• Transactions of Materials Processing
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• v.31 no.5
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• pp.281-289
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• 2022

Presently, 3D printers manufactured by material extrusion are economical and easy to use, so they are being used in various fields. However, this study conducted a tensile test on the infill pattern and density of the PLA+ material, due to the limitations of long printing time as well as low mechanical strength. The infill area for the infill density change was measured, using a vision-measuring machine for four infill patterns (concentric, zigzag, honeycomb, and cross) in which the nozzle path was the same for each layer. The tensile strength/weight[MPa/g] and tensile strength/printing time[MPa/min] of the tensile specimens were analyzed. In this study, efficient infill density and patterns are suggested, for cost reduction and productivity improvement. Consequently, it was confirmed that the infill area and infill percentage of the four patterns, were not constant according to the infill pattern. And the tensile strength of the infill density 40% of the honeycomb pattern and infill density 20% of the cross pattern, tended to highly consider the weight and printing time. Honeycomb and cross patterns could reduce the weight of the tensile specimen by 19.11%, 28.07%, as well as the printing time by 29.56%, 52.25%. Tensile strength was high in the order of concentric, zigzag, honeycomb, and cross patterns, considering the weight and printing time.

• The Bulletin of The Korean Astronomical Society
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• v.46 no.1
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• pp.47.2-47.2
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• 2021

Focusing on both small separations and baryonic acoustic oscillation scales, the cosmic evolution of the clustering properties of peak, void, wall, and filament-type critical points is measured using two-point correlation functions in ΛCDM dark matter simulations as a function of their relative rarity. A qualitative comparison to the corresponding theory for Gaussian random fields allows us to understand the following observed features: (i) the appearance of an exclusion zone at small separation, whose size depends both on rarity and signature (i.e. the number of negative eigenvalues) of the critical points involved; (ii) the amplification of the baryonic acoustic oscillation bump with rarity and its reversal for cross-correlations involving negatively biased critical points; (iii) the orientation-dependent small-separation divergence of the cross-correlations of peaks and filaments (respectively voids and walls) that reflects the relative loci of such points in the filament's (respectively wall's) eigenframe. The (cross-) correlations involving the most non-linear critical points (peaks, voids) display significant variation with redshift, while those involving less non-linear critical points seem mostly insensitive to redshift evolution, which should prove advantageous to model. The ratios of distances to the maxima of the peak-to-wall and peak-to-void over that of the peak-to-filament cross-correlation are ~2-√~2 and ~3-√~3WJ, respectively, which could be interpreted as the cosmic crystal being on average close to a cubic lattice. The insensitivity to redshift evolution suggests that the absolute and relative clustering of critical points could become a topologically robust alternative to standard clustering techniques when analysing upcoming surveys such as Euclid or Large Synoptic Survey Telescope (LSST).

• Asian-Australasian Journal of Animal Sciences
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• v.12 no.8
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• pp.1171-1176
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• 1999

The precision and reliability of the Computer Image Analysis technique using a desk top computer for extracting information from carcass cross section scans was evaluated by the repeatability (R) and coefficient of variation (CV) for error variance. The 6th and 7th ribs cross section of carcasses from 55 fattened Japanese Black steers were used. The image analysis was conducted using a desk top computer (Macintosh-Apple Vision 1710 Display) connected to a scanner and an image capture camera. Two software applications, Adobe Photoshop and Mac Scope were used interchangeably. The information extracted and measured were individual muscle area, circumference length, long and short axes lengths, muscle direction; distance between any two muscle centers of gravity; cross section total area, lean, fat, and bone. The information was extracted after the processes of scanning, digitization, masking, muscle separation, and binarization. When using the Computer Image Analysis technique by desk top computer, proper digitization and selection of scanning resolution are very important in order to obtain accurate information. The R-values for muscle area, circumference, long and axes lengths, and direction ranged from 0.95 to 0.99, whereas those of the distance between any two muscle centers of gravity ranged from 0.96 to 0.99, respectively. For the cross section total area, lean, fat, and bone it ranged from 0.83 to 0.99. Excellent repeatability measurements were observed for muscle direction and distance between any two muscle centers of gravity. The results indicate that the Computer Image Analysis technique using a desk top computer for extracting information from carcass cross section is reliable and has high precision.

• Fashion & Textile Research Journal
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• v.14 no.4
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• pp.677-683
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• 2012

1-octanethiol and vinyl acetate telomers ($R_8S$-nVAc) were synthesized and hydrolyzed with sodium hydroxide subsequently, 1.2-epoxyhexane was then introduced to the telomers. In addition, we prepared cotelomers of multi-alkylated nonionic surfactants with a molecular structure of xRnMA-yVA (x; hydrophobic group, y; hydrophilic group, MA; methacrylic ester, VA; vinyl alcohol, R; and alkyl group) and cross-linked with sodium tetraborate decahydrate. Their active surface properties were investigated by several techniques such as surface tension, foaming property, and emulsification power measurements. The surface tension of $R_8S$-8.8VA decreased without the introduction of 1.2-Epoxy hexane, and the degree of emulsification and foaming abilities of $R_8S$-8.8VA increased without the introduction of 1.2-Epoxy hexane. However, the differences were insignificant. The epoxy groups were attached to a $R_8S$-8.8VA cotelomer with a limited variation of the active surface properties. The surface tension of $1.1R_6MA$-8.8VA decreased after cross-linking subsequently, the degree of emulsification and foaming abilities of $1.1R_6MA$-8.8VA increased after cross-linking. However, there was no clear difference between them. The B-O bonds were attached to a $1.1R_6MA$-8.8VA cotelomer with a limited variation of the active surface properties.

• The Journal of the Acoustical Society of Korea
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• v.19 no.7
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• pp.34-41
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• 2000

This paper proposes a new double-talk detection algorithm which is based on the fuzzy rules, in the adaptive echo canceller of telecommunication system. In this method, the two inputs of the fuzzy inference for detecting double-talk condition are used. One is the cross-correlation coefficient between the error signal and the primary signal which is the summation of the real echo signal and the near-end signal. The other one is the cross-correlation coefficient between the estimation error signal and the primary signal. The fuzzy controller makes a fuzzification for two inputs by the membership functions of trapezoid does the max-min composition using if-then rules. The composed result is defuzzificated by the center gravity method. And by defuzzificated values, the double-talt the echo path variance, and the echo path variance during the double-talk are detected. It is confirmed by computer simulation that this fuzzy double-talk detector is able to estimate the double talk and the echo path variation condition, and even track echo path variation more accurately than the conventional algorithm during the double-talk period.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.14 no.10
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• pp.4706-4712
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• 2013

One of the efficient procedures for the solution of partial differential equations is the method of differential quadrature. This method has been applied to a large number of cases to circumvent the difficulties of programming complex algorithms for the computer, as well as excessive use of storage due to conditions of complex geometry and loading. Under in-plane uniform distributed load, the buckling of asymmetric curved beam with varying cross section is analyzed by using differential quadrature method (DQM). Critical load due to diverse cross section variation and opening angle is calculated. Analysis result of DQM is compared with the result of exact analytic solution. As DQM is used with small grid points, exact analysis result is shown. New result according to diverse cross section variation is also suggested.

• Particle and aerosol research
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• v.12 no.1
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• pp.21-26
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• 2016

In order to realize In-line and convenient measurement for solid-gas two phase flows, Light Transmission Fluctuation (LTF) based on the random variation of transmitted light intensity, light scattering theory and cross-correlation method was presented for online measurement of particle size, concentration and velocity. The statistical relationship among transmitted light intensity, particle size and particle number in measurement zone was described by Beer-Lambert Law. Accordingly, the particle size and concentration were determined from the fluctuation signal of transmitted light intensity. Simultaneously, the particle velocity was calculated by cross-correlation analysis of two neighboring light beams. By considering the influence of concentration variation in industrial applications, the improved algorithm based on spectral analysis of transmitted light intensity was proposed to improve measurement accuracy and stability. Therefore, the online measurement system based on LTF was developed and applied to measure pulverized coal in power station and raw material in cement plant. The particle size, concentration and velocity of powder were monitored in real-time. It can provide important references for optimal control, energy saving and emission reduction of energy-intensive industries.

• Geophysics and Geophysical Exploration
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• v.16 no.3
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• pp.163-170
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• 2013

The amplitude variation with offset of seismic data can detect fluids in the sediment and resolve the petrophysical properties of hydrocarbons in the subsurface. We analyzed and described the amplitude variation in deep sea seismic data obtained from the Ulleung Basin, East Sea. By inspecting seismic CDP-offset and CDP-angle gathers which show a bright reflection event, we decided a target zone for amplitude variation analysis. From the seismic angle gather at the middle of Ulleung Basin, we recognized amplitude increase or decrease versus offset on the intercept-gradient curve. Using the product attribute and Poisson's ratio change attribute computed in terms of intercept with gradient, the top and the base of gas saturated sediments were described. The area of amplitude variation suggestive of the presence of gas saturated sediments is shown at the depth of 3 s traveltime. Anomalous features of seismic amplitude in the Ulleung Basin were classified by the crossplot of intercept and gradient. The background trend of crossplot between intercept and gradient shows an inverse proportional relation that is common for wet sediments. Anomalous amplitudes of Class III fall into the first and the third quadrants on crossplots. We inferred regional gas/water saturated area with the horizontal dimension of 150 m in the Ulleung Basin by cross-section with respect to cross-plot anomaly.

• Journal of Korea Water Resources Association
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• v.42 no.10
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• pp.867-876
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• 2009

In this study, the stage-discharge relation curve made in 2006 is selected with standard curves to seize the hydraulic and geometric characteristics for the temporal variation of the river bed. The relationships among the standard stage-discharge relation curve and the existing stage-discharge relation curves, water level, cross sectional area, and flow velocity are analyzed. Jeokpogyo and Jindong which are the key station of Nakdong river are chosen for the study, with respect to the current river bed to convert the existing stage-discharge curves. The relationships for conversion of previous data, between water level and flow velocity are got. Also the relation equation between water level and cross sectional area and water level, flow velocity are derived. These conversion relationships shows good agreement between observed values and estimated values. It will be very useful to convert past hydraulic quantitations to current one.

• The Korean Journal of Financial Management
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• v.22 no.2
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• pp.43-69
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• 2005

This study provides empirical evidence that the stochastic beta model based on Bayesian analysis outperforms the existing conditional beta model and GARCH model in terms of the estimation accuracy and the explanatory power in the cross-section of stock returns in Korea. Betas estimated by the stochastic beta model explain $30{\sim}50%$ of the cross-sectional variation in stock-returns, whereas other time-varying beta models account for less than 3%. Such a difference in explanatory power across models turns out to come from the fact that the stochastic beta model absorbs the variation due to the market anomalies such as size, BE/ME, and idiosyncratic volatility. These results support the rational asset pricing model in that market anomalies are closely related to the variation of expected returns generated by time-varying betas.