• 한국지반공학회:학술대회논문집
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• 한국지반공학회 1999년도 연약지반처리위원회 학술세미나
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• pp.36-47
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• 1999

Terzaghi's theory of one-dimensional consolidation is restricted in its applicability to relatively thin layers and small incremental loading. Because it is assumed to infinitesimal strain and linear material function. For this reason, Gibson et al established a rigorous formulation for the one-dimensional nonlinear finite strain consolidation theory. There are some difficulties in the application of finite strain consolidation theory. The developed program consisted of several forms and modules. These forms and modules with graphic-user-interfaced format are used in analysis of consolidation practices. For the purpose of verification of developed program. the results of case study and prediction of developed program are compared. The results of comparison is fairly well with prediction and measured data. And with varying finite strain consolidation parameter, g(e) or λ(e), the sensitivity of predicted values were examined.

• Korea-Australia Rheology Journal
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• 제16권4호
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• pp.213-218
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• 2004

Linear high-density polyethylene (PE) was controlled to induce strain-hardening behavior by introducing a small amount of second component with an anisotropic structure. In order to form an anisotropic structure in the PE matrix, the polymer was extruded through a twin-screw extruder, and the structure was controlled by varying the extrusion conditions. Depending on conditions, the second component formed a film, thread and droplet structure. If the second component was kept rigid, the morphology evolution could be delayed and the second component could maintain its film or thread structure without further relaxation. In par­ticular, the second component of the thread structure made a physical network and gave rise to remarkable strain hardening behavior under high extension. This study suggests a new method that induces strain hard­ening behavior by introducing a physically networked second component into the linear polymer melt. This result is anticipated to improve the processibility of linear polymers especially when extensional flow is dominant, and to contribute to our understanding of strain hardening behavior.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2001년도 봄 학술발표회 논문집
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• pp.239-244
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• 2001

Natural clayey soils or improved grounds are in a overconsolidated conditions due to changes in vertical stress and pore pressures, desiccation, ageing and so on. These grounds show inelastic stress-strain behaviour characteristics within all range of strain except very small strain (${\gamma}$$\_$s/$\leq$10￣$^3$∼10￣$^4$%) when construction, such as excavations and retaining walls, is performed. Also it strongly depends on loading rate of current stress path and recent stress path. This study carried out drained stress path tests by varying loading rate of current and recent stress path. Test results indicated that stress-strain behaviour of overconsolidated clay depends on loading rate, especially loading rate of current stress path.

• Coupled systems mechanics
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• 제5권4호
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• pp.305-314
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• 2016

We utilize first-principles calculations within density-functional theory to investigate the possibility of strain engineering in the tuning of the band structure of two-dimensional $MoS_2$. We find that the band structure of $MoS_2$ monolayers transits from direct to indirect when mechanical strain is applied. In addition, we discuss the change in the band gap energy and the critical stains for the direct-to-indirect transition under various strains such as uniaxial, biaxial, and pure shear. Biaxial strain causes a larger change, and the pure shear stain causes a small change in the electronic band structure of the $MoS_2$ monolayer. We observe that the change in the interaction between molecular orbitals due to the mechanical strain alters the band gap type and energy.

• 소성∙가공
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• 제28권3호
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• pp.154-158
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• 2019

The hole expansion tests using conical punch, flat punch or hemispherical punch are widely used for stretch flangeability verification of HSS. In this study, we investigate the strain distribution on the shear edges of the hole expansion test using grid marking and a projector. A small crack at the edge is distributed, resulting in a large gap between the HER and the crack strain. The strain distribution at the edges is irregular due to anisotropy of sheet metal. While an edge perpendicular to the rolling direction indicate a lower strain level compared to an edge parallel to the rolling direction, edge cracks occur at the edge perpendicular to the rolling direction. To predict the manifestation of edge cracks in FE analysis, the result of the hole expansion test with a crack strain measurement may well be a better tool than FLD. In this case, the level of strain and the direction of the edge relative to the rolling direction should be well considered.

• 대한전기학회논문지:전기물성ㆍ응용부문C
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• 제55권8호
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• pp.381-386
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• 2006

In this study, we have investigated electrical and mechanical properties of semiconducting materials for power cable caused by CNT. Specimens were made of sheet form with the four of specimens for measurement. Volume resistivity of specimens was measured by volume resistivity meter after 10 minutes in the pre-heated oven of both $23{\pm}\;1\;[^{\circ}C]\;and\;90{\pm}\;1\;[^{\circ}C]$. And stress-strain of specimens was measured by TENSOMETER 2000. A speed of measurement was 200[mm/min], ranges of stress and strain were 400[Kgf/Cm2] and 600[%]. From this experimental results, the volume resistivity had different properties because of PTC/NTC tendency at between $23[^{\circ}C]\;and\;90[^{\circ}C]$. Also volume resistivity was low by increasing the content of CNT. It means that a small amount of CNT has a excellent electrical properties. And stress was increased, while strain was decreased by increasing the content of CNT. Thus, we could know that a small amount of CNT has a excellent electrical and mechanical oroperties.

• 대한수의학회지
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• 제47권2호
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• pp.169-174
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• 2007

To provide information for the molecular pathogenesis and antigenic structures of Korean isolates of porcine epidemic diarrhea virus (PEDV), the small membrane (sM) protein gene of Chinju99 strain, which was previously isolated from piglets suffering from severe diarrhea was characterized and further analyzed with other PEDV strains. The sM gene of Chinju99 generated by reverse transcription and polymerase chain reaction had a single open reading frame with 231 bases consisting of 24.2% adenine, 18.6% cytosine, 18.1% guanine and 39.0% thymine nucleotides. Nucleotide sequence of the gene revealed 97.8% homology to those of Belgian strain CV777 and British strain Br1/87, and 97.0% to Chinese strain LZC. The gene encoded a protein with 76 amino acids, and putative amino acid sequence of the gene revealed 98.7% homology to those of CV777 and Br1/87, and 96.1% to LZC. The amino acids of Chinju99 sM gene consisted of mostly hydrophobic residues, and there were one potential N-myristylation site and one potential threonine (T)-linked phosphorylation site recognized. Also, there was a transmembrane region with 46 amino acids, and Chinju99 was more close to CV777 and Br1/87 than to LZC in phylogenetic analysis on the sM amino acid sequences.

• Parasites, Hosts and Diseases
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• 제59권3호
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• pp.319-324
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• 2021

Incidence of tsutsugamushi disease (scrub typhus) caused by Orientia tsutsugamushi, is steadily increasing. It is a mite-borne disease transmitted by chigger mites. In this study, the chigger mites were collected from field small mammals in Hwaseong-si (city), Gyeonggi-do (province), Korea, 2019 and 2020. The field small mammals captured were 56 Apodemus agrarius (94.9%) and 3 Crocidura lasiura (5.1%). A total of 7,531 chigger mites were collected from the captured small mammals. Using PCR test, 153 chigger mite pools were examined and 17 pools were reported positive for O. tsutsugamushi. The O. tsutsugamushi were identified to 5 strains; Jecheon strain was most prevalent, followed by Boryong strain. The other strains were OI011, Taguchi, and Shimokoshi. Collectively, these results provide essential regional information on mite-borne tsutsugamushi disease in the Hwaseong-si, and further contribute to bring awareness and rapid diagnosis for the tsutsugamushi disease.

• 한국항만학회지
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• 제14권4호
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• pp.463-473
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• 2000

Reinforcement with geotextiles have been used in the foundation soil to enhance the resistance of embankments to avoid failure through excessive deformation or shear in the foundation. It is improtant to know the amount of the strain and the displacement of buried geotextiles for the verification of the reinforcement behaviour. Full scale trial constructions were performed to check the deformational characteristics of the polyester(PET) mat which was used for the embankment reinforcement. Many instrumentation equipments including surface settlement plates, profile gauges and inclinometer casings were installed to observe the behaviour of the soft ground due to the soil embankment. 60 electrical resistance strain gauges and 9 vibrating wire LVDTs were installed 세 measure the deformation of the polyester mat. Results of various tests and geotextile, waterproofing and protection from the hazard environments were introduced. The proposed instrumentation method was effective for the monitoring or the geotextile behaviour. The direct attachment of electrical resistance strain gauges on the gertextile mat was able to measure small changes of the strain of geotextiles. At the end of the 5 month monitoring, 54 of 60 (93%) strain gauges and 7 of 9 (78%) displacement transducers survived all perils of the compaction impacts and the humidity. And the tensile strain of grotextiles increased as the ground displacement became larger. Though the observed strain of mats under the 3m high embankment load was less than 1%, the magnitudes of the strain according to the mat spreading method were different from each other.

• Geomechanics and Engineering
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• 제18권3호
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• pp.225-234
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• 2019

A numerical stepwise approach for cavity expansion problem in strain-softening rock or soil mass is investigated, which is compatible with Mohr-Coulomb and generalized Hoek-Brown failure criteria. Based on finite difference method, plastic region is divided into a finite number of concentric rings whose thicknesses are determined internally to satisfy the equilibrium and compatibility equations, the material parameters of the rock or soil mass are assumed to be the same in each ring. For the strain-softening behavior, the strength parameters are assumed to be a linear function of deviatoric plastic strain (${\gamma}p^*$) for each ring. Increments of stress and strain for each ring are calculated with the finite difference method. Assumptions of large-strain for soil mass and small-strain for rock mass are adopted, respectively. A new numerical stepwise approach for limited pressure and plastic radius are obtained. Comparisons are conducted to validate the correctness of the proposed approach with Vesic's solution (1972). The results show that the perfectly elasto-plastic model may underestimate the displacement and stresses in cavity expansion than strain-softening coefficient considered. The results of limit expansion pressure based on the generalised H-B failure criterion are less than those obtained based on the M-C failure criterion.