• Design & Manufacturing
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• 제10권2호
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• pp.12-17
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• 2016

Recently, lightweight material is attracting attention as a solution to the problem of fuel efficiency and increasing the need for development. CFRP has been attracting attention as lightweight materials for automobile because it has a high specific stiffness and specific strength compared to steel material. CFRP have a wide range of mechanical properties depending on the laminate condition. In this paper, study on the forming analysis of double-dome model was performed considering CFRP prepreg laminate condition and coefficient of friction. After forming analysis, the result has compared with wrinkling area and vertical strain of fiber to the laminated condition. And then compared with inflow of blank to the laminate condition. Through this paper, we propose the forming analysis methods of CFRP material.

• 한국생물공학회:학술대회논문집
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• 한국생물공학회 2003년도 생물공학의 동향(XII)
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• pp.577-581
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• 2003

Streptomyces lividans is one of the most commonly-used streptomyetes strain as a molecular cloning and expression host. Unlike its close relative S. coelicolor, however, S. lividans rarely produces secondary metabolite such as actinorhodin in a typical glucose-containing culture condition due to insufficient expression of some antibiotic regulatory genes including afsR2. Although multiple copies of afsR2 or a glycerol-specific culture condition stimulated actinorhodin production in S. lividans, both failed to stimulate actinorhodin production in S. lividans cultured in a typical glucose-containing medium. To generate a culture-condition-independent actinorhodin-overproducing S. lividans strain the afsR2 gene was integrated into the S. lividans TK21 chromosome via homologous recombination, followed by the genetic confirmation. This S. lividans strain produced a significant amount of actinorhodin in both glucose-containing liquid and plate cultures, with higher actinorhodin productivity compared to the S. lividans containing multiple copies of afsR2. These results suggest that a chromosomal integration of a single copy of an antibiotic regulatory gene is a promising method for the development of a stable antibiotic-overproducing streptomycetes strain.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2004년도 춘계학술발표회
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• pp.823-830
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• 2004

Consolidation tests under various deformation modes were performed to investigate the effect of deformation modes on the coefficient of consolidation in the normally consolidated clay in remolded and undisturbed clay. The degree of soil anisotropy was evaluated using cross-anisotropic elasticity theory suggested by Graham et al.(1983). Experimental results showed that the vertical compressibility was larger than the horizontal compressibility by $12{\sim}21%$ for the remolded clay and by $23{\sim}60%$ for the undisturbed clay, respectively. The results of a series of consolidation tests under the specific deformation modes showed that the coefficient of consolidation under 1 dimensional vertical strain condition was larger than that under 3 dimensional strain condition due to different deformation mode. Furthermore, the coefficient of consolidation under 1 dimensional vertical strain condition was larger than that under 1 dimensional horizontal strain condition by $40{\sim}60%$ in undisturbed clay, which clearly emphasized the significant effect of soil anisotropy on the rate of consolidation. Consequently, it can be concluded that the anisotropic deformation modes of soils, especially naturally deposited clays, should be taken into account for more accurate evaluation of the coefficient of consolidation.

• KSBB Journal
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• 제6권4호
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• pp.351-361
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• 1991

This study is on the investigation of hydrogen production and substrate removal by photosynthetic bacteria. After using of Rhodospillum rubrum KS-301 and IFO 3986, which are photosynthetic bacteria as strains, R. rubrum KS-301 was turned out a better strain. And result of experiment in which glucose and sodium lactate, components of wastewater, were used limiting substrates, showed that the productivity of hydrogen was indifferent with the kind of substrates. In batch experiments using free cells and immobilized whole cells, the decrease in hydrogen productivity was observed in the latter case. From the results of these experiments, specific growth rate of cells, specific utilization rate of glucose, and specific production rate of hydrogen were calculated. And each rate was expressed in the form of Monod equation of which parameters were estimated. Also the optimum condition of hydrogen production for free cells was $30^{\circ}C$, pH 7, and 12,000 Lux, and the optimum immobilized condition was as follows: initial immobilized cell concentration 1.0g/L, sodium alginate concentration 2% and light intensity 12,000 Lux.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2002년도 춘계학술대회 논문집
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• pp.66-69
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• 2002

In the ideal forming theory(1), which has been deviously developed as a direct method for optimizing forming process, material elements are required to deform following the minimum plastic work path (or the proportional true strain path). Besides the general theory(2,3), specific ideal forming theories have been developed for membrane sheet forming(4) as well as two-dimensional steady bulk forming(5-7). In this work, the ideal forming theory was successfully applied for non-steady bulk forming under the plane strain condition. Here, the shape change complying with the minimum plastic work path, was effectively described by developing a numerical code based on the characteristic method. Numerical results obtained for a specific industrial part also include the optimum pre-forming shape and its evolving shape change to the final shape as well as the boundary traction history.

• 한국농공학회논문집
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• 제55권2호
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• pp.1-8
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• 2013

This study was performed for the purpose of analyzing the effect of tide on the stress-strain behavior in the boundary surface of sea dike embankment. Tide is a dynamic condition, but there are not suitable numerical models to solve the dynamic embankment condition caused by tide. So the analysis was simplified to quasi dynamic as follow. First, seepage by tide was analyzed according to elapsed time, and the results of the analysis at every hour during one periodic cycle time of 12 hours were applied to the pore water pressure conditions of stress-strain analysis with hyperbolic model by Duncan and Chang. The place at which maximum shear strain took place in the analysis result moved up and down repeatedly along the boundary of the dredged sand fill section and the crashed stone filter section. The value of maximum shear strain was large at high water level of tide. This result means that contraction and relaxation occur in turn repeatedly at every specific position along the boundary, and the repeated action compact loose position with sand moved down from the upper position by gravity. The experiment with the small sea dike model showed the result consistent with the numerical analysis. The surface of sea side on the dike collapsed at high water level after a couple of repetition of the rising and falling of water.

• 한국의류산업학회지
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• 제9권3호
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• pp.347-350
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• 2007

To analyse basic properties for making packing batt according to doubling condition, packing batt yarn, of $300^D$, $900^D$, $3600^D$ made from DTY yarn $150^D$/48 were produced from KTDI. The results are as follows: The birefringence of the sample yarn increased with increasing the annealing temperature and denier. The initial modulus of the sample yarn decreased with increasing the annealing temperature and denier. The higher than annealing temperature of $160^{\circ}C$, initial modulus of the sample are equilibrated. The strain recovery ratio of samples decreased with increasing the annealing temperature and denier. The lower than annealing temperature of $140^{\circ}C$, strain recovery ratio of the sample are decreased Where the $900^D$, $3600^D$ yarns are at $100^{\circ}C$ the specific bending rigidity value obtained is 0.65kgf/d but the twisted yarn (3,600) obtained 0.006 ($gfcm^2/tex^2$). However, where the heat temperature is $160^{\circ}C$, specific bending rigidity value obtained 0.003($gfcm^2/tex^2$).

• 한국운동역학회지
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• 제15권1호
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• pp.155-176
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• 2005

There is some evidence that one of major factors to produce plantar fasciitis depends on the magnitude of the foot arch strain. The orthotics that can reduce the foot arch strain during locomotion may be effective to prevent or treat plantar fasciitis. Therefore, the purpose of this study was to investigate the effect of control condition and three types of foot orthotics on 3-dimensional foot arch strain that can produce plantar fasciitis during treadmill level and uphill walking and running. Sixteen male subjects are recruited and the arch length and height strain according to three types of foot orthotics with respect to control condition were measured by using two digital video cameras. The first hypothesis which the comfort of foot orthotics would be increased from arch pad, half length orthotics to full length orthotics was mostly accepted. It suggested that the types of the foot orthotics could be properly prescribed according foot regions that is pain or abnormal. The second hypothesis which the foot arch strain can be reduced by foot orthotics during level heel-toe walking and running and the third hypothesis which the foot arch strain can be reduced by foot orthotics during uphill heel-toe walking and running were rejected. The foot arch length and height strain during walking and running showed small and subject-specific characteristics and could not be optimal biomechanical variable to prove the overall comfort. The forth hypothesis which the foot arch strain cannot be reduced by foot orthotics during uphill toe walking and running was accepted. With the foot arch length and height strain during uphill toe walking and running the windlass mechanism suggested by Hicks can be explained successfully and excessive uphill toe walking and running can be one of cause of plantar fasciitis. The dynamic investigation on the foot arch such as walking and running should be carefully observed with integrated insights considering ligaments and foot bones as well as plantar fascia, extrinsic muscles and tendons, and intrinsic muscles and tendons.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2005년도 춘계학술대회 논문집
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• pp.411-414
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• 2005

It is reported that $\varepsilon$ (HCP) and $\gamma$ (FCC) phases of a Fe-17Mn alloy transform to $\alpha'$ phase, which has BCC structure, under a deformation condition. In this study, we investigated the effect of strain-induced-transformed $\alpha'$ phase on sliding wear of the Fe-17Mn alloy that originally had e and y phases. Wear tests of the materials were carried out using a pin-on-disk wear tester at various loads of 0.5N-50N under a constant sliding speed condition of 0.38m/s against glass $(83\%\;SiO_2)$ beads. The sliding distance and radius were loom and 9 mm, respectively. Wear rate of the Fe-17Mn alloy was calculated by dividing the weight loss, measured to the accuracy of $10^{-5}g$ by the measured specific gravity and sliding distance. Worn surface and wear debris of the specimens were examined using an SEM and XRD. During the wear, $\alpha'$ phase of BCC structure was formed by strain-induced transformation when the applied wear load exceeded critical values. The $\alpha'$ phase formed by the strain induced transformation increased the wear rate of the Fe-17Mn alloy.

• Advanced Composite Materials
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• 제17권2호
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• pp.139-156
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• 2008

This study aims to characterize the dynamic tensile strength of unidirectional carbon/epoxy composites. Two different carbon/epoxy composite systems, the unidirectional T700S/2500 and TR50S/modified epoxy, are tested at the static condition and the strain rate of $100\;s^{-1}$. A high-strain-rate test was performed using a tension-type split Hopkinson bar technique with a specific fixture for specimen. The experimental results demonstrated that both tensile strength increase with strain rate, while the fracture behaviors are quite different. By the use of the rosette analysis and the strain transformation equations, the strain rate effects of material principal directions on tensile strength are investigated. It is experimentally found that the shear strain rate produces the more significant contribution to strain rate effect on dynamic tensile strength. An empirical failure criterion for characterizing the dynamic tensile strength was proposed based on the Hash-in's failure criterion. Although the proposed criterion is just the empirical formula, it is in better agreement with the experimental data and quite simple.