• Title/Summary/Keyword: Plastic index

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Nonlinear Compression Characteristics of Highly Plastic Clays and Silts (고소성점토 및 실트의 비선형 압밀특성)

  • Han, Dae-Hee;Im, Jong-Chul;Kwon, Jung-Keun
    • Proceedings of the Korean Geotechical Society Conference
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    • 2008.10a
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    • pp.1081-1089
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    • 2008
  • Highly plastic clays in their normally consolidated state are not linear but are concave upwards. Thus their compression index deceases with the increase in consolidation pressure. Likeness the e - log ${\sigma}\;_{\upsilon}\;'$ curves of the silts are not linear but are convex upwards. In this paper, conducted consolidation test with four undisturbed field soil and found that their e - log ${\sigma}\;_{\upsilon}\;'$ plots are not linear. And analyzed difference of settlement between computed value with compression index($C_c$) and computed value with improved compression index($\mathbb{C}$).

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Finite Element Analysis on the Small Scale Yielding of a Crack Tip in Plane Stress (平面應力狀態 에서 균열先端 의 小規模降伏 에 관한 有限要素解析)

  • 임장근;맹주성;김병용
    • Transactions of the Korean Society of Mechanical Engineers
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    • v.7 no.3
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    • pp.270-277
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    • 1983
  • Plastic plane stress solutions are given for a center cracked strip, characterized by the Ramberg-Osgood plastic index, under bi-axial tension. Using a power law hardening stress-strain relation, an incremental plasticity finite element formulation is developed, and simple formulation is given for computing J-integral with nodal displacements. The near tip angular distribution of von Mises effective stress doesn't differ significantly in magnitude according to the change of loading stress and bi-axial load combination factor. But, for smaller plastic index, the location of its maximum value moves vertically at a head of crack. J-integral value, in the plastic zone near crack tip, decreases with load combination factor for large and small plastic index.

Energy-based damage index for steel structures

  • Bojorquez, E.;Reyes-Salazar, A.;Teran-Gilmore, A.;Ruiz, S.E.
    • Steel and Composite Structures
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    • v.10 no.4
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    • pp.331-348
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    • 2010
  • Ample research effort has been oriented into developing damage indices with the aim of estimating in a reasonable manner the consequences, in terms of structural damage and deterioration, of severe plastic cycling. Although several studies have been devoted to calibrate damage indices for steel and reinforced concrete members; currently, there is a challenge to study and calibrate the use of such indices for the practical evaluation of complex structures. The aim of this paper is to introduce an energy-based damage index for multi-degree-of-freedom steel buildings that accounts explicitly for the effects of cumulative plastic deformation demands. The model has been developed by complementing the results obtained from experimental testing of steel members with those derived from analytical studies regarding the distribution of plastic demands on several steel frames designed according to the Mexico City Building Code. It is concluded that the approach discussed herein is a promising tool for practical structural evaluation of framed structures subjected to large energy demands.

The Oblique Extended Reverse First Dorsal Metacarpal Artery Perforator Flap for Coverage of the Radial-Volar Defect of the Proximal Interphalangeal Joint in the Index Finger: A Case Report

  • Jeeyoon Kim;Bommie Florence Seo;Junho Lee;Sung No Jung
    • Archives of Plastic Surgery
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    • v.49 no.6
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    • pp.760-763
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    • 2022
  • The dorsal metacarpal artery perforator flap is a flap that rises from the hand dorsum. Owing to its reliability and versatility, this flap is used as a workhorse for finger defect. However, to cover the radial-volar defect of the proximal interphalangeal joint (PIPJ) of the index finger, a longer flap is required than before. Here, we introduce the oblique extended reverse first dorsal metacarpal artery (FDMA) perforator flap to cover the radial-volar aspect defect of the index finger. A 45-year-old man got injured to the radial-volar defect of PIPJ of the left index finger caused by thermal press machine. The wound was 2 × 1 cm in size, and the joint and bone were exposed. We used FDMA perforator from anastomosis with palmar metacarpal artery at metacarpal neck. Since the defect was extended to the volar side, the flap was elevated by oblique extension to the fourth metacarpal base level. The fascia was included to the flap, and the flap was rotated counterclockwise. Finally, PIPJ was fully covered by the flap. Donor site was primarily closed. After 12 months of operation, the flap was stable without complication and limitation of range of motion. The oblique extended reverse FDMA perforator flap is a reliable method for covering the radial-volar defect of the PIPJ of the index finger. This flap, which also has an aesthetic advantage, will be a good choice for hand surgeons who want to cover the PIPJ defect of the index finger using a nonmicrosurgical option.

A Fundamental Study on Evaluation of Corrected Compression Index by Plasticity Index in Marine Clayey Soils (해성 점성토의 소성지수에 따른 보정압축지수 평가에 관한 기초연구)

  • Park, Seong-Bak;Lee, Kang-Il;Seo, Se-Gwan
    • Journal of the Korean Geosynthetics Society
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    • v.17 no.3
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    • pp.9-18
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    • 2018
  • The soil parameters important for the design of the soft ground are the compression index ($C_c$), the consolidation settlement and consolidation speed at the field. Compression index is obtained by laboratory consolidation test. In the laboratory consolidation test, sample disturbance always occurs. In order to correct the disturbance phenomena, the method of calculating the compression index proposed by Schmertmann (1955) is generally used. However, recent developments in sampling technology and Korean soil conditions are different from those proposed by Schmertmann. So it needs to be verified. In this study, each consolidation curve's cross void ratio is evaluated by doing consolidation test varying disturbance on high-plastic clay (CH), low-plastic clay (CL) and low-plastic silt (ML). The test results were $0.521e_0$ for low-plastic silt, $0.404e_0$ for low-plastic clay, and $0.458e_0$ for the high-plastic clay. This results were different from those of Schmertmann's suggested value of $0.42e_0$. Therefor we proposed a correction formula using the plastic index according to soil type. However, since the results of this study are limited test results, further studies on various korean soil are needed to suggest the compression index correction method according to the degree of plasticity index of soil.

Nonlinear Compression Characteristics of Highly Plastic Clays and Silts of Korea South Coast (한국 남부 해안 고소성 점토 및 실트의 비선형 압축특성 연구)

  • Hong, Seok-Woo;Im, Jong-Chul
    • Journal of Navigation and Port Research
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    • v.36 no.3
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    • pp.181-187
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    • 2012
  • Highly plastic clays in their normally consolidated states are not always linear but are concave downwards. Thus their compression index deceases with the increase of consolidation pressure. The $e-{\log}{\sigma}_{\upsilon}{\prime}$ curves of plastic or non-plastic silty clays are not linear but are convex upwards. In this paper, consolidation tests were conducted with several undisturbed field soils of Korea south coast and their $e-{\log}{\sigma}_{\upsilon}{\prime}$ plots are not always linear. In case of using Butterfield's method(liquid limit 50~100%), ${\ln}{\upsilon}-{\ln}{\sigma}_{\upsilon}{\prime}$ plots are linear. But some undisturbed samples which have void ratio over 2.24, liquid limit over 100% and plasticity index over 60% are not linear. In results of consolidation tests with remolded samples which contain silt(fly ash) contents of 90% has compression index increasing with the increase in consolidation pressure.

Heterodigital Free Flap of Index Finger Amputee for Coverage of the Long Finger Soft Tissue Defect - A Case Report -

  • Hwang, So-Min;Kim, Jang Hyuk;Kim, Hong-Il;Jung, Yong-Hui;Kim, Hyung-Do
    • Archives of Reconstructive Microsurgery
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    • v.22 no.2
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    • pp.82-85
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    • 2013
  • If the replantation on the original position is not possible, the amputated tissue of a hand may be used as a donor for recovering hand functions at other positions. This procedure is termed 'heterodigital replantation'. An 63-year-old male patient who was in press machine accident came to Our Hospital. He had large dorsal soft-tissue defects ($5{\times}3cm$) on his left long finger and complete amputation on his left index finger through the proximal interpharyngeal joint. Replantation was not indicated because crushing injury of index finger was severe. So we decided to use index finger soft tissue as heterodigital free flap for the coverage of the long finger defect. The ulnar digital artery and dorsal subcutaneous vein of the free flap were anastomosed with the radial digital artery and dorsal subcutaneous vein of the long finger. The heterodigital free flap provided satisfactory apperance and functional capability of the long finger. The best way to treat amputation is replantation. But sometimes surgeon confront severely crushed or multi-segmental injured amputee which is not possible to replant. In this situation, reconstructive surgeons should consider heterodigital free flap from amputee as an option.

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Elasto-plastic Analysis of Circular Tunnel with Consideration of Strain-softening of GSI Index (GSI 지수의 변형률 연화를 고려한 원형터널의 탄소성 해석)

  • Lee, Youn-Kyou;Park, Kyung-Soon
    • Tunnel and Underground Space
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    • v.20 no.1
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    • pp.49-57
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    • 2010
  • For the elasto-plastic analysis of a circular tunnel driven in a strain-softening rock mass subjected to a hydrostatic in-situ stress condition, this study suggests a convenient elasto-plastic analysis scheme which takes the strain-softening of GSI index into account and demonstrates its potential as a numerical tool in designing a circular tunnel. The suggested numerical scheme was developed by modifying the previous elasto-plastic procedure proposed by Lee & Pietruszczak(2008). With the assumption that GSI index of rock mass adjacent to the tunnel surface may be degraded due to the damage caused by the blasting and excavation, the concept of the strain-softening of GSI index was invoked. The concept provides a useful tool considering the strain-softening of the strength parameters appearing in the generalized Hoek-Brown criterion because these parameters can be evaluated empirically by use of GSI. In order to check the validity of the proposed scheme, the elasto-plastic analyses for circular tunnels were performed in various analysis conditions and the results were discussed.

Utility of Toe-brachial Index for Diagnosis of Peripheral Artery Disease

  • Park, Seong-Chul;Choi, Chang-Yong;Ha, Young-In;Yang, Hyung-Eun
    • Archives of Plastic Surgery
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    • v.39 no.3
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    • pp.227-231
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    • 2012
  • Background : The ankle brachial pressure index (ABI) is a simple, useful method for diagnosing peripheral artery disease (PAD). Although the ABI is an objective diagnostic method, it has limited reliability in certain scenarios. The aim of the present study was to determine the accuracy and reliability of the toe brachial index (TBI) as a diagnostic tool for detecting stenosis in PAD, associated with normal or low ABI values. Methods : ABI and TBI values were measured in 15 patients with diabetic gangrene who were suspected of having lower extremity arterial insufficiency. The ABI and TBI values were measured using a device that allowed the simultaneous measurement of systolic blood pressure in the upper and lower extremities. In addition, the ABI and TBI values were compared pre- and post-angiography. Results : Patients with an ABI of 0.9-1.3 showed almost no difference between the 2 measurements. The patients with TBI >0.6 had no arterial insufficiency. The patients with TBI <0.6 required vascular intervention with ballooning. After the angiography, the gangrenous wounds decreased in size more rapidly than they did prior to the intervention. Conclusions : Our findings suggest that TBI is the method of choice for evaluating lower limb perfusion disorders. This result requires further studies of TBI in a larger number of patients. Future long-term studies should therefore evaluate the utility of TBI as a means of screening for PAD and the present findings should be regarded as preliminary outcomes.