• Food Engineering Progress
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• v.15 no.3
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• pp.221-229
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• 2011

Optimization study of the hot water extraction for enhancing antioxidative activity from Auricularia auricula was performed by Taguchi approach using orthogonal matrix $L_9(3^4)$ method. The correlation between DPPH radical scavenging activity and the components of samples extracted from different extraction conditions were also analyzed. The correlation coefficient between DPPH radical scavenging activity and melanin content of A. auricula were 0.93, indicating 'good correlation'. The optimum extraction conditions was obtained at the extraction time of 1 hr. temperature of $85^{\circ}C$, solid: water ratio of 1: 40(w/v) and frequency of 2 times. Under these conditions, values of maximum DPPH free radical scavenging activity and melanin contents of A. auricula were $67.21{\pm}2.17$ and $52.94{\pm}2.10 mg/g$, respectively. Melanin content of 1.6 times and DPPH free radical scavenging effect of 130% were enhanced by optimization.

• KIEE International Transactions on Electrophysics and Applications
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• v.5C no.6
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• pp.251-256
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• 2005

Directionally melt-textured high $T_c\;(Y_{0.5}Nd_{0.25}Sm_{0.25})Ba_{2}Cu_{3}O_y$ [(YNS)-123] superconductor was systematically investigated by the zone melt growth process in air. A sample prepared by this method showed well-textured microstructure, and $(Y_{0.5}Nd_{0.25}Sm_{0.25})_{2}BaCuO_5$[(YNS)211] inclusions were uniformly dispersed in large $(Y_{0.5}Nd_{0.25}Sm_{0.25})Ba_{2}Cu_{3}O_y$ [(YNS)123] matrix. High irreversibility field and magnetization hysteresis loop of the zone melt-textured (YNS)-123 sample exhibited the enhanced flux pinning, compared with $YBa_{2}Cu_{3}O_y$ (Y-123) sample without RE(rare earth). Critical current density of (YNS)-123 sample was $2.5{\times}10^4\;A/cm^2$ at 2 T and 77 K.

• Bulletin of the Korean Mathematical Society
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• v.51 no.2
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• pp.595-612
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• 2014

The spectral collocation method for a second order elliptic boundary value problem on a domain ${\Omega}$ with curved boundaries is studied using the Gordon and Hall transformation which enables us to have a transformed elliptic problem and a square domain S = [0, h] ${\times}$ [0, h], h > 0. The preconditioned system of the spectral collocation approximation based on Legendre-Gauss-Lobatto points by the matrix based on piecewise bilinear finite element discretizations is shown to have the high order accuracy of convergence and the efficiency of the finite element preconditioner.

• Journal of Magnetics
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• v.11 no.3
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• pp.139-142
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• 2006

We fabricated new one-dimensional magnetophotonic crystal (1D-MPC) utilizing the second and third photonic band gaps where localized modes existed. Structure of the 1D-MPC was $(Ta_{2}O_{5}/SiO_{2})_{5}/Bi:YIG/(SiO_{2}/Ta_{2}O_{5})_{5}$ with optical thicknesses of 3$\lambda$ /4 for $Ta_{2}O_{5} and $SiO_2$ dielectric layers and $\lambda$ /2 for Bi:YIG defect layer, where $\lambda$ is a wavelength of a localized mode in the second photonic band gap. Faraday rotation at the localized mode in the second photonic band gap was enhanced, which was confirmed by calculation using 4${\times}$4 matrix method.

• Journal of Radiation Protection and Research
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• v.11 no.2
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• pp.91-103
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• 1986

Experimental study for the leaching behavior of Cs-137 was carried out using the simulated evaporator bottom product of PWR plant. The method of leach test proposed by the IAEA was partially modified using ANS method. The effect of various factors, i.e., sampling method, curing temperature, curing time, leachant temperature, vermiculite addition and volume-to-surface ratio, was considered in this experiment. Diffusion model in semi-infinite slab was in a good agreement with the data obtained from 4-weeks cured specimens. The effective diffusion coefficient of the specimens which were cured at the temperature of $24^{\circ}C$ for 4 weeks was found to be $1.20{\sim}1.47{\times}10^{-11}cm^2/sec$. With the experimentally obtained diffusion coefficient ($1.47{\times}10^{-11}cm^2/sec$), long-term prediction for the leaching of Cs-137 was carried out using finite-slab approximation. The estimated fraction of Cs-137 which remains in the environment is found to be less than 0.25 percent of initial amount after 100 years. About 25 years after the beginning of leaching, its fractional amount in the environment reachs the maximum value, 0.66 percent of initial amount.

• Korean Journal of Construction Engineering and Management
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• v.23 no.5
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• pp.77-86
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• 2022

Safety accidents on the construction scene can cause serious accidents, that take worker's life, and as the government has been making great efforts to reduce industrial accidents, the role of safety managers closely related to accidents at construction sites is becoming important. However, job stress is high due to excessive workload and inefficient work managed by safety managers in the current construction safety management system. So, it is necessary to improve and simplify the work contents. The main purpose of this study is to identify and improve tasks that need improvement and simplification of inefficient tasks, obtained through expert opinions and surveys on the level of difficulty and prevention effect of tasks in the safety manager's working stage, by using 2×2 Matrix analysis techniques. Therefore, this study will ultimately contributes reducing the occurrence of safety accidents on the construction scene.

• Transactions on Electrical and Electronic Materials
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• v.6 no.6
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• pp.284-288
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• 2005

We have systematically studied the superconducting properties and flux pinning enhancement of $(Y_{0.33}Sm_{0.33}Nd_{0.33})\;Ba_2Cu_3O_y$ [(YSN)-123] composite oxides by melt growth process in air. A sample prepared by this method showed well-textured microstructure, and $(Y_{0.33}Sm_{0.33}Nd_{0.33})\;BaCuO_5$ [(YSN)211] nonsuperconducting particles were uniformly dispersed in large (YSN) 123 superconducting matrix. The sample showed a sharp superconducting transition at 91 K. The magnetization measurements of the (YSN)-123 sample exhibited the enhanced flux pinning, compared with $YBa_2Cu_3O_y$ (Y-123) sample without Sm and Nd. Critical current densities of (YSN)-123 sample was $2.5{\times}10^4 A/cm^2$ at 2 T and 77 K.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.24 no.4
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• pp.501-507
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• 2020

This paper proposes a new frame synchronization technique based on convolutional neural network (CNN). The conventional frame synchronizers usually find the matching instance through correlation between the received signal and the preamble. The proposed method converts the 1-dimensional correlator ouput into a 2-dimensional matrix. The 2-dimensional matrix is input to a convolutional neural network, and the convolutional neural network finds the frame arrival time. Specifically, in additive white gaussian noise (AWGN) environments, the received signals are generated with random arrival times and they are used for training data of the CNN. Through computer simulation, the false detection probabilities in various signal-to-noise ratios are investigated and compared between the proposed CNN-based technique and the conventional one. According to the results, the proposed technique shows 2dB better performance than the conventional method.

• International Journal of Reliability and Applications
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• v.18 no.2
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• pp.21-44
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• 2017

Accelerated life tests (ALTs) are frequently used in manufacturing industries to evaluate the reliability of products within a reasonable amount of time and cost. Test units are subjected to elevated stresses which yield quick failures. Most of the previous works on designing ALT plans are focused on tests that involve a single stress. Many times more than one stress factor influence the product's functioning. This paper deals with the design of optimum modified ramp-stress ALT plan for Burr type XII distribution with Type-I censoring under two stress factors, viz., voltage and switching rate each at two levels- low and high. It is assumed that usage time to failure is power law function of switching rate, and voltage increases linearly with time according to modified ramp-stress scheme. The cumulative exposure model is used to incorporate the effect of changing stresses. The optimum plan is devised using D-optimality criterion wherein the ${\log}_{10}$ of the determinant of Fisher information matrix is maximized. The method developed has been explained using a numerical example and sensitivity carried out.

• Journal of the Korea Institute of Military Science and Technology
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• v.7 no.1
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• pp.47-58
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• 2004

Loss factors of A356, Mn-Cu alloy and aluminum matrix composites reinforced with $SiC_p$ and Ni-coated graphite particles at various contents have been investigated using clamped-free cantilever beam method. The loss factors of half-power bandwidth of the specimens were measured over a wide range of frequencies from 50 to 3300Hz. Among the specimens, Al-10%$SiC_p$-10%$C_p$ showed the highest loss factor at the mode I, while Mn-Cu alloy showed the highest loss factors at the modes II and III. Consequently, at the mode I the Al-10%$SiC_p$--10%$C_p$ showed the loss factor of 0.00093, which is 2.64 and 1.58 times higher than those of A356 and Mn-Cu alloy, respectively.