• Proceedings of the Korea Concrete Institute Conference
• /
• 2003.05a
• /
• pp.561-566
• /
• 2003

In this study, to predict the behavior of RC beam strengthened with Carbon fiber reinforced polymer(CFRP) plate, analytical program considering material non-linearity is developed. Strain compatibility and force equilibrium are applied and internal forces of constitutive material are calculated using nonlinear stress-strain relationship. Also, to certainty the reliability of analytical program, deflection, strain of CFRP plate, change of neutral axis on cross section and crack distribution at failure are compared with those of experiment, and each results are almost coincident.

• Advances in nano research
• /
• v.6 no.4
• /
• pp.323-337
• /
• 2018

The nonlinear free vibration of a nanorod subjected to finite strain is investigated. The governing equation of motion in material configuration in terms of displacement is determined. By means of Galerkin method, the Fourier series solutions satisfying some typical boundary conditions are determined. The amplitude-frequency relationship and interaction between the modes are studied. The effects of nonlocal elasticity are shown for different length of nanotubes and nonlocal parameter. The results show that nonlocal effects lead to additional internal modal interaction for nanorod vibrations.

• Interaction and multiscale mechanics
• /
• v.1 no.2
• /
• pp.303-315
• /
• 2008

In this paper, thermodynamical properties of crystalline silicon under strain are calculated using classical molecular dynamics (MD) simulations based on the Tersoff interatomic potential. The Helmholtz free energy of the silicon crystal under strain is calculated by using the ensemble method developed by Frenkel and Ladd (1984). To account for quantum corrections under strain in the classical MD simulations, we propose an approach where the quantum corrections to the internal energy and the Helmholtz free energy are obtained by using the corresponding energy deviation between the classical and quantum harmonic oscillators. We calculate the variation of thermodynamic properties with temperature and strain and compare them with results obtained by using the quasi-harmonic model in the reciprocal space.

• Proceedings of the Korean Society For Composite Materials Conference
• /
• 2003.10a
• /
• pp.150-153
• /
• 2003

Longitudinal strains({$varepsilon}_x$) of the core and skin layers in glass fiber reinforced plastic(GFRP) cross-ply composite laminates have been studied using the embedded optical fiber sensor of totally-reflected extrinsic Fabry-Perot interferometer(TR-EFPI). Foil-type strain gauges bonded on both the upper and lower surfaces were used for the measurement of the surface strains. Both TR-EFPI sensor and strain gauge bonded on the specimen surface showed excellent agreement within -0.0086 ~ +0.0302% strain. It was shown that values of {$varepsilon}_x$ in the interior of the surface layer and the core layer measured by embedded TR-EFPI sensor was significantly higher than that of the specimen surface measured by strain gauges. The experimental results were ascertained with finite element analysis. Embedded TR-EFPI optical fiber sensor could measure accurately the internal strains which were different from the surface.

• Entomological Research
• /
• v.48 no.5
• /
• pp.339-347
• /
• 2018

Seven different strains of Beauveria bassiana were used in a bioassay on Pieris rapae larvae. The results showed that an B. bassiana strain showed relatively high pathogenicity towards P. rapae larvae. The adjusted mortality rate was 92.86 %, and the infection rate was 85.71 % in 10 days post inoculation. Molecular identification was performed to identify the unknown strain. Internal Transcribed Spacer sequence analysis showed that the polymerase chain reaction amplicon length of the unknown strain of Beauveria sp. was 573 bp, and sequence similarity to the known B. bassiana sequences in the NCBI database was 99 %. The B. bassiana strain was named Bb01. The changes of proteins and PPO of P. rapae larvae infected by B. bassiana Bb01 strain at different times was determined. The activity of PPO increased in 1-6 d and decreased in 7 d again after inoculation. The B. bassiana invaded into the insect body affected the balance of the proteins and PPO.

• Journal of Cardiovascular Imaging
• /
• v.31 no.3
• /
• pp.142-144
• /
• 2023

• Journal of the Korean Society of Manufacturing Process Engineers
• /
• v.17 no.4
• /
• pp.130-136
• /
• 2018

In this paper, the effects of different 3D printing parameters including laminated angle and annealing temperature, were observed for their effects on tensile testing. In 3D printing, a filament is heated quickly, extruded, and then cooled rapidly. Because plastic is a poor heat conductor, it heats and cools unevenly causing the rapid heating and cooling to create internal stress within the printed part. Therefore, internal stress can be removed using annealing and to increase tensile strength and strain. During air cooling at annealing temperature $140^{\circ}C$, the strain of laminated angle $45^{\circ}$ specimens tended to increase by 46% while the tensile stress tended to increase by 7.4%. During oven cooling at annealing temperature $140^{\circ}C$, the strain of laminated angle $45^{\circ}$ specimens tended to increase by 34% while the tensile stress tended to increase by 22.2%. In this study, we found "3D printing with annealing" eliminates internal stress and increases the strength and stiffness of a printed piece. On the microstructural level, annealing reforms the crystalline structures to even out the areas of high and low stress, which created fewer weak areas. These results are very useful for making 3D printed products with a mechanical strength that is suitable for applications.

• Nuclear Engineering and Technology
• /
• v.10 no.2
• /
• pp.73-78
• /
• 1978

The effect of temperature and strain rate on the deformation behavior of $\alpha$-uranium was investigated in the temperature ranged 300$^{\circ}$ to 55$0^{\circ}C$ by strain, rate change test. Strain rate sensitivity, activation volume, strain rate sensitivity exponent and dislocation velocity exponent were determined. The strain rate sensitivity exponent and dislocation velocity exponent were determined. The strain rate sensitivity exponent increases with strain below 40$0^{\circ}C$, while the exponent decreases with strain above 50$0^{\circ}C$. It is believed that the increase of strain rate sensitivity exponent with strain below 40$0^{\circ}C$ can be attributed to an increase in internal stress as a result of work hardening while decrease of the exponent with strain above 50$0^{\circ}C$ is due to predominance of thermal softening over work hardening because more slip, system are active in deformation above about 50$0^{\circ}C$.

• Journal of the Korean Crystal Growth and Crystal Technology
• /
• v.9 no.1
• /
• pp.64-69
• /
• 1999

Polyacrylonitrile(PAN)-based carbon fiber tows were heat-treated by the internal resistance heating method under the certain load. To consider the strain behavior of the fiber tows during heat-treatments, 1200~$2200^{\circ}C$, strain changes of those were measured. It was observed that the larger longitudinal strain was induced under the larger stretching stress. The changes in the strain are different from the temperature regions below and above $1700^{\circ}C$. Obtained apparent activation energies under the stretching stresses of 70 and 322 MPa from time-strain curves were 67.46 and 52.27kJ$mol^{-1}$, respectively. Therefore, it was known that the larger stretching stresses effectively reduce the apparent activation energy of the fiber structure development of the fiber tows.

• Journal of Microbiology and Biotechnology
• /
• v.9 no.6
• /
• pp.870-872
• /
• 1999

The ubiquinone and G+C contents of the bioflocculant-producing fungus, a new Aspergillus strain, were detennined using high-perfonnance liquid chromatography. The internal transcribed spacers 1 and 2 (ITS1 and ITS2), and the 5.8S ribosomal DNA (rDNA) of the strain were amplified and sequenced. The strain contained ubiquinone-l0($H_2$)as a major quinone and the G+C content was 49 mol%. A phylogenetic analysis of the ITS regions indicated that the strain belonged to the genus Aspergillus according to its previously classified morphological characteristics. Based on a sequence homology search, the strain was most closely related to Petromyces muricatus (anamorph, A. muricatus; accession number, AJ005674). The sequence of a new Aspergillus strain in ITS1 and ITS2, and 5.8S rDNA showed 97% homology to P. muricatus. Therefore, the strain is believed to be a new bioflocculant-producing Aspergillus strain.