• 대한수학회지
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• 제53권3호
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• pp.597-621
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• 2016

We present regularity conditions for suitable weak solutions of the Navier-Stokes equations with slip boundary data near the curved boundary. To be more precise, we prove that suitable weak solutions become regular in a neighborhood boundary points, provided the scaled mixed norm $L^{p,q}_{x,t}$ with 3/p + 2/q = 2, $1{\leq}q$ < ${\infty}$ is sufficiently small in the neighborhood.

• Membrane and Water Treatment
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• 제11권5호
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• pp.353-361
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• 2020

The present study deals with a numerical investigation of heat and mass transfer in a Sweeping Gas Membrane Distillation (SGMD) used for desalination. The governing equations expressing the conservation of mass, momentum, energy and species with coupled boundary conditions were solved numerically. The slip boundary condition applied on the feed saline solution-hydrophobic membrane interface is taken into consideration showing its effects on profiles and process parameters.The numerical model was validated with available experimental data and was found to be in good agreement particularly when the slip condition is considered. The results of the simulations highlighted the effect of slip boundary condition on the velocity and temperature distributions as well as the process effectiveness. They showed in particular that as the slip length increases, the permeate flux of fresh water and process thermal efficiency rise.

• 자원환경지질
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• 제33권1호
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• pp.61-75
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• 2000

Through modeling fault network using thin plate finite element technique in the San Andreas Fault system with slip rate over 1mm/year, as well as elevation, heat flow, earthquakes, geodetic data and crustal thickness, we compare the results with velocity boundary conditions of plate based on the NUVEL-1 plate model and the approximation of deformation in the Great Basin region. The frictional and dislocation creep constants of the crust are calculated to reproduce the observed variations in the maximum depth of seismicity which corresponds to the temperature ranging from $350^{\circ}C$ to $410^{\circ}C$. The rheologic constants are defined by the coefficient of friction on faults, and the apparent activation energy for creep in the lower crust. Two parameters above represent systematic variations in three experiments. The pattern of model indicates that the friction coefficient of major faults is 0.17~0.25. we test whether the weakness of faults is uniform or proportional to net slip. The geologic data show a good agreement when fault weakness is a trend of an additional 30% slip dependent weakening of the San Andreas. The results of study suggest that all weakening is slip dependent. The best models can be explained by the available data with RMS mismatch of as little as 3mm/year, so their predictions can be closely related with seismic hazard estimation, at least along faults where no data are available.

• Safety and Health at Work
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• 제9권1호
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• pp.17-24
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• 2018

Background: Increasing the slip resistance of floor surfaces would be desirable, but there is a lack of evidence on whether traction properties are linearly correlated with the topographic features of the floor surfaces or what scales of surface roughness are required to effectively control the slipperiness of floors. Objective: This study expands on earlier findings on the effects of floor surface finishes against slip resistance performance and determines the operative ranges of floor surface roughness for optimal slip resistance controls under different risk levels of walking environments. Methods: Dynamic friction tests were conducted among three shoes and nine floor specimens under wet and oily environments and compared with a soapy environment. Results: The test results showed the significant effects of floor surface roughness on slip resistance performance against all the lubricated environments. Compared with the floor-type effect, the shoe-type effect on slip resistance performance was insignificant against the highly polluted environments. The study outcomes also indicated that the oily environment required rougher surface finishes than the wet and soapy ones in their lower boundary ranges of floor surface roughness. Conclusion: The results of this study with previous findings confirm that floor surface finishes require different levels of surface coarseness for different types of environmental conditions to effectively manage slippery walking environments. Collected data on operative ranges of floor surface roughness seem to be a valuable tool to develop practical design information and standards for floor surface finishes to efficiently prevent pedestrian fall incidents.

• 대한기계학회논문집B
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• 제24권6호
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• pp.860-869
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• 2000

Numerical and experimental investigations are performed for the molecular transition and slip flows in pumping channels of a disk-type drag pump. The flow occurring in the pumping channel develops from the molecular transition to the slip flow traveling downstream. Two different numerical methods are used in this analysis: the first one is a continuum approach in solving the Navier-Stokes equations with slip boundary conditions, and the second one is a stochastic approach through the use of the direct simulation Monte Carlo method. In the experimental study, the inlet pressures are measured for various outlet pressures in the range of 0.1{\sim}4Torr. From the present study, the numerical results of predicting the performance, obtained by both methods, agree well with the experimental data for the range of Knudsen number $Kn{\leq}0.1$ (i.e., the slip flow regime). But the results from the second method only agree with the experimental data for Kn>0.1(i.e., the molecular transition regime)

• 한국지구과학회지
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• 제23권1호
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• pp.87-96
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• 2002

Aeromagnetic and gravity data were analyzed to delineate the subsurface structure of the Yeongdong basin and its related fault movement in the Okcheon fold belt. The aeromagnetic data of the total intensity (KIGAM, 1983) were reduced to the pole and three dimensional inverse modeling, which considers topography of the survey area in the modeling process, were carried out. The apparent susceptibility map obtained by three dimensional magnetic inversion, as well as the observed aeromagnetic anomaly itself, show clearly the gross structural trend of the Yeongdong basin in the direction on between $N30^{\circ}E$ and $N45^{\circ}E$. Gravity survey was carried out along the profile, of which the length is about 18.2 km across the basin. Maximum relative Bouguer anomaly is about 7 mgals. Both forward and inverse modeling were also carried out for gravity analysis. The magnetic and gravity results show that the Yeongdong basin is developed by the force which had created the NE-SW trending the magnetic anomalies. The susceptibility contrast around Yeongdong fault is apparent, and the southeastern boundary of the basin is clearly defined. The basement depth of the basin appears to be about 1.1 km beneath the sea level, and the width of the basin is estimated to be 7 km based on the simultaneous analysis of gravity and magnetic profiles. There exists an unconformity between the sedimentary rocks and the gneiss at the southeastern boundary, which is the Yeongdong fault, and granodiorite is intruded at the northwestern boundary of the basin. Our results of gravity and magnetic data analysis support that the Yeongdong basin is a pull-apart basin formed by the left-stepping sinistral strike-slip fault, which formed the Okcheon fold belt.

• 한국철도학회논문집
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• 제10권2호
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• pp.224-230
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• 2007

The performance and applicability of FDS code is analyzed for flow simulation in railway tunnel. FDS has been built in NIST(USA) for simulation of fire-driven flow. RANS and DNS's results are compared with FDS's. AJL non-linear ${\kappa}-{\epsilon}$[7,8] model is employed to calculate the turbulent flow for RANS. DNS data by Moser et al.[9] are used to prove the FDS's applicability in the near wall region. Parallel plate is used for simplified model of railway tunnel. Geometrical variables are non-dimensionalized by the height (H) of parallel plate. The length of streamwise direction is 50H and the length of spanwise direction is 5H. Selected Re numbers are 10,667 for turbulent flow and 133 for laminar low. The characteristics of turbulent boundary layer are introduced. AJL model's predictions of turbulent boundary layer are well agreed with DNS data. However, the near wall turbulent boundary layer is not well resolved by FDS code. Slip conditions are imposed on the wall but wall functions based on log-law are not employed by FDS. The heavily dense grid distribution in the near wall region is necessary to get correct flow behavior in this region for FDS.

• Journal of Advanced Marine Engineering and Technology
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• 제31권3호
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• pp.272-281
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• 2007

A numerical simulation on nitrogen gas flow in a long parallel plate microchannel was performed to obtain the effect of compressibility and rarefaction on gaseous flow in microchannels. The simulation was based on steady. two dimensional compressible Navier-Stokes and energy equations with noslip and first order slip boundary conditions. The channel was $1.2{\mu}m$ deep and $3000{\mu}m$ long. The Reynolds numbers were in the range of order from $10^{-2}$ to $10^{-1}$. So the flow was assumed to be laminar. The computations were performed on various pressure ratios. The outlet pressure was fixed to atmospheric pressure. The outlet Knudsen number was 0.0585, consequently the flow was in the slip flow regime. The computations were performed with the assumption of isothermal channel walls. The results were compared with the experimental data. The agreement was good.

• Computers and Concrete
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• 제1권1호
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• pp.31-46
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• 2004

A methodology is presented for computing stresses in structural concrete members exposed to fire. Coupled heat and moisture migration simulations are used to establish temperature, pore pressure, and liquid-saturation state variables within near-surface zones of heated concrete members. Particular attention is placed on the use of coupled heat and multiphase fluid flow simulations to study phenomena such as moisture-clogging. Once the state variables are determined, a procedure for combining the effects of thermal dilation, mechanical loads, pore pressure, and boundary conditions is proposed and demonstrated. Combined stresses are computed for varying displacement boundary conditions using data obtained from coupled heat and moisture flow simulations. These stresses are then compared to stresses computed from thermal analyses in which moisture effects are omitted. The results demonstrate that moisture migration has a significant influence on the development of thermal stresses.

• 자원환경지질
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• 제30권5호
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• pp.459-467
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• 1997

In order to examine the primary trends and characteristics of geological lineaments along the southwestern boundary of Okcheon zone, we carried out the analysis of geological lineament trends over six selected sub-areas using Landsat-5 TM images and digital elevation model. The trends of lineaments is determined by a minimum variance method, and the resulting geological lineament map can be obtained through generalized Hough transform. We have corrected look direction biases reduces the interpretability of remotely sensed image. An approach of histogram modification is also adopted to extract drainage pattern specifically in alluvial plains. The lineament extracting method adopted in this study is very effective to analyze geological lineaments, and that helps estimate geological trends associated various with the tectonic events. In six sub-areas, the general trends of lineaments are characterized NW, NNW, NS-NNE, and NE directions. NW trends in Cretaceous volcanic rocks and Jurassic granite areas may represent tension joints that developed by rejuvenated end of the Early Cretaceous left-lateral strike-slip motion along the Honam Shear Zone, while NE and NS-NNE trends correspond to fault directions which are parallel to the above Shear Zone. NE and NW trends in Granitic Gneiss are parallel to the direction of schitosity, and NS-NNE and NE trends are interpreted the lineation by compressive force which acted by right-lateral strike-slip fault from late Triassic to Jurassic. And in foliated Granite, NE and NNE trends are coincided with directions of ductile foliation and Honam Shear Zone, and NW-NNW trends may be interpreted direction of another compressional foliation (Triassic to Early Jurassic) or end of the Early Cretaceous tensional joints. We interpreted NS-NNE direction lineation is related with the rejuvenated Chugaryung Fault System.