• Korean Journal of Materials Research
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• v.24 no.11
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• pp.610-616
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• 2014

In this study, we investigated the precipitation behavior of the R-phase precipitated at the initial stage of aging and its effect on the pitting corrosion of 25%Cr-7%Ni-4%Mo super duplex stainless steel. The R-phase in super duplex stainless steel was mainly precipitated at the interface of ferrite/austenite phases and inside of the ferrite phase during the initial stage of aging, and it was transformed into the ${\sigma}$-phase with an increase in aging time. The ferrite phase was decomposed into a new austenite phase and ${\sigma}$-phase. The R phase was an intermetallic compound, which represented a lower Ni and higher Mo than the matrix, and also had a higher Mo and Cr concentration than the ${\sigma}$ phase. With an increasing aging time, the pitting potential $E_p$ was increased slowly by the precipitation of the R-phase, and it was then steeply decreased by the precipitation of the ${\sigma}$-phase. The R-phase was decreased the pitting potential, but its effect was smaller than effect of ${\sigma}$-phase.

• 한국신재생에너지학회:학술대회논문집
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• 2006.11a
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• pp.241-244
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• 2006

The present paper describes the scale effect correction method for wind turbine by using CFD(computational fluid dynamics). For the correct ions of wind turbine scale effect, various researches on the helicopter rotor scale effect were Investigated and feasibility study of methods was performed to correct wind turbine scale effect The present paper also introduces new scale effect correction method based on two dimensional lift slope modification. In order to test the Present method, performance analyses of NREL Phase VI wind turbines under various scale conditions were carried out by using CFD. The present method showed reasonable results when applied to NREL Phase VI wind turbine.

• Asian-Australasian Journal of Animal Sciences
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• v.23 no.2
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• pp.169-174
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• 2010

A meta-analysis was conducted to summarize the results of studies which have described the profiles of hormones during the oestrous cycle in buffalo using a fixed effect model and a random effect model. Plasma progesterone concentrations were lowest (0.30${\pm}$0.06 ng/ml) during the peri-oestrous phase and increased (p = 0.067) through the early luteal phase to a maximum concentration (1.94${\pm}$0.03 ng/ml) during the mid-luteal phase. Circulating plasma inhibin and estradiol concentrations were lowest (0.31${\pm}$0.01 and 11.04${\pm}$0.13 ng/ml) during the mid-luteal phase, increased through the late luteal phase to maximum concentrations (0.44${\pm}$0.02 and 22.48${\pm}$0.32 ng/ml) during the peri-oestrous phase. Plasma FSH concentrations were lowest during the early luteal phase and increased through the mid-luteal phase to a maximum concentration during the peri-oestrous phase. Peripheral prolactin concentrations were lowest during the late luteal phase and increased to a maximum concentration during the peri-oestrous phase which then declined (p = 0.716) during the early luteal phase. Peripheral plasma cortisol concentrations decreased from 2.68${\pm}$0.14 ng/ml during the early luteal phase to 1.43${\pm}$0.27 ng/ml during the mid-luteal phase (p<0.001) which then increased to 2.06${\pm}$0.17 ng/ml during the late luteal phase. Plasma $T_{5}$ concentrations decreased from the late luteal phase to the peri-oestrous phase (p<0.001) which then increased during the early luteal phase. $T_{4}$ concentrations increased from the late luteal phase to the peri-oestrous phase which then decreased during the early luteal phase.

• Proceedings of the KWS Conference
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• 2003.11a
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• pp.216-218
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• 2003

Most of ferrous b.c.c weld materials may experience martensitic transformation during rapid cooling after welding. And it is well known that volume expansion due to phase transformation could influence in the case of welding of high tensile strength steels on the relaxation of welding residual stress. To apply this effect practically, it is a prerequisite to establish a numerical model which is able to estimate the effect of phase transformation on residual stress relaxation quantitatively. In this study, we investigated the effect of phase transformation on the relaxation of welding residual stress through experiment. And three-dimensional thermal elastic-plastic FEM analysis is conducted to compare the effect of phase transformation on the relaxation of welding residual stress in high strength steels(POSTEN60, POSTEN80) with analytical results which is not considering the effect of phase transformation on residual stress relaxation. According to the results, the extents of welding residual stress relaxation due to phase transformation in the case of welding of POSTEN60, POSTEN80 are 0.85 $\sigma$/$\sigma$$\sub$Y0/, 0.75$\sigma$/$\sigma$$\sub$Y0/, respectively.

• Journal of Biomedical Engineering Research
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• v.20 no.2
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• pp.165-172
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• 1999

An enhancement technique for phase dependent image contrast in MRI(Manetic Resonance Imaging) is proposed. Because the method can enhance inherent phase contrast it is suited for susceptibility imaging and flow imaging where intravoxel phase is a source of image contrast. In this paper, applying external phase in the voxel enhances phase contrast. The external phase is generated by a tailored RF pulse so that one can control the phase contrast and even produces phase only contrast. Signal intensity due to both inherent phase and external phase is analyzed and the proposed technique is applied to a susceptibility effect only imaging and a flow effect only imaging. To verify the proposed technique, computer simulations are performed and their results are given.

• The Bulletin of The Korean Astronomical Society
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• v.42 no.2
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• pp.63.3-64
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• 2017

KIC6118779 is an over-contact binary system having a short orbital period of about 0.36 days. The photometric data for this system are acquired by the observations of Kepler mission in the long cadence mode having a time resolution of about 30 minutes. It means that the Kepler light curves of the system may be strongly affected by phase smearing effect and the analysis of them without consideration of the phase smearing effect may result in wrong stellar properties. Additionally, this system also shows dynamical variation of light curve resulting from spot activity. For all those reasons, it is difficult to investigate KIC6118779, and the investigation should be carried out carefully. In this presentation, we introduce the phase smearing effect and carry out the light curve modeling with the 2015 version of the Wilson-Devinney binary code considering the phase smearing effect. Our results show that the system is a deep over contact binary system and has extremely low mass ratio of about 0.12. Moreover our spot modeling implies the cyclic migration of a big cool spot on the massive component.

• Proceedings of the Membrane Society of Korea Conference
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• 1996.04a
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• pp.55-56
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• 1996

Heterophase polymer system has been attractive for a potential applicability to gas separation membrane material. It has been known that there is a trade-off between gas permeability and its selectivity in common polymers. Therefore, the heterophase polymer can be an alternative for a gas separation membrane material because its transport properties can be readily controlled by blending of two different polymers. The transport properties of immiscible polymer blends strongly depend upon the intrinsic transport properties of corresponding polymers. Another important factor to determine the transport properties is their morphology: volume fraction, size and shape of dispersed phase. Although the effect of the volume fraction of the dispersed phase on the transport properties has been widely investigated, the size and shape effects have been paid attention very much. In an immiscible polymer blend of two polymers, its morphology is primarily controlled by its volume fraction of dispersed phase. Therefore, the effect of the size of the dispersed phase can be hardly seen. Therefore, a block copolymer has been commonly employed to control their morphology when each block is miscible with one or the other phase. In this work, gas transport properties will be measured by varying the morphology of the heterophase polymer membrane. The transport properties will be interpreted in terms of their morphology. The effect of the volume fraction of the PI phase and, in particular, its size effect will be investigated experimentally and theoretically.

• Journal of Korea Foundry Society
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• v.9 no.1
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• pp.58-66
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• 1989

The effect of heat treating temperature and ${\alpha}$ phase In the ${\beta}$ phase matrix were investigated for ${\beta}-CuZnAl$ shape memory alloys by tension test, fatigue test, and shape memory effect test. After heat treatment at $677^{\circ}C$, $750^{\circ}C$, $800^{\circ}C$ and $850^{\circ}C$ for 10 min. respectively, static fracture stress(${\sigma}_f$), fatigue fracture stress(${\tau}_{max}$) at $10^6$ cycle, and elongation(${\epsilon}_f$) was $24.2kg/mm^2$, $17.21kg/mm^2$ and 11.8%, respectively. As heat treating temperature decreased, fracture surfaces of the specimens were changed from the intergranular to the transgranular fracture mode. Especially, the a phase precipitated in the ${\beta}$ phase matrix had an effect on crack propagation and the fracture surface was characterized by dimple-like pattern when crack propagated in transgranular cracking mode. Precipitation of the ${\alpha}$ phase in the ${\beta}$ phase matrix lowered the transformation temperature by $10^{\circ}C$, and about 2.5 vol.% ${\alpha}$ phase did not affect the shape memory effect examined by the bending test.

• New & Renewable Energy
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• v.3 no.3
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• pp.54-62
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• 2007

The present paper describes the scale effect correction methods for scaled NREL Phase VI wind turbines by using CFD[computational fluid dynamics). For the corrections of wind turbine scale effect, various researches on the helicopter rotor scale effect were investigated and the feasibility study of the methods was performed to correct wind turbine scale effect. The present paper also introduces scale effect correction methods based on two dimensional lift slope. In order to test the present method, performance analyses of NREL Phase VI wind turbines under various scale conditions were carried out and new correction method was applied. Granting that the new correction method is valid only above Reynolds No. 100,000, it showed reasonable agreement between model and full scale wind turbines in the linear torque region.

• Transactions of the Korean Society of Mechanical Engineers
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• v.7 no.4
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• pp.398-403
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• 1983

In this investigation, the effect of microstructural factors on the impact energy was studied, using dual phase steels with soft phase of ferrite encapsulated by hard phase of martensite. It was found that the effect of the ferrite grain size on the impact energy decreases as the strength ratio increases, these results are due to the micro-brittlefracture facet by the difficulty of cleavage crack formation in the ferrite grain.