• 대한기계학회논문집B
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• 제27권12호
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• pp.1681-1690
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• 2003

The effect of roughness is a change in the velocity and turbulence distributions near the surface. Turbulence models with surface roughness effect are applied to the fully developed flow in a two-dimensional, rough wall channel. Modified wall function model, low-Reynolds number k-$\varepsilon$ model, and k-$\omega$ model are selected for comparison. In order to make a fair comparison, the calculation results are compared with the experimental data. The modified wall function model and the low-Reynolds number k-$\varepsilon$ model require further refinement, while the k-$\omega$ model of Wilcox performs remarkably well over a wide range of roughness values.

• 한국전산유체공학회:학술대회논문집
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• 한국전산유체공학회 2000년도 추계 학술대회논문집
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• pp.15-24
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• 2000

The transient response of an airfoil to a rapidly deploying spoiler is numerically investigated using the turbulent compressible Navier-Stokes equations in two dimensions. Algebraic Baldwin-Lomax model, Wilcox $\kappa-\omega$ model, and SST $\kappa-\omega$ turbulence model are used to calculate the unsteady separated flow due to the rapid spoiler deployment. The spoiler motion relative to a stationary airfoil is treated by an overset grid hounded by a Dynamic Domain-Dividing Line which has been devised by the authors. The adverse effects of the spoiler influenced by the spoiler location and the hinge gap are expounded. The numerical results are in reasonably good agreement with the existing experimental data.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2000년도 추계학술대회논문집B
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• pp.603-608
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• 2000

The characteristics of laminar and turbulent slot impinging jet flows are examined using segregated FEM with SUPG. Turbulent flows are modeled using $Wilcox^{(1)}$ $k-\;{\omega}$ turbulence model. The results are validated by comparing with velocity field of the existing experimental data. The distance of the target plate from the nozzle varies between 2, 4 and 5 times the slot jet width. Present study shows that the $k-\;{\omega}$ model gives results which agree well with the existing experimental data. In turbulence flows, the velocity profile of present calculation is more accurate than the existing numerical calculations. In laminar flows, We found tertiary vortex which was not found in the previous numerical study by M. $chen^{(6)}$ et al due to the numerical difference.

• International Union of Geodesy and Geophysics Korean Journal of Geophysical Research
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• 제23권1호
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• pp.12-17
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• 1995

Space explorations by spacecraft have detected the solar wind and the interplanetary magnetic field (IMF), whose existences had been suggested to explain the narrow comet plasma tail formation before the space age. Thereafter, a global magnetic structure seperating the opposite polarity regions of IMF in the heliosphere was discovered (Wilcox and Ness, 1965). It is called helispheric current sheet (HCS). Comets have been proved as the useful heliospheric probes. Recently, another capability of comet as a probe of HCS was suggested by Yi (1994). In the process of comet plasma tail disconnection events (EDs) showing the ray folding and main tail severance between the folding rays (Brandt, 1982), the folding rays preceding DE might be the visualization of HCS draped around comet, In order to test this new idea, the association of comet Halley 16 DEs with comet crossings of HCS confirmed by spacecraft observations at the time of comet Halley apparition 1985~1986 was investigated.

• 대한화학회지
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• 제40권10호
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• pp.674-677
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• 1996

• Asian-Australasian Journal of Animal Sciences
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• 제4권2호
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• pp.111-120
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• 1991

A study was conducted to determine the macromineral status of grazing cattle in three climatic regions of the province of South Sulawesi, Indonesia. Soil, forage, blood and rib bone samples were collected within the Western, Central and Eastern regions, respectively, in February-March and August-September of 1987. Calcium and magnesium were not deficient in soil samples. For forages, calcium and phosphorus were deficient for all regions and forage sodium was deficient except for the western region in the dry season. Crude protein was deficient during the dry season. The overall percentage of deficient plasma phosphorus samples was 17 or 23% for the wet and dry seasons, respectively. Based on these analyses, macrominerals most likely deficient in both seasons were phosphorus and calcium in all regions, in addition to sodium in the Central and Eastern regions.

• Asian-Australasian Journal of Animal Sciences
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• 제4권2호
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• pp.121-130
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• 1991

Research was conducted to determine the micromineral status of grazing cattle in three climatic regions of the province of South Sulawesi, Indonesia. Soil, forage, blood and liver samples were collected within the Western, Central and Eastern regions in February-March and August-September of 1987. Forages were deficient in copper, selenium and zinc. Serum copper was deficient in all regions but zinc was deficient more in the dry season. Liver copper was deficient in all regions and both seasons except in the central region in the rainy season. Based on the analyses, microminerals most likely deficient in both the rainy and dry seasons for each region were as follows: Western-copper, selenium and zinc; Central-manganese and copper; Eastern-selenium, copper and zinc. Some degree of molybdenum excess was found in the Eastern region.

• International Journal of Aeronautical and Space Sciences
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• 제14권4호
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• pp.387-397
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• 2013

An assessment of two-equation turbulence models, the low Reynolds k-${\varepsilon}$ and k-${\omega}$ SST models, with the compressibility corrections proposed by Sarkar and Wilcox, has been performed. The compressibility models are evaluated by investigating transonic or supersonic flows, including the arc-bump, transonic diffuser, supersonic jet impingement, and unsteady supersonic diffuser. A unified implicit finite volume scheme, consisting of mass, momentum, and energy conservation equations, is used, and the results are compared with experimental data. The model accuracy is found to depend strongly on the flow separation behavior. An MPI (Message Passing Interface) parallel computing scheme is implemented.

• PNF and Movement
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• 제11권1호
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• pp.63-68
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• 2013

Purpose : The purpose of this study was to examine changes in spatiotemporal gait parameters(STGPs) in healthy adults before and after a immediate intervention of a Mulligan taping program(MTP). Methods : A total of 12 healthy adults(mean age, 20.82 years; age range, 19-24 years) participated in the study. performance was assessed by recording changes in the STGPs using GaitRite. comparisons of changes in the STGPs at pre-intervention and at dischange were analyzed using the Wilcox signed rank test and Mann-Whithney U test. Results : There was a significant improvement in the outcome measures of STGPs(stride length, velocity) after immediate of MTP(p<0.05). However, no significant different pre-test and post-test step width, toe angle(p>0.05). Conclusion : Participants in a MTP improves STGPs, thereby increasing the ability of healthy adults to maintain gait. MTP appears to be a safe and efficacious, noninvasive treatment modality for patients with knee joint disease.

• 천문학회지
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• 제56권2호
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• pp.187-194
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• 2023

The remote sensing technique of measuring the magnetic field was applied first to sunspots by Hale (1908). Later Babcock (1961) showed that the solar surface magnetic field on a global scale is a dipole in first-order approximation and that this dipole field reverses once every solar cycle. The Wilcox Solar Observatory (WSO) supplies the spherical harmonics coefficients of the solar corona magnetic field of each Carrington Rotation, calculated based on the remotely-sensed photospheric magnetic field of the solar surface. To infer the internal current system producing the global solar coronal magnetic field structure and evolution of the Sun, we calculate the multipole components of the solar magnetic field using the WSO data from 1976 to 2019. The prominent cycle components over the last 4 solar activity cycles are axis-symmetric fields of the dipole and octupole. This implies that the current inversion driving the solar magnetic field reversal originates from the equatorial region and spreads to the whole globe. Thus, a more accurate solar dynamo model must include an explanation of the origin and evolution of such solar internal current dynamics.