• Proceedings of the Korea Concrete Institute Conference
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• 1997.10a
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• pp.527-532
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• 1997

Design strength of structural members could be determined by applying a strength reduction factor to nominal strength. At the beginning point of the transition region for the strength reduction factor, P=0.1$\sigma$$_{ck}A_g$, only sectional area and concrete strength are adopted as the variables of P=0.1$\sigma$$_{ck}A_g$. Therefore, P=0.1$\sigma$$_{ck}A_g$ is the empirically adopted which does not consider steel ratio, steel yielding stress, and steel arrangement. So, this research was perpormed the computer program for the analysis of axial force-moment-curvature relationship of reinforced concrete columns by sectional behaviour nonlinear analysis using a concrete compressive stress-strain curve, in order to investigate the ductility of reinforced concrete columns. As a result, ductility indicies of axial force, P=0.1$\sigma$$_{ck}A_g$, represented the lack of consistency of the indicies value for the various sections.

• Bulletin of the Korean Mathematical Society
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• v.46 no.3
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• pp.521-534
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• 2009

In this paper we present new large-update primal-dual interior point algorithms for $P_*$ linear complementarity problems(LAPS) based on a class of kernel functions, ${\psi}(t)={\frac{t^{p+1}-1}{p+1}}+{\frac{1}{\sigma}}(e^{{\sigma}(1-t)}-1)$, p $\in$ [0, 1], ${\sigma}{\geq}1$. It is the first to use this class of kernel functions in the complexity analysis of interior point method(IPM) for $P_*$ LAPS. We showed that if a strictly feasible starting point is available, then new large-update primal-dual interior point algorithms for $P_*$ LAPS have $O((1+2+\kappa)n^{{\frac{1}{p+1}}}lognlog{\frac{n}{\varepsilon}})$ complexity bound. When p = 1, we have $O((1+2\kappa)\sqrt{n}lognlog\frac{n}{\varepsilon})$ complexity which is so far the best known complexity for large-update methods.

• Journal of Korean Society of Environmental Engineers
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• v.39 no.3
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• pp.118-123
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• 2017

This study investigated the feasibility of a statistical approach for the prediction of BaP and total PAHs as pyrogenic sources. As results of regression, excellent linear and multiple correlations ($r^2$ > 0.94) were observed between BaP (or ${\Sigma}PAH$) and Pyr concentrations. When a developed prediction equation was applied to other investigations as validation and application studies, outstanding prediction results were obtained. The predictive model showed very good correlation between the measured and calculated ${\Sigma}PAH$. From this equation, Pyr was an apparently important hydrocarbon for the prediction of PAH. This model might provide a potentially useful tool for the calculation of average BaP and ${\Sigma}PAH$ in a certain region without additional tests.

• Atmosphere
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• v.21 no.3
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• pp.301-309
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• 2011

In this study, we compared light-absorption properties of aerosols observed in East and South Asia from black carbon (BC) mass concentration, aerosol scattering (${\sigma}_s$) and absorption (${\sigma}_a$) coefficients measurements at four sites: Korea Climate Observatory-Gosan (KCO-G), Korea Climate Observatory-Anmyeon (KCO-A), Maldives Climate Observatory-Hanimaadhoo (MCO-H) and Nepal Climate Observatory-Pyramid (NCO-P). No significant seasonal variations of BC mass concentration, ${\sigma}_s$ and ${\sigma}_a$, despite of wet removal of aerosols by precipitation in summer, were observed in East Asia, whereas dramatic changes of light-absorbing aerosol properties were observed in South Asia between dry and wet monsoon periods. Although BC mass concentration in East Asia is generally higher than that observed in South Asia, BC mass concentration at MCO-H during winter dry monsoon is similar to that of East Asia. The observed solar absorption efficiency (${\alpha}$) at 550 nm, where ${\alpha}={\sigma}_a/({\sigma}_s+{\sigma}_a)$, at KCO-G and KCO-A is higher than that in MCO-H due to large portions of BC emission from fossil fuel combustion. Interestingly, ${\alpha}$ at NCO-P is 0.14, which is two times great than that in MCO-H and is about 40% higher than that in East Asia, though BC mass concentration at NCO-P is the lowest among four sites. Consistently, the highest elemental carbon to sulphate ratio is found at NCO-P.

• Journal of applied mathematics & informatics
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• v.20 no.1_2
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• pp.75-96
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• 2006

Let m, n be positive integers. We denote by R(m,n) (respectively P(m,n)) the class of all groups G such that, for every n subsets $X_1,X_2\ldots,X_n$, of size m of G there exits a non-identity permutation $\sigma$ such that $X_1X_2{\cdots}X_n{\cap}X_{\sigma(1)}X_{/sigma(2)}{\cdots}X_{/sigma(n)}\neq\phi$ (respectively $X_1X_2{\cdots}X_n=X_{/sigma(1)}X_{\sigma(2)}{\cdots}X_{\sigma(n)}$). Let G be a non-abelian group. In this paper we prove that (i) $G{\in}P$(2,3) if and only if G isomorphic to $S_3$, where $S_n$ is the symmetric group on n letters. (ii) $G{\in}R$(2, 2) if and only if ${\mid}G{\mid}\geq8$. (iii) If G is finite, then $G{\in}R$(3, 2) if and only if ${\mid}G{\mid}\geq14$ or G is isomorphic to one of the following: SmallGroup(16, i), $i\in$ {3, 4, 6, 11, 12, 13}, SmallGroup(32, 49), SmallGroup(32, 50), where SmallGroup(m, n) is the nth group of order m in the GAP [13] library.

• The Journal of Information Systems
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• v.20 no.3
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• pp.1-24
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• 2011

Recently, six sigma has been widely adopted in a variety of industries as a disciplined, data-driven problem solving approach or methodology supported by a handful of powerful statistical tools in order to reduce variation through continuous process improvement. Also, data mining has been widely used to discover unknown knowledge from a large volume of data using various modeling techniques such as neural network, decision tree, regression analysis, etc. This paper proposes a six sigma methodology based on data mining for effectively and efficiently processing massive data in driving six sigma projects. The proposed methodology is applied in the hot stove system which is a major energy-consuming process in a "P" steel company for improvement of heat efficiency through reduction of energy consumption. The results show optimal operation conditions and reduction of the hot stove energy cost by 15%.

• Communications of the Korean Mathematical Society
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• v.28 no.3
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• pp.425-432
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• 2013

Let S be a minimal surface of general type with $p_g(S)=q(S)=0$ having an involution ${\sigma}$ over the field of complex numbers. It is well known that if the bicanonical map ${\varphi}$ of S is composed with ${\sigma}$, then the minimal resolution W of the quotient $S/{\sigma}$ is rational or birational to an Enriques surface. In this paper we prove that the surface W of S with $K^2_S=5,6,7,8$ having an involution ${\sigma}$ with which the bicanonical map ${\varphi}$ of S is composed is rational. This result applies in part to surfaces S with $K^2_S=5$ for which ${\varphi}$ has degree 4 and is composed with an involution ${\sigma}$. Also we list the examples available in the literature for the given $K^2_S$ and the degree of ${\varphi}$.

• Kyungpook Mathematical Journal
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• v.46 no.2
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• pp.219-229
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• 2006

Using the integral average method, we establish some oscillation criteria for the nonlinear differential equation with damped term $$a(t)|{x}^{\prime}(t)|^{\sigma-1}{x}^{\prime}(t)^{\prime}+p(t)|{x}^{\prime}(t)|^{\sigma-1}{x}^{\prime}(t)+q(t)f(x(t))=0,\;{\sigma}>1$$, where the functions $a,\;p$ and $q$ are real-valued continuous functions defined on $[t_o,{\infty})$ with $a(t)>0,\;f(x){\in}C^1(\mathbb{R})$ and $\frac{f^{\prime}(u)}{|f^{({\sigma}-1)/{\sigma}}(u)|}{\geq}k>0$ for $u{\neq}0$.

• Bulletin of the Korean Chemical Society
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• v.3 no.1
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• pp.13-18
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• 1982

The new substituent constants $({\sigma}^{\ast})$ are calculated from the acidity constants $(pK^{\ast})$ of phenol derivatives in the excited state ($^1L_b$). These substituent constant are applied to the Hammett equations and found good correlation with $pK^{\ast}$ of 2,6-di-tert-butyl phenol, benzamide, nitroaniline, thiophenol, azobenzene, and benzoic acid derivatives. The correlation was much better than that of ground state substituent constants such as ${\sigma},\;{\sigma}^+$, and ${\sigma}^-$. From these results, the new substituent constants $({\sigma}^{\ast})$are proposed to be used for the linear free energy relationship in the $^1({\pi},{\pi}^{\ast})$ excited states of phenyl compounds.

• Journal of the Korean Chemical Society
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• v.15 no.3
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• pp.147-152
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• 1971

On the baisis of the calculations by the two centre Huckel method for sigma electron system, the electronic structure of the various aliphatic amines including ammonia, and the relationship between the observed $pK_b$ and the change in the sigma electronic energy, ${\Delta}E{\sigma}$ in the course of protonation are discussed. A parallelism is observed between the $pK_b$ and the calculated ${\Delta}E{\sigma}$ of the amines. Also, it is observed that the electron densities of hydrogen atom directly bonded to nitrogen of the amines, likewise have a linear relationship with the $pK_b$. Therefore, the basicity of the aliphatic amines may be estimated qualitatively by means of the two center Huckel method.