• Proceedings of the KSME Conference
• /
• 2001.06d
• /
• pp.600-604
• /
• 2001

The relation between the aerodynamic diameter and some morphological parameters was studied for flame-generated aggregates. $SiO_{2}$ aggregates were generated from $SiCl_{4}$ in premixed methane/air flames. These aggregates were sampled and classified according to their aerodynamic diameter by a cascade impactor; moreover, computer program was developed and tested to find the equivalent area diameter and the fractal dimension of the aggregates. We calculated the parameters from the digitized images of the aggregate TEM micrographs. The aerodynamic diameters of the sampled aggregates were larger than $0.4{\mu}m$ in this experiment. In most cases, fractal dimension of their projection image was very close to 2.0 for these large aggregates. It was found that the equivalent area diameter of these aggregates was approximately three times larger than the Stokes' diameter of them.

• Proceedings of the Korean Geotechical Society Conference
• /
• 2000.09a
• /
• pp.9-16
• /
• 2000

Applicability of the cross shaped drain in a soft clay ground is examined using the laboratory discharge capacity test, column consolidation test and 3-D numerical flow analysis. The equivalent diameter of the tested drains is back-calculated from the laboratory experiment and compared with those calculated from the formula suggested in the literature. The effective range of the cross shaped drain about the discharge capacity and coefficient of permeability is analyzed. The results of numerical analysis show that the cross shaped drain which has a cross-sectional area twice of the band shaped drain can reduce the consolidation time by 30% from that for the band shaped drain in a soft clay ground that K is over 1${\times}$10$\^$-7/cm/sec

• Journal of the Korean Society for Precision Engineering
• /
• v.21 no.8
• /
• pp.188-195
• /
• 2004

In this paper we analyzed the mechanical behavior with respect to the thickness variation of elastic foundation(fatty tissue) in end-to-end anastomosis. This study considered the preliminary deformed shape induced by suturing in the anastomosis of coronary artery and PTFE with different diameters using simplified suturing model and the fatty tissue surrounding heart and coronary artery for more accurate result using finite element method. Area compliance(CA) was used to analyze the final deformed shape of the anastomotic part with respect to the thickness variation of fatty tissue under mean blood pressure, 100mmHg(13.3㎪). And Equivalent and circumferential stresses in the anastomosis were also analyzed with respect to the change of initial diameter ratio( $R_1$) and fatty tissue thickness( $T_{F}$). The results obtained were as follows : 1 When the elastic foundation, assumed to be incompressive material, surrounded the grafts in anastomosis, the compliance mismatch of artery and PTFE was reduced by 47 -72%. 2. As the initial diameter ratio( $R_1$) became larger, the higher difference of compliance was induced in spite of elastic foundation surrounding grafts. 3. The maximum nondimensional circumferential stress is twice or three times as high as the maximum nondimensional equivalent stress in the anastomotic part.t.

• Asian-Australasian Journal of Animal Sciences
• /
• v.5 no.1
• /
• pp.13-18
• /
• 1992

Three cattle, a sheep and a goat were slaughtered to determine the distribution of digesta particles and mean size of digesta particles. Aliquot samples of digesta in the diverse sites of the digestive tracts were fractionated by a wet sieving technique. Fractionated particles were analyzed by the magnetic grid analyzer system constructed by authors. Results showed that the proportion of particles in digesta was similar among the omasum, abomasums cecum, colon and rectum, but that for the reticulo-ruminal digesta was different from the others. The pattern of the mass base frequency distribution of particles was also similar in the post-ruminal digesta. Average Heywood's diameter (the diameter equivalent to that of a circle with equal area to a projected area of a given particle) was about 1.2 mm in the reticulo-ruminal digesta and decreased to 0.65 mm for cattle or to about 0.35 mm for sheep and goat in the omasal digesta. Average Heywood's diameter was about the same in the post-ruminal digesta. It is concluded that mean particle size and particle distribution in digesta of the rectum or feces reflect those in digesta of the omasum.

• Journal of Welding and Joining
• /
• v.3 no.2
• /
• pp.1-9
• /
• 1985

In this study, the influence of carbon equivalents on friction welds of similar steels was investigated. Four types of steels with 15mm diameter tested in the wide range of carbon equivalents from 0.3 to 1.1 Main experimental results are summarized as follows : (1) Under the constant burn-off length, the friction time becomes longer with the increasing carbon equivalent, but the upset length shows no consistent tendencies. (2) Due to the recrystallization in the contact area, the maximum hardness occurs some away from the contact surface. And it increases almost linearly with the increasing carbon equivalent. (3) Even a steel with 1.1 C.E. can be friction welded to make defect-free welds. (4) With the increasing carbon equivalent, the bend angle and charpy impact value decrease very rapidly in the range from 0.3 C. E., but remain nearly unchanged for C. E. higher than 0.6. (5) Heat treatment of the base metals before welding has very little influence on the mechanical properties of welds. On the other hand, normalizing of the welds improves the bend angle and charpy impact value, but its effect becomes almost negligible, when the carbon equivalents are higher than 0.6.

• Journal of Magnetics
• /
• v.16 no.1
• /
• pp.58-63
• /
• 2011

This paper presents design procedures of a transverse flux linear motor (TFLM). The minimum and maximum flux linkage was determined by the simplified equivalent magnetic circuit and estimated average magnetic flux density at the air gap region by considering the shape of applied magnetomotive force (MMF). With this information, the number of turns of each phase winding was calculated based on the amplitude of applied voltage and speed of a mover. The rated current, coil diameter, and winding area were obtained with the aid of an empirical formula for determining the required MMF. The usefulness of the proposed design method for TFLM is verified by the three-dimensional equivalent magnetic circuit network (EMCN) method and the experimental results of prototyped machine.

• Journal of Microbiology and Biotechnology
• /
• v.7 no.4
• /
• pp.267-271
• /
• 1997

We developed a dermal equivalent (DE) which was engineered using human dermal fibroblasts and a matrix of collagen gel. The in vitro construction of the DE was accomplished by casting a porcine collagen type I solution plus concentrated medium with isolated and cultured fibroblasts. These constructs were attached to culture dishes or left floating in culture medium. Contraction of attached gels results in decreased gel thickness without a change in gel diameter, and contraction of floating gels results in decreased gel thickness and diameter. After contraction, there was no increase in cell number in floating gels, but cells in attached gels began to increase after about 4 days of the lag phase in cell growth curve. At this lag phase, addition of fibroblast growth factor (FGF) at a concentration of $0.1{\mu}$/ml promoted cell proliferation in the attached collagen gels, but no effect in floating gels. These results indicate that the method of contraction had an influence on the extracellular matrix (ECM) organization, and this influenced not only cell growth but also fibroblast responsiveness to FGF. This suggests that attached collagen gel is more suitable as a dermal equivalent than the floating gel. And the final contracted area of attached gel is much larger than that of the floating gel since floating gel is contracted in all directions but attached gel is contracted only vertically.

• Computers and Concrete
• /
• v.21 no.4
• /
• pp.471-484
• /
• 2018

Refined analysis depicting mass transportation and physicochemical reaction and reasonable computing load with acceptable DOFs are the two major challenges of numerical simulation for concrete durability. Mesoscopic numerical simulation for chloride diffusion considering binder, aggregate and interfacial transition zone is unable to be expended to the full structure due to huge number of DOFs. In this paper, a multiscale approach of combining both mesoscopic model including full-graded aggregate and equivalent macroscopic model was introduced. An equivalent conversion of chloride content at the Interfacial Transition Layer (ITL) connecting both models was considered. Feasibility and relative error were discussed by analytical deduction and numerical simulation. Case study clearly showed that larger analysis model in multiscale model expanded the diffusion space of chloride ion and decreased chloride content in front of rebar. Difference for single-scale simulation and multiscale approach was observed. Finally, this paper addressed some worth-noting conclusions about the chloride distribution and rebar corrosion regarding the configuration of rebar placement, rebar diameter, concrete cover and exposure period.

• Journal of Biomedical Engineering Research
• /
• v.18 no.3
• /
• pp.253-259
• /
• 1997

Von Mises stress and compliance distribution was evaluated using a finite element analysis on the anastomosis of an artery with length of 20mm(z direction, along the horizental artery), inner diameter of 4mm, thickness fo 0.5mm and a PTFE graft with length of 5.7mm, inner diameter of 2mm, thickness of 0.2mm when anastomotic angle was $45^{\circ}$ and inner pressure of 1330 dyne/mm2 was applied inside the 2 conduits. From the analysis results were obtained as follows. (1) Artery diameter increased in both horizontal x(along the length of artery) and vertical y(perpendicular to the length of artery)directions and the magnitude of that in x direction was bigger than that in y direction. (2) The compliance was maximum on the anastomosis, especially on that with acute angle. The reduction of compliance was observed from the anastomosis area to the either right or left end. (3) The equivalent stress was maximum on top in the y direction and minimum on the nodes apart $110^{\circ}$ in circumferential direction from the top. (4) The equivalent stress was maximum in t도 vicinity of anastomosis with acute angle along the longitudinal direction of the artery. This trend was also observed along the PTFE graft.

• Transactions of the Korean Society of Mechanical Engineers B
• /
• v.23 no.8
• /
• pp.997-1009
• /
• 1999

Silica particle formation and growth process including chemical reaction, coagulation and sintering was studied in a counterflow diffusion flame burner. The counterflow geometry provides a one dimensional flow field, along the stagnation point streamline, which greatly simplifies interpretation of the particle growth characteristics. $SiCl_4$ has been used as the source of silicon in hydrogen/oxygen/argon flames. The temperature profiles obtained by calculation showed a good agreement with experiment data. Using one and two dimensional sectional method, aerosol dynamics equation in a flame was solved, and these two results were compared. The two dimensional section method can consider sintering effect and growth of primary particle during synthesis, thus it showed evolution of morphology of non-spherical particles (aggregates) using surface fractal dimension. The effects of flame temperature and chemical loading on particle dynamics were studied. Geometric mean diameter based on surface area and total number concentration followed the trend of experiment results, especially, the change of diameters showed the sintering effect in high temperature environment.