• Title/Summary/Keyword: soft foundation

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Characteristics of Bearing Capacity for SCP Composite Ground reinforced by the Sheet piles Restraining Deformation (변위억제형 Sheet pile 설치에 따른 SCP복합지반의 지지력 특성)

  • Park, Byung-Soo
    • Journal of Navigation and Port Research
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    • v.30 no.8 s.114
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    • pp.711-719
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    • 2006
  • A series of geotechnical centrifuge model tests and numerical modelling have been performed to study engineering characteristics of the composite ground reinforced by both the Sand Compaction Piles(SCPs) and the deformation-reducing sheet piles. The research has covered several key issues such as the load-settlement relation, the stress concentration ratio and the final water content of the ground Totally three centrifuge tests have been conducted by changing configuration of the sheet piles, i.e., a test without the sheet pile, a test with the sheet pile at a single side and a test with the sheet piles at the both sides. In the model tests, a vertical load was applied in-flight on the ground surface. On the other hand, class-C type numerical modelling has been performed by using the SAGE-CRISP to compare the centrifuge test results using an elasto-plastic model for SCPs and the Modified Cam Clay model for the soft clay. It has been found that the sheet piles can restraint failure of foundation, thereby increasing yield stress of the ground. The stress concentration ratio was in the range of $2{\sim}4$. In addition, numerical analysis results showed reductions both in the ground heave($20{\sim}30%$) and in the horizontal movement($28{\sim}43%$), demonstrating the deformation-reducing effect of the sheet piles.

2-D Axisymmetric Non-linear Finite Strain Consolidation Model Considering Self-weight Consolidation of Dredged Soil (준설매립지반의 자중압밀을 고려한 2차원 축대칭 비선형 유한변형 압밀 모델)

  • Kwak, Tae-Hoon;Lee, Dong-Seop;Lim, Jee-Hee;Stark, T.D.;Choi, Eun-Seok;Choi, Hang-Seok
    • Journal of the Korean Geotechnical Society
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    • v.28 no.8
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    • pp.5-19
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    • 2012
  • Vertical drains along with the preloading technique have been commonly used to enhance the consolidation rate of dredged placement formation. In practice, vertical drains are usually installed in the process of self-weight consolidation of a dredged soil deposit because this process takes considerable time to be completed, which makes conventional analytical or numerical models difficult to quantify the consolidation behavior. In this paper, we propose a governing partial differential equation and develop a numerical model for 2-D axisymmetric non-linear finite strain consolidation considering self-weight consolidation to predict the behavior of a vertical drain in the dredged placement foundation which is installed during the self-weight consolidation. In order to verify the developed model in this paper, results of the numerical analysis are compared with that of the lab-scaled self-weight consolidation test. In addition, the model verification has been carried out by comparing with the simplified method. The comparisons show that the developed model can properly simulate the consolidation of the dredged placement formation with the vertical drains installed during the self-weight consolidation. Finally, the effect of construction schedule of vertical drains and of pre-loading during the self-weight consolidation is examined by simulating an imaginary dredged material placement site with a thickness of 10 m and 20 m, respectively. This simulation infers the applicability of the proposed method in this research for designing a soil improvement in a soft dredged deposit when vertical drains and pre-loading are implemented before the self-weight consolidation ceases.

The Operative Treatment using Mini-open Sinus Tarsi Approach for Displaced Intraarticular Calcaneal Fractures (전위성 관절내 종골 골절에서 최소 침습적 족근동 도달법 및 압박나사 내고정술을 이용한 수술적 치료)

  • Kim, Yong-Min;Cho, Byung-Ki;Shon, Hyun-Chul;Park, Ji-Kang;Jeong, Ho-Seung
    • Journal of Korean Foot and Ankle Society
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    • v.16 no.4
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    • pp.247-256
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    • 2012
  • Purpose: This study was performed to evaluate the clinical outcomes of operative treatment using mini-open sinus tarsi approach for displaced intraarticular calcaneal fractures. Materials and Methods: We studied 18 cases (16 patients) of intraarticular calcaneal fractures who were treated with sinus tarsi approach by same surgeon. The mean age of patients was 44.8 years, and mean follow-up period was 17.2 months. The measurement of B$\ddot{o}$hler angle, Gissane angle, the degree of articular surface depression, and the period to union were performed through preoperative and postoperative radiographs. The clinical evaluation was performed according to hindfoot score of the American Orthopaedic Foot and Ankle Society (AOFAS) and scale of the Creighton-Nebraska health foundation (CNHF). Results: B$\ddot{o}$hler angle and Gissane angle had improved significantly from preoperative average $9.8^{\circ}$, $117.6^{\circ}$to average $22.4^{\circ}$, $113.4^{\circ}$ immediate postoperatively, and had maintained to average $21.8^{\circ}$and $114.2^{\circ}$ at the last follow-up. The degree of articular surface depression had improved significantly from preoperative average 5.2 mm to 1.2 mm at the last follow-up. All cases achieved bone union, and the period to union was average 10.5 weeks. AOFAS score was average 86.2 points at the last follow-up. There were 7 excellent, 9 good, and 2 fair results according to the CNHF scale. Therefore, 16 cases (88.8%) achieved satisfactory results. Conclusion: The minimally invasive sinus tarsi approach using headless compression screw seems to be an effective surgical method for displaced intraarticular calcaneal fractures, because of the possibility of accurate restoration of articular surface and the low risk of postoperative soft tissue complications.

Behavior of Bearing Capacity for Shallow Foundation on a Sand overlying Clay Depending on Bearing Capacity Ratio (점토층 위 모래지반의 지지력비에 따른 얕은 기초의 지지력 거동)

  • Jung, Min Hyung;Shin, Hyo Hee;Lee, Song
    • Journal of the Korea institute for structural maintenance and inspection
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    • v.15 no.1
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    • pp.198-208
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    • 2011
  • When a structure which has relatively low load constructs on soft clay, the bearing capacity of the ground will be improved by sand overlying clay. In this condition, verifying the bearing capacity is difficult from the P.B.T etcetera in the in-situ. So, it is needed to estimate precise bearing capacity in the design process. In this study, 2-dimensional chamber tests and FEM analyses are conducted to evaluate behavior of bearing capacity for shallow foundations on a sand overlying clay. Because depth ratio H/B and bearing capacity ratio $q_c/q_s$ are selected as main factors, height of a sand, undrained shear strength of a clay and width of a loading are designated as variables. Results from chamber tests are very similar with those of FEM analyses. And it shows that punching shear mechanism is more suitable than the equation of Okamura et al.(1998). To make continual application of load spread mechanism, the equivalent load spread angle is proposed for H/B and $q_c/q_s$. Also, the linear regression equation of critical depth ratio Hf is suggested for $q_c/q_s$.

Modelling and Analysis of Roll-Type Steel Mats for Rapid Stabilization of Permafrost (I) - Modeling - (영구동토 급속안정화를 위한 롤타입강재매트의 모델링과 해석(I) - 해석모델의 수립 -)

  • Moon, Do Young;Kang, Jae Mo;Lee, Janggeun;Lee, Sang Yoon;Zi, Goangseuo
    • Journal of the Korean Geosynthetics Society
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    • v.13 no.4
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    • pp.97-107
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    • 2014
  • Finite element modelling and analysis were conducted for the roll-type steel mats which were placed on loose sand and subjected to a standard truck wheel load in this study. The roll-type steel mats mean that the steel mats can be folded as a circle shape for the carrying to fields in cold regions where workability is limited and are developed for a rapid rehabilitation method for roadway across soft ground which is caused by thawing during the summer season in cold regions. The model is composed of link elements to simulate nonlinear behavior of connections between steel mats, thick shell elements to have flexural stiffness of the steel mats, and springs to simulate characteristics of foundation soils. The structural behaviors of the shell, link elements, and springs were verified at each modelling step through experiment and analysis. Beam and shell analysis without the link elements were conducted and compared to results obtained from the model presented in this study. Significant vertical displacement is shown in the shell model with hinge connections. Therefore, the results demonstrate that the analysis model for the roll-type steel mats on loose sand needs further detail parametric studies.

Fundamental Cultural Characteristics of Chlorociboria spp. Native to Korea (한국에 자생하는 녹청균류의 기초 배양 특성)

  • Jeon, Sung-Min;Ka, Kang-Hyeon;Wang, Eun-Jin;Ryoo, Rhim;Jang, Yeongseon
    • The Korean Journal of Mycology
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    • v.46 no.2
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    • pp.145-160
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    • 2018
  • Members of Chlorociboria are soft-rot ascomycetes that produce blue-green pigment. We investigated the growth characteristics of two Korean species of Chlorociboria, eight strains of Chlorociboria aeruginascens and Chlorociboria poutoensis, under various culture conditions (solid media, temperature, pH) and screened them for extracellular enzyme activity. Although the growth rate was slow, all tested strains of Chlorociboria spp. grew well on potato dextrose agar (PDA; 16.3~42.6 mm after 60 days) or Sabouraud dextrose agar (SDA), but not on malt extract agar (MEA). Compared with C. aeruginascens strains, C. poutoensis strains exhibited higher expression of blue-green pigments on both PDA and SDA media. The optimal temperature for mycelial growth was $20{\sim}25^{\circ}C$, and mycelial growth was lower at $30^{\circ}C$ than at $10^{\circ}C$. All strains tended to have increased mycelial growth as the incubation temperature increased in the range of 10 to $20^{\circ}C$. The optimal pH of potato dextrose broth (PDB) for mycelial growth varied according to the strain under static culture conditions. Maximum biomass production was obtained at pH 6.0 for NIFoS 579 ($114.3{\pm}5.1mg/60days$), but it maintained a stable pigment expression under a broad pH spectrum. The activities of both cellulase and laccase were observed in all tested strains of Chlorociboria spp. Enzyme activities of NIFoS 579 were remarkably higher than those of the other strains. From these results, we suggest that C. poutoensis NIFoS 579 is a potential candidate for use as a source of natural blue-green dye.

The types of name spectrum and their characteristics of domestic fashion brand names - focusing on women' wear and bisex wear - (국내(國內) 의류(衣類)브랜드 네임의 네임 스펙트럼 유형(類型)및 특성(特性) - 여성복(女性服)과 남(男).여(女) 공용복(共用服)을 중심(中心)으로 -)

  • Kwon, Hae-Sook;Oh, Yeun-Jung
    • Journal of Fashion Business
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    • v.9 no.5
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    • pp.65-76
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    • 2005
  • The purpose of this research is to investigate the types of name spectrum and their characteristics of domestic fashion brand names focusing on women' wear and bisex wear, and also studied the differences based on the sex of brand target. 224 of women's wear brands and 99 of bisex wear brands were selected from ‘2002 Korea Fashion Yearbook’ under the criterion that their brand names were made in Korea and they should engage in business in 2002. The data analysis quatitatively evaluate the frequency and qualitatively evalute the image of brand product and the meaning of brand name. The result as follows; 1.The domestic fashion brands for women's and bisex wear appeared to have to three types of name spectrum ; the descriptive name was the most frequently used one, then followed by the arbitrary, and the suggestive name. There were only one coined brand name and no generic brand name. 2. The characteristics of descriptive brand name was that, in most cases, it used the name of designer. For the suggestive brand name, it implied the features or the image of its products. For the arbitrary brand name, some bear the ideology or the foundation belief of company itself. 3. For women's wear, the discriptive name appeared most, and followed by arbitrary, and the suggestive name. For bisex wear, the suggestive brand name appeared most, and followed by arbitrary name, and the discriptive name. 4. For descriptive brand name, the names of designer were used most in women's wear brands. Otherwise, the brand names that directly described the image or the characteristics of products were used most in bisex wear brands. For suggestive brand name, soft and feminine images were prevailed in women's wear brand names but comfotable and casual images were dominent in bisexsual brand names. For arbitrary brand name, as the various types of languages were combined and the various meanings and words were mixed, and imply the various meanings in both cases, it was hard to classify the characteristics into some categories.

Case Study on Design Efficiency and Bearing Capacity Characteristics of Bored PHC Piles (PHC 매입말뚝의 설계효율과 지지력 특성 사례분석)

  • Yun, Jung-Mann;Yea, Geu-Guwen;Kim, Hong-Yeon;Choi, Yong-Kyu
    • Journal of the Korean Geosynthetics Society
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    • v.18 no.3
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    • pp.45-53
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    • 2019
  • In this study, it was analyzed the cases of bored PHC piles designed for the building foundations. The overall length of the piles varies within a maximum of 35 m. However, the average length was 17.0 to 18.9 m depending on the kind of the bedrock, with no significant difference. The socket length entered into the bedrock was designed with approximately 58% of the whole piles being 1m, the minimum length of the specification, and up to 5m. Although the range in design efficiency was very large, on average it was about 70%, consistent with the usual known extent. Applications with low design efficiency were mainly shown on the foundation of low-rise buildings or rides with low design load. On the weathered rock, the design load, which governs the design result was widely distributed at 65 to 97% of allowable bearing capacity of ground. The ratio of allowable axial load of piles to allowable bearing capacity of ground is also widely distributed between 36 and 115%, so optimization efforts are required along with design efficiency. On the other hand, the allowable bearing capacity on the soft or hard rock was highly equal, mostly within 90% of the allowable axial load of piles. In the design, the end bearing resistance averaged over 75% of the allowable bearing capacity. However, the results of the dynamic pile load test show that the end bearing resistance was predominant under the E.O.I.D conditions, and in some cases, the end bearing resistance was at least 25% under the restrike conditions.

A Dilemma of Feminist Crime Narrative -focus on Yang Gui-Ja's Romance I Wish For What Is Forbidden (어느 페미니스트 범죄 서사의 딜레마 -양귀자의 『나는 소망한다 내게 금지된 것을』 소고)

  • Lee, Hye-Ryoung
    • Journal of Popular Narrative
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    • v.25 no.4
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    • pp.223-261
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    • 2019
  • This article is a reexamination of the feminist criminal narrative I wish for what is forbidden by Yang Gui-ja in the context of the rise of the women's movement and consumer culture of the middle class in Gangnam in the 1980s and 1990s. At this time, the explosive media culture served to strengthen the ideology that placed the middle-class family at the center as well as the consumption culture. The combination of consumer media culture, women's movement and democratization created a soft and domestic male image while visualizing the material foundation of the middle class in the 1990s of South Korea. In this novel, the domestic male image transforms the feminist criminal narrative into the narrative of the femme fatale attacking the stability and dignity of the middle class family, and at the moment of the transformation, the feminist woman Kang Min-ju is killed by a lower class man who has admired and loved her. This novel is not only current but also signifying as a text that overlaps sociocultural reproduction and feminist issues of the middle class based on Gangnam in the 1990s. This is because it shows the sociocultural context of femicide, such as serial murder of targeting women, as a core code of criminal narrative to be held in Korea since the late 1990s.

Settlement Instrumentation of Greenhouse Foundation in Reclaimed Land (간척지 온실 기초의 침하량 검토)

  • Choi, Man Kwon;Yun, Sung Wook;Yu, In Ho;Lee, Jong-Won;Lee, Si Young;Yoon, Yong Cheol
    • Journal of Bio-Environment Control
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    • v.24 no.2
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    • pp.85-92
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    • 2015
  • This study examined the settlement of a 1-2W type greenhouse using a timber pile, which was recently established on Gyehwa-do reclaimed land, in order to obtain base data for the construction of a greenhouse on reclaimed land. The results of this study are as follows. foundation and timber pile increased over time, irrespective of the interior and exterior of the upon investigation of the ground, it was confirmed that there was no soft rock stratum (bedrock), and that a sedimentary stratum existed under the fill deposit, which is estimated to have been reclaimed during the site renovation. It was also found that a weathered zone was located under the fill deposit and sedimentary stratum, and that the soil texture of the entire ground floor consisted of clay mixed with sand, silty clay, and granite gneiss, in that order, regardless of boreholes. In addition, the underground water level was 0.3m below ground, regardless of boreholes. Despite a slight difference, the settlement of the greenhouse or measurement sites (channels). With regard to the pillar inside the greenhouse, except in the case of CH-2, the data at a site located on the side wall of the greenhouse (wind barrier side) indicated vibrations of relatively larger amplitude. Moreover, the settlement showed a significant increase during a certain period, which was subsequently somewhat reversed. Based on these phenomena, it was verified that the settlement range of each site in the interior and exterior of the greenhouse was between 1.0 and 7.5mm at this time, except in the case of CH-1. The results of the regression analysis indicated good correlation, with the coefficient of determination by site ranging between 0.6362 and 0.9340. Furthermore, the coefficient of determination ranged between 0.6046 and 0.8822 on the exterior of the greenhouse, which is lower than inside the greenhouse, but still indicates significant correlation.