• Asian-Australasian Journal of Animal Sciences
• /
• v.33 no.4
• /
• pp.623-633
• /
• 2020

Objective: Substituting starch with digestible fiber (dF) can improve digestive health of rabbits and reduce costs. Therefore, it is necessary to develop a criterion for dF and starch supply. Effects of the dietary dF-to-starch ratio on pellet quality, growth and cecal microbiota of Angora rabbits were evaluated. Methods: Five isoenergetic and isoproteic diets with increasing dF/starch ratios (0.59, 0.66, 0.71, 1.05, and 1.44) were formulated. A total of 120 Angora rabbits with an average live weight of 2.19 kg were randomly divided into five groups with four replicates. At the end of 40 day feeding trial, cecal digesta were collected to analyse microbiota. Results: The results showed that the dF/starch ratio had linear effects on pellet variables (p<0.01). When the dF/starch ratio was 1.44, the pellets had the lowest powder and highest durability. The dF/starch ratio had unfavorable linear effects on growth variables (p<0.001). When analyzed by quadratic regression, the optimal dF/starch ratios for average weight gain and feed/gain were 0.59 and 0.74, respectively. There were differences in wool yield, fiber length and fiber diameter caused by the dF/starch ratio (p<0.05), and the dF/starch ratios that ranged from 0.66 to 1.06 were appropriate for good results. The cecal microbiota operational taxonomic unit (OTU) number index in the 1.05 dF/starch treatment was higher than that in the 0.66 and 0.71 dF/starch treatments. The higher dF/starch ratio resulted in a higher cecal microbiota OTU number index (p<0.05). The proportion of Ruminococcus in the 0.71 dF/starch treatment was higher than that in the 0.59 dF/starch treatment (p<0.05) Conclusion: The most suitable dF/starch ratio for feed pellet quality is 1.44, and for rabbit growth the optimal range of ratios is from 0.59 to 0.74. With combination of the wool growth, output cost, and cecal microbiota, we suggest that a dietary dF/starch ratio ranging from 0.74 to 1.06 is optimal.

• Advances in aircraft and spacecraft science
• /
• v.7 no.3
• /
• pp.203-214
• /
• 2020

In many applications like the aircraft or the rockets/missiles, the flow from a nozzle needs to be expanded suddenly in an enlarged duct of larger diameter. The enlarged duct is provided after the nozzle to maximize the thrust created by the flow from the nozzle. When the fluid is suddenly expanded in an enlarged duct, the base pressure is generally lower than the atmospheric pressure, which results in base drag. The objective of this research work is to optimize the length to diameter (L/D) ratio of the enlarged duct using the CFD analysis in the flow field from the supersonic nozzle. The flow from the nozzle drained in an enlarged duct, the thrust, and the base pressure are studied. The Mach numbers for the study were 1.5, 2.0 and 2.5. The nozzle pressure ratios (NPR) of the study were 2, 5 and 8. The L/D ratios of the study were 0.5, 1, 2, 3, 4, 5, 6, 7, 8, 9 and 10. Based on the results, it is concluded that the L/D ratio should be increased to an optimum value to reattach the flow to an enlarged duct and to increase the thrust. The supersonic suddenly expanded flow field is wave dominant, and the results cannot be generalized. The optimized L/D ratios for various combinations of flow and geometrical parameters are given in the conclusion section.

• Proceedings of the Korean Society for Emotion and Sensibility Conference
• /
• 2001.11a
• /
• pp.169-172
• /
• 2001

There are many people who suffer from simulation sickness when immersing in virtual reality. In this study, we analyzed two photoplethysmogram(PPG) parameters - a second derivative parameter and power spectral density ratios - in order to relate PPG parameters with simulation sickness. 36 young, healthy subjects were participated in the experiment, and each subject was equipped with a PPG electrode during his or her immersion. Simulation sickness section was defined as a 7 - second section which starts from the point where a subject reported simulation sickness, and normal section as a same-length section where no physical stimuli was presented to him or her. We compared the PPG parameters of the simulation sickness sections with the normal sections, - d/a ratio is believed to have lower value during vasodilation and higher value during vasoconstriction, however, we could not find much difference in the parameter between normal and simulation sickness sections. We also compared 1 to 10Hz power spectral density ratios in normal sections with in simulation sickness section, and found that 6 density ratios among them have different value. Therefore, the density ratios might be utilized as parameters to detect simulation sickness of subjects.

• Steel and Composite Structures
• /
• v.16 no.1
• /
• pp.97-114
• /
• 2014

This paper deals with a study on ultimate strength behaviour of eccentrically loaded CFT columns with and without shear connectors. Thirty specimens are subjected to experimental investigation under eccentric loading condition. P-M curves are generated for all the test specimens and critical eccentricities are evaluated. Three different D/t ratios such as 21, 25 and 29 and L/D ratios varying from 5 to 20 are considered as experimental parameters. Six specimens of bare steel tubes as reference specimens, twelve specimens of CFT columns without shear connectors and twelve specimens of CFT columns with shear connectors, in total thirty specimens are tested. The P-M values at the ultimate failure load of experimental study are found to be well agreed with the results of the proposed P-M interaction model. The load-deflection and load-strain behaviour of the experimental column specimens are presented. The behaviour of the CFT columns with and without shear connectors is compared. Experimental results indicate that the percentage increase in load carrying capacity of CFT columns with shear connectors compared to the ordinary CFT columns is found to be insignificant with a value ranging from 6% to 13%. However, the ductility factor of columns with shear connectors exhibit higher values than that of the CFT columns without shear connectors. This paper presents the proposed P-M interaction model and experimental results under varying parameters such as D/t and L/D ratios.

• Bulletin of the Korean Chemical Society
• /
• v.31 no.2
• /
• pp.372-378
• /
• 2010

Membrane disruption by an antimicrobial peptide, protegrin-1 (PG-1), was investigated by measuring the $^2H$ solid-state nuclear magnetic resonance (SSNMR) spectra of 1-palmitoyl-$d_{31}$-2-oleoyl-sn-glycero-3-phosphatidylcholine (POPC_$d_{31}$) in the mixture of PG-1 and POPC_$d_{31}$ lipids deposited on thin cover-glass plates. The experimental line shapes of anisotropic $^2H$ SSNMR spectra measured at various peptide-to-lipid (P/L) ratios were simulated reasonably by assuming the mosaic spread of bilayers containing pore structures or the coexistence of the mosaic spread of bilayers and a fast-tumbling isotropic phase. Within a few days of incubation in the hydration chamber, the pores were formed by the peptide in the POPC_$d_{31}$ and POPC_$d_{31}$/cholesterol membranes. However, the formation of the pores was not clear in the POPC_$d_{31}$/1-palmitoyl-2-oleoyl-sn-glycero-3-phosphatidylglycerol (POPG) membrane. Over a hundred days after hydration, a rapidly rotating isotropic phase increased in the POPC_$d_{31}$ and the POPC_$d_{31}$/cholesterol membranes with the higher P/L ratios, but no isotropic phase appeared in the POPC_$d_{31}$/POPG membrane. Cholesterol added in the POPC bilayer acted as a stabilizer of the pore structure and suppressed the formation of a fast-tumbling isotropic phase.

• Nuclear Engineering and Technology
• /
• v.45 no.6
• /
• pp.707-720
• /
• 2013

We analyze piecewise homogenization with flux-weighted cross sections and preservation of averaged currents at the boundary of the homogenized domain. Introduction of a set of flux discontinuity ratios (FDR) that preserve reference interface currents leads to preservation of averaged region reaction rates and fluxes. We consider the class of numerical discretizations with one degree of freedom per volume and per surface and prove that when the homogenization and computing meshes are equal there is a unique solution for the FDRs which exactly preserve interface currents. For diffusion submeshing we introduce a Jacobian-Free Newton-Krylov method and for all cases considered obtain an 'exact' numerical solution (eight digits for the interface currents). The homogenization is completed by extending the familiar full assembly homogenization via flux discontinuity factors to the sides of regions laying on the boundary of the piecewise homogenized domain. Finally, for the familiar nodal discretization we numerically find that the FDRs obtained with no submesh (nearly at no cost) can be effectively used for whole-core diffusion calculations with submesh. This is not the case, however, for cell-centered finite differences.

• Asia pacific journal of information systems
• /
• v.7 no.1
• /
• pp.25-48
• /
• 1997

This study examines whether expenditures in information technology (IT) are associated with increases in the Tobin's q ratios a measure of organizational performance. It uses two groups of sample, Korean and American firms that disclose IT expenditures. For the all-firms group of each country, the association between IT expenditures and Tobin's q ratios is positive and statistically significant. But the association varies among industries. For Korean firms, IT expenditures appear to increase Tobin's q ratios for the machine and equipment manufacturing industry group (SIC3-2). IT expenditure ratio of this group as a percent of total sales is highest among the industry groups. For all service industry groups(SIC4&5), the estimated coefficient of IT expenditures is positive but statistically insignificant. For American firms IT expenditures in most of the manufacturing industry groups appear to increase only a little, if at all, for the Tobin's q ratios. But IT expenditures appear to have a greater impact on Tobin's q ratios for all service industries (SIC4-7). For three service industries tested (transportation and telecommunication- SIC4, financial- SIC6, consulting and other service industry- SIC7), the estimated coefficient of IT expenditures is positive and statistically significant. The evidence from both Korean and American firms suggests that IT expenditures in service industries provide a greater impact on an organizational performance than ones in manufacturing industry. To test whether service industries use a competitive strategy utilizing IT as a core competence, the samples ore divided into two groups, service and manufacturing industry. For Korean firms, both IT and R&D expenditures in manufacturing industry are associated with increases in Tobin's q ratios. But for service industry, the estimated coefficient of only IT expenditure is positive. For American firms, the estimated coefficients of both IT and advertising and R&D (ARD) expenditures in manufacturing industry are positive but the coefficient of only ARD is statistically significant. For service industry, the estimated coefficient of only IT expenditure is positive and statistically significant. The evidence may suggest that manufacturing industry uses both R&D and IT strategies to increase a competitive advantage but uses R&D strategy as a core competence. However, service industry uses IT strategy as a core competence to increase a competitive advatage.

• Proceedings of the KIPE Conference
• /
• 2018.07a
• /
• pp.63-65
• /
• 2018

This paper presents a DTC-PWM(Direct Torque Control-Pluse Width Modulation) method of PMSM(Permanent Magnet Synchronous Motor) using the flux-torque hysteresis band. In order to keep the flux and torque error of the PMSM within the hysteresis band, the optimal PWM duty ratio is calculated by the error of the flux and torque with the flux and torque vector of the selected voltage vector. According to the flux duty ratios and the torque duty ratios, the optimized duty ratio to reduce the errors is selected by the calculated duty ratios. In the proposed method, the selected voltage vector is divided into d-q axis components with a simple method. And the flux duty ratios and torque duty ratios are estimated by the applied voltage vector. The proposed DTC-PWM for PMSM was verified by computer simulation.

• Journal of Korean Ophthalmic Optics Society
• /
• v.19 no.3
• /
• pp.345-351
• /
• 2014

Purpose: The accommodative response and the near horizontal phoria were examined with additional spherical power to analyze the stimulus and response AC/A ratios that suggest reference data for the binocular vision. Methods: The open-field autorefractometer (Nvision-K 5001, Shin nippon) and modified thorington method (MIM card; Muscle Imbalance Measure card, Bernell) at 40 cm were utilized to measure the accommodative response and the near horizontal phoria for 81 persons ($20.89{\pm}1.92$ years old) with additional spherical power. The stimulus and the response AC/A ratios were calculated by gradient AC/A method. Results: The exophoria group showed the highest accommodative response ($1.92{\pm}0.26D$) at 40 cm, followed by orthophoria group and esophoria group($1.72{\pm}0.26D$ and $1.62{\pm}0.42D$, respectively) Meanwhile, the esophoria group showed the biggest ocular deviation for the near ($23.24{\Delta}$) followed by the orthophoria group and exophoria group ($19.76{\Delta}$ and $15.14{\Delta}$, respectively). The biggest difference of the stimulus and the response AC/A ratios was $1.72{\Delta}$ for the exophoria group with -2.00 D, while the one was $3.43{\Delta}$ for the esophoria group with +1.00 D. There was a significant difference between AC/A ratios for the exophoria group with -2.00 D, -1.00 D and the esophoria group with +3.00 D, +2.00D, +1.00D and -1.00D. Conclusions: The difference between stimulus and response AC/A was greater when increased minus spherical power for the exophoria group, while it was greater when increased plus spherical power for the esophoria group. Furthermore, the difference for the esophoria group was a greater than the one for the exophoria group.

• Research in Mathematical Education
• /
• v.17 no.1
• /
• pp.63-78
• /
• 2013

Trigonometric ratios are difficult concepts to teach and learn in middle school. One of the reasons is that the mathematical terms (sine, cosine, tangent) don't convey the idea literally. This paper deals with the understanding of a concept from the learner's standpoint, and searches the orientation of teaching that make students to have full understanding of trigonometric ratios. Such full understanding contains at least five constructs as follows: skill-algorithm, property-proof, use-application, representation-metaphor, history-culture understanding [Usiskin, Z. (2012). What does it mean to understand some mathematics? In: Proceedings of ICME12, COEX, Seoul Korea; July 8-15,2012 (pp. 502-521). Seoul, Korea: ICME-12]. Despite multi-aspects of understanding, especially, the history-culture aspect is not yet a part of the mathematics class on the trigonometric ratios. In this respect this study investigated the effect of history approach on students' understanding when the history approach focused on the mathematical terms is used to teach the concept of trigonometric ratios in Grade 9 mathematics class. As results, the experimental group obtained help in more full understanding on the trigonometric ratios through such teaching than the control group. This implies that the historical derivation of mathematical terms as well as the context of mathematical concepts should be dealt in the math class for the more full understanding of some mathematical concepts.