• Bulletin of the Korean Mathematical Society
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• v.22 no.2
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• pp.95-98
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• 1985

In [1], E.B. Lee and L. Markus described a sufficient condition for which the domain of null-controllability of a linear autonomous system is all of R$^{n}$ . The purpose of this note is to extend the result to a certain linear nonautonomous system. Thus we consider a linear control system dx/dt = A(t)x+B(t)u in the Eculidean n-space R$^{n}$ where A(t) and B(t) are n*n and n*m matrices, respectively, which are continuous on 0.leq.t<.inf. and A(t) is a periodic matrix of period .omega.. Admissible controls are bounded measurable functions defined on some finite subintervals of [0, .inf.) having values in a certain convex set .ohm. in R$^{m}$ with the origin in its interior. And we present a sufficient condition for which the domain of null-controllability is all of R$^{n}$ .

• International Journal of Fuzzy Logic and Intelligent Systems
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• v.10 no.4
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• pp.296-302
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• 2010

This paper considers fuzzifying topologies, a special case of I-fuzzy topologies (bifuzzy topologies) introduced by Ying [16, (I)]. It investigates topological notions defined by means of regular open sets when these are planted into the frame-work of Ying's fuzzifying topological spaces (in ${\L}$ukasiewwicz fuzzy logic). The concept of fuzzifying nearly compact spaces is introduced and some of its properties are obtained. We use the finite intersection property to give a characterization of fuzzifying nearly compact spaces. Furthermore, we study the image of fuzzifying nearly compact spaces under fuzzifying completely continuous functions, fuzzifying almost continuity and fuzzifying R-map.

• Structural Engineering and Mechanics
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• v.37 no.5
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• pp.529-542
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• 2011

Three dimensional solutions for free vibrations analysis of functionally graded fiber reinforced cylindrical panel are presented, using differential quadrature method (DQM). The orthotropic panel is simply supported at the edges and is assumed to have an arbitrary variation of reinforcement volume fraction in the radial direction. Suitable displacement functions that identically satisfy the simply supported boundary condition are used to reduce the equilibrium equations to a set of coupled ordinary differential equations with variable coefficients, which can be solved by differential quadrature method to obtain natural frequencies. The main contribution of this work is presenting useful results for continuous grading of fiber reinforcement in the thickness direction of a cylindrical panel and comparison with similar discrete laminate composite ones. Results indicate that significant improvement is found in natural frequency of a functionally graded fiber reinforced composite panel due to the reduction in spatial mismatch of material properties.

• The Bulletin of The Korean Astronomical Society
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• v.41 no.1
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• pp.66.3-66.3
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• 2016

We report preliminary results from our analyses on the star-forming galaxies in the Herschel/SPIRE survey data over the AKARI/NEP-Wide Field. In this work, we utilize a combination of the SPIRE point source catalogue containing ~ 4,800 sources distributed over the wide (5.6 sq. deg) field and the spectroscopic redshift (zSPEC) data for 1790 selected targets obtained by MMT/Hectospec and WIYN/Hydra. Our analyses take advantages of multi-wavelengths photometric data (28 bands at most) covering from u* to $500{\mu}m$ band as well as continuous MIR wavelengths sampling by AKARI and WISE (4 to $25{\mu}m$). Various physical properties such as total infrared luminosity (LTIR), star formation rate (SFR), and luminosity functions (LFs) will be presented.

• The Pure and Applied Mathematics
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• v.17 no.4
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• pp.389-396
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• 2010

We investigate the existence of homoclinic orbits of the following systems of $Li{\'{e}}nard$ type: $a(x)x^'=h(y)-F(x)$, $y^'$=-a(x)g(x), where $h(y)=m{\mid}y{\mid}^{p-2}y$ with m > 0 and p > 1 and a, F, 9 are continuous functions such that a(x) > 0 for all $x{\in}{\mathbb{R}}$ and F(0)=g(0)=0 and xg(x) > 0 for $x{\neq}0$. By a series of time and coordinates transformations of the above system, we obtain sufficient conditions for the positive orbits of the above system starting at the points on the curve h(y) = F(x) with x > 0 to approach the origin through only the first quadrant. The method of this paper is new and the results of this paper cover some early results on this topic.

• Journal of the Korean Chemical Society
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• v.57 no.6
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• pp.761-768
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• 2013

Removal of COD and TSS from rice mill wastewater was investigated using continuous electrocoagulation method (CEC). The electrical energy consumption (EEC) of the process was also examined in order to evaluate the economic viability. The Box-Behnken statistical experiment design (BBD) and response surface methodology (RSM) were used to investigate the effects of major operating variables. Initial pH, current density, electrode distance and flow rate were selected as independent variables in BBD while COD removal, TSS removal and EEC were considered as the response functions. The predicted values of responses obtained using the response function was in good agreement with the experimental data. Optimum operating conditions were found to be pH of 7, current density of 15 mA $cm^{-2}$, electrode distance of 5 cm and flow rate of 70 ml/min. Under these conditions, greater than 89% removal of COD and TSS were obtained with EEC value of 7 KWh.

• Computers and Concrete
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• v.33 no.5
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• pp.573-594
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• 2024

This article presents a research study, with both laboratory and field tests, of a deep foundation in a markedly anisotropic medium. Particularly it has focused on the evaluation of the behavior of a pile, one meter in diameter, embedded in a rocky environment with difficult conditions, in the Flysch of the Spanish city of San Sebastián. To carry out the research, the site of a bridge over the Urumea River was chosen, which was supported by pre-excavated reinforced concrete piles. 4 borings were carried out, by the rotation and washing method, with continuous sampling and combined with flexible dilatometer tests. In the field, an Osterberg load test (O-cell) was performed, while in the laboratory, determinations of natural moisture, natural unit weight, uniaxial compressive strength (UCS), point load strength (PLS), compressive wave propagation velocity (V_c) and also triaxial and direct shear tests were carried out. The research results indicate the following: a) the empirical functions that correlate the UCS with the PLS are not always linear; b) for the studied Flysch it is possible to obtain empirical functions that correlate the UCS with the PLS and with the V_c; c) the bearing capacity of the studied Flysch is much greater than if it is evaluated by different load capacity theories; d) it is possible to propose an empirical function that allows evaluating the mobilized shear strength (τ_m), as a function of the UCS and the displacement relative of the pile (δ_r).

• Publications of The Korean Astronomical Society
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• v.32 no.1
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• pp.263-265
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• 2017

We present the mid-infrared (MIR) luminosity function (LF) of local (z < 0.3) star-forming (SF) galaxies in the North Ecliptic Pole (NEP) field. This work is based on the NEP-Wide point source catalogue and the spectroscopic redshift (z) data for ~ 1700 galaxies obtained by the optical follow-up survey with MMT/Hectospec and WIYN/Hydra. The AKARI's continuous $2-24{\mu}m$ coverage and the spectroscopic redshifts enable us to determine the spectral energy distribution (SED) in the mid-infrared and derive the luminosity functions of galaxies. Our $8{\mu}m$ LF finds good agreements with the results from SWIRE field over the wide luminosity range, while showing significant difference from the NOAO deep data in the faint end. The comparison with higher-z sample shows significant luminosity evolution from z > 0.3 to local universe. $12{\mu}m$ LF also shows a clear indication of luminosity evolution.

• Journal of applied mathematics & informatics
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• v.35 no.1_2
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• pp.121-130
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• 2017

This study is concerned with the existence of positive solution for the following nonlinear elliptic system $$\{-M_1(\int_{\Omega}{\mid}x{\mid}^{-ap}{\mid}{\nabla}u{\mid}^pdx)div({\mid}x{\mid}^{-ap}{\mid}{\nabla}u{\mid}^{p-2}{\nabla}u)\\{\hfill{120}}={\mid}x{\mid}^{-(a+1)p+c_1}\({\alpha}_1A_1(x)f(v)+{\beta}_1B_1(x)h(u)\),\;x{\in}{\Omega},\\-M_2(\int_{\Omega}{\mid}x{\mid}^{-bq}{\mid}{\nabla}v{\mid}^qdx)div({\mid}x{\mid}^{-bq}{\mid}{\nabla}v{\mid}^{q-2}{\nabla}v)\\{\hfill{120}}={\mid}x{\mid}^{-(b+1)q+c_2}\({\alpha}_2A_2(x)g(u)+{\beta}_2B_2(x)k(v)\),\;x{\in}{\Omega},\\{u=v=0,\;x{\in}{\partial}{\Omega},$$ where ${\Omega}$ is a bounded smooth domain of ${\mathbb{R}}^N$ with $0{\in}{\Omega}$, 1 < p, q < N, $0{\leq}a$ < $\frac{N-p}{p}$, $0{\leq}b$ < $\frac{N-q}{q}$ and ${\alpha}_i,{\beta}_i,c_i$ are positive parameters. Here $M_i,A_i,B_i,f,g,h,k$ are continuous functions and we discuss the existence of positive solution when they satisfy certain additional conditions. Our approach is based on the sub and super solutions method.

• Journal of the Chungcheong Mathematical Society
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• v.8 no.1
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• pp.111-117
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• 1995

A function $f:{\Omega}{\rightarrow}X$ is called intrinsically-separable valued if there exists $E{\in}{\Sigma}$ with ${\mu}(E)=0$ such that $f({\Omega}-E)$ is a separable in X. For a given Dunford integrable function $f:{\Omega}{\rightarrow}X$ and a weakly compact operator T, we show that if f is intrinsically-separable valued, then f is Pettis integrable, and if there exists a sequence ($f_n$) of Dunford integrable and intrinsically-separable valued functions from ${\Omega}$ into X such that for each $x^*{\in}X^*$, $x^*f_n{\rightarrow}x^*f$ a.e., then f is Pettis integrable. We show that a function f is Pettis integrable if and only if for each $E{\in}{\Sigma}$, F(E) is $weak^*$-continuous on $B_{X*}$ if and only if for each $E{\in}{\Sigma}$, $M=\{x^*{\in}X^*:F(E)(x^*)=O\}$ is $weak^*$-closed.