• 호남수학학술지
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• 제30권4호
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• pp.617-629
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• 2008

In this paper, the authors have found an equivalent condition of the endomorphism ring End(M) of a projective module M being von Neumann regular(Theorem 1.14) and found an equivalent condition of any associative ring R being von Neumann regular (Theorem 1.13).

• Korean Journal of Mathematics
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• 제17권3호
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• pp.245-248
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• 2009

We consider pm-ring with the property such that every prime ideal is contained in only one maximal ideal. Orsatti[4] characterized pm-rings by means of the retraction. Contessa[1] found algebraic condition, by using that direct product of pm-rings is a pm-ring. We show that C(X, H) and C(X, C) are pm-rings and we extend a quasi pm-domain.

• 약학회지
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• 제21권1호
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• pp.27-29
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• 1977

Amoxicillin formed blue color when heated with phophomolybdic acid in adequate condition, and the color showed maximal absorbance at 760nm. Effect of pH, concentration of phosphomolybdic acid and reating time were studied. And a new colorimetric method of determination of amoxicillin was developed.

• 대한수학회보
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• 제43권4호
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• pp.805-812
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• 2006

In this paper we find a suitable bound for the number of commutators which is required to express every element of the derived group of a solvable group satisfying the maximal condition for normal subgroups. The precise formulas for expressing every element of the derived group to the minimal number of commutators are given.

• 펄프종이기술
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• 제37권1호
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• pp.25-37
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• 2005

This study was carried out to examine the optimal cultural condition in enzyme activities of CMCase, FPase and xylanase in selected strains which secret extracellular enzymes for using deinking agent to old newsprint. The results of this study were as follow: The production of enzyme by Bacillus pumilus I was maximal as grown on the medium, containing of rice bran+xylan $2.0\%$, peptone $0.8\%,\;K_2HPO_4\;0.1\%\;and\;CaCl_2\;0.06\%$ at pH 8.0 and $28^{\circ}C$ for 72 hours. Optimal cultural condition of B. subtilis I was avicel+xylan $3.5\%,\;urea\;0.4\%,\;K_3PO_4\;0.1\%\;and\;CaCl_2\;0.015\%$ at pH 9.0 and $28^{\circ}C$ for 36 hours. The maximal enzyme production was observed in the medium, containing of avicel+xylan $3.5\%,\;urea\;1.6\%\;and\; K_2HPO_4\;0.125\%$ with pH 9.0 when B. pumilus II was cultured at $28^{\circ}C$ for 60 hours. The production of enzyme by B. subtilis IT was maximal as grown on the medium, containing of xylan $2.0\%,\;yeast\; extract\;0.6\%,\;K_2HPO_4\;0.1\%\;and\;ZnSO_4\;0.04\%$ at pH 8.0 and $34^{\circ}C$ for 36 hours. The activities of FPase and xylanase in tested 4 strains were not much different with Thermomonospora fusca.

• 대한수학회보
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• 제36권2호
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• pp.225-231
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• 1999

Let Mf(x) be the Hardy-Littlewood maximal function on $\mathbb{R}^n$. Let $\Phi$ and $\Psi$ be functions satisfying $\Phi$(t) = ${\int^t}_0$a(s)ds and $\Psi(t)$ = ${\int^t}_0$b(s)ds, where a(s) and b(s) are positive continuous such that ${\int^\infty}_0\frac{a(s)}{s}ds$ = $\infty$ and b(s) is quasi-increasing. We show that if there exists a constant $c_1$ so that ${\int^s}_0\frac{a(t)}{t}dt\;c_1b(c_1s)$ for all $s\geq0$, then there exists a constant $c_1$ such that(0.1) $\int_{\mathbb{R^{n}}$ $\Phi(Mf(x))dx\;\leq\;c_2$ $\int_\mathbb{R^{n}}$$\Psi(c_2\midf(x)\mid)dx$ for all $f\epsilonL^1(R^n_$. Conversely, if there exists a constant $c_2$ satisfying the condition (0.1), then there exists a constant $c_1$ so that ${\int^s}_\delta\frac{a(t)}{t}dt=;\leq\;c_1b(c_1s$ for all $\delta$ > 0 and $s\geq\delta$.

• Safety and Health at Work
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• 제9권4호
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• pp.468-472
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• 2018

Background: Firefighters are required to use self-contained breathing apparatus (SCBA), which impairs ventilatory mechanics. We hypothesized that firefighters have elevated arterial $CO_2$ when using SCBA. Methods: Firefighters and controls performed a maximal exercise test on a cycle ergometer and two graded exercise tests (GXTs) at 25%, 50%, and 70% of their maximal aerobic power, once with a SCBA facemask and once with protective clothing and full SCBA. Results: Respiratory rate increased more in controls than firefighters. Heart rate increased as a function of oxygen consumption ($V_{O_2}$) more in controls than firefighters. End-tidal $CO_2$ ($ETCO_2$) during the GXTs was not affected by work rate in either group for either condition but was higher in firefighters at all work rates in both GXTs. SCBA increased $ETCO_2$ in controls but not firefighters. Conclusions: The present study showed that when compared to controls, firefighters' hypoventilate during a maximal test and GXT. The hypoventilation resulted in increased $ETCO_2$, and presumably increased arterial $CO_2$, during exertion. It is proposed that firefighters have altered $CO_2$ sensitivity due to voluntary hypoventilation during training and work. Confirmation of low $CO_2$ sensitivity and the consequence of this on performance and long-term health remain to be determined.

• 대한수학회논문집
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• 제10권3호
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• pp.499-518
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• 1995

In this paper we consider more systematically the centralizer C(S) of the set $S = {f_a $\mid$ f_a : X \to X ; x \longmapsto x * a, a \in X}$ with respect to the semigroup End(X) of all endomorphisms of an implicative BCK-algebra X with the condition (S). We obtain a series of interesting results. The main results are stated as follows : (1) C(S) with repect to a binary operation * defined in a certain way forms a bounded implicative BCK-algebra with the condition (S). (2) X can be imbedded in C(S) such that X is an ideal of C(S)/ (3) If X is not bounded, it can be imbedded in a bounded subalgebra T of C(S) such that X is a maximal ideal of T. (4) If $X (\neq {0})$ is semisimple, C(S) is BCK-isomorphic to $\prod_{i \in I}{A_i}$ in which ${A_i}_{i \in I}$ is simple ideal family of X.

• KSBB Journal
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• 제13권3호
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• pp.303-307
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• 1998

The fermentation conditions for the maximal production of the useful polysaccharides(water soluble polysaccharide and cell bound polysaccharide) from marine bacterium Zoogloea sp.(KCCM 10036) were investigated with a 5 L jar fermentor. The maximal production of these polysaccharides was obtained under the conditions of initial pH 7.8, 30$^{\circ}C$, 400 rpm of agitation speed, 2 Wm of aeration rate, 10%(w/v) of inoculum size and 2.5%(w/v) of glucose substrate and 10.38 g/L of total polysaccharide was produced. Apparent viscosity of the culture broth was increased with the production of these polysaccharides and the maximum value was reached to 22,500 cp.

• Journal of Communications and Networks
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• 제10권2호
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• pp.127-136
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• 2008

For mobile wireless systems with full frequency reuse, co-channel interference near the cell coverage boundaries has a significant impact on the signal reception performance. This paper addresses an approach to efficiently mitigate the effect of downlink co-channel interference when multi-antenna terminals are used in cellular environments, by proposing a signal detection strategy combined with a system-level coordination for dynamic frequency reuse. We demonstrate the utilization of multi-antennas to perform spatial demultiplexing of both the desired signal and interfering signals from adjacent cells results in significant improvement of spectral efficiency compared to the maximal ratio combining (MRC) performance, especially when an appropriate frequency reuse based on the traffic loading condition is coordinated among cells. Both analytic expressions for the capacity and experimental results using the adaptive modulation and coding (AMC) are used to confirm the performance gain. The robustness of the proposed scheme against varying operational conditions such as the channel estimation error and shadowing effects are also verified by simulation results.