• The Bulletin of The Korean Astronomical Society
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• v.35 no.2
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• pp.48.2-48.2
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• 2010

Quiescent filaments are bigger, more stable, and longer lived than active region filaments. So, the shape of a quiescent filament changes little during its lifetime and a fast motion of plasma rarely occurs. But when it is dynamically influenced by external phenomena, a rapid motion of plasma may temporarily occur. By analyzing the motion of plasma we can infer some of the magnetic structure permeating such an excited quiescent filament. We analyzed the H$\alpha$ images of a quiescent filament in the northern hemisphere that was observed at Big Bear Solar Observatory on 2004 August 2, and found that: 1) the filament was excited by a flare that occurred in a remote active region located in the southern hemisphere, 2) By this excitation, a part of the filament moved vertically upward and horizontally out of main body, and then it stayed there without much motion. Then after it moved vertically downward and horizontally to the main body, 3) the final position of plasma, however, was not the same as the initial position, being about 14Mm above it. We suggest that the filament was initially in a more or less static equilibrium. The excitation of the filament broke the initial equilibrium, and then brought about a new one that is different from the original one. Since the filament should have magnetic field, it is likely that both the equilibria may have been maintained by diplike magnetic structures. Furthermore, the transition from one equilibrium to another as we inferred should have accompanied a permanent change of magnetic configuration as well.

• Journal of computational fluids engineering
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• v.17 no.3
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• pp.53-58
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• 2012

Steady flow simulations through a high pressure turbine guide vanes were carried out. The main objective of the present work is to study the performance of turbulence models on the steady flow prediction from aerodynamic and aerothermal points of view. Three turbulence models were compared, namely SST, k-${\omega}$ and ${\omega}$-Reynolds stress models. The laminar results were also compared. The comparison was done with emphasis on the isentropic Mach number and heat transfer coefficient along the blade, and total pressure loss in the wake region. The calculated isentropic Mach number showed reasonable agreement with experimental data along the blade surface for all three turbulent models. For the total pressure loss in the wake region, ${\omega}$-Reynolds stress model showed the best agreement with the experimental data. However, unless using an appropriate transition model, the heat transfer coefficients of all three turbulent models showed poor agreement with experimental data.

• Proceedings of the KSME Conference
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• 2000.04a
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• pp.25-30
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• 2000

Residual stresses induced in U-bending and tube-to-tubesheet joining processes of PWR's steam generator row-1 tube were measured by X-ray method and Hole-Drilling Method(HDM). The stresses resulting from the Internal pressure and the temperature gradient in the steam generator were also estimated theoretically. In U-bent lesions, the residual stresses at extrados were induced with compressive stress(-), and its maximum value reached -319 MPa in axial direction at ${\psi}=0^{\circ}$ in position. Maximum tensile residual stress of 170MPa was found to be at the flank side at Position of${\psi}=90^{\circ}$, i.e., at apex region. In tube-to-tubesheet fouling methods, the residual stresses induced by the explosive joint method were found to be lower than that by the mechanical roll method. The gradient of residual stress along the expanded tube was highest at the. transition region, and the residual stress in circumferential direction was found to be higher than the residual stress in axial direction. Hoop stress due to an internal pressure between primary and secondary side was analyzed to be 76 MPa and thermal stress was 45 MPa.

• The Journal of Asian Finance, Economics and Business
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• v.7 no.4
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• pp.317-324
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• 2020

The study aims to analyze the theoretical background of the economic growth and sustainable development; systematization of scientists view on monitoring and economic and innovative evaluation, analysis and diagnosis of factors affecting these processes. Rating characteristics of the level of innovative resources development obtained based on the comparative analysis of Kazakhstan regions. Calculations were done based on official statistics during 2010 and 2015-2017. Based on obtained data there has been grading of the country regions and their ratings were determined by the level of development of innovative resources. This research identifies areas and mechanisms to ensure balanced sustainable development of the national economy. The findings suggest that sustainable development of the state is affected by the innovative activity of the regions, the sustainable development of which is ensured by innovative enterprises. Transition to the model of sustainable territorial development involves the formation of such conditions and the use of mechanisms under which the natural base of this development is not destroyed, the environment suitable for human existence is preserved and reproduced. The findings of this research support for pursuing a national policy of reducing regional imbalances, and promoting a more balanced and sustainable development of the whole country.

• Transactions of the Korean Society of Mechanical Engineers
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• v.9 no.5
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• pp.555-563
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• 1985

Two-dimensional turbulent wake flow behind a circular cylinder is investigated experimentally by suing linearized constant temperature hot wire anemometer. Turbulent fluctuations and mean velocity defects are measured in the rage of 5 dia.- 500 dia. downstream from the cylinder and for the Reynolds numbers of 2000-4000. Results with statistical treatment and digital data processing techniques are as follows: (1) The transition region from near wake to far wake is 30 dia. - 50 dia. downstream from the cylinder. (2) In the near wake, it is found that strong periodic ( f=845Hz) coherent structure exists. (3) It shows that the inertial subrange is 180Hz-2000Hz in self preservation region.

• Proceedings of the Korean Vacuum Society Conference
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• 2010.08a
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• pp.114-114
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• 2010

In this study, structural properties and photoluminescent characteristics of thin film rhombohedral zinc orthosilicate doped with manganese ($Zn_2SiO_4:Mn$) were investigated. The $Zn_2SiO_4:Mn$ films showed a pronounced absorption edge in the near ultraviolet wavelength region and a high optical transparency in the visible spectral range. The maximum transmittance reached 0.922 at 597 nm, which was very close to the transmittance of the fused quartz substrate alone (0.935). The $Zn_2SiO_4:Mn$ films were composed of rhombohedral polycrystalline grains with random crystallographic orientation. The broad-band photoluminescence emission peaked at around 525 nm was observed from the $Zn_2SiO_4:Mn$ films, which was ascribed to the radiative relaxation from the $^4T_1$ lowest excitation state to $^6A_1$ ground state of 3d5 electrons in divalent manganese ion. The excitation band exhibited a peak maximum at 259 nm in the near ultraviolet region, which was considered to be associated with the charge transfer transition of divalent Mn ion in the $Zn_2SiO_4$ system.

• Journal of the Society of Naval Architects of Korea
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• v.53 no.1
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• pp.54-61
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• 2016

This paper defines the design constraint in consideration of the dynamic characteristics and stability in the longitudinal direction of a supercavitating vehicle. Available range of the design variables is calculated by numerical simulation and the cavity modeling of vehicle dynamics is performed first. Configuration parameters of the supercavitating vehicle to determine the vehicle dynamics and characteristics of the cavity are defined as design variables. Design constraints are supercavitation, trim velocity, stability and vehicle dynamics in transition phase. Numerical results show that in accordance with the change of the design variables, the proposed design constraints reflect the physical characteristics of the supercavitating vehicle. This research finds the design region where the constraints of supercavity and the trim velocity are satisfied, and the stability analysis refines the design results by excluding the region where the stability is not guaranteed. The stability analysis is particularly important for a vehicle with the short fin span.

• Journal of the Korean Magnetics Society
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• v.5 no.3
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• pp.165-170
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• 1995

NMR measurement has been studied for protons in pre-polarized flowing water by a separated detector working at high field far away from the measured field region where the transition of protons is occurred by the pertur-bation of RF energy. The conditions for NMR signal were optimized on the amplitude and frequency of modulation field, the RF field of detector, water speed, and RF field at the measured field region. The NMR signal with the full width of 320 nT at the half maximum in Lorentzian curve and with signal to noise ratio of 10.5 was measured in the range from a few ${\mu}T$ to mT, and its shape and amplitude were independent of the measured field intensity and its uniformity.

• Korea-Australia Rheology Journal
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• v.19 no.1
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• pp.35-42
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• 2007

The effects of particle size distribution on the magnetorheological response of inverse ferrofluids was investigated using controlled mixtures of two monodisperse non-magnetisable powders of sizes $4.6\;{\mu}m\;and\;80{\mu}m$ at constant volume fraction of 30%, subjected to large amplitude oscillatory shear flow. In the linear viscoelastic regime (pre-yield region), it was found that the storage and loss moduli were dependent on the particle size as well as the proportion of small particles, with the highest storage modulus occurring for the monodisperse small particles. In the nonlinear regime (post yield region), Fourier analysis was used to compare the behaviour of the $1^{st}\;and\;3^{rd}$ harmonics ($I_{1}\;and\;I_{3}\;respectively$) as well as the fundamental phase angle as functions of the applied strain amplitude. The ratio of $I_{3}/I_{1}$ was found to become more pronounced with decreasing particle size as well as with increasing proportion of small particles in the bidisperse mixtures. Furthermore, the phase angle was able to clearly show the transition from solid-like to viscous behaviour. The results suggested that the nonlinear response of a bidisperse IFF is dependent on particle size as well as the proportion of small particles in the system.

• Journal of the Korean Vacuum Society
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• v.16 no.4
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• pp.273-278
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• 2007

For the simulation of active region in the quantum cascade lasers (QCL), we solved Schrodinger equation utilizing Runge-Kutta method and Shotting method. Wavelength, phonon resonant energy, and dipole matrix element were simulated with the variation of active region thickness. As a result of such simulation, it was suggested the tolerance range of epi-layer thickness error when 3-quantum well QCL structures are grown.