• Tunnel and Underground Space
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• v.24 no.1
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• pp.81-88
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• 2014

In the course of performing the stability analysis of rock structures, there are times when the strength of the Hoek-Brown rock mass needs to be understood in terms of the internal friction angle and cohesion. In this case, the original Hoek-Brown criteion, giving the relationship between ${\sigma}_1$ and ${\sigma}_3$ at failure, have to be transformed to the corresponding Mohr envelope. A new approach to derive the Mohr envelope of the Hoek-Brown criterion is suggested in this study. The new method is based on the Londe's transformation making the stress components dimensionless. The correctness of the derivation leading to the new ${\tau}-{\sigma}$ relationship is confirmed by comparing the calculation results with the Bray's solution through a verification example.

• Communications of the Korean Mathematical Society
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• v.27 no.3
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• pp.441-448
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• 2012

Let R be a prime ring with center Z and characteristic different from two, U a nonzero Lie ideal of R such that $u^2{\in}U$ for all $u{\in}U$ and $d$ be a nonzero (${\sigma}$, ${\tau}$)-derivation of R. We prove the following results: (i) If $[d(u),u]_{{\sigma},{\tau}}$ = 0 or $[d(u),u]_{{\sigma},{\tau}}{\in}C_{{\sigma},{\tau}}$ for all $u{\in}U$, then $U{\subseteq}Z$. (ii) If $a{\in}R$ and $[d(u),a]_{{\sigma},{\tau}}$ = 0 for all $u{\in}U$, then $U{\subseteq}Z$ or $a{\in}Z$. (iii) If $d([u,v])={\pm}[u,v]_{{\sigma},{\tau}}$ for all $u{\in}U$, then $U{\subseteq}Z$.

• Communications of the Korean Mathematical Society
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• v.31 no.1
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• pp.101-113
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• 2016

In this article, we considered the stability of the following (${\alpha}$, ${\beta}$, ${\gamma}$)-derivation $${\alpha}D[x,y]={\beta}[D(x),y]+{\gamma}[x,D(y)]$$ and homomorphisms associated to the quadratic type functional equation $$f(kx+y)+f(kx+{\sigma}(y))=2kg(x)+2g(y),\;x,y{\in}A$$, where ${\sigma}$ is an involution of the Lie $C^*$-algebra A and k is a fixed positive integer. The Hyers-Ulam stability on unbounded domains is also studied. Applications of the results for the asymptotic behavior of the generalized quadratic functional equation are provided.

• Journal of the Korean Mathematical Society
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• v.47 no.3
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• pp.495-504
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• 2010

This paper continues a line investigation in [1]. Let A be a K-algebra and M an A/K-bimodule. In [5] Hamaguchi gave a necessary and sufficient condition for gDer(A, M) to be isomorphic to BDer(A, M). The main aim of this paper is to establish similar relationships for generalized ($\sigma$, $\tau$)-derivations.

• Kyungpook Mathematical Journal
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• v.60 no.2
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• pp.415-421
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• 2020

In the proof of Theorem 3 on p.253 in [4], both right and left distributivity are assumed simultaneously which makes the proof invalid. We give a corrected proof for this theorem by introducing an extension of Lemma 2.2 in [2].

• Kyungpook Mathematical Journal
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• v.50 no.3
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• pp.379-387
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• 2010

In this paper, we present some results concerning orthogonal generalized (${\sigma},{\tau}$)-derivations in semiprime near-rings. These results are a generalization of result of Bresar and Vukman, which are related to a theorem of Posner for the product of two derivations in prime rings.

• Journal of the Korean Data and Information Science Society
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• v.10 no.1
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• pp.11-18
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• 1999

To estimate the mean and the variance of a lognormal distribution, Finney (1941) derived the uniformly minimun variance unbiased estimators(UMVUE) in the form of infinite series. However, the conditions ${\sigma}^{2}\;>\;n\;and\;{\sigma}^{2}\;<\;\frac{n}{4}$ for computing $E(\hat{\theta}_{AM})\;and\;E(\hat{\eta}^{2}_{AM})$ are necessary. In this paper, we give an alternative derivation of the UMVUE's.

• Honam Mathematical Journal
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• v.46 no.1
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• pp.1-11
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• 2024

In this paper, we introduce the notion of 𝜎-Jordan amenability of Banach algebras and some hereditary are investigated. Similar to Johnson's classic result, we give the notions of 𝜎-Jordan approximate and 𝜎-Jordan virtual diagonals, and find some relations between the existence of them and 𝜎-Jordan amenability.

• Korean Management Science Review
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• v.25 no.1
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• pp.75-91
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• 2008

Information strategy planning (ISP) pursues alignment of business strategy and IT (Information Technology) strategy as well as derivation of feasible and valuable IT projects. However, conventional ISP methodology hardly obtains the objectives because of its intrinsic shortcomings. Diverse ways are proposed for the improvement of the conventional methodology including, for example, combination of EA (Enterprise Architecture) with ISP. Meanwhile, six-sigma methodology which is characterized by quantification, scientific and systematic approach, customer orientation, process orientation has been gaining considerable attention and extending its application scope continuously. In this paper, an innovative ISP methodology is proposed by decomposing activities, methods, and tasks from conventional ISP process and reorganizing them into DMADOV six-sigma framework. In addition, the usefulness and applicability of the newly proposed methodology are provided using an electronics company example. The methodology enhance the possibility of producing future oriented and beneficial IT projects by associating IT strategy and the projects in the form of quantified causal relationship. Besides, it can also increase the objectivity of IT vision and strategy.

• Communications of the Korean Mathematical Society
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• v.10 no.2
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• pp.293-300
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• 1995

Let $R = k[y_1,\cdots,y_n] \otimes E[x_1, \cdots, x_n]$ with characteristic $k = p > 2$ (odd prime), where $$\mid$y_i$\mid$ = 2, $\mid$x_i$\mid$ = 1$ and $y_i = \betax_i, \beta$ is the Bockstein homomorphism. Topologically, $R = H^*(B(Z/p)^n,k)$. For a symmetric group $\sum_n, R^{\sum_n} = k[\sigma_1,\cdots,\sigma_n] \otimes E[d\sigma_1, \cdots, d\sigma_n]$ where d is the derivation satisfying $d(y_i) = x_i$ and $d(x_iy_i) = x_iy_i + x_jy_i, 1 \leq i, j \leq n$. We give a direct proof of this theorem by using induction.