353
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• 2010

This study intended to investigate environmental factors including soil and vegetation in order to understand the environmental and ecological characteristics of 12 different habitats of Iris odaesanensis. These habitats, according to investigations, are mostly located at elevation of 280 m to 1,555 m with angles of inclination ranging from 2 degree to 30 degrees. A total of 273 vascular plants are identified in 23 quadrates of 12 habitats. Dominant species of woody plants in 12 habitats are represented as Quercus mongolica in the tree layer (T1) and the subtree (T2) layer, and Lespedeza maximowiczii, Lindera obtusiloba, Rhododendron schlippenbachii in the shrub (S) layer. The importance value of Iris odaesanensis is 9.65%, as regards the herbaceous layer, and 6 highly ranked species such as Carex siderosticta (3.92%), Meehania urticifolia (2.67%), Spodiopogon cotulifer (2.58%), Aconitum pseudolaeve (2.51%), Carex bostrychostigma (2.28%) and Disporum smilacinum (2.09%) are considered to be an affinity with Iris odaesanensis in their habitats. The degree of their average species diversity is 1.32, and that of dominance and evenness are 0.08 and 0.89, respectively. The type of soil is sandy loam and loam, and the average field capacity of soil is 28.31%. Their average organic matter is 16.71%, soil pH 5.29, and available phosphorus is 9.29%. Correlation coefficients analysis based on environmental factors, vegetation and soil analysis shows that the coverage of Iris odaesanensis is correlated with pH and dominance, and species richness is positive related with species diversity.

• 생물환경조절학회지
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• 제10권4호
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• pp.219-224
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• 2001

포도주 부산물이 혼합처리 시용에 따른 토양중 질소 무기화 및 과정을 구명하기 위해 평창군 비가림재배 시설하우스에 수행하였다. 질소무기화 및 질산화는 심토층보다 표토층에서 높게 나타났다. 생육전반에 걸쳐 총 질소 무기화 및 질산화 량은 처리간에 다양하였지만, 전반적으로 총 질소 무기화는 정식 후 90일 까지 증가하였지만 그 이후로는 감소하였다. 표토층에 있어 최고 질소 무기화 및 질산화는 정식후 90일에 T4구에서 관측되었다. 가장 높은 질소 무기화는 정식 후 30일에 무처리구에서 272.5mg.kg$^{-1}$과 정식 후 90일에 T4구에서 843.4 mg.kg$^{-1}$으로 나타났다. 또한 질산화량은 T4구에서 정식 후 90일에 872.2mg.kg$^{-1}$으로 가장 높게 나타났다.