• The Journal of the Acoustical Society of Korea
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• v.43 no.4
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• pp.455-465
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• 2024

In shallow water, the array invariant, known as the effective range estimation method, is developed based on the broadband dispersion characteristics in an ideal waveguide, which can be summarized by the waveguide invariant. It is robust enough to estimate both the array tilt and range simultaneously, even in situations where array tilt exists. Recently, it has been extended to fully consider the angle dependence of the waveguide invariant. However, applying the array invariant in range-dependent environments instead of range-independent environments can lead to range estimation errors due to bathymetry mismatch. In this paper, we interpret such range estimation errors by introducing the concept of effective range. Through numerical simulations and experimental data in a weakly range-dependent environment, we demonstrate the relationship between range estimation errors and effective range.

• Fashion & Textile Research Journal
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• v.7 no.4
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• pp.413-418
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• 2005

The purpose of this study was for the adult woman that provides the investigation, analysis, consideration of the relationship with clothing behavior and self-efficacy depends on their skin care grade. Data were collected from 477 adult females and analyzed by using frequency, dispersion analysis, ANOVA, t-test, Duncan test utilizing SPSS 10.0 program. The results were as follows: The younger and the more educated respondents were the better their skin care. Also, the more they spent on clothes, the more they spent on cosmetic products. For occupations, professionals were to have better skin care. It was expose that 20s and 30s are shown difference for all low rank leading persons except conformity in the midst of it is clothing behavior main point by skin care management degree, 40s appeared that difference is seen in interest, psychological dependence, aesthetics, management. It was expose that difference does not exist in liver that is clothing behavior main point by skin care administration degree in 50s. 20s appeared difference in general self-efficacy divination in self-efficacy, and 30s appeared that skin care degree is high as general self-efficacy and physical self-efficacy are high. It was expose that 40s and 50s are no difference of self-efficacy in between group by skin care degree.

• Elastomers and Composites
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• v.52 no.4
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• pp.257-265
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• 2017

In this work, CR (Chloroprene Rubber) was emulsified by phase-inversion emulsification with nonionic surfactants (NP-1025, LE-1017, and OP-1019) and an anionic surfactant (SDBS; sodium dodecylbenzenesulfonate), and its stabilization was investigated through a study of its adsorption characteristics, zeta potential, and flow behavior. As the amount of the mixed surfactant increased, the droplet size decreased, resulting in the increase of viscosity. In particular, a CR emulsion with a lower absorbance in the UV spectrum exhibited the highest zeta potential. The results of this experiment showed that the CR emulsion prepared using (LE-1017) and SDBS was the most stable. In this study, calcium hydroxide and aluminum hydroxide were added to enhance the mechanical properties of the CR emulsion, and the relationship between tensile strength, tear strength and surface free energy were investigated. The tensile and tear strengths of the CR emulsion incresed as the amount of calcium hydroxide and aluminum hydroxide increased. The highest tensile and tear strengths and surface free energy were observed for additions of 1.0% calcium hydroxide and 0.80% aluminum hydroxide, respectively. It was concluded that the interfacial bonding strength was improved by the even dispersion of calcium hydroxide and aluminum hydroxide in the CR emulsion.

• Journal of Korea Foundry Society
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• v.13 no.3
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• pp.248-258
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• 1993

A semi-solid alloy in which solid and liquid phase are co-existing is obtained by stirring of A17075 molten metal. A semi-solid alloy is dependent on the corresponding temperature within the solid-liquid range, and the process parameters should be controlled accurately to obtain the homogeneous semisolid alloy. The fabrication possibility of fiber-reinforced aluminum alloy containing $Al_2O_3$ short fibers with vigorous agitation of short fibers were obtained by control of stirring time, solid fraction and impeller speed in extrusion billet fabrication processes. The microstructure to extrusion billet fabricated by low pressure casting was investigated for fiber dispersion state. The relationship between the extrustion force and velocity at hot extrustion, the flow strain and extrusion ratio were theoretically described. The surface defects with lubricants and without lubricant after hot extrusion were investigated. The composites materials after hot extrusion were measured by vickers hardness with extrusion ratio. It has become clear that the secondary working such as hot extrusion was very useful to obtained improved the mechanical properties of metal matrix composites.

• Food Science and Biotechnology
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• v.14 no.2
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• pp.233-237
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• 2005

Rheological properties of acorn flour-guar gum mixtures (4% w/w) at different guar gum concentrations (0, 0.2, 0.4, 0.6, and 0.8% w/w) were evaluated in steady and dynamic shear. The acorn flour-guar gum mixtures at $25^{\circ}C$ showed high shear-thinning flow behavior (n= 0.20-0.27). Consistency index (K), apparent viscosity (${\eta}_{a,100}$), and Casson yield stress (${\sigma}_{oc}$) increased with the increase in guar gum concentration. Within the temperature range of $25-70^{\circ}C$, the {\eta}_{a,100}$ of mixtures obeyed the Arrhenius relationship with high determination coefficient ($R^2=\;0.974-0.994$). Activation energy values (5.37-6.77 kJ/mole) of acorn flour dispersions in the mixtures with guar gum (0.2-0.8%) were much lower than that (12.5 kJ/mole) of acorn flour dispersion (0% guar gum). Storage modulus (G'), loss modulus (G"), and complex viscosity (${\eta}^*$) increased with the increase in guar gum concentration. Dynamic rheological data of 1n (G', G") versus ln frequency (w) of guar gum-acorn flour mixtures had positive slopes with G' greater than G" over most of the frequency range, indicating that they exhibited weak gel-like behavior.

• Coupled systems mechanics
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• v.6 no.3
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• pp.335-349
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• 2017

To cope with the demand on giant and durable buildings, reinforcement of concrete is a practical problem being extensively investigated in the civil engineering field. Among various reinforcing techniques, fiber-reinforced concrete (FRC) has been proven to be an effective approach. In practice, such fibers include steel fibers, polyvinyl alcohol (PVA) fibers, polyacrylonitrile (PAN) carbon fibers and asbestos fibers, with the length scale ranging from centimeters to micrometers. When advancing such technique down to the nanoscale, it is noticed that carbon nanotubes (CNTs) are stronger than other fibers and can provide a better reinforcement to concrete. In the last decade, CNT-reinforced concrete attracts a lot of attentions in research. Despite high cost of CNTs at present, the growing availability of carbon materials might push the usage of CNTs into practice in the near future, making the reinforcement technique of great potential. A review of existing research works may constitute a conclusive reference and facilitate further developments. In reference to the recent experimental works, this paper reports some key evaluations on CNT-reinforced cementitious materials, covering FRC mechanism, CNT dispersion, CNT-cement structures, mechanical properties and fire safety. Emphasis is placed on the interplay between CNTs and calcium silicate hydrate (C-S-H) at the nanoscale. The relationship between the CNTs-cement structures and the mechanical enhancement, especially at a high-temperature condition, is discussed based on molecular dynamics simulations. After concluding remarks, challenges to improve the CNTs reinforcement technique are proposed.

• Journal of Korean Society for Quality Management
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• v.22 no.4
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• pp.1-12
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• 1994

For quality improvement, Taguchi emphasizes the reduction of variation of the quality characteristic. Taguchi has used the signal to noise ratios for achieving minimum dispersion of the quality characteristic with its location adjusted to some desired target value. At each setting of design factors, the variance of the quality characteristic could be affected by the mean. In most cases, as the mean get larger, the variance tends to increase, The Taguchi's SN ratio corresponds to the case that the variance is proportional to the square of the mean. But the variance can increase faster or slower than the square of the mean. We propose to infer a linking relationship of the variance and mean through simple data analysis technique, and then use a reasonable SN ratio.

• Fisheries and Aquatic Sciences
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• v.10 no.2
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• pp.86-92
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• 2007

Adult Dungeness crabs are restricted primarily in the lower part of Glacier Bay, Alaska, but the interaction of larval dispersion and adult distribution is unknown. To understand the larval occurrence in the upper part of Glacier Bay, Dungeness crab larvae, sea surface temperature (SST), and sea surface salinity (SSS) were collected at 16 near-shore and 12 mid-channel stations in Glacier Bay, southeastern Alaska during six sampling periods from March through August 2000. Each station was visited from one to five times during the entire sampling period. Geographic Information System (GIS) was used to contour SST and SSS distribution in Glacier Bay. Seven to 27 stations were visited during each sampling period. Most larvae (85% were zoeae I) occurred during May 31 to June 14, 2000. Larval density varied from none to $51.4\;100\;m^{-3}$ between stations. A few later stage larvae occurred during later sampling periods. Overall, no relationship between larval densities, and SSS, and SST existed. Larvae occurring in the upper bay were probably transported by tidal currents from the lower bay; adult Dungeness crabs in Glacier Bay have a relatively high density near the mouth of the bay but decrease sharply around 40km north of the mouth. The lack of adult crabs in the upper 60km of the bay may be related to lower salinity, resulting in sharp haloclines, or colder temperatures which are not conducive to survival or growth of either larvae or adults.

• The Journal of Asian Finance, Economics and Business
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• v.7 no.9
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• pp.39-49
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• 2020

This study empirically examines herd behavior for fast moving consumer goods (FMCG) sector stocks under varied market return conditions and the period during the global financial crisis and its aftermath. We examine the sample of stocks trading on the Nifty FMCG Index of the Indian equity market from January 2008 up to December 2018 using the dispersion measure of cross sectional absolute deviation and examine its relationship with the market return to explore herd phenomenon. Quantile regression estimate is used and the results of the study validate rational asset pricing models as the sector does not display herding. In contrast, anti-herd behavior at lower and median quantile values is observed. A possible reason can be the non-cyclical nature of the industry where investors rely more on the fundamentals rather than crowd chasing. We also findthe absence of herd phenomenon during the market asymmetries of bull and bear phases, extreme movements, the period of the global financial crisis, and afterward. We further examine herding under the impact of the information technology (IT) industry and conclude that significant return movements in IT sector impact dispersions in the FMCG industry. Also, there is a co-varying risk between the two sectors confirming the spillover in an integrated market.

• Asian-Australasian Journal of Animal Sciences
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• v.5 no.1
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• pp.183-188
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• 1992

Behaviour of 7 horned Japanese Black Cattle (3-9 years old) kept in a $450m^2$ dry-lot under loose housing condition was observed in the daytime (0930-1730 h) during 3 consecutive days. Eating and lying behaviour of cattle and the positions of all animals when lying together were recorded at 10-min intervals. Agonistic encounters and social licking interactions in the herd were also recorded. The cattle established a social hierarchy which was near linear. An irregularity in the diurnal rhythm of lying behaviour was found on the 3rd day, which appeared to be caused by oestrus behaviour of a herdmate. Eating frequency showed greater variation among individuals than lying frequency, and the most dominant animal ate most frequently in the herd. The spatial pattern of the herd when lying indicated a relatively loose dispersion in the lot. Higher ranking cattle tended to lie down more frequently near the hay rack in the lot, so that lower ranking animals had more difficult access to feed. Cattle with more social licking interactions had a tendency to lie down near each other irrespective of proximity of social order, therefore it was suggested that social preference among particular individuals occurred in the herd.