• 대한수학회보
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• 제59권2호
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• pp.453-468
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• 2022

In this article, we define a module M to be G^z-extending if and only if for each z-closed submodule X of M there exists a direct summand D of M such that X ∩ D is essential in both X and D. We investigate structural properties of G^z-extending modules and locate the implications between the other extending properties. We deal with decomposition theory as well as ring and module extensions for G^z-extending modules. We obtain that if a ring is right G^z-extending, then so is its essential overring. Also it is shown that the G^z-extending property is inherited by its rational hull. Furthermore it is provided some applications including matrix rings over a right G^z-extending ring.

• 대한수학회보
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• 제60권4호
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• pp.895-903
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• 2023

In this paper, we give some results on 2-strongly Gorenstein projective modules and related rings. We first investigate the relationship between strongly Gorenstein projective modules and periodic modules and then give the structure of modules over strongly Gorenstein semisimple rings. Furthermore, we prove that a ring R is 2-strongly Gorenstein hereditary if and only if every ideal of R is Gorenstein projective and the class of 2-strongly Gorenstein projective modules is closed under extensions. Finally, we study the relationship between 2-Gorenstein projective hereditary and 2-Gorenstein projective semisimple rings, and we also give an example to show the quotient ring of a 2-Gorenstein projective hereditary ring is not necessarily 2-Gorenstein projective semisimple.

• 마케팅과학연구
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• 제16권3호
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• pp.17-37
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• 2006

The present study examines the relative roles of external recommendations and internally felt satisfaction in influencing patient loyalty to a doctor. It establishes that recommendations do result in preliminary loyalty formation in the patient to the doctor, but only until the formation of own experiences; the significance of external sources of recommendation in the determination of patient loyalty becomes insignificant thenceforth. Implications for the doctors are that they should strive at fostering bonds of emotional attachment in their present patients so that they become strongly loyal and spread positive word-of-mouth which could result in the doctor getting new patients as well. Probable extensions of this research are also discussed later in the paper.

• 한국수학교육학회지시리즈B:순수및응용수학
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• 제31권3호
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• pp.251-265
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• 2024

The main aim of this article is to present new fixed point results concerning existence of selection for a multivalued map on hyperconvex product space taking values on bounded, externally hyperconvex subsets under some appropriate hypothesis. Our results are significant extensions of some pioneering results in the literature, in particular M. A. Khamsi, W. A. Krik and Carlos Martinez Yanez, have proved the existence of single valued selection of a lipschitzian multi-valued map on hyperconvex space. Some suitable examples are also given to support and understand the applicability of our results.

• Applied Microscopy
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• 제43권1호
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• pp.27-33
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• 2013

Inflammatory cells express the inflammatory cytokines and growth factors induced by lipopolysaccharide (LPS). Odontoblasts are located at the pulp-dentin interface and extend their cell processes far into the dentin where they are the first cells to encounter microorganisms or their products. Therefore, this study examined the expression of some growth factors related to the signal pathway, such as growth factor receptor binding protein 2 (Grb2)-Ras in odontoblast-like dental pulp cells, after a treatment with LPS. After 60 minutes, the mRNA and protein expression levels of Grb2 and Ras were higher in the LPS-treated cells than in the control cells. The level of vascular endothelial growth factor (VEGF) and basic fibroblast growth factor (bFGF) mRNA expression was increased significantly to a level similar to that of Grb2 and Ras at 60 minutes. The platelet-derived growth factor-AA (PDGF-AA) mRNA level was expressed strongly in the odontoblast like dental pulp cells without an association with LPS stimulation. Scanning electron microscopy revealed many extensions of the cytoplasmic processes and the number of processes increased gradually at 30, 60 and 90 minutes after LPS stimulation. From these results VEGF and bFGF expression might be induced through the Grb2-Ras signal transduction pathway in LPS treated odontoblasts.

• Journal of Mechanical Science and Technology
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• 제15권7호
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• pp.1002-1012
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• 2001

The work reported here is an extensive study of tendon response to multiple cyclic tests including 3% constant peak strain level test (A-type test), 3% constant peak strain level test with two rest periods (B-type test), and 3∼4% different peak strain level test (C-type test). A sufficient number of specimens were tested at each type of the test to statistically evaluate many changes in response during testing and differences in response between each type of the test. In cyclic tests, there were decreses (relaxations) in the peak stresses and hysteresis, increases in the slack strains, and during lower peak strain level (3%) cyclic block after higher peak strain level (4%) cyclic block in the C-type tests. Considering the results of this study and those of the other study of multiple cyclic tests with rest periods by Hubbard and Chun, 1985, recovery phenomena during the rest periods occurred predominantly at the beginning of the rest periods. Consistently in both studies, the effects of rest periods were small and transient compared to the effects of the cyclic extensions. The recovery with cycles at lower peak strain level (3%) after higher peak strain level (4%) in the C-type test has not been previously documented. This recovery seems to be a natural phenomena in tissue behavior so that collagenous structures recover during periods of decreased demand.

• Kyungpook Mathematical Journal
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• 제59권4호
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• pp.603-615
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• 2019

Let R be an associative unital ring with an endomorphism α and α-derivation δ. The constant products of elements in Ore extension rings, when the coefficient ring is reversible, is investigated. We show that if f(x) = ∑ⁿ_i=0 a_ixⁱ and g(x) = ∑^m_j=0 b_jx^j be nonzero elements in Ore extension ring R[x; α, δ] such that g(x)f(x) = c ∈ R, then there exist non-zero elements r, a ∈ R such that rf(x) = ac, when R is an (α, δ)-compatible ring which is reversible. Among applications, we give an exact characterization of the unit elements in R[x; α, δ], when the coeficient ring R is (α, δ)-compatible. Furthermore, it is shown that if R is a weakly 2-primal ring which is (α, δ)-compatible, then J(R[x; α, δ]) = N iℓ(R)[x; α, δ]. Some other applications and examples of rings with this property are given, with an emphasis on certain classes of NI rings. As a consequence we obtain generalizations of the many results in the literature. As the final part of the paper we construct examples of rings that explain the limitations of the results obtained and support our main results.

• 대한수학회보
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• 제45권2호
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• pp.285-297
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• 2008

For an endomorphism ${\alpha}$ of a ring R, the endomorphism ${\alpha}$ is called semicommutative if ab=0 implies $aR{\alpha}(b)$=0 for a ${\in}$ R. A ring R is called ${\alpha}$-semicommutative if there exists a semicommutative endomorphism ${\alpha}$ of R. In this paper, various results of semicommutative rings are extended to ${\alpha}$-semicommutative rings. In addition, we introduce the notion of an ${\alpha}$-skew power series Armendariz ring which is an extension of Armendariz property in a ring R by considering the polynomials in the skew power series ring $R[[x;\;{\alpha}]]$. We show that a number of interesting properties of a ring R transfer to its the skew power series ring $R[[x;\;{\alpha}]]$ and vice-versa such as the Baer property and the p.p.-property, when R is ${\alpha}$-skew power series Armendariz. Several known results relating to ${\alpha}$-rigid rings can be obtained as corollaries of our results.

• 한국CDE학회논문집
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• 제11권5호
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• pp.327-334
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• 2006

Recently, security incidents are growing rapidly in which internal employees let the drawing leak out to competitors or other countries. This type of security incidents has a characteristic that it occurs less frequently than other types of security incidents such as network or server security incident, but the damage is a lot more serious. The existing information security technologies to prevent internal information from being leaked out are only applicable to general documents(office documents, web pages and image files in which data are encrypted one by one). However, architectural drawings made up of collection of files with various formats(extensions) have problems with the process speed of en(de) cryption and accuracy, so the developments of security technologies by new methods are required. In this study, we design and develop a security technology based on work area with which users can protect the leakage of critical information in the kernel level while maintaining their work environment when they have to use sharing information that cannot be managed by the unit of file. As a result, we developed the "Virtual Secure Disk" which allows only authorized users and applications to have an access to drawings, and have verified its security by applying it to the actual company.

• 한국의류학회지
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• 제45권3호
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• pp.477-494
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• 2021

This study examined four subjects with close to average body-size values in four stages based on the average BMI value of middle-aged women aged 45 to 59 years. The first experimental pants was developed with two kinds of educational materials pants pattern. After using a clothing-suitability evaluation to identify problems, a pants pattern suitable for the body shape of middle-aged women was developed by modifying and supplementing the initial design. The fit assessment revealed that pattern A had a problem with wrinkles in the hip and thigh areas due to the long crotch length, and pattern B had a short bottom length, which caused the bottom to curl in toward the groin or for the bottom to stick at the hips. The second experimental pants was developed to address these issues and overall satisfaction with the dimensions was higher than for the first educational pattern. The proper front and rear length extensions satisfied movement functionality and appearance requirements, and increasing the gradient of the back centerline-rather than expanding the width of the back crotch-improved the functionality.