• Proceedings of the Korea Concrete Institute Conference
• /
• 2001.11a
• /
• pp.239-244
• /
• 2001

Opens the construction market recently, the construction industry of Korea has faced up to the barrier of globalism, and has been enforced to follow the various global standards in many aspects. Accordingly, it is expected that the test method related to the cement and concrete will be changed to conform to the international standards in Korea. Therefore, in this study, the strength tests are executed for the cement mortars, made by KS and ISO standards respectively, and then obtains such results. 1) The flow of the cement mortar according to ISO is about 8% higher ,than that of KS. 2) The flexural strength of the cement mortar according to ISO is about 10~20% higher than that of KS, and the compressive strength is about 30% higher. 3) The compressive strength relation between the cement mortars of KS and ISO may be expressed in the first-order recurrence formula as follows: Y = 1.33X - 8 In which X is the compressive strength(kgf/$\textrm{cm}^2$) of the mortar according to KS and Y is the compressive strength(kgf/$\textrm{cm}^2$) of the mortar according to ISO.

• The Korean Journal of Applied Statistics
• /
• v.22 no.5
• /
• pp.1103-1113
• /
• 2009

We know that the first digits sequence of fibonacci numbers obey Benford's law. For the sequence in which the first two numbers are the arbitrary integers and the recurrence relation $a_{n+2}=a_{n+1}+a_n$ is satisfied, we can find that the first digits sequence of this sequence obey Benford's law. Also, we can find the stucture of the first digits sequence of this sequence with the exploratory data analysis tools.

• Journal of applied mathematics & informatics
• /
• v.26 no.3_4
• /
• pp.689-706
• /
• 2008

In this paper, a fifth order numerical method is presented for solving singularly perturbed two point boundary value problems with a boundary layer at one end point. The two point boundary value problem is transformed into general first order ordinary differential equation system. A discrete approximation of a fifth order compact difference scheme is presented for the first order system. An asymptotically equivalent first order equation of the original singularly perturbed two point boundary value problem is obtained from the theory of singular perturbations. It is used in the fifth order compact difference scheme to get a two term recurrence relation and is solved. Several linear and non-linear singular perturbation problems have been solved and the numerical results are presented to support the theory. It is observed that the present method approximates the exact solution very well.

• Journal of applied mathematics & informatics
• /
• v.28 no.1_2
• /
• pp.411-423
• /
• 2010

In this paper, a numerical method for singular perturbation problems arising in chemical reactor theory for general singularly perturbed two point boundary value problems with boundary layer at one end(left or right) of the underlying interval is presented. The original second order differential equation is replaced by an approximate first order differential equation with a small deviating argument. By using the trapezoidal formula we obtain a three term recurrence relation, which is solved using Thomas Algorithm. To demonstrate the applicability of the method, we have solved four linear (two left and two right end boundary layer) and one nonlinear problems. From the results, it is observed that the present method approximates the exact or the asymptotic expansion solution very well.

• Communications of the Korean Mathematical Society
• /
• v.33 no.2
• /
• pp.445-458
• /
• 2018

In this article we study the inclusion properties of the Bessel-Struve kernel functions in the Janowski class. In particular, we find the conditions for which the Bessel-Struve kernel functions maps the unit disk to right half plane. Some open problems with this aspect are also given. The third order differential subordination involving the Bessel-Struve kernel is also considered. The results are derived by defining suitable classes of admissible functions. One of the recurrence relation of the Bessel-Struve kernel play an important role to derive the main results.

• Journal of Trauma and Injury
• /
• v.28 no.1
• /
• pp.43-46
• /
• 2015

Although spontaneous resolution of chronic subdural hematoma (C-SDH) in the elderly has rarely been reported, spontaneous resolution of bilateral C-SDH is very rare. Here, we report the case of a 73-year-old female patient with no significant head trauma history who had a bilateral C-SDH spontaneously resolve despite receiving only conservative treatment. However, because of a lack of detailed knowledge about the mechanisms of resolution, treatment is often limited to surgical interventions that are generally successful, but invasive and prone to recurrence. We review the literature and discuss the possible relation of C-SDH's spontaneous resolution with its clinical and radiological characteristics.

• Honam Mathematical Journal
• /
• v.36 no.3
• /
• pp.531-542
• /
• 2014

Recently, Srivastava et al. [18] introduced the incomplete Pochhammer symbol and studied some fundamental properties and characteristics of a family of potentially useful incomplete hypergeometric functions. Here we introduce the incomplete Lauricella function ${\gamma}_D^{(n)}$ and ${\Gamma}_D^{(n)}$ of n variables, and investigate certain properties of the incomplete Lauricella functions, for example, their various integral representations, differential formula and recurrence relation, in a rather systematic manner. Some interesting special cases of our main results are also considered.

• Journal of applied mathematics & informatics
• /
• v.26 no.5_6
• /
• pp.1273-1287
• /
• 2008

In this paper, the numerical integration method for general singularly perturbed two point boundary value problems with mixed boundary conditions of both left and right end boundary layer is presented. The original second order differential equation is replaced by an approximate first order differential equation with a small deviating argument. By using the trapezoidal formula we obtain a three term recurrence relation, which is solved using Thomas Algorithm. To demonstrate the applicability of the method, we have solved four linear (two left and two right end boundary layer) and one nonlinear problems. From the results, it is observed that the present method approximates the exact or the asymptotic expansion solution very well.

• Communications for Statistical Applications and Methods
• /
• v.27 no.3
• /
• pp.377-383
• /
• 2020

The likelihood-based inference in a nonlinear generalized mixed model often requires computing moments of truncated multivariate normal random variables. Many methods have been proposed for the computation using a recurrence relation or the moment generating function; however, these methods rely on high dimensional numerical integrations. The numerical method is known to be inefficient for high dimensional integral in accuracy. Besides the accuracy, the methods demand too much computing time to use them in practical analyses. In this note, a moment calculation method is proposed under an assumption of a certain covariance structure that occurred mostly in generalized mixed models. The method needs only low dimensional numerical integrations.

• Journal of the Korean Mathematical Society
• /
• v.57 no.4
• /
• pp.1019-1030
• /
• 2020

Efficient computation of r-th root in 𝔽_q has many applications in computational number theory and many other related areas. We present a new r-th root formula which generalizes Müller's result on square root, and which provides a possible improvement of the Cipolla-Lehmer type algorithms for general case. More precisely, for given r-th power c ∈ 𝔽_q, we show that there exists α ∈ 𝔽_q^r such that $$Tr{\left(\begin{array}{cccc}{{\alpha}^{{\frac{({\sum}_{i=0}^{r-1}\;q^i)-r}{r^2}}}\atop{\text{ }}}\end{array}\right)}^r=c,$$ where $Tr({\alpha})={\alpha}+{\alpha}^q+{\alpha}^{q^2}+{\cdots}+{\alpha}^{q^{r-1}}$ and α is a root of certain irreducible polynomial of degree r over 𝔽_q.