• Journal of the Korean Ceramic Society
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• v.28 no.2
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• pp.119-129
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• 1991

$\gamma$-FeOOH suitable for magnetic recording media was synthesized using waste acid which is the by-product of the iron works factory. Effects of concentration of the acid and alkali and reaction temperature on the particle properties of $\gamma$-FeOOH and magnetic properties of $\gamma$-$Fe_2O_3$ were studied. $\gamma$-FeOOH single phase was formed below 1M of acid concentration with 1M of alkali concentration and at 0.4M of acid concentration with 4M of alkali concentration. While the width of acicular particle was increased, the length of acicular particle was decreased with diluting acid concentration. The magnetic properties of the $\gamma$-$Fe_2O_3$ improved with increasing acid concentration. $\gamma$-FeOOH single phase was formed in the temperature range of 30 to $80^{\circ}C$. The length of the particle was decreased with increasing temperature. $\gamma$-Fe2O3 produced from dehydration of $\gamma$-FeOOH showed bad magnetic properties due to the presence of many pores in the particle. But with successive reduction and oxidation of $\gamma$-$Fe_2O_3$ produced from dehydration of $\gamma$-FeOOH, $\gamma$-$Fe_2O_3$ showed good magnetic properties.

• Food Science and Biotechnology
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• v.14 no.5
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• pp.704-708
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• 2005

Poly-y-glutamate (${\gamma}$-PGA) has great potential as a biodegradable polymer in a broad range of industrial fields such as food, cosmetics, medicine and water treatment. In order to isolate ${\gamma}$-PGA producers that are suitable for specific industrial applications, 653 Bacillus-like strains were isolated from 439 varieties of three Korean fermented foods, Cheongkukjang, Doenjang, and Kochujang, which were collected from different regions across Korea. A very high level of ${\gamma}$-PGA production was demonstrated in 4.7%, 1.8%, and 3.0% of the Bacillus-like strains isolated from Cheongkukjang, Doenjang, and Kochujang samples, respectively, which produced a viscous substance to such extent that it overflowed to the lid of the plate on the glutamate-dependent ${\gamma}$-PGA production plates. On glutamate-independent ${\gamma}$-PGA production plates, 5.1%, 5.9%, and 6.1% of Bacillus-like strains isolated from Cheongkukjang, Doenjang, and Kochujang samples, respectively, showed high production. The maximum ${\gamma}$-PGA production yields were 32.5 g/L and 5 g/L, depending on the purification methods in the glutamate-dependent media, with the higher yield resulting from a simple precipitation of ${\gamma}$-PGA by either methanol or ethanol and dialysis. The viscous substance produced by each strain showed different morphological characteristics, suggesting that isolated ${\gamma}$-PGA producers could produce various types of ${\gamma}$-PGA.

• Communications of the Korean Mathematical Society
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• v.24 no.3
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• pp.341-351
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• 2009

The notion of rough sets was introduced by Z. Pawlak in the year 1982. The notion of a $\Gamma$-semigroup was introduced by M. K. Sen in the year 1981. In 2003, Y. B. Jun studied the roughness of sub$\Gamma$-semigroups, ideals and bi-ideals in i-semigroups. In this paper, we study rough prime ideals and rough fuzzy prime ideals in $\Gamma$-semigroups.

• Communications of the Korean Mathematical Society
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• v.23 no.4
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• pp.469-477
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• 2008

We introduce the notion of two-sided $\Gamma$-$\alpha$-derivation of a $\Gamma$-near-ring and give some generalizations of [1, 2].

• Bulletin of the Korean Mathematical Society
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• v.44 no.2
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• pp.337-350
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• 2007

Given a collection of complex numbers ${\gamma}{\equiv}\{{\gamma}ij\}$ $(0{\leq}i+j{\leq}2n,\;|i-j|{\leq}n)$ with ${\gamma}00>0\;and\;{\gamma}ji=\bar{\gamma}ij$, we consider the moment problem for ${\gamma}$ in the case of n=2, which is referred to Embry quartic moment problem. In this note we give a partial solution for the nonsingular case of Embry quartic moment problem.

• Bulletin of the Korean Mathematical Society
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• v.49 no.5
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• pp.1057-1065
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• 2012

We prove that if $\widehat{\Gamma}$ is a co-contraction of ${\Gamma}$, then the right-angled Coxeter group $C(\widehat{\Gamma})$ embeds into $C({\Gamma})$. Further, we provide a graph ${\Gamma}$ without an induced long cycle while $C({\Gamma})$ does not contain a hyperbolic surface group.

• Korean Journal of Mathematics
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• v.5 no.2
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• pp.113-118
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• 1997

According to the Bernoulli-Euler theory of elastic rods the bending energy of the wire is proportional to the total squared curvature of ${\gamma}$, which we will denote by $F({\gamma})=\int_{\gamma}k^2ds$. If the result of J.Langer and D.Singer [3] extend to knotted elastic curve, then we obtain the following. Let {${\gamma},M$} be a closed knotted elastic curve. If the curvature of ${\gamma}$ is nonzero for everywhere, then ${\gamma}$ lies on torus.

• East Asian mathematical journal
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• v.18 no.1
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• pp.75-84
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• 2002

The third important Euler-Mascheroni constant $\gamma$, like $\pi$ and e, is involved in representations, evaluations, and purely relationships among other mathematical constants and functions, in various ways. The main object of this note is to summarize some known series representaions for $\gamma$ with comments for their proofs, and to point out that one of those series representaions for $\gamma$ seems to be incorrectly recorded. A brief historical comment for $\gamma$ is also provided.

• Advances in materials Research
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• v.2 no.2
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• pp.93-98
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• 2013

Objective of this study is to calculate gamma buildup factors for pointed and isotropic gamma sources in depleted uranium, uranium dioxide, natural uranium, tin, water and concrete using MCNP4C code. The thickness of the media ranges from 0.5 to 10 mean-free-path (mfp) and gamma energy ranges from 0.5 to 10 MeV. Owing to the outstanding accuracy of MCNP in calculation involving gamma interaction, results fairly match those reported previously. The maximum relative error is 2%.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.63 no.9
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• pp.1253-1258
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• 2014

In this paper, we propose the fast and efficient detection method using the continuous measurement technique for the gamma-ray signal acquisition. This method is improved than the conventional method for the getting information of the radiation distribution. First, we implement the stereo radiation detection system using gamma-ray sensors and the motion controller. We apply continuous measurement technique to the gamma-ray detector and conduct gamma-ray irradiation test for the comparison of detection techniques. The results show that the continuous measurement technique has the high efficient performance than the conventional method.