• Bulletin of the Korean Chemical Society
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• v.33 no.8
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• pp.2748-2752
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• 2012

Cr(III) and Co(III) complexes with acetylacetonate were anchored onto a mesoporous MCM-41 through Schiff condensation. The materials were characterized by XRD, FT-IR, BET, CHN and ICP techniques. Elemental analysis of samples revealed that one C=N bond was formed through Schiff condensation on MCM-41 surface. The catalysts were tested for the alcohol oxidations using t-butyl hydroperoxide (TBHP) and $H_2O_2$ as oxidant. The catalytic experiments were carried out at both room temperature and reflux condition. Various solvents such as dichloromethane, acetonitrile and water were examined in the oxidation of alcohols. Among the different solvents, catalytic activity is found more in acetonitrile. Further, the catalysts were recycled three times in the oxidation of alcohols and no major change in the conversion and selectivity is observed, which shows that the immobilized metal-acetylacetonate complexes are stable under the present reaction conditions.

• Journal of the Korean Mathematical Society
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• v.51 no.1
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• pp.189-202
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• 2014

An element r of a commutative semiring R with identity is said to be identity-summand if there exists $1{\neq}a{\in}R$ such that r+a = 1. In this paper, we introduce and investigate the identity-summand graph of R, denoted by ${\Gamma}(R)$. It is the (undirected) graph whose vertices are the non-identity identity-summands of R with two distinct vertices joint by an edge when the sum of the vertices is 1. The basic properties and possible structures of the graph ${\Gamma}(R)$ are studied.

• Structural Engineering and Mechanics
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• v.56 no.4
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• pp.535-548
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• 2015

A series of experimental results on thin mild steel plates clamped at the boundary subjected to gas detonation shock loading are presented. Detonation occurred by mixing Acetylene (C2H2)-Oxygen (O2) in various volume ratio and different initial pressure. The applied impulse is varied to give deformation in the range from 6 mm to 35 mm. Analytical modeling using energy method was also performed. Dependent material properties, as well as strain rate sensitivity, are included in the theoretical modeling. Prediction values for midpoint deflections are compared with experimental data. The analytical predictions have good agreement with experimental values. Moreover, it has been shown that the obtained model has much less error compared with those previously proposed in the literature.

• Journal of the Korean Mathematical Society
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• v.51 no.3
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• pp.593-607
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• 2014

Let R be an I-semiring and S(R) be the set of all identity-summand elements of R. In this paper we introduce the total graph of R with respect to identity-summand elements, denoted by T(${\Gamma}(R)$), and investigate basic properties of S(R) which help us to gain interesting results about T(${\Gamma}(R)$) and its subgraphs.

• Journal of the Korean Mathematical Society
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• v.52 no.1
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• pp.159-176
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• 2015

Let R be a semiring, I a strong co-ideal of R and S(I) the set of all elements of R which are not prime to I. In this paper we investigate some interesting properties of S(I) and introduce the total identity-summand graph of a semiring R with respect to a co-ideal I. It is the graph with all elements of R as vertices and for distinct x, $y{\in}R$, the vertices x and y are adjacent if and only if $xy{\in}S(I)$.

• Kyungpook Mathematical Journal
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• v.54 no.2
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• pp.237-247
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• 2014

The purpose of this paper is to introduce the concept of strongly extending modules which are particular subclass of the class of extending modules, and study some basic properties of this new class of modules. A module M is called strongly extending if each submodule of M is essential in a fully invariant direct summand of M. In this paper we examine the behavior of the class of strongly extending modules with respect to the preservation of this property in direct summands and direct sums and give some properties of these modules, for instance, strongly summand intersection property and weakly co-Hopfian property. Also such modules are characterized over commutative Dedekind domains.

• Geomechanics and Engineering
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• v.9 no.2
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• pp.207-218
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• 2015

In this paper, forming of fully clamped circular plate by using low velocity impact system has been investigated. This system consists of liquid shock tube and gravity drop hammer. A series of test on mild steel and aluminum alloy plates has been done. The effect of varying both impact load and the plate material on the deflection are described. This paper also presents a simple model to prediction of mid-point deflection of circular plate by using input-output experimental data. In this way, singular value decomposition (SVD) method is used in conjunction with dimensionless number incorporated in such complex process. The results of obtained model have very good agreement with experimental data and it provides a way of studying and understanding the plastic deformation of impact loads.

• Kyungpook Mathematical Journal
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• v.60 no.4
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• pp.673-682
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• 2020

For the recently defined notion of strongly lifting modules, it has been shown that a direct sum is not, in general, strongly lifting. In this paper we investigate the question: When are the direct sums of strongly lifting modules, also strongly lifting? We introduce the notion of a relatively strongly projective module and use it to show if M = M1 ⊕ M2 is amply supplemented, then M is strongly lifting if and only if M1 and M2 are relatively strongly projective and strongly lifting. Also, we consider when an arbitrary direct sum of hollow (resp. local) modules is strongly lifting.

• Bulletin of the Korean Mathematical Society
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• v.59 no.3
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• pp.685-695
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• 2022

The minimum number of complete bipartite subgraphs needed to partition the edges of a graph G is denoted by b(G). A known lower bound on b(G) states that b(G) ≥ max{p(G), q(G)}, where p(G) and q(G) are the numbers of positive and negative eigenvalues of the adjacency matrix of G, respectively. When equality is attained, G is said to be eigensharp and when b(G) = max{p(G), q(G)} + 1, G is called an almost eigensharp graph. In this paper, we investigate the eigensharpness and almost eigensharpness of lexicographic products of some graphs.

• Asian Pacific Journal of Cancer Prevention
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• v.16 no.17
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• pp.7831-7836
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• 2015

Background: Colorectal cancer (CRC) is one of the most common malignancies of the gastrointestinal tract. The aim of this study was to assess the general knowledge of CRC in individuals living in Rasht, Iran, using a population-based cross-sectional telephone survey. Materials and Methods: A total of 1557 participants between 18 and 80 years of age were interviewed using random sampling from the telephone directory. Knowledge of risk factors, symptoms, diagnosis, and prevention of CRC was assessed using a validated questionnaire. Results: The mean knowledge level of the 1,557 respondents (average age 46 y) was $13.5{\pm}4.29$ (maximum possible score = 26), and 46.4% (722/1,557) of the subjects achieved grades lower than the mean score. The mean scores for knowledge of symptoms and risk factors were $3.97{\pm}1.83$ (range: 0-7) and $5.17{\pm}1.65$ (range: 0-9), respectively. Older age, higher education, and employment were significantly associated with better scores for recognition of risk factors and warning symptoms. The majority of subjects correctly identified weight loss (70.2%; 1,093/1,557) and rectal bleeding (63.3%; 986/1,557) as symptoms of CRC, and that smoking (85.9%; 1,337/1,557) and a low-fiber diet (73.4%; 1,143/1,557) were risk factors. Approximately half of the subjects noted increasing age, genetic background and fried food as other risk factors. A considerable number (54.8%; 853/1,557) identified colonoscopy as a screening method for detecting CRC in asymptomatic patients. However, a third of the subjects in the target group for screening (${\geq}50y$) were not interested in undergoing screening, primarily due to a lack of symptoms. Conclusions: Our results suggest that the knowledge of CRC is poor among the public, and therefore greater attempts should be made to increase awareness. Public education emphasizing the risk factors and symptoms of CRC, as well as the importance of regular screening regardless of the presence of symptoms, may help to reduce CRC morbidity and mortality.