• Proceedings of the KIEE Conference
• /
• 1998.07a
• /
• pp.46-48
• /
• 1998

This paper introduces the design method of a variable reluctace liner pulse motor to be analysed by a 3-dimensional problem in the 2-dimension. And it shows the thrust force density with respect to the ratio of the slot width to the teeth width, the height of mover and the height of tooth.

• Journal of Magnetics
• /
• v.7 no.2
• /
• pp.55-58
• /
• 2002

MR transfer behaviors of the permanent magnet biased spin valve MR sensors with SyAF (synthetic antiferromagnet) layers were studied by micromagnetics modeling. For narrow track MR heads, various height to width ratios were considered together with strength of permanent magnets which stabilities the free layed As the MR sensor width is reduced to $0.12 \mu{m}$, sensor height less than 0.09 ${\mu}{\textrm}{m}$ is needed to show good linearity and the Mr.t of permanent magnets smaller than 0.2 memu/$cm^2$ is sufficient for the domain stabilization. The conditions for single domain behavior of the free layer were also investigated through optimizing the biasing strength of permanent magneto the shield gap and the aspect ratio of MR sensor.

• Atmosphere
• /
• v.17 no.4
• /
• pp.381-391
• /
• 2007

The characteristics of flow around a single obstacle with fixed height and varied length and width are numerically investigated using a computational fluid dynamics (CFD) model. As the obstacle length increases, flow distortion near the upwind side of the obstacle increases and the size of the recirculation zone behind the obstacle also increases. As the obstacle width increases, the size of the recirculation zone decreases, despite almost invariable flow distortion near the upwind side of the obstacle. Flow passing through an obstacle is separated, one part going around the obstacle and the other crossing over the obstacle. The size of the recirculation zone is determined by the distance between the obstacle and the point (reattachment point) at which both the flows converge. When the obstacle width is relatively large, flows are reattached at the obstacle surface and their recoveries occur. Resultant shortening of the paths of flows crossing over and going around decreases the size of the recirculation zone. To support this, the extent of flow distortion defined based on the change in wind direction is analyzed. The result shows that flow distortion is largest near the ground surface and decreases with height. An increase in obstacle length increases the frontal area fraction of flow distortion around the obstacle. In the cases of increasing the width, the frontal area fraction near the upwind side of the obstacle does not change much, but near the downwind side, it becomes larger as the width increases. The frontal area fraction is in a better correlation with the size of the recirculation zone than the building aspect ratios, suggesting that the frontal area fraction is a good indicator for explaining the variation in the size of the recirculation zone with the building aspect ratios.

• The KSFM Journal of Fluid Machinery
• /
• v.13 no.3
• /
• pp.30-36
• /
• 2010

The detailed heat transfer coefficients on a rotating dimpled channel were measured by the hue detection based the transient liquid crystal technique. The dimples were fabricated on the one side of the channel and the tested channel aspect ratio was 4, 6, and 12 with fixed channel width. Tested Reynolds number based on the channel hydraulic diameter was varied from 21,000 to 47,000. A stationary case and two different rotating conditions were tested so that the dimple fabricated surface became leading or trailing surface. For all rotating conditions, the minimum averaged heat transfer coefficient was measured for the channel aspect ratio of 6. Generally, the highest averaged heat transfer coefficient was observed for the highest aspect ratio cases due to increased dimple induced vortex strength.

• Earthquakes and Structures
• /
• v.25 no.2
• /
• pp.135-148
• /
• 2023

The structure-soil-structure interaction (SSSI) effect in adjacent structures may affect the liquefaction-induced damage of shallow foundation structures. The existing studies only analysed the independent effects on the structural dynamic response but ignored the coupling effect of height difference and distance of adjacent structures (F) on liquefied foundations on the dynamic response. Therefore, this paper adopts finite element and finite difference coupled dynamic analysis method to discuss the effect of the F on the seismic response of shallow foundation structures. The results show that the effect of the short structure on the acceleration response of the tall structure can be neglected as F increases when the height difference reaches 2 times the height of the short structure. The beneficial effect of SSSI on short structures is weakened under strong seismic excitations, and the effect of the increase of F on the settlement ratio gradually decreases, which causes a larger rotation hazard. When the distance is smaller than the foundation width, the short structure will exceed the rotation critical value and cause structural damage. When the distance is larger than the foundation width, the rotation angle is within the safe range (0.02 rad).

• International Journal of Air-Conditioning and Refrigeration
• /
• v.6
• /
• pp.158-167
• /
• 1998

Natural convection heat transfer in a rectangular enclosure is investigated numerically for low aspect ratio(height/width) cavities. Numerical results are obtained for aspect ratios between ${10}^{-2}$ and ${10}^0$, Rayleight numbers from ${10}^3$ to ${10}^7$ and Prandtl numbers from 10$^{-2}$ to 10$^3$. Results are compared with existing analytical and experimental results. A heat transfer correlation is developed to predict the mean Nusselt number as a function of the three governing dimensionless parameters: Rayleigh number, aspect ratio and Prandtl number.

• International Journal of Naval Architecture and Ocean Engineering
• /
• v.3 no.2
• /
• pp.150-158
• /
• 2011

Present study aims to investigate the influence of relative breakwater width W/L (W=width of breakwater, L=wavelength), wave steepness $H_i/gT^2$ (Hi=incident wave height, T=wave period) and relative wave height d/W (d=water depth) on forces in the moorings of horizontal interlaced multi-layered moored floating pipe breakwater (HIMMFPB) model. Studies were conducted on scaled down physical models having three layers of Poly Vinyl Chloride (PVC) pipes, wave steepness $H_i/gT^2$ varying from 0.063 to 0.849, relative width W/L varying from 0.4 to 2.65 and relative spacing S/D=2 (S=horizontal centre-to-centre spacing of pipes, D=diameter of pipes). Peak mooring forces were also measured and data collected is analyzed by plotting non-dimensional graphs depicting variation of $f_s/{\gamma}W^2$ ($f_s$=Sea side Mooring force, ${\gamma}$=specific weight of water) & $f_l/{\gamma}W^2$ ($f_l$=Lee side Mooring force) with $H_i/gT^2$ for d/W varying from 0.082 to 0.276 and also variation of $f_s/{\gamma}W^2$ and $f_l/{\gamma}W^2$ with W/L for $H_i$/d varying from 0.06 to 0.400.

• Journal of Korean Neurosurgical Society
• /
• v.60 no.5
• /
• pp.504-510
• /
• 2017

Objective : To investigate the morphological and hemodynamic parameters associated with middle cerebral artery (MCA) bifurcation aneurysm rupture. Methods : A retrospective study of 67 consecutive patients was carried out based on 3D digital subtraction angiography data. Morphological and hemodynamic parameters including aneurysm size parameters (dome width, height, and perpendicular height), longest dimension from the aneurysm neck to the dome tip, neck width, aneurysm area, aspect ratio, Longest dimension from the aneurysm neck to the dome tip (Dmax) to dome width, and height-width, Bottleneck factor, as well as wall shear stress (WSS), low WSS area (LSA), percentage of LSA (LSA%) and energy loss (EL) were estimated. Parameters between ruptured and un-ruptured groups were analyzed. Receiver operating characteristics were generated to check prediction performance of all significant variables. Results : Sixty-seven patients with MCA bifurcation aneurysm were included (31 unruptured, 36 ruptured). Dmax (p=0.008) was greater in ruptured group than that in un-ruptured group. D/W (p<0.001) and the percentage of the low WSS area ($0.09{\pm}0.13$ vs. $0.01{\pm}0.03$, p<0.001) were also greater in the ruptured group. Moreover, the EL in ruptured group was higher than that in unruptured group ($6.39{\pm}5.04$ vs. $1.53{\pm}0.86$, p<0.001). Multivariate regression analysis suggested D/W and EL were significant predictors of rupture of MCA bifurcation aneurysms. Correlation analyses revealed the D/W value was positively associated with the EL (R=0.442, p<0.01). Conclusion : D/W and EL might be the most two favorable factors to predict rupture risk of MCA bifurcation aneurysms.

• Journal of the Korean Society of Tobacco Science
• /
• v.4 no.2
• /
• pp.23-30
• /
• 1982

Six flue- cured cultivars of Nicotiana tabacum L., 15 possible $F_1$ hybrids and $F_2$ Populations among them, and 15 haploid Populations from Fl hybrids and haploids from Parents, were evaluated. Comparisons of the $F_1$, hybrids and $F_2$ Populations with the Parents indicated that heterosis values were small but significant for yield, plant height, days to flower, leaf length and width and total alkaloids from-6.0% to 5.4% in $F_1$ hybrids, and from -3.4% to 3.6% for Plant height days to flower leaves per plant in $F_2$ populations, respectively. There were positive correlations for yield, plant height, days to flower, leaves per plant and total alkaloids between diploid and haploid populations. Increase or decrease ratio of haploids to diploids of total alkaloids was appeared to 30.3%. Those for yield, leaf length and width, value arid reducing sugar were ranged from -4.1% to -27.6%.

• Journal of the Korean Geosynthetics Society
• /
• v.14 no.1
• /
• pp.51-58
• /
• 2015

The counter weight filling is a technology to accumulate soils on the side of berm with a proper width and height for improving the stability of the embankment. This study aims to assess a feasibility of the counter weight filling in the construction of pavement roads for recovery of shear failure during the construction. An effective counter weight filling section was suggested using the numerical analysis. The results showed that the effective counter weight filling section is two-fold (x2) higher than the ratio of width in counter weight filling : embankment height and one third (1/3) to the ratio of height in counter weight filling : embankment height. Also a range of effective trench crossing the counter weight filling required when a trench crossing counter weight filling is installed was suggested by supplying a proper distance between the counter weight filling section and cross-sectional trench.